excretion⚠️ Flashcards
suggest why a high intake of protein in the diet will be likely to result in a high concentration of urea in urine
- high protein means high concentration of amino acids
- amino acids cannot be stored
- amino acids deaminated
- ammonia enters orinthine cycle
- increased blood concentration of urea
what hormone is tested for in a pregnant test
human chorionic gonadotropin
name of cup shaped structure under glomerulus
bowmans capsule
explain how the glomerulus is able to perform its function
- afferent arteriole is wider than efferent arteriole
- build up of hydrostatic pressure
- endothelium of capillary walls has small pores
- this all allows ultrafiltration
suggest the effects of complete kidney failure on the composition of the blood
- increase in urea
- increase in salts
- increase in water
features of bowman’s capsule that allows it to function efficiently
- basement membrane stops removal of large molecules
- podocytes have projections which ensure gaps to allow passage of substances
nephritis is a condition in which the tissue of the glomerulus and proximal convoluted tubule becomes inflamed and damaged.
suggest two differences in the composition of the urine of a person with nephritis when compared to the urine of a person with healthy kidneys.
- proteins present
- glucose present
- blood cells present
how a channel protein ensure no positive ions go through
-channel has positive charge which repels positive ions
which cells produce ADH
-nerve cells= osmoreceptors
how is change of water potential of blood detected
- blood flows through hypothalamus
- osmoreceptors
where is ADH secreted from
posterior pituitary gland
ADH acts on the cells of …
the collecting duct
name of channel proteins that ADH causes to insert themselves into plasma membrane
aquaporins
suggest where ADH is removed from the blood and describe what then happens to the ADH molecule
- in the liver (as a protein)
- hydrolysis
- deamination
- orinthine cycle
- in the kidneys(as a small molecule)
- ultrafiltered from the blood as it is a small molecule
- not reabsorbed
- excreted
what is added to ammonia at the start of the ornithine cycle
co2 and ornithine
a pregnancy testing kit contains a testing ‘stick’ to detect a hormone in the urine
explain how the stick detects this pregnancy hormone
- testing for hCG
- hormone small so can pass from blood into filtrate
- immobilised antibodies on stick
- antibodies attached to marker
- hormone complementary to antibody so binds
- coloured line appears
name the tissue that lines the proximal convoluted tubule
epithelium
name the structures that line the proximal convoluted tubule
microvilli
Some of the changes observed between the glomerular filtrate and the urine are as a result of activity in the proximal convoluted tubule.
explain how these observed changes in concentration are brought about by the proximal convoluted tubule.
- selective reabsorption
- of glucose and amino acids
- by facilitated diffusion
- water follows by osmosis so concentration of ions and urea increases
blood from which blood vessel enters dialysis machine
artery
blood from which vessel leaves dialysis machine
vein
why is it necessary to add anticoagulant to blood entering dialysis
to prevent blood clots during dialysis
why does the dialysis fluid used in peritoneal dialysis contain dextrose solution rather than water alone?
- dextrose reduces wp of dialysis fluid
- kidney function is to remove excess water from blood
- if it was water alone then water would enter cells by osmosis causing them to burst
where in the nephron is glucose selectively reabsorbed into the blood capillaries
proximal convoluted tubule
which regions of the nephron are present in the cortex
- proximal convoluted tubule
- glomerulus
- distal convoluted tubule
- top of collecting duct
where are podocytes present
lining the bowmans capsule
explain how the longer loop of Henle is able to assist the desert kangaroo rat in preventing excessive water loss
- more ions pumped into medulla
- builds up greater wp gradient
- allows more water to be reabsorbed from collecting duct
state type of drug that can be misused in body building
anabolic steroids
explain changes in fluid composition from blood to urine
- large molecules cannot enter filtrate
- basement membrane prevents large molecules and erythrocytes reaching Bowmans capsule
- all glucose and amino acids reabsorbed at proximal convoluted tubule
- some ions reabsorbed
- urea concentration increases between filtrate and urine due to movement of urea into tubule
what is absorbed in the proximal convoluted tubule
into what are these absorbed
- most of the water
- some salts
-into blood capillaries
in what part of the nephron are walls impermeable to water
-ascending limb of loop of henle
in what part of the nephron is glucose reabsorbed into blood
proximal convoluted tubule
on what part of the nephron does ADH act
-collecting duct walls
what part of the nephron contains podocytes
bowmans capsule
where in the nephron is most water reabsorbed into blood
proximal convoluted tubule
explain the role of the loop of Henle in the production of urine
- role of loop of henle is to cause decrease in wp in medulla
- in ascending limb, active transport of solutes outwards
- walls of descending limb are permeable to water
- water removed from descending limb
- wp of tissues surrounding collecting duct is lower than fluid inside
- water removed from filtrate in collecting duct
function of microvilli in PCT
increases SA for reabsorption
does DCT or PCT have higher urea concentration and why
DCT as water is removed earlier in nephron
