B12 Excretion in Humans T16 Flashcards
Define excretion
removal of waste products and toxic substances from the body
3 human organs of excretion
- lungs
- skin
- kidneys
What do organs excrete?
- Lungs - carbon dioxide
- skin - excess water and salts -> sweat
- kidneys - excess water, urea and ions and salts
How and where is urea produced?
It’s formed in the ____ from the breakdown of unecessary ____________ in the body. It travels in the ____ and is removed by the kidneys
- liver
- amino acids
- blood
How and where is urea produced?
It is produced by respiring ____ and is transported by the ____ to the lungs where it’s excreted.
- tissues
- blood
structure of urinary system
● The inner part of the kidney is called the medulla and the outer part is called the cortex.
● The ureter carries from kidneys to the bladder to be excreted out the body.
● The kidney is supplied by the renal artery and a renal vein takes blood away.
● Each kidney contains millions of kidney tubules or nephrons
Order of the urinary system
- kidney
- ureter
- bladder
- urethra
Describe the structure of the urinary system
- The inner part of the kidney is called the medulla and the outer part is called the cortex.
- The ureter carries from kidneys to the bladder to be excreted out the body.
- The kidney is supplied by the renal artery and a renal vein takes blood away.
- Each kidney contains millions of kidney tubules or nephrons
renal artery
oxygenated blood to the kidney
renal vein
deoxygenated blood out of the kidney
ureter
takes urine from kidneys to bladder
urethra
tube that carries urine out the body during urination
What do the kidneys do?
filters blood
makes urine
Urine
watste product of kidney
contains:
1. excess water
2. urea
3. ions (salts)
What 3 functions does the nephron do?
- ultrafiltration
- selective reabsorption
- osmoregualtion
Order of nephron
- glomerulus
- Bowman’s capsule
- first convoluted tubule
- goes through cortex to medulla
- loop of Henle
- out of medulla into cortex
- second convoluted tubule
- collecting duct
- ureter
Describe the process of ultrafiltration in the glomerulus
- renal artery transports oxygenated blood under high pressure to glomerulus through arterioles
- fluid (filtrate) from blood forced through walls of capillaries into Bowman’s capsule
3.
Why is there a wider dimater of the arteriole entering the golmerulus, compared to the arteriole leaving
to produces a high pressure in the glomerulus -> forces the fluid from blood into the capillaries of Bowman’s capsule
ULTRAFILTRATION -> water, salts, glucose, urea
what is ADH and what does it do
released into the pancreas by the pituitary gland when a receptor in the brain detects that the blood is too concentrated
● It travels in the bloodstream to the kidney tubules
● An increased amount of ADH reaching the tubules increases their permeability to water,
so more moves out of the tubule and back into the bloodstream
● This results in a smaller volume of more concentrated (yellow) urine and the blood becoming less concentrated as more water moves into it
little water in blood - adh released, more water absorbed by kidneys, less water lost in urine, blood water returns to normal level
too mcuh water in blood - adh released, less water absorbed by kidneys, more water lost in urine, blood water returns to normal level
on a hot day, explain levels of sweat and urine
lots of sweat - leads to dehydration, leads to salt loss, so kidneys make up for it by increasing how much salt the body keeps - makes us thirsty and drink more
barely any urine
explain why protein and glucose are found in blood plasma but not in urine
protein - too large to pass through filter, not absorbed
glucose - passes through kidney filter and is reabsrobed
