Excretory System Flashcards
What does homeostasis mean?
- The maintenance of constant internal environment
What is the functions of the excretory system?
- Filtering blood
- Regulating body fluids
- Removing nitrogenous waste
- Maintaining homeostasis
What is the functions of the kidney?
- Formation of urine
- Production of renin (enzyme)
- Conversion of vitamin D to its active form
- Production of erythropoietin
What is a nephron?
- Within the kidney there are filtering units called nephrons
What are the functions of nephrons?
- Nephrons are supplied with blood by the renal artery, they filter blood to produce urine
- Nephrons ensure waste is excreted, whilst some substances are reabsorbed back into the blood
What are the processes in the nephron?
- Ultrafiltration (removing substances from the blood)
- Selective reabsorption (reabsorbing the substance the body needs)
- Urine formation (substances which are not reabsorbed travel as urine along the nephron to the collection ducts where waste goes to the bladder
What is osmoregulation?
- The balancing of the salt and water concentration in the body
What is the importance of osmoregulation?
- Keeps the cells working
- The concentrations of solutes surrounding cells become too high (hypertonic)➡️cells shrivel
- The concentrations of solutes surrounding cells become too low (hypotonic) ➡️take too much water and burst
What is the mechanism of osmoregulation?
- Physiology process to maintain water balance
- Uses osmoreceptors and endocrine system
- Hypothalamus detects a change in water content via osmoreceptors, initiates response
What happens when there is a high water content?
1.Body=hydrate
2. Osmoreceptors send response to pituitary gland
3. ADH (anti-diuretic hormone) is decreased
4. Less water is absorbed by kidneys
5. More urine produced to lose water
What happens when there is a low water content?
- Body=dehydrated
- Osmoreceptors send response to pituitary gland
- ADH (anti-diuretic hormone) is increased=more water reabsorbed by kidney via osmosis
- Less urine produced
Compare the removal of nitrogenous waste in birds and mammals
- Mammals - produce urine, excrete urine and faeces separately , remove ammonia as urea
- Birds- produce solid waste, urine and faeces are combined, remove ammonia as uric acid
State the hormone involved in osmoregulation
- ADH (antidiuretic hormone)
Describe two roles of the loop of henle
- Conducts urine along a u-shaped portion of the tubule in a nephron
- Reabsorbs water - prevents dehydration- in the descending limb
- Reabsorbs ions into the bloodstream
Explain two functions of the excretory system
- Filtering blood- to remove toxic waste products
- Maintaining homeostasis- by maintaining salt and water levels
- Removing nitrogenous waste - formation of urine