Can anyone help answer the unanswered questions and check the rest.

Exercise H:  Histology Tutorial
Assignment Due:  Extra Credit

Student instructions:  Follow the step-by-step instructions for this exercise found in your text and record your answers in the spaces below.  Submit this completed document by the last official day of the semester.

Skeletal Muscle Tissue Review

1.   What is the functional unit of contraction in skeletal muscle? Sarcomeres.
2.   What are the two principle contractile proteins that compose the functional unit of contraction? Myosin and actin.
3.   What is the specific relationship of the functional unit of contraction to the striated appearance of a skeletal muscle fiber? The organization of contractile proteins into a regular end-to-end repeating pattern of sacromeres along the length of each cell accounts for the striated, or striped, appearance of skeletal muscle in longitudinal section.
4.   Would you characterize skeletal muscle as voluntary or involuntary? Skeletal muscles are voluntary because you have the will and intention to move them.
5.   Name the site of close juxtaposition of an axon terminal with the muscle cell plasmalemma. The motor end-plate.
6.   What is the name of the loose areolar connective tissue covering of an individual muscle fiber? Each muscles fibers (cells) are covered with Epimyseum. And these muscles fibers are bundled up together to form Fascicles which are covered by perimysium.
7.   The perimysium is a collagenous connective tissue layer that groups several muscle fibers into bundles called: Epimysium surrounds the muscle, Perimysium surrounds fascicles and endomysium surrounds myofibers.
8.   Which connective tissue layer surrounds the entire muscle and merges with connective tissue of tendons and aponeuroses? Epimysium.

Nervous Tissue Review

1.   What is the primary unit of function in nervous tissue? Neuron
2.   Name the pale-staining region of the cell body from which the axon arises. Nucleus
3.   What is the general name for all support cells within the CNS? Neuroglial (glial) cells
4.   Name the specific myelinating cell of the CNS. Oligodendrycytes are the cells in CNS.
5.   What is the relationship of the endoneurium to the myelin sheath? The endoneurium surrounds and protects the myelin sheath.



Endocrine Tissue Review

1.   Why is the thyroid gland considered to be an endocrine organ? Thyroid gland secretes a hormone called thyroxin. Since the organs secreting hormones are a part of endocrine system thyroid gland is an endocrine organ.
2.   What hormone secreted by the pituitary gland controls the synthesis and secretion of T3 and T4 (thyroxine)? Thyroid stimulating hormone (TSH). It triggers the thyroid to syntheses T3 and T4.
3.   What is the function of calcitonin?
4.   Which cells of the ovarian follicle secrete estrogen? Granulosa cells.
5.   Which layer of the endometrium is shed during the menstrual phase of the menstrual cycle? The lining of the uterine cavity is called the endometrium. It consists of the functional endometrium and the basal endometrium. Shedding of the functional endometrial lining in humans is responsible for menstrual bleeding.
6.   What is the function of the deep basal layer (stratum basalis) of the endometrium? To regenerate a new superficial layer of endometrium for each menstrual cycle.
7.   What comprises a serosa? Perimetrium.
8.   How does the serosa of the uterus, where present, differ from visceral peritoneum? The location. The Serosa is the outermost layer while the visceral peritoneum is the innermost layer.
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.   Which component of the intercalated disk is a strong intercellular junction that functions to keep cells from being pulled apart during contraction? Desmosomes.
2.   What is a functional syncytium? Cardiac muscle cells are mechanicall, chemically and electrically connected to one another. The entire tissue resembles a single enormous muscle cell and for this reason cardiac muscle has been called a functional syncytium. This is also true of a smooth muscle.
3.   Which component of the intercalated disk is a junction that provides the intercellular communication required for the myocardium to perform as a functional syncytium? Gap junctions.
4.   The tunica media of the aorta would have a much greater proportion of what type of tissue than a small artery? Elastic Fibers, the aorta has much more pressure exerted on its walls than small arteries. The elastic fibers allow it to handle the pressure and acts as a second pump when the heart is relaxing to keep blood flowing through the arterial system.
5.   In general, which vessel would have a larger lumen, an artery or its corresponding vein?
6.   Why would the tunica media and tunica adventitia not be present in a capillary? The capillaries are very thin and many times as few as one red blood cell wide, and only have enough room for a layer of endothelial tissue, in the form of the Tunica Intima.


Respiratory Tissue Review

1.   What are the primary functions of the respiratory epithelium? The primary functions of the respiratory epithelium are to humidify, filter and warm the incoming air during respiration.
2.   Why doesn’t gas exchange occur in bronchi? Because smooth muscle is present.
3.   What is the primary functional unit of the lung?
4.   The alveolar wall is very delicate and subject to collapse.  Why is there no smooth muscle present in its walls for support?
5.   What are the three basic components of the air-blood barrier? The alveolar, capillary walls and basal laminae.

Digestive Tissue Review

1.   Are salivary glands endocrine or exocrine glands?
2.   Which salivary secretions, mucus or serous, is more thin and watery in consistency? Serous
3.   Briefly explain the difference between an adventitia and a serosa. Serosa is a serous membrane that secretes serous fluid and adventitia does not.
4.   What is the function of the mucus secreted by surface mucous cells? They protect the inner stomach wall from acid and pepsin.
5.   Why is it important for the duodenum to add large quantities of mucus (from Brunner’s glands) to the partially digested food entering it from the stomach? Mucus protects the intestinal walls, binds fecal matter and helps control pH of contents.
6.   Why is it important to have an abundance of mucous goblet cells in the colon? Facilitates passage of material through the bowel.
7.   What general type of cell is the phagocytic Kupffer cell? The immune cell, white blood cell and macrophage.
8.   Blood in the portal vein flows directly from what organs? The hepatic portal vein carries blood from the small intestine to the liver.
9.   What is the function of bile in the digestive process?

Renal Tissue Review

1.   In which segment of the renal tubule does roughly 75-80% of reabsorption occur?
2.   How are proximal convoluted tubule (PCT) cells similar to enterocytes of the small intestine? They both act as to absorb water, salts, urea, vitamins and phosphates.
3.   What are the three layers through which the filtrate must pass starting from inside the glomerular capillary through to the urinary space? Glomerular Capillary Endothelium, Glomerular Basement Membrane and Visceral layer of Bowman’s Capsule.
4.   Under normal circumstances in a healthy individual, would red blood cells or any other cells be present in the renal filtrate? No, the blood in the urine would be present in case of urinary tract infection wich breaks down the kidnets.
5.   In addition to providing nutrients to the kidney tubules, what is one other function of the capillaries in the peritubular capillary bed?