Chapter Seven Flashcards
The excretory system removes waste products
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
Renal vein
Carries filtered blood away from the kidneys
Renal tubule
Each of the long, fine, convoluted tubules conveying urine from the glomeruli to the renal pelvis in the vertebrate kidney
Kidney stones
- Formed from solid crystals that build up inside the kidneys, usually when urine is too concentrated
- Small crystals may pass through but they may combine to form larger stones that can get stuck in the ureter, urethra or bladder and may have to be removed by soundwaves or physically during surgery
Kidney failure
- Most kidney diseases effect the glomerulus and its efficiency of filtering blood
- Proteins and sometimes RBCs may leave the blood in the glomerulus and it will be present in the urine, if excessive proteins are lost in the urine blood protein levels fall and fluid accumulates in the tissues causing swelling.
- Lose the ability to excrete waste and control fluid level in the body
- Diabetes, high blood pressure and kidney diseases slowly destroy the nephrons in the kidneys
- Eventually the only way to maintain life is by dialysis or kidney transplantation
Lifestyle measures to maintain healthy kidneys
- Maintain healthy weight and diet
- Don’t smoke
- Drink water instead of sugary drinks
- Drink alcohol in moderate amounts
- Don’t use performance enhancing drugs
Cortex
Outer part of the kidney
Medulla
Inner part of kindey
Kidney structure
- Renal column
- Renal pyramid
- Renal pelvis > funnels urine into ureter
- Renal vein
- Renal artery
- Ureter
Peritoneal dialysis
- Occurs inside the body using the peritoneum as a membrane across in which waste can be removed
Peritoneum
Smooth tissue that lines the abdominal cavity and surrounds the abdominal organs
Haemodialysis
The passing of the blood through an artificial kidney or dialysis machine
Liver disease
- Unable to process toxins for elimination
- Causes > infection, autoimmune problems, genetic disorders, cancer and lifestyle factors such as excessive alcohol consumption and a fatty diet
- Symptoms > yellow skin and eyes, abdominal pain, swelling, nausea, fatigue, dark urine and faeces that are dark or pale coloured
Renal papilla
The component of the kidney from where the urine is secreted towards a minor calyx coming from the renal pyramid.
Renal calyces
- Singularly > calyx
- Part of the renal pelvis, a convex system of sinuses that connect the innermost part of the kidney to the ureters and, from there, to the bladder.
Renal
Relating to kidneys
Abdominal cavity
The cavity within the abdomen between the abdominal wall and the spine
Metabolic waste
Substances left over from metabolic processes which cannot be used by the organism and must therefore be excreted
Micturition
The action of urinating
Sweat gland
A small gland that secreted sweat situated in the dermis of the skin
Toxic
Poisonous
Urethra
The duct by which urine is conveyed out of the body from the bladder
Urinary bladder
The muscular sac in the pelvis just above and behind the pubic bone
Glycogen
A substance deposited in bodily tissues as a store of carbohydrates
Respiration
The action of breathing
Urea
A colourless crystalline compound which is the main nitrogenous breakdown product of protein metabolism and is excreted in urine.
Peritubular capillary network
Tiny blood vessels supplied by the efferent arteriole, that travel alongside nephrons allowing reabsorption and secretion between blood and the inner lumen of the nephron
Liver function
- Prepare materials for excretion
- Detoxifies alcohol
- Deactivates hormones
- Breaks down haemoglobin to produce bile pigments
Skin function
- Provide protective covering the surface of the body
- Maintain temperature of body
