b12 - homeostaesis in action Flashcards
which two parts of the body have thermoreceptors?
- hypothalamus
- skin
vasodilation of blood vessels
- capillaries get wider so a larger amount of blood can flow near the skin surface
what happens when the temperature rises on a hot day?
1) vasodilation of the blood vessels
2) evaporation sweat - produced by the sweat glands and then is evaporated from the skin
3) no shivering
4) hairs and hair erector muscles are relaxed (no goosebumps)
vasoconstriction of the blood vessels
- capillaries get smaller so less blood can flow near the skin surface. no energy is released
where/how is urea produced?
deamination - removes the poisonous part of amino acid
how is urea removed?
through the kidney via urine
kidneys
renal artery
brings deoxygenated blood containing urea and other substances
renal vein
carries oxygenated blood away from the kidney once the urea and other substances have been removed from it
ureter
tube that connects the kidneys and the bladder
what happens when the temperature falls
1) vasoconstriction of blood vessels
2) no sweat produced
3) the body starts to shiver to produce heat for the body
4) hairs and hair erector muscles stand on end to trap air
glomerulus
- acts as a filter to remove water and urea from deoxygenated blood
nephron
each of the functional units in the kidney, consisting of a glomerulus and its associated tubule, through which the filtrate passes before emerging as urine
why do kidneys have a large blood supply?
- all blood has toxins so the more blood filtered through, the better
role of ADH (antidiuretic hormone) in water regulation - high/low ADH
HIGH ADH: increases permeability of kidney tubule - more water reabsorbed by the kidney so less urine
LOW ADH: decreases permeability of kidney tubule, less water reabsorbed by kidney, more urine
maintaining a constant temperature - behavioural
- sweating - removing thermal energy
- goosebumps - hairs standing up to trap a layer of air
- shivering - muscle contractions which require energy
optimum body temperature
37 degrees
why do we want to maintain our body temperature?
if the internal temperature is too high, the enzymes may denature and will no longer be able to catalyse important reactions
ultrafiltration
filters out ALL the small molecules (even the useful ones)
selective reabsorption
sodium, amino acids and glucose (useful molecules) are then reabsorbed from the filtrate back into the blood
how is carbon dioxide removed from the body?
via respiration
how is urea removed from the body?
through the urine
how is the water reabsorbed?
via osmosis (after selective reabsorption)
why do red blood cells not get filtered out?
they’re too big to pass through the permeable membrane
why is urea removed?
if it becomes too concentrated, it becomes poisonous
why do kidneys have a large blood supply?
so that urea can removed from from as mush blood as possible
how is glucose transported back into the blood?
diffusion and active transport
what reaction in the body produces respiration
aerobic respiration
maintaining water and mineral balance
your body has control over urea, excess water and mineral ions removed via kidneys but no control over how much water leaves the lungs and mineral ions and urea removed via the kidneys
where is ADH produced?
the pituitary gland
how is the amount of water in the blood is controlled by the kidneys
- pituitary gland
- releases ADH
- changes permeability of the nephron/ tubule
- water reabsorbed
problems with the kidneys
- damage due to injury
- kidney failure
- bacterial infections
- polycystic kidneys (genetic)
two types of treatment
- kidney dialysis
- kidney transplant
is there active transport in dialysis?
no, there isn’t there is DIFFUSION
what is in dialysis fluid?
water, glucose, ions - same conc as blood so a conc gradient can be maintained
what is dialysis?
removal of waste/cystic product (nearly the same to the function of a kidney)
why does the clean blood flow through a bubble trap?
a pocket of oxygen could lead to further damage eg. an aneurysm
why are there blood thinners in the dialysis process?
to prevent clotting
how does dialysis take place?
dialysis fluid carrying waste products and urea is removed via the use of a dialysis machine
why is the glucose concentration in the dialysis fluid the same as its concentration in blood?
so that there is no net movement of glucose out of the blood via diffusion so that its concentration can be maintained
how does dialysis ensure that the urea is removed?
no urea in the dialysis fluid ensures that there is a large concentration so diffusion will happen at a faster rate
why is dialysis an option?/ what does it do?
it removes urea from the blood when the kidneys themselves cannot
transplants and how they work
- donor needs to be the same blood group and tissue type as the recipient
- can be a relative (who is alive)
- or from a victim of an accident, stroke or heart attacks
- involves operation (risks)
- transplants may be rejected by the immune system
- immunosuppressants - medicines given to suppress the immune system
thermoregulatory centre
hypothalamus
shivering
- causes the muscles to automatically contract
- the process requires energy from respiration
- respiration produces heat which warms us up
sweating
- sweat glands release water, which covers the skin
- heat energy is transferred to this water and once it reaches the surface of the skin, it evaporates
- as it evaporates it takes the heat energy with it - hence cooling you down
