Histology concepts and applications

Skeletal Muscle Tissue Review

The functional unit of contraction in skeletal muscle is the sarcomere which is the smallest element of a muscle fiber.

The two principle contractile proteins that compose the functional unit of contraction are created by the interaction of actin and myosin.

Skeletal muscle is striated due to the structural organization of contractile protein within individual muscle cells.

Skeletal muscle is often referred to as voluntary muscle which attached to the bone and skin that needs voluntary movements like walking.

The site of close juxtaposition of an axon terminal with the muscle cell plasmalemma is the synapse.

The perimysium is a collagenous connective tissue layer that groups several muscle fibers into bundles called fascicli.

The epimysium is the connective tissue layer which surrounds the entire muscle and merges with connective tissue of tendons and aponeuroses.

Nervous Tissue Review

The primary unit of function in nervous tissue is the neuron

2. The axon hillock is the pale-staining region of the cell body from which the axon arises.

3. The support cell within the CNS is the Cytoplasmic Basophilia.

4. The oligodendrocyte is the myelin-forming cell in the central nervous system.

5. The endoneurium surrounds and protects the myelin sheath while a myelin sheath is a covering of fat that intermittently wrap around a single neuron to send a message quicker.

Endocrine Tissue Review

1. The thyroid gland is considered to be and endocrine organ because it secretes hormones.

2. The hormone secreted by the pituitary gland controls the synthesis and secretion of T3 and T4 (thyroxine) is the Thyroid Stimulating Hormone (TSH).

3. Calcitonin hormone regulates the blood calcium levels.

4. Corpora Lutea is responsible for producing estrogen.

5. The thickened endometrium is shed in a period of bleeding that is menstruation. The first day of bleeding is the start of a new cycle of endometrial proliferation.

6. Stratum Basalis is the source of cells to regenerate endometrium after menstruation.

7. A serosa is composed of a secretory epithelial layer known as mesothelium which is consists of a single layer of avascular flat nucleated cells and a connective tissue layer underneath which makes available the blood vessels and nerves for the overlying secretory cells.

8. It differs by serosa being a smooth membrane consisting of a thin layer of cells which excrete fluids and visceral peritoneum being a continuation of the parietal peritoneum reflected at various places.

9. Do the islets of Langerhans cells secrete their hormones into the same duct system used by the exocrine secretory cells?

Cardiovascular Tissue Review

1. Intercalated discs consist of adhering junctions into whom the contractile myofilaments are attached and gap junctions who allow passage of ions thereby establishing electrical connection between adjacent cells.

2. A functional syncytium a single, enormous muscle cell.

3. The fascia adherens component.

4. The aorta has a tunica media dominated by elastic tissue. The elasticity conferred by elastin allows these elastic arteries to smooth out the sharp changes in blood pressure resulting from the pumping heart.

5. An artery would have a larger lumen than its corresponding vein. With such relatively thin walls, veins tend to appear flattened or collapsed in contrast to arteries, which tend to appear more round.

6. The tunica media and tunica adventitia would not be presents in a capillary for the reason that

Respiratory Tissue Review

1. Respiratory Epithelium contains serous and mucous glands, these reflect the functions of the nasal mucosa, to warm and humidify the incoming air.

2. Gas exchange occur in bronchi since it occurs in the capillaries which are found in the alveoli sacs

3. The primary functional unit of the lung is the acinus which includes all of the structures of the respiratory portion of the lung namely the respiratory bronchiole, the alveolar ducts and alveolar sacs.

4. Smooth muscle is not present in the alveolar wall for the reason that it would interfere with gas exchange.

5. The three basic components of the air-blood barrier are the type I epithelial cell, capillary endothelial cell and the fused basal laminae of type I cell and the endothelial cell.

Digestive Tissue Review

1. Salivary glands are exocrine glands

2. Serous cells produce a thin and watery salivary secretion.

3. The adventitia is a very pale connective tissue and unlike a serosa, an adventitia just merges with surrounding connective tissue and has no finished edge of mesothelium.