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107 Cards in this Set
- Front
- Back
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What is the portal system in relation to the hypothalamus?
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It is the system of blood vessels that link the hypothalamus and the anterior pituitary. The releasing and inhibiting hormones travel via this system.
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What is the exception to the negative feedback system of the hypothalamus/ pituitary?
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Growth hormone.
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What is another name for the posterior pituitary?
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Neurohypophysis
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What are the majority of cells found in the posterior pituitary (neurohypophysis)?
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Neuroglial
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What are 2 hormones found in the posterior pituitary?
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Vasopressin (ADH) and Oxytocin
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There are 2 hormones found in the posterior pituitary, but where are they actually synthesized? Be specific.
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Both synthesized in the hypothalamus. Vasopressin (ADH) produced in Supraoptic nucleus (SON) and Oxytocin produced in the Paraventricular nucleus.
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What is the nerve conduction between the hypothalamus and the pituitary gland?
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The body of the neurons are found in the hypothalamus and they extend into the posterior pituitary.
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What are the functions of Oxytocin?
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Necessary for milk release via stimulation of myoepithelial tissue. It is NOT involved in milk PRODUCTION. Just the release of milk. Also involved in uterine contraction, sperm motility, regulation of feeding. Also might possibly be involved in development of autism.
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What is myoepithelial tissue?
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Cells that look like muscle cells and surround ducts. As they contract, milk can be released.
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What is the process of the release of milk?
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When an infant suckles, free nerve endings send signal to brain that stimulates the posterior pituitary to release oxytocin. Oxytocin acts on the myoepithelial tissue which contracts and allows for the release of milk.
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How is oxytocin involved in uterine contractions?
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Involved during menses and parturition. In menses, with Prostaglandin F2alpha, it causes contraction which enhances the process that leads to sloughing of the endometrial lining and causes bleeding. It is unclear if oxytocin directly or PGF 2alpha is responsible for this process.
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How does ibuprophen help to relieve menstrual cramps?
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It inactivates Prostaglanding F2 alpha
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How is sperm motility influenced by oxytocin?
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Oxytocin is released (by the female) during intercourse which causes uterine contractions that pulls the sperm up. Because of this, even sperm w/out tails can possible still fertilize an egg (but this would be rare).
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What part of the sperm contains the chromosomes needed to make a diploid set of chromosomes with the egg?
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The nucleus in the head of the sperm. It contains half the chromosomes (haploid).
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How does the sperm penetrate the egg?
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The head (acrosomal body) contains enzymes that penetrate through the outside membranes of the egg. The only thing it deposits in the egg is the haploid nucleus.
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What is the function on the tail of the sperm? And what organelle is contained in it?
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Primary function of the tail is motility. The nucleus is located in the head. Only organelle found in the tail is mitochondria for energy.
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How is Oxytocin a regulator of feeding?
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In rats it is found that it causes them to stop feeding. In anorexia nervosa, in some cases we see high levels of oxytocin.
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What are the 2 main functions of Vasopressin (ADH)?
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Water conservation (kidney tubules) via cyclic AMP. Mild vasoconstrictor.
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What two types of hormones does the thyroid produce?
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T3 (triiodothyronin) and T4 (tetraiodothyronine)
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What is the middle portion of the Thyroid gland called?
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Isthmus. Translation: to bridge.
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How can you tell if the thyroid gland is active or not?
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When follicular cells are cuboidal, the gland is active. When follicular cells are columnar, the gland is inactive.
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What area of the thyroid is where the hormone is located?
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Colloid
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Why is it not apparent immediately if there is a problem with the production of thyroid hormones?
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Because the thyroid has a capacity to store up to a 3 months supply of hormone
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What is the vascularization of the thyroid and why is it so vascular?
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Per weight, it is the most vascularized tissue. 2 major arteries supply it and 2 major veins. It must clear (filters) iodine out of the circulation.
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What is the process of the thyroid clearing iodine from the circulation?
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Active process using ATP which makes it a slow process. Clearance of iodine from the thyroid is greater than the kidneys.
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What is the base structure of T4 and T3?
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Thyronine, which is 2 thyrosine molecules bound. Thyronine has a glycine side chain, but when 2 bound together, one of the glycines is cleaved off. (At this point, iodine is not attached)
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What is T4 stored bound to?
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Thyroglobulin molecule which is a large protein w/in colloidal space of follicles
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What does T4 need in order to have hormonal activity?
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Iodine
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If a person is producing a lot of thyroid hormone, how could you treat this?
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By blocking iodination. by doing that, it won't have its hormonal function.
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What is another name for T4 (tetraiodothyronine)?
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Thyroxine
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What is the biologically active form of thyroid hormone? How does it become that way?
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T3. In target cells, T4 is converted to T3 by deiodinase enzyme.
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What are the 5 functions of thyroxine (or rather the biologically active form: T3)?
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Increase in basic metabolic rate, protein synthesis, protein degredation, neuronal development and function of fetus, Increase in cardiac activity
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How does thyroxine cause an increase in basic metabolic rate?
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It targets the mitochondria
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How is it possible that thyroxine can cause both protein synthesis and protein degredation?
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When there is a normal level of thyroxine, it stimulates protein synthesis, but then the level of thyroxine is high, it causes degredation. May see muscle wasting in hyperthyroidism.
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How does T4 influence neuronal development and function of the fetus?
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Causes cretinism. The brain doesn't develop properly in utero or immediately after birth if the fetus is not receiving enough T4.
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How does thyroxine increase cardiac activity?
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It increases B receptors and increases activity of epinephrine and norepinephrine.
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What is a disease process associated with thyrotoxicosis?
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Graves Disease (auto immune). Immune attack is on the TSH receptor and mimics the affect of TSH. This stimulates the thyroid to produce excessive amounts of T4 (hyperthyroidism).
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In Graves Disease what kind of lab results would you expect to see?
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TSH would be low, TSH-RH low (because of negative feedback) and T4 would be high. The high T4 would cause the negative feedback to stop the production of TSH-RH and TSH.
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What is the most common cause of hypothyroidism?
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Iodine insufficiency
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What is hypertrophy of the thyroid called? How does this happen?
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Goiter. In both hyperthyroidism and hypothyroidism, there is often a continuous stimulation of the thyroid gland (leading to high levels of T4 in hyper or trying to compensate for low levels of T4 in hypo).
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How would one treat hypothyroidism?
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With iodine or with thyroxine
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Where are the parathyroid glands? What is their function?
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They are located on the posterior side of the thyroid gland. They control the amount of calcium in the blood and within the bones.
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What cells produce calcitonin?
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C cells
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What is the primary function of calcitonin in the blood?
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Decreases plasma calcium levels by depositing calcium in bone tissue which increases bone mineral density
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What 2 forms can calcium take?
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Free state: biologically active (ionized) - very small amount is in this state.
Bound calcium: not biologically active. The bulk of calcium are in this state - bound to proteins or other compounds |
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What is primary function of PTH in the blood?
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Increases plasma calcium by inducing resorption of bone tissue (decreases bone mineral density). In the circulation PTH and calcitonin have opposite effects.
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What synergistic function do PTH and calcitonin have? Where?
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They both induce absorption of calcium by the intestine and reabsorption by the kidney.
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What is the relationship between Vitamin D and PTH?
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Vitamin D promotes the absorption and use of calcium. PTH is involved in Vitamin D production. (calcitonin has no affect on vitamin D formation)
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What diseases' etiology is lack of Vitamin D?
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Rickets - does not allow for absorption of calcium in the intestines.
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What are the 5 main treatments for osteoporosis?
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Calcitonin therapy (derived from salmon -about 20x more potent than human), PTH, Diet and exercise (must be weight bearing exercises), bisphosphonates, SERM (selective estrogen receptor modulators): avoids affects of estrogen by mimicing estrogen.
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What is the best therapy for osteoporosis and only drug currently that causes new bone formation? Why is this counterintuitive?
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PTH. This is counterintuitive because the PTH we naturally make causes resorption of bone tissue
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How much of the pancreas is the Islets of Langerhans?
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2-5% of the total mass
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Are the islets of Langerhans endocrine or exocrine function?
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Endocrine
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What are the 4 types of cells in the Islets of Langerhans?
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Alpha, Beta, C cells and Delta cells
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What are the alpha cells of the islets of langerhans?
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Produce gucagon and found primarily arounPand the periphery
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What are the Beta cells of the islets of Langerhans?
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Produce insulin. Proinsulin is made then converted to insulin.
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What is the structure of insulin?
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A chain with 21 amino acids and B chain with 30 amino acids
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What are the C cells of the islets of Langerhans?
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Pancreatic polypeptide. They are distributed randomly and appear to have some sort of digestive function, but it is not well understood.
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What are the delta cells of the islets of Langerhans?
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Produce somatostatin. Inhibit the release of both glucagon and insulin. Located sporadically between alpha and beta cells.
Also located in the hypothalamus as growth hormone inhibiting hormone. |
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What are the 5 functions of insulin?
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Glycogenesis, Lipogenesis, Protein syntheses, Inhibition of glycogenolysis, lipolysis and protein degredation, Activates GLUT (1-5) which allow cells to pick up glucose.
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What is type I Diabetes Mellitus?
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Formerly juvenile onset DM. Insulin dependent diabetes mellitus. Ketosis prone, insulin therapy. This is an autoimmune disease. Cannot give hypoglycemic oral agents - need insulin so glucose can get into cells.
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What is type II Diabetes Mellitus?
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Formerly adult onset. Non insulin dependent DM. Non-ketosis. Diet and exercise and drug therapy: hypoglycemic agents, insulin therapy (sometimes combo).
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What is Gestational DM?
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Placental lactogen (anti-insulin). After pregnancy, significant increase risk of developing type II DM. Therapy is usually diet. If that doesn't work, must put on insulin therapy.
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In our country, what percentage of our population is overweight? Of that, how many obese? According to BMI
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2/3 population overweight. Half of that: obese
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What can happen to the insulin receptors in DMT2?
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Down regulation of the insulin receptor w/ excessive cellular glycogen deposition.
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How does down regulation of insulin receptors occur?
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As glucose enters the cells, it is converted to glycogen but only to a certain point. Once the cell is saturated, the insulin receptor is down regulated (internalized). At that point, no matter how much insulin, GLUTs won't be activated. Glucose in circulation rises.
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How does exercise attribute to the uptake of glucose into the cells?
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Glycogen gets converted back to glucose to be used for energy. The cell is no longer saturated, so the insulin receptor goes back to the surface and allows for more glucose to enter the cell.
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What are 4 pathologies related to diabetes mellitus?
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Neuropathy (major reason for amputations) - usually end stage, Nephropathy: loss of kidney function, Retinopathy: blindness, Cardiovascular disease.
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What are the different ranges for plasma glucose after overnight fasting and what does each range indicate?
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70-100 mg/dL: normal range
101-110: moderate risk for DM 111-125: high risk for DM >/=: DM |
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What is the Glucose tolerance test?
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Patient given specific amount of glucose in a drink. Blood sample taken before drinking, then every 30 min after drinking and glucose levels are measured. More accurate way of determining DM
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What type of hormones does the adrenal cortex produce primarily?
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Steroidal hormones
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What are the three zones of the adrenal cortex?
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Zona Glomerulosa, Zona Fasiculata, Zona Reticularis
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What does the Zona Glomerulosa produce primarily?
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Mineralcorticoids (aldosterone). Aldosterone is the only steroid that has an aldehyde attached.
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What does the Zona Fasiculata produce primarily?
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Glucocorticoids (cortisol or hydrocortisone)
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What does the Zona Reticularis produce primarily?
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Androgens
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What layer of the adrenal cortex, does ACTH act on? Stimulates what type of hormone?
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Acts on the zona fasiculata stimulating glucocorticoids.
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What is the function of glucocorticoids?
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Gluconeogenesis in the liver, glycogen synthesis by the liver, lipids and fatty acids released into blood by adipose cells, breakdown of skeletal muscle fiber, anti inflammatory / immunosuppressive activity (most important!!)
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What is gluconeogenesis (stimulated by glucocorticoids)?
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Conversion of non carbohydrates to carbohydrates in the liver. If you deplete all your glucose (i.e. during exercise) - a healthy person would still have a blood glucose of 70-100 because of gluconeogenesis breaking down proteins into carbos for energy.
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What function of glucocorticoids is a bad thing?
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Breakdown of skeletal muscle fiber proteins. Amino acids are taken to the liver and undergo gluconeogenesis to produce glucose and releases glucose into circulation.
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What is the most important function of glucocorticoids?
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Anti-inflammatory / immunosuppresive activity. Action is on nuclear factor: K beta. Also has an affect on different secretions of cytokines.
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What controls glucocorticoid levels?
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Negative feedback. MAKE SURE TO KNOW NEGATIVE FEEDBACK SYSTEM!!!
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What disease process is caused by the insufficient secretion of glucocortiocids?
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Addison's Disease
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What disease process is caused by excessive secretion of glucocorticoids?
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Cushings
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What is the basic structure that ALL steroids are derived from? How many carbons?
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Sterane. Will have a minimum of 17 carbons. See ABCD structure in notebook
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Why would cortisol have some similar functions to Aldosterone?
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They are both steroids so they share the same basic structure
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Where does spermatogenesis take place?
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Within the seminiferous tubules
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What are the cells between the seminiferous tubules and what do they do?
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Leydig cells. Responsible for producing testosterone. Without testosterone, there cannot be sperm production!
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What is the lack of sperm production called?
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Azoospermia
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Why does the mass of the testes decline with aging?
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Loss of Leydig cells over time = levels of testosterone delcine
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What are sertoli cells?
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Produce estrogen which is needed for proper development of sperm. Without estrogen, there CAN still be limited sperm production, but testosterone is absolutely necessary. Steroli cells also produce inhibin.
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What does inhibin (produced by Sertoli cells) do?
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Important for negative feedback
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What is the process of the maturity of sperm?
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Immature sperm cell starts as diploid 2N. As it matures, it undergoes reduction division (Meiosis) and goes from diploid to 2 haploid cells (1N). Those cells divide/ undergo mitosis and produce 4 sperms. (In the female, only one egg will make it in this process). This is strictly under hormonal control (primarily testosterone)
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Hormonally, what is the process of the maturity of sperm beginning at the brain in puberty?
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GnRH --> FSH/LH
FSH --> Sertoli cells (nurse cells) --> estrogen. LH --> Leydig cells --> Testosterone |
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What controls the amount of production of testosterone?
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Negative feedback mechanism.
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Until what age does the production of sperm occur?
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Throughout the entire lifetime. There is a lower production of sperm later in life, but it is still occuring.
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How do anabolic steroids mimic the affect of testosterone?
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Anabolic steroids bind on the same receptor in the negative feedback system as testosterone would. It fools the brain into thinking there is a high amount of testosterone and causes a negative feedback which leads to azoospermia.
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In the female reproductive system, what is the purpose of secretion of estrogen and progesterone?
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Secreted each month to rebuild endometrial lining.
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What happens to the endometrial lining if pregnancy does not occur?
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It is sloughed off. As endometrial lining has been built, if pregnancy doesn't occur, the negative feedback will decrease the amount of estrogen and progesterone which causes loss of endometrial lining. Estrogen and progesterone is needed to maintain the lining.
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How many eggs (on average) would a woman release in a lifetime?
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~500. If ovulation takes place over the course of ~40 years, and 1 egg is released each month
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What is the process of the egg being selected to be released during ovulation?
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20-24 eggs are selected initially, but only 1 will reach maturity. It will be dominant and secrete estrogen. The rest will atrophy. It is not known how the 1 is slected.
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What is progesterone's function in the female reproductive system?
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It is a potent inhibitor of uterine contraction. A significant amount of natural abortions occur due to low levels of progesterone.
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If pregnancy does not occur, what happens to the corpus luteum?
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It becomes scar tissue called corpora albicans. This is due to the decrease of LH levels due to negative feedback mechanism.
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What happens to the negative feedback system if pregnancy occurs?
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It still is a negative feedback system. LH and FSH levels go away, but in pregnancy, corpus luteum does not become corpora albicans. It stays as corpus luteum. This takes the place of LH because the early placenta makes HCG which maintains the integrity of the corpus luteum.
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Why does the corpus luteum need to be maintained during pregnancy?
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It helps to maintain high levels of estrogen and progesterone.
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Does corpus luteum maintain high levels of estrogen and progesterone throughout the entire pregnancy?
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No. Only during the first trimester. After the first trimester, the placenta is fully developed. Once developed, it can maintain the levels of estrogen and progesterone.
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What happens to progesterone levels at birth? What happens to oxytocin levels at birth?
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Progesterone levels decline! You don't want progesterone because it inhibits uterine contraction. Estrogen levels stay high. Oxytocin rises significantly because it helps to stimulate uterine contraction.
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How does the birth control pill prevent pregnancy?
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With exogenous high levels of estrogen and progesterone (via the pills), it stops the production of LH by the negative feedback system. Without LH, there can't be ovulation. Without ovulation, no pregnancy.
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