Finals Reviewer:

This is the reviewer for The Final Exam on Friday. A 100 item exam (scantron)  will be given.

Additional Requirements: FOR SUBMISSION ON FRIDAY:

Per group: Submit photomicrographs of at least 5 structures listed under each system.

1. Integumentary System:

• The skin is composed of two layers: the epidermis and the dermis. Underneath these layers lies the hypodermis. The epidermis is stratified squamous epithelium. The dermis is composed of a papillary layer and a reticular layer. The reticular layer of the dermis is made up of dense irregular connective tissue. The hypodermis is a layer of loose connective tissue.
• The epidermis is divided into five layers: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.
• The stratum basale contains the dividing cells. This layer is also called the stratum germinativum.
• The stratum spinosum consists of a layer several cells deep. The cells have pointy or spiny processes on them. The cells in the stratum granulosum contain keratohyaline granules.
• The stratum lucidum is present only in thick skin.
• The stratum corneum is the outermost layer. The cells in this layer are essentially bags of keratin. They contain no nuclei or organelles.
• Macrophages are mononuclear phagocytes. Many tissues have resident (fixed) macrophages. Fixed macrophages are given a unique name, depending on the tissue that they are located in. Kupffer cells are the hepatic macrophages. Histiocytes are macrophages seen in connective tissue. Dust cells are alveolar macrophage found in the respiratory tract. Langerhans cells are macrophages seen in the skin. Microglia are the central nervous system macrophages.
• Langerhans cells, keratinocytes, melanocytes, and Merkel cells are all found in the epidermis. The Langerhans cell is a phagocyte. The keratinocyte is the most abundant cell in the epidermis. The melanocyte produces melanin, which is responsible for skin pigmentation. The Merkel cell is a mechanoreceptor.
• The lunula is the half moon shaped white area on a nail. The anatomical term for the cuticle is the eponychium. The matrix is the region of the nails where there are dividing cells and nail growth. The nail plate rests on the nail bed. The nail root is the proximal portion of the nail that is underneath skin.
• The ceruminous glands of the ear are apocrine sweat glands.
• There are several different sensory receptors in the skin. The most abundant sensory receptor are the free nerve endings. Free nerve endings respond to pain and temperature. Ruffini's corpuscles respond to continuous pressure. Pacinian corpuscles respond to vibration and rapidly changing pressure. Krause's end bulbs are a receptor for fine touch which are located in mucous membranes and the tongue. Meissner's corpuscles are also a receptor for fine touch but they are located in the dermis.
• Hair is present over most of the body. It is not found on the palms of the hand, soles of the feet, urogenital openings, and lips.
• Mesenchyme is embryonic connective tissue. It is an undifferentiated tissue found in the embryo. Mucous connective tissue is a type of embryonic connective tissue; it is a subset of mesenchyme. Wharton's jelly is mucous connective tissue. Loose irregular connective tissue is areolar tissue. Dense irregular connective tissue is seen in the dermis. Dense regular connective tissue comprises tendons and ligaments.
• Psammoma bodies are collections of calcium. It is derived from the Greek word "psammos", which means sand.
• Corpora arenacea refers to the calcifications seen in the pineal gland. Corpora arenacea is nicknamed "brain sand".
• Hassall's corpuscles are the ring like structures found in the thymus.
• The spherical structures seen in some prostatic alveoli are called prostatic concretions.
• Pacinian corpuscles are pressure receptors in the skin.
• Ruffini endings, pacinian corpuscles, meissner's corpuscles, and merkel cells are all encapsulated sensory receptors. Free nerve endings are not encapsulated.

2.  Respiratory System

• The respiratory tract is made of branching structures, much like the branches of a tree. The trachea branches into two bronchi which branch into smaller bronchi. The bronchi ultimately branch into smaller bronchioles. Bronchioles are distinguished from bronchi in that they do not have cartilage and submucosal glands. The terminal bronchioles are the last part of the airway in which gas exchange does not occur. Terminal bronchioles lead to the respiratory bronchioles. The respiratory bronchioles are the first section of the respiratory tree that gas exchange can occur. The alveoli duct is analogous to a thoroughfare with many cul-du-sacs branching off of it. At the end of the alveoli duct is an alveoli sac. An alveoli sac is a cluster of alveoli, much like a cluster of grapes. Alveoli are individual sacs where gas exchange occurs.
• The conducting portion of the airway is where air is moved, warmed and moistened. The nasal cavities, pharynx, larynx, trachea and bronchi are all part of the conducting portion of the airway.
• The respiratory portion of the airway is where gas exchange occurs. The respiratory bronchioles, alveolar ducts, alveolar sacs and alveoli are all part of the respiratory portion.
• Respiratory mucosa is composed of ciliated pseudostratified columnar epithelium with goblet cells. Respiratory mucosa contains several cell types: ciliated cells, goblet cells, basal cells, and brush cells. Respiratory mucosa is located lining the respiratory segment of the nasal cavity. It lines the conchae and the paranasal sinuses.
• The trachea is lined by pseudostratified squamous epithelium. Epithelium lines body cavities and surfaces. Pseudostratified squamous epithelium is "pseudostratified" because it is only one cell layer thick, yet it appears to be stratified. In reality, every cell touches the basement membrane.
• The Clara cell is found in the terminal bronchioles. The type I pneumocyte is a squamous epithelial cell. It covers most of the surface of the alveoli. The type II pneumocyte is also called a septal cell. The type II pneumocyte secretes surfactant. The dust cell is also called the alveolar phagocyte. Brush cells are occasionally, but rarely, seen in the alveolar epithelium.
• Macrophages are mononuclear phagocytes. Many tissues have resident (fixed) macrophages. Fixed macrophages are given a unique name, depending on the tissue that they are located in. Kupffer cells are the hepatic macrophages. Histiocytes are macrophages seen in connective tissue. Dust cells are alveolar macrophages found in the respiratory tract. Langerhans cells are macrophages seen in the skin. Microglia are the central nervous system macrophages.
• Olfactory mucosa lines the roof and portions of the walls of the nasal cavity. It contains several cell types: basal cells, brush cells, olfactory cells and sustentacular cells.
• The epiglottis is part of the larynx. It is composed of elastic cartilage.
• The larynx is composed of several cartilages. The thyroid cartilage, cricoid cartilage, arytenoid cartilages, corniculate cartilages and cuneiform cartilages are all composed of hyaline cartilage. The epiglottis is elastic cartilage. There is no fibrocartilage in the larynx.
• Basal cells are located in the basal lamina. Brush cells are involved with general sensation of the olfactory mucosa. Olfactory cells are bipolar neurons that are the receptors for smell. Sustentacular cells are supporting cells. Sustentacular cells are most numerous cell type in the olfactory epithelium.
• The vestibule is lined by stratified squamous epithelium.

DIGESTIVE SYSTEM:

• The layers of the GI tract are: mucosa, submucosa, muscularis externa, and serosa or adventitia.
• The mucosa is the innermost layer of the GI tract. The mucosa consists of a lining epithelium, lamina propria and muscularis mucosae. Gut associated lymphatic tissue (GALT) is found in the mucosa and sometimes extends into the submucosa.
• The submucosa is comprised of dense irregular connective tissue. Within the submucosa are lymphatic vessels and nerve plexuses. Meissner's plexus is located in the submucosa.
• The muscularis externa consists of thick layers of smooth muscle. The myenteric plexus of Auerbach is located in the muscularis externa.
• The outer layer of the GI tract is either an adventitia or serosa. The serosa consists of only a single layer of epithelial cells (mesothelium) and underlying connective tissue. The adventitia is the outer layer of the GI tract when it is abutting another organ the posterior abdominal wall.
• The small intestine is the primary site for absorption of nutrients.
• There are several features of the small intestine.
• The lymphatic capillary within a villus of the small intestine is a lacteal.
• Crypts of Lieberkuhn are the intestinal glands.
• The plica circulares is a projection with a core of submucosa. The plica circulares is also called the valve of Kerckring.
• Microvilli that are seen on the epithelial cells in the small intestine form the brush border or striated border.
• Villi are finger like projections of mucosa seen in the small intestine.
• The mucosa is the innermost layer of the GI tract. It consists of epithelium, lamina propria, and muscularis mucosa.
• The submucosa is connective tissue. Within it are lymphatic vessels and nerve plexuses. Meissner's plexus is located in the submucosa.
• The muscularis externa consists of thick layers of smooth muscle. It contains Auerbach's plexus.
• The outer layer of the GI tract is either an adventitia or serosa. The serosa consists of only a single layer of epithelial cells and underlying connective tissue. The adventitia is the outer layer of the GI tract when it is abutting another organ the posterior abdominal wall.
• The masticatory mucosa is located on the hard palate and gingiva. Lining mucosa is found on the underside of the tongue, lips, cheek, and soft palate.
• The mucosa is the innermost layer of the GI tract. It consists of epithelium, lamina propria, and muscularis mucosa.
• The submucosa is connective tissue. Within it are lymphatic vessels and nerve plexuses. Meissner's plexus is located in the submucosa.
• The muscularis externa consists of thick layers of smooth muscle. It contains Auerbach's plexus.
• The outer layer of the GI tract is either an adventitia or serosa. The serosa consists of only a single layer of epithelial cells and underlying connective tissue. The adventitia is the outer layer of the GI tract when it is abutting another organ the posterior abdominal wall.
• The surface layer of masticatory mucosa is stratified squamous epithelium. (Remember, epithelium lines body cavities and covers body surfaces). The stratified squamous epithelium is keratinized. However, some regions of the masticatory mucosa are covered with non-keratinized stratified squamous epithelium and parakeratinized epithelium. Parakeratinized epithelium is similar to keratinized epithelium, except that in parakeratinized epithelium cell nuclei are present in the stratum corneum.
• The layers of the masticatory epithelium are similar to the layers of the epidermis. The stratum lucidum is not present in the masticatory epithelium.
• The epidermis is divided into five layers: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum. The stratum basale contains the dividing cells. This layer is also called the stratum germinativum. The stratum spinosum consists of a layer several cells deep. The cells have pointy or spiny processes on them. The cells in the stratum granulosum contain keratohyaline granules. The stratum lucidum is present only in thick skin. The stratum corneum is the outermost layer. The cells in this layer are essentially bags of keratin. They contain no nuclei or organelles.
• The papillae on the tongue are located anteriorly to the sulcus terminalis. The tongue contains primarily three types of papillae: filiform papillae, circumvallate papillae and fungiform papillae. The filiform papillae are the smallest and most abundant. Filiform papillae are the only papillae on the tongue which do not contain taste buds. Circumvallate papillae large papillae arranged in a "V" shape. Fungiform papillae are mushroom shaped. Foliate papillae are not well developed in man and are seen on the edges of the tongue. Taste buds are found on cicumvallate, fungiform, and foliate papillae.
• Chief cells secrete pepsinogen. Pepsinogen is the precursor for pepsin. Parietal cells are also called oxyntic cells. They secrete hydrochloric acid and intrinsic factor. Mucous neck cells contain mucinogen granules.
• The lining of the upper esophagus is stratified squamous epithelium. Epithelium lines body cavities and surfaces. Stratified squamous epithelium is "stratified" because it is more than one cell layer thick. "Squamous" refers to the fact that the surface cells of the layer are flat.
• The modifications of the muscularis externa seen on the large intestine are called teniae coli.
• The lymphatic capillary within a villus of the small intestine is a lacteal.
• Crypts of Lieberkuhn are the intestinal glands.
• The plicae circulares is a projection with a core of submucosa. The plicae circulares is also called the valve of Kerckring.
• Microvilli that are seen on the epithelial cells in the small intestine form the brush 
• border or striated border.
• Villi are finger like projections of mucosa seen in the small intestine.
• Brunner's glands are glands in the submucosa of the small intestine.
• Goblet cells are most numerous in the large intestine

3. Accessory Organs for Digestion:

• The pancreas is both an endocrine and exocrine organ.
• The endocrine portion of the pancreas is housed in the islets of Langerhans. Within the islets, there are several cell types. The alpha cells secrete glucagon. The beta cells secrete insulin. The delta cells secrete somatostain. The gamma cells secrete pancreatic polypeptide.
• The acini is the exocrine portion of the pancreas.
• Rokitansky-Aschoff sinuses are divertiuclae of the mucosa of the gallbladder. The small bile ducts which connec between the cystic duct and liver are the ducts of Luschka The duct of Wirsung is the pancreatic duct. The opening of the pancreatic duct into the duodenum is at the ampulla of Vater. The valves which regulates the flow of bile into the small intestine is the sphincter of Oddi.
• Hepatocytes are the liver cells. They are arranged to form a liver lobule, which is the functional unit of the liver. The liver lobule is a hexagonal shaped structure. At the angles of the liver lobule are portal triads. The portal triad is composed of a branch of the hepatic artery, portal vein, and bile duct. In the middle of the liver lobule is a central vein. Hepatic sinusoids run between the hepatocytes.
• The liver performs many, many functions. Estimates range at over 500 different functions for the liver.
• Bile production occurs in the liver. The liver receives blood from the hepatic artery and hepatic portal vein. The blood in the hepatic portal vein is the "first stop" directly from the intestines, giving the liver the prime opportunity to detoxify substances. The liver synthesizes proteins such as albumin, fibrinogen, and prothrombin. Fibrinogen (Factor I) and prothrombin (Factor II) are clotting factors involved in clotting. The liver also makes Factors VII, IX, and X.
• Cholecystokinin is produced by the mucosa of the gastrointestinal tract.
• The pancreas is both an endocrine and exocrine organ.
• The endocrine portion of the pancreas is housed in the islets of Langerhans. Within the islets, there are several cell types. The alpha cells secrete glucagon. The beta cells secrete insulin. The delta cells secrete somatostain. The gamma cells secrete pancreatic polypeptide.
• The acini is the exocrine portion of the pancreas.
• Glucose is converted to glycogen in the liver. Glycogen is stored in the liver. The liver stores of fat soluble vitamins (A, D, E, K). Cholesterol is synthesized in the liver.
• Once bile is produced by the liver, it is stored in the gallbladder.
• Urinary System:
• The kidney can be divided into an outer cortex and an inner medulla. A kidney lobe consists of a medullary pyramid, its overlying cortex, and the associated renal column. The renal columns are the tissue in between the pyramids. The nephron is the functional unit of the kidney. A region where a portion of the medulla project into the renal cortex are referred to as medullary ray.
• There are approximately one million (1,000,000) nephrons in each kidney. The nephron is the functional unit of the kidney.
• The functional unit of the kidney is the nephron. The nephron can be divided into the glomerulus and uriniferous tubule. The capillary tuft of the nephron is referred to as the glomerulus. Bowman's capsule is a double layered cap surrounding the glomerulus. This is the first portion of the uriniferous tubule. The glomerulus and Bowman's capsule make up the renal corpuscle. Another term for the renal corpuscle is Malpighian corpuscle.
• The afferent arteriole branches off the interlobular artery. The afferent arteriole supplies blood to the glomerulus. The glomerulus is a capillary tuft. The glomerular capillaries converge to form the efferent arteriole. The peritubular capillaries is a second capillary network which arise after the efferent arteriole. They surround the proximal tubule, loop of Henle, and distal tubule. Vasa recta are the "straight vessels" which arise from some of the efferent arterioles.
• Bowman's capsule leads to the proximal convoluted tubule. The proximal convoluted tubule leads to the loop of Henle. This then leads to the distal convoluted tubule. The distal convoluted tubule then leads to the collecting duct.
• Large collecting tubules near the apex of the pyramid are the ducts of Bellini. The ducts of Bellini are also called a papillary ducts.
• The inner layer of Bowman's capsule is the visceral layer. It consists of cells called podocytes. The outer layer of Bowman's capsule is the parietal layer. Pedicels are the foot processes on the podocytes. The juxtaglomerular cells secrete renin. The macula densa are specialized cells in the distal convoluted tubule that are sensitive to sodium. The juxtaglomerular cells and macula densa make up the juxtaglomerular apparatus
• The lining of the bladder is transitional epithelium. Epithelium lines body cavities and surfaces. There are domed shaped cells on the apical surface.

4. MALE REPRODUCTIVE SYSTEM

• Brunner's glands are found in the duodenum.
• Cilia is the hair like surface modification seen on some epithelia. Cilia are made of microtubules.
• Hormones can have a variety of structures. Hormones which are proteins include insulin and prolactin. Peptide chains are short chains of amino acids. Examples of hormones which are peptide chains are antidiuretic hormone and oxytocin. Steroid hormones are cholesterol derivatives. Steroid hormones include testosterone and estradiol. Norepinephrine and epinephrine are catecholamines.
• Keratinization is seen in the epidermis. Cells in the stratum corneum are essentially just bags of keratin.
• Leydig cells produce testosterone. These are also called "interstitial cells" or "interstitial cells of Leydig". Sertoli cells are directly involved in spermatogenesis. They are also called "sustentacular cells" or "nurse cells".
• Microvilli are the finger like projections seen on the surface of some cells. The appearance of microvilli form what is also called the brush border or striated border.
• Pseudostratified epithelium lines the epididymis.
• Sertoli cells produce inhibin and androgen-binding protein. The interstitial cells of Leydig produce testosterone.
• Skene's glands are also called the lesser vestibular glands and are found in females.
• Stereocilia are very long microvilli. Stereocilia are seen in the epididymis and the hair cells of the ear.
• The acrosome is the "cap" at the anterior portion of a spermatozoon.
• The average testis in an adult man has between 400 and 600 seminiferous tubules.
• The bulbourethral glands are also called Cowper's glands. The bulbourethral glands are found in males and are homologous to the Bartholin's glands in females.
• The corpora cavernosa and corpus spongiosum are erectile tissue. There are two corpora cavernosa and one corpus spongiosum.
• The corpus spongiosum is also called the corpus cavernosum urethrae. The corpora cavernosa and corpus spongiosum are erectile tissue. The corpus cavernosum clitoridis is in the female. The urethra is a muscular tube that runs from the bladder. It transports both urine and semen.
• The earliest cells of spermatogenesis are spermatogonia; these are primitive cells. The primary spermatocyte is derived from spermatogonia. This then develops into secondary spermatocytes . The secondary spermatocyte is haploid. These develop into spermatids. The mature sperm cell is spermatozoa.
• The glandular epithelium of the prostate is most often simple columnar, however a variety of types can be found.
• The male genital duct system contains: rete testes, tubuli recti, ductuli efferentes, ductus epididymidis, and ductus deferens. The male accessory glands contain the bulbourethral glands, seminal vesicles, and prostate.
• The prostate gland is found in males.
• The prostate is the largest accessory structure of the male reproductive system.
• The testes develop in the abdominal cavity.  
• The tunica albuginea is the thick capsule around each testis.

5. FEMALE REPRODUCTIVE SYSTEM
• A primordial follicle is a primary oocyte in the outer region of the cortex. It is  arrested in the first meiotic prophase. It is surrounded by flattened follicular  epithelial cells.
• During the first week to 10 days, FSH is the main hormone which stimulates the growth of the follicles. Ovulation is triggered by a dramatic increase in LH. During a pregnancy, HCG is the hormone which maintains the corpus luteum.
• The follicle which is ovulated is the Graffian follicle. The connective tissue layer around the primary follicle is the theca folliculi. The follicular cells are granulosa cells. The acidophilic glycoprotein coat surrounding the oocyte is the zona pellucida. A cavity within the follicle is the antrum.
• The mature follicle is also called the Graffian follicle.
• The ovary is covered with germinal epithelium. Underneath the germinal epithelium is connective tissue called the tunica albuginea. The outer region of the ovary is called the cortex. The inner region of the ovary is called the medulla. The ovarian follicle contains the oocyte.
• The ovary is covered with germinal epithelium. Underneath the germinal epithelium is connective tissue called the tunica albuginea. The outer region of the ovary is called the cortex. The inner region of the ovary is called the medulla. The ovarian follicle contains the oocyte.
• The term for the production of gametes is called gametogenesis. Gametogenesis in the female is referred to as oogenesis. The ovary is the organ where gametogenesis (oogenesis) occurs. Ovulation is the release of an oocyte and occurs every 28-30 days. The developing gametes are called oocytes. The mature gamete is an ova.
• The ovary is covered with germinal epithelium. Underneath the germinal epithelium is connective tissue called the tunica albuginea. The outer region of the ovary is called the cortex. The inner region of the ovary is called the medulla. The ovarian follicle contains the oocyte.
• The presence of the antrum is a characteristic of a secondary follicle. A follicle at this stage is also called an "antral follicle".
• The primary follicle is marked by the surrounding of flattened (squamous) follicular cells becoming cuboidal and the oocyte becomes bigger.

6. Go to this site:

Body Form

Click Body Form

Submit all the screen caps of all the contents of "Body Form Only"

Those with deficiencies (quiz/assignments) must submit all the requirements above INDIVIDUALLY.

ONLINE QUIZ ON SKIN, RESPIRATORY, URINARY SYSTEMS

Must submit as a PAIRED activity before 12:30 PM today 3/15/17
to dctrbautista522@gmail.com

Submit with the questions.

A. Identify the following layers of the skin:

1. ____________________ - Outermost layer of skin ____________________
2. ____________________ - Where melanocytes are found 
3. ____________________ - Layer of epidermis usually only found on palms of hands and soles of feet  
4. ____________________ - Not a layer of skin, mostly made of adipose tissue 
5. ____________________ -  Layer of dermis where touch and pain receptors are found as well as capillaries to provide nutrients to stratum basale. 
6. ____________________ - Site of most cellular division 
7. ____________________ - Layer of dermis where deep pressure receptors are found 
8. ____________________ - The thickest layer of skin, usually 20-30 layers of cells thick 
9. ____________________ - Where we get our finger prints from 
10. ____________________ - Layer of dermis where blood vessels, oil and sweat glands are found

B. What are the two types of sudoriferous glands? How are they different?

C. Enumerate the major skin structures that are housed in the two layers of the dermis.

D. Match the following photomicrographs with the correct labels

• Intraepithelial Gland Nasal Mucosa
• Alveolar Capillaries
• Nasal Respiratory Epithelium Goblet Cells
• Bronchiole 
• Olfactory Epithelium, Bowman's Glands
• Bronchus Mucosa & Cartilage
• Bronchus
• Larynx, True & False Voal Cords 
• Trachea Mucosa & Cartilage

1. ______________________
2. ____________________________________
3. ______________________
4. ______________________
5. ______________________
6. ______________________
7. ______________________
8. ______________________

E.  Label the following parts:

F. Match the following photomicrographs with the correct labels

Glomerulus

Ureter

bladder- full  

bladder- empty

Bowmann's space

Ureter -Transitional epithelium

Ureter - Lamina propria

Ureter - muscularis

Ureter - adventitia

1. ________________________________

2. ____________________________

3. ____________________________

4. __________________________________

5.    Label the specific layers of the urinary tract organ above

FINALS COVERAGE

Respiratory System Lab

Learning Objectives

• Describe the changes in the type of epithelium throughout the respiratory system
• Explain how the structure of different segments of the respiratory airways reflect the functional roles that these airways play in air movement and gas exchange
• Distinguish the trachea, bronchi, terminal bronchioles, bronchioles, alveolar ducts, alveolar sacs, and alveoli based on key structural features
• Identify the different types of pneumocytes and their functions
• Recognize key pathological conditions associated with the respiratory tract

Pre-Lab Reading

Introduction

The respiratory system consists of two divisions with distinct structural elements that reflect their unique functions. These include:

• The conducting airways, which serve to conduct, clean, warm, and moisten the air. This portion is composed of the nose, pharynx, larynx, trachea, bronchi, and bronchioles.
• The respiratory airways, which facilitate gas exchange. These are located entirely within the lung and are represented by respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.

Conducting Airways

The epithelium lining the respiratory tract from the nasal fossa through the bronchi is called the respiratory mucosa and is characterized by a pseudostratified ciliated epithelium with abundant non-ciliated cells known as goblet cells. In the lamina propria there are mixed seromucous (protein- and mucous-secreting) glands, lymphatic tissue, and broad veins.
The conducting airways are divided into two main sections:

• Extrapulmonary air conduits are located outside of the lungs and begin with the nose, pharynx and larynx. The trachea is continuous with the larynx above and the two primary bronchi below. It is the supporting framework for 16-20 C-shaped hyaline cartilages. These cartilage "bracelets" are open on the posterior wall of the trachea adjacent to the esophagus. A bundle of smooth muscle fibers bridges the gap between the two ends of the cartilage.
• Intrapulmonary air conduits extend from the intralobar bronchi to the terminal bronchioles. When the bronchi enter the lung, the C-shaped cartilages that characterize the trachea and primary bronchi are replaced by irregular plates or cartilage that completely surround the cylindrical muscular airway tube. Cartilage disappears in the terminal bronchioles, which have narrowed to a diameter of 1 millimeter. The terminal bronchioles initially have a ciliated columnar epithelium that soon transitions to a low cuboidal epithelium. Mucous and seromucous glands and diffuse lymphatic tissue are associated with smaller bronchi but are not found distal to the region where there is a loss of cartilage plates.

Respiratory Airways

The respiratory airways extend from the respiratory bronchioles to the alveoli.

• The respiratory bronchioles have a diameter of 0.5 millimeters and feature a few alveoli scattered along their walls. The epithelium here remains low cuboidal. Each respiratory bronchiole branches into between 2 and 11 alveolar ducts that still contain smooth muscle fibers in their walls. Along these walls, the alveolar ducts give rise to single alveoli and to numerous alveolar sacs, which are associated with 2 to 4 alveoli. The space at the entrance from the alveolar duct to an alveolar sac is referred to as the atrium.
• Alveoli can be studied most easily in preparations of expanded lung, especially in those areas in which erythrocytes have been retained in the capillaries. Alveoli have a distinct cup shape separated by loop- or crescent-shaped walls known as interalveolar septa. The interalveolar septa contain myriad capillaries.

The interface between the capillary lumen and the alveolar epithelium is known as the air-blood barrier. The barrier consists of the endothelium of the capillary, the epithelium of the alveolus, and their shared basement membrane.
The surface epithelium of the alveoli contains two developmentally related but functionally distinct cells, known as pneumocytes. Type I pneumocytes are attenuated vesicle-studded cells that line the alveolar walls near the capillaries. Only their flattened nuclei can be recognized with certainty by light microscopy. Type II pneumocytes are cuboidal and occur singly or in small clusters between type I cells. They contain 0.2 to 1 micron wide multilamellar bodies that contain a high content of phospholipid that is the precursor to pulmonary surfactant, which interferes with the surface tension in the alveoli that would otherwise cause them to collapse. Club (Clara) cells are also thought to participate in the synthesis of surfactant. Type II cells serve as precursors to type I cells.
Where there are no capillaries, the alveolar septum contains fibroblasts, collagen, elastic fibers, smooth muscle cells, and macrophages known as dust cells. Also notable are alveolar pores, which equalize air pressure between the alveoli.

Circulatory System of the Lung

Branches of the pulmonary artery accompany the bronchi to the level of the respiratory bronchioles. From there they branch into an extensive network of capillaries suspended within the alveolar walls. Venules arising from these capillaries join in the intersegmental connective tissue and later empty into the pulmonary veins. Bronchi and connective tissue septa within the lung are vascularized by branches of the bronchial arteries, which are part of the systemic circulatory system. These two systems anastomose at the level of alveoli arising from the respiratory bronchioles.

Lab Guide questions (SUBMIT ANSWERS INDIVIDUALLY)

1. Briefly describe the structural and functional differences between the following:
• Respiratory Bronchiole and Terminal Bronchiole
• Alveolar Sac and Alveolus
• Type I and Type II Pneumocyte
2.  Trace the path of a molecule of oxygen from the nose to the bloodstream. Make sure to include all major airways, as well as each layer of tissue that must be traversed.
3. Describe the changes in the type of epithelia encountered as the molecule of oxygen in the question above moves from the nose to the alveolus.
4. How the the cartilage present along the Upper respirtory Tract and surfactants ensure that the airways will remain open under the normal conditions of inhalation and exhalation. How do these work?
IN GROUPS: Submit
IN SOFT COPIES AND HARD COPIES (6 PICTURES/LONG WHITE PAPER - preferably recycled paper)

• Conducting Airway

• Conducting Epithelium
• Trachea
• Bronchus
• Intrapulmonary Air Conduits
• Bronchiole
• Respiratory Bronchioles
• Pneumocytes
• Pneumocytes EM
• Air-Blood Barrier

Urinary System Lab

Learning Objectives

• Distinguish the key microscopic components of the renal cortex and medulla
• Identify the structural components of the nephron
• Describe the structure of the surface across which filtration occurs
• Identify and distinguish the proximal tubule, distal tubule, and collecting duct
• Identify the component cells of the juxtaglomerular apparatus
• Name the important histological characteristics of the ureter, bladder, and urethra
• Describe some key pathological conditions associated with the kidney

Introduction

The urinary system is comprised of the kidney, ureter, urinary bladder, and urethra. The kidney produces urine, which contains excess water, electrolytes and waste products of the body. It then flows down the ureter into the bladder where it is temporarily stored. The bladder is then emptied via the urethra.

Kidney

The kidney has several important homeostatic, hormonal, and metabolic functions that include:

• The maintenance of water and electrolyte homeostasis
• Regulation of acid-base balance in conjunction with the respiratory system
• Excretion of metabolic waste products, especially the toxic nitrogenous compounds
• Production of renin for blood pressure control and erythropoietin, which stimulates red blood cell production in the bone marrow
• Conversion of vitamin D into active form for the regulation of calcium balance

The kidney is composed of an outer cortex and inner medulla. Portions of the medulla extend into the cortex as the medullary rays, collections of straight renal tubules. The medulla contains multiple cone-shaped lobes, known as medullary pyramids. These urinary lobes are fused in the cortex. The urine drains into the renal pelvis, which is the initial part of the ureter. The hilum of the kidney is the site of entry and exit for renal artery, renal vein, and ureter.

Nephron

The nephron is the structural and functional unit of the kidney. There are about two million nephrons in each kidney. Nephrons begin in the cortex; the tubules dip down to the medulla, then return to the cortex before draining into the collecting duct. The collecting ducts then descend towards the renal pelvis and empty urine into the ureter.
The components of a single nephron include:

• renal corpuscle
• proximal convoluted tubule
• loop of Henle
• distal convoluted tubule

Different sections of nephrons are located in different parts of the kidney:

• The cortex contains the renal corpuscle, proximal, and distal convoluted tubules.
• The medulla and medullary rays contain the loops of Henle and collecting ducts.

Throughout the length of the nephron, capillaries called peritubular capillaries lie adjacent to all segments of the tubule. They originate from the efferent arteriole and are important for solute transport throughout the tubule.

Renal Corpuscle

The renal corpuscle is responsible for the filtration of the plasma. It contains two structures: the glormerulus and Bowman's capsule. The glomerulus is a cluster of capillary loops enclosed by Bowman's capsule, which is part of the renal tubule.
Bowman's capsule has two layers:

• The visceral layer is in contact with the glormerulus, and is composed of specialized epithelial cells known as podocytes.
• The parietal layer is the outer layer, and is composed of simple squamous epithelial cells. This layer is continuous with the epithelium of the proximal convoluted tubule.

The space between the two layers is named Bowman's space, and this space contains the ultrafiltrate of plasma. The plasma has to pass through a filtration barrier of three layers to enter Bowman's space: the capillary endothelium, the podocyte layer, and their fused basement membrane. Bowman's space is continuous with the proximal convoluted tubule.
Blood enters the renal corpuscle via afferent arterioles and then leaves via efferent arterioles. The part of renal corpuscle where afferent and efferent arterioles are located is known as the vascular pole. On the opposite end of the vascular pole is where the renal tubule begins and is known as the urinary pole.
Mesangial cells can also be found within the glomerulus. These cells secrete a matrix of basement membrane-like material to support the structure of the glomerulus.

Promixal Convoluted Tubule

The proximal convoluted tubule is the first segment of renal tubule. It begins at the urinary pole of the glomerulus. This is where the majority (65%) of the glomerular filtrate is reabsorbed. The convoluted portion of the tubule leads into a straight segment that descends into the medulla within a medullary ray and becomes the loop of Henle.

Loop of Henle

The loop of Henle forms a hair-pin structure that dips down into the medulla. It contains four segments: the pars recta (the straight descending limb of proximal tubule), the thin descending limb, the thin ascending limb, and the thick ascending limb. The turn of the loop of Henle usually occurs in the thin segment within the medulla, and the tubule then ascends toward the cortex parallel to the descending limb. The end of the loop of Henle becomes the distal convoluted tubule near its original glomerulus. The loops of Henle run in parallel to capillary loops known as the vasa recta. Recall from Physiology that the loop of Henle serves to create high osmotic pressure in the renal medulla via the counter-current multiplier system. Such high osmotic pressure is important for the reabsorption of water in the later segments of the renal tubule.

Distal Convoluted Tubule

The distal convoluted tubule is shorter and less convoluted than the proximal convoluted tubule. Further reabsorption and secretion of ions occur in this segment. The initial segment of the distal convoluted tubule lies right next to the glomerulus and forms the juxtaglomerular apparatus.

Juxtaglomerular Apparatus

The juxtaglomerular apparatus is a specialized structure formed by the distal convoluted tubule and the glomerular afferent arteriole. It is located near the vascular pole of the glomerulus. The main function of the apparatus is the secretion of renin, which regulates systemic blood pressure via the renin-angiotensin-alodosterone system. The juxtaglomerular apparatus is composed of:

• The macula densa, a collection of specialized epithelial cells of the distal convoluted tubule. These cells are enlarged as compared to surrounding tubular cells. The cells of the macula densa sense sodium chloride concentration in the tubule, which in turn reflects the systemic blood pressure.
• The juxtaglomerular cells of the afferent arterioles, which are responsible for secreting renin. These cells are derived from smooth muscles cells of afferent arterioles.
• The extraglomerular mesangial cells, which are flat and elongated cells located near the macula densa. Their function is currently unclear.

Collecting Ducts

The terminal portion of the distal tubule empties through collecting tubules into a straight collecting duct in the medullary ray. The collecting duct system is under the control of antidiuretic hormone (ADH). When ADH is present, the collecting duct becomes permeable to water. The high osmotic pressure in the medulla (generated by the counter-current multiplier system/loop of Henle) then draws out water from the renal tubule, back to vasa recta.

Renal Pelvis and Ureter

Numerous collecting ducts merge into the renal pelvis, which then becomes the ureter. The ureter is a muscular tube, composed of an inner longitudinal layer and an outer circular layer. The lumen of the ureter is covered by transitional epithelium (also called urothelium). Recall from the Laboratory on Epithelia that the transitional epithelium is unique to the conducting passages of the urinary system. Its ability to stretch allows the dilation of the conducting passages when necessary. The ureter connects the kidney and the urinary bladder.

Urinary Bladder

The ureter empties the urine into the bladder. The transitional epithelium continues over the surface of this organ. The thickened muscular layers become interwoven and cannot be clearly identified at this point.

Urethra

The urethra carries the urine away from the bladder to the outside of the body. In the male, it is joined by the genital system. The epithelium changes from transitional to stratified or pseudostratified columnar in the urethra, and to stratified squamous in the distal end of the urethra.

Lab Guide questions (SUBMIT ANSWERS INDIVIDUALLY)

1. Match each section of the renal tubule with its function:

Proximal Tubule	A. filters the plasma
Distal Tubule	B. most reabsorption occurs here
Loop of Henle	C. generates countercurrent gradient
Collecting Duct	D. site of action of ADH
Renal Corpuscle	E. cells from the juxtaglomerular apparatus

2. Describe the function of each of the following cell types:

• Podocyte
• Mesangial Cell
• Macula Densa
• Juxtaglomerular Complex

3. Describe the changes in the epithelium as urine moves from the ureter through the urethra.

IN GROUPS: Submit
IN SOFT COPIES AND HARD COPIES (6 PICTURES/LONG WHITE PAPER - preferably recycled paper)

• Kidney
• Renal Corpuscle
• Renal Corpuscle 2
• Podocyte EM
• Podocyte Scanning EM
• Filtration Barrier
• Proximal Convoluted Tubule
• Proximal Convoluted Tubule EM
• Loop of Henle
• Distal Convoluted Tubule
• Juxtaglomerular Apparatus
• Collecting Ducts
• Renal Pelvis
• Ureter
• Urinary Bladder

Skin Lab

Learning Objectives

• Name and distinguish the four layers of the epidermis in terms of structure and function.
• Identify the two layers of the dermis and the hypodermis and explain their functional significance.
• Describe the basic structure and function of several key epidermal derivatives.
• Contrast the three modes of exocrine secretion and give examples of cells that exhibit each type.
• Describe the structure of the mammary glands.
• Recognize some key pathological examples affecting skin and epidermal derivatives.

Introduction

The skin is the largest organ of the body and varies greatly in different regions. It has five main functions: protection, thermoregulation, sensation, metabolic functions (vitamin D, adipose metabolism), and sexual attraction.
Skin is composed of several subunits. The three main divisions are:

• the epidermis, or surface epithelium, which is a self-regenerating stratified squamous epithelium that produces a protective protein layer of keratin.
• the dermis, an underlying layer of dense collagenous connective tissue that contains hair follicles, sweat glands, blood and lymphatic vessels, sensory receptors and nerves, and connective tissue cells.
• the hypodermis, another connective tissue layer that is rich in white adipose cells and contains large blood vessels that supply the smaller vessels of the dermis.

Epidermis

The epidermis is a stratified squamous epithelium that contains discrete layers of proliferating, differentiating, and differentiated cells called keratinocytes. It is divided into four layers that have different structural appearances:

• Basal Cell Layer - Keratinocytes begin in the deepest layer of the epidermis, the stratum basale, which is a row of columnar cells resting on the basal lamina that separates the epidermis from the dermis. Mitosis occurs exclusively at the basal cell layer and allows for the replacement of cells lost from the surface.
• Stratum Spinosum - After forming in the basal cell layer, keratinocytes migrate upwards into the stratum spinosum. In this layer, they develop short projections that attach via desmosomes to adjacent cells. The stratum spinosum is also known as the "prickly layer" because of these characteristic spines. The cells in this layer produce cytokeratin, an intermediate filament precursor to keratin.
• Stratum Granulosum - The third layer is the stratum granulosum. In this layer, the keratinocytes have become squamous cells that contain granules of keratohyaline, a precursor to the extracellular keratin that protects the skin tissue from abrasion.
• Stratum Corneum - The most superficial layer of the epidermis is the aceullar stratum corneum. It is the most functionally important layer of the skin and consists of flat, keratinized scales that are shed and replaced continuously. This is the layer that includes the final keratin product, which is a combination of cytokeratin and keratohyaline.

Recall from the Laboratory of Epithelia that epithelia differ in their degree of keratinization - those exposed to abrasion and desiccation are heavily keratinized, but those that form mucous membranes do not have much keratin. For example, the skin is highly keratinized, but the esophagus, anal canal,and vagina are not. Instead of protection by keratin, these mucous membranes are kept moist by glandular secretions. Mucous membranes lack a stratum granulosum and stratum corneum.

The epidermis contains several characteristic cell types:

• Melanocytes occur at intervals among the basal keratinocytes and produce melanin pigment, which is most abundant in sun-exposed skin and in areas surrounding body openings. Melanin is synthesized from tyrosine and transferred as melanin granules to the surrounding epithelial cells. While the number of melanocytes is the same in light- and dark-skinned people, they are far more active in the latter.
• Langerhans cells are typically located in the stratum spinosum and are the equivalent of macrophages in the skin tissue.
• Merkel cells are attached to keratinocytes by desmosomes and are most commonly found in highly sensitive areas like the fingertips - these serve as touch receptors.

Dermis and Hypodermis

The dermis consists of two layers:

• Papillary layer - The most superficial layer of the dermis is the papillary layer, which consists of loose connective tissue immediately beneath the epidermal basement membrane.
• Reticular layer - The reticular layer is composed of dense, irregular collagenous connective tissue.

Most blood vessels, nerves, and sensory receptors occur in the papillary layer. This region also contains Meissner's corpuscles, which sense light touch.
The hypodermis is the fatty layer beneath the dermis. It is thickest in the abdominal wall and virtually absent in the eyelid, scrotum, penis, and the dorsal side of the hand. This layer contains a significant number of fibroblasts, which synthesize collagen and elastin. The hypodermis contains Pacinian corpuscles, which sense deep touch.

Epidermal Derivatives

Many structures are derived from epidermal tissue. Keep in mind that just because a structure is derived from the epidermis does not mean that it is located in the epidermis.
Hair follicles are encased by an invagination of the epidermis into the dermis known as the external root sheath. They contain specially organized keratin built into long tubular structures. Remember that hair follicles have generous blood and nerve supplies. There are three states of hair follicles:

• Anagen - Growing follicles synthesize hair. They are long and most numerous in the scalp.
• Catagen - Resorbing follicles are in a short phase of regression that signals the end of active hair growth.
• Telogen - Resting follicles contain a fully formed hair.

- Sebaceous glands are pear-shaped alveolar glands that secrete an oily substance called sebum, which moisturizes and waterproofs hair. 

      - They are usually attached to hair follicles near the arrector pili muscle, which allows the hair to "stand up." 

      - An extensive capillary plexus characterizes sebaceous glands.
- Eccrine sweat glands occur throughout most of the skin. 

      - They consist of long tubules extending from the epidermis deep into the dermis or hypodermis. 

      - The secretory portion of each gland is tightly wound and appears as a collection of cross-sectioned tubules. 

      - It is encased by myoepithelial cells, which contain actin filaments. 

      - These cells receive input from nerve fibers, which cause them to contract and expulse the sweat from the gland. 

      - Do not have eccrine sweat glands: the glans penis, the inner surface of the foreskin, the clitoris, and the labia minora.
- Apocrine sweat glands are much larger than eccrine glands and produce a thicker secretion. 

     - They have straight, narrow ducts that run parallel to hair follicles and frequently open into the pilosebaceous canal. 

     - These sweat glands occur in the axilla, the areola of the nipple, the labia majora, and the circumanal region.

Mammary Glands

Mammary glands are one of the most complex epidermal derivatives. These glands are present in both sexes, but only develop fully in females after parturition. They begin to undergo dramatic structural changes at puberty.
The basic structure of the mammary glands involves alveoli that contain two layers of cells: an inner cuboidal epithelium and an outer layer of myoepithelial cells. The alveoli make up tubuloalveolar glands, or lobes, which connect via lactiferous ducts to the base of the nipple. After milk is produced, it is secreted and travels through the ducts into spindle-shaped enlargements beneath the areola known as lactiferous sinuses.
Important structural changes occur in the mammary glands over the course of the female's lifetime:

• In a nonpregnant, sexually mature female, the glandular tissue consists of ducts with small terminal alveoli embedded in an abundant connective tissue stroma that contains many adipose cells.
• During pregnancy, hormonal stimulation results in the proliferation of the intralobar ducts and terminal alveoli. The epithelial cells become enlarged and vacuolated, as milk fat production increases.
• After parturition, the gland enters its active secretory phase and produces watery milk containing membrane-bound lipid droplets, as well as milk proteins, lactose, and cellular debris.
• Suckling causes release of prolactin from the anterior pituitary and oxytocin from the posterior pituitary (processes that you will study in detail during Physiology). Prolactin maintains milk production and oxytocin causes the contraction of myoepithelial cells and ejection of milk.

Types of Exocrine Secretion

In your study of Histology, you may hear three different terms to describe exocrine cells. These can often be confusing.

• Merocrine, or eccrine, secretion occurs by exocytosis. This is the mode of secretion of both eccrine and apocrine glands, which can be very confusing.
• Apocrine secretion occurs when a portion of the plasma membrane containing the secretion buds off from the cell. This is the mode of secretion of the mammary glands and mucous-producing cells, but not the apocrine sweat glands.
• Holocrine secretion occurs when the entire cell disintegrates in order to release its secretion. Sebaceous glands exhibit holocrine secretion, as the sebum is released with remnants of dead cells.

Pre-Lab Guide questions (SUBMIT ANSWERS IN PAIRS) 

(Yellow pad to be submitted on 3-8-17)

1. Name the four layers of the epidermis and the state of keratin associated with each.
2. What are the important differences between sebaceous glands, eccrine sweat glands, and apocrine sweat glands?
3. What is the structure of the mammary gland, and what key differences do you expect to see between active and inactive mammary tissue?
4. Name the three types of exocrine secretion, their key characteristics, and an example of a cell that demonstrates each one.

ASSIGNMENT/TAKE HOME ACTIVITY:

IN GROUPS: SUBMIT PHOTOMICROGRAPHS OF THE FOLLOWING ON FRIDAY (3-10-17) - IN SOFT COPIES AND HARD COPIES (6 PICTURES/LONG WHITE PAPER - preferably recycled paper)

LABEL THE SPECIFIC PARTS OF EACH:

1. Skin
2. Epidermis
3. Stratum Basale and Stratum Spinosum
4. Stratum Basale and Stratum Spinosum EM
5. Stratum Granulosum and Stratum Corneum
6. Melanocytes and Langerhans Cells
7. Pacinian Corpuscle
8. Meissner's Corpuscle
9. Hair
10. Hair Follicle
11. Sebaceous Glands
12. Eccrine Sweat Glands
13. Apocrine Sweat Glands
14. Inactive Mature Breast
15. Active Mature Breast
16. Breast Acini

MUST STUDY all the pictures before attending the lab. A POST LAB QUIZ WILL BE GIVEN.