Ion and Water Balance 5: Kidney Hormones Flashcards
what kinds of hormones affect kidney function (2)
- steroid hormones
- peptide hormones
kidney function: steroid hormones (2)
- slow response
- eg. aldosterone
kidney function: peptide hormones (2)
- rapid response
- eg. vasopressin
what is involved in the regulation of urinary function (2)
- hormones
- dietary factors
what dietary factors affect urinary function (2)
- diuretics
- antidiuretics
diuretics
- stimulate excretion of water
antidiuretics
- reduce excretion of water
what hormones are involved in extrinsic regulation of glomerular filtration rate (3)
- vasopressin (antidiuretic hormone, ADH)
- renin-angiotensin-aldosterone (RAA) pathway
- atrial natriuretic peptide (ANP)
what kind of hormone is vasopressin/antidiuretic hormone
- peptide hormone
where is vasopressin/ADH produced/released (2)
- produced in the hypothalamus
- released by posterior pituitary gland
what does vasopressin/ADH do (2)
- increases water reabsorption from the collecting duct
- increases the number of aquaporins
what is the release of vasopressin/ADH stimulated by (1) and what is it detected by (1)
- increasing plasma osmolarity
- detected by osmoreceptors in the hypothalamus
what is the release of vasopressin/ADG inhibited by (2) and what is it detected by (2)
- alcohol and caffeine
- increasing blood pressure
- detected by stretch receptors in atria
- detected by baroreceptors in carotid and aortic bodies
what is the mechanism by which vasopressin increases cell permeability (4)
- vasopressin binds G-protein-linked receptor
- receptor activates adenylate cyclase, increasing cAMP and activating protein kinase A
- phosphorylation of cytoskeletal and vesicle proteins occur
- triggers translocation of vesicles containing pre-synthesized aquaporins to the cell membrane, with insertion of aquaporins
where does vasopressin/ADH have the largest effect
- stimulates water uptake most in the collecting duct
when is the renin-angiotensin-aldosterone pathway initiated
- when BP or GFR is lower than normal
how is the RAA pathway initiated
- renin is secreted
describe the RAA pathway steps (3)
- secreted renin converts angiotensinogen to angiotensin I
- angiotensin converting enzyme (ACE) on epithelia of blood vessels converts angiotensin I to angiotensin II
- angiotensin II causes synthesis and release of aldosterone from adrenal cortex
angiotensinogen
- inactive protein in plasma
what is the role of the RAA pathway
- helps regulate blood pressure
how does the RAA pathway help regulate blood pressure
- angiotensin II is a vasoconstrictor
- aldosterone increases Na+ (and water) retention
how does angiotensin II vasoconstriction regulate blood pressure
- raises blood pressure by increasing resistance
how does aldosterone increase in Na+ and water retention regulate blood pressure
- raises blood pressure by increasing blood volume
where is aldosterone produced in tetrapods
- adrenal cortex
what kind of hormone is aldosterone (2)
- mineralcorticoid
- steroid hormone
what cells does aldosterone target (2)
- distal tube cells
- collecting duct cells
aside from the RAA pathway, what can stimulate aldosterone secretion
- increases in circulating K+
what does aldosterone do (2)
- stimulates Na+ reabsorption from urine, with water following by osmosis
- enhances K+ excretion
what is the mechanism by which aldosterone stimulates Na+ reabsorption (5)
- aldosterone enters the cell by diffusion
- it binds it its receptor, a transcription factor
- activated transcription factor stimulates transcription of transporter genes
- new transporter proteins are made in ER and exported in vesicles
- vesicles containing proteins are sent to the plasma membrane
where is atrial natriuretic peptide (ANP) produced
- specialized cells within the atria
what stimulates ANP secretion
- in response to stretch associated with increase in blood volume
what are the main outcomes of ANP secretion (2)
- increases urine output
- lowers blood pressure and volume
what pathways/systems does ANP affect (3)
- RAA pathway
- GFR
- vasopressive
how does ANP affect the RAA pathway (2)
- acts as an agonist with the RAA pathway
- increases secretion of Na+ in urine
how does ANP affect the GFR (2)
- increases GFR by relaxing contractile cells
- results in increase of size of filtration slits of glomerulus
how does ANP affect vasopressin (2)
- inhibits secretion of vasopressin
- reduces water reabsorption
what will dehydration results in (3)
- ↓ blood volume
- ↓ blood pressure
- ↑ plasma osmolarity
how does the regulate acid-base balance in the body (2)
- primary regulation by rate of ventilation to alter CO2 levels
- fine-tuning with kidney
how do the kidneys fine-tune acid-base regulation (2)
- control secretion of H+
- control reabsorption of HCO3-
what can the kidneys do if the pH in the body is too low (2)
- increase secretion of H+
- increase reabsorption of HCO3-
how can medicine prevent acute mountain sickness in the kidneys
- limit reabsorption of HCO3-
which of the processes in the kidney can be regulated
- all: filtration, reabsorption, secretion and excretion
what is the class of hormones that affect kidney function
- endocrine hormones
what other systems does the regulation of urine formation interact with
- cardiovascular function and blood pressure
excretory control of homeostasis: increased water intake problem (2)
- increased plasma volume
- decreased plasma osmolarity
excretory control of homeostasis: increased water intake solution (2)
- increased urine volume
- no change in salt excretion
excretory control of homeostasis: increased water intake resolution
- decrease in plasma volume, and homeostasis
excretory control of homeostasis: increased salt intake problem (2)
- no change in plasma volume
- increased plasma osmolarity
excretory control of homeostasis:
increased salt intake solution (2)
- no change in urine volume
- increase in salt excretion
excretory control of homeostasis: increased salt intake resolution
- decreased plasma osmolarity, and homeostasis
why should we drink gatorade during exercise (3)
- exercise results in water loss and salt loss
- just drinking water would reduce plasma osmolarity, so water would still leave blood by osmosis
- low blood volume would result in lesser ability to control body temperature and perform well
