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Chapter 37 Nervous System.

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Presentation on theme: "Chapter 37 Nervous System."— Presentation transcript:

1 Chapter 37 Nervous System

2 Nervous System-receives and relays information about activities within the body and monitors and responds to internal and external changes

3 Three main functions of the nervous system
1. Sensory Input 2. Integration 3. Motor Output

4 Three main functions of the nervous system

5 Structures of the central Nervous system (CNS)
1. brain 2. spinal nerve cord in vertebrates

6 Motor output is the conduction of signals from the CNS to the effector cells such as muscles

7 How are signals conducted
Signals are conducted by nerves Nerves are bundles of neurons which are wrapped in connective tissue

8 Sensory and motor neurons are collectively called the peripheral nervous system

9 Neuron-structural and functional unit of the nervous system

10 Four main parts of a neuron
1. Cell body 2. Dendrites 3. Axon (action potential is generated here number 20) 4. Axon terminals

11 Neuron

12 Synapse-The site of contact between a synaptic terminal of a neuron and a target, such as another neuron, a muscle cell, or a gland, is called a

13 Pre-synaptic cell and post-synaptic cells of a synapse

14 Reflex arc-the simplest type of nerve circuit
Has to be at least one sensory neuron and one motor neuron

15 Ganglia and nuclei Collections of cell bodies of neurons.
Ganglia are found in the peripheral nervous system Nuclei are found within the brain.

16 Schwann Cells Cells that form the insulating sheaths around axons
Located outside the Central Nervous System It is made of myelin

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18 Membrane potential All cells have an electrical charge difference across their plasma membrane called the membrane potential It exists because the different concentration of certain ions across the cell membrane The membrane potential of an unstimulated neuron is called the resting membrane potential These ions move across the membrane either by being pumped by membrane proteins or by simple diffusion through ion channels.

19 Membrane potential

20 Resting membrane potential

21 All cells have a membrane potential
However, only certain cells such as neurons and muscle cells have the ability to generate large changes in their membrane potential These cells are called excitable

22 Action Potential If a sufficiently strong stimulus causes depolarization to reach “threshold potential” it triggers a different type of response called an action potential

23 Two factors that affect the speed at which an action potential travels down an axon
The diameter of the axon, the larger the diameter the faster the action potential The presence of myelin around the axon, myelin insulates the axon and allows the action potential to travel quicker

24 The “motor division” of the peripheral nervous system is divided into two functional divisions, called the somatic and autonomic nervous systems

25 What do they do? The somatic nervous system carries signals to skeletal muscle The autonomic nervous system carries signals to cardiac muscle, smooth muscle, and glands

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27 Sympathetic and Parasympathetic of the Autonomic nervous system
The autonomic nervous system consists of two divisions that act on body organs with opposite affects The Sympathetic Division correlates with an activation of the fight or flight response The Parasympathetic Division causes a calming effect and a return to an emphasis on self-maintenance functions

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