Kidneys Flashcards
Define negative feedback
A receptor monitors the conditions and provides input to the coordinator which evaluates the information and provides an output to an effector which makes a response designed to take away the deviation/restore the set point
Define osmoregulation
The control of the water content and solute composition of body fluids (water potential)
Define excretion
The elimination of waste products of metabolism from an organism (e.g. urea and carbon dioxide)
Define counter-current multiplier
As more salt is pumped out on its journey up the ascending limb, the concentration of salt drops and the osmolarity decreases in strength
Describe the three layers of filtration in ultrafiltration
1) fenestrae (pores in the capillary cell wall)
2) basement membrane (smallest gaps, glycoproteins + collagen)
3) filtration slits in podocytes formed by processes called pedicels
Describe the process of selective reabsorption
1) sodium is pumped out of the PCT into the tissue fluid then peritubular capillary
2) decreased sodium concentration in the PCT cell
3) sodium and glucose are cotransported from the PCT lumen into the PCT cell
4) glucose diffuses across the cell
5) glucose go from the PCT cell into the tissue fluid then peritubular capillary by facilitated diffusion
6) glucose concentration gradient is maintained by circulation
Describe the process of reabsorption of water in the ascending limb of the loop of Henle
sodium and chloride are pumped into the tissue fluid of the medulla from the filtrate, decreasing the TFs water potential and increasing the salt concentration. This increases water potential in the filtrate.
Limb is impermeable to water so it cannot enter or leave
Describe the process of reabsorption of water in the descending limb of the loop of Henle
It’s permeable to water so water leaves the filtrate and enters the TF of the medulla by osmosis as the TF has a lower water potential due to the high salt concentration.
Further down the limb, water potential of the filtrate decreases, and salt and urea concentration increases due to the decrease in volume of water
State the hormone responsible for osmoregulation
Anti-diuretic hormone (ADH)
Where is ADH made? Stored? Secreted?
Made: hypothalamus
Stored: Posterior pituitary gland
Secreted: PPG
Suggest 5 treatments for kidney failure
1) reduced protein intake: less urea formed
2) medication to control K and Ca levels: high K results in heart arrythmia, high Ca increases risk of heart disease and osteoporosis
3) medication to reduced blood pressure: Ca channel blockers which dilate blood vessels, and beta blockers which reduced the effects of adrenaline (increased blood pressure)
4) transplant
5) Dialysis: haemodialysis, continuous ambulatory peritoneal dialysis
Define dialysis
The separation of large non-diffusible molecules from smaller diffusible molecules through a selectively permeable membrane
What is added to patient’s blood to prevent clotting
Heparin
