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24 Cards in this Set
- Front
- Back
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Aldosterone exerts its effects on target cells by:
A. binding to a receptor at the cell surface, setting off a second-messenger cascade. B. diffusing into adrenal cortical cells, where it influences transcription of certain DNA sequences. C. flowing across the synapse, where it binds and initiates an action potential D. entering into target cells, where it increases the rate of production of sodium-potassium pump proteins. |
D is correct.
Aldosterone, as we can tell by its name, is a steroid (any hormone whose name ends in "sterone" or something similar is a steroid). This allows us to eliminate choice A, because steroid hormones do not need cell membrane receptors or second-messenger systems. They simply diffuse across the cell membrane. We can eliminate B because the adrenal cortex is aldosterone's source, not its target tissue. C describes events at a synapse. Aldosterone actually exerts its effect by doing what D says, increasing the production of sodium potassium pump proteins. |
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A patient develops an abdominal tumor resulting in the secretion of large quantities of aldosterone into the bloodstream. Which of the following will most likely occur?
A. Levels of renin secreted by the kidney will increase B. Levels of oxytocin secreted by the pituitary will increase C. Levels of aldosterone secreted by the adrenal cortex will decrease D. Levels of aldosterone secreted by the tumor will decrease. |
C is correct.
This is a negative feedback question. If another source of aldosterone exists in the body besides the adrenal cortex, negative feedback (through the renin-angiotensin system and increased blood pressure) would suppress the level of aldosterone secreted by the adrenal cortex. A is out because the leels of renin in the blood would decrease, not increase, aldosterone relase would increase blood pressure and renin is released in response to low blood pressure. Oxytocin plays no role in blood pressure (vasopresesin does) and would not be affected by this tumor. Now, to choose between C and D: we know that aldosterone from the adrenal cortex would respond to negative feedback, but we aren't sure whether the tumor would. At this point, we know enough to go with C. If we're sure C is a correct response, t hat must mean D is an incorrect response and we can eliminate it. In fact, this is a good choice because normally, hormone-secreting tumors will not respond to negative feedback. |
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Which of the following is true for all endocrine hormones?
A. They act through a second messenger system B. They bind to a protein receptor C. They dissolve in the blood D. They are derived from a protein precursor. |
B is correct.
All hormones bind to a protein receptor, whether at the cell membrane, in the cytoplasm, or in the nucleus of the cell. Steroids and thyroxine require a transport protein to dissolve in the aqueous solution of the blood. Steroids are derived from cholesterol, not protein precursors |
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All of the following act as second messengers for hormones EXCEPT:
A. cyclic AMP B. calmodulin C. acetylcholine D. cyclic GMP |
C is correct
Acytelcholine acts through a second messenger system and is not a second messenger itself. |
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Which of the following is true of all steroids?
A. The target cells of any steroid include every cell in the body B. Steroids bind to receptor proteins on the membrane of their target cells. C. Steroids are synthesized on the rough endoplasmic reticulum D. Steroids are lipid soluble |
D is correct.
Steroids are lipid soluble. Different steroids may have different target cells. For instance, estrogens are very selective while testosterone affects every or nearly every, cell in the body. Steroids act as the transcription level in the nucleus, and are synthesized by the smooth endoplasmic reticulum. |
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The pancreas is a unique organ because it has both exocrine and endocrine function. The exocrine function of the pancreas releases:
A. digestive enzymes straight into the blood B. digestive enzyme through a duct C. hormones straight into the blood D. hormones through a duct. |
B is correct.
Exocrine function refers to enzyme delivery through a duct |
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Most steroid hormones regulate enzymatic activity at the level of:
A. replication B. transcription C. translation D. the reaction |
B is correct
Steroids act at the level of transcription by regulating the amount of mRNA transcribed |
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Which of the following side-effects might be experienced by a patient who is administered a dose of thyroxine?
A. An increase in endogenous TSH production B. A decrease in endogenous TSH production C. An increase in endogenous thyroxine production D. A decrease in endogenous parathyroid hormone production |
B is correct
You should know that T3 and T4 (thyroxine) production are controlled by a negative feedback mechanism involving TSH (thyroid stimulating hormone) from the anterior pituitary; parathyroid hormone production is not be affected by thryoxine levels. |
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Sympathetic stimulation results in response most similar to release of which of the following hormones?
A. Insulin B. Acetylcholine C. Epinephrine D. Aldosterone |
C.
C is correct. Epinephrine release leads to "fight or flight" responses, as does sympathetic stimulation. A is out because insulin causes cell to take up glucose. It is not involved in "fight or flight" responses. B is out because acetylcholine is a neurotransmitter; it has few, if any, known hormonal actions. D is out because aldosterone is involved in sodium reabsorption by the kidney; it has no role in "fight or flight" responses. |
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When compared with the actions of the nervous system those of the endocrine system are:
A. quicker in responding to changes, and longer-lasting B. quicker in responding to changes and shorter-lasting C. slower in responding to changes, and long lasting D. slower in responding to cahnges, and shorter-lasting |
C
C is correct. The nervous and endocrine systems are in general, the two systems that respond to changes in the environment. In general, the endocrine system's responses are slower to occur but last longer. |
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Insulin shock occurs when a patient with diabetes self administers too much insulin. Typical symptoms are extreme nervousness, trembling, sweating, and ultimately loss of consciousness. The physiological effects of insulin shock most likely include:
A. a pronounced increase in gluconeogenesis by the liver B. a rise in blood fatty acid levels leading to atherosclerosis C. a dramatic rise in blood pressure D. dangerously low blood glucose levels |
D
D is correct. The only important thing to recognize from the question is that high insulin levels exist. Then go to the basics; insulin decreases blood glucose. |
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Vasopressin, a hormone involved in water balance, is produced in the:
A. hypothalamus B. posterior pituitary C. anterior pituitary D. kidney |
A
A is correct. This is an important distinction to be made. The hormones of the posterior pituitary are synthesized in the bodies of neurons in the hypothalamus, and transported down the axons of these nerves to the posterior pituitary. |
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Osteoprosis is an absolute decrease in bone tissue mass, especially trabecular bone. All of the following might be contributory factors to the disase EXCEPT:
A. increased sensitivity to endogenous parathyroid hormone B. defective intestinal calcium absorption C. menopause D. abnormally high blood levels of calcitonin |
D.
D is correct. Calcitonin builds bone mass. Menopause contributes to osteoporosis by reducing estrogen levels leading to diminished osteoblastic activity. You are not required to know this, and may have had difficulty in eliminating this answer. Instead, you should know this question by realizing that D was the exception. |
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All of the following hormones are produced by the anterior pituitary EXCEPT:
A. thyroxine B. growth hormone C. prolactin D. leutinizing hormone |
A
A is correct. Thyroixin (T4) is produced by the thyroid gland |
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Which of the following hormonal and physiologic effects of stress would NOT be expected in a marathoner in the last mile of a marathon?
A. Increased glucagon secretion B. Increased heart rate C. Decreased ACTH secretion D. Decreased blood flow to the small intestine |
C
C is correct. Glucagon increases blood sugar, a good thing if you are running a marathon. An increased heart rate and sympathetic blood shunting might similarly be expected ini isomone who had just run 25 miles. |
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Parathyroid hormone is an important hormone in the control of blood calcium ion levels. Parathyroid hormone directly impacts:
I. bone density II. renal calcium reabsorption III. blood calcium concentration A. I only B. I and II only C. I and III only D. I, II, and III |
D
D is correct. Parathyroid hormone stimulates osteoclast (bone resorbtion) activity. It also works in the kidney to slow calcium lost in urine. It controls blood calcium levels via these two mechanisms. |
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A drug that causes increased secretion of testosterone from the interstitial cells of a physically mature male would most likely:
A. cause the testes to descend prematurely B. dleay the onset of puberty C. cause enhanced secondary sex characteristics D. decrease core body temperature |
C
C is correct. A looks good (testosterone does stimulate the testes to descend) until you notice that we're dealing with a physically mature male. The testes normally descend during late fetal development. B is out because increased testosterone would casue puberty to occur early, and would not change the timing of puberty if it's already happened (we are, after all, dealing with a physically mature male). D is out because we don't know of any direct mechanism by which testosterone increases body temperature. |
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During the female menstrual cycle, increasing levels of estrogen cause:
A. a positive feedback response, stimulating LH secretion by the anterior pituitary B. a positive feedback response, stimulating FSH secretion by the anterior pituitary C. a negative feedback response, stimulating a sloughing-off of the uterine lining. D. a negative feedback response, stimulating decreased progesterone secretion by the anterior pituitary |
A
A is correct. Increased secretion of estrogen sets off the luteal surge, which involves increased secretion of LH and leads to ovulation |
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The function of the epididymus is to:
A. store sperm until they are released during ejaculation B. produce and secrete testosterone C. conduct the ovum from the ovary into the uterus D. secrete FSH and LH to begin the menstrual cycle. |
A
A is correct. The epididymus is where the sperm goes to mature and be stored until ejaculation. Testosterone is secreted by the seminiferous tubules. |
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Decreasing progesterone levels during the luteal phase of the menstrual cycle are associated with:
A. thickening of the endometrial lining in preperation for implantation of the zygote B. increased secretion of LH, leading to the luteal surge and ovulation C. degeneration of the corpus luteum in the ovary D. increased secretion of estrogen in the follicle, leading to the flow phase of the menstrual cycle |
C
C is correct. Decreased progesterone secretion results from the degeneration of the corpus luteum, which occurs because fertilization of the egg and implantation didn't happen. A is out because thickening of the endometrial lining occurs while estrogen and progesterone levels are high, not while progesterone secretion is decreasing. B is out because increased estrogen secretion causes the luteal surge, and because the luteal surge occurs earlier in the cycle. D is out because, while the flow phase does follow decreased progesterone secretion, it does not occur as a result of increased estrogen secretion. |
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The inner linings of the Fallopian tubes are covered with a layer of cilia. The purpose of this layer is to:
A. remove particulate matter that becomes trapped in the mucus layer covering the Fallopian tubes B. maintain a layer of warm air close to the inner lining, protecting the ovum from temperature changes occurring in the external environment C. kill incoming sperm, thus preventing fertilization D. facilitate movement of the ovum towards the uterus |
D
D is correct. The layer of cilia along the inner lining of the Fallopian tubes serves to help the egg cell move towards the uterus, where it will implant if it has been fertilized. (Fertilization usually happens in the Fallopian tubes) A describes what the ciliary lining in the respiratory tract does. B may sound good, but the Fallopian tubes are far enough away from the external environment that protection from its tempearutre fluctuation is not an issue. C would seem to gum up the whole "continuation of the species" plan. It's not a good answer. |
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Which of the following endocrine glands produce testosterone?
A. the anterior pituitary B. the pancreas C. the adrenal cortex D. the adrenal medulla |
C
C is correct. The adrenal cortex makes many other steroid based hormones, as well as testosterone |
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Which of the following does NOT describe cleavage in human embryos?
A. The solid ball of cells produced during cleavage is called a morula B. The size of the embryo remains constant throughout the cell divisions of cleavage C. Cell division occurs in one portion of the egg in meroblastic cleavage D. Daughter cells are genetically identical to parent cells |
C
C is correct. Mammalian eggs undergo holoblastic cleavage where division occurs throughout the whole egg. At first glance, this question appears to ask for somewhat obscure knowledge about meroblastic cleavage. However, you should be able to eliminate A, B, and D quite easily as being part of human embryonic cleavage, so it is necessary to know meroblastic or holoblastic cleavage. |
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The heart, bone, and skeletal msucle most likely arise from which of the following primary germ layers?
A. The ectoderm B. The endoderm C. The gastrula D. The mesoderm |
D
D is correct. Generally, the inner lining of the respiratory and digestive tracts, and associated organs, come from the endoderm. The skin, hair, nails, eyes and central nervous system come from ectoderm. Everything else comes from the mesoderm. The gastrula is not a germ layer. |
