Week 21 Flashcards
Define osmolality
Concentration of solutes per kg of solvent
What does hypotonic ECF do to a cell?
Decreased osmolality
swollen cell
What does hypertonic ECF do to a cell?
Increased osmolality
Crenalated and shrunken call
Describe the plasma osmolality negative feedback loop
Osmoreceptors in the hypothalamus detect change
Thrist response
Posterior pituitary releases ADH
What is the impact of ADH release?
More ADH= Less urine at a higher concentrastion
Describe the mehanism of ADH?
- increase water permeability of late distal tubule and collecting duct by increasing aquaporin channels
- H2O is reuptaken
- Urine is more conc and less of it
- More urea moves into medullary region of collecting duct
- more NaCl reabsoprtion into thick ascending limb
How much urine does the body produce at normal ADH levels, Max ADH and min ADH?
Max ADH = 400 ml urine
Normal ADH= 1.4L urine
Min ADH= 23 L
Is the collecting duct going parallel or antiparallel to the loop of henle?
Collecting duct is going in the oppostie direction to teh loops of henle
How are the cortical and medullary impacted by ADH?
They’re ususally impermeable to water adn urea
But permeability increases in the presence of ADH
Describe the thirst mechanism
- increase plasma osmolality
- osmosreceptors in hypothalamus are stimulated
- hypothalamic thirst centre in lateral preoptic area stimulated
- sensation of thirst
What regulates blood pressure long term vs short term?
Long term= kidneys
Short term= baroreceptor reflex
How do kidneys regulate blood pressure?
By increasing sodium retention, water follows sodium, so more water retention increases blood pressure
Explain the blood volume feedback loop?
- decrease in blood volume
- decrease in arterial blood pressure
- Increased sympathetic activity
- stimulation of renin production
- decreased Na+ scretion and decreased urine vol
- Increased na+ and H2O retention
thus blood volume is restored
What are some causes of renin release?
Decreased sodium
decreased arteriole stretch causes renin release
increase in symp activity
Describe the renin-angiotensin-aldosterone system
- juxta make renin
- causes liver to make angiotensin
- Angiotensin 1 is converted to angiotensin 2 inthe lungs
- causing adrenal gland to increase aldosterone secretion
4.increases sodium reabsorption by distal tubule
What is aldosterone?
The sodium conserving hormone
steroid hormone, inside cell manipulates protein synthesis
Produced by the outer cortex of the adrenal gland
Describe the actions of aldosterone?
- Binds to basolateral receptor
2.Stimulates transcription of apical Na+ channels - Increase in NaCl reabsorbedi in distal tubule and collecting duct
- increased water reabsorbed via osmosis
- increased K+ secretion and activity of Na+ K+ ATPase
What three things could cause aldosterone release?
Renin angiotensisn system
Decrease plasma Na+
Increased plasma K+
What is the function of atrial natriuretic peptide?
Increased excretion of NaCl and H2O
Describe the mechanism to atrial natriuretic peptide.
- increase in blood volume
2.stretch of atrial myocardial cells - release of atrial natriuretic peptide
4.hypothalamus inhibits ADH release - Kidney decreases renin production
6.Adrenal cortex inhibits aldosterone
Why is pH regulation important?
Enzymer regulation
movement of ions
competition of ca2+ and H+for binding sites on albumin
Cardiac arrythmias
CNS function
Is the body a net producer of acid or alkali?
Acid
Krebs cycle makes CO2 and digestion makes H+
What is the body’s inbuilt buffer system?
When acid loses H+ it forms a conjugate base
eg. H2Co3
absorbs or releases H+ to make change in pH less drastic
How do the kindey and lungs help to buffer body pH as well?
Kidney balances by adding H+
Lungs balance by altering CO2 via ventilation
