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