Endocrine System Flashcards
What are the peptide hormones
All hormones made by the hypothalamus: GnRH, CRH, GHRH, ADH, oxytocin
All hormones made by the anterior pituitary: TSH, ACTH, LH, FSH, prolactin, GH
Glucagon and Insulin
Calcitonin and parathyroid hormone
What are the steroid hormones
All hormones made by the adrenal cortex: glucocorticoids, mineralcorticoids, androgenic steroids
All hormones made by the reproductive organs: progesterone, testosterone, estrogen
What are the amino acid derived hormones?
All hormones made by the adrenal medulla: epinephrine, norepinephrine
Triiodothyronine (T3) and thyroxine (T4)
G protein
Also known as guanine nucleotide-binding protein
A category of proteins that activate other things
Consists of three subunits: alpha, beta and gamma
How is G protein activated and what does the activated G protein do?
Becomes activated once a GTP molecule replaces the GDP molecule that was bound to the G protein, and the beta and gamma subunits dissociate from the alpha subunit
The G protein in the activated GPCR will then activate some effector, which leads to some message being sent
G protein couples receptors (GPCRs)
Cell surface receptors that initiate a secondary messenger response after binding to a peptide hormone (ligand) extracellularly
Once G protein is activated and dissociated into its subunits due to conformational changes, the subunits can then act upon intracellular second messages to propagate a signal
What are the second messengers
cAMP, IP3, DAG, Ca2+
What does the IP3/DAG pathway regulate?
Intracellular calcium levels
IP3 binds to calcium channels on the ER which triggers the activation and opening of calcium channels, releasing calcium ions into the cytosol
What is the adrenal cortex stimulated by?
ACTH from the anterior pituitary in response to stress –> releases glucocorticoids via second messenger cAMP
The adrenal cortex stimulates the secretion of which hormones?
Steroid hormones called corticosteroids which include glucocorticoids, mineralocorticoids and androgenic steroids
What is the adrenal medulla controlled by?
Directly controlled by the sympathetic nervous system
The adrenal medulla stimulates the secretion of what hormones?
Amino acid derived hormones called catecholamines which include adrenaline and noradrenaline
Catecholamines
Amino-acid derived hormones which include epinephrine (adrenaline) and norepinephrine (noradrenaline)
Secreted by the adrenal medulla
“Flight or fight” hormones secreted when facing acute stress
What kind of cells can catecholamines act on?
Any cell with complementary adrenergic receptors
What occurs when catecholamines are released?
Increase heart rate and quickly break down glucose into ATP to energize the body
Mineralocorticoids
- Aldosterone
- Hormones released by the adrenal cortex
- acts on the distal convoluted tubule and collecting duct to increase reabsorption of sodium (Na/Cl) and secretion of potassium/H+
- The active reabsorption of sodium into the plasma passively allows for the reabsorption of water into the blood which increases blood volume and pressure
Beta cells
Cells of the pancreas the secrete insulin to decrease blood glucose levels by targeting all three glucose storages that store glucose:
liver: converts glucose —> glycogen
muscles: converts glucose —> glycogen
adipose: converts glucose —> triglycerides
Graves’ disease
An autoimmune disorder that causes hyperthyroidism
The body’s autoimmune system mistakenly attacks the cells of the thyroid gland and thereby overstimulate it
Somatostatin
Hormone secreted by delta cells of the pancreas
Also known as growth hormone inhibiting hormone
Inhibits growth hormone (GH) secretion, Insulin and glucagon secretion
growth hormone is also known as somatotropin
What type of feedback is regulation of blood pH?
Negative feedback
Blood pH is regulated by homeostasis- receptors in blood vessels monitor the pH of the blood to determine if the body is breathing adequately
Ex: during exercise, our body produces energy through respiration, producing lots of carbon dioxide and lowering blood pH, once the blood becomes too acidic because of too much carbon dioxide, respiration increases to release excess carbon dioxide, bringing blood pH back to normal
difference between endocrine and exocrine systems:
endocrine system secretes hormones into the bloodstream while the exocrine system secretes enzymes or cellular secretions into ducts
where are peptide hormones produced?
peptide hormones are proteins synthesized by the rough ER and transported to the golgi for modification and packaging –> they are then secreted into secretory vesicles from the golgi by exocytosis
process of manufacturing peptide hormones
1) manufactured in rough ER as a larger pre-prohormone
2) cleaved in ER lumen to prohormone
3) cleaved again and modified with carbohydrates in golgi to final form
4) packaged by golgi into secretory vesicles for release via exocytosis
antidiuretic hormone
- direct, peptide hormone
- also called vasopressin
- secreted by the hypothalamus but stored and released by the posterior pituitary gland
- targets nephrons of kidneys to increase water reabsorption and decrease urination by increasing permeability of the collecting duct by inserting more aquaporins
- produces more concentrated urine and helps body retain more water when dehydrated
- increases blood pressure and volume
