Excretory System Flashcards
main functions of the kidney (6)
- Ion balance – especially Na+ and K+
- Osmotic balance – determine volume of urine produced
- Blood pressure – controls blood volume and ECF volume (extra cellular fluid)
- pH balance – retains or excretes H+ or HCO3
- Excretion – of nitrogenous wastes or other hydrophilic toxins
- Hormone production
kidney anatomy
- Renal cortex (more on the outside)
- Renal medulla (more inside)
- Pelvis inside
where does blood enter the kidneys
renal artery
bowmans capsule
Mouth of the tubules, cuplike expansion surrounding the glomerulus
nephrons
- Perform primary task of removing waste products
- Composed of two elements: Glomerulus, Renal tubule
glomerulus (nephrons)
twisted ball of capillaries (small blood vessels), delivers to the tubule
renal tubule (nephrons)
composed of single layer of cells
what do hormones and neurotransmitters do in the excretory system
ensure urine composition and the release of the urine matched to the physiological needs of the animal
what are the four processes involved in urine formation
filtration, reabsorption, secretion, excretion
filtration (in the glomerulus)
- As blood flows into each nephron, it enters a cluster of tiny blood vessels – the glomerulus
- thin walls of glomerulus allow smaller molecules, wastes, and fluids to pass into the tubule
- larger molecules, such as proteins and blood cells stay in the blood vessel
reabsorption (PCT, DCT, collecting duct)
- Recovery from substances from the lumen of the tubule
- Most molecules are reabsorbed through a combination of facilitated diffusion and active transport
secretion (loop of henle, dct, collecting duct)
- Transfer of solutes from the blood into the tubule lumen
- Uses transporters found in the cells that line the lumen
- Most important secretory products are K+, NH4+, and H+
how much urea is in final urine vs. primary urine
primary: 0.03 final: 2.00
how much salt is in final urine vs. primary urine
primary: 0.72 final: 1.50
what are the main hormones involved in the excretory system
ADH (antidiuretic hormone), Aldosterone
