Love your kidneys Flashcards
What is included in the urinary system
kidneys, ureters, bladder, urethra
Summary of renal functions
- Regulation of ECF volume and composition
- Elimination of endogenous waste products
- Kidneys eliminate foreign substances
- Kidneys have endocrine functions
What is the most important function of the kidney
homeostatic maintenance of ECF volume and composition
Why is water balance crucial
It is the solvent of ICF and ECF
What else does the kidney regulate
The electrolyte composition of the ECF
Failure to eliminate waste products
Can cause serious disease and even death if no interventions are made
kidneys eliminate foreign substances
Such as:
- drugs
- food additives
- pesticides
Erythropoietin (EPO)
Acts on bone marrow to enhance the synthesis of red blood cells
Renin
substance involved in the autoregulation of the kidney
What is the superiour surface of the kidney capped by
adrenal gland
What is the basic unit of the kidney
nephron
How many nephrons are in 2 kidneys
2.5 million
What % of total cardiac output do they kidneys receive
20-25%
Roughly how much blood flows through kidneys each minute
1200ml
How do they kidneys receive blood
renal artery
basic renal processes
- Filtration
- reabsorption
- secretion
Filtration
The formation of glomerular capillaries of an essentially protein-free filtrate of plasma
What allows pressure for filtration
blood pressure
Glomerular filtration rate (GFR)
very high (180L/day)
Reabsorption
Substances that the body wants are reabsorbed
- those that it doesnt, stay in the tubule and are excreted
Secretion
Substances may be specifically removed from the body in this way
Which substance is actually being regulated
The ECF is being regulated and not the urine
What maintains pressure to allow filtration
Capsule
What level of Mbp does filtration completely halt
40mmHg
Autoregulation
Independent of nerves or hormones
- occurs in denervated and in isolated perfused kidneys
Autoregulation range
60-130mmHg
What can override autoregulation
Activation of sympathetic nerves and Angiotensin II
Peritubular capillaries
Responsible for reabsorption
What is a major site of reabsorption
proximal tubule
how is the proximal tubule left after reabsorption
isosmotic with plasma
What do all nephrons have in the cortex
proximal and distal tubules
system essential for water balance
the loops of Henle of juxtamedullary nephrons
the loops of Henle of juxtamedullary nephrons
Allows the kidney to make urine in times of water defecit q
Maximum concentration of urine that can be produced by the kidney
1200-1400 Osmoles/L
Minimum obligitary loss of water
0.5L/day
Kidneys producing urine of varying concentration
Becuase loops of henle of juxtamedullary nephrons act as concurrent multipliers
Ascending limb of the loop and Henle
- impermeable to water
- Actively co-transports Na+ and Cl- ions out of tubule lumen into the interstitium
Descending limb of the loop of Henle
frrly permeable to water, but relatively impermeable to NaCl
Significance of the concurrent multiplier
creates a hypertonic gradient in the medullary interstitium and delivers hypotonic fluid to the distal tubule
Site of water regulation
collecting duct
Collecting duct permeabiity
controlled by ADH
How does ADH affect collecting duct permebility
If ADH is present then water can leave the collecting duct
If maximum ADH is present
contents equilibrate with that of the medullary interstitium via osmotic efflux of water - becomes highly concentrated at the tip of the medulla
absence of ADH
Collecting ducts are impermeable to water - large volume of dilute urine is excreted
