Physiology Flashcards
What is acidosis?
Decrease in pH <7.4
What is alkalosis?
Increase in pH > 7.4
What is normal blood pH?
pH 7.4
What is pH?
Power of hydrogenium (as H are very reactive so can act on proteins, too much= change function)
Only free H ions involved in pH balance
What is normal quantity of carbonic acid in the blood?
Depends on amount of C02 dissolved in the plasma
What is normal PC02 levels?
40mmHg
What is normal HC03 levels?
24mmHg
What is a normal GFR?
180L/day
What does the proximal convoluted tubule reabsorb?
NaCl, water AAs, glucose, anions, low molecular weight proteins
What does the distal tubule secrete and reabsorb?
Secretes- K, H
Reabsorb- NaCl, Water
What does the descending loop of henele cause reabsorption of ? How does this happen?
Water via aquaporins
Water follows higher conc. of Na and Cl (excreted from ascending loop) out into efferent arteriole (higher tonicity causes osmotic flow)
What does the ascending loop of henle cause reabsorption/ secretion of\?
Na, Cl
What is the simple function of the glomerulus?
Filtration- Reabsorption- Secretion
What is the blood flow to the kidneys?
1200mls/min (20-25% of cardiac output- therefore takes 5mins for who cardiac outflow to run through)
What is the function and purpose of hydrostatic and oncotic forces?
Colloid osmotic (oncotic) pressure- exerted by proteins (albumin) in a blood vessel's plasma, pulls water into the circulatory system (favour reabsorption) Hydrostatic Pressure- due to gravity, increases filtration by pushing fluid out of capillaries =Starlings Forces
Describe the pressures acting on a glomerulus that result in filtration/ reabsorption . What is the net filtration?
Hydrostatic (BP)- 55mmHg Fluid Pressure (created by Bowmans capsule)= 15mmHg Colloid Osmotic (oncotic)- 30mmHg 55- (30+15)=10mmHg filtration pressure
How do you increase pressure in glomerulus?
Short and wide afferent arterioles= little resistance to flow
long and narrow efferent arterioles= inc friction + resistance= Inc pressure + High resistance in efferent arterioles causes and increase in hydrostatic (filterative forces) up stream (afferent) so more will be taken out NOTE: causes a decrease in pressure down stream
What extrinsic control is there over GFR?
- Sympathetic- afferent + efferent vasoconstriction
- Circulating catecholamines (adrenaline + noradrenaline from adrenal medulla)- Inc blood flow to other organs so decreases GFR by decreasing hydrostatic pressure
- Ang 2- High Conc (afferent + efferent= normal), Low (Act of efferent to inc GFR)
What are the intrinsic controls over GFR?
Autoregulation- within 60-130mmHg
- Inc MAP= Afferent arteriolar constriction (prevents rise in glomerular pressure)
- Dec MAP= Afferent arteriolar dilation(try and inc pressure to keep filtration going)
How/ Why would autoregulation be overridden?
In seriously compromised BV/BP (eg./ haemorrhage) where autoregulation is over-ridden by sympathetic output (vasoconstriction) to liberate blood to immediately important organs- prolonged reduction can disrupt the kidneys role in homeostasis=death
What substances does the kidney reabsorb? How does it do this?
Glucose, Water, Na, Cl, urea via high TTp>Ppc (high osmolarity and low hydrostatic)
Explain the anatomy of the basement membrane
Epithelial Podrocytes- wrap around capillaries leaving filtration slits, podrocytes attach to BM via pedicles (foot process)
Basement Membrane- 3 layers, prevent plasma proteins from being filtered out of blood
Endothelium- large pores with solutes (plasma proteins and fluid can pass through but blood cells cannot)