Please enable JavaScript.

Coggle requires JavaScript to display documents.

Excretion in Humans, cortex, medulla, processes occurring - Coggle Diagram

- - - - renal artery
        
        afferent arteriole
        
        glomerulus
        
        efferent arteriole
        
        venule
        
        renal vein
        
        ultrafiltration
        
        difference in diameter between afferent and efferent arterioles causes high hydrostatic pressure / blood pressure in glomerulus --> forces water and small molecules (glucose, amino acids, mineral salts, nitrogenous waste products) out of glomerulus through basement membrane (partially permeable membrane that wraps around glomerulus) and into the Bowman's capsule as the filtrate
        
        blood cells, platelets and large molecules (proteins, fats) remain in the glomerulus
    - - basement membrane
        
        proximal convoluted tubule
        
        loop of Henle
        
        distal convoluted tubule
        
        collecting duct
        
        excess water, mineral salts and metabolic waste products (urea, uric acid, creatinine) [urine] are passed out into renal pelvis
        
        selective reabsorption
        
        most water
        
        most mineral salts
        
        all glucose and amino acids
        
        some water
        
        some water
        
        some mineral salts
        
        some water
  - - - hypothalamus stimulated
        
        pituitary gland stimulated to release more ADH into bloodstream
        
        cells in walls of collecting duct become more permeable to water
        
        more water reabsorbed into blood plasma in capillaries
        
        smaller volume of urine
        
        urine is less diluted, more concentrated
        
        w.p. of blood plasma increases back to norm
    - - hypothalamus stimulated
        
        pituitary gland stimulated to release less ADH into bloodstream
        
        cells in walls of collecting duct become less permeable to water
        
        less water reabsorbed into blood plasma in capillaries
        
        larger volume of urine
        
        urine is more diluted, less concentrated
        
        w.p. of blood plasma decreases back to norm
  - - - Blood is drawn from vein in arm and is pumped through tubing in dialysis machine.
        
        Dialysis tubing is bathed in dialysis fluid; walls of tubing are partially permeable.
        
        Metabolic waste products diffuse out of dialysis tubing into dialysis fluid in dialysis machine. Blood cells, platelets and large molecules remain in tubing.
        
        Filtered blood is returned to vein in arm.
      - features
        
        dialysis fluid contains same concentration of essential substances as healthy blood
        
        ensures that essential substances do not diffuse out of blood and into dialysis fluid; if blood lacks essential substances, substances will diffuse from dialysis fluid into blood
        
        dialysis fluid does not contain metabolic waste products
        
        sets up concentration gradient for waste products to diffuse out of blood into dialysis fluid --> waste products are removed from blood
        
        dialysis tubing is narrow, long and coiled
        
        increases surface area to volume ratio --> speeds up rate of exchange of substances between blood and dialysis fluid / diffusion of waste products out of blood
        
        direction of blood flow is opposite to flow of dialysis fluid
        
        maintains concentration gradient for removal of waste products