Week 1

Question 1

What is the definition of Afferent?

Answer 1

Neurons that receive information from our sensory organs and transmit this input to the central nervous system

Question 2

Define Efferent

Answer 2

Neurons that send impulse from central nervous system to your limbs and organs

Question 3

Define peripheral afferent receptors

Answer 3

Stimulation of specialised receptor endings produces a receptor potential
Physical stimulus is then transfixed to electrical signal by activation of specific ion channels on the receptors

Question 4

What does mechanoreceptors sense stimuli due to?

Answer 4

Physical deformation of their plasma membranes

Question 5

What does mechanoreceptors Contain?

Answer 5

Mechanically gated ion channels 
Gates open/close in response to pressure
Touch 
Stretching 
Sound

Question 6

What are mechanoreceptors in the skin described as?

Answer 6

Encapsulated

Unencapsulated

Question 7

What are free nerve endings sensitive to?

Answer 7

Painful stimuli
Hot and cold
Light touch

Question 8

What are 4 primary tactile mechanoreceptors in human skin?

Answer 8

Merkel’s disk
Meissner’s Corpuscle
Ruffini endings
Pacinian Corpuscle

Question 9

What are 2 types of mechanoreceptors?

Answer 9

Slowly-adapting

Rapidly-adapting

Question 10

What is slow adapting nerve fibres?

Answer 10

Send information about ongoing stimulation

Question 11

What is rapidly adapting nerve fibre?

Answer 11

Send information related to changing stimuli

Question 12

What is epidermis?

Answer 12

The outermost later of skin
Provides a waterproof barrier
Creates skin tone

Question 13

What is the dermis?

Answer 13

Beneath the epidermis
Contain tough connective tissue
Hair follicles, sweat glands

Question 14

What are the properties of Merkel’s disk?

Answer 14

Location: upper layer of skin, base of epidermis
Distribution: fingertips and lips
Function: slowly adapting, unencapsulated nerve endings - respond to light touch
Receptive field: small, well defined borders - sensitive to edges - typing on keyboard

Question 15

What are the propertied of Meissner’s Corpuscle?

Answer 15

Location: upper dermis - project to epidermis
Distribution: fingertips and eyelids
Function: respond to fine touch and pressure - low frequency vibration
Type: rapidly-adapting, fluid filled, encapsulated nerve endings with well defined border - responsive to fine detail

Question 16

What are the properties of Ruffini endings?

Answer 16

Location: deeper in the dermis, near base - bulbous corpuscles
Distribution: glabrous and hairy skin
Function: slow-adapting, encapsulated mechanoreceptors - detect skin stretch and deformations within joints - gripping objects and controlling finger position and movements
Contribute to proprioception and kinaesthesia
Detect warmth

Question 17

What are the properties of Pacinian Corpuscles ?

Answer 17

Location: deep in the dermis of both glabrous and hairy skin
Distribution: bone periosteum, joint capsules, pancreas and other viscera, breast and genitals
Function: rapidly adapting mechanoreceptors, sense deep, transient pressure - high frequency vibration

Question 18

What does nerve consist of?

Answer 18

Sensory afferent axon

Motor efferent axon

Question 19

What are nerve axons and their associated Schwann cells bound together by?

Answer 19

Connective tissue - endoneurium

Question 20

What are fascicles enclosed in?

Answer 20

Connective tissue sheath called perineurium

Question 21

What is the whole nerve enclosed in?

Answer 21

Tough coat —> epineurium

Question 22

What does epineurium provide to the nerve?

Answer 22

Mechanical strength

Support

Question 23

What is epineurium continuous with?

Answer 23

Dura Mater

Question 24

What forms the outer and inner components of the perineurial sheath?

Answer 24

Arachnoid and Pia Mater

Question 25

What does cerebrospinal fluid contribute to?

Answer 25

Endoneurial fluid via pial tissue space

Question 26

What are sensory nerve fibres?

Answer 26

Pseudo-unipolar

Question 27

What does pseudo-unipolar neuron consist of?

Answer 27

One axon with two branches: central and peripheral

Question 28

Why are sensory neurons an exception?

Answer 28

They do not have separate dendrites and an axonal process, rather one branched process that serves both function

Question 29

Where are the soma of each pseudo-unipolar neuron located within?

Answer 29

Dorsal root ganglion

Question 30

Where does the axon leave the cell body?

Answer 30

Into dorsal root where it splits into 2 branches

Question 31

Where does the central branch go to?

Answer 31

Dorsal column of the spinal cord where it forms synapses with other neurons

Question 32

Where does the peripheral branch travel through?

Answer 32

Distal dorsal root into the spinal nerve all the way until skin, joint and muscle

Question 33

What can medium-sized DRG neurons give rise to and what can it innervate?

Answer 33

Myelinated axons Innervate skin or muscle structures Muscle structures: Golgi tendon organ or muscle spindles

Question 34

What does peripheral processes of some DRG cells release?

Answer 34

Vasoactive mediators

Question 35

What does the cell body located in the dorsal root Ganglia mediate?

Answer 35

Touch and conscious proprioception

Question 36

What does cell body size of DRG correlate with?

Answer 36

Axon diameter Degree of myelination Conduction velocity Action potential shape

Question 37

What does large sensory cells give rise to?

Answer 37

Myelinated axons

Question 38

What does small sensory cells give rise to?

Answer 38

Unmyelinated axons

Question 39

For cells that are clearly large what is the conduction velocity?

Answer 39

Greater than 2.5 m/s

Question 40

For cells that are clearly small, what is the conduction velocity?

Answer 40

Less than 2.5 m/s

Question 41

What are the two populations of DRG neurons which can be distinguished based on their cytoplasmic appearance?

Answer 41

Small dark neurons | Large light neurons

Question 42

What is white matter?

Answer 42

Surrounds grey matter | Contain myelinated and unmyelinated nerve fibres

Question 43

Where do the white matter fibres conduction information?

Answer 43

Up or down the cord

Question 44

What is white matter divided into?

Answer 44

Dorsal (posterior) column Lateral column Central column

Question 45

Where do A fibre axons ascend to?

Answer 45

Dorsal column nuclei (DCN)

Question 46

Where does C-fibres run in?

Answer 46

Lissauer’s tract and ascend 1-2 segments within cord

Question 47

What are the 4 different regions the spinal cord is divided into?

Answer 47

1. Cervical 2. Thoracic 3. Lumbar 4. Sacral regions

Question 48

What are the 2 enlargements of the spinal cord that can be visualised?

Answer 48

1. Cervical enlargement (C3-T1) | 2. Lumbar enlargement (L1 to S2)

Question 49

How many segments are the spinal cord divided into?

Answer 49

31 segments | 31 pairs of nerves

Question 50

What are the nerves divided into?

Answer 50

``` 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal ```

Question 51

What is the function of afferents?

Answer 51

Pain (ad) | Touch (ab)

Question 52

What is lamina pattern?

Answer 52

Modality specific

Question 53

What are 3 types of spinal cord neurons?

Answer 53

Projections Motoneurons Interneurons

Question 54

What is spinothalamic tract split into?

Answer 54

Lateral spinothalamic: transmit pain and temperature sensation to thalamus Anterior spinothalamic: transmit pressure and crude touch sensation to the thalamus

Question 55

Schwann cells

Answer 55

1:1 axon ratio | PNS myelination

Question 56

Oligodendrocytes

Answer 56

1:many | CNS myelination

Question 57

Astrocytes

Answer 57

Homeostasis

Question 58

Microglia

Answer 58

Immune surveillance

Question 59

What is somatotopy?

Answer 59

Point-for-point correspondence of an area of body to a specific point on CNS