Pre-midterm exam Reviewer Pointers

Connective Tissue Generalities

• Of the four basic tissue types (epithelium, connective tissue, muscle and nervous tissue), connective tissue is the most diverse. 
• Blood, bone, tendon, and intervertebral discs are all composed of connective tissue. 
• The myometrium is the muscular layer of the uterus. 
• Thus, the myometrium is composed of muscle tissue.
• There are three types of fibers found in connective tissue: collagen fibers, elastic fibers, and reticular fibers. 
• Collagen fibers are the most abundant fiber type in connective tissue.
• Purkinje fibers are seen in the heart. 
• Purkinje fibers are specialized muscle fibers.
• Myofibroblasts contain properties of both fibroblasts and smooth muscle cells.
• Fibroblasts, histiocytes, plasma cells, and mast cells are routinely seen in loose connective tissue. 
• Fibroblasts produce collagen. 
• The fibroblast also produces the ground substance in connective tissue. 
• Myofibroblasts contain properties of both fibroblasts and smooth muscle cells. 
• The histiocyte is a connective tissue macrophage. 
• Plasma cells are derived from B lymphocytes. 
• Mast cells secrete histamine. 
• Mast cells also secrete heparin, SRS-A (slow reacting substance of anaphylaxis, ECF-A (eosinophilic chemotactic factor of anaphylaxis.
• 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.
• Connective tissue can be sub-classified into connective tissue proper, specialized connective tissue and embryonic connective tissue.
• Connective tissue proper consists of loose irregular connective tissue and dense connective tissue (regular and irregular).
• Specialized connective tissue includes cartilage, bone, adipose tissue, blood and hemopoietic tissue, and lymphatic tissue.
• Embryonic connective tissue includes mesenchyme and mucous connective tissue.
• Connective tissue can be sub-classified into connective tissue proper, specialized connective tissue and embryonic connective tissue.
• Connective tissue proper consists of loose irregular connective tissue and dense connective tissue (regular and irregular).
• Specialized connective tissue includes cartilage, bone, adipose tissue, blood and hemopoietic tissue, and lymphatic tissue.
• Embryonic connective tissue includes mesenchyme and mucous connective tissue.
• 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.
• Brown adipose tissue is multilocular adipose tissue. 
• This is present during fetal development and then decreases after birth.
• White adipose tissue is unilocular adipose tissue. 
• This type of tissue persists into adulthood.
• A peripheral blood smear would be best visualized with Wright's stain.
•  Hematoxylin and eosin stain is the most commonly used tissue stain for routine histological examination. 
• Lipids are best displayed with a sudan stain. 
• Silver impregnation, such as with a reticular stain, can be used to visualize reticular fibers. 
• Collagen fibers can be differentiated from other fibers by staining with Masson's trichrome stain.

Blood 

• There are four basic tissue types: epithelium, connective tissue, muscle and nervous tissue. 
• Connective tissue is the most diverse. 
• Blood is considered a type of connective tissue.
• Blood is composed of the formed elements and plasma. 
• Plasma is the liquid portion of blood. 
• The formed elements consist of the cells and cell fragments. 
• The erythrocytes (red blood cells), platelets, and leukocytes (white blood cells) are all considered formed elements.
• Erythrocytes do not contain a nucleus. 
• During their development within the bone marrow, they have a nucleus. 
• However, prior to their entering into the blood stream, the nucleus is ejected.
• Platelets are cell fragments. 
• Platelets also do not contain a nucleus. 
• They are fragments from megakaryocytes within the bone marrow. 
• Leukocytes, which include monocytes, are cells with a nucleus.
• Platelets are cell fragments. 
• They are fragments from megakaryocytes within the bone marrow.

• Neutrophils are the most abundant leukocyte.
• Leukocytes are the white blood cells.
• The order of frequency of the leukocytes is: neutrophil, lymphocyte, monocyte, eosinophil, basophil. The order of frequency of the leukocytes can be remembered by the mnemonic: "Never Let Monkeys Eat Bananas".
• The granulocytes are named because of the presence of visible cytoplasmic granules. 
• The granulocytes consist of neutrophils, eosinophils, and basophils. 
• "PMN" is an abbreviation for polymorphonuclear neutrophil. 
• Thus, it is a neutrophil, which is a granulocyte. 
• The non-granulocytes are lymphocytes and monocytes.

Muscle Tissue

• The fundamental property of muscle tissue is that it is specialized for contraction.
• The outer connective tissue covering of a muscle is the epimysium. 
• Within the muscle, there are subdivisions called fascicles. 
• The perimysium surrounds these muscle fascicles. 
• The perimysium is the connective tissue sheath which surrounds muscle fascicles.
• The periosteum is the connective tissue covering of a bone.
• The perichondrium is the connective tissue which surrounds cartilage.
• The perineurium is the covering of nerve fascicles.
• The endosteum is the lining of the inner bone (the side which abuts the medullary cavity).
• The endomysium is the covering around an individual muscle fiber. 

• The sarcolemma is the plasma membrane of a muscle cell. 
• The sarcoplasm is the cytoplasm of a muscle cell.
• Myofilaments are the contractile protein within a muscle cell. 
• On a cross section of a muscle, each thick filament is surrounded by 6 thin filaments.
• The myofilaments are actin and myosin. The thin filaments are actin and the thick filaments are myosin. 
• The muscle cell is a muscle fiber. The term "muscle cell" and "muscle fiber" are synonymous. 
• A myofibril is a longitudinal bundle of myofilaments within a muscle cell. 
• Myocardium is the muscular layer of the heart. 
• Thus, the myocardium is composed of cardiac muscle.
• There are two chief categories of muscle: striated and non striated muscle (smooth muscle).
• Striated muscle can be sub-categorized into cardiac muscle and skeletal muscle. The tongue, biceps muscle, and upper esophagus are made of striated muscle. The heart is composed of cardiac muscle.
• Non striated muscle is also called smooth muscle. Smooth muscle is involuntary muscle. It is found in viscera and blood vessels.
• Smooth muscle is composed of spindle shaped cells.
• Skeletal muscle is multinucleated. The nuclei are seen on the periphery. Occasionally, cardiac muscle is bi-nucleated.
• Skeletal muscle fibers can be classified as red fibers, white fibers or intermediate fibers. 
• Red fibers are smaller in diameter; white fibers are larger in diameter. 
• Red fibers have more mitochondria than white fibers. 
• Red fibers make up slow-twitch muscle; white fibers make up fast-twitch muscle. 
• Red fibers are more resistant to fatigue than are white fibers. 
• Red fibers have more myoglobin (oxygen binding pigment) than white fibers. 
• White fibers store glycogen and use anaerobic metabolism.
• Red fiber and slow twitch muscle is for endurance.
• White fiber and fast twitch muscle is for a burst of power.
• The A band is the darker staining band. 
• The I band is the light band. 
• The I band is made of thin filaments. 
• The Z line runs through the I band. 
• The H band bisects the A band. The M line runs through the H band.
• A sarcomere is the segment that runs from Z line to Z line.
• Both skeletal muscle and cardiac muscle have visible striations. Collectively, skeletal muscle and cardiac muscle are classified as "striated muscle".
• A single motor neuron and the aggregation of muscle fibers innervated by that single neuron is called the motor unit. 
• A motor neuron is a neuron which innervates a muscle cell. 
• The point of contact where a neuron contacts a muscle is the motor end plate. 
• A neuromuscular spindle is a receptor which is sensitive to stretching of the muscle. 
• A neurotransmitter is the chemical released by a nerve at a synapse.

BoneTissue

• Of the four basic tissue types (epithelium, connective tissue, muscle and nervous tissue), connective tissue is the most diverse. 
• Bone is a type of connective tissue.
• "Bone" can refer to either a type of tissue or to the organ. 
• As a tissue, bone tissue is a type of connective tissue. 
• When referring to a bone (the organ), there will be several types of tissue present.
• Compact bone is also called dense bone. 
• Compact bone has the Haversian system.
• Immature bone is woven bone. 
• It is nonlamellar bone or bundle bone.
• Spongy bone is also referred to as cancellous bone. 
• The mineralized tissue is seen as spicules. 
• Marrow spaces are also present.
• An osteoclast is a multinucleated cell involved in the degradation of bone. 
• It is a bone resorbing cell.
• An osteon is the cylindrical structure with bone. 
• An osteon is also called a Haversian system.
• The mature bone cell is called an osteocyte. 
• It sits in a space, called a lacuna.
• An osteoblast is an immature bone cell. 
• The osteoblast is the bone forming cell.
• Osteoid is unmineralized bone matrix.
• Canaliculi are the little tunnels within bone.
• Sharpey's fibers are collagen fibers that extend into a bone at an angle.
• Trabeculae are the spicules seen with spongy bone.
• Tome's process is seen in teeth, this process is responsible for enamel production.
• An osteocyte rests in a space called a lacuna.
• The mature cell in cartilage is a chondrocyte. 
• It rests in a lacunae surrounded by matrix. 
• A chondroblast is an immature cartilage cell which produces the cartilaginous matrix. 
• An osteocyte is a mature bone cell. 
• An osteoclast is a bone cell which is involved in resorption of bone. 
• A bone lining cell is a resting osteoblast.
• Intramembranous bone formation is the process of bone formation where the bone is formed without a cartilage template. 
• Endochondral bone formation is the process of bone formation where the bone is formed using a cartilage template.
• Hyaline cartilage forms the epiphyseal growth plate.
• The mature cell in cartilage is a chondrocyte. It rests in a lacunae surrounded by matrix. A chondroblast is an immature cartilage cell which produces the cartilaginous matrix. An osteocyte is a mature bone cell. An osteoclast is a bone cell which is involved in resorption of bone. A bone lining cell is a resting osteoblast.
• Calcium is in a mineral structure in bone and tooth enamel called hydroxyapatite. 
• The chemical formula is [Ca10 (PO4)6(OH)2]
• Calcite crystals are calcium carbonate. 
• The main component of limestone is calcite and seashells are made of calcite. 
• However, calcite crystals are not found in man.
• Tourmaline is a crystal found in nature. 
• Pink-red tourmaline is called rubellite. 
• Blue tourmaline is known as indicolite. 
• Tourmaline crystals are not found in man, although sometimes they are found on the necks and fingers of women in the form of jewelry.
• Red marrow contains active hematopoietic tissue. Yellow marrow is primarily fat.

Nervous Tissue:

• Schwann cells are responsible for the myelination of neurons in the peripheral nervous system. 
• Basket cells are a type of neuron seen in the cerebellum. 
• A ganglion is a collection of nerve cell bodies outside of the CNS. 
• Neuroglia are the supporting cells in the central nervous system 
• Sometimes, neuroglia called glial cells or glia. 
• Satellite cells are found in the ganglia of the peripheral nervous system.
• The central nervous system consists of the brain and spinal cord. 
• All other nervous system elements are considered to be in the peripheral nervous system. 
• Thus the peripheral nervous system includes receptors, the brachial plexus, the sciatic nerve, and ganglia.
• Most neurons in the body (over 99%) are multipolar.
• Neurons can be classified based on the number of axons and dendrites stemming off of the cell body. 
• A unipolar neuron has one process which branches off of it This process then immediately divides into two. Thus, a unipolar neuron is sometimes also called a pseudounipolar neuron. Sensory neurons are unipolar.
• A bipolar neuron has two process that branch from it: an axon and a dendrite. 
• Bipolar neurons are not very common and are found in some of the organs for special senses. 
• Bipolar neurons are found in the retina, inner ear, and the region of the nose involved with smell.
• Multipolar neurons have one axon and many (at least two) dendrites that branch off of it. 
• Most neurons are multipolar. 
• Motor neurons and interneurons are multipolar.
• A ganglion is a collection of neuron cell bodies outside of the central nervous system. 
• The cell body of a neuron is called a perikaryon or soma. 
• An astrocyte is a supporting cell seen in the central nervous system. 
• The basophilic clusters of ribosomes and rough endoplasmic seen in neuron cell bodies is called Nissl, Nissl bodies or Nissl substance. 
• The terminal bouton is the end portion of an axon. 
• It is also called an axon terminal or end bulb. 
• The terminal bouton will be associated with another neuron in a synapse.
• 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.
• Both motor neurons and interneurons are multipolar.
• The meninges are composed of the three connective tissue covers which surround the brain and spinal cord. 
• White matter is myelinated nerve fibers.
• Gray matter is essentially neuron cell bodies and associated dendrites or unmyelinated axons. 
• Nodes of Ranvier are the gaps that occur in the myelin sheath. 
• Neurofilaments are a type of intermediate filaments seen in neurons which provide rigidity and tensile strength.
• The meninges cover the brain and spinal cord. 
• There are three: dura mater, arachnoid, and pia mater.
• The dura mater is the outer meninx. 
• The dura mater is composed of dense irregular connective tissue.
• The arachnoid is made of a delicate spider web like connective tissue.
• The pia mater is the innermost meninx. 
• It covers the brain intimately.
• A group of fibers traveling together to a destination is a tract. 
• Islets of Langerhans are seen in the pancreas. 
• Soma is another term for a neuron cell body. 
• The outer part of the brain is gray matter called the cortex. 
• The conglomerations of gray matter deep within the cerebrum and cerebellum are called nuclei.
• Neuroglia are the supporting cells of the central nervous system. 
• Sometimes, neuroglia called glial cells or glia. 
• Astrocytes, ependymal cells, oligodendrocytes, and microglia are all neuroglia.
• Of the neuroglia cells, astrocytes are the most abundant and the largest. 
• These are star shaped cells involved in the blood brain barrier.
• Ependymal cells line the ventricles and spinal canal.
• Oligodendrocytes form myelin in the central nervous system.
• Microglia are the central nervous system macrophages.
• Schwann cells are seen in the peripheral nervous system and are not considered neuroglia.