Endocrine part 2 - thyroid, parathyroid, pancreas, adrenal Flashcards
(79 cards)
1
Q
Where is the thyroid gland located?
A
anterior to tracheal rings 2-3
2
Q
What separates the right and left lobes of the thyroid?
A
isthmus
3
Q
What does each lobe of the thyroid gland consist of?
A
follicles filled with colloid
4
Q
What are the characteristics of a thyroid follicle?
A
- single layer of epithelium
- cuboidal or columnar
- central lumen of colloid
- thyroglobulin
5
Q
Follicular epithelium has receptors for __________________
A
thyroid stimulating hormone (TSH) from anterior pituitary
6
Q
What does the thyroid epithelium control?
A
synthesis (exocrine) and secretion (endocrine) of thyroid hormones
7
Q
What is the process of exocrine part of thyroid hormone synthesis?
A
- uptake amino acids and iodine
- thyroglobulin (TGB) synthesied on rough ER
- addition of idoine to tyrosine residues of TBG
- released into lumen via exocytosis
8
Q
Thyroid hormones are stored extracellularly as _______
A
thyroglobulin (TGB)
9
Q
What is the process of the endocrine part of thyroid hormone synthesis?
A
- endocytosis/digestion of colloid
- colloid droplets fuse with lysosomes
- digestive enzymes breakdown TGB releasing T3, T4, and iodine
- T3 and T4 diffuse through membrane into capillary
10
Q
Which thyroid hormone is secreted more and which is more potent?
A
more T4 is secreted
T3 is 3-4x more potent
11
Q
What are the functions of thyroid hormone?
A
- stimulates basic metabolic rate
- augments thermogenesis
- augments glucose production
- required for normal development of CNS
12
Q
Where are parafollicular/ C cells found?
A
isolated clusters between follicles or within the follicular epithelium
13
Q
What do parafollicular/ C cells produce?
A
calcitonin
14
Q
What does calcitonin do?
A
decrease calcium concentration by inhibiting bone resorption
15
Q
What does hypercalcemia do to calcitonin secretion?
A
stimulates calcitonin due to high blood levels of calcium
16
Q
What are the symptoms of hyperthyroidism?
A
increased metabolic rate
weight loss
hyperactivity
heat intolerance
17
Q
What is the disease associated with excessive production of TSH?
A
hyperthyroidism
18
Q
What is the main symptoms of Grave’s disease?
A
exopthalamos (collagen deposition posterior to eyeball)
19
Q
What causes hyperthyroidism?
A
- excessive stimulation by adenophyophysis
- loss of feedback control by thyroid gland (grave’s disease)
- ingestion of T4
20
Q
What causes grave’s disease?
A
- autoimmune disorder that produces antibodies to the receptors for TSH on the follicular epithelium
- antibodies bind to receptor and chronically stimulate it
- results in too much circulating thyroid hormone
21
Q
What are the symptoms of hypothyroidism?
A
low metabolic rate
feeling of being cold
weight gain
photophobia (thyroid associated eye disease)
22
Q
What disease is caused by insufficient production of thyroid hormone?
A
hypothyroidism
23
Q
What can cause hypothyroidism?
A
- decreased iodine intake
- loss of pituitary stimulation
- post-therapeutic or destruction of thyroid by immune system
24
Q
What is the treatment for hypothyroidism?
A
oral thyroid medication
25
Endemic goiter is caused by ________________________
iodine deficiency
26
How can goiter be avoided?
adding iodine to the diet
27
What are the two types of secretory cells in the parathyroid gland?
chief cells
oxyphil cells
28
What is the most abundant secretory cell in the parathyroid gland?
chief cell
29
What do the chief cell secrete in the parathyroid?
parathyroid hormone
30
Which parathyroid secretory cell contains a large number of mitochondria?
oxyphil cell
31
Parathyroid hormone is secreted by chief cells in response to _______________________________
low blood calcium level
32
Parathyroid hormone regulates calcium and phosphate how?
increasing blood Ca levels
decreasing phosphate levels
33
______ acts on osteoblasts to promote osteoclast activity which increases calcium levels
PTH (parathyroid hormone)
34
_____ acts on renal tubules to stimulate resorption of calcium
PTH (parathyroid hormone)
35
Parathyroid hormone controls the rate of calcium uptake in the GI by regulating the production of ______________
vitamin D in kidneys
36
What stimulates cells of intetinal mucosa to absorb calcium and synthesizes calbindin?
vitamin D
37
What are the characteristics of hypoparathyroidism?
- deficiency in secretion of PTH
- blood calcium low
- bone calcium not released
- spontaneous depolarization of neurons and muscle fibers (tetany)
38
What are the characteristics of hyperparathyroidism?
- high blood calcium levels
- bone loss (osteomalacia)
- abnormal calcium deposition in arteries and kidneys
39
Where are centroacinar cells found?
only in lumen of pancreatic acini
40
Where are islets of langerhans?
embedded within exocrine tissue of pancreas
41
How many islet of langerhans in a pancreas?
around 1 million
42
What portal system is involved in the islets of langerhans?
insuloacinar portal system
43
What is the pathway of blood through the islets of langerhans?
afferent arteriole -> fenestrated capillaries -> efferent capillaries
44
Which capillaries in the islet of langerhans supply exocrine pancreatic acini?
efferent capillaries
45
What are the three main cells in the islet of langerhans?
a-cells
B-cells
S-cells
46
What are the characteristics of a-cells in the islet of langerhans?
- 15-20%
- secrete glucagon
- increase blood glucose
- stimulates glucogenesis and glycogenesis
47
What are the characteristics of B-cells in the islet of langerhans?
- 70%
- secrete insulin
- decrease blood glucose
- stimulates intracellular glycogen synthesis
48
What are the characteristics of S-cells in the islet of langerhans?
- 5-10%
- secrete somatostatin
- inhibits both insulin and glucagon production
49
What is diabetes mellitus?
insulin deficiency/abnormality
50
What does type 1 diabetes cause?
decreased insulin production
51
What does type 2 diabetes cause?
decrease number of insulin receptors or decrease in responsiveness
52
What are the two main symptoms of diabetes mellitus?
hyperglycemia
glucosuria (glucose in urine)
53
What hormone regulates the adrenal gland?
ACTH from the anterior pituitary
54
Steroid hormones structurally related to ___________ precursor
cholesterol
55
What are the three functional classes of adrenal hormones?
mineralocorticoids
glucocoricoids
sex hormones
56
What are the characteristics of mineralocorticoids?
aldosterone
- control electrolyte and fluid balance
- regulate Na and K levels via Na pumps (in renal tubuels)
- regulates blood pressure via JGA
57
What are the characteristics of glucocorticoids?
cortisol
- stimulates gluconeogenesis and glycogenolysis
- increases blood glucose
- increases metabolism of proteins, carbs, lipids
58
What are the characteristics of sex hormones?
androgens
- small amount
59
What are the three layers of the adrenal cortex?
zona glomerulosa (15%)
zona fasciculata (80%)
zone reticularis (5%)
60
Which layer of the adrenal cortex secretes mineralocorticoids (aldosterone)?
zona glomerulosa
61
Which layer of the adrenal cortex secretes glucocorticoids (cortisol)?
zona fasciculata
62
Which layer of the adrenal cortex secretes small quanitities of androgens and glucocorticoids?
zona reticularis
63
Which layer of the adrenal cortex contains spongiocytes?
zona fasciculata
64
The zona glomerulosa produces aldosterone (mineralocorticoids) in response to what?
angiotension II
ACTH
65
Which layer of the adrenal cortex is involved in electrolyte and water balance?
zona glomerulosa
66
Which layer of the adrenal cortex have cells that contain lipid droplets in cytoplasm and have spongiocytes?
zona fasiculata
67
What is the zona fasiculata involved in?
- glucocorticoids
- regulate CHO, protein, and fat
- liver
- catabolic effect in other tissues
- suppress the immune system
68
What are the characteristics of the zona reticularis?
- cells arranged in irregular cords that frm an anastomosing network
69
What disease has hypoadrenocorticism?
addison's disease
70
What disease has hyperadrenocorticism?
cushing's disease
71
What are the characteristics of hypoadrenocorticism (Addison's disease)?
- failure of adrenal cortex to produce hormone
- atrophy of gland
- decreased aldosterone
- decreased cortisol
- decreased blood glucose
72
What are the characteristics of hyperadrenocorticism (Cushing's disease)?
primary
- due to general adrenal hyperplasia or functional tumor
- excess cortisol secretion
secondary
- increased ATCH
- adrenal hyperplasia and excess cortisol secretion
73
What cells are in the adrenal medulla?
chromaffin cells
74
Chromaffin cells in the adrenal medulla secrete what?
epinephrine
nor-epinephrine
75
What chromaffin cells in the adrenal medulla are regarded as?
modified sympathetic postganglionic neurons
76
What are the characteristics of catecholemines?
- secreted in response to intense emotional reactions
- increase heart rate
- dilates blood vessels to cardiac and skeletal m
- bronchiole dilation
- vasoconstriction of blood to GI tract, kidneys, skin
77
What is pheochromocytoma?
benign tumor of the chromaffin cells
78
What are the symptoms of pheochromocytoma?
elevated heart rate
elevated bp
palpitations
diaphoresis
anxiety
headaches
nausea
79
What percent of pheochromocytoma are familial?
25%
