What does the afferent arterioles do?
carry blood** towards** the glomerulus
What does the efferent arterioles do?
carry blood **away **from the glomerulus
two steps
How is Urea produced?
The deanimation of Amino acid to produce Ammonia which then reacts with CO2 to produce Urea & Water
What are the two stages of Urine Producton?
Ultrafiltration & Selective reabsorption
what are the layers of the glomerular filtration membrane?
- Endothelium layer
- Basement membrane - made up of a network of collagen & Glycoproteins
- Epithelium layer - contains gaps inbetween them known as Podocytes
What are the main substances that make up to Glomerulus Filtrate?
Amino acids, water, glucose, salts, urea
Wha
What is the role of the basement membrane?
acts as a filter to stop large protein molecules from getting there
How does ultrafiltration occur?
Due to the difference in water potential between the plasma in the glomerular capillaries & filtrate
What are the 2 factors affecting the water potential between the capillaries & filtrate
Pressure & solute concentration
Which of the arterioles are wider?
Efferent or Afferent?
Afferent arteriole
Where does glucose reabsorption occur?
Proximal convoluted tubule
Where does reabsorption of water & salts occur?
Loop of Henle & collecting duct
Explain the process
How is glucose reabsorbed?
- Na+ ions are actively transported out of the cytoplasm of epithelial cells into the blood capillaries
- This causes a low conc of Na+ ions in the epithelial cells
- resulting in Na+ ions to diffuse into them using Co-transporter proteins whcih transport glucose along with it.
- the glucose molecules then diffuse from the epithelial cells into the capillaries down the conc gradient
there are 3
What are the adaptations of the proximal convoluted tubule and their roles?
- Contains microvilli - provides large SA for reabsorption
- Contains infoldings on the membrane near the blood capillaries - providing a large SA for transfer of molecules
- Many mitochondria - provides ATP for transport of Na+ ions
What is the role of the loop of Henule?
lowers the water potential of the tissue in the medulla
What happens in the Loop of Henule?
- Na+ & K+ ions are actively transported out of the LOP through active transport
- This decreases the WP in the interstital region causing water to diffuse into it by osmosis from the descending limb which eventually moves into the bloodstream
- this results in a more concentrated filtrate in the LOP causing the ions there to then also diffuse out into the interstital region
- up the ascending limb active transport then takes over again repeating the cycle
What is the name of the receptor which monitors the water potential of the blood?
& where is it found?
Osmoreceptors
they are found in the hypothalamus
What happens to the osmoreceptors when it detects a decrease in the WP in the blood?
WP means water potential
simple version
- a nerve impulse is sent along the sensory neurone to the posterior pitutary gland
- the PPG are stimulated to release antiduretic hormones
- the ADH enters the blood & travels to the kidneys causing it to reabsorb more water from the filtrate
