Connections between the CNS, SNS, ANS

Question 1

Is the SNS monitored and controlled by the CNS?

Answer 1

Yes!

Question 2

What nerves do the spinal cord oversee?

Answer 2

The spinal nerves

Question 3

What nerves do the brain oversee?

Answer 3

The cranial nerves

Question 4

How many cranial nerves does the brain oversee?

Answer 4

12 pairs!

Question 5

Do cranial nerves have afferent OR efferent functions?

Answer 5

They have BOTH!
They can have afferent functions (sensory inputs to the brain FROM the eyes, ears, mouth and nose OR they can have efferent functiong (motor control of the facial muscles, tongue & eyes).

Question 6

Do some cranial nerves have BOTH sensory and motor functions?

Answer 6

Yes, some can modulate both sensation AND movement in the face.

Question 7

The internal ANS is a ____partner in controlling behaviour

Answer 7

Hidden

Question 8

What is the job of the ANS?

Answer 8

To keep the heart beating, liver releasing glucose and regulating the internal organs

Question 9

How does the ANS regulate the internal organs and glands?

Answer 9

By its connections through the SNS and CNS

Question 10

Conscious control of these vegetative activities can be learned by what is the important reason why the ANS must keep working by itself?

Answer 10

Because the ANS must keep working while we sleep + when our conscious awareness is off duty!

Question 11

What are the 2 divisions of the ANS?

Answer 11

The Sympathetic and Parasympathetic

Question 12

What is the role of the Sympathetic divison?

Answer 12

Arouses the body for action and is stimulatory, eliciting a ‘fight or flight’ response. E.g. this works to stimulate the heart to beat faster and inhibiting digestion when we are in times of stress or excertion.

Question 13

What is the role of the Parasympathetic division?

Answer 13

Calms the body down and is inhibatory, eliciting a ‘rest and digest’ respnse. E.g. this wotsk to calm the body down by slowing the heart beat and stimulating digestion to allow us to rest during quiet times.

Question 14

Do all autonomic fibres connect at ‘stops’ en route from the CNS to their target organs?

Answer 14

Yes!

Question 15

Where do arousing sympathetic fibres connect?

Answer 15

They connect to a CHAIN of ganglia near the spinal cord

Question 16

Where do calming parasympathetic fibres connect?

Answer 16

They connect to INDIVIDUAL parasympathetic ganglia near the target organs.

Question 17

Where does the activiation of the sympathetic system start?

Answer 17

In the thoracic and lumbar spinal cord regions. However, the spinal nerves do NOT directly control target organs, instead, the spinal cord is connected to a chain of autonomic control centres (collections of neural cells called ‘Sympathetic ganglia’! These ganglia are collections of nerve cells that function like a primitive brain (to control the internal organs).

Question 18

What part of the parasympathetic system is also connected to the spinal cord?

Answer 18

The sacral region. However, the greater part of the Parasympathetic system derives from 3 cranial nerves.

1) Vagus nerve: Calms most of the internal organs
2) Facial nerve: Controls salivation
3) Oculomotor nerve: Controls pupil dilation and eye movements

Question 19

What is the difference in terms of nerve connections with the parasympathetic and sympathetic systems?

Answer 19

The sympathetic system forms a chain running parallel to the spinal cord while the parasympathetic system connects with parasympathetic ganglia near the target organs.