Sensory Receptors 1

Question 1

What are sensory receptors?

Answer 1

Sensory receptors are nerve endings with specialised non-neural structures

Question 2

What do sensory receptors do?

Answer 2

Sensory receptors are transducers that convert different forms of energy into frequency of action potentials, informing the CNS about the internal and external environment

Question 3

What is sensory modality?

Answer 3

Sensory modality is the stimulis type activating a receptor

Question 4

What is an adequete stimulis?

Answer 4

An adequete stimulis is the type of energy to which a receptor normally responds

Question 5

What can you say about sensory receptors being activated by many stimuli?

Answer 5

Sensory receptors are highly sensitive to one kind of stimuli, but may be activated by another

Question 6

What are some different types of receptors?

Answer 6

Some different types of receptors are:

Mechanoreceptors (mechanical stimuli like touch)

Proprioreceptors (informations about position in space)

Nociceptors (pain)

Thermoreceptors (cold and warmth)

Chemoreceptors (chemical change)

Photoreceptors (responds to the wavelength of light)

Question 7

What does sensory receptor transduction involve?

Answer 7

Sensory receptor transduction involves ion channels opening and closing, adequete stimuli generates a graded potential

Question 8

What is membrane deformation?

Answer 8

Membrane deformation is adequete stimuli in mechanoreceptors and proprioreceptors

Question 9

What does membrane deformation activate?

Answer 9

Membrane deformation activates stretch sensitive ion channels, causing a local graded potential

Question 10

What happens when the graded potential reaches threshold?

Answer 10

When the graded potential reaches threshold an action potential is fired

Question 11

What is frequency coding of stimulis intensity?

Answer 11

This means a larger stimuli produces a larger graded potential which produces higher frequency of action potentials fired

Question 12

What does the number of receptors activated in an area reflect?

Answer 12

The number of receptors activated in an area reflects the stimulis intensity

Question 13

What are some contrasts in the action potentials of some mechanoreceptors?

Answer 13

In some mechanoreceptors if the stimuli persists then action potentials are constantly fired

In others, action potentials are only fired when something changes

Question 14

What is adaptation?

Answer 14

Adaptation is when some mechanoreceptors adapt to a maintained stimulus and only signal change

Question 15

What are the two different kinds of adapting receptors?

Answer 15

The two different kinds of adapting receptors are:

Rapidly/moderately adapting receptors (fire AP at change)

Slowly adapting receptors (constantly fires AP)

Question 16

Why do nocioreceptors not adapt?

Answer 16

Nocioreceptors do not adapt because they are free nerve endings

Question 17

What is the pacinian corpuscle and how does it work?

Answer 17

The pacinian corpuscle is a mechanoreceptor:

1. Mechanical stimuli deforms capsule
2. Stretches nerve endings and opens ion gated channel
3. Na⁺ influx causes graded potential
4. Action potential generated and fired

Question 18

What does rapid adaption occur?

Answer 18

Rapid adaption occurs because the fluid redistributes in the capsule and removes mechnical stress from the nerve ending

Question 19

How do nerve endings respond without a capsule?

Answer 19

Without a capsule, bare nerve endings have no adaptation and fire constant action potentials

Question 20

What are receptive fields?

Answer 20

Receptive fields are somatic sensory neurons activated by stimuli in a specific area

Question 21

What posseses receptive fields?

Answer 21

Sensory receptors posses receptive fields

Question 22

What does our ability to determine two points on the skin depends on?

Answer 22

Our ability to determine two points on the skin depends on:

Receptive field size

Neuronal convergence

Question 23

What is our ability to determine two points on the skin tested by?

Answer 23

The two point discrimination test

Question 24

What is neuronal convergence?

Answer 24

Neuronal convergence is when multiple pre-synaptic neurons input a smaller number of post synaptic neurons

Question 25

What do sensory neurons with neighbouring receptive fields show?

Answer 25

Neighbouring neurons with receptive fields show neuronal convergence

Question 26

What does neuronal convergence allow?

Answer 26

Neuronal convergence allows sub threshold stimuli to summate at the secondary neuron to generate an action potential

Question 27

What leads to an insensitive area?

Answer 27

Neuronal convergence and a large receptive field leads to an insensitive area

Question 28

What is an example of a sensitive and insensitive area?

Answer 28

The lips are sensitive

The back is insensitive

Question 29

What is acutiy?

Answer 29

Acuity is the ability to locate a stimulis on the skin and differentiate it from another closeby

Question 30

When does high acuinty occur?

Answer 30

High acuinity happens when lots of signals from an area goes to the brain, low acuinity happens when less go

Question 31

What is lateral inhibition?

Answer 31

Lateral inhibition is when information from a neuron from a sensory receptor at the end of a stimuli is inhibited by information from the centre

Question 32

What does lateral inhibition allow us to do?

Answer 32

Lateral inhibition allows us to precisely locate stimulis

Question 33

What is tonic level of firing?

Answer 33

Tonic level of firing is a base level of nerve impulses firing when nothing is going on