12 - Endocrine Flashcards
1
Q
What is a hormone?
A
- chemical released by a cell in 1 part of the body that affects cells in another
- secreted & travel a distance
2
Q
Types of hormones?
endocrine, neuroendocrine, exocrine
A
- Endocrine - hormones are secreted directly into the bloodstream
- Neuroendocrine - hormones produced by neurons secreted into the bloodstream
- Exocrine - hormones are secreted directly into a duct (can enter bloodstream)
3
Q
Autocrine vs. Paracrine
A
- Autocrine - chemicals that exert effects on the same cells
- Paracrine - locally acting chemicals that affect nearby cells
4
Q
Hormones alter target cell activity by which 2 mechanisms?
A
- Second messengers - regulatory G proteins tend to be amino-acid based hormones
- Direct gene activation - tend to be steroid hormones
5
Q
What is Up-regulation?
A
- target cells form more receptors in response to the hormone
6
Q
What is down-regulation?
A
- target cells lose receptors in response to the hormone
7
Q
What is Permissiveness?
A
- 1 hormone cannot exert its effects w/out another hormone being present
- (ex. Thyroid hormone increases epinephrine receptors; cortisol allows growth hormone to work in cells)
8
Q
What is Synergism?
A
- more than 1 hormone produces the same effects on a target cell
- (insulin & glucagon-like-peptide-1)
9
Q
What is Antagonism?
A
- 1 or more hormones opposes the action of another hormone
- (insulin & glucagon; dopamine & prolactin)
10
Q
How does a Humoral Stimuli cause hormone release?
A
- Secretion of hormones in direct response to changing blood levels of ions & nutrients
- Ca2+ low (regulator) -> thyroid gland -> increase PTH -> Ca2+
11
Q
How does a Neural stimuli cause hormone release?
A
- Nerve fibers stimulate hormone release
- Ex. Innervates adrenal gland -> release NE & E
12
Q
How does a Hormonal stimuli cause hormone release?
A
- Release of hormones in response to hormones produced by other endocrine organs
- Tropic hormone - hormone that alter the secretion of other hormone(s)
- Ex. Hormones from pituitary -> stimulate hormone release from thyroid, adrenal & gonad
13
Q
What are Eicosanoids?
A
- short-lived (secs to mins) biologically active lipids w/ autocrine & paracrine activity
- not a true hormone
Ex. leukotrienes & prostaglandins
14
Q
What are 2 amino acid based hormone mechanisms
A
- cAMP second messenger
- PIP2 mechanism
14
Q
What are the Eicosanoid precursors and Pathways?
A
- membrane phospholipids -> Phospholipase A2 converts it to -> arachidonic acid -> Cox (prostaglandins) & Lox (leukotrienes)
15
Q
What is the steroid hormone mechanism?
A
- steroid hormone binds receptor-chaperone complex -> release chaperones -> steroid-hormone complex binds chromatin -> gene transcription & translation
- act on multiple gene targets NOT just 1 gene
16
Q
T or F: All steroid hormones have to act through gene expression
A
- FALSE
- Ex. estrogen receptor -> leads to generalized transdution kinda like G-protein coupled receptors
17
Q
What is Herceptin
A
- antibody treatment of women w/ HER2+ metastatic breast cancer
- bind HER2 receptors -> decrease signalling
18
Q
What is the Pituitary gland?
A
- neurohypophysis - posterior lobe (neural tissue), release hormones from the hypothalamus
- adenhypophysis - anterior lobe (glandular tissue), synthesizes & secretes a number of hormones
19
Q
What are the hormones secreted by the Adenohypophysis
A
- tropic hormones - TSH, ACTH, FSH, LH, GH
- other - Prolactin, B-lipotropin, Melanoyte stimulating hormone (MSH)
20
Q
What is GH?
A
- growth hormone
- anabolic - tissue building
- acts on liver, bone & skeletal muscle
- mediated by somatotropins (IGFs)
21
Q
What is TSH?
A
- thyroid stimulating hormone
- stimulated thyroid to release thyroid hormones (T4 & T3)
22
Q
What is ACTH?
A
- Adrenocorticotropic hormone
- internal & external stressors (fever, hyperglycemia & stressors) trigger release of CRH -> release of ACTH -> cortisol, NE & E
23
Q
What are gonadotropins?
A
- LH & FSH
- regulate function of ovaries & testes
- FSH - stimulates gamete production
- LH - promotes testosterone & estrogen & progesterone production
24
Q
What is prolactin?
A
- stimulated milk production by the breasts
- triggered by PRH & inhibited by PIH (dopamine)
- suckling stimulated PRH release
25
Q
What hormones are released by Neurohypophysis?
A
- oxytocin & ADH
26
Q
What is oxytocin?
A
- regulated by positive feedback mechanism
- increased intensity of uterine contractions during birth, milk letdown, sexual arousal & satisfaction
27
Q
What is ADH?
A
- plasma osmolarity monitored by osmoreceptors in hypothalamus triggers release
- high solutes -> ADH released -> preserving water
- large decreases in blood volume/pressure can trigger release
28
Q
What is the Thyroid Gland?
A
- 2 lateral lobes connected by the isthmus
- follicle cells - produce thyroglobulin (precursor to thyroid hormone)
- colloid - fill lumen of follicles
29
Q
What does Thyroid Hormone work on?
A
- USTAT
- uterus, spleen, testis, adult brain, thyroid gland
30
Q
What is the more active form of Thyroid Hormone?
A
- T3 - 2 tyrosine + 3 iodine
31
Q
What are the steps in the synthesis of TH?
A
- thyroglobulin synthesized & discharged into follicle lumen
- iodide is trapped
- iodide is oxidized to iodine
- iodine is attached to tyrosine in colloid
- iodinated tyrosines are linked together to form T3 & T4
- thyroglobulin colloid is endocytosed & combined w/ a lysosome
- lysosomal enzymes cleave T4 & T3 from thyroglobulin colloid & hormones diffuse into bloodstream
32
Q
What is Calcitonin?
A
- produced by the parafollicular cells or C-cells
- calcitonin lower blood Ca2+
- inhibits osteoclast activity
- stimulates Ca2+ incorporation into bone matrix
33
Q
What is Parathyroid hormone?
A
- PTH regulates Ca2+ in blood
- counteracts calcitonin
- increases ca2+ - stimulates osteoclasts, enhances reabsorption of Ca 2+ & secretion of phosphate by kidneys
- promotes vitamin D activation to calcitriol which increases Ca 2+ absorption of the intestine
- rising Ca2+ in blood inhibits PTH release
34
Q
What are the adrenal glands & what hormones do they release?
A
- paired, pyramid-shaped organs atop the kidneys
- adrenal medulla - part of SNS -> NE & E release
- adrenal cortex - releases steroid hormones called corticosteroids
35
Q
What hormones do the different layers of the adrenal cortex release?
A
- zona glomerulosa - mineralocorticoids (aldosterone)
- zona fasciculata - glucocorticoids (cortisol)
- zona reticularis - gonadocorticoids (androgens)
36
Q
What 4 things regulate Aldosterone?
A
- renin-angiotensin mechanism
- increased plasma K+ (Na+)
- ACTH
- Atrial natriuretic peptide (ANP) - negative regulator
37
Q
What is Aldosterone?
A
- mineralocorticoid
- maintains Na+ by reducing excretion of Na+ from body
- stimulates reabsorption of Na+ by kidneys
38
Q
What is cortisol?
A
- help resist the body resist stress
- keeps blood sugar constant & maintains blood volume
- provokes - glucogenesis (formation of glucose) & rises in blood glucose, fatty acids & AAs
39
Q
What is Testosterone?
A
- gonadotropin -> androgen
- contributes to onset of puberty, appearance of secondary sex characteristics, sex drive in females
40
Q
Short term stress response & adrenal medulla
A
- release of catecholamines ( epinephrine & norepinephrine)
- increased heart rate
- increased blood pressure
- glycogen -> glucose
- dilation of bronchioles
- changes blood flow - decreased digestive system & reduced urine output
- increased metabolic rate
41
Q
Long term stress response & adrenal cortex
A
- release ACTH -> adrenal cortex -> mineralcorticoids & glucocorticoids
- retention of Na+ & water by kidneys & increased blood volume & pressure
- proteins & fats converted to glucose, increased blood glucose, suppression of immune system
42
Q
What hormones are produced by the pancreas
A
- insulin - decreases blood sugar
- glucagon - increases blood sugar
43
Q
What hormone does the Pineal gland produce?
A
- melatonin
44
Q
What hormones are produced by the Thymus?
A
- thymopoietin & thymosins
