excretory system Flashcards
what is excretion?
removal of metabolic wastes produced by chemical activities of an organisms cells
what are the excretory organs?
lungs, liver, sweat glands, kidneys, alimentary canal
why is excretion essential?
metabolic wastes are toxic and if left in the body they can cause sickness.
what is deamination and the word equation?
- removal of an amino group of a molecule
- the remaining part of the amino acid is converted to carbohydrate to release energy
- amino acid + oxygen > carbohydrate (energy) + ammonia (toxic)
what happens after deamination?
once the amino group is removed, it is converted by the liver cells to ammonia then to urea where it is eliminated in urine
describe the role of skin in excretion
removes excess water and salts via sweat glands.
what is a nephron?
- the filtering unit of the kidney, where urine is formed.
what is glomerular filtration?
- takes place in the renal corpuscle
- when fluid is forced out of the blood in the glomerulus due to blood pressure and is collected by the Bowman’s/glomerular capsule
what is filtrate?
- contains everything except blood cells and plasma proteins as they are too big
- contains = water, urea, salt, glucose, amino acids.
what is tubular secretion?
- adds materials to the filtrate from the blood like potassium, hydrogen ions and creatinine.
- the process maintains blood pH and urine pH
what are kidney stones and how are they formed?
- formed from solid crystals that build up inside the kidneys.
- usually form when urine becomes too concentrated - urine is too acidic or basic, too much oxalate in diet
- small crystals can pass unnoticed or crystals may form stones which can get stuck in ureter, bladder or urethra causing pain
what are the symptoms of kidney stones?
blood in urine, burning while urinating, nausea, extreme pain when the stone passes
what are the treatments for kidney stones?
laser pulses sound waves surgically removed medication increase water, activity, improve diet
what is kidney failure and the causes?
- kidneys lose ability to excrete waste and control the level of fluid in the body.
- high sugar and salt intake, lack of water, diabetes, high blood pressure
what are the treatments for kindey failure
- dialysis
transplant
what is liver disease and the causes?
- liver is not able to function effectively - it is unable to process toxins ready for elimination
- can be caused by infections, viruses, autoimmune problem
the function of the kidney?
- get rid of body wastes
- regulate the balance of fluid, salt + Ph in blood
what are the tubule pathways?
- Bowmans capsule
- proximal convoluted
- loop of henle
- DCT
- collecting duct
what are the tybule pathways?
- Bowmans capsule
- proximal convoluted
- loop of henle
- DCT
- collecting duct
what are the blood vessels pathway?
- renal artery
- afferent arterioles
- glomerulus
- effective arterioles
- network of capillary
- renal vein
describe the structure and function of a nephron
- Bowman capsule surrounds the glomerulus > collects fluid filtered out of capillary
- efferent arterioles has a smaller diameter than afferent arteriole > raise blood pressure = more fluid filtered out of the blood
- tubule has PCT + DCT + loop of henle > large SA for reabsorbtion + secretion
- each kidney has 1 million nephrons+ > total SA for reabsorbtion + secretion is extremely large
what are the 3 steps of urine formation?
glomerular filtration, selective reabsorbtion, tubular secretion
what is glomerular filtration?
blood > tubule
- occurs in renal corpuscle
- fluid is forced out of the blood and collected by Bowmans capsule
- 2 membranes (both 1 cell thick)
- high-pressure forces substances out of blood differentially permeable membranes into capsule = filtrate
- size determines what is filtered
- filtrate produced by renal capsule (only 1% leaves as urine = most is absorbed into blood)
what is selective reabsorption?
tubule > blood
- many of the components of the plasma that are filtered from the capillaries of the glomerulus of use to the body and their excretion would be undesirable
- occurs in PCT (renal tubule) > materials are reabsorbed from PCT into capillary network
- materials reabsorbed = amino acids, glucose, sodium, water ( active transport = except urea + wastes)
- Large SA required
what is tubular secretion?
blood/capillary network > tubule
- occurs in DCT
- materials are secreted into tubule from capillary
- materials secreted = excess H ions, ammonium ions, penicillin, the heroine
- effects = remove certain unwanted substances from body + maintain PH of blood
