nervous system - vanbiljonvanbiljon.yolasite.com/resources/shms321 ch2.pdf · allows information to...
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C H A P T E R 2
Nervous System
Input
Output
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Neuron
Nerve cell
Allows information to travel throughout the body to various destinations
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Receptive Segment
Transmissive Segment
Conductive Segment
Cell Body
Myelin sheath
Motor end plate
Dendrites: receive message
Terminal ending on muscle: sends off message to adjacent neuron
Axon: transmits
message to terminal ending
Myelin sheath: fatty covering or insulator
Skipping of the impulse allowing faster
conduction
Types of Neurons
Sensory neurons
Carry signals to the spinal cord & brain
Motor neurons
Carry signals from the spinal cord & brain
Interneurons
Originate and terminate in CNS
Connect afferents and efferents in CNS
Process incoming signals
Pass response impulse on to motor neurons
Sport Books Publisher
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Types of Neurons cont.
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The Neuron’s Function
Receptive segment (dendrites) Receives continuous synaptic input
(chemical) from other neurons
Conductive segment (axon) Conduction of neural information in the
form of nerve impulse (electrical)
Transmissive segment (axon terminals) Converts electrical nerve impulse to
chemical form (neurotransmitter) and sends it off to dendrites
Receptive
Transmissive
Conductive
Sensory – monitors environment through presence of receptors
Integration – interpretation of sensory information (information processing)
Motor – response to information processed through stimulation of effectors
The Nervous system has three major functions:
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CNS
Brain & Spinal Cord
Control center
PNS
Connects CNS with the rest of the body
Nervous System Divisions
Nervous System
CNS
PNS
Sensory/Afferent
Motor/Efferent
Somatic
Autonomic
Peripheral Nervous System
Peripheral Nervous System
12 pairs of cranial nerves
31 pairs of spinal nerves
8 pairs of cervical nerves
12 pairs of thoracic nerves
5 pairs of lumbar nerves
5 pairs of sacral nerves
1 pair of coccygeal nerves
Spinal Nerve Attachments
Spinal Nerve Attachments (Cont)
CNS: Spinal Cord
Consists of neurons through the holes in the vertebrae
Holes form a continuous canal
Protected by vertebrae, ligaments & cerebrospinal fluid that fills the canal
Cord connects to the brain at the brainstem through the foramen magnum
Functions of Spinal Cord
1. Intermediate nerve center between spinal nerves & brain
Interneurons integrate messages from various sensory impulses
Interneurons can add commands to the msg from the brain
Functions of Spinal Cord (Cont)
2. Major center for reflexes
Interneurons can match incoming sensory impulses directly with motor commands without brain intervention
Grey Matter White Matter
Interneurons, sensory & motor nerve fibers
Grey colour: cell bodies of interneurons and moter neurons
Bundles of axons
White colour: myelin sheaths
Structure of Spinal Cord
Ventral (anterior)
Dorsal (posterior)
White Matter of Spinal Cord
Ascending fibers: sensory information from sensory neurons of body up to brain
Descending fibers: motor instructions from brain to spinal cord
Descending Fibers: Voluntary Movements
Pyramidal tract Function: Transmit
voluntary movement Originates: Motor Cortex and
travels through pyramids of medulla
Fast tract
Extrapyramidal tract Function: Transmit postural
adjustments & learned reflexes
Travels outside pyramids of medulla
Slower pathway: more interneurons: add fine details
CNS: The Brain
Primarily composed of interneurons
Primary functions parallel the 3 types of neurons:
Sensory function
Association function
Motor function
Cerebrum
Diencephalon
Brain stem
Cerebellum
Regions of the Brain
Brainstem
Medulla
Pons
Midbrain
Reticular Formation
Medulla
Controls breathing, talking, swallowing, maintenance of BP
L&R sides= pyramids
At medulla nerve fibers cross the body before entering the spinal cord
Pons
Links higher brain centers to cerebellum
Relay point between brain & spinal cord
Influence breathing
Midbrain
Smallest division of brainstem
Neck & head reflexes
Elementary forms of seeing & hearing
Reticular Formation Formation
•Located in center of brainstem •Net-like neural network •Alerts the higher brain centers On incoming info •Maintains consciousness and alertness
Diencephalon
Thalamus
Hypothalamus
Thalamus
Relay station between higher & lower centers
Integrate info gathered from all senses
Hypothalamus
Regulatory center for activities of the autonomic system
Command center for complex mood & anger, aggression, fear, pleasure, thirst, hunger, sexual behaviour...
Cerebellum
General control & coordination center for movement
Monitor balance, posture & joint movements
Memory capacity for well learned skills
Cerebrum: Cortex Lobes
Frontal Lobe
Premotor Cortex
Motor Cortex
Parietal Lobe
Sensory Cortex
Sensory Association Cortex
Temporal Lobe
Auditory cortex
Auditory association cortex
Occipital Lobe
Visual cortex
Visual association cortex
Sensory Cortex
Touch Proprioception
Sensory Association Cortex
Receive info from
sensory cortex,
visual association cortex &
auditory association cortex
Integrates info and interprets its meaning by comparing it to your past experiences
Visual Cortex
Visual Association Cortex
Stores visual memory and permits perception of sight
Auditory Cortex
Auditory Association Area
Stores auditory memory and permits perception of sounds
Pre-Motor Cortex
Interpret Meaning of Situation
Decide whether to take action or not
Design plan of action
Motor Cortex
Receives action plan from pre-motor cortex
Generate commands for muscle activity