Week 2 Lecture 1: The Central Nervous System

Question 1

What is the central nervous system (CNS)?

Answer 1

The brain and the spinal cord

Question 2

What is the peripheral nervous system (PNS)?

Answer 2

All neurons and parts of neurons (cell bodies in the CNS and axons in PNS) outside of the CNS

Question 3

What two nervous systems is the PNS comprised of?

Answer 3

The somatic nervous system and the autonomic nervous system

Question 4

What is the function of the somatic nervous system?

Answer 4

Controlling voluntary action via skeletal muscle

Question 5

What is the function of the autonomic nervous system?

Answer 5

Visceral functions (involving internal organs) such as heart rate and breathing

Question 6

What is a part of the autonomic nervous system?

Answer 6

The enteric nervous system

Question 7

What is the function of the enteric nervous system?

Answer 7

Controls digestion and the movements of the gut, it gets input from the CNS but can also work independently

Question 8

Where are most neurons?

Answer 8

In the CNS, 86 billion in the brain and 1 billion in the spinal cord

Question 9

What cells other than neurons are found in the nervous system?

Answer 9

Glial cells

Question 10

What is the function of glial cells?

Answer 10

Support and protect neurons.

Question 11

What is considered grey matter?

Answer 11

Nerve cell bodies, unmyelinated axons and dendrites

Question 12

What is a cluster of neurons in the CNS called?

Answer 12

Nuclei

Question 13

What is a bundle of axons in the CNS called?

Answer 13

Tracts

Question 14

What is a cluster of neurons in the PNS called?

Answer 14

Ganglia

Question 15

What is a bundle of axons in the PNS called?

Answer 15

Nerves

Question 16

Does the CNS use a lot of energy?

Answer 16

Yes, despite the brain being less than 2% of the body’s mass, it receives 15% of the blood pumped by the heart and consumes 1/2 the body’s glucose

Question 17

Does the CNS use more energy than a computer?

Answer 17

No, the CNS requires substantially less energy than a computer (40 watts = brain)

Question 18

How does the CNS save energy?

Answer 18

Communication between neurons (action potentials/spikes) is expensive and the energy supply to the CNS only supports low level firing therefore the CNS has to use its energy sparingly (only 4% of neurons are firing at any given moment, one spike per neuron every 6 seconds)

Question 19

What type of signals do the dorsal and ventral root in spinal nerves carry?

Answer 19

The dorsal (back) root carries afferent (incoming, sensory) signals and the ventral (front) root carries efferent (outgoing) signals from the CNS to the body e.g. motor signals

Question 20

Where is grey matter located in the spinal cord?

Answer 20

It is found mainly in the middle of the spinal cord and has butterfly shape with a dorsal and ventral horn on each side

Question 21

What are the types of nuclei found in the grey matter of the spinal cord and what is their respective positions? (2)

Answer 21

• Somatic and visceral sensory nuclei are in the dorsal horn
• Autonomic efferent nuclei and somatic motor nuclei are found in the ventral horn

Question 22

Where does somatic sensory nuclei get signals from?

Answer 22

The skin

Question 23

Where does visceral sensory nuclei get signals from?

Answer 23

The viscera (internal organs)

Question 24

Where does autonomic efferent nuclei send signals to?

Answer 24

Glands and smooth muscle

Question 25

Where does somatic motor nuclei send signals to?

Answer 25

Skeletal muscle

Question 26

What are ascending tracts and where can they be found in the spinal cord?

Answer 26

Carry sensory signals to the brain and are mainly dorsal

Question 27

What are descending tracts and where can they be found in the spinal cord?

Answer 27

Carry signals from the brain and are mainly ventral

Question 28

What are the tracts that stay in the spinal cord called?

Answer 28

Propiospinal tracts

Question 29

What is a spinal reflex (example)?

Answer 29

When the spinal cord responds to stimuli without consulting the brain e.g. knee-jerk reflex

Question 30

What are 6 major divisions of the brain?

Answer 30

The cerebrum, diencephalon, midbrain, pons, medulla and cerebellum

Question 31

What structures make up the brain stem and what is it’s function?

Answer 31

The midbrain, pons and medulla make up the brain stem which is the main control center of autonomic function and reflexes e.g. breathing, swallowing, vomiting

Question 32

Which cranial nerves start in the brains stem?

Answer 32

3, 10 and 12

Question 33

What are cranial nerves?

Answer 33

Nerves that enter or leave the brain rather than the spinal cord

Question 34

What structures make up the diencephalon?

Answer 34

Hypothalamus, thalamus, pituitary gland and pineal gland

Question 35

What is the function of the thalamus?

Answer 35

Processes information going in and out of the cerebral cortex i.e. relay centre

Question 36

What is the function of the hypothalamus?

Answer 36

Regulates behavioural drives e.g. fight or flight and endocrine and autonomic homeostasis

Question 37

What is the function of the pituitary and pineal glands.

Answer 37

Secreting hormones

Question 38

What structures are included in cerebral grey matter?

Answer 38

Cortex, limbic system and the basal ganglia

Question 39

How are the two hemispheres of the cerebrum connected together?

Answer 39

The connected via the corpus callosum, a large bundle of myelinated axons

Question 40

Do the functions of the two hemisphere differ?

Answer 40

Yes, we have cerebral lateralization. The left hemisphere is associated with language and math while the right hemisphere is associated with spatial and touch analysis

Question 41

What are the 4 lobes of the brain (found in each hemisphere)?

Answer 41

Frontal, parietal, temporal and occipital

Question 42

What structure is found in each hemisphere and is apart of the limbic system?

Answer 42

The cingulate gyrus