homeostasis Flashcards
definition of homeostasis
the maintenance of a constant internal environment within narrow limits
if there is a stimulus, the negative feedback will restore envt back to norm to og condition
stimulus meaning
the change from normal conditions
(above norm/below norm)
receptor meaning
cells/tissues that detect the stimulus
what is a corrective mechansim
Automatic
Brings about the opposite effect to the stimulus
negative feedbakc definiion
Sequence of events where the body reacts to bring about an opposite effect to the changes detected and restore the normal conditions of the internal environment
principle of homoestasis
Stimulus -> receptor -> corrective mechanism -> negative feedback -> normal condition
a receptor detects a change in stimulus that is a change in envt. nerve impulses are transmitted to hypothalamus to stimulate the effector. effectors carry out the corrective mehcnism that is opp. to the effect of the stimulus to bring the condition backt to normal, and a negative feedback is invvolved
regulating BGC
ting BGC:
Norm: normal BGC
Stimulus: blood glucose concentration below/above norm
Receptor: Islets of Langerhans is stimulated
Corrective mechanisms:
BGC rise above norm:
Islets of Langerhans are stimulated to secrete MORE insulin into bloodstream
Stimulates the liver cells to convert excess glucose into glycogen
BGC returns back to norm
BGC falls below norm:
Islets of langerhans of pancreas is stimulaetd to secrete MORE glucagon into the bloodstream
Stimulates the liver cells to convert the glycogen bac into glucose
BGC returns back to norm
osmoregulation
Norm: normal WP of blood
Stimulus: increase/decrease in WP of blood that changes away from norm
Receptor: Hypothalamus in brain is detects stimulus
Corrective mechanism:
WP higher than norm:
Less anti-diuretic hormone (ADH) released by pituitary gland into the bloodstream
Less ADH trnasported to kidneys
Cells in walls of collecting duct brecomes less permeable to water molecules
Less water molecules selectively reabsorbed into bloodstream
More water excreted
More urine
More diluted urine
WP of blood returns back to norm
WP below nrom:
More ADH is released by pituitary gland into bloodstream
More ADH transported to kidney
Cells in walls of collecting duct becomes more permeable to water molecules
More water molecules selectively reabsrobed back into bloodstream
Less water excreted
More concentrated urine
WP of blood returns back to norm
thermoregulation
Norm: normal blood temp
Stimulus: blood temp decreases/increases above norm
Receptor: temoerature receptors in skin and hypothalamus in brain is stimuated
Corrective mechanism:
When blood temp is higher than norm
(1) vasodilation of skin arterioles, bring more warm blood to skin cap in skin surface, more heat is lost throguh conduction, convection, radiation (CCR)
(2) sweat glands become more active, increased sweat production, more water in sweat evaporates from skin, removes more LHV from skin
(3) metabolic rate decreases to reduce heat production
Body temperature decreases back to norm
When blood temperature is lower than norm:
(1) vasoconstriction of skin, bring lesser warm blood to skin cap in skin surface, less heat is lost throguh CCR
(2) sweat glands less active, less sweat produced, less water in water evaporates, less LHV removed
(3) higher rate of metabolism to increase heat production
(4) shivering, contraction of muscles, cellular respiration of cells, more heat released
(5) contraction of hair erector muscles, hair stand, trap a lauer of air whch is insulayor
hair
when hair erector muscles contract, hair stands and a layer of air is trapped that serves as insuation, reducing heat loss as air is a poor conductor of heat
see skin diagram and identify hairs, sweat glands, temperature receptors, blood vessels and fatty tissue
u can do it
adipose tissues
insulating layer to reduce heat loss, region for fat storage
sweat gland
secrete sweat throguh sweat duct
hair erector muscle
contraction of muscles causes hair to stand, trapping air, reducing heat loss
Why body temperature increases during running:
- vigorous muscle contractions
- muscle cells need more energy
- cells undergo higher ROR
- more heat released
