B12 - Homeostasis in action Flashcards
What is the optimum temperature in the body
37 degrees
Why is controlling body temperature important
to make sure enzymes work
What are three things that cause internal body temperature to change
fevers from disease, transfer of energy during exercise, change in external temperature
What part of the body controls temperature
- where is it
thermoregulatory centre
- hypothalamus in brain
how does the thermoregulatory centre get information about the temperature of the skin
temperature receptors in the skin that send impulses to the thermoregulatory centre
How does the body cool down
- vasodilation happens
- more sweat is produced as energy is transferred to the environment
- hairs lie flat
What is vasodilation
when capillaries near the skin get bigger to allow for more blood flow
What is vasoconstriction
capillaries close to skin get smaller so less blood flows
How does the body keep warm when it is cold outside
vasoconstriction
- no sweat
- shivering which required energy to be transferred
What are the two main poisonous waste products
urea and carbon dioxide
How is carbon dioxide produced in the body
respiration
Why must carbon dioxide in the body
- how is it removed
dissolved carbon dioxide produces an acidic solution that affects enzymes
- using a concentration gradient to the lungs, then it is exhaled
What is urea
the nitrogenous water produced by the breakdown of excess amino acids in your liver
How is urea moved from the body
it passes from the liver cells into the blood. it is filtered out of blood by the kidneys and passed out in urine
What are the three ways water is lost from the body
breathing, sweat, urine
Why is urine produced
to balance water and mineral concentrations, to remove urea
are
-exhalation
- sweat
- urine
controlled water loss
exhalation and seat are not, urine is
What happens if body cells lose or gain too much water
they do not function efficiently
What is the function of the kidneys
remove toxins from blood and maintain the water balance
What do kidneys do if you drink too little / much water
little - concentrated urine is produced, water is conserved
lots - dilute urine is produced with lots of water
How are mineral ions excreted
through urine, sweat
How do the kidneys work
- glucose, mineral ions, urea and water move out of blood into kidney
- around 99% goes back to blood, rest becomes urine
- this trickles down into bladder
What blood vessel brings blood to the kidney
renal artery
What blood vessel brings blood to the kidney
renal vein
Why do blood cells and proteins not enter the kidneys
too big to leave the blood
What happens to the substances taken in by the kidney
all the glucose is reabsorbed
- water and minerals are reabsorbed based on what is necessary
- all urea is excreted
What is the process of controlled amounts of water and minerals being reabsorbed called
selective reabsorption
What type of system controls the amount of water in the blood
- Which hormone does it involve
negative feedback system
- ADH Anti-diuretic hormone)
How does the system of water balance in the body work
- if the blood is too concentrated with solutes, the pituitary gland releases lots of ADH
-this makes the kidneys reabsorb more water - If it is too dilute less ADH is produced
- large volume of dilute urine is produced
Why do kidneys fail
accidents, genetic problems
What is the effect of not having functioning kidneys
toxins such as urea build up and damage cells
What are the two effective methods of treating kidney failure
dialysis
kidney transplant
What is dialysis
a process where the kidney’s function is done artificially
How does a dialysis machine work
blood leaves the body and flows between a partially permeable membrane
- on the other side is dialysis fluid with the same concentration of useful substances
- there is no net movement of substances such as glucose
- excess substances are removed via diffusion down a concentration gradient
How long do dialysis sessions tend to last
around 8 hours, a few times a week
What are the drawbacks of dialysis
a very controlled diet is needed, with a relatively low protein intake
- long time must be spent at a dialysis machine
- the balance only lasts a relatively short time so you might feel unwell
- over years keeping balance can get harder
- causes damage to the body
Why are organs sometimes rejected
the donor’s antigens are different to the recipients so the immune system might attack it
How can the risk of rejection be reduced
- similar antigens
- immunosuppressants
What is the issue with using immunosuppressants
they prevent the patient from dealing with normal diseases so they feel more ill
What are the drawbacks of having a kidney transplant
- won’t last forever
- long waiting lists
- requires immunosuppressants
What are the advantages of dialysis
- much more available
What are the advantages of having a kidney transplant
- can have a normal life
- less expensive than dialysis
