SENSORY PATHWAY AND STIMULUS INTERPRETATION

Question 1

What happens to the signal from the receptors?

Answer 1

All signals from the receptors are transmitted to the brain through nerves (somatic or ANS)

Question 2

Why is it that some impulses are transmitted more rapidly than others?

Answer 2

Due to differences in conduction velocities of nerve fibers

Question 3

What is the reason for this differing conduction velocities?

Answer 3

Due to differences in size @ diameter and/or the presence or absence of myelin

Question 4

What is the example for nerve fiber subtype beta for sensory and motor?

Answer 4

Touch and pressure

Question 5

How fast is the conduction velocity for the sensory and motor for delta nerve fiber subtype (touch, pressure, temperature, fast pain) ?

Answer 5

Moderate

Question 6

Why is the nerve fiber type C is slow conduction velocity?

Answer 6

Because the diameter is small and it is unmyelinated

Question 7

All sensory information from the somatic segments of the body enter the spinal cord through the ………..

Answer 7

Dorsal column-mediated lemniscal system @ anterolateral system

Question 8

What is the type of stimulus transmitted by dorsal column- medial lemniscal pathway?

Answer 8

Fine touch, proprioception and vibration. 2 point of discrimination

Question 9

Desc/explain the pathway of dorsal column-medial lemniscal pathway.

Answer 9

> The type of impulses that transmitted in the dorsal column- medial lemniscal pathway are fine touch, vibration, proprioception and 2 points discrimination.
The fibers enter the dorsal column pass without interuption to the dorsal medulla.
Dorsal medulla is the first neuron
In the dorsal medulla, they synapse in the dorsal column nuclei.
The second order neuron decussate @ cross immediately to the opposite side of the brain stem and continue up to the thalamus through the medial lemnisci
The medial-lemniscus fibres terminates in the ventral posterolateral nucleus of the thalamus
The third order neuron travel to the somatosensory area which located in the postcentral gyrus of the cerebral cortex

Question 10

List the types of impulses that transmitted through anterolateral pathway.

Answer 10

1. Crude touch
2. Pain
3. Sexual sensation
4. Tickle
5. Itch
6. Temperature

Question 11

Desc/ explain the anterolateral pathway.

Answer 11

> The type of impulses transmit by the anterolateral pathway are crude touch, temperature, pain, sexual sensation, itch and tickle
The fibre enter the dorsal root
The fibre then synapse
Next, the fibre cross over immediately to the lateral and anterior of the white matter and continues upward to the brain as
- lateral spinothalamic tract ( pain, temperature)
- anterior spinothalamic tract (crude touch, pressure)
The fiber terminate in the ventral posterolateral nucleus of thalamus
The third order neuron travel to the somatosensory area which located in the postcentral gyrus of the cerebral cortex

Question 12

What is the differences between anterolateral system and dorsal column system

Answer 12

In anterolateral system, the signal ascend the spinal cord via anterior or lateral spinothalamic tract. The types of impulses that transmitted by the anterlateral system are crude touch, pain, temperature, sexual sensation, itch and tickles. The axon in the anterolateral system composed of unmyelinated axon and a smaller diameter. Hence, in the anterolateral system, the transmission or the conduction velocity is slow. The spatial orientation in the anterolateral system is a low degree.

However, the signal ascend the spinal cord in the dorsal column system is via the dorsal column. The types of impulses transmitted by the dorsal column system are fine touch, vibration, proprioception, and 2- point discrimination. The axon in the dorsal column system is composed of myelinated axon and it has bigger diameter. Hence, the transmission in the dorsal column is much faster or rapid. Lastly, the spatial orientation in the dorsal column system is high degree.

Question 13

List 5 differences anterolateral system and dorsal column system

Answer 13

Anterolateral system:

1. the type of impulses are crude touch, pain, temperature, sexual sensation, itch and tickes
2. the axons are unmyelinated and has smaller diameter
3. it has slow transmission
4. has low degree of spatial orientation
5. the signal ascend the spinal cord via anterior or lateral spinothalamic tract

Dorsal column system:

1. the type of impulses are fine touch, vibration, proprioception and 2-point discrimination
2. the axons are myelinated and has bigger diameter
3. the transmission is rapid
4. has higher degree of spatial orientation
5. the signal ascend the spinal cord via dorsal column

Question 14

List the somatosensory area 1

Answer 14

Thigh
Thorax
Neck
Shoulder
Hand
Fingers
Tongue
Intra abdominal

Question 15

List the somatosensory area 2

Answer 15

Leg
Arm
Face

Question 16

TRUE OR FALSE

A. The amount of primary somatosensory cortex devoted to a body part is not proportional to the absolute size of the body surface
B. The amount of primary somatosensory cortex devoted to a body part is not proportional to the relative density of cutaneous tactile receptors located on that body part
C. Lips and hands have small representation area than other body part

Answer 16

A. The amount of primary somatosensory cortex devoted to a body part is not proportional to the absolute size of the body surface (TRUE)
B. The amount of primary somatosensory cortex devoted to a body part is not proportional to the relative density of cutaneous tactile receptors located on that body part (FALSE: proportional)
C. Lips and hands have small representation area than other body part (FALSE: larger)