TOPIC 6- Responding to environmental change Flashcards
What is the function of sensory receptors?
Detect changes in surroundings (stimuli)
Each receptor detects different a specific stimuli
Act as transducers
What are transducers?
Transducers convert any energy they sense into a generator potential.
What does does this lead to?
The passage of a stimulus
What is a generator potential?
The depolarisation of the membrane of a receptor cell, as a result of a stimulus
When is an AP generated as a result of the GP?
When the generator potential reaches the threshold potential, an AP is initiated.
What is the All-or-Nothing Principle?
A stimulus must initiate depolarisation above the threshold value to get an AP.
THRESHOLD MET= AP
What are mechanoreceptors?
Tranducers, that transduce mechanical energy of a stimulus into generator potential.
Detect strong pressures (not light touch)
Where are mechanoreceptors found?
Abundant deep in skin, fingers, soles of feet, external genitalia, and joints
Why are mechanorecpetors also found in ligaments and tendons?
to detect a change of direction
What do mechanorecpetors respond to?
Mechanical pressure
What are pacinian corpuscle?
mechanoreceptors that are located on and deep in the skin and contain a sensory nerve ending.
What are the nerve ending in the pacinian corpuscle wrapped around in?
Layers of connective tissue called lamellae
What happens in the pacinian corpuscle when pressure is applied?
(4 details up to GP)
- The membrane is distorted and stretches
- Causes stretch-mediated Na+ ion channels to open
- Na+ ions diffuse into the neurone
- Influx of Na+ produces a GP
What is the relationship between pressure and Na+ ion channels?
The more pressure applied, the more Na+ ion channels are open as the membrane is distorted more and more SM Na+ ion channels .
What does the GP prod. by the pacinian corpuscle cause?
It pushes (propagates) a nervous impulse along the sensory nerve to the CNS.
