Thyroid Hormones HW Questions Flashcards
1
Q
The thyroid gland is located inferior to the __________ and anterior to the _____________
A
larynx, trachea
2
Q
The hypothalamic pituitary axis for thyroid hormone is the hypothalamus secretes _________ which stimulates the anterior pituitary to release _________ which stimulates the thyroid gland to produce thyroid hormones T3 and T4
A
TRH, TSH
3
Q
The primary function of thyroid hormone is to ____________ metabolic rate of body
A
increase
4
Q
The final product of thyroid hormone synthesis during a cycle is approx _______ thyroxine and ________ triiodothyronine
A
93%, 7%
5
Q
The storage form of thyroid hormone is _______ and the bioactive form of thyroid hormone is ________
A
T4, T3
6
Q
What type of cell forms thyroid follicles?
A
cuboidal epithelial
7
Q
What hormones are produced by the thyroid gland?
A
T4, T3, and calcitonin
8
Q
How does the body maintain normal plasma levels of thyroid hormone?
A
negative feedback
9
Q
What dietary mineral is required to produce thyroid hormones?
A
iodide
10
Q
How does ingestion of too many iodides affect thyroid hormone production?
A
inhibits
11
Q
How does the thyroid gland get iodides into its follicular cells?
A
active pumping
12
Q
What hormone activates the process of iodide trapping?
A
TSH
13
Q
What type of thyroid cell secretes the colloid mixture?
A
thyroid follicle cells
14
Q
What is the main component of the colloid mixture?
A
thyroglobulin
15
Q
What is the main AA composition of thyroglobulin?
A
tyrosine
16
Q
What hormone stimulates the production of thyroglobulin?
A
TSH
17
Q
What enzyme is required to oxidize iodide?
A
thyroid peroxidase
18
Q
What is the organification process in synthesizing thyroid hormone?
A
binding iodine to tyrosine
19
Q
What enzyme is required for organification?
A
thyroid peroxidase
20
Q
What are the stages of organification?
A
formation of MIT and DIT
21
Q
What is coupling of idotyrosine units?
A
cleavage of a DIT and MIT unit or cleavage of a DIT and DIT unit
22
Q
What type of enzyme is required for the coupling process?
A
proteolytic
23
Q
What effect does high consumption of goitrogenic veggies have on thyroid hormone synthesis?
A
block thyroid peroxidase
24
Q
How much of the iodinates tyrosine MIT and DIT molecules are recycled each secretion cycle?
A
75%
25
What enzyme is required to cleave iodine from the MIT and DIT molecule not coupled during a secretion cycle?
thyroid deiodinase
26
What is the storage capacity of thyroid hormone in thyroid gland follicles?
2-3 months
27
approx 90% of all circulating thyroid hormone is bound to
thyroxine binding globulin
28
How often is T4 released into the body?
about every 6 days
29
How often is T3 released into circulation?
about every 24 hours
30
How much of the circulating T4 is deiodinated by the liver over a few days?
50%
31
Where does T3 bind to a receptor inside the target cell?
nucleus
32
Where on the DNA does the thyroid hormone receptor complex bind?
hormone response segment
33
What does the docking of T3 hormone receptor complex on the DNA stimulate?
transcription
34
Would hypothyroidism or hyperthyroidism patients always be tired?
hypothyroidism
35
Would hypothyroidism or hyperthyroidism patients have tachycardia?
hyperthyroidism
36
Would hypothyroidism or hyperthyroidism patients have weight loss with increased appetite?
hyperthyroidism
37
Would hypothyroidism or hyperthyroidism patients increase metabolism 60-100% above normal?
hyperthyroidism
38
Would hypothyroidism or hyperthyroidism patients have impotence?
hyperthyroidism
39
Would hypothyroidism or hyperthyroidism patients have decreased metabolism rate by 50%?
hypothyroidism
40
Would hypothyroidism or hyperthyroidism patients have weight gain while decreasing appetite?
hypothyroidism
41
Would hypothyroidism or hyperthyroidism patients have diarrhea?
hyperthyroidism
42
Would hypothyroidism or hyperthyroidism patients have brain fog?
hypothyroidism
43
Would hypothyroidism or hyperthyroidism patients have slow skeletal bone growth?
hypothyroidism
44
Would hypothyroidism or hyperthyroidism patients have increased cardiac output by 60%?
hyperthyroidism
45
Would hypothyroidism or hyperthyroidism patients have amenorrhea?
hyperthyroidism
46
Would hypothyroidism or hyperthyroidism patients have decreased plasma conc. of cholesterol and TGs?
hyperthyroidism
47
How does normal levels of thyroid hormone effect metabolism?
increases number and activity of mitochondria
48
How does thyroid hormone increase cardiac output?
increases blood flow back to heart (end diastolic filling)
49
What does normal levels of thyroid hormone do to heart rate?
maintains normal heart rate
50
Why does hyperthyroidism not effect mean arterial pressure?
diastolic pressure is lowered in proportion to the rise in systolic pressure
51
How does normal levels of thyroid hormone effect cognitive abilities?
increases cerebration (thinking)
52
What is the role of thyroid hormone during fetal development and the first few years of life?
promotes brain growth and development
53
How does thyroid hormone increase plasma glucose?
enhance liver gluconeogenesis
54
How does thyroid hormone increase serum fatty acids?
mobilizes fatty acids from adipose cells
55
Why does thyroid hormone increase glucose and fatty acid levels in blood?
to provide products for energy production
56
How does thyroid hormone effect the number of LDL receptors on hepatocytes?
increases number
57
How does thyroid hormone effect serum levels of cholesterol?
decreases it
58
Thyroid hormone stimulates the liver to secrete cholesterol into....
bile
59
What effect does normal levels of thyroid hormone have on bone?
promotes growth
60
What effect does normal levels of thyroid hormone have on skeletal muscle?
increases tone, strength, and energy
61
How does normal levels of thyroid hormone effect activity of other endocrine glands?
increases rate of secretion while increasing demand
62
Would hypothyroidism or hyperthyroidism patients have decreased libido?
hypothyroidism
63
Would hypothyroidism or hyperthyroidism patients have polymenorrhea?
hypothyroidism
64
Would hypothyroidism or hyperthyroidism patients have bradycardia?
hypothyroidism
65
Would hypothyroidism or hyperthyroidism patients have skeletal muscle weakness?
hyperthyroidism
66
Would hypothyroidism or hyperthyroidism patients have constipation?
hypothyroidism
67
Would hypothyroidism or hyperthyroidism patients have increased plasma conc. of cholesterol and TGs?
hypothyroidism
68
Would hypothyroidism or hyperthyroidism patients have oligomenorrhea?
hyperthyroidism
69
Would hypothyroidism or hyperthyroidism patients have skeletal muscle slow to relax after contraction?
hypothyroidism
70
Would hypothyroidism or hyperthyroidism patients have atherosclerosis?
hypothyroidism
71
Would hypothyroidism or hyperthyroidism patients have insomnia?
hyperthyroidism
72
Would hypothyroidism or hyperthyroidism patients have slow bone growth?
hypothyroidism
73
Would hypothyroidism or hyperthyroidism patients muscle tremor?
hyperthyroidism
74
Would hypothyroidism or hyperthyroidism patients have excessive skeletal bone growth?
hyperthyroidism
75
Would hypothyroidism or hyperthyroidism patients have rapid mental activity?
hyperthyroidism
76
The hypothalamic _______________ nucleus produces thyrotropin releasing hormone (TRH)
paraventricular
77
Which secondary messenger system does TRH use to stimulate thyroid follicle cells?
phospholipase C
78
How does TRH initiate the second messenger system?
binds to a GPCR
79
How does DAG activate in the second messenger system?
protein kinase
80
What does activated protein kinase stimulate in the second messenger system initiated by TRH?
synthesis and secretion of TSH
81
What is the role of IP3 in the second messenger system?
release intracellular calcium
82
What does the calcium calmodulin complex activate in the phospholipase C second messenger system?
synthesis and secretion of TSH
83
Which second messenger system does TSH use to stimulate the thyroid?
cAMP
84
What type of receptor does TSH bind with on the thyroid follicular cell membrane?
GPCR
85
What is the 1st messenger in cAMP second messenger system that stimulates thyroid hormone production?
TSH
86
What enzyme in the cAMP second messenger system converts ATP into cAMP?
adenylate cyclase
87
Which enzyme is activated by cAMP in the second messenger system?
protein kinase
88
What does activated protein kinase stimulate in the second messenger system initiated by TSH?
synthesis and secretion of thyroid hormone
89
Which autoimmune disorder is the most common cause of hyperthyroidism?
Grave's disease
90
How does the immune system affect the thyroid gland in Grave's disease?
it produces thyroid stimulating antibodies (TSAb) called thyroid stimulating immunoglobulin (TSI)
91
How does TSAb/TSI affect thyroid follicular cells?
stimulates thyroid hormone production
92
How long does TSAb/TSI cause the thyroid gland to produce and secrete thyroid hormone in a cycle?
about 12 hours
93
How long does TSH stimulate the thyroid gland to produce and secrete thyroid hormones in a cycle?
about 1 hour
94
What is the rate of thyroid hormone secretion when under the influence of TSAb/TSI?
increases 5-15x above normal
95
Does Grave's disease damage the thyroid gland?
no
96
How does Grave's disease affect the size of the thyroid gland?
increases it
97
What would the levels of TSH and thyroid hormone be in a person with Grave's disease?
TSH low, thyroid hormones high (T3/T4)
98
What eye condition is commonly seen with Grave's disease?
exophthalmos
99
What causes a goiter in the case of hyperthyroidism?
overproduction of thyroid hormones
100
Which non-autoimmune condition causes the thyroid gland to increase secretion of thyroid hormones without TSH stimulation?
thyroid adenoma
101
What is the underlying cause of most hyperthyroid symptoms?
abnormally high metabolic rate
102
Which anterior pituitary cell produces TSH?
thyrotropes
103
Which hormone increases all known secretory activity of thyroid cells?
TSH
104
What is the most important early effect of TSH?
secretion of thyroid hormone
105
How does TSH stimulate secretion of thyroid hormone?
activates proteolysis of iodinated thyroglobulin
106
How does TSH effect the size of thyroid follicle cells?
increase size
107
What condition causes inflammation of the thyroid gland?
hashimoto's
108
What is the most common cause of hypothyroidism?
hashimoto's
109
What causes hashimoto's disease?
autoimmunity
110
How does hashimoto's disease cause inflammation of the thyroid?
T cells (killer and helper) damage thyroid follicular cells
111
How do hashimoto's symptoms initially manifest?
patient cycles between hypothyroidism and hyperthyroidism symptoms
112
What happens to the thyroid hormones stored in the colloid mixture with Hashimoto's?
dumped into circulation
113
Why are blood tests for thyroglobulin or peroxidase Abs used to diagnose early hashimoto's disease?
thyroglobulin and peroxidase should not be in blood circulation
114
What will blood test show in advanced hashimoto's?
high TSH, low thyroid hormones (T3/T4)
115
What causes a goiter in the case of hashimoto's?
inflammation
116
What dietary conditions cause an endemic colloid goiter in the Great Lakes region of the US?
soil deficiency of iodides
117
How does a person develop an endemic goiter?
thyroid gland continues to produce thyroglobulin
118
What factors can lead to iodine deficiency?
deficiency of peroxidase and or deiodinase
119
What does a congenital lack of a thyroid gland cause?
cretinism
120
What is the typical IQ of a child born with cretinism?
<25
121
Damage to anterior pituitary _____________ could cause hypothyroidism
thyrotropes
122
What is myxedema?
most severe form of hypothyroidism
123
How much thyroid hormone is produced with myxedema?
almost 0
124
Which condition is associated with non-pitting edema caused by accumulation of sub-dermal mucopolysaccharides?
myxedema
