Kidney I

What makes up the extracellular fluid?

Blood plasma

Interstitial fluid

What are the functions of the kidneys?

1. reg of extracellular fluid volume
2. reg of extracellular fluid osmolarity
3. reg of blood pressure
4. maintain ion concentration
5. reg pH
6. excrete wastes
7. 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?

1. fenestrations
2. glomerular basement membranes
3. 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