HUBS 191 Lecture 23

Question 1

what are the three types of senses

Answer 1

somatic, visceral and special

Question 2

what are somatic senses

Answer 2

the perception of physical sense like touch and temperature that can provide information about the internal or external environment. typically sensed by the skin, muscle and joints

Question 3

what are visceral senses

Answer 3

visceral means deep down and refers to sense that monitor your internal organs

Question 4

between somatic and visceral which is more precise in terms of location

Answer 4

somatic senses tend to be highly specific whereas visceral senses are often difficult to pinpoint

Question 5

what are special senses

Answer 5

sense detected by highly specialised organs or structures like vision, smell etc

Question 6

what is sensory transduction

Answer 6

the conversion of a sensory stimulus into an action potential

Question 7

what are the two types of receptors

Answer 7

tonic and phasic

Question 8

what type of receptor is continually active to reflex background levels of stimulation

Answer 8

tonic - phasic receptor are normally silent (no APs)

Question 9

why type of receptors send APs when there is a change but stop quickly

Answer 9

phasic - in tonic receptors the AP frequency change when the stimulus intensity changes

Question 10

are tonic receptors slow or fast adapting - what does this tell us about the type of information they transmit

Answer 10

slow adapting - therefore they are used to transmit the most important information

Question 11

are phasic receptors slow or fast adapting - what does this tell us about the type of information they transmit

Answer 11

fast adapting - therefore they are used to transit information that isn’t life or death

Question 12

what is the advantage of having phasic receptors

Answer 12

they only transmit the information that is new. without these receptors we would be in constant sensory overload

Question 13

what are the 4 types of receptors

Answer 13

thermoreceptors, chemoreceptors, mechanoreceptors and nociceptors

Question 14

what are thermoreceptors

Answer 14

nerve endings with temperature gated ion channels that respond to different temperatures and also changes in temperature

Question 15

Are thermoreceptors tonic or phasic

Answer 15

phasic - fast adapting

Question 16

how are temperature stimuli transmitted

Answer 16

temperature stimuli open temperature gated Na+ channels allowing Na+ to enter and depolarise the membrane. if threshold is reached in the thermoreceptors, an AP will fire and propagate to the brain

Question 17

what are chemoreceptors

Answer 17

specialised receptor cells with chemically gated ion channels. they translate changes in chemical concentration to action potentials.

Question 18

are chemoreceptors tonic or phasic

Answer 18

they can be either tonic or phasic depending on the chemical

Question 19

what are mechanoreceptors

Answer 19

nerve endings with mechanically gated ion channels that respond to physical forces that distort the plasma membrane (deformation)

Question 20

what are the three types of mechanoreceptors

Answer 20

tactile receptors, proprioceptors and baroreceptors

Question 21

what are tactile receptors and are they tonic or phasic

Answer 21

a type of mechanoreceptors that respond to light touch - they are mostly phasic (fast adapting)

Question 22

what are proprioceptors and are they tonic or phasic

Answer 22

a type of mechanoreceptors that sense the position of the body ad movement in space which comes from stretch receptors in muscles, tendons and joints. they are tonic (slow adapting)

Question 23

what are baroreceptors and are they tonic or phasic

Answer 23

a type of mechanoreceptor that detects pressure/stretch in vessels within the body - they are tonic (slow adapting)

Question 24

what are nociceptors

Answer 24

nerve endings that respond to noxious stimuli (harmful or painful) typically caused by tissue damage. they either have chemically gated, temperature gated or mechanically gated io channels responding to extreme stimuli

Question 25

are nociceptors tonic or phasic

Answer 25

they tend to be tonic (slow adapting) although some are phasic (fast adapting)

Question 26

what is the intensity of sensation determined by

Answer 26

action potential frequency and number of neurons activated

Question 27

the receptive field is the area encompassed by nerve ____ for a single ____ neuron

Answer 27

endings - sensory

Question 28

what two things affect the discriminatory touch (sensitivity) and ability to localise a stimulus

Answer 28

the size and density of receptive fields

Question 29

how many receptive fields does each neuron have

Answer 29

one

Question 30

larger and more widely spaced receptive fields provide...

Answer 30

less sensitivity and less accurate localisation

Question 31

where would you find large and widely spaced receptive fields

Answer 31

in the arms, legs and torso

Question 32

small and densely packed receptive fields provide...

Answer 32

more sensitivity and more accurate localisation

Question 33

where would you find small and densely packed receptive fields

Answer 33

in the hands, fingers and lips

Question 34

do areas of skin with larger receptive fields have more or less representation in the brain

Answer 34

less because there are fewer neurons involved - remember 1 sensory neuron per receptive field

Question 35

do areas of the skin with smaller receptive fields have more or less representation in the brain

Answer 35

more because there are more neurons involved - remember 1 sensory neuron per receptive field