12/4: Thyroid, Parathyroid Pancreas, & Adrenal Glands Flashcards
(133 cards)
1
Q
Where is the thyroid gland found?
A
Anterior to tracheal rings 2-3
2
Q
What are the right and left lobes separated by?
A
An isthmus
3
Q
What does each thyroid lobe consist of?
A
Follicles (structural and functional unit) filled with colloid
4
Q
Describe the epithelium of the thyroid follicle
A
Single layer
Cuboidal to columnar
5
Q
What does the thyroid follicle surround?
A
Central lumen of colloid
6
Q
What is the thyroids product?
A
Thyroglobulin
7
Q
Where is thyroglobulin stored?
A
Central follicular lumen
8
Q
What does the follicular epithelium have?
A
Receptors for thyroid stimulating hormone (TSH)
9
Q
Where does TSH come from?
A
Anterior pituitary
10
Q
What does the thyroid control?
A
both synthesis (exocrine)
& secretion (endocrine) of
thyroid hormones
11
Q
What is the process of synthesis in the exocrine portion?
A
- Uptake of amino acids
& iodide into the cell. - Thyroglobulin (TGB)
synthesized on RER - Addition of iodine to
tyrosine residues of
TGB, released into the
lumen by exocytosis
12
Q
How are the thyroid hormones stored?
A
Extracellularly as thyroglobulin
13
Q
What is the thyroid inhibited by?
A
Anti-thyroid drugs
14
Q
What is a result of TSH stimulus?
A
Endocytosis and digestion of colloid
15
Q
What do colloid droplets fuse with?
A
Lysosomes
16
Q
What do digestive enzymes breakdown?
A
TGB, releasing T3, T4, and iodine
17
Q
What is T4 secreted by?
A
Thyroid
18
Q
Is the T3 or T4 more potent?
A
T3
19
Q
How to T3 and T4 diffuse?
A
Through membrane into capillary
20
Q
What is capillary transport facilitated by?
A
Thyroxine-binding protein
21
Q
What does the thyroid hormone stimulate?
A
Basic metabolic rate
22
Q
What does the thyroid hormone augment?
A
- Thermogenesis
- Glucose production
23
Q
What is the thyroid hormone required for?
A
Normal development of CNS
24
Q
Where are parafollicular or ‘c’ cells found?
A
In isolated clusters between follicles or within the follicular epithelium
25
What do parafollicular or 'c' cells produce?
Calcitonin
26
What does calcitonin do?
Decrease calcium concentration by increasing osteoblast activity and decreasing bone resorption (osteoclasts)
Calci- tone in (calcium)
Calci - bone in (osteoblasts)
27
What does calcitonin bind to?
Receptor on osteoclast
28
What is hypercalcemia?
Blood levels of Ca2+ stimulates calcitonin secretion
29
What is hyperthyroidism?
Excessive production of TSH
30
What are symptoms of hyperthyroidism?
increased metabolic rate,
weight loss, hyperactivity and heat intolerance
31
What are common causes of hyperthyroidism?
* Excessive stimulation by adenohypophysis
* Loss of feedback control by thyroid gland (Graves’
disease)
* Ingestion of T4 (used for weight loss)
32
What is Grave's disease caused by?
Autoimmune disorder that produces antibodies to the receptors for TSH on the follicular epithelium. Antibodies bind to the
receptor and chronically stimulate it. The result is too much circulating thyroid hormone.
33
What are standard symptoms of grave's disease?
Standard symptoms plus exopthalamos (collagen deposition
posterior to eyeball the TSH-R is also found in orbital fat)
34
What is treatment for grave's disease?
Surgical removal, radioactive iodine
35
What is the post treatment regimen for grave's disease?
Supplementation of thyroid hormones
36
What is hypothyroidism caused by?
Insufficient production of thyroid hormone
37
What are symptoms for hypothyroidism?
low metabolic rate, feeling of being cold, weight gain (some patients) and
photophobia (TAED- thyroid associated eye
disease)
38
What are causes of hypothyroidism?
decreased iodine intake, loss of pituitary stimulation, post-therapeutic or destruction of the thyroid by the immune system
39
What's treatment for hypothyroidism?
Oral thyroid medication
40
What is endemic goiter caused by?
Iodine deficiency
41
What does the pituitary gland do in relation to PSH in a patient who has goiter?
Releases more TSH but the gland cannot respond
42
How can goiter be avoided?
By adding iodine to the diet
- iodine salt
43
What is the treatment for goiter?
Surgery
44
What are the two types of secretory cells that the parathyroid secretes?
Chief cells
Oxyphil cells
45
What do chief cells secrete?
Parathyroid hormone
46
Fatty infiltration of the parathyroid gland is more common in?
Older individuals
47
What is the function of oxyphil cells?
Unknown; ?inactive chief cells
48
What is the parathyroid hormone secreted by in response to?
Chief cells; low blood Ca level
49
What does the parathyroid hormone regulate?
Calcium and phosphate balance by increasing blood Ca level/decreasing phosphate levels
50
What does the PTH act on and promote?
Osteoblasts to promote osteoclasts -> increase in circulating calcium levels
51
What does the parathyroid hormone act on?
Renal tubules to stimulate resorption of calcium
52
What does the PTH control rate of?
Ca uptake in GI tract by regulating production of Vitamin D (kidneys)
53
What does vitamin D sitmulate?
Cells of intestinal mucosa to absorb Ca and synthesize calbindin (carrier protein)
54
What is PTH activity balanced by?
Calcitonin
55
What does the PTH stimulate resorption of?
Mineralized bone by osteoclasts, release of Ca into the blood
56
What does calcitonin promote?
Osteogenesis
57
What does calcitonin act on?
Osteoclasts to inhibit bone resorption/ Ca release
58
What is hypoparathyroidism a deficiency in?
Secretion of PTH
59
What are the blood and bone calcium levels in hypoparathyroidism?
Blood calcium is low, bone calcium is not released
60
What does a Ca deficiency result in?
spontaneous depolarization of neurons & muscle fibers resulting in tetany
61
What are the blood calcium levels in hyperparathyroidism?
High (hypercalcemia)
62
What does hyperparathyrodiism result in?
Bone loss- can result in osteomalacia
63
What does hyperparathyroidism cause?
Abnormal calcium deposition in arteries and kidneys
64
Where are centroacinar cells found?
Lumen of pancreatic acini
65
What are the cells of intercalated ducts?
Centroacinar cells
66
Where are islets of langerhans embedded within?
Exocrine tissue
67
Islets of langerhans are a part of what portal system?
Insuloacinar portal system
68
Describe the flow from arterioles to capillaries
Afferent arteriole -> fenestrated capillaries -> efferent capillaries
69
What do efferent capillaries (venules) supply?
Exocrine pancreatic acini
70
What do efferent capillaries allow direct action of?
Hormones on exocrine portion
71
What are the 3 main cell types of islet cells?
Alpha, beta, and gamma
72
What do alpha cells secrete?
Glucagon
73
What do alpha cells do?
↑ blood glucose, stimulates glucogenesis & glycogenolysis
74
What do beta cells secrete?
Insulin
75
What do beta cells do?
↓ blood glucose & stimulates intracellular glycogen synthesis
76
What do gamma cells secrete?
Somatostatin
77
What do gamma cells do?
inhibits both insulin &
glucagon production
78
What do miscellaneous cell types secrete?
vasoactive intestinal peptide (VIP) & pancreatic polypeptide (PP)
79
What deficiency causes diabetes mellitus?
insulin deficiency/abnormality
80
What is diabetes mellitus characterized by?
hyperglycemia (↑ blood
glucose) & glucosuria (glucose in urine)
81
What is considered juvenille diabetes?
Type I (Decrease insulin production)
82
What is considered adult osnset diabetes?
Type II (↓ # of insulin receptors or ↓ responsiveness)
83
What is the adrenal gland also known as?
Suprarenal gland
84
Where is the adrenal gland located?
Superior to kidneys
85
What are adrenal glands covered by?
Thin connective tissue capsule
86
Describe the endocrine gland in mammals
Single, endocrine gland with two different embryological origin
87
What is the adrenal gland regulated by?
ACTH secreted by anterior pituitary
88
What are steroid hormones structurally related to?
Cholesterol precursor
89
What are the three functional classes of adrenal hormones?
Mineralcorticoids
Glucocorticoids
Sex hormones
90
What are examples of mineralcorticoids
Aldosterone (RAAS pathway)
91
What do mineralcorticoids do?
Control electrolyte and fluid balance
92
What do mineralcorticoids regulate?
- Na & K levels via Na pumps, especially in renal
tubules
- blood pressure via JGA
93
What are examples of glucocorticoids?
Cortisol
94
What do glucocorticoids stimulate?
- gluconeogenesis & glycogenolysis—both ↑
blood glucose
- ↑ metabolism & breakdown of proteins,
carbohydrates, & lipids
95
What are examples of sex hormones?
Androgens
96
What do sex hormones do?
Stimulate gonadal production (small amount of them)
97
What are the three layers (from superficial to deep) of the adrenal cortex?
Zona glomerulosa
Zona fasciculata
Zona reticularis
98
What does the zona glomerulosa secrete?
Secretes mineralocorticoids, e.g.,
aldosterone
99
What does the zona fasciculata secrete?
Secrete glucocorticoids; e.g., cortisol
Stress promotes secretion of cortisol,
which ↓ immune response
Small amounts of androgens also
secreted
100
What cells does the zona fasciculata contain?
Spongiocytes
101
What does the zona reticularis secrete?
small quantities of androgens & glucocorticoids
102
Where does medulla have direct blood supply and sinusoids from?
Cortex (long cortical aa)
103
What are mineralocorticoids produced in response to?
Angiotensin II (also ACTH)
104
What is the zona glomerulosa involved in?
electrolyte (Na+ and K+) and water balance
105
What does the zona fasiculata regulate?
CHO, protein and fat metabolism
106
What does the liver do?
promote uptake/use of fatty acids, amino acids & CHO
107
What kind of effect do other tissues have?
Catabolic effect
108
What can the zona fasiculata do to the immune system?
Decrease number of circulating lymphocytes
109
How are the cells arranged in the zona reticularis?
Irregular cords that form an anastomosing network
110
What is it called if you have hypoadrenocorticism?
Addison's disease
111
What is addison's disease?
Failure of adrenal cortex to produce hormone (mineralo- and glucocorticoids)
112
What is addison's disease due to?
Atrophy of gland (often caused by autoimmune disease)
113
What does a decrease in aldosterone cause?
↓ ECF volume,
hyponatremia, hyperkalemia, mild acidosis
=> shock, death
(aka Addisonian crisis)
114
What does a decrease in cortisol cause?
↓ blood glucose
115
What is treatment for addison's disease?
exogenous administration of mineralocorticoids & glucocorticoids
(Fludrocortisone & cortisol)
116
What is an example of hyperadrenocorticism?
Cushing's disease
117
What is primary hyperadrenocorticism?
adrenal hyperadrenocorticism
118
What is adrenal hyperadrenocorticism due to?
general adrenal hyperplasia
or functional tumor of adrenal cortex
=> excess cortisol secretion
119
What is secondary hyperadrenocorticism?
pituitary hyperadrenocorticism, aka
“Classical form”
120
What is hyperadrenocorticism caused by?
↑ ACTH from anterior pituitary
(pituitary tumor, e.g., adenoma or
carcinoma)
or other cortisol-producing tumor
121
What does an ↑ in ACTH secretion cause?
- Adrenal hyperplasia & excess cortisol
secretion
- other cortisol producing tumor
122
What are Regarded as modified sympathetic
postganglionic neurons?
Chromaffin cells
123
What are Lost axons & dendrites during embryonic development & have become secretory cells?
Chromaffin cells
124
What kind of granules do chromaffin cells have?
Secretory granules of
Epinephrine or Nor-
epinephrine
125
What are catecholamines secreted in response to?
Intense emotional reactions
- defensive reaction to stress
126
What are symptoms of a release of catecholamines?
* Increase heart rate
* Dilates blood vessels supplying cardiac &
skeletal muscle
* Bronchiole dilation
* Vasoconstriction of blood vessels
supplying GI tract, kidneys, skin...
127
What is pheochromocytoma?
Benign tumor of the chromaffin cells
128
What secretion does pheochromocytoma have?
Episodic of epinephrine and Nor-e
129
What are signs and symptoms of pheochromocytoma?
those of
sympathetic nervous system
hyperactivity: elevated heart rate,
BP, palpitations, diaphoresis,
anxiety, headaches, nausea
130
What does pheochromocytoma precipitate?
Because of excessive
catecholamine secretion,
pheochromocytomas may
precipitate life-threatening
hypertension or cardiac
arrhythmias
131
Up to 25% of pheochromocytomas may be...
Familial
132
What is the Hatfield-McCoy Feud partly explained by?
Rare-inherited disease (von Hippel-Landau) which led to rage and violence
133
Roughly 3/4 of the affected McCoys have?
pheochromocytomas -- tumors of the adrenal gland
