1. Central Nervous System

2. Table of contents Introduction Electrochemical impulse generation
Synaptic transmission
How is a reflex arc formed

3. Function Maintain homeostasis Control automatic functions
React to stimuli

4. Set up Central nervous system Periphiral nervous system
Sensory pathways
Motor pathways
Autonomic nervous system
Somatic nervous system

5. Periphiral nervous system
Named because its located around the central nervous system
Divided into sensory neurons and motor neurons
Motor neurons can be divided into the automatic and somatic nervous systems

6. Autonomic nervous system
Responsible for involuntary body functions.
Heartbeat
Breathing
Digestion
Etc
Divided further into sympathetic and parasympathetic nervous systems

7. Sympathetic Parasympathetic Controls fight or flight response
Bladder relaxaion
Parasympathetic
Maintain normal body function
Controls pupil dilation
conserves physical energy
Slows heart rate

8. Central nervous system
Consists of the brain and spine
Recieves information
Controls the body’s response

9. Structure Of Nervous system
Made up of neurons
Runs through the entire body
Sends signals to muscles and to glands

10. Neurons and glial cells
Nervous system cells
Three structural types of neurons
Bipolar
Unipolar
Multipolar
Three functional types of neurons
Sensory input
Integration
Motor output

11. Unipolar A single process that extends from the cell body
Dendrite and axon are fused
Found in the peripheral nervous system
Created by the fusion of two polar processes during development.

12. Multipolar Has several dendrites Has a single axon
Found in the brain and spinal cord.

13. Bipolar Has a single main dendrite Has a single axon
Found in the inner ear, retina of the eye, and the olfactory center of the brain.

14. Sensory neurons Sensory receptor, such as those in the skin
Recieves input as a nerve impulse
Part of the central nervous system

15. Integration neurons Known as interneurons
Found in the central nervous system
Act as a link between the sensory and motor neurons

16. Motor neurons Transmit information from the central nervous system
Transmits to effectors, effectors include muscles glands, and other organs.

17. Electrochemical Impulse Aka: An Action Potential
By: Rita Kumar

18. Discovery of electrochemical impulses
Luigi Galvani (1737 – 1798)
Julius Bernstein ( )
K.S. Cole and H.J. Curtis
experimented with frogs at University of Bologna in a solution of saltwater
Proposed the membrane hypothesis (1902)
Cole and Curtis decided to test this theory
accidentally touched two different metals together
Neurons have selectively permeable cell membranes. These membranes allow for the transport of K+ and Na+ ions
Extracted neuron from a squid
results indicated electrical stimulation
At rest, the neuron has a potential difference across its membrane
tested with an electrode spanning the cell membrane
K+ flow out of the cell, resulting in a decrease of potential difference
They proved Bernstein’s hypothesis
Luigi Galvani
K.S. Cole
Julius Bernstein

19. What Does It Do For the Body?
The purpose of electrochemical impulse is to pass a stimulus-generated impulse down the neural axon to a receptor, be it another neuron or a muscle.
The passing of electrochemical impulses allows for organisms to recall, feel, think, emote, hear, see, etc.
Without proper nerve conduction, diseases such as multiple sclerosis may occur.

20. Sodium Potassium Pump
Since like charges repel, the highly positive Na+ ions repel each other, and want in the cell membrane.
The sodium-potassium pump allows these ions to cross an otherwise impermeable membrane.
3 Na+ ions move out of the membrane using the pump
2 K+ move in the membrane using the same pump
The net effect, since there are more Na+ ions outside than K+ ions inside, the cell membrane has a strong positive charge outside. The difference from the inside to the outside is -70 mV, or the resting potential.

21. Steps in an Electrotonic Potential
There are voltage gated ion channels for sodium and channels for potassium ions.
A stimulus forces a Na+ channel open.
Sodium ions flow into the cell
The voltage across the membrane will increase
When the voltage reaches its threshold potential, other voltage gated ion channels are stimulated, and they open as well
Electrotonic potentials faster than action potentials.
The effect of electrotonic potential diminishes the further down the cell you go.

22. Steps in an Action Potential
The threshold potential for an action potential is -55 mV.
The Na+ channel is forced open.
Sodium ions flow into the cell, increasing the potential across the cell greatly.
The sodium ion channels close at +40 mV
Now, the inside of the cell is more positively charged than the outside.
The potassium gate opens at +40 mV
Potassium ions flow out of the cell due to repulsive forces, decreasing the voltage
The voltage overshoots since it went lower than the resting potential.
The potassium gate closes at -80 mV.
The sodium channel is reactivated to bring the voltage back up to 70 mV.
Action potentials are “all-or-none”, that is, the voltage must reach -55 mV before it can take place.
This is an endergonic process, and is slower than the electrotonic potential, but this works better over longer axons.

23. Structure of a Neuron

24. Works Cited List

25. Signal Transmission across a Synapse
-Impulse.... Origin of stimulus--> Sensory Neurons --> Brain --> Motor Neurons --> Muscles or Glands
synapse: connection between 2 neurons or neuron & effectorExample of effector: Muscle Fibres 

26. Signal Transmission across a Synapse
Neurotransmitter: carry signal fom neuron to neuron or effector
Pre-Before Post-After

27. Signal Transmission across a Synapse
1) Action potential (A.P) arrives at end of presynaptic neuron, the impulse causes intracellular sacs (synaptic vesicles) which contain neurotransmitters to fuse to the axons membrane.  Synaptic vesicles release neurotransmitter into synaptic cleft: (space between neurons) by exocytosis

28. Signal Transmission across a Synapse
exocytosis: transport method in which vacuole fuses with cell membrane & releases contents outside cell

29. Signal Transmission across a Synapse
2) Released neurotransmitter diffuses across synapse taking ms to reach the dendrites of post synaptic neuron or cell membrane of effector

30. Signal Transmission across a Synapse
3) Contents released (the neurotransmitters) and bind to receptor proteins which polarize the post synaptic membrane and allow for Na + ions to flow through the ion channel protein into the postsynaptic channel
When the postsynaptic membrane is polarized, the threshold potential could be reached which initiates an action potential.  The impulse will travel along postsynaptic neuron to its terminal and to the next neuron or effector.  

31. Signal Transmission across a Synapse
4) Enzyme will break up the neurotransmitters in the postsynaptic neuron and its components will be reabsorbed by the presynaptic neuron.  

32. How is a Reflex Arc a Form of Feedback?
Judy Zhong

33. Overview
Definitions
The main sections of the Nervous System that are involved in the Reflex Arc
Feedback System Vs. Reflex Arc
Video

34. Definitions Reflexes: Reflex Arc: Feedback systems:
An involuntary response to a certain stimulus
Reflex Arc:
A simple connection of neurons that results in a reflex action
Feedback systems:
A cycle of events in which a variable is monitored, assessed and adjusted (used to maintain homeostasis)

35. Structure of Nervous System
Nervous System (NS)
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Sensory Pathways
Motor Pathways
Somatic Nervous System (voluntary)
Autonomic Nervous System (involuntary)
Sympathetic Nervous System
Parasympathetic Nervous System
Brain
Spinal Cord

36. Comparison Reflex Arc Negative Feedback System MHR Biology 12
Fig.8.3,pg 346 (Negative Feedback System)
Fig.8.11, pg 353 (Reflex Arc)

37. Video