The Nervous System
Functions of Nervous System
Integrative Function
Motor Function
Sensory Function
detects changes (stimuli) within body and outside body
it analyzes sensory information stores some aspects, and makes decisions regarding appropriate behaviors
it may respond to stimuli by initiating muscular contractions or glandular secretions
Divisions of Nervous System
Neuroglia
Two Primary Divisions
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Consists of brain and spinal cord
Consists of cranial and spinal nerves
Peripheral Nervous Systems
Sematic Nervous System (SNS)
Brings info from skin, special sensory, body wall and limbs to CNS, and motor neurons to skeletal muscles
Autonomic Nervous System
Sympathetic Nervous System
Only occurs in emergencies or in non-committal situation
Brings info from receptors in interval organs to CNS and motor neurons to smooth muscle, cardiac muscle and glands
Nerves
Cell Body
Dendrites
Contains nucleus and other organelles
Receiving portions, short, tapered and highly branched
Myelin
acts as an insulater
Classification of Neurons
Bipolar
Unipolar
Multipolar
Just one process, and are always sensory neurons. Axon terminals are in CNS and cell bodies in ganglia
one main dendrite and one axon-usually found in special sense organs
Several dendrites and one axon- neurons of CNS are mostly this type
Types of Neuroglia in CNS
Astrocytes
Oligodendrocyte
form the myelin sheath for neurons of CNS
star shaped cells with many processes
Microglia
Small,have
Ependymal Cells
Form the cerebrospinal fluid (CSF) and also assist in its circulation
Neuroglia of PNS
Schwann Cells
Satellite Cells
Flattened cells found around cells bodies of neurons in ganglia
supply myelin sheathes to axons in the PNS
Membrane Potential
Cell Generates small voltage across their cell membrane
Resting Membrane Potential
Nerve at rest or inactive
Action Potential
Nerve impulses is transmitted during action potential
If a strong enough, depolarization occurs, threshold potential is reached (+30) and impulse is sent down axon.
Types of Response
Summation
occurs when another stimulus of same type arrives before effect of first stimulus wears off, additive effect of two or more stimuli
Refractory Period
Graded Response
time during which no stimulus can cause another action
stronger stimuli stronger response
Types of Conduction
Continuous Conduction
Soltatory Conductions
myelinated axon "jump" from one node to next- much faster
unmyeliated axon conducts an impulse over its entire surface
Synapse
Presynaptic Neuron
Neuron before the synapse
Postsynaptic Neuron
Neuron after synapse
Brian
4 main parts of the brain
Diencephalon
Cerebellum
Cerebeum
Vermiss
Largest Portion
Superioe to brain stem, surrounds by cerebrum
little brain
A narrow, warm shaped structure in between both sides of the cerebellum
Cerebrum
Longitudinal Fissure
Corpus Callasum
Cerebral Cortex
Dark outer area consists of gray matter: contains cell bodies of 75% of all neurons in the nervouse system
Separates brain into right and left cerebral hemispheres
connects both moispheres
Cerebrum
Temporal above ears
Parietal- top side
Frontal -forehead
Occipital-back
Diencephalon
Thalamus
Surrounded by the third ventricle
Plays a role in emotion, memory, awareness, and cognition
Hypothalamus
under the thalamus
Limbic System
Emotional aspects of behavior & aids in memory the pleasure center
Brian System
Connects Spinal cord to diencephalon
Medulla Oblongata
Cardiac Center
Respiratory Center
Heart Rate
Rate and depth of breathing
Cerebellum
Vermis
Cerebelleur Peduncles
worm shaped structures between the cerebellar hemispheres
Connect cerebellum to other parts of brain
Protections & Covering
Bone -cranium & vertebral
Meninges-three connective tissue layers
Dura Mater- most outer
Archaoid Mater- "spider-web" middle
Pia Mater- inner