5.2-kidneys and liver Flashcards
What is excretion?
The removal of metabolic waste from the body.
What are the 2 blood supplies of the liver?
Hepatic artery
Hepatic portal vein
What does the hepatic artery do?
Brings oxygenated blood from the heart, supplying the liver with oxygen for aerobic respiration.
Why is the hepatic portal vein important?
Is brings deoxygenated blood from the digestive system to the liver- concentrations of substances will be uncontrolled because they’ve just entered the body trough the digestive system, so may contain toxic compounds which need to have their concentrations adjusted before they circulate the body.
What does blood leave the liver through?
The hepatic vein
What does the bile duct do?
Carries bile from the liver to the gall bladder
what is metabolic waste?
a substance that is produced in excess by the metabolic processes in the cells, it may become toxic.
what is the liver divided into?
lobes, which are further divided into lobules.
what is the shape of a lobule?
cylindrical
what is a kupffer cell?
a specialised macropage
what do kupffer cells do?
move about in the sinusoid, yeeting red blood cells (breaking down and recycling them)
what is one of the products of haemoglobin breakdown?
bilirubin, one of the bile pigments secreted as part of the bile.
what is at the centre of each lobule?
a branch of the hepatic vein known as the intra-lobular vessel
what is the shape of a hepatocyte?
simple cuboidal shape with many microvilli
what are the functions of the liver?
control of blood glucose, amino acid and lipid levels
synthesis of bile, plasma proteins, cholesterol
synthesis of RBCs in the fetus
storage of vitamins a,d, b12, iron, glycogen
detoxification of drugs and alcohol
breakdown of hormones
destruction of RBCs
where in the liver is glycogen stored?
granules in the cytoplasm of hepatocytes
what are 2 enzymes found in the liver that detoxify substances?
catalase
cytochrome p450
what does catalase do?
converts hydrogen peroxide into oxygen and water
what does cytochrome p450 do?
it’s a group of enzymes used to breakdown drugs including cocaine.
what can fatty liver lead to?
alcohol related hepatitis
cirrhosis
what causes fatty liver?
if the liver has to detoxify too much alcohol it uses up its stores of NAD and has insufficient left to deal with fatty acids, because NAD is also required to breakdown fatty acids for use in respiration. these fatty acids are converted back to lipids and stored as fat in the hepatocytes.
what is the equation for deamination?
amino acid + oxygen–> keto acid + ammonia
why must ammonia not be allowed to accumulate?
it’s v soluble and highly toxic
what is the cortex?
the outer region of the kidney
what is the medulla?
the inner region of the kidney
what is the pelvis?
the white centre part that leads into the ureter
what is ultrafiltration?
filtration of the blood at a molecular level under pressure
what is osmoregulation?
the control of water potential in the body.
how do we gain water?
drinking
respiration
food
how do we lose water?
breathing
faesces
urine
sweat
what detects water potential in blood?
osmoreceptors in hypothalamus
what releases ADH?
posterior pituitary
what is the effect of ADH on the collecting duct?
makes walls more permeable
what does increase of ADH do to water potential of blood?
increases it
what effect does ADH have on water potential of urine?
lower-more concentrated urine.
what are the excretory organs?
lungs
liver
skin
kidneys
what are inter-lobular vessels?
branches of the hepatic artery and hepatic portal vein
what is the passage of blood through the liver?
hepatic artery/hepatic portal vein–>branched (inter-lobular vessel) –>sinusoid –>branch of hepatic vein (intra-lobular vessel) –> hepatic vein
where is bile released?
into the bile canaliculi
what do the bile canaliculi join together to form?
the bile duct
what are some metabolic functions of a hepatocyte?
protein synthesis
transformation and storage of carbohydrates
synthesis of cholesterol and bile salts
detoxification
which enzyme catalyses the breakdown of alcohol initially?
ethanol dehydrogenase
what does alcohol get turned into when detoxified?
ethanal–ethanoic acid–acetyl coenzyme A
what happens to the H atoms that leave alcohol when it gets oxidised?
combine with NAD to form reduced NAD
what is the summary equation for the ornithine cycle?
ammonia + C02 –> urea + water
what is a section of the kidney called?
nephron
blood comes into the glomerulus through the…
afferent arteriole
blood leaves the glomerulus through the…
efferent arteriole
whats wider the afferent or efferent arteriole?
afferent
how is the endothelium of the capillary adapted to its function in the bowmans capsule?
narrow gaps between endothelial cells
endothelial cells also contain pores called fenestrations
whats the basements membrane of the bowman’s capsule made of?
fine mesh of collagen fibres and glycoproteins
what’s the effect of the basement membrane of the bowman’s capsule?
molecules with an Mr of over 69000 cant go through
what are the epithelial cells of the bowman’s capsule called?
podocytes
what’s the shape of a podocyte?
many finger-like projections, called major processes. on each major process there’s a minor process, or foot process.
what do the minor processes do?
hold the epithelial cells away from the endothelium of the capillary, ensuring there are gaps between the cells so fluid from the glomerulus can pass between them into the lumen of the bowman’s capsule.
overall, what are the adaptations of the bowman’s capsule and glomerulus that help them carry out their function?
afferent arteriole > efferent arteriole fenestrations gaps between endothelial cells basement membrane podocytes
what, in the blood, goes into the glomerular filtrate?
amino acids
glucose
urea
mineral ions
what happens to water potential in the descending loop of henle?
decreased
what happens to water potential in the ascending loop of henle?
increased
what happens to water potential in the collecting duct?
decreased
how are the cells lining the proximal convoluted tubule adapted for reabsorption?
membrane in contact w tubule fluid highly folded into microvilli, other membrane also folded
cell membrane has cotransport protiens
membrane next to capillary has Na+/K+ pump
cytoplasm has many mitochondria
why are microvilli on the proximal convoluted tubule important?
they increase surface area for reabsorption
what gets pumped out of the cells lining the proximal convoluted tubule?
sodium
what gets pumped into the cells lining the proximal convoluted tubule?
potassium
how are glucose and amino acids selectively reabsorbed?
1) Na+ actively pumped out of lining cell
2) conc gradient of Na+ forms
3) Na+ from other side diffuse in through cotransport protein, carrying glucose or amino acid with it.
4) water moves into cell by osmosis
5) substances move through to blood and water follows.
what is the arrangement of the loop of Henle known as?
a hairpin countercurrent multiplier system
the upper portion of the ascending limb of the loop of henle is…
impermeable to water.
what happens to water potential as you go down the loop of henle?
becomes more negative.
what happens in the ascending loop of henle?
mineral ions leave. at the bottom this happens by diffusion, at the top this happens by active transport.
on a cool day or a day where you’ve drunk a lot of water and don’t need to conserve that much, what happens to the walls of the collecting duct?
become less permeable-less water is reabsorbed.
what are the water permeable channels called in the collecting duct wall?
aquaporins
what’s it called when the cell surface membrane folds inwards?
it invaginates
hahahahhaaha
how does adh work in the collecting duct?
detected by cell surface receptors
causes a chain of enzyme controlled reactions inside cell
end result of reactions is to cause vesicles containing aquaporins to fuse to membrane
more water can be reabsorbed.
what happens in the walls of the collecting duct when adh levels fall?
call membrane invaginates to create new vesicles that remove aquaporins from membrane.
what type of cell produce and release adh?
neurosecretory cells (specialised neurones)
where is adh stored?
vesicles in the terminal bulb of the posterior pituatary
what is the glomerular filtrate rate (GFR)?
the rate at which fluid enters the nephrons.
what are monoclonal antibodies?
antibodies made from 1 type of cell, specific to one complimentary molecule.
what is renal dialysis?
a mechanism used to artificially regulate the concentrations of solutes in the blood.
how can kidney function be assessed?
estimating GFR
analysing urine for proteins
what is a normal GFR value?
90-120 cm3/min
what GFR figure indicates chronic kidney disease?
below 60cm3/min
what GFR figure indicates kidney failure?
below 15cm3/min
what are possible causes of kidney failure?
diabetes mellitus
heart disease
hypertension
infection
what are the main treatments for kidney failure?
renal dialysis
kidney transplant
what are the 2 types of renal dialysis?
haemodialysis
peritoneal dialysis
what is added in haemodialysis to reduce clotting?
heparin
what happens during haemodialysis?
blood is passed into a machine containing an artificial dialysis membrane. the artificial capillaries are surrounded by dialysis fluid flowing the opposite way (countercurrent flow).
what has to happen before the blood from haemodialysis is returned to the body?
remove any bubbles
how often and where is haemodialysis usually done?
2-3 times a week, a few hours a session, at a clinic.
what is the peritoneum?
abdominal membrane
what happens during PD?
dialysis membrane is the peritoneum. a permanent tube is implanted in the abdomen via surgery . dialysis solution is poured through the tube, filling the space between the abdominal wall and organs.
how long does the dialysis fluid stay in the body during PD?
several hours
when can PD be carried out?
home or work
what is PD sometimes called?
ambulatory dialysis (ambulatory=adapted to walking around)
what must dialysis be combined with?
carefully monitored diet.
what are the advantages of kidney transplants?
freedom fro time-consuming renal dialysis
feeling physically fitter
improved QOL, able to travel
improved self image-no longer chronically ill
what are the disadvantages of kidney transplants?
need to take immunosuppressant drugs
need for major surgery under general anaesthetic
need for regular checks for signs of rejection
side effects of immunosuppresant drugs
what are some side effects of immunosuppresant drugs?
fluid retention
high blood pressure
susceptibility to infections
what useful things can urine be tested for?
glucose alcohol-levels in drivers recreational drugs hCG anabolic steroids-improper use in sport
what would glucose in the urine suggest?
diabetes
how long does marijuana stay in the urine after a single use?
7 days
what hormone is released once a human embryo is implanted in the uterine lining?
human chorionic gonadotrophin (hCG)
what enzyme catalyses ethanal turning into ethanoic acid in the liver?
ethanal dehydrogenase
what are the three molecules that make up the cycle part of the ornithine cycle (the intermediates)?
citrulline-arginine-ornithine
what happens in the descending loop of henle?
Na+ and Cl- ions diffuse in and water osmoseseses out
what is the path the blood takes during haemodialysis?
body-arterial pressure monitor-blood pump-heparin pump-dialyser inflow pressure monitor-dialyser-venous pressure monitor-air detector clamp-body
what’s the purpose of the heparin pump?
to prevent clotting
what do pregnancy test kits use?
monoclonal antibodies which bind to hCG in urine
what does testing for anabolic steroids involve?
analysing a urine sample in a lab using gas chromatography
WHAT IS THE FATTER VESSEL ENTERING THE LIVER
THE HEPATIC PORTAL VEIN
WHATS THE THINNER VESSEL ENTERING THE LIVER
HEPATIC ARTERY
WHAT DOES THE HEPATIC PORTAL VEIN LOOK LIKE COMING INTO THE LIVER
BRANCHED
FATTER
what happens to bile?
stored in gallbladder, released into duodenum when needed, bile salts+acids mostly reabsorbed into body
surface area of a sphere???
4πr squared
volume of a sphere??
4/3πr cubed
why are podocytes unable to undergo mitosis apparently?
already are , differentiated so cannot divide
are in G0 phase of cell cycle
shape is (too) irregular / asymmetrical so cannot divide
cytoskeleton cannot function / spindle (fibres) cannot form
(if mitosis occurred) it would alter , number / size ,
of the , gaps / fenestrations
it would alter an aspect of ultrafiltration
