Chapter Seven Flashcards
The excretory system removes waste products (52 cards)
Excretion
The process of the removal of waste products of metabolism
Different forms of excretion in the body
- Lungs > CO2
- Skin > water, salts, urea, lactic acid
- Alimentary canal > bile pigments
- Kidneys > urea, uric acid
Deamination
The process of the formation of urea in the liver
Liver in excretion
- Excess proteins are broken down into amino acids
- Amino acids are broken down further into ammonia and carbohydrates
- Amino acid + oxygen = ammonia and carbohydrate
- Ammonia is extremely soluble in water but in large amounts is toxic to the cells so the liver quickly converts it to urea
Urea creation equation
Energy + CO2 + ammonia = urea water
Kidneys function
- Rid the body of wastes (especially nitrogenous wastes such as urea)
- Regulates the balance of fluid, salt and pH
Nephron
- Functional unit of the kidneys
- Each kidney has roughly one million nephrons
Nephrons contain
- Glomerular capsule
- Renal tubule and their associated blood supply
Glomerular filtration
- Filtration takes place in the renal corpuscle
- The renal corpuscle consists of Glomerular capsule and a mass of blood capillaries- the glomerulus
Filtration (blood to nephron)
- As the blood enters the glomerulus the fluid is forced out of the capillaries due to high pressure
- Water and dissolved components are forced through the differentially permeable membrane into the capsule
- The fluid is called the filtrate
- Renal corpuscle > filtrate (water, urea, glucose, amino acids, vitamins + salts) > passive diffusion
Filtrate
- Consists of all the materials in the blood except for the red and white blood cells
- With one million nephrons in each kidney the amount of blood able to be filtered is extremely high
- Up to 180L of filtrate each day but only 1% is reabsorbed
Reabsorption (nephron to blood)
- Throughout the tubule many materials are removed from the filtrate and reabsorbed, including water, glucose and amino acids
- For effective reabsorption large SA is needed > long tubules and huge number of tubules
Proximal convoluted tubule reabsorption
- Closest tubule
- Water 60-70% (passive)
- Salts 60-70%, glucose 100%, amino acids 100% and vitamins 100% (active)
Loop of henle reabsorption
- Water 25% (passive)
- Na+/Cl- 25% (active)
Distal convoluted tubule reabsorption
Water 5% and Na+/Cl- 5% (active)
Collecting duct reabsorption
Water 5% (active)
Tubular secretion (blood to nephron)
- Adds material to the filtrate from the blood as the filtrate travels along the tubule
- The filtrate from this now enters the renal pelvis and is called urine
Urine
- Collected in the bladder and is eliminated through the urethra
- Average amount of urine eliminated in 24hrs is 1.5L
Urine contains
- 96% water
- 2% urea
- 1.5% other various ions
- 0.5% other products
Structure of the excretory system
- Kidneys
- Ureters
- Bladder
- Liver
- Urethra
Afferent arteriole
The arteriole going in to the glomerular capsule
Efferent arteriole
The arteriole going away from the glomerular capsule
Ureter
The duct by which urine passes from the kidney to the bladder
Renal artery
Brings blood to the kidneys for filtration