Biochemistry NBDE (Hormones and misc.)

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  1. Al of the major anterior pituitary hormones, EXCEPT for growth hormones exert their principal effects by stimulating target glands, including thyroid gland, adrenal cortex, ovaries, testicles and mammary glands.

    Growth hormone, in contrast to other hormones, does NOT function through a target gland but exerts its effects directly on all or almost all tissues of the body.

    -1st true, second false
    -2nd false, first true
    -both true
    -both false
    • Both statements are true
    • Growth hormone (somatotropic hormone or somatotropin, protein with 191 AA synthesized by cells called somatotropes
    • Major target of GH is the LIVER, somatomedins cause bone growth.
    • GH causes, increased rate of protein synthesis, increased metabolism of Fatty acids from adipose, and increased FA in the blood and use of FA for energy. Decreased glucose utilization in the body, conserves carbs.
    • GH secretion stimulators: Exercise, sex hormones, deep sleep, stress, trauma, excitement, fasting, hypoglycemia, decreased blood free FA
    • GH secretion inhibitors: hyperglycemia, aging, obesity, increased blood free FA
  2. Testosterone and pituitary FSH are required for normal sperm production

    Many cells express the androgen receptor and the FSH receptor

    -1st true, second false
    -2nd false, first true
    -both true
    -both false
    • 1st true, second false, both are anterior pituitary hormones, but only the Sertoli cells  can express the androgen receptor and the FSH receptors, so these hormones regulate spermatogenesis indirectly through their actions on the Sertoli cells.
    • Thyrois stimulating hormone (TSH): thyroid gland, synthesis and secretion of thyroid hormone
    • Follice stimulating hormone (FSH): Ovary and Testis simulates growth of graagian follicles and estrogen secretion, sperm maturation
    • Luteinizing hormone: Ovary and testes, stimulates ovulation, forms corpus luteum, estrogen and progesterone, synthesis and secretion of testosterone
    • Growth hormone: Bone, stimulates protein synthesis and overall growth
    • Prolactin: Mammary glands, stimulates milk production and breast development
    • Adrenocorticotropic hormone: Adrenal cortex, synthesis and secretion of adrenal cortical hormones
    • Melanocyte stimulating hormone: Skin, melanin synthesis
    • Oxytocin (posterior pituitary): mammary glands, uterine smooth muscle, milk ejection and uterine contraction
    • Antidiuteric hormone (posterior pituitary): Kidney tubules, stimulates  water reabsorption, renal collecting ducts
  3. All of the following hormones use the adenylyl cyclase-cAMP second messenger system EXCEPT one. Which is the exception?

    -Adrenocorticotropic hormone (ACTH)
    -Thyroid releasing hormone
    • Thyroid releasing hormone
    • Second messengers: small, diffusible molecules that mediate intracellular effects of hormones and intervene between the original message (neurotransmitter or hormone) and the ultimate effect on the cell.
    • cAMP is synthesized from adenosine triphosphate (ATP) by adenylate cyclase
    • cAMP is degraded by a group of enzymes that are collectively known as phosphodiesterases
    • Most important target of cAMP is protein kinase A
  4. Which of the following is the best-known stimuli for increasing the rate of thyroid stimulating hormone (TSH) secretion by the anterior pituitary gland?

    - exposure to heat
    - exposure to cold
    - exposure to stress
    - exposure to relaxation
    • Exposure to cold
    • TSH controls the rate of secretion of thyroxine and triiodothyronine (control the rates of most chemical reactions in cells) from thyrotropes (cells of the anterior pituitary gland). 
    • TSH is stimulated by TRH
    • Hyperthyroidism (Graves' disease, Toxic Goiter, Thyrotixicosis): Entire thyroid gland is hyperplastic, usually with low to none TSH concentrations.
    • Hypothyroidism (Myxedema in adults and Cretinism in children): Decreased serum free T4 and increased serum TSH.
  5. Releasing hormones are synthesized in the:

    - Posterior pituitary
    - Hypothalamus
    - Anterior pituitary
    - Ovary
    • Hypothalamus
    • Releasing hormones are those that stimulate the secretion of other hormones
    • Secretions of the anterior pituitary are controlled by hypothalamic releasing and inhibitory hormones (factors).
    • Hormones of the Posterior pituitary (ADH and oxytocin) are synthesized in neuroendocrine cells. They are stored in nerve terminals located in neurohypophysis (posterior pituitary)
    • Examples: Prolactin releasing hormone, prolactin inhibiting hormone, corticotropin releasing hormone...
  6. ADH is formed primarily in the paraventricular nuclei and oxytocin is formed primarily in the supraoptic nuclei of the hypothalamus.

    ADH and oxytocin are secreted by the posterior pituitary.

    - first is true, second is false
    - second is true, first is false
    - both are true
    - both are false
    • Second is true, first is false
    • ADH (vasopressin) is formed primarily in the supraoptic nuclei and oxytocin in the paraventricular nuclei of the hypothalamus.
    • ADH acts on the kidneys to regulate the volume and osmolarity of urine, ADH decreases the production of urine by increasing the reabsorption of water by the renal tubules. Without ADH there would be extreme loss of water into the urine.
    • Oxytocin is secreted by the posterior pituitary in response to dilation of cervix and suckling, cases ejection of milk. Also causes positive feedback mechanism to push fetus against cervical opening.
  7. All of the following factors and conditions decrease insulin secretion, except one?

    - decreased blood glucose
    - fasting
    - Somatostatin
    - increased blood free fatty acids
    - alpha-adrenergic activity
    • Increased blood free fatty acids, increases secretion.
    • Insulin is the primary anabolic hormone responsible for the upper limit of glucose and free fatty acid blood levels, it achieves this by promoting glucose uptake and utilization by the muscle and adipose tissue.
    • Insulin is secreted by the beta cells in the islets of Langerhans of the pancreas. Major stimuli for insulin secretion includes increased serum glucose and some amino acids (arginine and lysine)
    • Insulin promotes use of carbs for energy and depresses the use of Fats, lack of insulin does the opposite (does not use brain tissue).
    • Clinical manifestations of Hypoglycemia: hunger, shakiness, perspiration, dizziness, confusion, lightheadedness, sleepiness, weakness and can result in seizure
  8. Glucagon, a hormone secreted by the alpha cells of the islets of Langerhans when blood glucose concentration falls, has several functions that are diametrically opposed to those of insulin.

    The most important function of glucagon is to increase the blood glucose concentration, an effect that is exactly the opposite that of insulin.

    - first is true, second is fale
    - first is false, second is true
    - both are true
    - both are false
    Both are true, Glucagon is the primary "counterregulatory" hormone that increases blood glucose levels through its effects on the liver glucose output.

    Glucagon release by alpha cells (in islets of Langerhans of pancreas) is promoted by: 1. Fall in blood glucose level (hypoglycemia) THIS IS THE MOST POTENT FACTOR 2. Sympathetic stimulation 3. increased level of amino acids ARGININE AND ALANINE in blood plasma (in this case glucagon and insulin act the same) 4. circulating catecholamines via beta2 adrenergic receptors.

    Factors that decrease glucagon: Rise in blood glucose level, insulin, free fatty acids, ketoacids and Somatostatin (aka, growth hormone inhibitory hormone, which also depresses insulin.)
  9. As the acidic stomach contents pass into the small intestine, the low pH triggers secretion of the hormone ______ into the blood.

    - Cholecystokinin
    - Gastric inhibitory peptide
    - Gastrin
    - secretin
    • Secretin, one of the hormones that control the GI secretion and the motility of the GI tract. First GI hormone discovered and secreted by "s" cells in he mucosa of the duodenum in response to acidic gastric juice emptying into the duodenum form the stomach. Secretin stimulates release of bicarbonate base from the pancreas to neutralize acid.
    • It inhibits stomach motility
    • Stimulates pancreatic duct cells to secrete bicarbonate ion fluid.
    • Stimulates secretion of bile from gallbladder
    • Cholecystokinin: facilitates digestion in small intestine, secreted by "I" cells in mucosa of duodenum and jejunum mainly in response to digestive products of fat, fatty acids and monoglycerides in the intestinal contents. This hormone contracts gallbladder explilling bile into small intestine, Also inhibits stomach contraction
    • Gastric inhibitory peptide (GIP): secreted by the mucosa of the upper small intestine mainly in response to fatty acids and amino acids and to a lesser extent carbs.
    • Gastrin: is a major physiological regulator of the gastric acid secretion. Secreted by the "G" cells of the antrum of the stomach in response to stimuli associated with ingestion of a meal.
  10. The enterogastric reflex, which is initiated when the duodenum fills with ______, inhibits the "pyloric pump" thereby inhibiting gastric motility and emptying.

    - bicarbonate
    - acid chyme
    - enkephalins
    - water
    • Acid chyme, as it enters the duodenum, decreases the pH and inhibits Gastrin secretion, and causes stop signals in the duodenum called enterogastrones (cholecystokinin (CCK, the most important stop signal), secretin and gastric inhibitory peptide (GIP). This allows time for digestive process to proceed before receiving more chyme (semifluid mass of partly digested food from the stomach to the duodenum).
    • The enterogastric reflex: also reduces motility and forcefully closes the pylotic sphincter. As the chyme is removed the pH increases and Gastrin and to "go" signals resumes. This continues until the stomach is empty.
    • Enterogastrones are released by the small intestine in response to the acidity of the duodenal chyme and the presence of amino acids and free fatty acids in the chyme.
  11. All of the following statements concerning aldosterone are true except one, which is the exception?

    Causes Na retention
    Causes K excretion
    Renin controls it
    Acts at the distal tube
    Is produced in the kidney
    • Is produced in the kidney (it is actually produced in the adrenal cortex)
    • Aldosterone: the principal mineralcorticoid secreted by cells located in zona glumerulosa of the adrenal cortex. It promotes resorption of sodium into the blood from the glomerular cortex. The potassium is lost in the urine. It also produces cortisol.
    • The target of aldosterone is in the distal tube of kidney where it stimulates exchange of NA and K with 2 physiologic effects. 1) increased resorption of sodium and water (where it is decreased under aldosterone stimulation. 2) Increased renal excretion of K
    • 2 significant regulators of aldosterone: concentration of potassium ion and angiotensin II (stimulates aldosterone secretion with renin-aldosterone system)
    • Major inhibitory signal is ANO (atrial natriuretic peptide)
    • Addisons disease: adrenocortical insufficiency, symptoms include, hyperpigmentation, muscle weakness, anorexia, hypoglycemia, hyperkalemic acidosis and hypotension
  12. Oral contraceptives work by:

    - inhibiting follicle formation by eliminating the LH surge
    - Inhibiting ovulation by eliminating the LH surge
    - Inhibiting follicle formation by elimination the FSH surge
    - Inhibiting ovulation by eliminating the FSH surge
    • Inhibiting ovulation by eliminating the LH surge
    • The synthetic estrogen-like or progesterone-like hormones in "the pill" prevent the rise in luteinizing hormone bcuz the hypothalamus will fail to secrete the normal surge of LH from the anterior pituitary gland and prevents ovulation.
    • Synthetic estrogen and progestins are better bcuz they are not destroyed by the liver in a short time like their natural counterparts.
  13. Which of the following is NOT found in the thyroid?

    • TRH, Thyrotropin-releasing hormone is released by the hypothalamus that communicates with the pituitary gland and stimulates release of Thyroid-stimulating hormone (TSH)
    • Follicular cells of the thyroid gland synthesize thyroglobulin containing tyrosine, here the iodinated molecules bind and form triiodothyronine (T3) and thyroxine (T4).
    • Functions: important for growth and development (especially brain), affect metabolic processes and the metabolic rate, increase oxygen consumption and heat production.
    • A dietary iodine deficiency will increase secretion of thyroglobulin (as opposed to T3, T4 or TSH)
  14. The catecholamines are synthesized from:

    - Alanine
    - Tyrosine
    - Proline
    - Arginine
    • Tyrosine, water soluble compounds like epinephrine and norepinephrine are catecholamines and come from Tyrosine.
    • Norepinephrine can be released in 2 ways: (1) by the adrenal medulla into the blood (effects are more widespread) (2) directly into an organ by postgangliotic sympathetic (adrenergic) neuron that stores norepinephrine
    • Outside of the nervous system norepinephrine and epinephrine act as regulators of carbohydrates and lipid metabolism.
  15. All of the following are affected by epinephrine and/or norepinephrine EXCEPT one. Which is the exception?

    - Blood glucose
    - Total peripheral resistance
    - Heart rate
    - Kidney function
    • Kidney function, is not affected
    • Adrenal medulla is a specialized ganglion of the sympathetic nervous system. Preganglionic fibers synapse directly on Chromaffin cells and secrete epinephrine (80%) and norepinephrine (20%) into the circulation, both are synthesized from tyrosine.
    • Epinephrine: stimulates glycogenolysis and gluconeogenesis (which raise blood sugar levels) and lipolysis. Increases rate, force and amplitude of heartbeat. constricts blood vessels, Dilates bronchioles in lungs and vessels in skeletal muscle, relaxes bronchiolar smooth muscle. Activates muscle glycogen phosphorylase
    • Norepinephrine: Increases heart rate and force. Promotes lipolysis, constricts blood vessels in all areas of the body thus increasing peripheral resistance.
  16. Parathyroid hormone causes which of the following to occur?

    - Removal of Ca via the kidney
    - Removal of Ca from bone
    - Removal of Ca via the GI system
    - None of the above
    • Removal of Ca from bone, PTH secreted in response to decreased plasma-calcium levels.
    • Plasma calcium levels control PTH secretion.
    • PTH: 1. removes calcium storage from bones 2. decreases calcium excretion in kidneys (increases phosphate excretion) 3. Increases Ca absorption in GI
    • Hyperparathyroidism: (von Recklinghausen's disease, causes extensive bone decalcification. High calclium, low phosphate blood levels. Muscle weakness
    • Hypoparathyroidism: (tetany) decreased bone resorption, increased renal phosphate reabsorption. decreased production of vit. D. Decrease serum calcium and increase serum phosphate.
  17. Which of the following hormones secretion is stimulated by stomach distention?

    -Cholecystokinin (CKK)
    -Gastrin inhibitory peptide (GIP)
    -All of the above
    • Gastrin, is a major regulator of gastric acid secretion. Synthesized in G cells (in antrum region of the stomach). Stimulates acid secretion, growth of gastric mucosa. hypergastrinemia causes Zollinger-Ellison syndrome.
    • Cholecystokinin (CKK): made in "I cells" of duodenum and jejunum. Contracts the gallbladder for bile to act on fat, fatty acids.
    • Secretin: made in "s cells" of the duodenum, principal stimulus for pancreas to secrete bicarbonate to neutralize acid.
    • Gastric inhibitory peptide (GIP): made in mucosa of upper intestine, acts on fatty acids and carbs to less extent. Mild effect on decreasing motor activity to allow emptying of contents into duodenum and proper digestion
  18. Which of the following gastrointestinal hormones seems to be the most potent in causing a moderate increase in insulin secretion?

    - Gastrin
    - Gastric inhibitory peptide (GIP)
    - Cholecystokinin (CKK)
    - Secretin
    • Gastric inhibitory peptide (GIP), causes and anticipatory spike in blood insulin in preparation for the meal to be absorbed (glucose and amino acids).
    • It is secreted by the mucosa of upper small intestine.
    • Other hormones that increase glucose; glucagon, growth hormone, cortisol and progesterone and estrogen (to a lesser extent). 
    • Type 2 diabetics are not responsive to GIP
  19. A tumor of the adrenal gland is causing your patient to conserve sodium in the renal tubules causing increased blood volume, pressure, and edema. Where is the location of this adenoma?

    Zona glorumerulosa of the adrenal cortex
    Zona fasciculata of the adrenal cortex
    Zona reticularis of the adrenal cortex
    Adrenal medulla
    • Zona glorumerulosa of the adrenal cortex
    • All steroid hormones are made from cholesterol
    • Mineralocorticoid aldosterone and glucocorticoids are collectively called corticosteroids

  20. Cortisol is the primary glucocorticoid produced by the adrenal cortex gland. Cortisol's principal physiological actions include all of the following EXCEPT?

    - Increase hepatic gluconeogenesis
    - Increase hepatic glycogenolysis
    - Increase protein catabolism
    - Stimulation of fat deposition and inhibition of lipolysis
    - Inhibit ACTH secretion (negative feedback mechanism)
    - Maintenance of blood pressure by sensitizing arterioles to the action of noradrenaline
    - Renal excretion
    • Stimulation of fat deposition and inhibition of lipolysis, this is false because clucocorticoids promote mobilization of fatty acids from adipose tissue and stimulate lipolysis.
    • Cushing's syndrome results from hypercortisolemia, if the cause is increased pituitary adrenocorticotropin secretion it is called Cushing's disease; centripetal fat distribution, muscle wasting, thin skin with abdominal striae, capillary fragility, insulin resistance, polycythemia.
  21. Which of the following is classified as a "stress hormone"?

    - growth hormone (GH)
    - thyroid-stimulating hormone (TSH)
    - adrenocorticotropic hormone (ACTH)
    - follicle-stimulating hormone (FSH)

    This hormone stimulates the excretion of:

    - Cortisol
    - Adrenalin
    - Aldosterone
    - Two of the above
    • adrenocorticotropic hormone (ACTH), Cortisol
    • ACTH secretion is controlled by the hypothalamus, to which the pituitary gland is attached. When the body is stressed, corticotropin-releasing hormone (CRH) produced by the hypothalamus travels to the anterior lobe of the pituitary where it inducs production and secretion of ACTH, this stimulates the adrenal cortex to make and secrete cortisol.
    • The secretion of aldosterone from the adrenal cortex is NOT induced by ACTH
    • ACTH deficiency is characterized by weight loss, lack of appetite (anorexia), weakness, nausea, vomiting and low blood pressure (symptoms of adrenal insufficiency)
  22. Cortisol (hydrocortisone) has a direct inhibitory effect on which two structures?

    - Adrenal cortex
    - hypothalamus
    - anterior pituitary gland
    - posterior pituitary gland
    • hypothalamus, anterior pituitary gland
    • Cortisol exerts inhibitory influence on both ACTH and CRH release by way of negative feedback.
    • Negative feedback: (more common than positive), is when the output of a pathway inhibits the input to the pathway (like a heater shutting off when your home reaches desired temperature, it works off of negative feedback)
    • Cortisol is the main glucocorticoid made and secreted by the cells of the zona fasciculata in the adrenal cortex. It allows glucagon and epinephrine to work more effectively at their target tissues, but antagonizes the actions of insulin. Glucocorticooids stimulate gluconeogenesis (synthesis of carbs from proteins and other substances) by the liver.
    • A patient taking cortisol for a long time can experience atrophy of the adrenal cortex due to the inhibition of ACTH production.
  23. The placenta secretes five hormones that are essential to pregnancy. Which of the following is NOT one of them?

    - Oxytocin
    - Progesterone
    - Relaxin
    - Estrogen
    - Human chorionic gonadotropin (hCG)
    - Human placental lactogen (hPL)
    • Oxytocin, which present at pregnancy is it not secreted by the placenta. 
    • hCG: promotes growth of corpus luteum and secretion of estrogens and progestrone by corpus luteum.
    • Estrogen: promotes development of female reproductive system
    • Relaxin: causes relaxation of pelvic ligaments for parturation, produced by placenta.
  24. Somatostatin acts by both endocrine and paracrine pathways to affect its target cells. A majority of the circulating somatostatin appears to come from the ____ and ______.

    - Gallbladder, large intestine
    - Pancreas, gastrointestinal tract
    - Stomach, adrenal medulla
    - Bladder, small intestine
    • Pancreas, gastrointestinal tract.
    • Somatostatin is produced by a broad range of tissues and acts by endocrine and paracrine pathways to effect target cells.
    • Inhibits the secretion of many other hormones"
    • Inhibits growth hormone from the pituitary gland, Depresses secretion of insulin and glucagon. Inhibits secretion of many other GI hormones (gastrin, CKK, secretin etc..)
  25. Prolactin is said to be under "predominant inhibitory control". Which of the following explains why?

    - In normal conditions, prolactin is constantly synthesized in the anterior pituitary. Only when prolactin is not needed does the inhibitory mechanism kick in.
    - In normal conditions. prolactin inhibitory factor is produced by the hypothalamus. Only when prolactin is needed does the lypothalamus stop synthesis and secretion.
    - In normal conditions, prolactin is synthesized by the hypothalamus. However, prolactin inhibitory hormone prevents the secretion unless prolactin is needed.
    - In normal conditions, prolactin inhibitory factor is produced by the anterior pituitary. Only when prolactin is needed does this stop and the ovaries are able to produce prolactin.
    • In normal conditions. prolactin inhibitory factor is produced by the hypothalamus. Only when prolactin is needed does the lypothalamus stop synthesis and secretion.
    • The hypothalamus synthesizes prolactin inhibitory factor (dopamine), this is why prolactin is under predominant inhibitory control by the hypothalamus.
    • Increases prolactin secretion: estrogen (pregnancy), sleep, breast-feeding, stress, TRH, dopamine antagonists (hypertension and antidepressants).
    • Decreases prolactin secretion: Dopamine (the major prolactin inhibiting factor), somatostatin, TSH and GH
  26. Steroid hormones are synthesized by a series of enzymatic modifications of:

    - Triiodothyronine
    - Thyroxine
    - Cholesterol
    - 5-Dihydrotestosterone
    • Cholesterol, the building block of steroid hormones and also a component of cell membrane (to allow hormones to enter cell)
    • Classes of steroid hormones
    • Androgens and Estrogens: from adrenal cortex and gonads, affect maturation and function of secondary sex organs (male)
    • Progestins: from ovaries and placenta, mediate menstrual cycle and pregnancy.
    • Mineralcorticoids: from adrenal cortex, maintain salt and water
    • Glucocorticoids: originate in adrenal cortex and affect metabolism, inflammation, stress.
  27. Calcitonin, a peptide hormone secreted by the thyroid gland, tends to decrease plasma calcium concentration.

    In general, calcitonin has effects opposite to those of parathyroid hormone

    - Which are true and false?
    • Both statements are true
    • 3 hormones (PTH, calcitriol and calcitonin) regulare the distribution of Ca between bone and ECF and thereby regulate plasma calcium.
    • PTH (parathyroid): increases calcium removal from storage in bone and absorption of calcium by intestines (increasing Ca levels)
    • Calcitonin (thyroid gland): increase calcium storage in bone, lowers Ca plasma levels. Its secretion is stimulated by hypercalcemia.
    • T3 and T4 (Thyroid gland): increase metabolism.
  28. The amount of T4 produced and released by the thyroid gland is controlled by the?

    - Hypothalamus
    - Medulla Oblongata
    - Parathyroid gland
    - Pituitary gland
    • Pituitary gland
    • Thyroid function is to take iodine and make thyroxine T4 and triiodothyronine T3, it is under the control of the pituitary gland. When the thyroid hormones are low, the pituitary gland produces TSH (thyroid stimulating hormone) to make more hormones.
    • The pituitary gland itself is regulated by the hypothalamus, who produces TRH (thyroid releasing hormone)
  29. On his 21st birthday, John celebrates with his first few beers. He notices (along with other symptoms of inebriation) that he has an increased need to urinate. This is a physiological caused by a decrease in the production of:

    - Oxytocin
    - Antidiuretic hormone (ADH)
    - Parathyroid hormone (PTH)
    - Aldosterone
    • Antidiuretic hormone (ADH) aka vasopressin, secreted from the posterior pituitary. Most important effect is to conserve body water.
    • Ethanol and caffeine decrease ADH while nicotine increases its release.
    • Sweating increases ADH while drinking a lot of water decreases ADH.
    • Hyposecretion of ADH and hypoactivity of posterior pituitary results in diabetes insipidus
  30. Polypeptide and protein hormones are stored in secretory vesicles until needed.

    Steroid hormones are usually synthesized from cholesterol and are not stored.

    -Which are true or false?
    • Both statements are true
    • Proteins and polypeptides are secreted by the anterior, posterior (ADH and oxytocin) pituitary gland, the pancreas (insulin and glucagon), parathyroid (PTH) and many others
    • Steroids are secreted by the adrenal cortex (cortisol and aldosterone), the ovaries, the testis and the placenta
    • Derivatives of the amino acid tyrosine, secreted by the thyroid (T3 and T4) and the adrenal medullae (epinephrine and norepinephrine)
  31. Which of the following cells has a resting potential?

    - Cardiac muscle cells
    - Nerurons
    - Histiocytes
    - Two of the above
    - All of the above
    • All of the above
    • All cells (not just excitable cells) have resting potential.
    • Excitable cells include neurons (action potential is called nerve impulse) and muscle cells.
  32. All of the following statements are true, EXCEPT?

    - Peripheral nerve fibers can sometimes regenerate if the soma (cell body) is not damaged and some of the neurilemma remains intact
    -The neurilemma forms a regeneration tube through which the growing axon re-establishes its original connection
    - If the nerve originally led to a skeletal muscle, the muscle atrophies in the absence of innervation but regrows when the connection is re-established.
    - Nerve fibers of the CNS (brain and spinal cord) posses the thickest neurilemma
    • Nerve fibers of the CNS (brain and spinal cord) posses the thickest neurilemma, this is FALSE; nerve fibers of the CNS are NOT enclosed by a neurilemma, this is why regeneration of severed axons is more difficult in the CNS (brain and spinal cord)
    • Neurilemma: also called "sheath of Schwann" is a thin membrane spirally enwrapping the myelin layers of certain fibers especially those of peripheral nerves or axons of certain unmyelinated nerve fibers.
    • ALL axons of the PNS have a sheath of Schwann cells around them and when it is wrapped successfully it is called a myelin sheath.
    • * Right sided lesions of spinal cord result in loss of motor activity on the same (ipsilateral) side and pain and temperature sensation on the opposite (contralateral) side.
  33. The primary action of local anesthetics in producing a conduction block is to decrease the permeability of the ion channels to:

    - Calcium ions
    - Chloride ions
    - Potassium ions
    - Sodium ions
    • Sodium Ions; Local anesthetics selectively inhibit the peak permeability of sodium. 
    • Local anesthetics reversibly block nerve impulse conduction and produce reversible loss of sensation at their administration site. The site of action of Local anesthetics is the lipoprotein sheath of the nerves.
    • Potassium, calcium and chloride conductances remain unchanged.
  34. The fasciculi gracilis and the cuneatus are the:

    - Largest ascending tracts of the spinal cord
    - Largest descending tracts of the spinal cord
    - Smallest ascending tracts of the spinal cord
    - Smallest descending tracts of the spinal cord
    • Largest ascending tracts of the spinal cord
    • The white matter of the spinal cord contains tracts that travel up and down the cord.
    • Ascending tracts are sensory (travel towards the bran), Descending tracts are motor
    • Sensory tracts begin with "spino-" and end in the part of the brain where it leads (spinothalamic)
    • Motor tracts begin with a part of the brain
  35. Which of the following characteristics are shared by simple and facilitated diffusion of glucose?

    - It is saturable
    - Requires metabolic energy
    - Occurs down an electrochemical gradient
    - Require a Na gradient
    • Occurs down an electrochemical gradient
    • Both types of transport occur down an electrochemical gradient (downhill and do NOT require metabolic energy).
    • Processes by which substances are transferred across cell membranes.
    • Diffusion: molecules spread from areas of high concentration to low concentration. (oxygen centers in this manner). They want to reach equilibrium.
    • Osmosis: a type of diffusion but only including the movement of water across a membrane. (in both Osmosis and diffusion, no energy is required)
    • Facilitated diffusion: substance passes through membrane with the help of integral membrane protein (who travels through diffusion)
    • Active transport: pumping of molecules or ions through a membrane against their concentration gradient. Using ATP.
  36. Which of the following patients has the least chance of edema formation?

    - A patient with inflammation
    - A patient who is standing
    - A patient with venous constriction
    - A patient with arteriolar constriction
    • A patient with arteriolar constriction
    • Constriction of arterioles causes decreased capillary hydrostatic pressure and a decreased net pressure overall.
    • Arteriolar dilation increases the likelihood of edema formation along with increased capillary pressure, decreased plasma colloid osmotic pressure, increased interstitial fluid colloid osmotic pressure and increased capillary permeability.
    • Edema: occurs when the volume of interstitial fluid exceeds the capacity of the lymphatics to return the fluid to the circulation.
  37. Match the scenario to the solution options:


    -A solution that when placed on the outside of the cell will cause osmosis out of the cell.
    -A solution that when placed outside of the cell wall will cause osmosis into the cell
    -A solution that when placed on the outside of the cell will not cause osmosis.
    • Isotonic/A solution that when placed on the outside of the cell will not cause osmosis.
    • Hypotonic/A solution that when placed outside of the cell wall will cause osmosis into the cell
    • Hypertonic/A solution that when placed on the outside of the cell will cause osmosis out of the cell.
  38. Which of the following is NOT an oncogene?

    - HER-2/neu
    - ras
    - nyc
    - src
    - CAAT
    • CAAT, is the binding site for RNA transcription factors.
    • Oncogene: is defective gene involved in triggering cancer growth
  39. Which of the following makes up most of the organic component of bone?

    - Collagen secreted by osteoblasts
    - Glycosaminoglycans secreted by osteoblasts
    - Collagen secreted by osteocytes
    - Glycosaminoglycans secreted by osteocytes
    • Collagen secreted by osteoblasts, bone matrix is made up of mostly type 1 collagen. Osteoblasts make a protein mixture called osteoid which then mineralizes to become bone.
    • Intracellular matrix of bone: contains organic components (glycosaminoglycans in ground substance and collagen fibers) and inorganic salts (calcium phosphate in the form of highly insoluble crystals of hydroxyapatite).
    • Bone if an important calcium reservoir
    • Common GAGs present in intercellular matrix of bone is hyaluronic acid and chondroitin sulfate.
    • Age, race and gender affect bone mass (blacks are denser than whites, men are denser than women, young are denser than old).
  40. All of the following bonds are considered weak bonds with the exception of:

    - Hydrogen bonds
    - Ionic bonds
    - Covalent bonds
    - van der Waals forces

    Weak bonds are involved in all of the following EXCEPT one:

    - secondary structure of proteins
    - cell membrane
    - dsDNA structure
    - Amino acid linkage
    • Covalent bonds (strongest type of chemical bond), amino acid linkage 
    • Weak bonds are easily broken, but are important in helping determine shape of biological molecules, stabilizing the secondary structure of proteins. (individually weak, but collectively strong.
  41. The pitch of a sound is related to which of the characteristics of the sound wave?

    - Amplitude of the sound wave
    - Frequency of the sound wave
    - Superimposed wave
    - Secondary waves
    - Length of sound wave
    • Frequency of the sound wave, it is measures in Hz.
    • Loudness of a sound is related to intensity and amplitude of the wave. Intensity is measured in dB (decibels) 
    • The timbre or quality of the sound is related to the presence of additional sound-wave frequencies  superimposed.
  42. The major intracellular cation is:

    - Sodium
    - Potassium
    - Magnesium
    - Chromium
    • Potassium
    • Intracellular fluid: 2/3 of the body's water. Primarily a solution of potassium and organic anions, proteins, etc... Not homogeneous, different throughout.
    • Extracellular fluid: 1/3 of the bodies water. Primarily NaCl and NaHCO3 solution. Divided into 3 subcompartments; 1. Interstitial fluid 2. Plasma. 3. Transcellular fluid
    • 60-40-20 Rule. If the body is 60% water, 40% is ICF and 20% is ECF.
  43. When the ambient temperature is above the body temperature, which heat transfer mechanism(s) is (are) used by the body to transfer energy from the body to the environment?

    - Radiation
    - Conduction
    - Convection
    - Evaporation of perspiration
    - All of the above
    • Evaporation of perspiration
    • Radiation, conduction and convection all transfer head into the body rather than out.
    • Ambient temperature the body can handle and thermo-regulate is between 68F and 130F
    • Temperature is regulated by nerual feedback mechanisms that operate through the hypothalamus.
    • Radiation is heat transfer by the emission of electromagnetic waves that carry energy away from the emitting object, Conduction is heat transfer by means of molecular agitation. Convection is heat transfer by fluid as air or water.
    • Shivering is the most potent mechanism for increasing heat.
  44. Which of the following solutions has an osmotic pressure different from the other two solutions?

    - 1 M glucose
    - 1 M sodium chloride
    - 1 M potassium chloride
    - They all have the same osmotic pressure
    • 1 M glucose
    • The osmotic pressure depends on the number of solute particles present and not on their various properties.
    • Different between osmolarity and tonicity, is that tonicity is a measure of impermeable solutes , osmolarity is the measure of all solutes.
  45. Which of the following statements concerning the two principal laws of thermodynamics is false?

    - They apply only to closed systems, that is, entities within which there can be no loss of energy or of mass.
    - The first law says that the total quantity of energy in the universe remains constant (this is the principle of the conservation of energy)
    - The second law states that the quality of this energy is degraded irreversibly (this is the principle of the degradation of energy)
    - The second law, known as Carnot's principle, is controlled by the concept of entropy
    - The two laws describe the concept that Delta G is positive in an exergonic reaction.
    • The two laws describe the concept that Delta G is positive in an exergonic reaction.
    • Heat bring a form of energy is subject to the principle of energy conservation (first law of thermodynamics), energy in a closed system is conserved.
    • Heat being a form of energy can be transformed, flow, converted but with disorder, Entropy measure of randomness or disorder in a system.
  46. Isotopes of an element:

    - Have different chemical properties but the same weights
    - Have the same chemical properties but in different weights
    - Have different chemical properties and weights
    - Have the same chemical properties and weights
    • Have the same chemical properties but in different weights
    • Isotopes are radioactive forms of an element that are the same in protons , but differ in the number of neutrons.
    • Radioactive forms of isotopes are often used as tracers in medical radiography.
  47. Growth and preparation of the chromosomes for replication occurs in which phase of the cell cycle?

    - G1
    - G0
    - S
    - G2
    - M
    • G1 - S - G- M
    • GAP1: Growth and preparation of chromosomes for replication
    • Synthesis: Synthesis of DNA (and centromeres)
    • GAP2: Preparation for mitosis
    • Mitosis: Division of cell occurs
  48. Which class of antibody constitutes about 75% of the antibodies of the normal person?

    - IgA
    - IgD
    - IgE
    - IgG
    - IgM
    • IgG, most common, secondary response (G-gestational) passes the placenta.
    • IgA: second most abundant, body secretions and protects surface tissues. Synthesized by plasma cells of mucus membranes, GI, respiratory and urinary tracts
    • IgM: Large antibody, PRIMARY RESPONSE, first to appear in body circulation when infected.
    • IgE: allerGEEEE (allergy), present in trace amounts, serum, mast cells, basophils, responsible for type 1 hypersensitivity reactions.
    • IgD: Receptor site on B lymphocytes, function is not fully understood.
    • GAMED: the order of most abundant
    • MADGE: Order of appearance
Card Set
Biochemistry NBDE (Hormones and misc.)
Hormones, nervous system and misc.
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