Divisions of the Nervous System

Question 1

What is the human nervous system?

Answer 1

• A complex network of nerve cells that carry messages to and from the brain and spinal cord to different parts of the body
• Helps all parts of the body communicate with each other
• The brain = powerhouse as controls the nervous system + oversees workings of body + its higher functions provide us consciousness (makes us who we are)

Question 2

What is the Central Nervous System (CNS)?

Answer 2

Comprises of the brain and spinal cord with 2 main functions:
1. Controls behaviour
2. Regulates the body’s physiological processes
- To do so the brain must be able to receive info from sensory receptors and be able to send messages to muscles and glands - this involves the spinal cord (collection of nerve cells that are attached to brain and run length of spinal column)

Question 3

How is the brain divided up into 4 main areas?

Answer 3

1. The Cerebrum
2. The Cerebellum
3. The Diencephalon
4. The Brain Stem

Question 4

What is the Cerebrum?

Answer 4

• Largest part of the brain
• Further divided into 4 different lobes, each with own function
  e.g. frontal lobe is involved in thought and production of speech

Question 5

What is the Cerebellum?

Answer 5

• Sits beneath the back of the cerebrum
• Involved in controlling a person’s motor skills and balance, coordinating muscles to allow precise movements
• Abnormalities can result in a number of problems incl speech, motor problems and epilepsy

Question 6

What is the Diencephalon?

Answer 6

• Lies beneath cerebrum and on top of brain stem
• Within this area are the thalamus & hypothalamus
• Thalamus = acts as relay station for nerve impulses coming from senses, routing them to appropriate part of brain to be processed
• Hypothalamus = regulation of body temp, hunger, thirst. Links endocrine system to nervous system

Question 7

What is the Brain Stem?

Answer 7

• Responsible for regulating autonomic functions essential for life incl breathing, heartbeat, swallowing
• Motor + sensory neurons travel through brain stem allowing impulses to pass between brain and spinal cord

Question 8

What is the Spinal Cord?

Answer 8

• Main function = relay info between brain and rest of body
• This allows brain to monitor and regulate bodily processes (digestion, breathing) and coordinate voluntary movements
• Connected to different parts of body by pairs of spinal nerves which connect with specific muscles and glands
• Contains circuits of nerve cells that enable us to perform some simple reflexes without direct involvement of brain
• If damaged, areas supplied by spinal nerves below damaged site will be cut off from brain and stop functioning

Question 9

What is the Peripheral Nervous System (PNS)?

Answer 9

• All nerves outside CNS make up the PNS
• Function = relay nerve impulses from the CNS to rest of body and from body back to CNS
• Divides into the Somatic NS and the Autonomic NS

Question 10

What is the Somatic Nervous System?

Answer 10

• Made up of 12 pairs of cranial nerves and 31 pairs of spinal nerves
• These have both sensory and motor neurons:
• Sensory (relay messages to CNS)
• Motor (relay info from CNS to other parts of body)

Question 11

What is the Autonomic Nervous System?

Answer 11

• Governs the brain’s involuntary activities (e.g. stress, heartbeat, digestion) and is self-regulating
• Necessary - all vital bodily functions would not work so efficiently if we had to think about them

Question 12

How is the ANS divided?

Answer 12

1. Sympathetic nervous system
2. Parasympathetic nervous system
   - Both divisions tend to regulate the same organs but have opposite effects because of neurotransmitters.
   - Sympathetic uses noradrenaline (stimulating effects)
   - Parasympathetic uses acetylcholine (inhibiting effects)

Question 13

What is the Sympathetic Nervous System?

Answer 13

• Primarily involved in responses that help us to deal with emergencies (increasing HR, blood pressure and dilating blood vessels in muscles)
• Neurons from SNS travel to virtually every organ + gland, preparing body for rapid action if necessary
  e.g. causes the body to release stored energy, pupils dialate, hair to stand
• Slows bodily processes that are less imp in emergencies (digestion, urination)

Question 14

What is the Parasympathetic Nervous System?

Answer 14

• Relaxes individual again once the emergency has passed
• Slows heartbeat down and reduces blood pressure
• Digestion begins again under PNS influence
• Involved with energy conservation + digestion - sometimes referred to as body’s rest and digest system.