Homeostasis- Homeostasis Flashcards
1.1- tolerance limits, 1.2- homeostasis and negative feedback
what is homeostasis?
The maintenance of relatively constant internal environment
what is a stimulus?
a detectable change
what are sensory receptors?
sensory receptors detect stimuli in external/ internal environments
what are the four types of sensory receptors and what are their functions?
- Chemoreceptors: for detecting chemical related stimulus.
- Thermoreceptors: for detecting temperature related stimulus.
- Photoreceptor: or detecting light/colour related stimulus.
- Mechanoreceptors (Pressure/pain receptor): for detecting stretch, touch, and sound stimulus.
describe the role of effectors
effectors can be organs or glands which execute a change in response to a stimulus
give an example of an effector
contracting muscles and gland secreting hormones
what is the stimulus-response model?
- Sensory receptor recognises stimulus.
- Sensory neuron relays stimulus to CNS (brain + spinal cord) via interneurons.
- Interneurons relay message to motor neuron.
- Motor neuron relay message to effectors
- Effectors initiate a response.
what is negative feedback?
- Negative feedback is a stimulus-response that works in the opposite direction.
e.g. Stimulus is an increase in overall body temperature (→) Response is decreased body temperature (←). The response inhibits the initial stimulus
what is a negative feedback loop?
- A negative feedback loop is a continues cycle of negative feedback. Said negative feedback cycle, or loop, continues to maintain homeostasis.
what is positive feedback? (with example)
Positive feedback works in the same direction as the stimulus. Example is childbirth. Stimulus is an increase in bodily contractions during childbirth (→). Response is the release of oxytocin, which increases the number/rate of contractions further (→).
