Ch. 10 Nervous system:

Nervous Tissue and Brain

Function of

Relays messages (motor)

Monitors changes in body systems (sensory)

Responds to stimuli (sensory)

Maintain homeostasis (sensory)

Integrative – information is brought to CNS info is put together

Central Nervous system

Includes brain and spinal cord

Control center, coordinate body activities

Peripheral Nervous sys.

Nerves that carry messages to and from the central nervous system

Cells of the Nervous System

Neuroganglia – glial cells, nerve glue

Supports, protect and nourish the neurons

2. Neurons

Parts of :Cell bodyDendrites – receive impulseAxon – carries impulse awayMyelin sheath- white fatty material

Schwann cells (pns) Neurilemma (outdside

the sheath) Nodes of Ranvier

Types of Neurons

Sensory neurons (afferent) – carries impulse to brain and spinal cord.

Types of Neurons

Motor neurons (efferent) – away from brain and spinal cord.

Types of Neurons

Interneurons or association neurons – relay impulses from sensory to motor neurons.

White matter vs Gray Matter

White matter White because of

myelin

Gray matter Cell bodies,

interneurons, nonmyelinated fibers

Nuclei – clusters of cells in CNS

Ganglia – cell cluster in PNS

The Nerve Impulse

Action potential – steps in the nerve impulse

3 stages of : polarization, depolarization, repolarization

Step 1: Polarization

Resting state of a neuron

Sodium/possium pump – sodium ions out of cells and potassium ions into cells

Polarization continued

Inside of the cell is – charged

Outside of cell is + charged

Due to sodium-potassium pump2 K+ ions go in as 3 Ca++ go out

http://faculty.washington.edu/chudler/introb.html

Step 2: Depolarization

Due to stimulation

Inside of the neuron becomes + charged.

Na+ rushes into the cell

Step 3: repolarization

Return to resting state

Due to the pumping out of K+.

Na+ blocked

Inside of cell negative

Continues to synapse

Synapse

Brain: structure and function

4 main parts of the brain:

Cerebrum

Diencephalon

Brain stem

Cerebellum

Cerebrum

Largest part of the brain

Corpus collosum - Right and left hemispheres

Cerebral cortex – gray matter covering the cerebrum

                    

Cerebrum Continued

Function of cerebral cortex – learning, reasoning, language, memory

Markings of: gyri (elevations) and sulci (grooves)

Diencephalon

Thalamus – Relay station for sensory

fibers between cerebrum and lower brain.

Hypothalamus - Body Temperature Emotions Hunger Thirst Circadian Rhythms

Cerebellum

Coordinatin of voluntary muscle movements

Muscle tone

Brain Stem

Midbrain-relay station, hearing, vision

Pons – relay station, breathing rate

Medulla Oblongata – relay center, heart rate, blood pressure, respiration

Ventricles

Protection

Bone

Meninges – 3 layers of connective tissue

Cerebrospinal fluid –

Blood brain barrier – cells associated with blood vessels that supply the brain with blood.

Aging Brain

Enlargement of the ventricular system: the volume of the ventricles

Widening of sulci (the grooves) on the surface of the brain.

Reduced brain weight and brain volume: loss of neurons.

Neurological disorders: Alzheimer's disease, Parkinson's disease and stroke are more common in the elderly.