biology lesson8.1
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Lesson 8.1 Outline of Nervous System
Functions:CommunicationCoordinationControlGathering information
Differences between human and animal NS:1. Language2. Judgment3. Problem solving4. Creativeness5. Passing along
heritage
Neurobiologist – biologist who studies the nervous system.
Neurologist – physician who specializes in disorders of the NS.
Two Divisions of NS:
1. Central nervous system (CNS) – brain and spinal cord/nerves
Central Nervous System
Two Divisions of NS:1. Central nervous system (CNS) – brain and spinal cord/nerves
2. Peripheral nervous system (PNS)
nerves that branch from the CNS.
Peripheral Nervous System
CNS Composed of:1. Brain •protected by cranium•has high levels thought•major organ of NS•Message center•Uses info to formulate ideas•Makes decisions•Communicates to body
CNS Composed of:1. Brain
2. Spinal CordThick bundle nerve fibers within spinal cavityHow brain communicates with most of bodyEnds at first lumbar
PNS Composed of:
1. Cranial nervesNerves that come from brain12 pairsBranch from brain stemTransmits messages from/to eyes, ears, mouth, face and scalp
PNS Composed of:
1. Cranial nerves
2. Spinal NervesNerves that come from spinal cord31 pairsTransmit signals to and from the rest of the body
Brain and spinal cord covered by a triple layer
of protective tissue called Meninges.
Cerebrospinal fluid – bathes the brain and runs through fibers of middle meninge to cushion brain.
Nerves are made of bundles of nerve cells called neurons.
Three parts of neurons
1. cell body • contains the nucleus, found only
in spinal cord and brain.
Three parts of neurons
1. cell body
A mass of cell bodies is called a ganglion.Large mass of ganglion called a plexus.Nerve center – plexus that has a certain function.
Three parts of neurons
1. cell body
2. dendrites – short, branched extensions of cell body that receive nerve impulses and conduct them toward the cell body.
Three parts of neurons1. cell body2. dendrites
3. axon – one long extension which carries impulses to other neurons or cells
Axon branches at terminal end.
Nerve impulses travel from the dendrite to cell body to axon.
GLIAL CELLS – also found in the nervous system are cells that SUPPORT AND INSULATE not functional.
Gray Matter vs. White Matter
Gray matter – within spinal cord and brain composed of cell bodies not wrapped by myelin
White matter – made up of dendrites and axons wrapped in myelin.
Myelin •An insulating material that forms a layer, the myelin sheath, usually around only the axon of a neuron.•It is essential for the proper functioning of the NS.•Myelin is an outgrowth of a glial cell.
3 Types of neurons:1. Sensory neurons – transmit
from sense organs to CNS
2. Motor neurons – transmit from CNS to other part of body
3. Interneurons – neurons withinthe CNS that connect sensory andmotor neurons with each other.
Sciatic Nerve – one of the longest nerves of the body.
Branches from spinal cord of lower back and goes to the leg.
PNS Types of Nerve fibers:1. Mixed – both sensory and
motor neurons. Go from sense organ to spinal cord and send message back.
2. Sensory 3. Motor
Divisions of the PNS1. Somatic – skeletal muscle control
2. Autonomic – responsiblefor all routine body activitiesfreeing the mind toconcentrate on biology
class.
Two divisions ANS:Sympathetic –stimulates when danger, stress, or activeex. Increases heart rate when scaredParasympathetic – stimulates when at rest, or brings things back to normal. Ex. Decreases heart rate after scare is over.