Endocrine Flashcards
Hypothalamus coordinates component of ________ and _________
endocrine and behavior
3 things the hypothalamus is critical for
- metabolism
- reproduction
- growth
Endocrine (3)
- secreting internally (most commonly into systemic circulation)
- internal or hormonal secretion of a ductless gland
- denoting a gland
What is a hormone?
chemical substance produced by specialized glands or tissue
What is the root of hormone?
- Greek
- to excite/ arouse
- to set in motion
How is a hormone transported?
by the blood
T/F: Hormones bathe all cells
true
What “acts on distant target organs at low concentrations”?
hormone
How do targets receive the hormone?
targets have receptors that mediate the response
Intracrine hormone
WITHIN one cell
Autocrine hormone
released by cell and used on receptor of that cel
Paracrine hormone
local hormone
Endocrine hormone
genuine hormone
Neuroendocrine hormone
neurohormone
4 broad groupings of hormones
- repro/sexual differentiation
- development and growth
- homeostasis
- regulations of metabolism and nutrient supply
T/F: A single hormone may have one or more functions
True
T/F: A single function may be controlled by more than one hormone
True
The autonomic reflex loops intergrate what 2 things?
ANS and endocrine system
Examples of stress-related regulatory behaviors
- pacing
- licking
- excess groomin
- masturbation in primates
4 Major Types of Hormones
- proteins
- peptides
- amines
- steroids
_________ are synthesized as preprohormones and modified to prohormones
Protein hormones
Approx. _____ % of the hormones are protein.
85%
Are the actions of protein hormones fast or slow?
relatively fast
Why can proteins NOT be administered orally?
easily digested and inactivated by GI enzymes
What portion of the cell cytoplasm does protein synthesis?
ribosome
Approx. ____% of the hormones are steroids
15%
What are steroid hormones derived from? Where are they made?
cholesterol; liver
Steroid hormones can alter _________ synthesis
protein
Steroids have relatively ________ actions than peptides, but are __________ acting
slower; longer
What type of hormones are hydrophilic and dissolve in plasma?
proteins/peptides
These types of hormones are lipophilic and thus need carrier proteins to be transported in the blood.
steroid and thyroid hormones
Can more of the steroid and thyroid hormones be found free or bound to protein in the blood?
bound to protein
Secondary messenger systems are related to what kind of hormones?
protein
What type of hormone can affect mRNA synthesis?
steroid
What is the purpose of the steroid hormone conjugation with sulfates and glucoronoids?
increases water solubility
Exogenous hormones may be influenced by… (6)
- tissue type
- time of observation
- species, sex, age
- type of hormone, formulation how and where delivered
- pattern of release or time of day (circadian rhythm)
- dose-effect relationship/ limit of endocrine regulation
Why are disturbances in feedback loops clinically important?
Significance in diagnosis is pivotal
Factors for hormone release
- sleep
- circadian rhythms (24 hr cycles)
- Diurnal rhythms (during day vs night)
- Daylength = esp. for seasonal breeders
- nutritional state
- ultradian rhytms (cycles more freq. than 24 hrs)
- exercise = strenous exercise can stimulate GH
Where is the timing mechanism?
in the superchasmatic nucleus
What does it mean if a disorder is iatrogenic?
brought on by physician’s treatment
How is the hypothalamus KEY for regulating homeostasis?
coordination of behavior (Somatic Nervous System), ANS, and endocrine system
This system’s response is quicker and in a more localized fashion.
What is the nervous system?
This system’s response bathes all cells w/ hormone and may take minutes, days, or months to see actions of hormones.
What is the endocrine system?
These two neurohormones are produced in the posterior pituitary
oxytocin and vasopressin
Another name for the post. pit.?
neurohypophysis
6 hormones produced by the hypothalamus that control the ant. pit.
- corticotropin releasing hormone
- GHRH
- TRH
- GHIH
- PRL releasing factor
- prolactin inhibiting factor
3 major parts of the pituitary gland
- ant. pit.
- post. pit.
- pars intermediate
Other names for the ant. pit.? (3)
- pars distalis
- anterior lobe
- adenohypophysis
Other names for the post. pit.? (3)
- pars nervosa
- posterior lobe
- neurohypophysis
Other name for the pars intermediate? (1)
intermediate lobe
______ can damage/stretch the pit. stalk
head trauma
What is Rathke’s pouch? What does it form?
oral ectoderm that forms pars distalis and part of pars intermediate
What forms the infundibulum and pars nervosa?
neuroectoderm at the base of the brain
Terminals of neurons in the neurohypophysis
pituicytes (glial cells)
Where do the axon terminals secrete in the neurohypophysis?
into the blood
what role do the paraventricular nuclei and the supraoptic nuclei play?
synthesize sites for vasopressin and oxytocin
What happens when vasopressin acts on arginine vasopressin receptor 2?
enhances water retention of kidney (antidiuretic effect)
What happens when vasopressin acts on AVR1?
direct pressor effect via contraction of smooth muscle of the vascular system
Where is vasopressin made? Stored?
Made: hypothalamus
Stored; post. pit.
How is vasopressin released?
stimuli acting on hypothalamus
What are the two aa differences between vasopressin and oxytocin?
aa 3 and 8
What causes an increase in vasopressin release? (3)
- incr. plasma osmolality
- decr. blood vol
- decr. blood pressure
What has a permissive action and is require for max. antidiuresis?
aldosterone
______ stimulates contraction of myoepithelial cells surrounding the alveoli of mammary gland
oxytocin
T/F: Oxytocin follows a negative feedback loop
FALSE!!!!!!!!
How does the hypophyseal portal system work? (3)
- stimulated hypothalamic neurons secrete releasing/ inhibiting hormones into primary capillary plexus and the median eminence
- hypothalamic hormones travel through portal veins to ant. pit.- stimulate/inhibit release of ant. pit. hormones
- Ant. pit. hormones are secreted into secondary capillary plexus
Adenohypophysis Cells (5)
- thyrotrope
- coritcotrope
- gonadotrope
- mammotrope
- somatotrope
Hormone produced by thyrotrope?
TSH
Hormone produced by corticotrope?
ACTH and beta-LPH
Hormone produced by gonadotrope?
FSH and LH
Hormone produced by mammotrope?
prolactin
Hormone produced by somatotrope?
GH
What hypothalamic hormone controls FSH and LH? Positive or Negative?
GnRH; (+)
What hypothalamic hormone controls GH? P or N?
GHRH; (+)
What hypothalamic hormone controls GH and TSH? P or N?
SS;(-)
What does SS stand for?
somatotropin
What else is somatotropin called?
GHIH
What hypothalamic hormone controls TSH and Prolactin? P or N?
TRH; (+)
What hypothalamic hormone controls prolactin by inhibiting it?
DA (dopamine)
What hypothalamic hormone controls ACTH? P or N?
CRH; (+)
Growth Hormone (GH) (4)
- polypeptide
- made in somatotropes
- synergizes w/ insulin-like growth factors (IGFs) or acts alone
- release is stimulated by GHRH, inhibited by SS
Corticotropin/ Adrenocorticotropic hormone (ACTH) (3)
- released by CRH
- made in corticotropes
- classic negative feedback control
Thyroid-stimulating hormone (TSH) (5)
- glycoprotein
- made in thyrotropes
- released by TRH
- classic negative feedback control
- has effects on cortisol release too
Adrenals
- next to kidney
- left is larger than the right
- buried in peritoneal fat
- crossed by Phrenicoabdominal trunk
- color coded
T/F: the right adrenal may appose the vena cava
True
What does it mean that the adrenals are color coded?
Cortex - pale to yellowish
medulla - dark red to brown
Can the adrenal medulla regenerate after injury?
No; has a neural origin
Can the adrenal cortex regenerate after injury?
Yes
Is the zona arcuata (AKA glomerulosa) superficial or deep in the adrenal cortex?
superficial
What is synthesized in the zona arcuata?
mineralocorticoids
“salt”
Is the glomerulosa responsive to ACTH?
NO!
The _______ and ___________ make up the deeper portion of the adrenal cortex
zona fasciculata and reticularis
What is synthesized in the zona fasciculata and reticularis?
- glucocoricoids
- (some sex hormone synthesis)
(“sugar”)
Is the deeper portion of the adrenal cortex responsive to ACTH?
Yes
Site of sex hormone production in puberty?
Zona reticularis
Mineralocorticoids and glucocorticoids are structurally similar, except for one more hydroxyl group located here on the glucocorticoids
Carbon 17
where are binding proteins synthesized?
in the liver
how are coritsol and aldosterone metabolisized?
- hormones rendered water soluble
- excreted in urine
T/F: Mineralocorticoids are critical for life
True
Removal of adrenals without hormone replacement leads to death in a few days
Most important mineralocorticoid?
aldosterone
How is overstiumulation of aldosterone receptors prevented?
11-beta hydroxysteroid dehydrogenase converts coritsol to inactive cortisone
Which one, cortisol or cortisone, CANNOT bind to mineralocorticoid receptors?
cortisone
Physiological actions of aldosterone (4)
- increases Na+ reasbsorption from urine, saliva, and gastric juices
- increases Angiotensin II production
- decreases K+ by increasing renal secretion
- conservation of water follows conservation of sodium
How does aldosterone decrease K+ by increasing renal secretion?
- stimulates expression of sodium/potassium ATPase
- increases the number of these pumps
Aldosterone and Angiotensin II together do what?
drive salt seeking behavior
Aldosterone and Angiotensin II act upon the distal tubule and collecting duct for what purpose?
- resorption of renal sodium and water
- excretion of potassium
Water movement is _________
passive
Main function of cortisol?
stimulate gluconeogenesis
Other than stimulating gluconeogenesis, name 4 other actions of cortisol?
- production of blood glucose via action on liver gluconeogenic enzymes
- release of stores from liver and muscle
- insulin antagonism in the periphery (anti-insulin effect)
- similar effect to insulin on liver
How does cortisol have an anti-insulin effect?
stimulation of insulin growth factor binding protein-1
Excesses of glucocorticoids …. (3)
- affects many other tissues
- affect other hormonal systems
- can be useful clinically (eg- inflammation)
Clinical uses of glucocorticoid (4)
- inhibition of inflammatory response
- immune suppressant
- palliative therapy for arthritis, arthrosis
- replacement therapy for hypoadrenocorticism
How can glucocorticoids inhibit inflammatory responses?
- prevents capillary dilation
- extravasation of fluid into tissue spaces
- leukocyte migration
- fibrin deposition
- CT synthesis
- inhibit allergic responses
- mediated by inhibition of inflammatory mediators
Two cells types in the adrenal medulla
- ganglion cells
- chromaffin cells
Chromaffin cells in the adrenal medulla consist of two types. What are they?
- norepineprine secreting (15%)
- epinephrine secreting (85%)
________ is the rate limiting step for catecholamines synthesis
Tyrosine hydroxylase
What does 50% of epinephrine bind to in the blood for transport?
albumin
In the synthesis of catecholamines, tyrosine can be inhibited by what two substances?
- NE
- EPI
Catecholamines mediated by alpha-adrenergic receptors (2)
- vasoconstriction by norepinephrine
- liver glycogenolysis
Catecholamines mediated by beta-adrenergic receptors (4)
- increased heart rate/contractility
- bronchodilator
- adipose tissue lipolysis
- vasodilation by EPI
How is the release of NE or EPI from the adrenal medulla regulated? (3)
- sympathetic preganglionic neurons
- cortisol
- stress/hypoglycemia
In the PVN and SON, what cells produce vasopressin and oxytocin?
magnocellular neurosecretory cells
