1. Maintaining Homeostasis using the Nervous System

2. Nervous System Regulates How Respiratory System Circulatory System
Urinary System
Digestive System
Musculoskeletal System
Reproductive system
Breathing rate
Heart rate and dilation of blood vessels
Water balance
Causes muscular contractions and secretion of enzymes
movement
Secretes hormones that control development of gametes

3. Nervous System Interactions

4. Functions Receive sensory input Integrate information
Skin, other organs
Internal or external
Integrate information
Sums up info
Generate motor output
Muscle contraction
Cause glands to secrete hormones

5. Nervous System Central Nervous System Peripheral Nervous System
Brain (skull)
Spinal cord (vertebrae)
All nerves outside CNS
Sensory and motor
Both Systems must work together!

6. Nerve Cells = Neurons
Unique shape
Conducts electrical impulses

8. Synapse – small gap between nerve cells, across which impulses pass by diffusion of a neurotransmitter.

9. Resting Neuron

10. Resting Neuron (ready to respond)
Inside of Neuron
Outside of Neuron
Negative charge
More Potassium (K+) ions
Positive charge
More Sodium (Na+) ions
Polarized Membrane
Imbalance is maintained by Active Transport - Sodium Potassium Pump

11. Polarized
Na+ and K+ gates are closed

12. Action Potential Rapid change in polarity Caused by Stimulus
Na+ gates open

13. Action Potential Must reach minimum amount = threshold
Impulse is “All or none”
Membrane becomes depolarized (positive on inside)
Impulse travels in only one direction

14. After impulse - Membrane must be repolarized

15. Repolarization Sodium gates close Potassium gates open
Potassium leaves
Inside returns to negative charge

16. Activating next Neuron
Reaches end of axon
Triggers release of neurotransmitters
These chemicals diffuse across synapse
Bind to receptors on next neuron start impulse

17. Saltatory Conduction
Impulse jumps from one node (N.O.R.) to next; speeds up impulse
More myelin = faster impulse

18. Integration of Signals
Different parts of the brain regulate responses of glands and muscles

19. Each part regulates specific functions

20. Functions Cerebrum: thinking Cerebellum: coordinate movement
Medulla: breathing, heart rate, blood pressure
Hypothalamus: regulates hunger, temperature, water balance
Pineal Gland: daily rhythms
Pituitary: endocrine gland that controls other glands

21. Destroying Nervous Systems Homeostasis
Spinal cord injury – can’t be repaired
Epilepsy – neurons don’t fire correctly
Multiple sclerosis – destroys myelin sheath

22. Effects of Drugs Block receptor Activate neurotransmitters
caffeine
Activate neurotransmitters
Nicotine - dopamine
Block receptors
Novacain
Block normal breakdown of neurotransmitter
Cocaine