Sensory receptors

Question 1

What is the area covered by a sensory receptor known as

Answer 1

Receptive field

NOT Sensory field

Question 2

What are different classifications based on type of stimulus detected?

Answer 2

Mechanoreceptors
Thermorecetpors
Electromagnetic/photoreceptors
Chemoreceptors
Nociceptors

Question 3

What is the conversion of a sensory effect e.g. touch into the nervous signal in a sensory neurone known as

Answer 3

Signal transduction

Question 4

Describe signal transduction in sensory neurones

Answer 4

Stimulus detected in receptive field

Distortion etc causes opening of mechanically gated na+ channels that results in small amount of depolarisation this is known as the generator potential

Generator potential must be great enough to overcome threshold for an action potential to be generated int he sensory neurone and thus result in detection of the stimulus by the brain

Question 5

What is adaptation in relation to sensory neruones?

Answer 5

Prolonged stimulus can in some causes result in frequency of nerve impulses being decreased even though the stimulus hasn’t changed

(e.g. a hot shower hot at firs then becomes quite nice)

Question 6

What Rapidly adapting or phasic neurones?

Answer 6

Respond maximally but briefly to stimuli. Response decreases in frequency if stimulus is maintained

Question 7

What are slowly adapting or tonic neurones?

Answer 7

Respond comparatively slower to stimulus however as long as the stimulus is present the frequency of impulses is maintained

Question 8

What is a modality?

Answer 8

Modality is our perception of a particular sensory stimulus
e.g. taste smell vison
When we look at a tree we see a tree not photons of light that allow us to!

Question 9

What is crude and discriminative touch ability? What is needed for them?

Answer 9

Crude touch ability is to know something has made contact with the skin which is rapid. Its localisation and shape is not determined

Discriminative touch ability is where and what shape and texture of the stimulus is
Receptor shave much smaller receptive fields to allow for this

Question 10

What are the two rapidly adapting corpuscles of touch

Answer 10

Messiner corpuscles

Hair root receptors

Question 11

What are messiner corpsules?

Answer 11

Located in dermal papillae
found in the palm sole and nipple and sexual organs
Ovoid in shape stack of modified flattened schwann cells with a central nerve fibre
enclosed by connective tissue capsule
rapidly adapting mechanoreceptor allowing for rapid 2 point tactile discrimination

Question 12

What are hair root receptors?

Answer 12

Free nerve endings wrapped around the root of a hair

detect movements on the skin that disturb hairs

Question 13

What are the two tonic receptors of the skin that are tonic ie slowly adapting?

Answer 13

Merkel’s discs:
slowly adapting allow for discriminative touch small receptive field. plat shaped nerve ends in contact with merkel cells on stratum basalae

Ruffini corpuscles located in dermis on hairy skin slowly adapting stretch receptors that respond when skin is stretched
large receptive field

Question 14

What receptor detects pressure?

Answer 14

Pacinian corpuscles
Abundant in dermis subcutaneous tissue joint ligaments genitalia
very large receptive fields stacks of lamellae forming onion like rings with nerve ends in the middle
Rapidly adapting

Question 15

What receptors detect temperature?

Answer 15

Cold receptors:
stratum basale of epidermis detect temps between 10-40oC
Hot receptors located in dermis saller diameters c fibres
Temps below 10 or above 48 detected by nocioceptors

Question 16

What receptors detect pain?

Answer 16

nociocetptors
free nerve endings in every tissue of the body except brain

Fast localised immediately you know where the pin that is in you foot is. Medium diameter myelinated afferent neurones

Slow second or more after stimulus is a gradual increase in pain and response for burning and throbbing pain