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 True Some information on the right is not found on the left and vice versa. Need a connection – corpus callosum Bundle 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 muscles Linked to intellect and personality Temporal lobe – Sensory – vision, hearing Linked to memory and sensory interp of info Parietal lobe – Sensory – touch and temp. Linked to emotions and interpreting speech Occipital lobe – Sensory – vision Interpret 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!