5.1.2 The Kidney Flashcards
Where is the kidney found
What is jt surrounded by
Attached to the back of the abdominal cavity
A layer of fat and fibrous connective tissue
What two processes is the kidney involved in
Excretion and osmoregulation
Explain the difference between the cortex and the medulla
Cortex= dark outer layer, dense capillary network and blood filtering takes place here
Medulla= lighter in colour contains the nephrons and collecting ducts
How many nephrons in each kidney
1 million
What is the glomerulus
A fine network of capillaries which increases blood pressure to push fluid out
What is selective reabsorption
When useful substances are reabsorbed back into the blood and excretory products remain in nephron
Where does ultrafiltration take place
In the bowmans capsule
How is tissue fluid formed
High hyrdrostatic pressure forces fluid out of the capillary into the tissue
Moves back into the blood when low hydrostatic pressure is formed at the venous end of the capillary
Describe the process of ultrafiltration at the glomerulus
Blood enters afferent arteriole (large diameter) under high pressure
The efferent arteriole has a smaller diameter, this increases bloods hydrostatic pressure in glomerulus
Hydrostatic pressure In glomerulus bigger than bowmans capsule, Fluid is forced out into bowmans capsule
Basement membrane: stops erythrocytes and large molecules from passing through
Fenestrations: in squamous endothelial cells of capillary allow small substances through (not RBC)
Podocyte cells: extensions called pedicels prevent large plasma proteins and platelets from passing through
How are podocytes adapted
Have extensions called pedicels (aka major processes) have gaps to allow specific molecules through
How does high blood pressure damage capillaries
Allows proteins and sometimes RBC to enter the filtrate
how is ultrafiltration similar and different to tissue fluid formation
similarities- both occur in the capillary, large molecules remain in the capillary, molecules are reabsorbed
differences- filtrate enters PCT, filtrate bathes tissues and cells
molecules that are not reabsorbed form urine, molecules that are not reabsorbed form lymph
why must glucose be reabsorbed back into the blood
to be used in aerobic respiration
where and what is reabsorbed
in the PCT
glucose, amino acids, vitamins and hormones
what percentage of fluid is reabsorbed
85%
what type of cells make the PCT
cuboidal epithelial cells
what in the PCT increases SA
microvilli
describe the process of selective reabsorption
1) na+ and glucose enter the PCT through co-transport proteins
2) water potential of cell lowered so water enters cell by osmosis
3) 3 Na+ out and 2k+ in, glucose is facilitated diffusion into the blood
4) wp of blood lowered, water moves into blood
5) large molecules are removed by endocytosis
the deeper into the medulla you go….
the lower the WP
describe the UPPER part of the descending limb
it is impermeable to water but the lower part is permeable to water but impermeable to salts
describe the ascending limb of the loop of henle
permeable to salts but impermeable to water
describe the collecting duct
impermeable to salts but permeable to water
describe what processes occur in the descending limb
water is lost from fltrate by osmosis, goes into the blood
describe the processes in the ascending limb
bottom- salts diffuse out
upper- ions are actively transported out into the medulla
this gives a higher water potential to filtrate= more dilute
what processes happen in the DCT
sodium ions are reabsorbed and K+ and H+ ions are added into dct
what happens in the collecting duct
water is lost from filtrate by osmosis from collecting duct, as deeper into medulla= lower WP, some urea moves out as well.
what is the name for the term given when two limbs run close to each other in opposite direction
hair pin counter current multiplier
describe the loop of henle in desert animals
longer loop of henle
lowering medulla water potential
urine has a lower water potential and is more concentrated
what happens if the body lacks salt
sodium ions are actively transported out of the DCT with chloride ions
what happens in the DCT if ADH has been released
the walls of the dct also become more permeable to water and water leaves
what hormone regulates osmoregulation
where is it released from and where does it target
antidiuretic hormone
released from pituitary gland
targets collecting ducts
how does hypothalamus monitor water potential
osmoreceptors
what would happen if water potential was too low
water potential drops too low:
1) ADH is released from the posterioir pituitary cells when it is stimulated by osmoreceptors in the hypothalamus
2) ADH secreted into blood
3) binds to complimentary receptors on collecting duct
4) increases the number of aquaporins ( protein channels) in membrane. activates a series of reactions (via cAMP)= formation of vesicles with aquaporins to fuse with membrane
5) more aquaporins so more water moves by osmosis into the tissue fluid
what would happen when baroreceptors detect a rise in blood pressure, in terms of adh production
decreases, more water in blood would increase pressure further
why does kidney failure occur
glomeruli become inflamed and swollen due to:
- diabetes mellitus
- hypertension- damages structure of basement membrane
- infection- podocytes and tubules become damaged
- genetic conditions- kidney tissue has fluid filled cysts
what is found in the urine if the kidneys are infected
proteins and blood cells
what happens when kidneys fail
unable to remove excess ions, urea and water
what is used to measure kidney function, how do they do this
glomerular filtrate rate
a blood test measures levels of creatinine in the blood, if this increases it is a sign that kidneys are not functioning properly
evaluate using this blood test to measure glomerular filtrate rate
advantages:
produced at a constant rate per day
freely filtered at the glomerulus
disadvantages:
estimate
10% secreted by tubules
describe the process of renal dialysis
1) blood leaves the artery, a anticoagulant drug is given to prevent clots in the machine
2) blood passes in the oposite direction to maintain a conc gradient for diffusion, waste molecules diffuse across membrane, water by osmosis
3) air detector stops any air bubbles entering the persons blood ( could be fatal) , clean blood enters the vein
4) excess urea and mineral ions must leave the blood
5) anti coagulant drug stops to allow blood to clot normally
describe the process of peritoneal dialysis
where fluid of correct concentrations is pumped into abdomen wall, between the wall and peritoneum membrane (acts as a partially permeable membrane) waste materials move into dialysate
pro: can be done at home
evaluate kidney transplants
advantages:
no time consuming dialysis
no longer chronically ill
can travel
cons:
immunosuppressant drugs for life
major surgery
risk of infection
name the genetic marker on human tissue
what does this mean for transplants
human leukocyte antigen
should recieve a transplant from someone with an identical or similar HLA
what if present in urine is a symptom for: diabetes mellitus muscle damage pregnancy ovulation
glucose
creatine
human chorionic gonadotropin
luteinising hormone
what are monoclonal antibodies
antibodies that are from a single clone of cells that are produced to target particular cells or chemicals in the body
how are monoclonal antibodies for hcg produced
1) a mouse is injected with HCG to make the required antibody
2) B cells that make the required antibody are removed from mouse spleen
3) b cells are fused with myeloma cells which do not divide very rapidly
4) a hybridoma is formed, reproduces rapidly
5) each hybridoma produces the desired antibody, collected and purified for use
explain how a pregnancy testing kit detects the pregnancy hormone
1- testing for hcg
2- hormone is so small it passes from blood into filtrate
3) free monoclonal antibodies complimentary to hcg bind
4) other immobilised monoclonal antibodies in the test window bind to hcg stopping hcg and antibody with dye
5) more immobilised antibodies in the control window bind only to the antibody with the dye to show that the test is working
describe the process of random sampling to athletes for drugs
urine sample taken, vapourised with a gas solvent, passed into a gas chromatography machine, gas solvent dissolves the substance allowing a chromatogram to form
pros and cons of steroids
pros, can train for longer, respire for longer, build muscle quicker
cons, depression, anger, liver damage, heart attacks
