B12 - Homeostasis in action Flashcards
(27 cards)
How is body temperature monitored and controlled?
Thermoregulatory centre in the brain
How does the thermoregulatory centre work?(2)
- Contains receptors sensitive to the temperature of the blood
- Skin contains temperature receptors and sends nervous impulses to the thermoregulatory centre
What happens if body temperature is too high and what is the transfer of energy?(3)
- Vasodilation - Blood vessels dilate
- Sweat is produced from the sweat glands
- This causes a transfer of energy from the skin to the environment
What happens if body temperature is too low?(3)
- Vasoconstriction - Blood vessels constrict
- sweat stops
- skeletal muscles contract(shiver)
What happens to a cell if the surrounding fluid is too hypotonic(high water concentration)?
Cells will gain water and swell, potentially bursting
What happens to a cell if the surrounding fluid is too hypertonic(solute concentrated)?
Cells will lose water and shrivel, can disrupt cellular function and even lead to cell death
How is water lost from the body?(3)
- Water during exhalation by lungs
- Urine by kidneys
- Sweat by skin
How are ions and urea lost from the body?
Sweat and urine
How is excess water, ions and urea removed?
Via the kidneys in the urine
What happens if body cells lose or gain too much water by osmosis?
Do not function efficiently
What does the digestion of proteins from the diet result in?(3)
- Excess amino acids which need to be secreted safely
- In the liver these amino acids are deaminated to form ammonia
- Ammonia is toxic so it is converted to urea for safe excretion
What is the function of the kidneys to maintain water balance?(3)
Produce urine by
- filtration of the blood
- selective reabsorption of useful substances like glucose, some ions and water
What hormone controls water levels?
ADH
Where is ADH released from?
Pituitary gland
When is ADH released?
When blood is too concentrated
How does ADH affect the permeability of kidney tubules?(2)
- Causes kidney tubules to become more permeable
- Allows more water to be reabsorbed back into the blood during selective reabsorption
What is this process controlled by?
Negative feedback - aims to keep the concentration of the blood plasma constant
What happens to the urine if there is more ADH released(too little water)?
More concentrated
What happens to the urine if there is less ADH released(too much water)?
More dilute
How can kidney failure be treated?(2)
- Organ transplant
- Kidney dialysis
How does dialysis work?
- Unfiltered blood that is high in urea is taken from a blood vessel mixed with blood thinners
- Pumped into the dialysis machine where blood and dialysis fluid are separated by a partially permeable membrane
- Blood flows in opposite direction to dialysis fluid, allows exchange to happen between the two where a concentration gradient exists
How does glucose concentration help with dialysis?
- Because it is equal to a normal blood sugar level prevents the net movement of glucose across the membrane as no concentration gradient exists
- Maintain levels of glucose for respiration
How does no urea help with dialysis?
-Large concentration gradient - meaning that urea moves across the partially permeable membrane
What are the advantages of kidney dialysis?(3)
- Cleaned blood - low levels of urea
- No overall change of glucose levels
- Correct water and ion balance maintained or restored
