PACK 26: RECEPTORS Flashcards
(41 cards)
What are receptors?
Groups of specialised cells that detect a specific stimulus and may generate electrical impulses in response.
What type of stimulus do photoreceptors detect?
Light
What type of stimulus do mechanoreceptors detect?
Pressure
What type of stimulus do thermoreceptors detect?
Temperature
What type of stimulus do baroreceptors detect?
Blood pressure
What type of stimulus do chemoreceptors detect?
Chemicals (e.g., CO2)
What occurs when a specific stimulus causes depolarisation of the membrane in the receptor?
A generator potential is produced.
What is the relationship between the size of the stimulus and the generator potential?
The greater the size of the stimulus, the larger the generator potential.
What happens if the generator potential exceeds a certain threshold value?
An action potential is produced and transmitted in a sensory neurone.
What are Pacinian corpuscles?
A type of mechanoreceptor found deep in the skin that responds to changes in pressure.
Where are Pacinian corpuscles located?
In the skin of fingers, soles of the feet, joints, tendons, and ligaments.
How do Pacinian corpuscles generate a potential?
They have stretch-mediated Na+ protein channels that open under pressure.
What is the role of the gel-filled lamellae in Pacinian corpuscles?
To filter stimuli; slow pressure application does not deform the membrane.
What is the structure of the retina in the eye?
Contains two types of photoreceptors: rods and cones.
Where are cone cells mainly located in the retina?
In the fovea.
What is the function of rod cells?
They cannot distinguish colors and produce information in black and white.
What pigment do cone cells contain?
Iodopsin
What is the trichromatic theory?
The idea that color vision relies on three types of cones: blue, green, and red.
What is red-green color blindness caused by?
Inability to produce either red or green sensitive cones due to a recessive allele on the X chromosome.
What is retinal convergence?
More than one rod forms a synapse with a bipolar neurone.
How does retinal convergence affect sensitivity?
It provides rod cells with greater sensitivity.
How do cone cells differ from rod cells in terms of synapses?
Each cone forms a synapse with a single bipolar neurone (1:1 ratio).
What is the average heart rate of a healthy adult during rest?
70 – 75 beats per minute.
What is the role of the sinoatrial node (SAN)?
It is the natural pacemaker of the heart that conducts impulses across the atria and ventricles.
