kidney Flashcards
What is the function of the kidney?
- excretion
- osmoregulation
- filter nitrogenous waste products out of urea
- maintain water balance of blood and pH
What is the function of ureter?
Carries urine to bladder
What is the function of bladder?
Muscular sac that stores urine
What is the function of urethra?
Where urine passes out of the body from
What is the function of renal artery?
Brings oxygenated blood to the kidney
What is the function of renal vein?
Takes deoxygenated blood away from kidney
Where does ultrafiltration take place?
- renal artery leads to smaller arterioles in Cortex
- arteriole splits into glomerulus (bundle of capillaries looped in a hollow ball) and hollow ball is called bowmans capsule
What is the afferent arteriole?
The arteriole that takes blood into each glomerulus of the nephron
What does the efferent arteriole do?
Takes filtered blood away from glomerulus
- smaller in diameter than afferent arteriole so blood in glomerulus is under high pressure
- the high pressure forces liquid and small molecules in the blood out of the capillary and into bowmans capsule
Describe ultrafiltration
- substances are filtered out of the blood and enter tubules in kidneys
- blood enters glomerulus, bundle of capillaries looped inside a hollow ball called bowman’s capsule
- blood in glomerulus in under high pressure because it enters through afferent arteriole and leaves via the smaller efferent arteriole
- high pressure forces liquid and small molecules in blood out of capillary and into bowman’s capsule
- liquid and small molecules pass through capillary wall, basement membrane, epithelium of bowman’s capsule
- larger molecules like proteins and blood cells can’t pass through so stay in blood
What are the 3 layers to enter the bowman’s capsule?
Capillary wall
Basement membrane
Epithelium
What is selective reabsorption?
- useful substances leave tubules of nephrons and enter capillary network that’s wrapped around them
- epithelium of wall of PCT has microvilli for large surface area for reabsorption of useful materials from filtrate in tubules to blood in capillaries
- useful salutes such as glucose, amino acids, vitamins, salts are reabsorbed along PCT via active transport and diffusion
- some urea is reabsorbed by diffusion
- water enters blood via osmosis as water potential is lower than of filtrate
- water is reabsorbed from loop of Henle, DCT, collecting duct
- filtrate that stays is urine which passes to ureter and bladder
What is urine usually made up of?
Water
Dissolved salts
Urea
Other such as hormones and excess vitamins
What does urine not usually contain?
Proteins and blood cells - as too big to be filtered out of blood
Glucose, amino acids and vitamins - actively reabsorbed back into the blood
What happens if water potential of blood is too low? Aka dehydration
More water is reabsorbed by osmosis into the blood from tubules of the nephrons
So urine is more concentrated so less water is lost during excretion