1
Q
- What happens in the absence of an insulin signal?
- A) Glucose enters cells.
- B) Fats are mobilized.
- C) Ketone bodies accumulate.
- D) Acetyl-CoA is produced.
A
- B) Fats are mobilized.
2
Q
- Why can’t FFA (free fatty acids) make glucose?
- A) Due to loss of oxaloacetate.
- B) Insulin deficiency.
- C) High blood glucose levels.
- D) FFA cannot enter the Krebs cycle.
A
- A) Due to loss of oxaloacetate.
3
Q
- What is the consequence of ketone body accumulation in the blood?
- A) Hyperglycemia.
- B) Hypoglycemia.
- C) Ketoacidosis.
- D) Increased insulin sensitivity.
A
- C) Ketoacidosis.
its carboxylic acid bb
4
Q
- What is polyuria in the context of diabetes?
- A) Excessive hunger
- B) Increased thirst
- C) Frequent urination
- D) Elevated blood glucose levels
A
- C) Frequent urination
- with excess of glucose
5
Q
- Why does polyuria occur in diabetes?
- A) Inhibition of water resorption by the kidneys
- B) Increased blood volume
- C) Enhanced glucose utilization
- D) Activation of hypothalamic thirst centers
A
- A) Inhibition of water resorption by the kidneys
6
Q
- What is the consequence of polydipsia in diabetes?
- A) Dehydration
- B) Excessive hunger
- C) Frequent urination
- D) Electrolyte imbalance
A
- A) Dehydration
activated by hypothalamic thirst centers
7
Q
- What does polyphagia refer to in diabetic individuals?
- A) Excessive thirst
- B) Starvation due to inability to use ingested carbs
- C) Frequent urination
- D) Elevated blood glucose levels
A
- B) Starvation due to inability to use ingested carbs
Excessive Hunger
8
Q
- What characterizes Type 1 Diabetes?
- A) Loss of α cells
- B) Insulin resistance
- C) Destruction of β cells
- D) Excessive insulin production
A
- C) Destruction of β cells
9
Q
- What is the primary cause of Type 1 Diabetes?
- A) Genetic mutations
- B) Autoimmune reaction
- C) Viral infection
- D) Overconsumption of carbohydrates
A
- B) Autoimmune reaction
10
Q
- Why must individuals with Type 1 Diabetes take exogenous insulin?
- A) To prevent ketone body accumulation
- B) To enhance glucose utilization
- C) Due to loss of β cells and no endogenous insulin
production - D) To regulate blood pressure
A
- C) Due to loss of β cells and no endogenous insulin
production
11
Q
- What are the long-term complications associated with Type 1 Diabetes?
- A) Increased insulin sensitivity
- B) Atherosclerosis
- C) Enhanced bladder function
- D) Improved sensation in extremities
A
- B) Atherosclerosis
12
Q
- What is the estimated prevalence of Type 1 Diabetes in America?
- A) Approximately 1 million cases
- B) Over 10 million cases
- C) Less common than Type 2 Diabetes
- D) Prevalence varies by age group
A
A) Approximately 1 million cases
13
Q
- Which cells are specifically affected in Type 1 Diabetes?
- A) α cells
- B) δ cells
- C) β cells
- D) γ cells
A
- C) β cells
14
Q
- What is the potential cause of Type 1 Diabetes related to autoimmune reactions?
- A) Destruction of liver cells
- B) Loss of pancreatic duct cells
- C) Destruction of β cells
- D) Dysfunction of adrenal glands
A
- C) Destruction of β cells
15
Q
- What are the long-term complications associated with uncontrolled Type 1 Diabetes?
- A) Enhanced insulin sensitivity
- B) Increased energy levels
- C) Atherosclerosis and gangrene
- D) Improved bladder function
A
- C) Atherosclerosis and gangrene
16
Q
- What characterizes Type 2 Diabetes?
- A) Excessive insulin secretion
- B) Loss of β cells
- C) Reduced insulin sensitivity
- D) Autoimmune destruction of pancreatic tissue
A
- C) Reduced insulin sensitivity
17
Q
- What is the primary risk factor associated with Type 2 Diabetes?
- A) Age
- B) Sedentary lifestyle
- C) Genetic mutations
- D) Insulin resistance
A
- D) Insulin resistance
STRONG GENETIC COMPONENT
18
Q
- Why is ketoacidosis less common in Type 2 Diabetes compared to Type 1?
- A) Type 2 diabetics have better glucose control
- B) Type 2 diabetics produce more insulin
- C) Type 2 diabetics have fewer ketone bodies
- D) Type 2 diabetics are less prone to metabolic disturbances
A
- C) Type 2 diabetics have fewer ketone bodies
19
Q
- Which complications are Type 2 diabetics at risk for?
- A) Ketoacidosis
- B) Heart disease
- C) Enhanced circulation
- D) Improved insulin sensitivity
A
- B) Heart disease
20
Q
- What is the primary role of the liver in carbohydrate metabolism?
- A) Synthesizing monosaccharides
- B) Converting glucose to glycogen
- C) Facilitating gluconeogenesis
- D) Generating ketone bodies
A
- B) Converting glucose to glycogen
- C) Facilitating gluconeogenesis
21
Q
- What process allows the liver to release glucose into the bloodstream when needed?
- A) Glycogenolysis
- B) Gluconeogenesis
- C) Lipogenesis
- D) Glycolysis
A
- A) Glycogenolysis
22
Q
- Which metabolic function involves the liver generating ketone bodies?
- A) Carbohydrate metabolism
- B) Fat metabolism
- C) Protein synthesis
- D) Cholesterol regulation
A
- B) Fat metabolism
23
Q
- What is the primary purpose of lipoproteins produced by the liver?
- A) Transporting glucose
- B) Facilitating bile production
- C) Transporting triglycerides
- D) Regulating cholesterol levels
A
- C) Transporting triglycerides
24
Q
Certainly! Here are some questions related to the hepatic functions associated with metabolism based on the provided information:
- What is the principal role of the liver in protein metabolism?
- A) Synthesizing amino acids
- B) Generating plasma proteins
- C) Deaminating amino acids
- D) Producing essential amino acids
- What is the primary function of ferritin in the liver?
- A) To store glucose
- B) To transport iron
- C) To metabolize lipids
- D) To synthesize bile salts
A
- C) Deaminating amino acids
principal site of
25
2. **Why is the formation of urea important in protein metabolism?**
- A) It aids in amino acid synthesis.
- B) It removes excess ammonia.
- C) It enhances protein digestion.
- D) It regulates plasma cholesterol levels.
- B) It removes excess ammonia.
26
3. **Which vitamins are stored in significant amounts by the liver?**
- A) Vitamin C and E
- B) Vitamin A and D
- C) Vitamin B6 and B12
- D) Vitamin K and Folate
- B) Vitamin A and D
also b12 but not b6
27
4. **What is the primary function of ferritin in the liver?**
- A) To store glucose
- B) To transport iron
- C) To metabolize lipids
- D) To synthesize bile salts
- B) To transport iron
ferritin stores iron
28
What is the principal function of the liver in protein metabolism, particularly concerning amino acid deamination?
a) Synthesizing amino acids
b) Storing excess amino acids
c) Facilitating amino acid breakdown
d) Transporting amino acids to cells
c) Facilitating amino acid breakdown
(The liver's principal function in protein metabolism is to facilitate the breakdown of amino acids, particularly through processes like deamination.)
29
How does the liver contribute to the removal of ammonia from the body, and what role does urea play in this process?
a) Liver converts urea into ammonia for excretion
b) Liver synthesizes ammonia from urea for utilization
c) Liver forms urea from ammonia for excretion
d) Liver stores ammonia for future use
c) Liver forms urea from ammonia for excretion
(The liver converts toxic ammonia into urea, a less harmful compound, which is then excreted by the kidneys.)
30
Can you explain the liver's role in generating plasma proteins and the significance of this function?
a) Liver breaks down plasma proteins for energy
b) Liver stores plasma proteins for later use
c) Liver synthesizes most plasma proteins
d) Liver transports plasma proteins to tissues
c) Liver synthesizes most plasma proteins
(The liver is responsible for synthesizing the majority of plasma proteins, which are crucial for various physiological functions.)
31
What are non-essential amino acids, and how does the liver contribute to their synthesis through transamination?
a) Amino acids that are not important for health; liver breaks them down
b) Amino acids that must be obtained from the diet; liver stores them
c) Amino acids that can be synthesized by the body; liver facilitates their production
d) Amino acids that cannot be synthesized by the body; liver converts them into essential amino acids
c) Amino acids that can be synthesized by the body; liver facilitates their production
(Non-essential amino acids can be synthesized by the body, and the liver plays a key role in their production through processes like transamination.)
32
How does the liver store various vitamins and minerals such as Vitamin A, Vitamin D, Vitamin B12, and iron, and why is this storage important?
a) Liver excretes excess vitamins and minerals
b) Liver converts vitamins and minerals into energy
c) Liver stores vitamins and minerals for future use; important for metabolic functions
d) Liver releases vitamins and minerals into the bloodstream immediately upon ingestion
c) Liver stores vitamins and minerals for future use; important for metabolic functions
(The liver stores vitamins A, D, B12, and iron for future use, which is important for maintaining metabolic processes.)
33
Describe the liver's role in biotransformation, particularly inactivating compounds like ethanol and drugs. How does this process work?
a) Liver enhances the effects of ethanol and drugs
b) Liver breaks down ethanol and drugs into harmless compounds
c) Liver stores ethanol and drugs for later use
d) Liver transports ethanol and drugs to target tissues
b) Liver breaks down ethanol and drugs into harmless compounds
(The liver biotransforms various substances, including ethanol and drugs, into forms that are less toxic and can be easily excreted from the body.)
34
What is the significance of the liver's ability to activate certain drugs, and how does it accomplish this?
a) Liver reduces the effectiveness of drugs
b) Liver converts inactive drugs into active forms for therapeutic purposes
c) Liver stores inactive drugs for later use
d) Liver excretes active drugs from the body
b) Liver converts inactive drugs into active forms for therapeutic purposes
(The liver can activate certain drugs by converting them into active forms, enhancing their therapeutic effects.)
35
How does the liver process bilirubin from heme and what is the role of bile pigment in this process?
a) Liver converts bilirubin into heme for storage
b) Liver secretes bilirubin into bile for excretion
c) Liver breaks down bile pigment into bilirubin for utilization
d) Liver stores bilirubin for future metabolic needs
b) Liver secretes bilirubin into bile for excretion
(The liver processes bilirubin from heme and secretes it into bile for excretion from the body.)
36
Explain how the liver catabolizes hormones for excretion and why this is important for overall metabolic function.
a) Liver stores hormones for later use
b) Liver breaks down hormones into amino acids
c) Liver converts hormones into energy
d) Liver metabolizes hormones for removal from the body
d) Liver metabolizes hormones for removal from the body
(The liver catabolizes hormones, breaking them down into inactive forms that can be excreted from the body, which is important for maintaining hormonal balance.)
37
1. Why are triglycerides and cholesterol unable to circulate freely in the blood?
a) They are too large to pass through blood vessels
b) They are insoluble in an aqueous environment
c) They are quickly metabolized by the liver
d) They are bound to plasma proteinsb) They are
b) They are insoluble in an aqueous environment
(Triglycerides and cholesterol cannot circulate freely in the blood because they are insoluble in water.)
38
2. What are lipoproteins primarily composed of?
a) Triglycerides and cholesterol
b) Protein and carbohydrates
c) Phospholipids and cholesterol
d) Amino acids and nucleic acids
c) Phospholipids and cholesterol
(Lipoproteins are primarily composed of varying proportions of triglycerides, phospholipids, cholesterol, and protein.)
39
3. What is the role of protein in lipoproteins?
a) Providing energy for cellular functions
b) Transporting lipids to specific target cells
c) Regulating blood sugar levels
d) Initiating the breakdown of lipids
b) Transporting lipids to specific target cells
(Protein in lipoproteins is important for regulating the entry of lipids into specific target cells.)
40
4. How does the density of a lipoprotein relate to the percentage of lipid it contains?
a) Higher lipid percentage correlates with higher density
b) Higher lipid percentage correlates with lower density
c) Lipid percentage does not affect density
d) Density remains constant regardless of lipid percentage
b) Higher lipid percentage correlates with lower density
(In general, the higher the percentage of lipid in a lipoprotein, the lower its density.)
41
5. Which lipoprotein carries out the role of transporting dietary lipids from the intestines to other tissues?
a) VLDL
b) LDL
c) HDL
d) Chylomicrons
d) Chylomicrons
(Chylomicrons are responsible for transporting dietary lipids from the intestines to other tissues.)
42
6. Which lipoprotein is commonly referred to as "bad" cholesterol due to its association with cardiovascular disease risk?
a) Chylomicrons
b) VLDL
c) LDL
d) HDL
c) LDL
(LDL, or low-density lipoprotein, is commonly referred to as "bad" cholesterol due to its association with cardiovascular disease risk.)
43
7. What is the primary function of HDL (high-density lipoprotein)?
a) Transporting cholesterol to the liver for excretion
b) Transporting triglycerides to adipose tissue for storage
c) Transporting cholesterol to peripheral tissues for use in membrane synthesis
d) Transporting dietary lipids from the intestines to other tissues
a) Transporting cholesterol to the liver for excretion
(The primary function of HDL is to transport cholesterol from peripheral tissues to the liver for excretion.)
44
8. Which lipoprotein is synthesized by the liver and primarily transports endogenous triglycerides to peripheral tissues?
a) VLDL
b) LDL
c) HDL
d) Chylomicrons
a) VLDL
(VLDL, or very-low-density lipoprotein, is synthesized by the liver and primarily transports endogenous triglycerides to peripheral tissues.)
45
1. Which lipoprotein has the lowest density?
a) VLDL
b) LDL
c) Chylomicrons
d) HDL
c) Chylomicrons
(Chylomicrons have the lowest density among the lipoproteins.)
46
2. What is the primary function of chylomicrons?
a) Delivering cholesterol to peripheral tissues
b) Transporting triglycerides to adipose tissue
c) Transporting lipids from the gastrointestinal tract
d) Transporting cholesterol to the liver for breakdown
c) Transporting lipids from the gastrointestinal tract
(The primary function of chylomicrons is to transport newly absorbed lipids from the gastrointestinal tract.)
47
3. Where are VLDLs primarily synthesized?
a) Adipose tissue
b) Intestinal cells
c) Liver
d) Pancreas
c) Liver
(VLDLs are primarily synthesized in the liver.)
48
4. What happens to VLDLs at target cells?
a) They become chylomicrons
b) They are broken down by enzymes
c) They release triglycerides and become LDLs
d) They transport cholesterol to the liver
c) They release triglycerides and become LDLs
(At target cells, VLDLs release triglycerides, leading to their transformation into LDLs.)
49
5. What is the primary role of LDL?
a) Transporting triglycerides to peripheral tissues
b) Transporting cholesterol to peripheral tissues
c) Transporting lipids from the gastrointestinal tract
d) Transporting excess cholesterol to the liver
b) Transporting cholesterol to peripheral tissues
(The primary role of LDL is to deliver cholesterol to peripheral tissues.)
50
6. How is cholesterol primarily utilized in the body?
a) As a structural component of cell membranes
b) As a fuel for energy production
c) As a precursor for vitamin synthesis
d) As a building block for muscle tissue
a) As a structural component of cell membranes
(Cholesterol is primarily used as a structural component of cell membranes.)
51
7. How is excess cholesterol transported from peripheral tissues to the liver?
a) By VLDLs
b) By chylomicrons
c) By LDLs
d) By HDLs
d) By HDLs
(Excess cholesterol from peripheral tissues is primarily transported to the liver by HDLs.)
52
8. What is the primary purpose of HDL?
a) Transporting triglycerides to peripheral tissues
b) Transporting excess cholesterol from peripheral tissues to the liver
c) Synthesizing cholesterol in the liver
d) Storing cholesterol in adipose tissue
b) Transporting excess cholesterol from peripheral tissues to the liver
(The primary purpose of HDL is to transport excess cholesterol from peripheral tissues to the liver for breakdown.)
53
What health risks are associated with excess blood cholesterol levels (> 200 mg/dl)?
a) Increased risk of diabetes
b) Elevated risk of atherosclerosis and associated stroke and heart attack
c) Decreased risk of hypertension
d) Reduced risk of obesity
b) Elevated risk of atherosclerosis and associated stroke and heart attack
(Excess blood cholesterol levels (> 200 mg/dl) are linked to an elevated risk of atherosclerosis and associated cardiovascular events.)
54
Why are HDL often considered "good" cholesterol?
a) Because it promotes plaque formation in blood vessels
b) Because it mainly carries cholesterol destined for degradation
c) Because it increases the risk of heart attack
d) Because it transports cholesterol to peripheral tissues
b) Because it mainly carries cholesterol destined for degradation
(HDL is often considered "good" cholesterol because the cholesterol associated with it is mainly destined for degradation.)
55
What is the primary concern with excessive levels of LDL?
a) Decreased risk of atherosclerosis
b) Increased risk of blood clotting
c) Deposition of cholesterol in blood vessel walls
d) Accelerated breakdown of cholesterol
c) Deposition of cholesterol in blood vessel walls
(The primary concern with excessive levels of LDL is the deposition of cholesterol in blood vessel walls, which can lead to atherosclerosis.)
56
What specific form of LDL is associated with high risk of plaque formation in blood vessels?
a) LDL-alpha
b) LDL-beta
c) LDL-gamma
d) Lipoprotein (a)
d) Lipoprotein (a)
(Lipoprotein (a) is a high-risk form of LDL associated with plaque formation in blood vessels.)
57
Why is the ratio of HDL to LDL considered important?
a) It determines blood pressure levels
b) It regulates blood sugar levels
c) It influences the risk of atherosclerosis and cardiovascular diseases
d) It controls metabolic rate
c) It influences the risk of atherosclerosis and cardiovascular diseases
(The ratio of HDL to LDL is considered important because it influences the risk of atherosclerosis and cardiovascular diseases.)
58
How does high levels of HDL affect the risk of atherosclerosis?
a) It increases the risk
b) It decreases the risk
c) It has no effect
d) It promotes blood clot formation
b) It decreases the risk
(High levels of HDL decrease the risk of atherosclerosis by promoting the removal of cholesterol from blood vessels.)
59
What is the primary function of LDL in the body?
a) Transporting cholesterol to peripheral tissues
b) Transporting cholesterol to the liver for degradation
c) Promoting the breakdown of triglycerides
d) Initiating the synthesis of steroid hormones
a) Transporting cholesterol to peripheral tissues
(The primary function of LDL is to transport cholesterol to peripheral tissues.)
60
Which cholesterol is mainly responsible for deposition of cholesterol in blood vessel walls?
a) HDL
b) LDL
c) VLDL
d) Chylomicrons
b) LDL
(LDL is mainly responsible for the deposition of cholesterol in blood vessel walls, contributing to atherosclerosis.)
61
1. How do saturated fatty acids influence cholesterol levels?
a) They promote catabolism and excretion of cholesterol
b) They inhibit liver synthesis of cholesterol
c) They stimulate liver synthesis of cholesterol
d) They decrease LDL and increase HDL
c) They stimulate liver synthesis of cholesterol
(Saturated fatty acids promote liver synthesis of cholesterol.)
62
2. What effect do unsaturated fatty acids have on cholesterol metabolism?
a) They inhibit cholesterol excretion
b) They decrease LDL levels
c) They stimulate liver synthesis of cholesterol
d) They promote catabolism and excretion of cholesterol
d) They promote catabolism and excretion of cholesterol
(Unsaturated fatty acids promote catabolism and excretion of cholesterol.)
63
3. Despite being unsaturated, what is the effect of trans fats on cholesterol levels?
a) They decrease LDL and increase HDL
b) They decrease liver synthesis of cholesterol
c) They promote catabolism and excretion of cholesterol
d) They stimulate an increase in LDL and decrease HDL
d) They stimulate an increase in LDL and decrease HDL
(Trans fats, despite being unsaturated, stimulate an increase in LDL and decrease HDL.)
64
4. Which organ is the most important source of cholesterol synthesis?
a) Pancreas
b) Kidneys
c) Liver
d) Intestines
c) Liver
(The liver is the most important source of cholesterol synthesis.)
65
5. How does the consumption of saturated fatty acids affect cholesterol excretion?
a) It promotes catabolism and excretion of cholesterol
b) It inhibits cholesterol excretion
c) It decreases liver synthesis of cholesterol
d) It increases HDL and decreases LDL
b) They inhibit cholesterol excretion
(The consumption of saturated fatty acids inhibits cholesterol excretion.)
66
6. What is the primary effect of unsaturated fatty acids on cholesterol metabolism?
a) Inhibiting cholesterol excretion
b) Stimulating liver synthesis of cholesterol
c) Promoting catabolism and excretion of cholesterol
d) Increasing LDL levels
c) Promoting catabolism and excretion of cholesterol
(The primary effect of unsaturated fatty acids on cholesterol metabolism is promoting catabolism and excretion of cholesterol.)
67
. How do trans fats compare to saturated fatty acids in terms of LDL levels?
a) They have a similar effect on LDL levels
b) They decrease LDL levels
c) They have a greater effect on LDL levels
d) They have no effect on LDL levels
c) They have a greater effect on LDL levels
(Trans fats have a greater effect on LDL levels compared to saturated fatty acids.)
68
Which type of fatty acids promotes the highest increase in LDL and decrease in HDL?
a) Saturated fatty acids
b) Monounsaturated fatty acids
c) Polyunsaturated fatty acids
d) Trans fats
d) Trans fats
(Trans fats promote the highest increase in LDL and decrease in HDL compared to other types of fatty acids.)
69
1. Where is the thyroid gland located in the body?
a) Above the larynx
b) Below the trachea
c) Adjacent to the lungs
d) Behind the esophagus
1. b) Below the trachea
70
2. What is the shape of the thyroid gland?
a) Circular
b) Oval
c) Butterfly-shaped
d) Rectangular
2. c) Butterfly-shaped
71
3. How many lobes does the thyroid gland consist of?
a) One
b) Three
c) Four
d) Two
3. d) Two
72
4. How are the two lobes of the thyroid gland connected?
a) By a vein
b) By a nerve
c) By an artery
d) By an isthmus
4. d) By an isthmus
73
5. Which arteries supply blood to the thyroid gland?
a) Internal carotid arteries
b) External carotid arteries
c) Superior and inferior thyroid arteries
d) Subclavian arteries
5. c) Superior and inferior thyroid arteries
74
6. What is the size of the thyroid gland relative to other endocrine glands in the body?
a) It is the smallest
b) It is the second largest
c) It is the largest
d) It is the third largest
6. c) It is the largest
75
7. What is the main function of the thyroid gland?
a) Regulation of blood sugar levels
b) Production of insulin
c) Regulation of metabolism
d) Production of adrenaline
7. c) Regulation of metabolism
76
8. How does the blood supply to the thyroid gland compare to other organs?
a) It is supplied by a sparse blood supply
b) It is supplied by a rich blood supply
c) It is supplied by a moderate blood supply
d) It is supplied by an inconsistent blood supply
8. b) It is supplied by a rich blood supply
77
What is the structural composition of the thyroid gland?
a) Solid masses called follicles
b) Hollow spherical follicles surrounded by follicle cells
c) Tubular structures filled with colloid
d) Squamous epithelial cells
b)Hollow spherical follicles surrounded by follicle cells. This describes the typical structure of the thyroid gland, with follicles containing colloid.
78
What is the primary product synthesized by follicle cells in the thyroid gland?
a) Insulin
b) Glucagon
c) Thyroglobulin
d) Cortisol
c) Thyroglobulin. Follicle cells produce thyroglobulin, a glycoprotein that serves as the precursor for thyroid hormone synthesis.
79
What is the function of the colloid found within the follicles of the thyroid gland?
a) Regulation of blood sugar levels
b) Storage of iodinated thyroglobulin
c) Production of calcitonin
d) Synthesis of insulin
b) Storage of iodinated thyroglobulin. The colloid within the follicles serves as a reservoir of iodinated thyroglobulin, which is the precursor for thyroid hormone.
80
What role do parafollicular cells play in the thyroid gland?
a) Production of thyroglobulin
b) Synthesis of thyroid hormone
c) Secretion of calcitonin
d) Storage of colloid
c) Secretion of calcitonin. Parafollicular cells, also known as C cells, produce calcitonin, a hormone involved in calcium homeostasis.
81
What is the principal secretory product of the thyroid follicles?
a) Triiodothyronine (T3)
b) Thyroxine (T4)
c) Calcitonin
d) Thyroglobulin
b) Thyroxine (T4). T4 is the principal secretory product of the thyroid follicles and contains four iodine molecules.
82
Which thyroid hormone is derived largely from T4 at target cells?
a) Thyroglobulin
b) Calcitonin
c) Triiodothyronine (T3)
d) Thyroxine (T4)
c) Triiodothyronine (T3). T3 is the more active thyroid hormone and is derived largely from T4 at target cells.
83
What transports secreted T4 and T3 throughout the body in the bloodstream?
a) Thyroid stimulating hormone (TSH)
b) Thyroxine binding globulin (TBG)
c) Triiodothyronine (T3)
d) Thyroid hormone receptor (TR)
b) Thyroxine binding globulin (TBG). TBG binds to T4 and T3, transporting them throughout the body in the bloodstream.
84
In which cells of the body does thyroid hormone have an effect?
a) Few exceptions such as the adult brain and spleen
b) Only in muscle cells
c) Only in nerve cells
d) Essentially every cell in the body
d) Essentially every cell in the body. With few exceptions, thyroid hormone affects essentially every cell in the body, influencing metabolism and growth.
85
What typically happens to T4 at target cells?
a) It is excreted from the body
b) It is converted to calcitonin
c) It is converted to T3
d) It is transported back to the thyroid gland
c) It is converted to T3. At target cells, much of the T4 is converted to the more active T3 by enzymes present in the cells.
86
Where do T3 and T4 bind within the nucleus of target cells?
a) Thyroid gland
b) Thyroxine binding globulin (TBG)
c) Thyroid hormone receptor (TR)
d) Triiodothyronine (T3)
c) Thyroid hormone receptor (TR). T3 and T4 bind to TR within the nucleus of target cells, initiating gene expression.
87
Why is T3 approximately 10 times more active than T4?
a) T3 has more iodine molecules
b) T3 has a higher affinity for TBG
c) T3 is converted to T4 at target cells
d) T3 binds more tightly to the thyroid hormone receptor (TR)
d) T3 binds more tightly to the thyroid hormone receptor (TR). T3 is approximately 10 times more active than T4 because it binds more tightly to TR, resulting in increased gene expression and metabolic activity.
88
What hormone is secreted by the anterior pituitary gland in response to falling thyroid hormone levels?
a) Thyroxine (T4)
b) Triiodothyronine (T3)
c) Thyroid stimulating hormone (TSH)
d) Thyroglobulin
c) Thyroid stimulating hormone (TSH). Falling thyroid hormone levels trigger the secretion of TSH by the anterior pituitary gland.
89
What is the initial response of the thyroid gland to TSH stimulation?
a) Resynthesizing thyroglobulin
b) Releasing stored thyroid hormone
c) Inhibiting TSH secretion
d) Decreasing blood flow to the thyroid gland
b) Releasing stored thyroid hormone. The initial response of the thyroid gland to TSH is to release stored thyroid hormone into the bloodstream.
90
What is the second response of the thyroid gland to TSH stimulation?
a) Inhibiting thyroid hormone synthesis
b) Decreasing blood flow to the thyroid gland
c) Resynthesizing thyroglobulin and replenishing the colloid
d) Converting T3 to T4
c) Resynthesizing thyroglobulin and replenishing the colloid. The second response of the thyroid gland to TSH is to resynthesize thyroglobulin and replenish the colloid, ensuring a future supply of thyroid hormone.
91
What is unique about the storage and release mechanism of the thyroid gland?
a) It stores hormone in the adrenal glands
b) It releases hormone directly into the bloodstream
c) It has enough hormone in colloid to support secretion for several months
d) It relies on constant synthesis without storage
c) It has enough hormone in colloid to support secretion for several months. Unlike many other endocrine glands, the thyroid gland has a unique mechanism where it stores enough hormone in colloid to support secretion for several months, allowing for a continuous supply of thyroid hormone even when synthesis is temporarily decreased.
92
ANP1107
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