renal physiology 1 Flashcards
what are the functions of the kidney
endocrine function, maintain balance of salt, water and pH, excrete waste products
what is the cardiac output, renal blood flow, urine flow
- Cardiac output = 5L/min
- Renal blood flow = 1L/min
- Urine flow = 1 ml/min
describe the renal blood supply
Renal artery ↓ Interlobar artery ↓ Arcuate artery ↓ Interlobular artery ↓ Afferent arteriole ↓ (Nephron) Glomerular Capillary Peritubular Capillary
where are the nephrons 2 capillary beds
glomerulus
peritubular area
what are the 2 sets of capillaries in the kidneys connected by
efferent arteriole
what is the renal corpuscle formed of
the glomerular tuft and the Bowman’s capsule
what do the peritubular capillaries join to form?
veins
what is the entire capillary covered in
podocytes
what percentage of the plasma flowing through the glomerulus filters into the bowman’s capsule
20%
what happens in the bowman’s space?
• The filtrate from the glomerulus collects in Bowman’s space before flowing into the proximal convoluted tubule
what part of the nephron is responsible for secretion and reabsorption
distal (tubule)
what are the 3 layers of the filtration barrier?
- Single-celled capillary endothelium
- Basement membrane (basal lamina)
- Single-celled epithelium lining of bowman’s capsule (podocytes with foot processes)
what molecules can pass through the filtration barrier ?
- Small molecules and ions up to 10kDa can pass freely e.g. glucose, uric acid, potassium, creatinine
- Larger molecules increasingly restricted
- Fixed negative charge in glomerular basement membrane repels negatively charged anions
what does crossing the filtration barrier depend upon?
• Pressure
o HYDROSTATIC PRESSURE constant along length of capillary
o OSMOTIC PRESSURE rises along length of capillary
• Size of the molecule
• Charge of the molecule
• Rate of blood flow
• Binding to plasma proteins e.g. calcium, hormones such as thyroxine
what do efferent arterioles do?
carry blood away from glomerulus then supply peritubular capillaries which supply proximal and distal convoluted tubules - also supply vasa recti which supplies the loop of Henle
• Both peritubular capillaries & vasa recti supply: water and solutes to be secreted into filtrate & blood to carry away water and solutes reabsorbed by the kidneys