AOS 4 sac Flashcards
what is homeostasis
the (relatively) constant physiological state of the body despite changes (fluctuations) in the external environment
what are the most important systems involved in homeostasis
nervous system and endocrine system
what is the endocrine system
system of ductless glands that produce hormones and release them directly into the bloodstream
are exocrine glands considered part of the endocrine system. If no why not
no, they do not produce hormones so aren’t considered part of the system
What are the two types of stimulus response models
open stimulus-response model and closed homeostatic stimulus-response model
what are the 5 components of the stimulus response models
stimulus, receptor, control center, effector, response
what happens in the stimulus stage
a change, either increase or decrease, in the level of an internal variable
what happens is the receptor
the structure detects the change and send signals to the control centre
what is the control centre
the structure (central nervous system) that evaluates the change against the set point for that variable and sends signals to the effector about the correction needed
what is the effector
the structure that adjusts its output to make the required correction
what happens in the response stage
the corrective action is taken
what are the two types of feedback
negative and positive
what happens in negative feedback
maintains the body’s internal environment at a relatively steady state
what happens in positive feedback
amplify (increase) a response in order to achieve a particular result (pooping, birth)
what is the term for how body temperature is regulated
thermoregulation
what is thermoregulation controlled by?
hypothalamus
what is the hypothalamus
a region of the brain that has thermoreceptors that monitor the core temperature
what does the hypothalamus do to maintain homeostasis
it registers change in the temperature and then it coordinates nervous and hormonal responses to counteract the changes and restore homeostasis
what happens in the stimulus stage of decreased body temperatures
the body temperature decreases below normal ranges (set point ranges)
what happens in the receptor stage of decreased body temperatures
the decrease in temperature is detected in the thermoreceptors in the skin, organs and hypothalamus
what happens in the control centre stage of decreased body temperatures
the hypothalamus will send signals via the nervous and hormonal systems to effectors
what are the effectors of decreased body temperatures
blood vessels in skin, skeletal muscles and brown adipose tissue (BAT)
what happens in the response stage of decreased body temperatures
reduced blood flow to the skin vessels (vasoconstriction) , shivering, BAT heat production and increased metabolic heat from BAT
what behaivourial changes occur when your core temperature is below average
having a hot drink, standing in front of a heater and rubbing your hands together
what happens in the stimulus stage after high body temperatures
the increase in body temperature is above normal
what happens in the receptor stage after high body temperatures
increase detected by thermoreceptors in skin, organs and hypothalamus
what happens in the control centre stage after high body temperatures
hypothalamus sends signal via nerves to effectors
what are the effector after high body temperatures
blood vessels in skin, sweat glands
what happens in the response stage after high body temperatures
vasodilation of skin vessels, initiation of sweating
what are some behaivourial changes for increased body temperature
removing layer of clothing, using an ice pack and resting in the shade
what are hormones
chemicals that coordinate different functions in your body by carrying messages through your blood to organs, skin, muscles and other tissues
what are 3 types of hormones
thyroxine, insulin and glucagon
what does thyroxine (T4) do
T4 can speed up metabolic activity in cells causing heat to be produced
how is T4 supplied to the target cells
thyroid stimulating hormones (TSH) acts on the thyroid gland, causing it to produces thyroid hormones including T4
what does insulin do
pancreas will release insulin and this instructs the target cells to absorb glucose
what does glucagon do
pancreas will release glucagon and this instructs the target cells to release glucose
summary of glucagon and insulin
insulin lowers blood glucose, glucagon increases blood glucose
what are alpha cells
cells that secrete the hormone glucagon
what are beta cells
cells that produces insulin
what is happening in the stimulus stage of decreased blood glucose
decrease in blood glucose
what is happening in the receptor stage of decreased blood glucose
alpha cells of pancreas
what is happening in the control centre stage of decreased blood glucose
alpha cells of the pancreas secrete the hormone glucagon
what is happening in the effector stage of decreased blood glucose
liver cells, body cells
what is happening in the response stage of decreased blood glucose
increase in blood glucose by the release of glucose into the blood from the liver
what is the stimulus in increased blood glucose levels
increase in blood glucose
what is the receptor in increased blood glucose levels
beta cells of pancreas
what is the control centre in increased blood glucose levels
beta cells of pancreas secrete the hormone insulin
what is the effector in increased blood glucose levels
skeletal muscle, adipose tissue, liver
what is the response in increased blood glucose levels
decrease in blood glucose by: uptake by muscle and adipose tissue and glycogen formation in liver
what is diabetes
a condition where blood glucose is too high because the body’s cells cannot take up glucose in the normal way
why isn’t there enough insulin with people with diabetes
the beta cells in the pancreas are destroyed so cannot produce insulin
what do people with diabetes have to do to restore insulin levels
inject themselves with insulin
