Hormonal Regulation Of Fuel Metabolism
SGU BiochemistrySpring 2010Lecture 60: Dr. L. D.
Questions and Answers
- 1.
The _____ of nutrients or metabolites in the blood affects the rate at which they are used and stored in different tissues. p1
Explanation
The concentration of nutrients or metabolites in the blood refers to the amount of these substances present in the blood. This concentration plays a crucial role in determining the rate at which they are utilized and stored in various tissues of the body. Higher concentrations of nutrients or metabolites in the blood generally lead to increased utilization and storage in tissues, while lower concentrations may result in slower rates of utilization and storage. Therefore, the concentration of these substances in the blood directly influences their metabolic processes within the body.Rate this question:
- 2.
_______ are the body's chemical messengers. They transmit information from one set of cells to another.
Explanation
Hormones are chemical messengers that are produced by various glands in the body and are released into the bloodstream. They travel to specific target tissues and organs, where they convey important information about the physiological state of the body and the nutrient supply or demand. Hormones play a crucial role in regulating various bodily functions such as metabolism, growth and development, reproduction, and mood. They help to maintain homeostasis and ensure that the body's systems are working properly.Rate this question:
- 3.
The _______ system controls tissue metabolism, directly or through hormone release p1
Explanation
Comprising a variety of hormones, the endocrine system oversees every biological process in the body from conception through adulthood and into old age. It plays a crucial role in the development of the brain and nervous system, the functionality and growth of the reproductive system, and the metabolism along with blood sugar levels.Rate this question:
- 4.
Insulin and ______ are the two major hormones that regulate fuel storage and mobilization p1
Explanation
Insulin and glucagon are the two major hormones that regulate fuel storage and mobilization. Insulin promotes the uptake and storage of glucose in cells, lowering blood sugar levels. On the other hand, glucagon stimulates the breakdown of glycogen in the liver, releasing glucose into the bloodstream and increasing blood sugar levels. Together, insulin and glucagon work in a delicate balance to maintain stable blood sugar levels and ensure the body has a constant supply of energy.Rate this question:
- 5.
Insulin is the major ____ hormone of the body p1
- A.
Anabolic
- B.
Catabolic
Correct Answer
A. AnabolicExplanation
Insulin is considered the major anabolic hormone of the body because it promotes the storage and synthesis of energy-rich molecules such as glycogen, proteins, and lipids. It helps to lower blood glucose levels by facilitating the uptake of glucose into cells and promotes the conversion of glucose into glycogen for storage in the liver and muscles. Additionally, insulin stimulates protein synthesis and inhibits protein breakdown, promoting muscle growth and repair. Therefore, insulin plays a crucial role in building and maintaining body tissues and promoting overall growth and development.Rate this question:
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- 6.
The major action of glucagon is to mobilize fuel stores by stimulating glycogenolysis and _______ p1
Correct Answer
gluconeogenesisExplanation
Glucagon is a hormone released by the pancreas that plays a crucial role in maintaining blood sugar levels. One of its primary functions is to stimulate the breakdown of glycogen, a stored form of glucose, into glucose molecules through a process called glycogenolysis. Additionally, glucagon promotes the production of new glucose molecules from non-carbohydrate sources, such as amino acids and fatty acids, in the liver through a process known as gluconeogenesis. This helps to increase blood sugar levels and provide a steady supply of fuel for the body during times of fasting or low blood sugar.Rate this question:
- 7.
Like glucagon, epinephrine, norepinephrine, and _______ have counterrgulatory activity p1
Correct Answer
cortisolExplanation
Cortisol is suggested as the answer because it is known to have counterregulatory activity, similar to glucagon, epinephrine, and norepinephrine. These hormones are released in response to stress or low blood sugar levels, and they work to increase blood sugar levels by promoting the breakdown of glycogen and stimulating gluconeogenesis. Cortisol, a steroid hormone produced by the adrenal glands, also plays a role in increasing blood sugar levels during times of stress or fasting. Therefore, cortisol is a logical choice to complete the list of hormones with counterregulatory activity.Rate this question:
- 8.
_____ is a polypeptide hormone secreted by the B cells of the islets of Langerhans slide9
Correct Answer
insulinExplanation
Insulin is a polypeptide hormone that is secreted by the B cells of the islets of Langerhans. It plays a crucial role in regulating blood sugar levels by facilitating the uptake and utilization of glucose by cells. Insulin helps to lower blood sugar levels by promoting the storage of glucose in the liver and muscles as glycogen, and by inhibiting the release of glucose from the liver. It also stimulates the synthesis of proteins and the storage of fats. Overall, insulin is essential for maintaining normal blood sugar levels and for proper metabolism.Rate this question:
- 9.
_____ is the most important hormone coordinating the use of fuels by tissues s9
- A.
Glucagon
- B.
Cortisol
- C.
Epinephrine
- D.
Insulin
- E.
Norepinephrine
Correct Answer
D. InsulinExplanation
Insulin is the most important hormone coordinating the use of fuels by tissues because it plays a crucial role in regulating the metabolism of carbohydrates, fats, and proteins. Insulin helps to lower blood sugar levels by promoting the uptake and storage of glucose in cells, especially in muscle and adipose tissue. It also inhibits the breakdown of glycogen and stimulates the synthesis of glycogen in the liver. Additionally, insulin promotes the synthesis of proteins and the storage of fats. Overall, insulin helps to maintain stable blood sugar levels and ensures that tissues have a steady supply of fuel for energy production.Rate this question:
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- 10.
Insulin signals the fed state and thus stimulates the storage of fuels (glycogen and TAGs) and stimulates the synthesis of _____ s9
Correct Answer
proteins
proteinExplanation
Insulin is a hormone that is released by the pancreas in response to high levels of glucose in the blood. It signals the fed state and promotes the storage of fuels such as glycogen and TAGs (triacylglycerols). In addition to this, insulin also stimulates the synthesis of proteins. This is important for growth, repair, and maintenance of tissues in the body. Therefore, the correct answer is proteins or protein.Rate this question:
- 11.
Insulin consists of 51 amino acids arranged in two polypeptide chains linked by two _____ _____. s10
Correct Answer
disulfide bridges, disulfide bonds, disulphide bridges , disulfide, disulphideExplanation
Insulin is a hormone that helps regulate blood sugar levels. It is composed of 51 amino acids arranged in two polypeptide chains. These chains are linked together by two disulfide bridges or disulphide bridges. These bridges are formed when two cysteine amino acids come close together and their sulfur atoms bond, creating a strong covalent bond. These bridges are important for the stability and structure of insulin, allowing it to function properly in the body.Rate this question:
- 12.
______ is the most important stimulus for insulin secretion s13
Correct Answer
glucoseExplanation
Glucose is the most important stimulus for insulin secretion. Insulin is a hormone produced by the pancreas that helps regulate blood sugar levels. When glucose levels in the blood rise, the pancreas releases insulin to signal cells to take in and use glucose for energy. This helps lower blood sugar levels back to normal. Therefore, glucose acts as a trigger for the secretion of insulin, making it the most important stimulus for insulin release.Rate this question:
- 13.
Ingestion of protein causes a transient rise in plasma ___ ____ levels, which induces insulin secretion p2
Correct Answer
amino acidExplanation
When protein is ingested, it gets broken down into amino acids in the digestive system. These amino acids are then absorbed into the bloodstream and cause a temporary increase in plasma amino acid levels. This increase in plasma amino acid levels stimulates the release of insulin from the pancreas. Insulin helps regulate blood sugar levels by promoting the uptake of glucose by cells, thereby reducing blood sugar levels. Therefore, the ingestion of protein leads to a transient rise in plasma amino acid levels, which in turn triggers the secretion of insulin.Rate this question:
- 14.
A number of gastrointestinal hormones, called ______, stimulate insulin secretion after the ingestion of food, causing an anticipatory rise in insulin levels. This accounts for the fact that the same amount of glucose given orally induces a much greater secretion of insulin than given IV s13/14
Correct Answer
incretinsExplanation
Incretins are gastrointestinal hormones that stimulate insulin secretion after the ingestion of food. They cause an anticipatory rise in insulin levels, which explains why the same amount of glucose given orally induces a much greater secretion of insulin than when given intravenously.Rate this question:
- 15.
Epinephrine is secreted by the _____ ________ in response to stress, trauma, or extreme exercise s15
Correct Answer
adrenal medullaExplanation
Epinephrine, also known as adrenaline, is a hormone that is released by the adrenal medulla. The adrenal medulla is a part of the adrenal glands, which are located on top of the kidneys. When the body is exposed to stress, trauma, or extreme exercise, the adrenal medulla is stimulated to release epinephrine into the bloodstream. This hormone helps to prepare the body for a "fight or flight" response by increasing heart rate, constricting blood vessels, and increasing blood sugar levels.Rate this question:
- 16.
Hyperglycemia leads to an increased transport of glucose into the B cell via ______ p3
- A.
GLUT1
- B.
GLUT2
- C.
GLUT3
- D.
GLUT4
- E.
GLUT5
Correct Answer
B. GLUT2Explanation
Hyperglycemia leads to an increased transport of glucose into the B cell via GLUT2. GLUT2 is a glucose transporter protein that is primarily found in the liver, pancreas, and small intestine. It has a high capacity for glucose transport and is responsible for transporting glucose into the pancreatic beta cells, where it is used for insulin secretion. When blood glucose levels are high, GLUT2 helps to facilitate the uptake of glucose into the beta cells, leading to increased insulin secretion to lower blood glucose levels.Rate this question:
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- 17.
The entry of glucose into the glycolytic pathway results in a(n) ______ in ATP levels s16
- A.
Increase
- B.
Decrease
Correct Answer
A. IncreaseExplanation
When glucose enters the glycolytic pathway, it undergoes a series of reactions that ultimately lead to the production of ATP. This is because glucose is broken down and its energy is harnessed through the process of glycolysis. As a result, the entry of glucose into the glycolytic pathway leads to an increase in ATP levels.Rate this question:
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- 18.
Insulin _____ glucose entry in muscle and adipose tissue s18
- A.
Stimulates
- B.
Inhibits
Correct Answer
A. StimulatesExplanation
Insulin stimulates glucose entry in muscle and adipose tissue. Insulin is a hormone produced by the pancreas that helps regulate blood sugar levels. When insulin is released into the bloodstream, it binds to insulin receptors on the surface of muscle and adipose (fat) cells. This binding triggers a series of cellular events that result in the movement of glucose transporters to the cell membrane, allowing glucose to enter the cells. This process helps to lower blood sugar levels by promoting the uptake and storage of glucose in muscle and adipose tissue.Rate this question:
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- 19.
Insulin _____ glycogen synthesis in liver and muscle s18
- A.
Inhibits
- B.
Stimulates
Correct Answer
B. StimulatesExplanation
Insulin stimulates glycogen synthesis in the liver and muscle. Insulin is a hormone produced by the pancreas that helps regulate blood sugar levels. When insulin is released, it signals the liver and muscle cells to take in glucose from the bloodstream and convert it into glycogen. Glycogen is a storage form of glucose that can be used later when energy is needed. Therefore, insulin plays a crucial role in promoting glycogen synthesis by stimulating the uptake and conversion of glucose into glycogen in the liver and muscle cells.Rate this question:
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- 20.
Insulin _____ fatty acid synthesis and storage as TAG in adipose tissue s18
- A.
Stimulates
- B.
Inhibits
Correct Answer
A. StimulatesExplanation
Insulin stimulates fatty acid synthesis and storage as TAG in adipose tissue. Insulin is a hormone that regulates glucose metabolism and plays a crucial role in the storage of excess energy as fat. It promotes the conversion of glucose into fatty acids and their subsequent storage as triglycerides (TAG) in adipose tissue. This process is important for maintaining energy balance and storing energy for future use.Rate this question:
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- 21.
Insulin _____ glycolysis s18
- A.
Stimulates
- B.
Inhibits
Correct Answer
A. StimulatesExplanation
Insulin stimulates glycolysis. Insulin is a hormone produced by the pancreas that helps regulate blood sugar levels. One of its main functions is to promote the uptake of glucose into cells. Once inside the cells, glucose is broken down through a series of reactions, with glycolysis being the first step. Insulin enhances the activity of enzymes involved in glycolysis, leading to increased glucose metabolism and energy production. This ultimately helps lower blood sugar levels and maintain cellular energy balance.Rate this question:
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- 22.
Insulin ______ gluconeogenesis s18
- A.
Sitmulates
- B.
Inhibits
Correct Answer
B. InhibitsExplanation
Insulin inhibits gluconeogenesis. Gluconeogenesis is the process by which the liver produces glucose from non-carbohydrate sources, such as amino acids and glycerol. Insulin acts to lower blood glucose levels by promoting glucose uptake by cells and inhibiting glucose production in the liver. Therefore, when insulin is present, it inhibits gluconeogenesis, preventing the liver from producing more glucose and helping to maintain blood glucose levels within a normal range.Rate this question:
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- 23.
Insulin ______ amino acid uptake by muscle s18
- A.
Inhibits
- B.
Stimulates
Correct Answer
B. StimulatesExplanation
Insulin stimulates amino acid uptake by muscle. Insulin is a hormone that regulates blood sugar levels and plays a crucial role in promoting the uptake and utilization of glucose and amino acids by cells. In the case of muscle cells, insulin stimulates the transport of amino acids into the muscle, which is essential for protein synthesis and muscle growth. This stimulation of amino acid uptake by insulin helps to support muscle development and repair.Rate this question:
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- 24.
The insulin receptor is a member of the ____ kinase family of receptors p3
Correct Answer
tyrosineExplanation
The insulin receptor belongs to the tyrosine kinase family of receptors. Tyrosine kinases are enzymes that add a phosphate group to the amino acid tyrosine in proteins. The insulin receptor, when activated by insulin binding, phosphorylates tyrosine residues in target proteins, initiating a signaling cascade that regulates glucose uptake and metabolism. This makes tyrosine the correct answer for the missing word in the given question.Rate this question:
- 25.
Insulin ____ hormone-sensitive lipase in adipose tissue p4
- A.
Inhibits
- B.
Stimulates
Correct Answer
A. InhibitsExplanation
Insulin inhibits hormone-sensitive lipase in adipose tissue. Hormone-sensitive lipase is responsible for breaking down stored fat in adipose tissue. When insulin is present, it signals the body to store glucose as glycogen and inhibits the breakdown of stored fat. This is because insulin promotes glucose uptake and utilization, and the body prefers to use glucose as an energy source rather than stored fat. Therefore, the correct answer is "inhibits."Rate this question:
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- 26.
Insulin ____ lipoprotein lipase in adipose tissue p4
- A.
Increases levels
- B.
Decreases levels
Correct Answer
A. Increases levelsExplanation
Insulin increases levels of lipoprotein lipase in adipose tissue. Lipoprotein lipase is an enzyme that plays a crucial role in breaking down triglycerides, which are stored in adipose tissue as fat. By increasing the levels of lipoprotein lipase, insulin promotes the breakdown of triglycerides into fatty acids, allowing them to be taken up and used by the body for energy. This process is important for regulating blood glucose levels and maintaining overall energy balance.Rate this question:
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- 27.
A decrease in plasma ____ levels is the primary stimulus for glucagon release s20
Correct Answer
glucoseExplanation
A decrease in plasma glucose levels is the primary stimulus for glucagon release. Glucagon is a hormone that is released by the pancreas when blood sugar levels are low. It acts to increase blood sugar levels by stimulating the liver to release stored glucose into the bloodstream. Therefore, when plasma glucose levels decrease, the body responds by releasing glucagon to help raise blood sugar levels back to normal.Rate this question:
- 28.
The main target tissue of glucagon is the ________ s21
Correct Answer
liverExplanation
Glucagon primarily targets the liver. Glucagon is a hormone released by the pancreas that plays a crucial role in regulating blood sugar levels. It acts on the liver to stimulate the breakdown of glycogen into glucose, which is then released into the bloodstream. This process, known as glycogenolysis, helps increase blood sugar levels when they are low, ensuring a steady supply of energy for the body. Therefore, the liver is the main target tissue of glucagon.Rate this question:
- 29.
Glucagon binds to G-protein coupled receptors on the plasma membrane of the hepatocyte. GLucagon receptors are coupled to the activation of ___ ____ s21
Correct Answer
adenylyl cyclaseExplanation
Glucagon binds to G-protein coupled receptors on the plasma membrane of the hepatocyte. These glucagon receptors are coupled to the activation of adenylyl cyclase. Adenylyl cyclase is an enzyme that catalyzes the conversion of ATP to cyclic AMP (cAMP). This activation of adenylyl cyclase by glucagon leads to an increase in cAMP levels within the cell, which in turn activates protein kinase A (PKA) and initiates a signaling cascade that ultimately leads to the stimulation of glycogen breakdown and glucose production in the liver.Rate this question:
- 30.
Glucagon _____ glycogen degradation s23
- A.
Inhibits
- B.
Stimulates
Correct Answer
B. StimulatesExplanation
Glucagon stimulates glycogen degradation. Glucagon is a hormone released by the pancreas that helps regulate blood sugar levels. When blood sugar levels are low, glucagon is released and it acts on the liver to stimulate the breakdown of glycogen into glucose. This glucose is then released into the bloodstream to increase blood sugar levels and provide energy for the body. Therefore, the correct answer is "stimulates".Rate this question:
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- 31.
Glucagon _____glycolysis 23
- A.
Stimulates
- B.
Inhibits
Correct Answer
B. InhibitsExplanation
Glucagon inhibits glycolysis. Glycolysis is the process by which glucose is broken down into pyruvate to produce energy. Glucagon is a hormone that is released by the pancreas when blood glucose levels are low. It acts to increase blood glucose levels by promoting the breakdown of stored glycogen in the liver and inhibiting the production of glucose through glycolysis. Therefore, glucagon inhibits glycolysis to prevent further glucose utilization and promote the release of glucose into the bloodstream.Rate this question:
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- 32.
Glucagon _____ fatty acid oxidation s23
- A.
Stimulates
- B.
Inhibits
Correct Answer
A. StimulatesExplanation
Glucagon stimulates fatty acid oxidation. When glucagon is released by the pancreas, it signals the liver to break down glycogen into glucose and release it into the bloodstream. This process also activates enzymes that promote the breakdown of fats (fatty acids) stored in adipose tissue. As a result, fatty acids are released into the bloodstream and transported to the liver, where they undergo oxidation to produce energy. Therefore, glucagon plays a crucial role in stimulating the process of fatty acid oxidation.Rate this question:
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- 33.
Glucagon _____ gluconeogenesis s23
- A.
Stimulates
- B.
Inhibits
Correct Answer
A. StimulatesExplanation
Glucagon stimulates gluconeogenesis. Gluconeogenesis is the process by which new glucose molecules are formed in the liver from non-carbohydrate sources such as amino acids and glycerol. Glucagon is a hormone that is released by the pancreas in response to low blood glucose levels. It acts on the liver to increase the breakdown of glycogen and promote the production of glucose through gluconeogenesis. This helps to raise blood glucose levels and maintain a stable energy supply for the body.Rate this question:
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- 34.
Glucagon _____ fatty acid synthesis s23
- A.
Stimulates
- B.
Inhibits
Correct Answer
B. InhibitsExplanation
Glucagon inhibits fatty acid synthesis. Glucagon is a hormone that is released by the pancreas in response to low blood sugar levels. It acts to increase blood glucose levels by promoting the breakdown of stored glycogen in the liver and inhibiting the synthesis of new glucose. In addition, glucagon inhibits the synthesis of fatty acids by blocking the enzyme called acetyl-CoA carboxylase, which is necessary for fatty acid synthesis. This helps to conserve energy and prevent the storage of excess fat when blood sugar levels are low.Rate this question:
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- 35.
_____ is the precursor of all catecholamines p6
Correct Answer
tyrosineExplanation
Tyrosine is the precursor of all catecholamines. Catecholamines are a group of neurotransmitters and hormones that include dopamine, norepinephrine, and epinephrine. These chemicals are derived from tyrosine through a series of enzymatic reactions. Tyrosine is converted into L-DOPA, which is then further converted into dopamine, norepinephrine, and epinephrine. Therefore, tyrosine plays a crucial role in the synthesis of catecholamines in the body.Rate this question:
- 36.
Epinephrine and norepinephrine _____ glucose uptake by muscle
- A.
Stimulate
- B.
Inhibit
Correct Answer
B. InhibitExplanation
Epinephrine and norepinephrine inhibit glucose uptake by muscle. These hormones belong to the catecholamine family and are released during stress or exercise. When released, they bind to specific receptors on muscle cells, activating a signaling pathway that leads to the inhibition of glucose uptake. This mechanism ensures that glucose is conserved for other tissues, such as the brain, which rely heavily on glucose for energy. By inhibiting glucose uptake, epinephrine and norepinephrine redirect energy resources to support immediate physiological needs during stressful situations.Rate this question:
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- 37.
Epinephrine and norepinephrine _____ insulin release
- A.
Stimulate
- B.
Inhibit
Correct Answer
B. InhibitExplanation
Epinephrine and norepinephrine inhibit insulin release. These hormones are released during periods of stress or fight-or-flight response. They work by increasing blood glucose levels to provide energy for the body to respond to the stressful situation. Inhibiting insulin release prevents glucose uptake by cells and promotes the breakdown of glycogen in the liver, leading to increased blood glucose levels. This mechanism ensures that the body has enough energy to deal with the stressor, rather than storing it as glycogen or fat.Rate this question:
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- 38.
Epinephrine and norepinephrine _____ mobilization of glycogen and TAGs
- A.
Stimulate
- B.
Inhibit
Correct Answer
A. StimulateExplanation
Epinephrine and norepinephrine stimulate the mobilization of glycogen and TAGs. These hormones are released during times of stress or exercise and act on various tissues, including the liver and adipose tissue. They activate enzymes that break down glycogen into glucose, which can be used as an energy source. Additionally, they promote the breakdown of TAGs stored in adipose tissue into fatty acids, which can also be utilized for energy production. Overall, the action of epinephrine and norepinephrine stimulates the release of stored energy sources to meet the increased demands of the body.Rate this question:
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- 39.
Epinephrine and norepinephrine act on ____ receptors s33
Correct Answer
adrenergicExplanation
Epinephrine and norepinephrine act on adrenergic receptors. Adrenergic receptors are a type of receptor that are found in the sympathetic nervous system and are activated by the release of epinephrine and norepinephrine. These receptors play a crucial role in the body's response to stress and help regulate various physiological processes, such as heart rate, blood pressure, and metabolism. Therefore, the correct answer is adrenergic.Rate this question:
- 40.
Epinephrine is a potent activator of ___ adrenoceptors
- A.
Alpha
- B.
Beta
- C.
Alpha and beta
Correct Answer
C. AlpHa and betaExplanation
Epinephrine is a potent activator of both alpha and beta adrenoceptors. Adrenoceptors are receptors that respond to adrenaline (epinephrine) and noradrenaline (norepinephrine). Alpha adrenoceptors are found in smooth muscle tissues and when activated, cause vasoconstriction and increased blood pressure. Beta adrenoceptors are found in the heart and when activated, increase heart rate and contractility. Epinephrine acts on both types of adrenoceptors, leading to a wide range of physiological responses including increased heart rate, bronchodilation, and vasoconstriction.Rate this question:
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- 41.
Norepinephrine activates ___ receptors. s34
- A.
Beta1, alpha
- B.
Beta2, apha
- C.
Only alpha
- D.
Only beta1
- E.
Only beta2
Correct Answer
A. Beta1, alpHaExplanation
Norepinephrine activates both beta1 and alpha receptors. Beta1 receptors are found primarily in the heart and are responsible for increasing heart rate and contractility. Alpha receptors are found in blood vessels and cause vasoconstriction when activated by norepinephrine.Rate this question:
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- 42.
Alpha1 receptors activate _______ _ via Gq s35
Correct Answer
phospholipase c
PLCExplanation
Alpha1 receptors activate phospholipase c (PLC) via Gq s35. Phospholipase c is an enzyme that plays a crucial role in signal transduction pathways. When alpha1 receptors are activated, they stimulate the Gq protein, which in turn activates phospholipase c. This activation leads to the cleavage of phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol trisphosphate (IP3) and diacylglycerol (DAG). IP3 acts as a second messenger, causing the release of calcium from intracellular stores, while DAG activates protein kinase C (PKC), initiating various cellular responses. Therefore, alpha1 receptors activate phospholipase c, leading to important cellular signaling processes.Rate this question:
- 43.
PLC catalyzes hydrolysis of PIP2 leading to generation of DAG and IP3. ___ stimulates release of calcium from intracellular stores. s35
Correct Answer
ip3Explanation
IP3 is the molecule that stimulates the release of calcium from intracellular stores. PLC catalyzes the hydrolysis of PIP2, which results in the generation of DAG and IP3. While DAG remains in the membrane and activates protein kinase C, IP3 diffuses into the cytoplasm and binds to IP3 receptors on the endoplasmic reticulum, triggering the release of calcium ions into the cytoplasm. Therefore, IP3 is responsible for the release of calcium from intracellular stores.Rate this question:
- 44.
In the liver, increases in calcium levels activate ___ ____ and stimulate glycogenolysis s37
Correct Answer
phosphorylase kinaseExplanation
Increases in calcium levels in the liver activate phosphorylase kinase. Phosphorylase kinase is an enzyme that plays a crucial role in glycogenolysis, the breakdown of glycogen into glucose. When calcium levels rise, phosphorylase kinase is activated, leading to the activation of glycogen phosphorylase, which in turn breaks down glycogen into glucose. This process helps to increase blood glucose levels and provide energy during times of need.Rate this question:
- 45.
In smooth muscle, increases in calcium levels cause ____ as a result of activation of myosin light chain kinase (SmMLCK). s38
- A.
Contraction
- B.
Relaxation
Correct Answer
A. ContractionExplanation
Increases in calcium levels in smooth muscle cause contraction as a result of activation of myosin light chain kinase (SmMLCK). This is because calcium binds to calmodulin, which then activates SmMLCK. SmMLCK phosphorylates the myosin light chain, leading to cross-bridge formation between actin and myosin and subsequent contraction of the smooth muscle.Rate this question:
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- 46.
___ receptors are the major adrenergic receptors in the heart s40
- A.
B1
- B.
B2
- C.
B3
Correct Answer
A. B1Explanation
B1 receptors are the major adrenergic receptors in the heart. These receptors are predominantly found in the cardiac muscle and are responsible for mediating the effects of norepinephrine and epinephrine on the heart. Activation of B1 receptors leads to an increase in heart rate, contractility, and conduction velocity, thereby enhancing cardiac output. B2 receptors, on the other hand, are mainly found in the smooth muscle of the bronchioles and blood vessels, while B3 receptors are primarily located in adipose tissue. However, neither B2 nor B3 receptors have a major role in the cardiac function.Rate this question:
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- 47.
In liver and skeletal muscle, activation of B2 receptors leads to ____ of glycogen phosphorylase and ___ of glycogen synthase
- A.
Activation / activation
- B.
Activation / inactivation
- C.
Inactivation / inactivation
- D.
Inactivation / activation
Correct Answer
B. Activation / inactivationExplanation
Activation of B2 receptors in liver and skeletal muscle leads to the activation of glycogen phosphorylase, which promotes the breakdown of glycogen into glucose. At the same time, it also leads to the inactivation of glycogen synthase, which inhibits the synthesis of glycogen. This dual effect helps to increase the availability of glucose for energy production in these tissues.Rate this question:
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- 48.
In smooth muscle, activation of B2 receptors leads to ____
- A.
Contraction
- B.
Relaxation
Correct Answer
B. RelaxationExplanation
Activation of B2 receptors in smooth muscle leads to relaxation. B2 receptors are primarily found in bronchial and vascular smooth muscle. When these receptors are activated, they stimulate the production of cyclic adenosine monophosphate (cAMP), which ultimately leads to smooth muscle relaxation. This relaxation allows for bronchodilation and vasodilation, which are important in various physiological processes such as airway opening and increased blood flow.Rate this question:
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- 49.
__ receptors are found predominantly in adipose tissue. Activation of __ receptors causes activation of TAG lipase, with resultant release of free fatty acids.
- A.
B1
- B.
B2
- C.
B3
Correct Answer
C. B3Explanation
B3 receptors are found predominantly in adipose tissue. Activation of B3 receptors causes activation of TAG lipase, with resultant release of free fatty acids.Rate this question:
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- 50.
Glucocorticoids are secreted by the _____ _____ s47
Correct Answer
adrenal cortexExplanation
Glucocorticoids are a type of steroid hormones that are secreted by the adrenal cortex. The adrenal cortex is the outer layer of the adrenal glands, which are located on top of the kidneys. These hormones play a crucial role in regulating various physiological processes in the body, including metabolism, immune response, and stress response. Therefore, the adrenal cortex is responsible for producing and releasing glucocorticoids into the bloodstream.Rate this question:
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