Renal Flashcards
Main functions of the Kidneys
1) Regulation of water and electrolyte balance
2) Regulation of arterial pressure
3) Excretion of metabolic waste products or foreign chemicals from the body
4) Regulation of blood pH
5) Regulation of erythrocyte production
6) Regulation of hormone production
7) Regulating blood glucose
Homeostasis
Blood essentially.
What happens when the kidney goes wrong
1) Swelling
2) High blood pressure
3) Shortness of breath
4) Fatigue
5) Nausea
Osmosis
The movement of water through a selectively permeable membrane
1) from an area of lower solute concentration
2) to an area of higher solute concentration
Osmolarity
A measure of the osmotic pressure exerted by a solution across a perfect semi-permeable membrane compared to pure water
basically only concentration of particles needed
Tonicity
The concentration of a solute and it’s ability to cross a semi permeable membrane.
The difference is well illustrated in Urea
where you got some water passing through into cytosol
Hypertonic: The solution has a higher POsm, so water leaves, and causes cell shirnkage
Why maintain osmolarity
1) Setting membrane potential
2) generating electrical activity in nerve and muscle
3) initiation of muscle contraction
4) Providing energy for the uptake of nutrients and the expulsion of waste products
5) Generation of intracellular signaling cascades.
The make up of the fucken human body
A 70kg male is 60% fluid of that fluid 2/3 is intracellular fluid, 1/3 is extracellular fluid 80% is interstitial fluid 20% is plasma
Major sources of water intake
1) Metabolism 8% 200ml
2) Foods 28%
700ml
3) Beverages 64%
1600ml
Major sources of water output
1) Feces 4% 100ml 2) Lungs 12% 300ml Skin 24% 600ml Urine 60% 1500ml
Electrolyte concentration of blood
Sodium, chloride and calcium ions have high extracellular
Potassium has high intracellular
Water stats
Filtration 180
Reabsorption 178.6
Excretion 1.4
Sodium
Filtration 25560
Reabsorption 25410
Excretion
150
Glucose
Filtration 180
Reabsorption 180
Creatinine
- 8
1. 8
Glmerular filtration rate
about 25% of total renal plasma flow
about 180 L/day
it’s really similar to solute concentration and similar to plasma
It lacks proteins and other high molecular weight compounds-obviously.
Why is glomerular filtration rate relatively constant
Because Glomerular filtration rate is relatively constant
Renal blood flow is relatively constant
Urine output is directly proportional to renal pressure.
GBHP
The only capillary bed that has arterioles before and after to it.
This allows for tight regulation of pressure gradients to maintain near constant glomerular filtration rate.
Glomerular blood hydrostatic pressure stats
Glomerular BP is the average of the Afferent arteriole P and Efferent arteriole P
Increases in arterial pressure can be buffered by vasoconstriction of arteriole
Decreases in pressure can be buffered by vasoconstriction of efferent arteriole
Capsular hydrostatic pressure is exerted by
The elastic recoil of the glomerular capsule (15mmHg)
Hormonal regulation of Glomerular filtration
Angiotensin II via vasoconstriction of afferent and efferent arterioles
Atrial Natriuetic relaxation of mesangial cells, increase SA for filtration via relaxation process
How is Glomerular filtration regulated
Autoregulation
Neural
Hormonal
Anything that alters the glomerular hydrostatic blood pressure
and anything that alters the surface area available for filtration.
Tubuloglomerular feedback
1) Increased GFR
2) Increased tubular flow rate
3) Increased tubular Na+,Cl-, water content sensed by macula densa cells
4) Juxtaglomerular apparatus NO release decreased
5) Afferent arteriole vasoconstriction
The role of cortical nephrons
dilute urine
The role of juxtamedullary nephrons
important in the production of concentrated urine
What happens in the proximal convoluted tubule
largest amount of solute and water reabsorption from filtered fluid occurs here
It has hydrogen ion antiporters and glucose sodium symporters
And it has a highly developed brush border that increases surface area
60% glomerular filtrate
60%NaCl and water
100% glucose
Characteristics of proximal convoluted tubule
Highly active in membrane transport processes with reabsorption of water, ions, and glucose
Highly developed brush border increasing surface area
Active transport in PCT
Sodium is pumped into the interstitial space by Na K+ ATPase on basal surface on epithelial
Na+move into tubule cell via glucose antiporters and symporters
Glucose and other solutes then diffuse down concentration gradient
Na+ movement then allows water movement via osmosis
Osmolarity in proximal convoluted tubule similar to plasma
What does the renal capsule do
It’s a physical barrier, and protection against trauma
What does the adipose capsule do
1) It’s padding, physical protection
2) Maintains the position of the kidneys
What does the renal fascia do
It anchors the kidneys to the surrounding structures
Whats the thing between 2 medullary pyramids
Renal columns
Write out the pathway of blood from renal artery to vein
1) Renal artery
2) Segmental artery
3) Interlobar artery
4) Arcuate artery
5) Cortical radiate
6) Afferent arteriole
7) Efferent arteriole
8) vasa recta-in the medulla
9) Peritubular capillaries in the Cortex
10) Cortical radiate/interlobular veins
11) arcuate vein
12) interlobar vein
13) renal vein
What is the endothelium of the renal corpuscle
The glomerulus, it is a knot of capillaries
What is the epithelium of the renal corpuscle
It is the Bowman’s capsule
The visceral epithelium is the podocytes
The parietal epithelium is simple squamous epithelium
What is the basal lamina made up of
It’s made up of podocyte+ Endothelial cell
What is the electrolyte concentration in Intracellular fluid
Sodium=10mM
Potassium=140mM
Cl=4mM
What is the electrolyte concentration of extracellular fluid
Sodium=145mM
Potassium=5mM
Cl=110mM
Function of the descending loop of henle
Low permeability to ions and urea, but highly permeable to water
At the bottom of the loop of Henle the filtrate is very concentrated at 1200mOsmol/L
Thick ascending loop of Henle
sodium impermeable to water. Sodium, potassium, and chloride are actively reabsorbed
By the time the filtrate gets to the top of the loop of Henele it is very dilute
10mOsmol/L
What happens at the distal convoluted tubule and collecting duct
Additional reabsorption of NaCl
Water permeability dependent on ADH.
ADH
acts on the last part of the convoluted distal tubule and the collecting duct.
Aquaporin 2 added onto the APICAL MEMBRANE OF PRINCIPLE CELLS
the basolateral membrane is always relatively permeable to water
What does alcohol do
Alcohol inhibits ADH, resulting in dilute urine and dehydration
How is ADH made
ADH is made in the hypothalamus and stored in the vesicles in the posterior pituitary.
Osmoreceptors innervating the hypothalamus sense an increase in sodium concentration and an increase in osmolarity.
A signal is sent to the posterior pituitary and ADH is released into the blood stream
Osmoreceptors
Osmoreceptors have “stretch-inhibited” cation channels. When the cell shrinks due to hypertonic stimulus, the cation channels open, and the sodium entering the cells triggers action potentials
When is ADH activated
It increases as osmolarity increases
This is sensed by the osmoreceptors in the hypothalamus and baroreceptors in the heart and large vessels
and this triggers more ADH to be made in the posterior pituitary
ADH release sensitivity
Under 280 is when it usually gets released,
If the blood volume is low, ADH is more sensitive
If the blood volume is high, the ADH release is less sensitive
Renin-Angiotensin-Aldosterone
Important in maintaining sodium balance and blood pressure regulation.
This is detected by sodium from the juxtaglomerular apparatus
Renin triggers
1) Low salt concentration in the distal tubule
1) Macula densa cells respond to a decrease in Salt content by increasing prostaglandins
2) Decreased perfusion pressure
a) A decrease in pressure in afferent arteriole also acts on the juxtaglomerular cells to cause the release of renin
Increased sympathetic activity
Angiotensin II
Potent vasoconstrictor, thus it decreases glomerular filtration by vasoconstricting the afferent arterioles
2) It has a small direct effect on reabsorption in the proximal convoluted tubule
3) Stimulates release of aldosterone from the adrenal cortex
Aldosterone
acts on distal tubule and collecting ducts to increase transcription of Sodium/potassium ATPas pumps thus increasing sodium reabsorption and potassium excretion
