1. The Nervous System
35-2 & 35-3

2. What do YOU see here?

3. By the end of this lesson you should be able to:
Identify the parts and functions of the nervous system
Identify and label the parts of the brain and a neuron
Describe how a nerve impulse is transmitted

4. Function of the Nervous System:
Body communication
Controls and coordinated body functions
Responds to internal and external stimuli
Carries messages (electrical impulses) along nerve cell called neurons

5. Two Main Parts of the Nervous System
Central Nervous System (CNS) - the control center of the body; consists of the brain and spinal cord
Relays messages
Processes information
Analyzes information
Peripheral Nervous System (PNS) - receives information from the environment and sends commands from the CNS to the organs and glands

6. Protection for the CNS Skull and vertebrae
Meninges - three layers of connective tissue that wrap the brain and spinal cord
Cerebral spinal fluid - fluid surrounding the brain and spinal cord that acts as a shock absorber; also allows for nutrients and wastes to be exchanges

7. The Brain

8. Parts of the Brain Cerebrum -
Largest part composed of folds and grooves that make up the four major lobes
Responsible for voluntary activites
Site of learning, intelligence, and judgement
Left side (hemisphere) controls that right hand side of your body and the reverse
Consists of two layers (1) outer cerebral cortex made of only grey material and (2) inner white matter

9. Parts of the Brain Cerebellum - Brain Stem -
Second largest brain region
Found at the back of the skull
Coordinates and balances muscle movement
Brain Stem -
Connects the brain to the spinal cord
Contains the pons and medulla oblongata
Responsible for blood pressure, heart rate, breathing…

10. Parts of the Brain The Hypothalamus The thalamus -
Recognizes hunger, thirst, fatigue, anger, and body temperature
Coordinates the nervous and endocrine system
The thalamus -
Receives sensory messages and sends them to the cerebrum

11. Spinal Cord
Contains 31 nerves that connect the brain to the rest of the body
Processes certain reflexes - quick automatic response to a stimulus like blinking

12. Peripheral Nervous System
Sensory Division - transmits impulses from the sense organs to the CNS
Motor Division - transmits impulses from the CNS to muscles or glands composed of:
Somatic Nervous System
Autonomic Nervous System

13. The Somatic Nervous System
Deals with activities that are under your conscious control
Ex: Moving your pen, poking your neighbor, and reflexes

14. Reflexes Rapid responses
Follow a modified path so they do not need to go all the way to the brain before a response is produced
Reflex arc - includes a sensory neuron, a motor neuron, and an effector (muscle)

15. The Autonomic Nervous System
Responsible for involuntary, automatic movements

16. The Autonomic Nervous System
Sympathetic division – responsible for “fight or flight response”; speeds things up like heart rate & increases blood pressure
Parasympathetic division – opposes the sympathetic to slow things down and return to normal

17. Sensory Receptors Bonus Material
Pain receptors - respond to chemicals released by damaged cells so the body can recognize danger
Thermoreceptors - detect variations in temperature
Mechanoreceptors - sensitive to touch, pressure, sounds, motion and muscle stretching
Chemoreceptors - sensitive to chemical in the external environment
Photoreceptors - sensitive to light

18. Homework
Complete filling in your Nervous System Chart in your topic packet
Worksheets pages
BONUS STUDY WEBSITES:
Drugs and the Brain
The Brain

19. Back to the impulse…

20. Types of Neurons:
Sensory neurons - carry impulses from the sense organs to the brain and spinal cord
Motor neurons - carry impulses from the brain and spinal cord to the muscles and glands
Interneurons - connect sensor and motor neurons

22. Structure of Neurons
Label these parts and make sure they are defined in your vocabulary section

23. What do neurons do? Transmit nerve impulses
Relies on electrical charges
Uses Sodium (Na+) and Potassium (K+) to create a charge difference between the nerve cell and its outer environment

24. The Neuron in Action
Check out what is happening here!

25. 1) Resting State of a Neuron
Resting Potentail
The Sodium (Na+) - Potassium (K+) pump maintains a net negative charge on the inside of the neuron
The Pump

26. Sodium Potassium Pump- Resting State
3 Na+ Out
2 K+ In
___________
Net Charge = ?

27. 2-3) Action Potential/Nerve Impulse
An outside stimulus creates a nerve impulse that travels down the axon away from the cell body
The inside of the nerve cell is temporarily more positive - Sodium (Na+) flow into the nerve cell

28. 4-5) Action Potential
Behind the impulse, K+ flows out restoring the negative
The impulse leaves through the terminal and transmits to neighboring dendrites

31. How does a neuron “know” to send an impulse?
A nerve will only transmit an impulse if the initial stimulus that is picked up at the dendrites is larger than the threshold
Threshold - the lowest level of stimulus that will create an impulse; all-or-none response
If the stimulus is weaker than threshold NO IMPULSE will be produced

32. The Nerve Impulse
What does it look like?

33. The Synapse Occurs between one axon and its neighboring dendrite
Relies on chemical called neurotransmitters