Renal System Flashcards
What is the anatomical position of kidneys?
Posterior of abdominal wall inferior to diaphragm and posterior to peritoneum, superior to kidneys is the adrenal glands (which secrete hormones eg cortisol, adrenaline, aldosterone.) to regulate metabolism.
What is the structure of kidney on a large scale
The outer fibrous layer is the capsule
Then cortex the middle layer
Innermost layer is the medulla contains renal pyramids and calyces forming drainage system. 7rine is formed in the pyramids and pass through the papilla.
What is the process of filtration? (Glomerulus)
Blood travels from aorta to renal artery to tuft of capillaries (glomerulus), as the walls are semi permeable pressure goes from lower (in afferent arteriole) to higher (in efferent arteriole) . Semi permeable membrane allows big molecules like rbc to pass and small ones like water/ions/salt.
How do kidneys regulate pressure?
Through autoregulation, the muscle in blood vessel walls contract and relax to keep optimum blood pressure for glomerular filtration.
What happens at the proximal convoluted tubule PCT?
Components filtered out (eg urea) and main things are reabsorbed eg glucose electrolytes water amino acids, ions. Isotonic
Loop of Henle: further reabsorption takes place mainly water, sodium, and chloride absorbed here.
All done via active transport of ions
What happens at the distal convoluted tubule DCT?
Further reabsorption mainly of electrolytes eg sodium. Hypotonic, so influx into the DCT.
Products like amino acids are totally reabsorbed or glucose (unless above 9mmol/L as it would have reached a threshold maximum.
What happens at the collecting duct
Collecting duct can absorb water dependant on hydration of body, once filtrate enters collecting duct it becomes urine and travels to papilla of pyramid and continues journey to calyxes and renal pelvis.
What is the role of ADH and how does it affect volume of urine?
Anti-diuretic hormone (ADH) is released via osmoreceptors in the hypothalamus that detect water volume in the blood is low pituitary gland stimulated to release ADH. This travels via blood to collecting duct and cause the membrane of collecting duct to release aqua poring that cause the membrane to become more permeable allowing water to move back into the blood releasing, a more concentrated less volume of urine and vice versa for if body was dehydrated.
What is the role of ANP in increasing fluid lost?
Atrial natriuretic peptide (ANP) if blood volume is increased strech receptors in atria of heart notice and cause cardiac muscle cells to release ANP this reduces reabsorption of sodium and water in PCT and collecting ducts, allows more of it to turn into urine.
Function of ureter
Carry urine from kidneys to bladder, hollow muscular tubes continuous with the funnel shaped renal pelvis above. As urine accumulates pressure in bladder arises and ureters are compressed. Closes openings to prevent backflow from bladder into ureters.
Size and position varies dependant on volume of urine
Function of bladder
Three layers
Outer layer: connective tissue, loose, contains blood and lymphatic vessels, upper surface covered by peritoneum.
Middle layer: smooth muscle fibres and elastic tissue, allows distension of bladder and when it contracts bladder empties.
Inner layer: the mucosa, so posed of transitional epithelium and permits distension of bladder as it fills. ( distension allows awareness of the need to pass urine
What is micturition and the purpose of it?
Micturition reflex initiated when accumulation of urine in bladder is transmitted to spinal cord then micturition centra in brain.
Stimulates involuntary contraction of deters or muscle and relaxation of internal urethral sphincter allowing expulsion of urine from the bladder
