Studied by 6 peopleTags & Description
What makes up the extracellular fluid?
Blood plasma
Interstitial fluid
What are the functions of the kidneys?
reg of extracellular fluid volume
reg of extracellular fluid osmolarity
reg of blood pressure
maintain ion concentration
reg pH
excrete wastes
production of hormones
What hormone is released by the kidney?
Erythropoietin
What is the normal pH?
7.4
What is the normal osmolality?
280mosm
What are the key ions in the kidney?
HCO3-, Na+ , K+ and Cl-
What are the metabolic products that are excreted by the kidneys?
Creatinine and urea
What is the medulla composed of?
8-15 renal pyramids
What is in the renal pyramids?
Multiple nephrons
What is transported in the nephrons to the renal pelvis?
Urine
What’s the centre of the kidney called?
Calyx
What is the function of the kidney?
Filter
Where does filtrate travel into?
Tubules
What happens in the tubules?
Reabsorbtion
What happens to the remainder of the filtrate that wasn’t reabsorbed into the bloodstream in the tubules?
Passes into the renal pelvis and excreted
What is the glomerulus?
Capillary bed
What are the two types of nephrones?
Cortical nephrons
Juxtamedullary nephrons
Where do the glomeri of the cortical nephrons originate?
Outer cortex
Where do the loops of henle of the cortical nephrons descend to?
The outer medulla
What’s “higher up“ cortical or juxtamedullary nephrons?
Cortical
The latter are “deeper” and posses a much longer loop of henle
Where do the loops of henle of the juxtamedullary nephrons descend to ?>
The inner medulla
What are the four functions of the nephrons?
Filtration
Absorbtion
Secretion
Excretion
How much blood does the kidney receive?
25% of cardiac output
1L/min
Where is arterial blood directed to in the kidneys?
From renal arteries to INTERLOBAR AND ARCUATE arteries to afferent arterioles
How does the blood return from the kidneys?
Via arcuate veins, interlobar veins into renal vein
Where is blood from afferent arteriole directed to?
Glomelular capillary
Where is blood from the glomerular capullaries directed to?
efferent arteioles
Where is blood from efferent arterioles directed to?
Peritubular capillaries
What the function of the glomerus?
Filtration
What’s the function of the peritubular capillaries?
Absorbtion
What are the glomerular capillaries surrounded by?
A rigid Bowman’s capsule
What kind of capillaries are in the glomerulus?
Fenestrated capillaries
What do fenestations allow to pass into the capsule?f
Dissolved solutes
NOT CELLS or PLATELETS
What does plasma pass through during glomerular filtration?
fenestrations
glomerular basement membranes
inner layer of bowmans capsule
What cells make up the inner layer of the bowmans capsule?
Podocytes
What structures extend out of the podocytes to wrap around the capillaries?
Pedicels/ foot processes
What are the spaces between pedicles of the podocytes?
Slit diaphrams that solutes have to pass between
What is the filtrate composed of?
Plasma and small amounts of proteins= albumin
Why isn’t Ca filtrated?
They are bound to larger proteins
Why are’t fatty acids filtered through?
They are lipophillic hence they need to bind to transported proteins which are far too large to be filtered through
What’s proteinuria?
Protein is filtered through into urine
What is proteinuria caused by?
Damage to slit diaphrams?
How are podocytes charged?
Negative charge
Why won’t albumin filter through?
They are negatively charged and are repelled by the neg charged podocytes and capillary walls
What the glomerular filtration rate?
vol of filtrate produced/ min
What’s the average GFR?
115ml/min females
180L/day
What’s the total blood volume?
5.5L
this means total blood volume is filtered every 40 mins?
What forces allow filtration in the glomerulus?
glomerular hydrostatic pressure - bowmans capsule pressure - glomerular oncotic pressure
→ opposed by plasma oncotic pressure
→ opposed by bowman’s capsule pressure
What’s the net filtration pressure in mm of mercury?
10mmHg
What’s oncotic pressure?
More proteins in bloodstream
Promotes water into bloodstream
Why is there no absorbtion in the glomerus?
Pressure difference
What’s haematocrit?
The red blood cells in blood
how much % of plasma is filtered through the glomerular capillaries?
20%
How is the GFR regulated?
intrinsically and extrinsically
What increases GFR?
autonomic nervous system if Na+ levels rise too high
what will a haemorrhage do to GFR?
reduced to retain blood volume
What is changed to control GFR?
resistance to afferent and efferent arterioles
→ hydrostatic pressure changes
What happens in the peritubular capillaries?
Absorbtion (low pressure)
What happens to GFR if afferenent arterioles are dilated?
increased
larger diameter= more GFR
larger diamter=less resistance= higher pressure = more filtrated
What happens if the diameter of the efferent arterioles is decreased?
Vaconstriction= build up of blood on the side of the glomerus= more pressure= higher GFR
what happens to the glomerular hudrostatic pressure of effereent arterioles are constricted>
increased
What happens if the efferent arterioles are REEAAALLY contracted?
less renal flow= large increaase in plasma oncotic pressure (that opposes filtration) = less GFR
What’s the glomerular hydrostatic pressure?
Pressure in the capsule fluid that drives the outward filtration
What does GFR stand for?
Glomerular filtration rate
What is the filtrtion freaction?
GFR/ renal plasma flow
Whats the renal plasma flow?
600ml/mon
How is the glomerular filtration rate controlled?
intrinsically and extrisincally
How will a haemorrhage impact GFR?
fall in GFR`
What happens if Na+ conc rises to the GFR?
Increases
More stuff exctreted
Does mean arterial pressure affect GFR?
No, as the kidney autoregulates itself.
What’s the myogenic response?
increase in blood pressure= constriction of afferent arterioles
What happens to the afferent arterioles if MAP falls?
dilation= more blood coming to glomerus despite sluggish trickling in due to low pressure
What apparatus controls the intrinsic renal autoregulation?
Juxtaglomerular
What cells are in the juxtaglomerular apparatus?
Macula Densa
What does the macula densa detect?
NaCl
What happens due to increased levels of NaCl?
Release of ATP by macula dense
constriction of afferent arteriole
less GFR
What division of the nervous system regultes nephrons and renal blood vessels?
Sympathetic only
What NT is released by the renal sympathetic nerves?
Noradrenline
What does noradrenaline cause?
Constriction of afferent arterioles
→ reduced GFR
What happens to urine output due to Noradrenaline?
Decreased
this prevents loss of blood
How is GFR measured?
by the renal clearance of any substance
what’s the equation for the renal clearance?
Cs * Ps = Us *V
clearance rate
plasma conc.
urine conc.
urine flow rate
What’s the urinary extretion rate in terms of GFR and secretion rate and reabsorbtion rate?
Urinary excretion rate= GFR + secretion rate- reabsorbtion rate
In what conditions is GFR= renal clearance?
the substance measured isn’t reabsorbed or secreted at the tubules
What waste product is used to measure GFR?
Creatinine
If the substance is filtered and partially reabsorbed, what is the relationship between GFR and renal plasma clearance?
Renal plasma clearance < GFR
gets rid of that substance better in the glomerus than the plasma because it comes back
If the substance is filtered and then secreted, what is the relationship between GFR and renal plasma clearance?
Renal plasma clearance > GFR
Note
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