4.5.3.3 Maintaining Water and Nitrogen Balance in the Body Flashcards
(25 cards)
What is osmoregulation
- control of water levels and mineral salts in blood
Why are water levels and mineral salts controlled?
- to protect cells
- by stopping to much water from entering or leaving them as concentration of both are the same inside and outside of cells
- won’t function effectively if too much is gained or lost
What happens if water concentration is too high outside?
- water enters cells by osmosis
- cells may burst
What happens if water concentration is too low outside?
- water will leave by osmosis
- cells may shrivel
How is osmoregulation similar in plants?
- full: cell walls are turgid/firm
- lose: become flaccid, cytoplasm shrinks away from cell wall
How are water, ions and urea lost in the body?
- urine from kidneys
- sweat from skin
- water vapour from lungs during exhalation?
How are water, ions and urea lost in the body by urine?
- kidneys are organs of urinary system
How are water, ions and urea lost in the body by sweat?
- sweat contains water, ions and urea
- when sweat is produced, they are lost
- cannot control levels lost
How are water, ions and urea lost in the body by exhalation?
- water leaves body during exhalation as well as carbon dioxide
- cannot controls levels lost
What does the digestion of excess proteins from the diet result in?
- excess amino acids
- need to excreted safely
What does the liver do with amino acids?
- deanimates them to form ammonia after being transported from small intestine
- urea is also produced
Why does ammonia need to excreted immediately?
- it is toxic so it needs to converted to urea
How is blood transported to the kidneys?
- through renal artery
How is blood transported back to the circulatory system?
- through renal vein
What is the function of kidneys in maintaining water balance of the body?
- they produce urine (which helps maintain the balance)
- urine contains water, urea and salts
What is urea?
- main waste product remove in urine as it is not reabsorbed in kidney
What is a nephron?
- filtering unit
- made of a tubule
- responsible for removing urea, excess water and mineral ions from blood
What are the different stages which a kidney goes through to produce urine?
- filtration
- selective reabsorption
- formation of urine
What happens during filtration?
- blood passed through nephron to inside kidneys
- blood under high pressure at start of nephron, aids ultrafiltration of blood
- small molecules (ureas, water, ions, glucose) filted out and into nephron tubule
- large molecules (proteins) too big to fit through capillary wall and stay in blood
What happens during selective reabsorption?
- kidneys reabsorb molecules which are needed, let the other pass out in urine
- all of glucose reabsorbed
- as much water as needed reabsorbed (balance of water level in plasma)
- as many ions as needed reabsorbed (balance of mineral ions in plasma)
What happens during the formation of urine?
- molecules which aren’t selectively reabsorbed continue along tubule as urine and pass down to bladder
Why is the hypothalamus important in water balance?
- detects changes in concentration in blood plasma
Why is the pituitary gland important in water balance?
- regulates release of anti-diuretic hormone (ADH)
What happens when the hypothalamus detects a high concentration of blood (less water)?
- pituitary gland releases more ADH
- ADH makes kidney tubules more permeable (more water can go through)
- more water is reabsorbed back into blood
- urine is more concentrated (less water in it)
