NERVOUS SYSTEM

CENTRAL

SPINAL CORD

BRAIN

PERIPHERAL

MOTOR

SENSORY

Central Nervous System (CNS)

- FUNCTION: Transmission and Processing

- Stores memories, thought process, receives signals and appreciates responses

SPINAL CORD

- Located inside the backbone

- Entire nervous system

Grey Matter: Head of neurons (cell body)
White Matter: Axon/extended arms

- Spinal cord is the link between the central nervous system and the peripheral nervous system

- If damaged, paralysis

BRAIN

Fore Brain

Processes signals
Stores memories
Creates thoughts

Mid Brain

Coordinates signals
Reactions between PNS and CNS

Hind Brain

Heart beat, respiration, breathing
Most basic functions

Figure 1. Spinal Cord Anatomy

Figure 2. Brain

Peripheral Nervous System (PNS)

- Nerves, neurons, sensory organs OUTSIDE the spinal cord

- Takes signals and transmits to the CNS

Types of Neurons:

1. Sensory

2. Association -Present in the brain

3. Motor - Very long transmission lines

4. Effectors - Receive signals from brain, carries out effect

STRUCTURE OF A NEURON

Cell body - Contains nucleus, cytoplasm, cell surface membrane and organelles. Irregular in shape

Dendron - The nerve fibres that transmit nerve impulses towards the cell body. The end branches of dendrons are called dendrites.

Axon - The nerve fibres that transmit nerve impulses away from the cell body; usually long.

Myelin Sheath - The layer of fatty substances enclosing many nerve fibres (like a rubber sheath for insulation of an electricity-conducting wire)

Nodes of Ranvier - The regions where the myelin sheath is absent

Axon Terminals - Transmit nerve impulses to the effector

Figure 3. Diagram of a neuron

Figure 4. Reflex Arc

THE REFLEX ARC

- Feel something, responded, but brain did not process

- All neurons involved except accessory

-Impulses from point of pain to spinal cord to effectors

BASIC OPERATIONS OF THE NERVOUS SYSTEM

1. Determine type of stimulus

2. Signal intensity of stimulus

3. Integrate response from many sources

4. Initiate and direct responses

The Brain

Why do we need a brain?

- Use memory and process stimulus to regulate body

- Appropriate movement critical for survival

Parts of the Brain

HIND BRAIN

1. Medulla - Controls autonomic functions

2. Pans - Controls sleep stages

3. Cerebellum - Coordinates movement, stores some motor memory (muscle memory)

MID BRAIN

1. Reticular formation - 'traffic cops' of brain

2. Filters sensory input allowing concentration

3. Filtering can be affected by higher thought

FORE BRAIN

1. Thalamus - Relay station (channeling sensory information

2. Limbic system - Basic emotions, drives and behaviors

3. Pituitary Gland - Secretes hormones

4. Cortex - Higher thought

CORTEX

- Thought and emotion

- Sensory processes

- Motor control

- Wiring is plastic: Specialization can change, e.g. blind person has better hearing

LEFT BRAIN - Right Body (Practical Numericals)

RIGHT BRAIN - Left Body (Creativity)

MEMORY

Long term - 'Working memory', distinct things you remember

Short term - Remembered for only a few days

SENSORY RECEPTORS

Photoreception - Sight, pupils

Chemoreception - Taste, pain

Mechanoreception - Hearing, sound waves from environment to cochlea

Thermoreception - Touch, cold and hot things, direct from PNS

Figure 5. Diagram of brain

Hearing

1. Ear gathers sound waves

2. Inner ear bone amplifies sound

3. Sound transmitted to cochlea

4. Hair cells on basilar membrane vibrate certain frequencies and send signals to auditroy nerve

5. Loud sounds can damage these hairs permanently

Figure 6. Diagram of ear

Sight

1. Light enters eye through cornea and pupil

2. Light focuses by convex lens

3. Light strikes retina and stimulates receptors

SYNTHESIA

- Cross sensory perceptions

- Experiencing flashes of particular colors or textures when hearing sound.

Figure 7. Diagram of eye