Endocrine Flashcards
A/an ________ is a membrane receptor that interacts with a special protein called a G-protein
A G-protein coupled receptor is a membrane receptor that interacts with a special protein called a G-protein
A/an [… hormone] is a hormone that consists of amino acids
(and give the examples)
A/an peptide hormone is a hormone that consists of amino acids
They’re Water soluble
Examples:
Insulin
Glucagon
Leptin
ADH
Oxytocin
A/an [… hormone] is a steroid that acts as a hormone
(give examples)
A/an steroid hormone is a steroid that acts as a hormone
Derived from lipids and are lipid soluble
Examples:
Estrogen
Progesterone
Testosterone
alpha-islet cells of the pancreas release […]
alpha-islet cells of the pancreas release glucagon
Antidiuretic hormone (ADH) promotes [increased or decreased] water retention and [increased or decreased] plasma osmolarity
(mention 3 facts)
Antidiuretic hormone (ADH) promotes increased water retention and deceased plasma osmolarity
- Increases blood pressure
- Produced in the hypothalamus
- Released from the posterior pituitary
Beta-islet cells of the pancreas release […]
Beta-islet cells of the pancreas release insulin
cAMP signaling is turned off when [enzyme] breaks the ring of cAMP and turns it into AMP
cAMP signaling is turned off when phosphodiesterase breaks the ring of cAMP and turns it into AMP
It is no longer cyclic
Epinephrine is a/an […]
Epinephrine is a/an catecholamine
Also known as adrenaline
Produced by the adrenal medulla
Increases HR
Increases BP
Cortisol increases blood sugar by […]
Cortisol increases blood sugar by activating gluconeogenesis
delta-islet cells of the pancreas release […]
delta-islet cells of the pancreas release somatostatin
cAMP, Ca2+, and inositol phosphates are […]
cAMP, Ca2+, and inositol phosphates are common 2nd messengers
Give the “four F’s” that are regulated by the hypothalamus:
[…]
[…]
[…]
[…]
Fighting
Fleeing
Feeding
Fucking
Epinephrine, norepinephrine, and dopamine are examples of […]
Epinephrine, norepinephrine, and dopamine are examples of catecholamines
They are neurohormones important in the stress response
Released by the adrenal medulla
GnRH stimulates the anterior pituitary to release […] and […]
GnRH stimulates the anterior pituitary to release FSH and LH
Gonadotropin-Releasing Hormone
GnRH is produced by the […] and released by the anterior pituitary
GnRH is produced by the hypothalamus and released by the anterior pituitary
Gonadotropin-Releasing Hormone
GPCRs are integral membrane proteins that possess [#] membrane-spanning domains or transmembrane helices
GPCRs are integral membrane proteins that possess seven membrane-spanning domains or transmembrane helices
Give the hormones that are produced by the anterior pituitary gland:
[…]
Give the steps in the GPCR sequence:
[…]
Give the steps in the GPCR sequence:
1 - Ligand binds to GPCR
2 - GPCR undergoes conformational change
3 - Alpha subunit exchanges GDP for GTP
4 - Alpha subunit dissociates and regulates target proteins
5 - Target protein relays signal as 2nd messenger and triggers cascade response
6 - GTP is hydrolyzed to GDP, everything returns to its original place, ready to repeat the sequence
Hormones can be grouped into three main types:
[…]
[…]
[…]
Hormones can be grouped into three main types:
Peptide hormones
Amine hormones
Steroid hormones
GnRH is produced by the hypothalamus and released by the […]
GnRH is produced by the hypothalamus and released by the anterior pituitary
Gonadotropin-Releasing Hormone
In an adrenergic receptor sequence, adenylyl cyclase removes 2 phosphates from […] to produce […]
In an adrenergic receptor sequence, adenylyl cyclase removes 2 phosphates from ATP to produce cAMP
cAMP is a second messenger
In the GPCR sequence, cAMP is a second messenger and does what […]
In the GPCR sequence, cAMP is a second messenger and triggers a response inside the cell
In the term G-protein, the “G” refers to […]
In the term G-protein, the “G” refers to the fact that they bind GTP and GDP
GTP = guanosine triphosphate
GPD = guanosine diphosphate
https://www.khanacademy.org/science/ap-biology/cell-communication-and-cell-cycle/signal-transduction/v/g-protein-coupled-receptors
Insulin and glucagon are [… hormones]
Insulin and glucagon are peptide hormones
Norepinephrine is a […] and is considered a hormone that serves as a neurotransmitter
Norepinephrine is a catecholamine and is considered a hormone that serves as a neurotransmitter
Increases HR
Increases BP
The adrenal cortex releases […] and […]
The adrenal cortex releases cortisol and aldosterone
Sits along the perimeter of the adrenal gland (top of kidney)
The G-Protein is classified as a heterotrimeric protein because […]
The G-Protein is classified as a heterotrimeric protein because it is made up of 3 subunits: α, β, γ
The G-Protein is made up of
The pineal gland secretes [hormone]
The pineal gland secretes melatonin
Located in the epithalamus, tucked into a groove between the two thalamus halves
The parathyroid gland’s primary function is to maintain the body’s […] and […] levels so that the nervous and muscular systems can function properly
The parathyroid gland’s primary function is to maintain the body’s Ca2+ and K+ levels so that the nervous and muscular systems can function properly
It is a collection of four parathyroid glands located on the back of the thyroid
The pancreas secretes digestive enzymes into the […]
The pancreas secretes digestive enzymes into the duodenum
α-islet cells release glucagon
β-islet cells release insulin
The posterior pituitary stores the following two hormones which are secreted by the hypothalamus:
[…]
[…]
The posterior pituitary stores the following two hormones which are secreted by the hypothalamus:
Oxytocin
Antidiuretic hormone (ADH)
The [… hormones] are relatively small hormones derived from the amino acids tyrosine and tryptophan
The amine hormones are relatively small hormones derived from the amino acids tyrosine and tryptophan
Examples include:
Catecholamines
Thyroid hormones
The […] are endocrine glands located above the kidneys and they produce a variety of hormones
The adrenal glands are endocrine glands located above the kidneys and they produce a variety of hormones
The [brain structure] releases hormones that regulate stress, growth, reproduction, and lactation
The anterior pituitary releases hormones that regulate stress, growth, reproduction, and lactation
Anterior lobe of the pituitary gland
The […] is the principal site of the conversion of tyrosine into the catecholamines
The adrenal medulla is the principal site of the conversion of tyrosine into the catecholamines
The adrenal medulla is located at the center of the adrenal gland, surrounded by the adrenal cortex which sits on top of the kidneys
The [brain structure] releases oxytocin and antidiuretic hormone (ADH)
The posterior pituitary releases oxytocin and antidiuretic hormone (ADH)
It is the posterior lobe of the pituitary gland
The [brain structure] is in charge of homeostasis and the 4 F’s
The hypothalamus is in charge of homeostasis and the 4 F’s
Regulates the autonomic nervous system via the endocrine system
Hormone pathway: Hypothalamus → hypophyseal portal → anterior pituitary
Type [#] diabetes is a chronic condition in which the pancreas produces little or no insulin
Type 1 diabetes is a chronic condition in which the pancreas produces little or no insulin
Glucose is not able to enter cells
[Hormone] stimulates the production and release of cortisol
ACTH stimulates the production and release of cortisol
Adrenocorticotropic Hormone
Released from the anterior pituitary
The […] is in the neck, below the Adam’s Apple, and secretes T3 and T4 hormones that regulate metabolism
The thyroid gland is in the neck, below the Adam’s Apple, and secretes T3 and T4 hormones that regulate metabolism
T4 = Thyroxine
T3 = Triiodothyronine
Also helps regulate calcium homeostasis
Type [#] diabetes is a chronic condition in which insulin receptors become desensitized and are not responsive to insulin
Type [2] diabetes is a chronic condition in which insulin receptors become desensitized and are not responsive to insulin
Glucose is not able to enter cells
[… receptors] are a class of G protein-coupled receptors that are targeted by catecholamines like norepinephrine and epinephrine
Adrenergic receptors are a class of G protein-coupled receptors that are targeted by catecholamines like norepinephrine and epinephrine
[…] are a group of hormones that play a role in male traits and reproductive activity
Androgens are a group of hormones that play a role in male traits and reproductive activity
They are steroid hormones and are converted to testosterone and estrogen in the gonads
[Hormone] is released by the thyroid gland and builds bone
Calcitonin is released by the thyroid gland and builds bone
Increases Ca2+ in bone
Increases Ca2+ excretion from kidneys
Decreases Ca2+ in blood
Decreases Ca2+ absorption in gut
[… hormone] stimulates the anterior pituitary to release ACTH
Corticotropin-releasing hormone stimulates the anterior pituitary to release ACTH
CRH
Produced by hypothalamus
[…] is a stress hormone released in response to stress and low blood-glucose concentration
Cortisol is a stress hormone released in response to stress and low blood-glucose concentration
Released by the adrenal cortex
[… hormones] act directly on the target tissue or organ
Direct hormones act directly on the target tissue or organ
Example: Insulin
[…] are released from the anterior pituitary and decrease pain
Endorphins are released from the anterior pituitary and decrease pain
[Hormone] is the primary female sex hormone and leads to the development of secondary sexual characteristics
Estrogen is the primary female sex hormone and leads to the development of secondary sexual characteristics
Produced by the ovaries
Regulates the menstrual cycle and decreases milk production
“Estrogen establishes; progesterone protects the endometrium”
[Hormone] has the following effects:
In males, it triggers spermatogenesis and stimulates Sertoli cells
In females, it stimulates the development of ovarian follicles
FSH has the following effects:
In males, it triggers spermatogenesis and stimulates Sertoli cells
In females, it stimulates the development of ovarian follicles
Follicle-Stimulating Hormone
Released from the anterior pituitary
[…] is a membrane receptor that transfers a signal from outside the cell to the inside of the cell
G-Protein Coupled Receptor (GPCR) is a membrane receptor that transfers a signal from outside the cell to the inside of the cell
About 50% of all modern drugs target GPCRs
[Hormone] causes the liver to convert stored glycogen into glucose
Glucagon causes the liver to convert stored glycogen into glucose
Peptide hormone secreted by alpha-islet cells of pancreas
[…] are glands that produces gametes (sex cells) and sex hormones
Gonads are glands that produces gametes (sex cells) and sex hormones
Males: testicles
Females: ovaries
[…] are a class of corticosteroids and include the hormone […]
Glucocorticoids are a class of corticosteroids and include the hormone cortisol
Released by adrenal cortex
[… hormone] stimulates the anterior pituitary to release FSH and LH
Gonadotropin-releasing hormone stimulates the anterior pituitary to release FSH and LH
GnRH
Produced by the hypothalamus
[… hormone] stimulates the anterior pituitary to release of GH
Growth hormone-releasing hormone stimulates the anterior pituitary to release of GH
GHRH
Produced by hypothalamus
[Hormone] stimulates growth and cell reproduction
Growth hormone stimulates growth and cell reproduction
Also known as somatotropin
Released from the anterior pituitary
[Hormone] signals liver, muscle, and fat cells to take in glucose from the blood
Insulin signals liver, muscle, and fat cells to take in glucose from the blood
Peptide hormone secreted by beta-islet cells of pancreas
[Hormone] is a gonadotropin that induces ovulation
LH is a gonadotropin that induces ovulation
Luteinizing Hormone
Released from the anterior pituitary
[…] induces ovulation in females and, in males, it initiates the production of testosterone
Luteinizing Hormone (LH) induces ovulation in females and, in males, it initiates the production of testosterone
[Hormone] regulates sleep / wakefulness and controls the circadian rhythm
Melatonin regulates sleep / wakefulness and controls the circadian rhythm
Released by the pineal gland
[…] are a class of corticosteroids and include the hormone […]
Mineral corticoids are a class of corticosteroids and include the hormone aldosterone
Released by adrenal cortex
[…] stimulates uterine contractions and breast milk production among other functions
Oxytocin stimulates uterine contractions and breast milk production among other functions
Produced in the hypothalamus
Released from the posterior pituitary
[Hormone] stimulates bone breakdown
Parathyroid hormone stimulates bone breakdown
Decreases Ca2+ in bone
Decreases Ca2+ excretion from kidneys
Increases Ca2+ in blood
Increases Ca2+ absorption in gut
Activates vitamin D (Calcitriol
[…] maintains and protects the endometrium
Progesterone maintains and protects the endometrium
“Estrogen establishes and progesterone protects the endometrium”
Progesterone responds to LH
[Hormone] stimulates milk production
Prolactin stimulates milk production
Released from the anterior pituitary
[Hormone] inhibits GH and also leads to lower insulin and lower glucagon
(GHIH) inhibits GH and also leads to lower insulin and lower glucagon
Growth Hormone-Inhibiting Hormone
Peptide hormone secreted by delta-islet cells of pancreas
[Thyroid hormone] is a precursor to [thyroid hormone]
T4 is a precursor to T3
T4 = Thyroxine
T3 = Triiodothyronine
Regulates metabolism
Created from Iodine and Tyrosine
[Hormone] is the primary male sex hormone and is an anabolic steroid
Testosterone is the primary male sex hormone and is an anabolic steroid
Produced by the testes in men and ovaries in women with a small amount produced by the Adrenal Cortex
[… hormone] stimulates the anterior pituitary to release TSH
Thyrotropin-releasing hormone stimulates the anterior pituitary to release TSH
TRH
Produced by hypothalamus
[… hormones] are hormones that act on endocrine glands, usually inducing them to secrete other hormones
Tropic hormones are hormones that act on endocrine glands, usually inducing them to secrete other hormones
Examples: GnRH and LH
[Amino acid] is the precursor to catecholamines
Tyrosine is the precursor to catecholamines
Tyrosine is converted into catecholamines in the adrenal medulla
41.
During times of stress the importance of having adequate levels of glucose, for utilization as energy, is dependent on hormonal secretions from the pancreas.
Which choice below will BEST ready the body for stressful situations?
A. Increased levels of glucagon and insulin.
B. Increased levels of glucagon and decreased
levels of insulin.
C. Decreased levels of glucagon and decreased
levels of insulin.
D. Decreased levels of glucagon and increased
levels of insulin.
B is correct, increased levels of glucagon and decreased levels of insulin. It is important to remember that glucose is needed by the body as an energy source. Thus, in times of stress, when the body needs energy to deal with the stressor, glucose plasma levels must increase. Sympathetic stimulation of glucagon secretion will increase glycogen breakdown and increase glucose plasma levels. This will make glucose available for tissues to utilize as an energy source. The sympathetic system will inhibit insulin secretion. The correct choice is B.
42 Ketosis is developed from an increase in the conversion of free fatty acids to ketone bodies. These ketone bodies are an important source of energy in times of fasting. However, prolonged ketosis will lead to a plasma acidosis due to liberated hydrogen ions from ketone bodies. A patient with acidosis will develop shortness of breath, dehydration, hypervolemia, and hypotension. In severe cases the acidosis and dehydration will depress consciousness to the point of coma.
Which choice below will lead to the development of ketosis and acidosis?
A. Increased levels of glucagon and insulin.
B. Increased levels of glucagon and decreased
levels of insulin.
C. Decreased levels of glucagon.
D. None of the above.
B is correct, increased levels of glucagon and decreased levels of insulin. The major function of glucagon secretion is to increase the amount of products in the plasma that can be utilized for energy production. During fasting, blood glucose levels are low, stimulating glucagon secretion. Glucagon secretion will increase the release of free fatty acids, which can be converted to ketone bodies and utilized for energy. However, if insulin levels are low, as in diabetes, ketone utilization is low and ketone products increase in the plasma beyond normal levels leading to ketosis and acidosis. The correct choice is B.
- Symptoms reported by a patient include weakness, dizziness, confusion, and hunger. Furthermore, some tremors, palpitations, and nervousness are also reported. These last symptoms are characteristic of hypoglycemia. The development of these symptoms is due to:
A. abnormal increases in insulin secretion.
B. abnormal decreases in insulin secretion.
C. abnormally high levels of plasma glucose.
D. abnormally low levels of free fatty acids.
A is correct, abnormal increases in insulin secretion. Hypoglycemia, by its name, means “low blood glucose.” Thus, abnormal increases in insulin secretion will decrease levels of blood glucose. Decreases in insulin secretion and high levels of plasma glucose are signs of hyperglycemia. Low levels of free fatty acids may indicate increases in insulin secretion or decreases in glucagon secretion. The correct choice is A.
What pancreatic hormonal response is expected after
a heavy protein intake?
A. Increased levels of insulin and glucagon.
B. Increased levels of insulin and decreased levels
of glucagon.
C. Decreased levels of insulin and glucagon.
D. Decreased levels of insulin and increased
levels o f glucagon.
A is correct, increased levels of insulin and glucagon. Increases in plasma amino acid concentrations will stimulate insulin secretion to promote protein production in cells. Furthermore, glucagon secretion from the pancreas is also increased. Glucagon secretion is needed to prevent hypoglycemia after a heavy protein meal since amino acids also stimulate insulin secretion. The correct choice is A.
From the data reported on glucose utilization of tissue and responsiveness of tissue to insulin, it may be determined that the main function of insulin secretion is:
A. increasing glucose uptake in the brain.
B. increasing glucose release from the liver.
C. access and storage of glucose in cells of the
peripheral tissues.
D. increasing glucose loss in the kidney.
C is correct, access and storage of glucose in cells of the peripheral tissue. Insulin stimulates the storage of glucose and eases the entry of glucose into tissue. The tissue affected most readily appears to be muscle and connective tissue of the periphery. The brain does not need insulin for glucose uptake, as brain tissue is not affected by insulin. Insulin stimulates glucose uptake and storage by the liver. Insulin will decrease glucose loss in the kidney by decreasing plasma glucose levels and increasing uptake of glucose by the tubular cells of the kidney. The correct
choice is C.
Patients diagnosed as having diabetes mellitus are said to be in “a state of starvation in the midst of plenty.” This analogy refers to:
A. extracellular glucose excess.
B. extracellular glucose deficiency.
C. decreased effects of insulin on intestinal
mucosa uptake of glucose.
D. deficiency of fatty acids in neural tissue.
A is correct, extracellular glucose excess. The lack of insulin secretion will decrease the uptake of glucose by cells. Even with extracellular concentrations of glucose rising, cells cannot utilize the glucose because it cannot enter the cells. Therefore, tissues die of starvation, with high concentration of glucose located just outside the cell. The correct choice is A.
Calcium and phosphate absorption in the intestines is stimulated by an increase in:
I. l,25(OH)2D3 n . Calcitonin IE. PTH
A. I only
B. I and II only
C. Ill only
D. I and III only
D is correct, I and HI only. In the second paragraph it was mentioned that in order to synthesize the activated form of vitamin D3 (l,25-(OH)2-D3), the hydroxylase enzyme in the kidneys must be activated (stimulated) by PTH. Once the activated hormone is synthesized, calcium and phosphate can be absorbed across the mucosa membrane of the intestines. The phosphate ion follows the calcium ion across the membrane so electrical neutrality is maintained. We can eliminate choice C because PTH by itself has no direct effect on either calcium or phosphate absorption in the intestines. We can also eliminate choice B because calcitonin does not allow for intestinal absorption of calcium or phosphate either. Even though choice A is a correct answer, it is not the BEST answer. In order to get the activated form of vitamin D, PTH is needed. Therefore, an increase in both PTH and subsequently an increase in
l,25-(OH)2-D3 is needed for absorption in the intestine. The correct choice is D.
In order for the secretion of calcitonin to have a greater effect on the concentration of calcium ions in the plasma, which of the following statements must be true regarding osteoclast activity and plasma calcium levels?
A. Increased osteoclast activity coupled with a hypercalcemic plasma.
B. Decreased osteoclast activity coupled with a hypercalcemic plasma.
C. Increased osteoclast activity coupled with a hypocalcemic plasma.
D. Decreased osteoclast activity coupled with a hypocalcemic plasma
A is correct, increased osteoclast activity coupled with a hypercalcemic plasma. Be careful with what this question is asking you to answer. The bottom line of what is being asked is: “What does it take in order to secrete calcitonin?” Calcitonin acts to loser plasma calcium levels. In order to lower those levels they must first be high. What leads to high calcium levels? Increased osteoclast activity (i.e., bone resorption and the return of calcium and phosphate to the blood) and a hypercalcemic plasma (i.e., a plasma in which the level of calcium is above normal). These two conditions demand a decrease in the levels of plasma calcium. The secretion of calcitonin by the parafollicular cells of the thyroid gland reduces the concentration of calcium in the blood. Calcitonin does this by inhibiting osteoclast activity (i.e., inhibits bone resorption) and inhibiting calcium reabsorption at the level of the kidney. The correct choice is A.
- Familial hypophosphatemia is BEST treated by diet modification and supplying adequate amounts of:
A. calcium.
B. phosphate.
C. calcium and phosphate.
D. phosphate and l,25(OH)2D3.
D is correct, phosphate and l,25-(OH)2-D3. Familial hypophosphatemia refers to the fact that there is inadequate phosphate in the plasma. As mentioned, this is an X-linked recessive disease and stems from the fact that
reabsorption of phosphate at the level of the kidneys is impaired. The addition of calcium will not affect the levels of phosphate and so we can eliminate choice A. Addition of phosphate alone will not make that much of a difference because it will not have an adequate means by which to be absorbed. We can eliminate choice B. We cam also eliminate choice C for the same reasoning. The addition of l,25-(OH)2-D3 along with the phosphate insures adequate absorption by the intestines and (presumably) an increased reabsorption at the level of the kidney. The correct choice is D.
Hypoparathyroidism is BEST characterized by:
I. increased osteoblast activity.
II. increased osteoclast activity.
III. increased neural excitability.
IV. increased plasma calcium concentrations.
A. I only
B. Handm only
C. m only
D. I and IV only
C is correct, increased neural excitability. Let’s consider the list of possible answers. In order to do this we need to know the meaning of hypoparathyroidism. The parathyroid glands secrete PTH and PTH allows for calcium absorption from bone by stimulating the osteoclasts and transiently inhibiting osteoblasts. PTH stimulates calcium reabsorbtion at the kidneys and indirectly allows for calcium absorption at the intestine through the action of the active form of vitamin D. A hypoparathyroid gland is one that does not secrete sufficient amounts of PTH. As a result the levels of calcium in the body decrease below normal values. Not only is osteoclast activity decreased, but because calcium levels are low, osteoblast activity is decreased as well. With this information we can eliminate choices A, B, and D. We are left with choice C as the correct answer. Why would hypoparathyroidism lead to increased neural activity? A decrease in calcium in the extracellular fluid allows more sodium to flow through the membranes of nerve cells. Some nerves, like those in the peripheral nervous system, begin to spontaneously discharge. This will eventually give rise to tetany and if not correct immediately can lead to death. The correct choice is C.
Osteoporosis is a disorder of bone characterized by a decrease in bone quantity, most common in women following menopause and in elderly men and women. Which of the following conditions would lead to the GREATEST decrease in bone quantity?
A. Decreased osteoblast activity, decreased osteoclast activity.
B. Increased osteoblast activity, decreased osteoclast activity.
C. Decreased osteoblast activity, increased osteoclast activity.
D. Increased osteoblast activity, increased osteoclast activity.
C is correct, decreased osteoblast activity, increased osteoclast activity. When bone synthesis is low (decreased osteoblast activity) and bone breakdown is high (increased osteoclast activity), the amount of bone decrease is the greatest. The correct choice is C.
What is the most abundant mineral in the human body?
A. B12
B. W a t e r
C. Calcium
D. Zinc
C is correct, calcium. The question asks for a mineral. Eliminate choice B, water, because water is a compound, not a single atom. B \2 is a vitamin, not a mineral, so choice A is incorrect. Since calcium was mentioned in the passage, consider it. Calcium is the major mineral making up bones. Our body contains about 1 kg of calcium. Although zinc
is part of many enzymes, our body contains only a lew grams of zinc. The correct choice is C.
Which of the following procedures is used on cells to isolate the entire insulin receptor for experimental studies?
A. Acidic wash.
B. Oxidizing wash.
C. Detergent wash.
D. Reducing wash.
C is correct, detergent wash. The passage informs us that the insulin receptor is an integral transmembrane protein. The receptor is thus embedded in the lipid bilayer and actually spans the entire layer from the extracellular to the intracellular face. These proteins arc tightly bound to the lipid bilayer by hydrophobic forces and harsh conditions are needed to remove them. In particular, detergents must be used. The reason is that these molecules are amphipathic, containing both a polar and non-polar region. The non-polar region binds to the hydrophobic regions of the membrane proteins, disrupting the lipid bilayer. The polar region creates a water soluble micelle with the membrane protein (hydrophobic portion) in the middle. The receptor is thus isolated and ready to study. The correct choice is C.
Through genetic manipulations, the insulin binding region of the insulin receptor (IR) was fused with the kinase region of the epidermal growth factor (EGF) receptor (also a ligand activated kinase). The resulting hybrid receptor was transfected into a cell and the addition of insulin resulted in a functional EGF kinase. From this experiment, it can be concluded that IR and EGF have similar:
A. ligand binding regions.
B. signal transduction mechanisms.
C. secondary messenger cascades.
D. effects on carbohydrate, fat, and protein
metabolism
B is correct, transduction mechanisms. We know from the question that we have a hybrid receptor which is made up of a insulin binding region and a EGF tyrosine kinase segment. From the passage, we know that the insulin receptor is believed to be a insulin activated tyrosine kinase. Recall that the binding of insulin leads to tyrosine kinase activity. The mechanism which brings about this activity is termed the signal transduction pathway. With our hybrid receptor, the binding of insulin leads to kinase activity in the EGF segment. This information indicates a similar signal transduction mechanism. The correct choice is B.
C is correct. The question tells us that the binding of glucagon will result in the production of the secondary messenger cAMP. The values of cAMP should thus rise with time. Using this piece of information, we can eliminate choices A and B. The question then becomes one of knowing the sequence of events. To answer this, one has to use previous knowledge and/or a little common sense. The secondary messengers produced lead to changes in the cell. Recall that to truly bring about change for the cell, there must be some change in proteins, as proteins are the key to function. One very common way to regulate proteins is through their phosphorylation and their dephosphorylation. It is the secondary messenger that promotes the phosphorylation of certain peptides, converting these proteins into their active forms. The active forms of the proteins bring about the change. From this information, the correct sequence of graphs can be seen. The correct choice is C.
In a type I, insulin dependent diabetes, the individual afflicted with the disease most likely has:
A. a mutated insulin binding site.
B. a mutated membrane anchoring site.
C. a normal insulin receptor.
D. an inactive phospholipase C.
C is correct, a normal insulin receptor. The question refers to a type I, insulin dependent diabetes. These individuals do not produce insulin. That is why they are dependent. This should clue us into the fact that their receptors more than likely have nothing wrong with them. The problem is that these individuals have no beta cells in the pancreas which release insulin. These individuals take insulin and their body responds appropriately. From this information, we can conclude that the receptors are more than likely normal. The correct choice is C.
Which of the following is consistentwith the actions of GIP?
A. Inhibition of hexokinase.
B. Inhibition of phosphofructokinase.
C. Stimulation of glycogen breakdown.
D. Stimulation of pyruvate dehydrogenase.
D is correct, stimulation of pyruvate dehydrogenase. We know from the passage that GIP mimics certain insulin responses. Therefore, we should look for an insulin response. Choice D indicates a stimulation of pyruvate dehydrogenase, the enzyme converting pyruvate into acetyl CoA. This would indicate an acceleration of glycolysis and the Krebs cycle. This is certainly one of the effects of insulin, as the hormone promotes the use of glucose as a source of fuel. The correct choice is D.
In cell #1, the addition of bivalent anti-insulin receptor antibodies induces a response without the addition of insulin. In cell #2, addition of a fragment anti-receptor antibody (monovalent) induces no response without insulin. To cell #2, antibodies against the monovalent anti-receptor antibodies are added. This will result in:
A. no response.
B. decreased glucose uptake .
C. increased CO2 production.
D. increased insulin binding.
C is correct, increased CO2 production. The question tells us that the addition of bivalent anti-insulin receptor antibodies induces a response without insulin. What will antibodies cause? The key word here is bivalent. The bivalent structure will induce cross-linking, leading to a clustering of insulin receptors. This conclusion is bolstered by the next sentence of the question which states that monovalent antibodies, which cannot produce cross-linking, do not induce a response in the absence of insulin. However, if we add antibodies against these monovalent antibodies/fragments, we should be able to induce cross-linking and thus clustering. Therefore, we should be able to induce an insulin-like response, which involves the promotion of glucose as a fuel. When glucose is oxidized, the carbons are released as carbon dioxide. The correct choice is C.
To disrupt the dimer in order to study its components, a researcher will most likely use:
A. oxidizing conditions.
B. reducing conditions.
C. high speed centrifugation.
D. high pH.
- B is correct, reducing conditions. This question is answered from our understanding of the conditions which are necessary to form or break disulfide bonds. When two cysteine residues are oxidized, the bond is formed and they form cystine. In order to break the bond, cystine must be placed in reducing conditions. From the passage, we know that the dimer insulin receptor is held with disulfide bonds. To isolate a component of the receptor for study, reducing conditions would be used to break these disulfide connections. The correct choice is B.
Cis 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. Answer choice A is out because the levels of renin in the blood would decrease, not increase; aldosterone release would increase blood pressure, and renin is released in response to low blood pressure. Oxytocin plays no role in blood pressure (vasopressin does) and would not be affected by this tumor. Choices C and D are both possibilities, but the adrenal cortex would definitely respond to negative feedback, while the tumor is a wild card. At this point, choice Cis the best answer. In fact, this is a good choice because normally, hormone-secreting tumors will not respond to negative feedback. Because the behavior of the tumor in unpredictable, choice 0 can be ruled out.
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. However, protein hormones do not. Steroids are derived from cholesterol, not protein precursors. Steroids, unlike protein hormones, do not act through a second messenger system
C is correct. Acetylcholine acts through a second messenger system, and is not a second messenger itself. The other choices, cAMP, cGMP, and calmodulin are all examples of second messengers.
- B is correct. Exocrine function refers to enzyme delivery through a duct. Answer choices C and 0 refer to hormones, which are always part of the endocrine function of a gland, so they can be eliminated. Releasing digestive enzymes straight into the blood would be a very bad idea. The same enzymes that help digest food would have no problem digesting the cells of the body.
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 at the transcription level in the nucleus, and are synthesized by the smooth endoplasmic reticulum.
What are the hormones released by the antuitray pituatiray
HALFPIT
- B is correct. Steroids act at the level of transcription by regulating the amount of mRNA transcribed. Because steroids diffuse into the cell and head for the nucleus, choice C can be eliminated -translation happens in the cytoplasm, not the nucleus. Although some steroid hormones have an effect on cellular growth, they don’t all control replication. In a cell, reactions are typically regulated by controlling relative concentrations of the enzyme and/or inhibitors (i.e. through regulation of transcription or translation).
- B is correct. This is another negative feedback question. T3 and T4 (thyroxine) production is controlled by a negative feedback mechanism involving TSH (thyroid stimulating hormone) from the anterior pituitary. If there is an exogenous source of thyroxine the body will sense the higher level and react by decreasing levels of TSH. If there is enough thyroxine around the anterior pituatary doesn’t need to produce TSH to tell the thyroid to produce more thyroxine. Parathyroid hormone production is not be affected by thyroxine levels.
- C is correct. Epinephrine release leads to “fight or flight” responses, as does sympathetic stimulation. Choice A is out because insulin causes cells to take up glucose. In fact, in the “flight or fight” response, it is advantageous for blood glucose levels to be higher and insulin secretion is suppressed. Choice B is out because acetylcholine is a neurotransmitter; it has few, if any, known hormonal actions. Choice D is out because aldosterone is involved in sodium reabsorption by the kidney; it has no role in “fight or flight” responses.
- D is correct. Calcitonin builds bone mass -it “tones the bone”. If there were excess levels of calcitonin this would increase bone tissue mass. Parathyroid hormone increases blood calcium levels in part by breaking down bone. Bring more sensitive to parathyroid hormone would certainly lead to a decrease in bone tissue mass. Defective intestinal calcium absorption would lead to low blood calcium levels and activation of parathyroid hormone in an attempt to restore blood calcium. Parathyroid hormone would break down bone to release the calcium into the blood. Menopause contributes to osteoporosis by reducing estrogen levels leading to diminished osteoblastic activity. Choice D has the opposite effect of any of the other choices, so it can also be picked in this way. The answer that is different from the rest will often be correct.
- 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. Telling the liver to make more glucose through gluconeogenesis will raise the blood glucose and is the job of glucagon. Although glucagon will definitely be released in response to the dangerously low blood glucose levels, it is not the direct result of high insulin.
- Cis correct. The nervous and endocrine systems are the two systems that respond to changes in the environment. In general, the endoorine system’s responses are slower to occur but last longer. Think about the difference in your reaction when you stub your toe- a nervous system response- and when you get stressed- and endocrine response.
- A is correct. Thyroxine (T4) is produced by the thyroid gland. The anterior pituitary hormones are FLAT PG (FSH, LH, ACTH, TSH, Prolactin, GH). Choice A would result from mixing up thyroixine, T41 with thyroid ttimulating hormone, or TSH.
- 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. Remember the hormones produced in the anterior pituitary are FLAT PG. The hormones produced in the hypothalamus are regulating hormones used to control the release of other hormones from the pituitary. The kidney is the target organ of vasopressin, not where it is produced.
Dis correct. Parathyroid hormone is all about raising blood calcium levels. It stimulates osteoclast (bone resorption) activity, decreasing bone density. It also works in the kidney to slow calcium lost in urine. It controls blood calcium levels via these two mechanisms. Because parathyroid hormone has to do with blood calcium levels choices A and B can be eliminated because they do not contain option III. Then, option I is in both remaining answers, so it does not need to be carefully considered. Afterwards, determine ifparathyroid hormone impacts renal calcium reabsorption, which it does.
A is correct. Increased secretion of estrogen sets off the luteal surge, which involves increased secretion of LH and leads to ovulation. Choice B is close, but estrogen stimulates a surge in LH, not FSH. Choice C describes what takes place when there are decreasing levels of estrogen. Progesterone is not secreted by the anterior pituitary: it is secreted by the placenta or the corpus luteum.
Cis correct. Answer choice A looks good (testosterone does stimulate the testes to descend) until the question states that the person is a physically mature male. The testes normally descend during late fetal development. Choice B is out because increased testosterone would cause puberty to occur early, and would not change the timing of puberty if it’s already happened (dealing with a physically mature male). Choice Dis out because it is unknown whether any direct mechanism by which testosterone increases body temperature exists. More testosterone does enhance secondary sex characteristics even in a physically mature male. Think about athletes using steroids (often exogenous testosterone) to have bigger muscles.
Cis correct. Glucagon increases blood sugar, a good thing while running a marathon. An increased heart rate would be expected in someone who had just run 25 miles. Blood flow to the small intestine would be rerouted to where it was need- the heart, lungs, and leg muscles. Remember, rest and digest, the body doestn’t want to waste blood flow for digestion while finishing the last mile of a marathon.
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. Choice A is out because thickening of the endometrial lining occurs while estrogen and progesterone levels are high, not while progesterone secretion is decreasing. Choice hoice B can be eliminated because increased estrogen secretion causes the luteal surge, and because the luteal surge occurs earlier in the cycle. Choice Dis out because while the flow phase does follow decreased progesterone secretion, it does not occur as a result of increased estrogen secretion.
Dis 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.) Choice A describes what the ciliary lining in the respiratory tract does. Choice B may sound good, but the Fallopian tubes are far enough away from the external environment that protection from its temperature fluctuations is not an issue. Choice C would seem to gum up the whole “continuation of the species” plan. The cilia would most likely try to improve the odds of fertilization rather than decrease it.
Cis correct. The adrenal cortex makes many other steroid based hormones, as well as testosterone. Again, the anterior pituitary hormones are FLAT PG. LH does stimulate the production of testosterone, but testosterone is not produced in the anterior pituitary. The pancreas produces insulin and glucagon. The adrenal medulla produces epinephrine and norepinephrine.
A is correct. The epididymis is where the sperm goes to mature and be stored until ejaculation. Leydig cells, next to the seminiferous tubules, secrete testosterone. Choice C is the job of the Fallopian tubes in a female . FSH and LH are secreted by the anterior pituitary.
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.
C is correct. Mammalian eggs undergo holoblastic cleavage where division occurs throughout the whole egg. At a first glance, this question appears to ask for somewhat obscure knowledge about meroblastic cleavage. However, choices A, B, and D can be eliminated because they are part of human embryonic cleavage, so it is unnecessary to know meroblastic or holoblastic cleavage.
Ednocrine glands diagram
Tropic hormones of anterior pituatary
Direct hormones of anterior pituatary
