Homeostasis Flashcards
Homeostasis
the constant state of the internal environment despite changes in the external environment.
stimulus response model
stimulus, receptor, modulator, effector and response
stimulus
the change in the external or internal environment
receptor
stimulus is detected by a recepetor which passes on either chemical or electrical signal onto the modulator
Modulator
usually the brain, receives stimulus information and process it to then send a message to the effector.
Effector
is a molecule, cell or organ that responds to the message from the modulator to produce a response
response
is then any change of the targe cell/ organ or organism as a result of the initial signal.
negative feedback
a response which acts to reduce the difference between the current state and the required state
Positive feedback
a response which acts to increase the difference between the current state and the required state
Thermoregulating
to maintain an even core body temperature.
Increase heat generation
- thyroxine
- adrenaline and noradrenaline
- shivering
thyroxine
Neurosecretory cells in the hypothalamus produce thyrotropin releasing hormone
TRH is transported to the pituitary gland where it stimulates the release of Thyroid stimulating hormone
TSH is transported in the blood to the thyroid where it stimulates the production of thyroxine.
increases metabolic rate
Adrenaline and Noradrenaline
the hypothalamus stimulates the adrenal gland to release adrenaline and noradrenaline
cause skeletal muscles and brown fate to increase metabolic rate
Shivering
hypothalamus sends message via motor neurons to skeletal muscles.
cause them to contract and shiver. friction heats you up.
Reducing heat loss
- vasoconstriction
- piloconstriciton.
