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Nervous System. Transmission of Nerve Signals for Communication Coordination and Regulation of Body Systems. Structure of a Neuron. Dendrites (receive signals). Cell Body (maintains cell metabolism). Myelin Sheath (insulator). Axon bulb. Axon (conducts signals).

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nervous system

Nervous System

Transmission of Nerve Signals for

Communication

Coordination and Regulation of Body Systems

structure of a neuron
Structure of a Neuron

Dendrites(receive signals)

Cell Body(maintains cell metabolism)

Myelin Sheath(insulator)

Axon bulb

Axon(conducts signals)

Dendrite of anotherneuron

Axon of anotherneuron

types of neurons

Receives information from environment

Carries signal between sensory and motor neurons

Generates a response

Types of Neurons
slide4

gaps in myelin sheath

formed by Schwann cells

bundle of nerve fibers

axon

transmission of nerve impulse along a neuron
Transmission of Nerve Impulse Along a Neuron
  • Involves a change in charge across the neuron’s membrane, caused by the movement of ions
  • Action Potential = rapid depolarization and repolarizationof membrane
electrical events during an action potential

80

40

Recorded Potential(millivolts)

0

-40

-80

Time (milliseconds)

Electrical Events During AnAction Potential

Action Potential

Extracellular Fluid(uncharged)

2

depolarization

Threshold

RestingPotential

3

repolarization

1

EPSP

polarized

IPSP

resting potential depends on ionic gradients

2

Resting Potential Depends on Ionic Gradients

Net negative charge insideneuron

Inside:

  • Potassium ionsare pumped intocell

Na+

Na+

Cl-

  • Large organic moleculescannot pass through membrane

Cl-

Na+

Org-

K+

Org-

K+

Org-

K+

Org-

Org-

Org-

Na+

K+

K+

Cl-

Cl-

Outside:

K+

Org-

Org-

  • Sodium ions arepumped out

Na+

Na+

Cl-

Org-

  • Chloride ionsfound in extra-cellular fluid

Cl-

K+

action potential
Action Potential

2. Potassium flows out of neuron through open channel, causing repolarization

1. Sodium flows into neuron through open channel, causing depolarization

inside

inside

outside

outside

transmission of nerve impulses between neurons

synapse

14

Transmission of Nerve Impulses Between Neurons
  • Signal is carried by neurotransmitters that diffuse across the space between neurons
    • Synapse: junction between neurons
    • Synaptic cleft: space between neurons
  • Neurotransmitters bind to receptors on next neuron, opening ion channels
structure and operation of the synapse

1 Actionpotential isinitiated

Structure and Operationof the Synapse

2 Action potentialreaches axon bulb

Pre-synaptic cell

3 Synaptic vesiclesreleaseneurotransmitter

5 Action Potential can be triggered in post-synaptic cell

4 Neurotransmitter binds to receptor and opens ion channel

Post-synaptic cell

transmission between neurons
Transmission Between Neurons
  • Neurotransmitters can be
    • Stimulatory: initiate action potential
      • Acetylcholine
    • Inhibitory: prevent action potential
      • Dopamine
  • After acting on the post-synaptic neuron, neurotransmitters are removed from the synaptic cleft
    • Acetylcholinesterase breaks down acetylcholine
slide14

19

Neurotransmitters carry signals to

muscle cells to stimulate contraction.

applying your knowledge
Applying Your Knowledge
  • Potassium Ions (K+)
  • Neurotransmitters
  • Sodium Ions (Na+)
  • Which one is responsible for
  • Transmission of a nerve impulse across a synapse?
  • Depolarization of a neuron’s membrane?
  • Transmission of a nerve impulse along an axon?
  • Repolarization of a neuron’s membrane?
nervous system organization

Spinal Cord

Brain

Autonomic Nervous System(involuntary)

Somatic Nervous System(voluntary)

Parasympathetic Division(maintenance or relaxation)

Sympathetic Division(stress or activity)

Nervous System Organization

Central Nervous System

Peripheral Nervous System

parts of the brain

sends sensory input to cerebrum

homeostasis

breathing, heart rate, blood pressure

Cortex: thinking, learning, memory, speech movement, senses

Parts of the Brain

musclecoordination

autonomic nervous system

dilates pupils

constricts pupils

constricts bronchioles

dilates air passages

speeds heart

slows heart

decreases stomach and intestinal activity

increases stomach and intestinal activity

Autonomic Nervous System
applying your knowledge1
Applying Your Knowledge
  • Central Nervous System
  • Somatic Nervous System
  • Autonomic Nervous System
  • Which one
  • Is responsible for increasing breathing rate when you start running?
  • Includes the spinal cord?
  • Controls skeletal muscle movement?
nervous system disorders
Nervous System Disorders
  • Alzheimer Disease: gradual loss of neural function due to tangles and plaques associated with axons
  • Parkinson Disease: deficiency of dopamine causes tremors, rigidity, shuffling gait
  • Huntington Disease: uncoordinated movements and degenerative neurological symptoms beginning at middle age, due to autosomal dominant inheritance