Sensory receptors-1

Question 1

What is a grey matter?

Answer 1

Collection of cell bodies in the CNS

Question 2

What is a ganglia?

Answer 2

Collection of cell body in the peripheral nervous system

Question 3

What are the different types of neurons?

Answer 3

1) Bipolar (interneuron)
2) Unipolar (always sensory neuron)
3) Multipolar (motor neuron)
4) Pyramidal cell

Question 4

What are the types of ganglia?

Answer 4

1) Autonomic (cell bodies of postsynaptic neurons)

2) Dorsal root (cell body of sensory neuron)

Question 5

What are the motor signals that goes out of the brain?

Answer 5

1) Autonomic (we cannot control it) “1 pre & 1 post”

2) Somatic (voluntary) one neuron outside the CNS cell body is found in the CNS “grey matter”

Question 6

Describe the route of sensory signals

Answer 6

1) Sensory axon that has a ganglia
2) Synapses in the spinal cord for it to continue along the spino-thalamic tract axon
3) Synapses in the brain to go to the sensory cortex which will signal the motor for movement

Question 7

Describe the somatic route

Answer 7

1) Upper motor neuron from the brain to the spinal cord

2) Lower motor neuron from the spinal cord to the muscle

Question 8

What are the branches of the nervous system

Answer 8

1) CNS
2) PNS

Question 9

What are the branches of the PNS?

Answer 9

1) Motor nervous system
2) Sensory nervous system

Question 10

What are the different sensory receptors we have in our body?

Answer 10

1) Skin
2) Eyes
3) Muscles (pain and position)
4) Ears
5) Nose
6) Tongue

• FYI sensory receptors converts mechanical/chemical/light, etc stimulus o electrical signals, the stimulus must be strong enough to reach the threshold for us to feel it

Question 11

What is the proper definition of a sensory receptor?

Answer 11

They are specialized cells that converts internal/external stimuli into electrical nerve impulse and transmits them to the CNS

• Example of internal stimuli: pain in heart attack, stomach ulcer, kidney stones, bone fracture / temperature in esophagus for hot and cold food

Question 12

How do sensory receptor detect a stimuli?

Answer 12

1) Detects a stimulus by (Being deformed (touch) Receiving light (vision) Receiving chemicals (taste) Detecting change in temp)

2) Stimulus causes a depolarization

3) Depolarization causes a action potential that will be transmitted as a nerve impulse along the neurons and to the sensory cortex in the brain

Question 13

What are the types of receptors?

Answer 13

1) Photoreceptors (Rods & cons)
2) Chemoreceptors (taste & oxygen regulation)
3) Nociceptors (“pain” somatosensory)
4) Thermoreceptors (somatosensory)
5) Mechanoreceptors (somatosensory)

Question 14

What types of stimuli do nociceptors detect and where are they found in the body?

Answer 14

• They can detect mechanical, thermal and polymodal (both mechanical and thermal stimuli), like sharp pricking pain and extreme temperature
• They are found in the skin, bones and heart

Question 15

What type of stimuli do thermoreceptors detect and where are they found in the body?

Answer 15

1) They are active in a specific range of warm and cold where outside that range you will feel pain that is detected by the nociceptors

2) They are found in the skin, digestive tract, liver, & skeletal muscles

Question 16

What are the different types of mechanoreceptors?

Answer 16

1) Pacinian corpuscle
2) Meissner corpuscle
3) Hair follicles
4) Ruffini corpuscle
5) Merkel receptors
6) Tactile discs

Question 17

What is the location, adaptation & the sensation encoded by pacinian corpuscle?

Answer 17

1) Found subcutaneously, and intramuscular

2) They adapt rapidly

3) The sensation they encode is vibration, pressure and tapping

• Pac-man is muscular and rapid and vibrates on pressure

Question 18

What is the location, adaptation & the sensation encoded by meissner corpuscle?

Answer 18

1) They are found in the non-hairy skin

2) They adapt rapidly

3) The sensation they encode is point discrimination, tapping, and flutter

Question 19

What is the location, adaptation & the sensation encoded by hair follicles?

Answer 19

1) Found in hairy skin

2) They adapt rapidly

3) The sensation they encode is velocity, and direction of movement

Question 20

What is the location, adaptation & the sensation encoded by ruffini corpuscle?

Answer 20

1) They are found in hairy skin

2) They adapt slowly

3) The sensation they encode is stretch and joint rotation

• Rough pressure “stretches” the “joint” “skin” “slowly”

Question 21

What is the location, adaptation & the sensation encoded by merkel receptors?

Answer 21

1) They are found in non-hairy skin

2) They adapt slowly

3) The sensation they encode is the vertical indentation of the skin

Question 22

What is the location, adaptation & the sensation encoded by tactile disc?

Answer 22

1) They are found in the hairy skin

2) They adapt slowly

3) The sensation they encode is vertical indentation of the skin

Question 23

What are the different receptors found in the hairy skin?

Answer 23

1) Hair follicles
2) Ruffini corpuscles
3) Tactile discs

Question 24

What are the mechanoreceptors that are found in the non-hairy skin?

Answer 24

1) Meissner corpuscle
2) Merkel receptors

Question 25

What is the difference between a weak stimulus and a strong stimulus?

Answer 25

Weak stimulus has a weak action potential which does not reach the threshold and thus does not activate the action potential receptor, and vice versa

Question 25

What happens if the stimulus increases in intensity?

Answer 25

Amplitude of receptor potential responds less and less as the stimulus strength increases

Question 25

What happens if the stimulus is continous?

Answer 25

• Like the touch of chair for example

The intensity will decrease due to the decrease in receptor activity

Question 26

What is a tonic receptor?

Answer 26

Receptors that reduces the sensation like Merkel receptors

• They start with a high activity, then reduce the firing rate with time making us feel less and less stimulus, like when hearing loud noises for a long time
• They care for the intensity & duration of the stimulus

Question 27

What is a phasic receptor?

Answer 27

They stop the sensation like Pacinian corpuscle they are active at the start and end of a stimuli

• They start with high activity
• Then they will have no activity until the stimulus disappears
• They only care for the onset/offset of the stimulus

Question 28

What are the different tracts we have for sensory signals?

Answer 28

1) Anterolateral (light touch, pain, temperature, etc), they also have a second order neuron that crosses the midline in the spinal cord

2) Dorsal column system (fine touch, pressure, position)

Question 29

What is meant by sensation?

Answer 29

It is the conscious or subconscious awareness of the environment through sensory receptors

Question 30

What is meant by perception?

Answer 30

It is the interpretation of the information by the brain

• Subjective from a person to another