excretion Flashcards
deamination?
Amino acid + Oxygen -> Ammonia + Keto acid
adaptation of hepatocytes?
- cuboid with lots of microvilli, increase surface area
-lots of mitochondria
role of kupfer cells?
breakdown old erethrocytes, provide bile pigments
role of hepatocytes?
storage of glycogen, deamination, ornithine cycle, production of bile
3 roles of liver
-store glycogen
-detoxification (alcohol, cytochrome p450, catalase) using redox, methylation, combination w different molecules
-production of urea
filtration layers in glomerulus and bowman’s capsule
- fenestrated capillaries (gaps in capillaries allowing fluids to leave)
-basement membrane (prevents majority of large proteins from leaving)
-podocytes (finger-like projections on epithelia of Bowman’s capsule that stops capillary wall from touching wall to allow transfer)
define ultrafiltration
the forcing of fluid in the blood in the glomerulus to the Bowmans capsule in the nephron under high hydrostatic pressure.
How is pressure gradient maintained in bowman’s capsule and glomerulus during pressure filtration?
Wider afferent arteriole than efferent makes hydrostatic pressure higher in capillaries than bowman’s capsule.
Define selective reabsorption
The return of glucose and amino acids to the blood from the proximal convoluted tubule, co-transported with Na+ ions.
describe the process of selective reabsorption in the proximal convoluted tubule
- Na+ ions A.T out of cytoplasm to blood, decreasing conc. in cytoplasm.
- Na+ ions in PCT co-transport glucose/ amino acid down conc. gradient to cytoplasm
- Glucose and amino acids diffuse down concentration gradient into blood, decreasing water potential.
- Water leaves PCT and enters blood via osmosis down water potential gradient.
Describe the process of filtration in the loop of Henle.
- Na+ and Cl- ions A.T out of ascending limb, decreasing the water potential in the medulla
- A small amount of Na+ and Cl- ions also diffuse out of descending limb
- Water in descending limb leaves via osmosis, increasing Na+ and Cl- conc. in descending limb
- Na+ and Cl- now diffuse passively out of the descending limb, again decreasing the water potential in the medulla
- Causing water to also leave the collecting duct via osmosis
- Remaining solute is now urine and passed out to bladder.
define osmoregulation
the homeostatic control of the water potential of the blood
Why is osmoregulation important?
It ensures blood and tissue fluids remain isotonic so cells are not damaged by osmotic lysis
Describe the function of ADH
- ADH secreted into blood by posterior pituitary gland binds to receptors on cells of collecting duct
2.Cell signalling triggered by ADH causes vesicles containing aquaporins to travel towards the CSM - Vesicles fuse to the CSM
- More water is reabsorbed into the blood from the collecting duct (through additional aquaporins), decreasing the volume of urine and increasing water potential in the blood.
Define Glomerular Filtration Rate (GFR)
volume of fluid passing into nephron per minute
(Healthy levels between 90-120 cm^3 min^-1)
What are the two treatments of kidney failure
-Heamodialysis
-Transplant
Describe Haemodialysis including pros and cons
-Blood circulates in machine
-dialysing fluid has correct amount of glucose, amino acids etc
-counter current flow
Pros: -no risk of rejection
-less ethical aversion
Cons: -take blood thinners
- very disruptive (multiple times a week)
What are the pros and cons of a kidney transplant?
Pros:
- less time-consuming
-less cost to NHS
-continuous effect rather than batch treatment
-don’t need to take blood thinners
Cons:
-invasive surgery -> risks
-organ rejection
-have to take immunosuppressants
How do you test for pregnancy?
MAbs in pregnancy tests:
-Urine onto test stick
-hCG binds to mobile antibodies attached to blue beads
-mobile antibodies move down test strip
-If hCG is present, it binds to fixed antibodies holding bead in place- blue line forms
-mobile antibodies w no hCG bind to different site that produces control line
How do you test for anabolic steroids?
urine sample gas chromatography
