What is the location of the kidneys?
- one on each side
- posterior to abdominal wall
- high up under diaphragm
- retroperitoneal
What encapsulates the kidneys?
layers of fascia and fairly firm renal fat
What is the cortex of the kidney?
outer portion of the kidney
What is the medulla of the kidney?
the inner part of the kidney - split into renal pyramids
What transports urine to the bladder?
ureter
What is the functional unit of the kidney?
nephron - initial filtrate and final urine produced
What are the 5 parts of the nephron?
- glomerulus (renal corpuscle)
- proximal convoluted tubule (PCT)
- loop of Henlé (descending and ascending)
- distal convoluted tubule (DCT)
- collecting duct
look up image
(glomerulus - blood filtration part
renal tubule - filtrate recovery part)
What are the two types of nephron?
- juxtamedullary
- superficial
What are the features/function of the juxtamedullary nephrons?
- concentrate urine
- glomeruli in inner cortical regions - long nephron loops
- deeper in medulla of kidney
- associated with vascular structure - vasa recta
- receive about 10% of renal supply
What are the features/function of the superficial nephrons?
- reabsorb large % of fluid that filters from vasculature
- glomeruli in outer cortical regions - short nephron loops
- sit more superficially
- receive about 90% of renal supply
What is the location of the ureter in females?
- passes posterior to ovary
- passes lateral to cervix and vagina
(into bladder)
What is the location the urethra in males?
- passes through prostate and into panic (from bladder)
What are the walls of the ureters and bladder made of?
- muscular walls - smooth and involuntary
- transitional endothelium to allow distension (rounded and piled on top of each other - flatten and spread out to cope with distension)
What controls the bladder?
Detrusor muscle
- fills by relaxation of muscular wall
- empty by muscular contraction - aided by raised inna-abdominal pressure
- muscle is smooth and involuntary
but,
- external sphincter around urethra is stated and under voluntary control
What are the functions of the kidney?
- excretory
- cleanses blood of metabolic end products, toxins, water, ions - that may be surplus - maintains “homeostasis”
- also an endocrine and homeostatic organ - controls blood pressure, tissue osmolality, electrolyte levels
- monitor and affect acid/base balance
How does blood filtration occur in the kidney?
blood is forced under pressure through a glomerular filtration barrier to separate plasma from cells and proteins
How do the kidneys maintain blood/body homeostasis?
via production of urine - ie. removal of excess water, electrolytes, toxic metabolic waste (urea, creatinine) from circulating blood
How do the kidneys monitor and affectacid/base balance?
- excrete hydrogen ions during acidosis or
- bicarbonate ions during alkalosis
Why do the kidneys secrete renin?
- indirectly raises blood pressure
Why do kidneys secrete erythropoietin?
- accelerates red blood cell production
What conducts urine from the kidneys to the bladder?
ureters
What is used for the passage of urine out of the body?
urethra
What is reabsorption?
the process that moves solutes and water out of the filtrate and back into your bloodstream
(reabsorbed - because they were already absorbed in the digestive tract after a meal)
What are the steps of reabsorption?
- passive or active movement of water and dissolved substances from the fluid inside the tubule through the tubule wall into the space outside
- then, water and these substances move through the capillary walls back into the bloodstream either by passive or active transport
- (channels and transporters aid the passage)
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