Renal 7 Flashcards
aldosterone
a steroid hormone responsible for altering Na+ reabsorption and K+ excretion
renin-angiotensin-aldosterone system
an endocrine pathway that regulates blood Na+ levels
hyperkalemia
elevated levels of potassium in blood
decreased blood pressure controls..
aldosterone secretion that results in production angiotensin II
angiotensin II
triggers aldosterone release
Modifiers of aldosterone release
- increased osmolarity during dehydration inhibit release
- large drops in plasma Na+ directly stimulate aldosterone secretion
renin-angiotensin-system (RAS)
a multi-step pathway for maintaining blood pressure
renin
an enzyme involved in salt and water balance; main role to convert inactive plasma protein angiotensinogen to angiotensin I
renin is secreted by..
granular cells
3 stimuli for renin secretion
- low blood pressure
- sympathetic neurons activated by CVCC when blood pressure decreases terminate on granular cells
- paracrine feedback (prostaglandins) from macula densa cells signal to granular cells
angiotensin converting enzyme (ACE)
an enzyme produced in blood vessel endothelium that converts angiotensin I to angiotensin II
angiotensin II
travels to adrenal cortex and stimulates production of aldosterone
angiontensin II effects
- increases vasopressin secretion
- stimulates thirst
- one of the most potent vasoconstrictors
- ANG II receptors activated in CVCC increase sympathetic output to heart and blood vessels
- increase proximal tubule Na+ reabsorption
Pharmaceutical companies now use ____ inhibitors for the treatment of hypertension
angiotensin converting enzyme (ACE)
preventing the conversion of ANGI to ANGII leads to…
relaxation of the vasculature and lower blood pressure
atrial natriuretic peptide (ANP)
peptide hormone produced and secreted by specialized myocardial cells primarily in atria of the heart that promotes Na+ and water excretion
natriuresis
loss of Na+
brain natriuretic peptide (BNP)
a second type of natriuretic peptide produced in ventricles and in some neurons in the brain
How are ANPs released?
-increased blood volume stretches atrial wall during filling and atrial myocytes release ANP due to stretch
Aldosterone plays a critical role in K+ homeostasis by..
enhancing excretion in P cells
Range that K+ needs to be maintain within
3.5-5 mM
Alteration in K+ levels affects…
resting membrane potential of all cells
avoidance behaviours
prevent need for behavioural responses
-desert animals avoiding heat of day and becoming active at night
