Excretion Flashcards
Which organs excrete?
skin
kidneys
lungs
What does the skin excrete?
water, salt & urea
What are the structures of skin?
epidermis
sebaceous gland
hair
hair follicle
muscle
sweat gland
sensory neuron
capillary loop
subcutaneous fat
What is subcutaneous fat for?
insulation
What do kidneys excrete?
water, urea (from breakdown of amino acids in liver), salt
- through ultrafiltration & selective reabsorption
What are the structures of the kidney?
nephron - individual filtering & reabsorption units
renal artery
renal vein
ureter
cortex - contains filtering part of nephron
pyramids - water reabsorption
medulla
pelvis - collects urine from nephrons
What are the structures of the nephron?
- glomerulus
- bowmans capsule - ultrafiltration
- proximal convulated tubule - reabsorbs all glucose back into blood, by active transport
- loop of henle - majority of material is reabsorbed by osmosis
- distal convulated tubule - salt reabsorption occours
- collecting duct - reabsorbs more/less water based on hydration
What are the features of where ultrafiltration takes place?
- Bowmans capsule - top of nephrons walls allow ultrafiltration
- golmerulus - capillaries with leaky walls to allow ultrafiltration
- narrow blood vessels - increases pressure in glomerulus to force molecules through wall
What do lungs excrete?
CO2 (from respiration) & water (from respiration)
What is glycogen?
insoluble polymer of glucose
Why don’t cells taking up glucose affect water potential?
glycogen is insoluble
What is excretion?
removal of waste products of metabolic reactions that have taken place inside the body
What is osmoregulation?
how kidney controls concentration of blood by retention of water/removal of excess water via urine
Where does ultrafiltration take place?
glomerulus & bowmans capsule
What happens in ultrafiltration?
blood is filtered & small molecules move to nephron, large molecules & blood cells stay in blood
Which molecules are filtered in ultrafiltration and why?
- water
- urea
- glucose
- salt
small enough
Which molecules aren’t filtered in ultrafiltration and why?
- hormones/proteins/antibodies
- platelets/white & red blood cells
too large
What is urine controlled by?
ADH
- targets wall of collecting duct, so its more/less permeable to water
- more/less water is reabsorbed into blood
- controls urine volume & concentration
What happens to urine when you are well hydrated?
- high volume - removing excess water
- light colour - more dilute
What happens to urine when you aren’t well hydrated?
- low volume - retaining water
- darker colour - more concentrated
What happens in the collecting duct when you are over hydrated?
- less ADH produced
- walls of collecting duct are less permeable to water - less reabsorption
What happens in the collecting duct when you are dehydrated?
- more ADH produced
- walls of collecting duct are more permeable to water - more reabsorption
What does selective reabsorption do?
all glucose, most salt, most water needs reabsorbed back into blood
- happens by osmosis & active transport
What features are there in the urinary system?
- aorta
- vena cava
- kidneys - filters blood & produces urine
- bladder - stores urine
- urethra - tube used to empty bladder
- sphincter - ring of muscle (relaxes to empty bladder)
- ureter - tube urine travels down to get from urine to bladder
- renal artery
- renal vein
