Nervoussystem 110516205922-phpapp02
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Transcript of Nervoussystem 110516205922-phpapp02
The Nervous System
Two main divisions– Central Nervous System
(CNS) includes the brain and spinal cord
– Peripheral Nervous System (PNS) contains nerves which carry info between the CNS and other organs
Central Nervous System
The brain receives impulses and sends impulses back to the body
The spinal cord connects the brain to the body
CNS: The Brain (UP 5)
3 major regions– Cerebrum– Cerebellum– Brainstem
Cerebrum
Cerebellum
Brainstem
CNS: The Cerebrum Largest part of the brain Involved in voluntary activities, intelligence,
and consciousness Divided into 4 lobes
– Frontal - personality– Temporal - auditory
– Parietal - senses – Occipital - visual area
Parietal
Occipital
Frontal
Temporal
CNS: Cerebellum & Brainstem
Cerebellum – balance and coordination
Cerebellum
Brainstem includes the pons and medulla oblongata– Involuntary functions
– heart rate, breathing
Brainstem
Medulla Oblongata
PNS: Peripheral Nervous System All nerves that are NOT part of the brain
or spinal cord Two major divisions of the PNS:
– Sensory division sends impulses from sense organs (ears, nose, etc.) to the CNS
– Motor division send impulses from the CNS to the muscles or glands
PNS: Motor Divisions Motor division is then divided into the
autonomic and somatic nervous systems
Somatic System – regulates activities under conscious control such as muscle movement– Also involved with reflexes
Autonomic Nervous System Regulates automatic, involuntary
actions– Parasympathetic Nervous System
decreases heart rate and stimulates digestion; “rest and digest”
– Sympathetic Nervous System increases heart rate; “fight or flight”
These systems have opposite effects
Neuron Structure (UP 83)
Cell Body
Cytoplasm
Nucleus
Dendrites
MyelinAxon
Muscle (effector)
End Brush Motor End Plate
Neurons Three types:
– Sensory: carry impulses from sense organs to CNS
– Motor: carry impulses from CNS to muscles/glands
– Interneurons: connect motor and sensory neurons
Neural Impulses (UP 83)
Membrane is polarized, more negative inside
Na+ ions enter; membrane depolarizes
Repolarization follows depolarization
Impulse travels the axon
–http://highered.mcgraw-hill.com/olc/dl/120107/bio_d.swf
Neural Impulses Resting potential – polarized state,
negative charge inside membrane Threshold –minimum stimulus needed
to activate a neuron Action potential – depolarization &
repolarization of membrane Myelin increases rate of impulse
Synapses Location where one neuron
transfers an impulse to a cell– Neuron to neuron– Neuron to muscle/gland
Chemicals called neurotransmitters carry signals across a synapse– Acetylcholine and serotonin
Reflex Arc Reflexes prevent injury Impulse travels from sensory neuron
interneuron motor neuron
http://www.sumanasinc.com/webcontent/anisamples/nonmajorsbiology/reflexarcs.html
Reflex Arc (UP 84)
Association Neuron
(interneuron)
Sensory Neuron
Cell Body (Sensory Neuron)
Motor Neuron
Receptors (on dendrites)
Synapse
Synapse
Effector (muscle)Motor End Plates
Animations
Action Potential– http://highered.mcgraw-hill.com/olc/dl/120107/bio_d.swf
– http://outreach.mcb.harvard.edu/animations/actionpotential.swf
Chemical Synapse– http://www.bishopstopford.com/faculties/science/arthur/synapse.swf
– http://highered.mcgraw-hill.com/olc/dl/120107/anim0015.swf– http://outreach.mcb.harvard.edu/animations/synaptic.swf
Electroencephalogram (EEG) Records electrical activity of the brain Diagnosis of neurological diseases: stroke,
epilepsy, tumors, and sleep disorders
Diagnostic Techniques MRI – Magnetic Resonance Imaging uses
radio waves and VERY powerful magnets to create images of the brain
Used to image soft tissue, not bone or teeth
CT Scan Computerized Tomography 3-D x-ray image based on tissue density
– Bone appears white, liquids/gases are black, and various tissues are grey
Used to diagnose tumors
PET Scan Positron Emission Tomography Creates images based on the detection of radiation particles Used to detect tumors, seizure disorders, and evaluate
patients with memory loss