The Central Nervous System

Spinal Cord and Brain

The Spinal Cord

Carries sensory nerve messages from receptors to the brain.

Relays motor nerve messages from the brain to muscles, organs and glands.

Comes out of the skull through an opening called the foramen magnum.

It continues down through the backbone.

Two types of Nerve Tissue

1) White matter• Composed of

myelinated nerve fibres from the sensory and motor neurons.

Grey Matter

Consists of non-myelinated interneurons

Remember these interpret sensory information and connect neurons to outgoing motor neurons

Getting the information in and out of the spinal cord.

Sensory nerves enter the spinal through the dorsal root ganglion

Motor nerves leave through the ventral root ganglion

The Brain

Weighs about 1400g (3lbs)

Contains more than 100 billion neurons.

Each neuron may have from 1000 to 10,000 synaptic connections with other nerve cells.

Some quick math…..

All of those connections result in as many as 100 trillion synapses in the brain.

Amazingly complex, beats up the PC and the Mac combined!

                                                                  

More than a thinker and decision maker…

The brain is the body’s main key to homeostasis, regulations of body processes from cellular respiration to the functioning of organs and systems.The nerves and receptors receive the information but the experience of the senses occurs in the brain.Continues to work at night.

Brain structure

The human brain is mostly water (about 75%)

Gelatin consistency suspended in cerebrospinal fluid.

If not for all of this support the brain would sag!

Glial Cells

Glial cells make up 90 percent of the brain's cells. Glial cells are nerve cells that don't carry nerve impulses. The various glial (meaning "glue") cells perform many important functions, including: digestion of parts of dead neurons, manufacturing myelin for neurons, providing physical and nutritional support for neurons, and more.

Eg. Schwann cells

What kind of Brain do you have?

Many people have a tendancy to have Left Brain thinking or Right Brain thinking

Some people, may find it hard to tell as the neurons seem to act and react equally.

Sort of TrueSome information on the right is not found on the left and vice versa.Need a connection – corpus callosumBundle of nerves allowing communication between hemispheres.

Four major divisions of the brain

1) Brainstem• Contains:

Midbrain Pons Medulla oblongata

2) Cerebellum• Second largest

division• Found at the base of

the skull

3) Diencephalon• Contains:

Thalamus Hypothalamus Epithalamus Ventral thalamus

4) Cerebrum• 85% of brain tissue –

largest division• .

Lobes of the Cerebrum

Frontal lobe – control of voluntary musclesLinked to intellect and personality

Temporal lobe – Sensory – vision, hearingLinked to memory and sensory interp of info

Parietal lobe – Sensory – touch and temp.Linked to emotions and interpreting speech

Occipital lobe – Sensory – visionInterpret visual information

Mode of thinking – The Left

Orderly - planned

Rational

Analytical – step by step

Abstract

Linear

Cause and effect

Reliance of language

Prefers certainty

Notices differences

The Right

Intuitive

Putting together pieces to form a whole

Concrete

Subjective

Holistic

Reliance on Image

High tolerance for ambiguity

Spontaneous

Notices similarities

Oh I see….

Activity on p. 453

Go through Part II-IV

Read eye and hearing for tomorrow – it will be brief – then on to Feedback Mechanisms!