Nervous System

Question 1

Key Features of Nervous System

Answer 1

1) NS is a specialised network of cells & our primary communication system.
2) It is based on electrical & chemical signals.
3) Has 2 main functions:
–> To collect, process & respond to info in the environment.
–> To co-ordinate the working of different organs & cells in body.

Question 2

CNS - Structure & Function

Answer 2

Made up of brain & spinal cord:

BRAIN:
1) Brain is centre of conscious awareness.
2) Made up of billions of interconnected neurons.
3) Cerebral cortex (outer brain layer - 3mm thick) is highly developed in humans & is what distinguishes our mental functions from other animals.
4) Is divided into 2 hemispheres & different lobes.

SPINAL CORD:
1) It is an extension of the brain & responsible for reflex actions.
2) Passes messages to & from the brain.
3) Connects nerves to PNS.

Question 3

Reflex Action

Answer 3

1) Reflexes are reactions to stimuli that are rapid and automatic as sensory input is immediately acted upon by the spinal cord without input from the brain.

Stimulus → Receptor → Sensory neuron → Relay neuron → Motor neuron → Effector → Response

2) Spinal reflexes are important for survival because they allow the body to react very quickly.

Question 4

PNS - Structure & Function

Answer 4

Peripheral Nervous System:
1) Nerves transmit messages to & from the CNS and muscles/organs.
2) Is subdivided into:
- Autonomic Nervous System
- Somatic Nervous System

Question 5

ANS

Answer 5

1) Governs vital functions in body - e.g. breathing, heart rate, digestion, sexual arousal & stress responses.
2) Subdivided into:
- Sympathetic NS
- Parasympathetic NS

Question 6

SNS

Answer 6

1) Governs muscle movement & receives info from sensory receptors.
2) Associated with conscious and voluntary activities.
3) Involved in the relay of sensory and motor information to and from the CNS.
4) It consists of sensory and motor neurones:
- Sensory neurones carry info from sensory receptors TO the CNS.
- Motor neurons carry info AWAY from the CNS to the muscles.

Question 7

Sympathetic Nervous System

Answer 7

1) Activates internal organs to increase energy & arousal for fight or flight.

During Adrenaline Rush:
- Increases Heart Rate
- Increases Breathing Rate
- Dilated Pupils
- Inhibits Digestion
- Inhibits Saliva Production
- Contracts Rectum

Question 8

Parasympathetic Nervous System

Answer 8

1) Works to conserve energy & store body’s resources, allows digestion & metabolism to occur.

Rest & Digest:
- Decreases Heart Rate
- Decreases Breathing Rate
- Constricts Pupils
- Stimulates Digestion
- Stimulates Saliva Production
- Relaxes Rectum

Sympathetic and parasympathetic have complementary functions and work in together to maintain the body’s homeostasis (A state of equilibrium, in which biological conditions are maintained at optimal levels).

Question 9

Diagram of NS

Answer 9

Human Nervous System –> Peripheral & Central NS

Central Nervous System –> Brain & Spinal Cord

Peripheral Nervous System –> Autonomic & Somatic NS
Autonomic Nervous System –> Sympathetic & Parasympathetic NS