Biochem & Phys Flashcards
1
Q
What is the principal regulator of adrenomedullary secretion of catecholamines?
A
ACh release from preganglionic sympathetic fibers of the splanchnic nerves
2
Q
somatic innervation of the penis (both motor & sensory)
A
pudendal nerve (S2-S4)
3
Q
nerve plexuses that supply sympathetic motor fibers (5) to the male sex organs
A
- celiac (this is a “pass through)
- superior mesenteric
- inferior mesenteric
- superior hypogastric
- inferior hypogastric or pelvic (receives sympathetic supply from hypogastric nerve)
4
Q
where does the spermatic ganglion receive sympathetic fibers?
A
lumbar sympathetic nerves & other ganglia
5
Q
prolonged meiosis arrest in prophase I
A
dictyotene stage
These are primary oocytes.
6
Q
primary oocyte with a surrounding single layer of pregranulosa cells
A
primordial follicle
7
Q
larger oocyte surrounded by a single layer of cuboidal granulosa cells
A
primary follicle
8
Q
Primary oocyte surrounded by several layers of cuboidal granulosa cells. Formation of capillaries and increased vascular supply to developing follicular units is also present.
A
secondary follicle
9
Q
from stromal cells that differentiate and surround the follicle
A
theca cells
10
Q
Which cells secrete fluid into the antrum?
A
granulosa cells
11
Q
stage of follicular development when the antrum is present
A
tertiary follicle
The second antral stage is preovulatory: Graafian follicle
12
Q
mucopolysaccharides immediately surrounding the oocyte
A
zona pellucida
13
Q
most metabolically active follicular cells which are farthest from the center of the follicle and contain large quantities of LH receptors
A
mural granulosa cells
14
Q
Cells that become the large luteal cells of the corpus luteum
A
antral granulosa cells
15
Q
What regulates the concentration of SHBG?
A
Estrogen increases it. Testosterone decreases it. Women have twice as much SHBG as men.
16
Q
Estrogen is metabolized to what less active steroids by the liver?
A
Estriol and estrone
17
Q
How does the ovary synthesize estrogen?
A
LH stimulates the theca cells to synthesize androgens which diffuse to granulosa cells that synthesize estrogen under the stimulation of FSH. Granulosa cells contain aromatase. Theca cells have CYP17 activity.
18
Q
What inhibits milk production during pregnancy?
A
High levels of progesterone
19
Q
Why is hormone secretion pulsatile?
A
Prevent downregulation of the receptor
20
Q
Serum proteins that bind thyroxine
A
Thyroxine binding globulin
Transthyretin
21
Q
Why is the level of cortisol highest in the morning?
A
to prepare you to get up
it’s lowest in the evening.
22
Q
Main regulator of ADH release
A
increased plasma osmolality (mainly hypernatremia) and decreased blood volume (hypovolemia)
23
Q
Neurons that synthesize and release ADH and oxytocin
A
magnacellular neurons of the PVN & SON (supraoptic nuclei)
24
Q
Causes central diabetes insipidus
A
decreased release of ADH
25
Causes nephrogenic diabetes insipidus
decreased renal responsiveness to ADH -> mutation of V2R and/or AQP2
26
SIADH manifestations
1. central edema or coma from decreased plasma osmolality causing intracellular fluid shift
2. increased expression of AQP2 causing water retention & hyponatremia (Na 125-135)
3. increased GFR from increased water retention therefore more sodium excretion
27
symptoms associated with sodium 125-135
nausea, loss of appetite, fatigue, headache
28
symptoms associated with sodium < 120
weakness, confusion, sleepiness, vomiting
29
second messenger for insulin, GH and IGF1, prolactin & insulin receptors
tyrosine kinase
| these receptors are dimers
30
hormone and binding protein complex formation serves what functions?
- provides a reservoir poor of hormone minimizing fluctuations in concentration
- extends the half-life of the hormone
31
effects of increased synthesis of T4 binding globulin in pregnancy
- increases level of TSH secretion
| - increases plasma T4 (not free!)
32
amine hormones (derivatives of tyrosine)
epinephrine
norepinephrine
dopamine
thyroid hormones
33
positive feedback loop of estrogen
During the follicular phase of the menstrual cycle, estrogen released by the ovaries acts on the anterior pituitary to rapidly release a burst of LH and FSH. FSH and LH burst causes ovulation and release of more estrogen.
34
positive feedback of oxytocin
Dilation of the cervix causes release of oxytocin by the posterior pituitary. Oxytocin stimulates uterine contractions, causing further dilation of the cervix.
35
hormone concentration that causes 50% of maximal response
sensitivity
36
methods of downregulation of receptors
decrease numbers
| decrease affinity for hormone
37
Which subunit of G proteins binds to GDP or GTP
alpha
G proteins have alpha, beta and gamma subunits
binding to GTP makes it "active"
38
Hormones that utilize cAMP second messenger (12)
1. ACTH
2. LH
3. FSH
4. TSH
5. ADH (V2)
6. hCG
7. MSH
8. CRH
9. calcitonin
10. PTH
11. Glucagon
12. beta receptors (beta1 & beta2)
39
Hormones that use phospholipase C second messenger (7)
1. GnRH
2. TRH
3. GHRH
4. ANG II
5. ADH (V1)
6. Oxytocin
7. alpha1 receptors
40
type of hormone receptor that uses Janus kinase downstream messengers
GH
| activation of STAT (signal transducers and activators of transcription) causes synthesis of proteins
41
Connects the hypothalamus to the pituitary gland
infundibulum
42
hypothalamic nuclei that synthesize ADH
supraoptic nuclei (SON)
43
hypothalamic nuclei that synthesize oxytocin
paraventricular (PVN)
44
supply most of the blood to the anterior pituitary
portal blood vessels
| Most of the blood supply to the anterior pituitary is venous
45
hormones that have same alpha subunits but different beta subunits
hCG, LH, FSH, and TSH
46
preprohormone for ACTH and MSH
POMC = preproopiomelanocortin
47
anterior pituitary cells that synthesize GH
somatotrophs
48
hormones that share 75% and 80% homology with GH, respectively
prolactin and human placental lactogen
49
potent stimuli for GH secretion
starvation
hypoglycemia
Other: exercise, fever, trauma, anesthesia, stage III & IV sleep
50
When is GH secretion rate the highest?
puberty
51
Inhibit GH secretion
obesity, hyperglycemia, increased FA concentration, senescence, SOMATOSTATIN, GH, beta agonists, pregnancy
52
somatomedin C
IGF-1
| The growth-promoting effects of GH are mediated mostly through production of IGF-1. IGF-1 is produced in the liver.
53
Effects of GH
```
insulin resistance (hyperglycemia)
lipolysis
increased protein synthesis (increased lean muscle mass & increased organ size)
increased linear growth
cartilage metabolism -> growth
```
54
Postpubertal signs of excess GH
```
increased periosteal bone growth
increased organ size
increased hand and foot size
tongue enlargement
coarse facial features
insulin resistance
glucose intolerance
```
55
treatment for GH excess
somatostatin analogs (octreotide)
56
most common cause of excess GH
pituitary adenoma
57
Which hormone is tonically inhibited by dopamine?
prolactin
Anything that interrupts the connections between the hypothalamus & the pituitary (disrupts the infundibulum) and halts the inhibitory action of dopamine causes milk production (galactorrhea).
**Prolactin is the ONLY pituitary hormone that is tonically inhibited!
58
treatment for excess prolactin
bromocriptine (dopamine agonist)
59
How does prolactin inhibit ovulation?
inhibition of release of GnRH -> causes infertility
60
Inhibit ADH release
ethanol, ANP, alpha agonists
61
stimulate ADH secretion
pain, nausea, hypoglycemia, nicotine, opiates, antineoplastic drugs
62
location of V2 receptor
principal cells of the distal tubule and collecting ducts
63
location of V1 receptor
vascular smooth muscle
64
low ADH, large volumes of dilute urine, concentrated plasma -> due to failure of the posterior pituitary to secrete ADH
central diabetes insipidus
65
principal cells are unresponsive to ADH due to defect in the V2 receptor; excretion of large volumes of dilute urine, increased serum osmolality; increased ADH level from increased serum osmolality
nephrogenic diabetes insipidus
| tx: thiazide diuretic
66
excess ADH secretion from an ectopic site (small cell carcinoma of the lung), dilute serum; concentrated urine
SIADH
| Tx: demeclocycline (ADH antagonist) & water restriction
67
produces milk ejection
oxytocin
| in addition to stimulation by suckling, oxytocin is secreted in response to cervical dilation and orgasm
68
responsible for I- into the follicular cell via the Na/I cotransporter
Na EC gradient
69
oxidizes I- to I2
thyroid peroxidase
70
blocks synthesis of thyroid hormones by inhibiting thyroid peroxidase
propylthiouracil (PTU)
71
releases DIT and MIT from thyroglobulin
lysosomal enzymes
72
enzyme that converts T4 to T3 in the target tissues
5' iodinase
starvation inhibits this enzyme in skeletal muscle, lowering O2 consumption and BMR during times of decreased caloric intake
73
hypothalmic nucleus that secretes TRH
PVN
74
actions of TSH
regulate growth of the thyroid gland
| secretion of thyroid hormones
75
Why is the thyroid gland enlarged in Graves disease?
IgG to TSH receptor causes activation, producing the same response as if TSH is bound: thyroid hormone synthesis & release plus hyperplasia/hypertrophy
76
mechanism of action of thyroid hormones
growth, bone maturation, increased activity of Na/K ATPase, increase O2 consumption, increased heat production, increased BMR, increased glucose absorption, glycogenolysis, gluconeogenesis, lipolysis, protein synthesis, CO
77
Why are beta blockers effective treatment for thyrotoxicosis?
thyroid hormone causes increased expression of beta receptors in heart (beta1), skeletal muscle & adipose, making them more sensitive to sympathetic stimulation
78
accumulation of osmotically active mucopolysaccharides in the interstitial fluid, seen in hypothyroidism
myxedema
79
decreased thyroid hormone synthesis due to antibodies to peroxidase; goiter present due to increased TSH from lack of negative feedback from hormones.
autoimmune thyroiditis
80
Anti-inflammatory effects of cortisol
- induces synthesis of lipocortin which inhibits phospholipase A2
- inhibits IL-2 and T cell proliferation
- inhibits release of histamine & serotonin from mast cells & platelets
* note inhibition of IL-2 and T cells also serves immunosuppressive role
81
How does cortisol maintain vascular responsiveness to catecholamines?
upregulation of alpha1 receptors (increased synthesis)
82
How does cortisol inhibit bone formation?
- decreases synthesis of type I collagen (main component of matrix)
- decreases osteoblast activity
- decreases GI calcium absorption
83
What are the expected physiologic changes to aldosterone deficiency (ie adrenal insuff)?
- decreased sodium absorption
- decreased K+ and H+ secretion
- ECF volume contraction
- hypotension
- hyperkalemia
- metabolic acidosis
84
What enzyme converts cortisol to cortisone?
11 beta HSD
85
What is the difference between Cushing syndrome and Cushing diease?
Cushing disease is caused by hypersecretion of ACTH from a pituitary adenoma, driving the adrenal cortex to produce excess cortisol. Cushing syndrome is from chronic excess of corticosteroids.
Disease: increased ACTH
Syndrome: decreased ACTH from neg feedback
86
Why does HTN occur with Cushing disease?
cortisol is a weak mineralocorticoid and it also upregulates alpha 1 receptors
87
primary hyperaldosteronism caused by aldosterone-secreting tumor; see increased sodium, volume expansion, increased potassium secretion (metabolic alkalosis) and HTN
Conn syndrome
88
Destruction of all layers of the adrenal cortex
Addison disease
89
In a female fetus: causes masculinization of the external genitalia, penis-like clitoris, and scrotum-like labia. In childhood the excess androgens increase linear growth, cause precocious puberty and suppress gonadal function
21 beta hydroxylase deficiency
* low cortisol production results in increased ACTH and cause a trophic effect on the adrenal cortex: congenital adrenal hyperplasia
90
absence of cortisol and adrenal adrogens, shunting steroid synthesis toward mineralocorticoid synthesis; Results in HTN, hypokalemia, metabolic alkalosis
17 alpha hydroxylase deficiency
Note: aldosterone is actually low in this syndrome because of the increase in 11-DOC and corticosterone, both of which have MR activity. HTN decreases renin release therefore aldosterone release.
91
negative feedback for GnRH and LH is by what?
estrogen
92
negative feedback for FSH is by what?
inhibin
93
In menopause, do LH & FSH increase or decrease?
Increase due to loss of feedback inhibition by estrogen since estrogen is decreased.
94
ethicities prone to type 1 DM
```
African American
Latino
Native American
Asian American
Pacific Islander
```
95
childhood virus associated with increased incidence of IDDM
Rubella
96
short-acting insulin dosing should be based on what?
carbohydrate intake of meals and snacks
97
oral glucose load given and GH measured. Normal is GH < 1 ng/mL
test for acromegaly
IGF-1 produces negative feedback to prevent pituitary release of GH. This inhibition of GH release is mediated by release of somatostatin. Remember: glucose inhibits GH release. Hypoglycemia stimulates GH release!
98
To what tissue does IGF1 bind?
Skeletal muscle
99
Why is galactorrhea present with acromegaly?
GH can interact with the PRL receptor
