Week 5: The nervous system (ANS and somatic)

Question 1

What makes up the afferent division of the CNS?

Answer 1

Sensory stimuli (eyes and ears) + visceral stimuli (from organs)

Question 2

What makes up the efferent division of the CNS?

Answer 2

somatic nervous system (skeletal muscle) + ANS (smooth muscle - involuntary)

Question 3

Instead of single neurons connecting the CNS to organs, what does the ANS have?

Answer 3

Autonomic ganglion

Question 4

Which type of ganglionic fibre is myelinated and which ones are unmyelinated?

Answer 4

Preganglionic fibres are myelinated and postganglionic fibres are unmyelinated.

Question 5

Where are sympathetic ganglia usually located?

Answer 5

Sympathetic ganglia are usually located close to the CNS.

Question 6

Where are parasympathetic ganglia usually located?

Answer 6

Parasympathetic ganglia are usually located close to the target organ, if not embedded in it.

Question 7

What type of preganglionic axons tend to innervate more than 20 cell bodies in the ganglia?

Answer 7

Sympathetic preganglionic axons

Question 8

What is the prevertebral ganglia?

Answer 8

When many sympathetic ganglia are aligned in a row on each side of the spinal chord

Question 9

What is the neurotransmitter for the preganglionic neurons for the sympathetic and parasympathetic NS?

Answer 9

Acetylcholine

Question 10

What is the neurotransmitter used for postganglioic neurons in the sympathetic nerves?

Answer 10

Noradrenaline

Question 11

What is the neurotransmitter used for postganglioic neurons in the parasympathetic nerves?

Answer 11

Acetyl choline

Question 12

What are the two types of ACh receptors?

Answer 12

Nicotinic and muscarinic

Question 13

What is the effect of nicotine or ACh binding on a nicotinic receptor?

Answer 13

-Posititive ions flow (Na+ and K+)
-Effect is ionotropic
binding of the ligand to the channel directly alters the permeability of the channel
-Often stimululatory

Question 14

Generally where are nicotinic recepors found?

Answer 14

In the post-synaptic side in the ganglia

Question 15

Generally where are nicotinic recepors found?

Answer 15

In the post-synaptic side in the ganglia

Question 16

How does a muscarinic ACh receptor work?

Answer 16

When ACh (or muscarine) binds, they release G proteins (in the sub-membrane space), which begin a cascade of information.
Metabotropic effect

Question 17

Which ganglion have a nicotinic receptor?

Answer 17

The pre-ganglionic sympathetic and para-sympathetic NS

Question 18

Which ganglion has a muscarinic receptor?

Answer 18

The post-ganglionic para-sympathetic axon

Question 19

What type of receptors are epinephrine receptors?

Answer 19

G protein, when adrenaline/noradrenaline binds they release G proteins

Question 20

What are the types of adrenaline receptors?

Answer 20

Alpha 1 and 2 and beta 1 and 2

Question 21

What is the main function of the cerebellum?

Answer 21

Coordinates movement by selecting the correct sequences

Question 22

What is the main function of UMNs?

Answer 22

They produce voluntary movements

Question 23

What is the main function of LMNs?

Answer 23

produce muscle contraction via motor units (extend out towards the skeletal muscle).
They are responsible for efferent information

Question 24

Are the neurons that control the muscles upper or lower motor neurones?

Answer 24

UMNs

Question 25

Describe the brief actions in a somatic reflex arc

Answer 25

1. Sensor (or receptor) 2. Afferent pathway, fibres leading into the spinal cord or brainstem 3. An integrating centre, the grey matter of the spinal cord or brainstem synapse 4. Efferent pathway, to the muscles 5. Effector muscle gives response.

Question 26

Describe the patella reflex

Answer 26

1. Tap the patella ligament which tugs on other ligaments, stretching the muscle spindles 2. Sensory information feeds into the spinal cord and grey matter (monosynaptic reflex)- the tight muscle 3. Sends information to the extrafusal fibres (purple) and excites them (via the nicotinic receptors)

Question 27

Describe the action of the antagonistic muscle in the patella reflex

Answer 27

1. The afferent impulses are sent from the stretch receptor to the spinal cord 2. Efferent impulses to the alpha motor neurons cause contraction of the stretched muscle that resists/reverses the stretch 3. Efferent impulses to the antagonist are dampened This is the part of the reflex which has an interneuron, the interneuron is inhibitory to the hamstring muscle, so it is a negative feedback reflex arc

Question 28

What is proprioception?

Answer 28

how your body knows where your limbs and other parts are at any given time

Question 29

What is the muscle made up of?

Answer 29

Muscle spindle, golgi tendon organ and the extrafusal muscle fibres

Question 30

What is the role of the extrafusal muscle

Answer 30

the fibres that contract to give movement and a lot of force

Question 31

What happens when the muscle stretches?

Answer 31

The muscle cells get wider because they contain cytoplasm and stretch the sensory nerve fibres, sending information forwards

Question 32

The motor neurons sends information to what two networks?

Answer 32

Sensory neurons -The muscle cells get wider because they contain cytoplasm and stretch the sensory nerve fibres, sending information forwards Green - gamma neurons are telling the intrafusal neurons to contract

Question 33

Why does the intrafusal fibres contract along with the extrafusal fibres?

Answer 33

- To ensure one smooth contraction - To ensure the body knows how extended (contracted) the extrafusal muscle is

Question 34

What is a Golgi tendon organ

Answer 34

Located in the tendons and approx. 10-15 fibres are connected to each Golgi tendon organ

Question 35

What is the function of the Golgi tendon organ?

Answer 35

When collagen fibrils are pulled taught/become straight they Golgi tendon organ afferent nerve is activated. The Golgi tendon organ afferent nerve is good at sensing the force of muscle contraction

Question 36

Why is the Golgi tendon organ important?

Answer 36

- Prevents the body from pushing too hard on tendons - To measure the force to help with proprioception

Question 37

Systems tend to be constantly firing, would that not be a waste of energy?

Answer 37

- Because any small increase or decrease in the x axis will give a large effect on the y axis - Allows the system to be very sensitive for changes - The brain only looks at the action potentials