Excretory system Flashcards
Excretion
Removal of metabolic cell waste
Examples of cell waste
water, urea, lactic
Excretory system consists of:
Kidneys (filter blood and remove wastes), lungs (removes CO2 and water), skin (sweat glands remove water, urea, lactic acid and salts), liver (accessory, undergoes deamination)
Deamination
Break down of amino acids into urea
Urinary system consists of:
2 kidneys, 2 ureters, 1 urinary bladder and 1 urethra
What does the urinary system do
filters the blood and removes waste products via urine produced in the kidneys which travels down the ureters into the bladder
Urination
removal of waste from kidney to the bladder
Micturition
Movement of urine from the bladder to the urethra to out of the body
How do the kidneys get blood
Renal arteries carry blood to the kidneys, renal veins carry blood away to join the IVC
A nephron consists of:
renal corpuscle made of the glomerular/Browmans capsule, glomerulus (network of capillaries), various tubules and a network of capillaries
Function of the nephron
Filters the blood and forms urine
Afferent arteriole
enters the glomerular/Bowmans capsule which then separates into many capillaries
Efferent arteriole
exits the glomerular/Bowmans capsule
Basic steps of urine production
Filtration (removal of small molecules), reabsorption (required molecules moved back into the blood), secretion (unwanted molecules moved into filtrate)
How is blood separated from the glomerular capsule
2 layers of cells, 1 layer lining the glomerular capsule and 1 layer in the capillaries which allow for dissolved blood components to filter through the cell layer
What causes high pressure in the glomerular capsule and why is it needed
High pressure is caused as the afferent artery is larger than the efferent artery which then forces substances through the permeable membrane and the capsule
Filtrate contains
water, salt, amino acids, fatty acids, glucose, urea, uric acid, creatine, hormones, toxins and ions
What stays in the capillary in glomerular filtration
Blood cells and plasma proteins
Why is selective reabsorption needed
small molecules get pushed out due to the high pressure but are needed for body functions so must move back into the blood capillaries
Where does selective reabsorption occur
proximal convoluted tubule, distal convoluted tubule, loop of Henle and collecting ducts
What is reabsorbed in the proximal convoluted tubule
most glucose, aa, vitamins, urea, Na, Cl, K, Ca ions, some drugs and some water (passive)
What is reabsorbed in the distal convoluted tubule
some Na, Cl ions, some drugs, active reabsorption of water depending on the bodies needs
What is reabsorbed in the loop of Henle
passive reabsorption of water, some Na, Cl, K ions
What is reabsorbed in the collecting ducts
active reabsorption of water depending on the bodies needs
Why is secretion needed
Materials not filtered into the tubule at the glomerulus need to be removed from the blood into the tubule
Where does secretion mainly occur
Distal convoluted tubule
What is secreted during secretion
potassium and hydrogen ions and drugs such as penicillin and creatine, can be active or passive
What happens to molecules not reabsorbed into the blood
drains into collecting ducts into the renal pelvis to form urine
