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Nervous System . Part 1 Biology 12. http://www.youtube.com/watch?v=x4PPZCLnVkA. The Nervous System. An integral part of your body’s communication system. It plays an important role in the smooth functioning of the body.

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nervous system

Nervous System

Part 1

Biology 12

http://www.youtube.com/watch?v=x4PPZCLnVkA

the nervous system
The Nervous System
  • An integral part of your body’s communication system.
  • It plays an important role in the smooth functioning of the body.
  • The nervous system is a complex network of cells which are specialized in function.
homeostasis nervous system
Homeostasis & Nervous System
  • The Nervous System allows the body to respond to changes in the internal and external environments.
  • Communication comes in the form of electrochemical messages relayed to and from the brain, or a series of chemical messengers carried in the blood.
  • Through a series of adjustments, all systems of the body are regulated to maintain the internal environment within safe limits (homeostasis).
two divisions
Two divisions...
  • The nervous system has two main divisions:
    • Central Nervous System (CNS)
    • Peripheral Nervous System (PNS)
central nervous system
Central nervous system
  • Consists of the nerves of the brain and spinal cord.
    • Brain is known as the “cerebrum”
  • Acts as a coordinating centre for incoming and outgoing information.
the cerebrum brain
The Cerebrum (brain)
  • The brain consists of millions of nerve cells that cluster together and interact with each other through the process of neurotransmission.
  • It controls most of the bodily functions like movements, thoughts, speech, sensations and memory.
the spinal cord
The spinal cord
  • The spinal cord is a continuation of the brain and is surrounded by the vertebral bodies that form the spinal column.
  • The spinal cord is divided into four main segments; reach transferring signals to different parts of the body.
video clip
Video clip
  • http://www.youtube.com/watch?v=vGxho71tScM&NR=1
peripheral nervous system
Peripheral nervous system
  • Consists of nerves that carry information between the organs of the body and the central nervous system.
  • It can be further divided into:
    • Somatic nervous system
    • Autonomic nervous system
nerve cells
Nerve cells
  • Information about your body is continuously relayed to your brain for processing and storage.
  • The cells that transfer these messages to the brain and around the body are nerve cells.
cells of the nervous system
Cells of the Nervous system
  • Nerve cells gather & transmits electro-chemical signals.

DID YOU KNOW????

  • Neurons cannot be repaired
  • Some last a life time
  • Approximately 1000 die each day!!!
nerve vs neurons
Nerve vs neurons
  • A nerve is a bundle of neurons attached by connective tissue
neuron notables
Neuron notables
  • Average number of neurons in the human brain = 100 billion
  • Nerve “highway” in the human body contains 100 billion neurons
  • 1000 impluses/sec
types of neurons
Types of neurons
  • SENSORY
    • Carries signals FROM periphery (outside) TO central nervous system for processing
    • Information FROM environment
    • NOTE: detect external stimuli (light, sound, touch, heat, smell, & taste) or internal conditions (blood pressure, CO2level & muscle tension)
types of neurons1
Types of neurons
  • MOTOR
    • Carries signals FROM central nervous system TO body part (e.g. muscles, skin, glands)
    • Respond to sensory neurons
    • Responsible for movement
types of neurons2
Types of neurons
  • INTERNEURONS
    • Connects sensory or motor neurons to central nervous system
    • Carries messages in-between neurons
    • Majority of neurons in the brain are interneurons
parts of a neuron
Parts of a neuron
  • Cell Body
    • Contains all organelles, including a nucleus
  • Dendrites
    • Projections off cell bodies
    • Make connections with other cells
slide18

Dendrites

Cell body

Cell body

Nucleus

Figure 27.3

parts of a neuron1
Parts of a neuron
  • Axon
    • Long cable like projection off cell body
    • Sends messages (nerve impulses)
  • Myelin Sheath
    • Fatty protein that covers/insulates most nerves
    • Increases speed of transmission
    • Formed by Schwann cells
  • Nodes of Ranvier
    • Exposed axon between myelin sheath
slide20

Dendrites

Cell body

Cell body

Axon

Nucleus

Nodes of Ranvier

Myelin sheath

Figure 27.3

parts of a neuron2
Parts of a neuron
  • Synaptic knob
    • End of axon branches
    • Comes near dendrites of adjacent neurons
    • Passes messages across synapse (the space between neurons)
slide22

Signal direction

Dendrites

Cell body

Cell body

Signal pathway

Axon

Synaptic knobs

Supporting cell

Nucleus

Nodes of Ranvier

Myelin sheath

Figure 27.3

direction of message
Direction of message
  • Moves in only one direction
  • From dendrite to cell body, axon, then synaptic knob
slide24

Signal direction

Dendrites

Cell body

Cell body

Signal pathway

Axon

Synaptic knobs

Supporting cell

Nucleus

Nodes of Ranvier

Myelin sheath

Figure 27.3

neurons in action
Neurons in Action
  • The three interconnected functions of the nervous system are carried out by the three types of neurons

Sensory input

Integration

Sensory neuron

Sensory receptor

Motor neuron

Interneuron

Motor output

Brain and spinal cord

Effector

Peripheral nervous system (PNS)

Central nervous system (CNS)

Figure 27.2

let s review video clips
Let’s review: video clips
  • Nervous System explained
  • Nervous System Rap
  • How Neurons Work
slide28
TASK
  • Draw a large motor neuron on a white piece of paper.
  • Label
    • Cell body
    • Nucleus
    • Dendrites
    • axon
  • Myelin sheath
  • Schwann cells
  • Node of Ranvier
  • Synaptic knob
  • Then draw arrows to show the message direction
  • Identify the motor neuron functions
motor neuron
Motor Neuron

Synaptic knob

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