Mammalian Sensory Receptors Flashcards
What do receptors detect?
A change in either internal or external environment
Internal environment
Temperature or blood pressure
External Environment
Spider
What is each receptor specific to?
Only one stimulus
What are receptors?
Are transducers which convert one form of energy into another form of energy
Example One of Receptors
Photo receptors convert light energy to electrical energy
Example Two of Receptors
Thermoreceptors convert light heat energy to electrical energy
-In hypothalamus (internal temp)
-In skin (external temp)
Example Three of Receptors
Chemoreceptors convert chemical energy to electrical energy
-O2+CO2 in aorta/carotid artery
-Olfactory in nose
-Taste buds
Example Four of Receptors
Mechanoreceptros convert movement/stretch/pressure into electrical energy
-e.g. Parcinian Corpuscle
Diagram of Parcinian Corpuscles at rest/not being touched
See Notes
First step of Parcinian Corpuscles at rest/not being touched
-Sodium potassium pumps, pump 3 NA+ out for every 1/2 K+ in.
-Cause the parcinian corpuscle to become more positive on outside/more negative on inside
Second step of Parcinian Corpuscles at rest/not being touched
There are some non-gated potassium channels in the membrane so some potassium diffuses out by facilitated diffusion so it become even more positive on outside/negative on inside
Third step of Parcinian Corpuscles at rest/not being touched
There are anions (positive ions) on inside so even more positive on outside and negative on inside
What does this mean for the Parcinian Corpuscle being more positive on outside and negative on inside?
-Membrane is polarised
-PC has a resting potential of -70 mv
Diagram of Parcinian Corpuscles being touched
See Notes
What is the first part of when Parcinian Corpuscles are touched?
-Pressure is applied and causes connective tissue to stretch/deform to cause stretch-mediated channels to open so NA+ starts diffusing (facilitated) into sensory nerve ending and it become less negative on inside
What happens as more pressure is applied?
More stretch mediated Na+ channel and more Na+ enter
What is happening to the membrane?
Is depolarising and the amount of depolarising/Na+ entering is called the generator potential
What happens is the generator potential reaches the threshold potential?
Causes the voltage gated Na+ channel to open too which causes a huge influx of Na+ into sensory nerve ending
What is the second part of when Parcinian Corpuscles are touched?
When the Na+ floods in, the membrane fully depolarises and it reaches +40 mV on the inside causing an action potential in the sensory neuron
What is all or none law?
An action potential either happens and ALWAYS gets to +40mV or inside or doesn’t happen at all
