Intro to Endocrinology Flashcards
1
Q
5 primary hormones from hypothalamus
A
TRH CRH GnRH Somatostatin Dopamine
2
Q
7 hormones of anterior pituitary gland
A
TSH FSH LH ACTH MSH Growth hormone Prolactin
3
Q
2 hormones of posterior pituitary
A
ADH
Oxytocin
4
Q
2-3 hormones from thyroid gland
A
T3, T4
Calcitonin
5
Q
What gland releases PTH
A
Parathyroid gland
6
Q
2 hormones from pancreas
A
Insulin
Glucagon
7
Q
2 hormones from adrenal medulla
A
Norepinephrine
Epinephrine
8
Q
2 hormones from kidney
A
Renin
1,25 dihydroxycholecalciferol
9
Q
3 hormoens from adrenal cortex
A
Cortisol
Aldosterone
Adrenal androgens
10
Q
Hormones from testes vs. ovaries
A
Testes = testosterone
Ovaries = estradiol, progesterone
11
Q
2 hormones from corpus luteum
A
Estradiol
Progesterone
12
Q
4 hormones from placenta
A
hCG
Estriol
Progesterone
hPL
13
Q
3 general classes of hormones
A
Proteins + peptides
Amines
Steroids
14
Q
Protein and peptide hormones are stored in ____ ____ until needed
Polypeptides with > 100 aa are considered _____
Polypeptides with <100 aa are considered _____
They are _____-soluble
A
Secretory vesicles
Proteins
Peptides
Water
15
Q
Amine hormones are derived from _____
A
Tyrosine
16
Q
Steroid hormones are synthesized from ______, they are ______-soluble and they are not stored
A
Cholesterol; lipid
17
Q
Describe general synthesis of protein and peptide hormones
A
Usually synthesized as larger polypeptides, starting as a preprohormone (not biologically active)
Signal peptide is removed in ER to produce prohormone
Once packed into vesicles in golgi, they are cleaved by proteolytic enzymes generating the active form
18
Q
Protein and peptide hormones are stored in secretory vesicles until endocrine cell is stimulated.
What are some possible stimuli for exocytosis?
A
Increased IC calcium d/t membrane depolarization
Activation of GPCR, followed by increased cAMP and activation of PKA
19
Q
What are some glands that secrete steroid hormones?
A
Adrenal cortex
Gonads
Corpus luteum
20
Q
What are some modifications that can be made to cholesterol molecules to change their hormone identity?
A
Removal or addition of side chains
Hydroxylation of steroid nucleus
Aromatization of steroid nucleus
21
Q
What are the 2 possible sources of cholesterol?
A
About 80% is taken up as LDL particles through receptor-mediated endocytosis
The rest is de novo synthesis from acetyl coA
22
Q
What is the difference between genomic and nongenomic actions of steroid hormones?
A
Genomic = modulate transcription by interaction with intracellular nuclear receptors
Nongenomic = rapid steroid action via specific receptor-mediated actions or direct steroid membrane interactions
23
Q
Amine hormones are derived from tyrosine. What are the 2 groups of amine hormones?
A
Catecholamines
Thyroid hormones
24
Q
Catecholamines are amine hormones synthesized in the _____ and secretory granules. They act through ________ associated receptors
A
Cytosol; cell-membrane
25
Thyroid hormones are synthesized by the thyroid gland and stored as ____ in glandular follicles
They cross the cell membrane and act through ____ receptors
Thyroglobulin
Nuclear
26
Which of the following has a faster metabolic clearance from the body, and thus a shorter half life:
Thyroxine vs. triiodothyronine
Triiodothyronine
27
Which of the following has a faster metabolic clearance from the body, and thus a shorter half life:
Cortisol
Testosterone
Aldosterone
Aldosterone > testosterone > cortisol
28
Which of the following has a faster metabolic clearance from the body, and thus a shorter half life:
Thyrotropin
Insulin
ADH
Insulin > ADH > thyrotropin
29
Peptide hormone from hypothalamus that stimulates secretion of TSH and prolactin
TRH
30
Peptide hormone from hypothalamus that stimulates secretion of ACTH
CRH
31
Peptide hormone from hypothalamus that stimulates secretion of LH and FSH
GnRH
32
Peptide hormone from hypothalamus that inhibits secretion of growth hormone
SRIF (aka somatostatin)
33
Peptide hormone from hypothalamus that stimulates secretion of growth hormone
GHRH
34
Amine hormone from hypothalamus that inhibits secretion of prolactin
Dopamine (aka PIF)
35
Peptide hormone from anterior pituitary that stimulates synthesis and secretion of thyroid hormone
TSH
36
Peptide hormone from anterior pituitary that stimulates sperm maturation in sertoli cells of testes OR follicular development and estrogen synthesis in ovaries
FSH
37
Peptide hormone from anterior pituitary that stimulates testosterone synthesis in Leydig cells of testis OR ovulation, formation of corpus luteum, estrogen, and progesterone synthesis in ovaries
LH
38
Peptide hormone from anterior pituitary that stimulates protein synthesis and overall growth
GH
39
Peptide hormone from anterior pituitary that stimulates milk production and secretion in breast
Prolactin
40
Peptide hormone from anterior pituitary that stimulates synthesis and secretion of adrenal cortical hormones like cortisol, androgens, and aldosterone
ACTH
41
Peptide hormone from anterior pituitary that stimulates melanin synthesis
MSH
42
Peptide hormone from posterior pituitary that stimulates milk ejection from breasts and uterine contractions
Oxytocin
43
Peptide hormone from posterior pituitary that stimulates water reabsorption in principal cells of collecting ducts and constriction of arterioles
ADH (vasopressin)
44
Amine hormone from thyroid that stimulates skeletal growth, oxygen consumption, heat production, protein, fat, and carb utilization, and perinatal maturation of the CNS
T3 and T4
45
Peptide hormone from thyroid that decreases serum Ca
Calcitonin
46
Peptide hormone from parathyroid gland that increases serum Ca
PTH
47
Steroid hormone from adrenal cortex that stimulates gluconeogenesis, inhibits inflammatory reposnes, suppresses immune responses, enhances vascular responsiveness to catecholamines
Cortisol (glucocorticoid)
48
Steroid hormone from adrenal cortex that increases renal Na reabsorption, K secretion, and H secretion
Aldosterone (mineralocorticoid)
49
Steroid hormone from testes that stimulates spermatogenesis, stimulates male secondary characteristics
Testosterone
50
Steroid hormone from ovaries that stimulates growth and development of female repro system, follicular phase of menstrual cycle, development of breasts, prolactin secretion, and maintains pregnancy
Estradiol
51
Steroid hormone from ovaries that stimulates luteal phase of menstrual cycle and maintains pregnancy
Progesterone
52
Peptide hormone from placenta that stimulates estrogen and progesterone synthesis in corpus luteum of early pregnancy
HcG
53
Peptide hormone from placenta that has growth hormone-like and prolactin like actions during pregnancy
Human placental lactogen (HPL) aka human chorionic somatomammotropin
54
Peptide hormone from pancreas that decreases blood glucose
Insulin (beta cells)
55
Peptide hormone from pancreas that increases blood glucose
Glucagon (alpha cells)
56
Steroid hormone from kidney that increases intestinal Ca absorption and bone mineralization
1,25 dihydroxycholecalciferol
57
Peptide hormone from kidney that catalyzes conversion of angiotensin to angiotensin I
Renin
58
What are 2 general mechanisms to turn secretion of hormones on vs. off? Which way is most common?
Neural mechanism (ex.:sympathetic preganglionic innervation of adrenal medulla - when stimulated causes release of catecholamines into circulation)
Feedback mechanism = more common! typically negative feedback mechanisms
59
T/F: Positive feedback mechanisms are rare, self augmenting, and rarely used to maintain homeostatic functions
True
60
Positive feedback mechanisms are rare, self augmenting, and rarely used to maintain homeostatic functions. What are some examples?
Menstrual cycle - increasing estrogen levels in blood temporarily stimulate FSH and LH release from anterior pituitary, further increasing estrogen levels and eventually leading to ovulation
Delivery of a fetus - oxytocin stimulates and enhances labor contractions
61
Negative feedback underlies homeostatic regulation of organ systems. What is the difference between long-loop, short-loop, and ultra-short-loop negative feedback mechanisms?
Long-loop = hormone released from 3rd tier (peripheral gland) feeds back all the way to first and second tier
Short-loop = hormone secreted from second tier feeds back to 1st tier (ex: anterior pituitary feeds back to hypothalamus)
Ultrashort loop = gland inhibits its own secretion
62
Most of the endocrine system is organized into axes, what are 3 examples?
Hypothalamus - Pituitary - Adrenal = HPA axis
Hypothalamus - Pituitary - Thyroid = HPT axis
Hypothalamus - Pituitary - Gonads = HPG axis
63
In what type of feedback loop is secretion of a hormone stimulated or inhibited by a change in the level of a specific extracellular signal?
Physiological response driven negative feedback loop
[increase in BG concentration stimulates insulin secretion; decrease in BG inhibits insulin secretion]
64
The first tier of the endocrine axes is highly regulated by ______ inputs
Neural
65
The first tier of the endocrine axes (hypothalamus) is highly regulated by neural inputs. What are the 2 major inputs?
Suprachiasmatic nucleus (SCN) - imposes circadian rhythm on secretion of hypothalamic releasing hormoens and endocrine axes
Pineal gland - releases melatonin which feeds back to SCN info about day/night
[physiological stress also influences release of hormoens from hypothalamus]
66
SCN neurons represent an internal circadian clock
When light hits the eyes, a signal is sent to the ________, as well as the SCN via the _______ tract
From there, the SCN signals the hypothalamus, as well as the pineal gland which secretes ______, regulating day/night coordinated rhythms via endocrine, metabolic, and behavioral factors
Lateral geniculate nucleus; retinohypothalamic tract
Melatonin
67
Circadian rhythms regulate multiple hormone functions in the body.
What changes occur just after midnight in body temperature, systolic BP, plasma growth hormone, plasma melatonin, and plasma ACTH
Body temp decreases
Systolic BP decreases
Plasma GH spikes
Plasma melatonin spikes
Plasma ACTH gradually decreases until 12am then it increases until 8 am
68
Key aspects in regulation of circulating levels of hormones:
Receptors confer _____ to hormone actions, in that they form a hormone-receptor complex
Responsiveness of target tissue to a hormone is expressed in the dose-response relationship. ______ = hormone concentration that produces 50% of the maximal response.
Specificity
Sensitivity
69
What are 2 ways that receptor responsiveness to hormone can change?
Changing the # of receptors
Changing the affinity of the receptors for the hormone
70
Up-regulation = increase receptor number or sensitivity of target tissue when hormone levels are low. What are the methods of upregulation?
Increase in synthesis of new receptors
Decrease in degradation of existing receptors
Activating receptors
71
Downregulation = reduce receptor number or sensitivity of target tissue when hormone levels are high for an extended period of time. What are the methods of downregulation?
Decrease in the synthesiss of new receptors
Increase in degradation of existing receptors
Inactivating/desensitizing receptors
72
3 major mechanisms of hormone action on target cells
Adenylyl cyclase mechanism (hormone —> adenylyl cyclase —> cAMP —> PKA)
Phospholipase C mechanism (hormone —> PLC —> IP3/DAG/Ca++ —> PKC/calmodulin)
Steroid hormone mechanism (hormone —> cytosolic or nuclear receptor)
73
Which of the following mechanisms is utilized by GnRH, TRH, GHRH, and oxytocin?
A. Adenylyl cyclase mechanism
B. Phospholipase C mechanism
C. Steroid hormone mechanism
B. Phospholipase C mechanism
74
Which of the following mechanisms is utilized by thyroid hormones, glucocorticoids, aldosterone, estrogen, and testosterone?
A. Adenylyl cyclase mechanism
B. Phospholipase C mechanism
C. Steroid hormone mechanism
C. Steroid hormone mechanism
75
Which of the following mechanisms is utilized by ACTH, LH, FSH, TSH, and glucagon?
A. Adenylyl cyclase mechanism
B. Phospholipase C mechanism
C. Steroid hormone mechanism
A. Adenylyl cyclase mechanism
76
What is the guanylyl cyclase MOA?
1st messenger = hormone such as ANP, NO
—ANP acts through receptor with GC activity
—NO diffuses to cytosol and activates cytosolic GC
Primary effector = guanylate cyclase
2nd messenger = cGMP
Secondary effector = PKG
77
Tyrosine kinases fall into what 2 major categories?
Receptor tyrosine kinases = have intrinsic TK activity within receptor molecule, when activated they autophosphorylate themselves and other proteins
Tyrosine kinase-associated receptors = associate noncovalently with proteins that have tyrosine kinase activity (e.g. JAK)
78
Insulin, IGF-1, growth hormone, and prolactin have what hormone-receptor MOA?
```
A. Adenylyl cyclase mechanism
B. PLC mechanism
C. Steroid hormone mechanism
D. Tyrosine kinase mechanism
E. Guanylate cyclase mechanism
```
D. Tyrosine kinase mechanism
79
Examples of endocrine dysfunction/dysregulation/changes include hypofunction, hyperfunction, and mass lesions.
Mass lesions are characterized by enlargement of the endocrine organ due to an underlying ____ or ____
Neoplasia; hyperplasia
80
Examples of endocrine hyperfunction
Neoplastic (benign pituitary adenomas, malignant adrenal cancer, ectopic SIADH)
Autoimmune (graves disease)
Iatrogenic (cushings syndrome, hypoglycemia)
Infectious/inflammatory (subacute thyroiditis)
Activating receptor mutations (TSH receptor)
81
Examples of endocrine hypofunction
Hemorrhage/infarction (sheehans, adrenal insufficiency)
Nutritional deficiency (vitamin D, iodine)
Enzyme defects (21 hydroxylase def)
Autoimmune (addisons disease, hashimotos thyroiditis, type I DM)
Iatrogenic (hypothyroidism, surgical, radiation induced hypopituitarism)
Infectious/inflammatory (adrenal insufficiency)
Hormone mutations (GH, AVP)
