The Nervous System

1. The Nervous System

2. The Nervous System • Two parts of the nervous system??

3. The Nervous System • Two parts of the nervous system?? • CNS – Central Nervous System • PNS – Peripheral Nervous System

4. Review of Neurons

5. CentralNervousSystem • Made of Two Components: • The Brain • Spinal Cord • Grey Matter – Mainly contain cell bodies • White Matter – Contain neurons covered in myelin

6. The Brain • Our brain contains around 100 Billion Neurons • Average Volume of 1.2 – 1.4 L • The Brain cannot feel pain • Information can be processed as slow as 0.5 ms-1 or as fast as 120 ms-1 • On average we have 70000 thoughts a day • There are about 160935 km of Blood vessels • Neurons develop at the rate of 250000 neurons per minute during early pregnancy

7. Brain stem • Also called the medulla • Spinal cord widens • Controls breathing, blood pressure and heart rate • Damage can be fatal • Cerebellum • Responsible for our coordination and balance

8. The Cerebrum • Occupies more than 80% of the brain. • Has many folds to increase its surface area (3x) • Where the higher intellectual functions take place: • Conscious Thought • Intentional Movement • Sensory messages from all body parts

9. PeripheralNervousSystem • There are two parts to our peripheral nervous system.

10. PeripheralNervousSystem • There are two parts to our peripheral nervous system. • Somatic Nervous System • Autonomic Nervous System

11. Somatic Nervous System • Collect information about Stimuli from sensory organs (Receptors). • Examples of Receptors?? • Example of Stimuli for each?? • Coordinates movement

12. Somatic Nervous System • Collect information about Stimuli from sensory organs (Receptors). • Examples of Receptors?? • Ear, Skin, Eyes, Tongue • Example of Stimuli for each?? • Temperature, Light, Touch, smell and sound

13. Our Sense of Sight • One sixth of our eyes are visible • Pupil is the opening that allows the light to enter the eye • The lens bends the light (Refracts) the light to focus the light rays onto the photoreceptors in the retina • Two types of Photoreceptors: Cone and Rod cells

14. Our Sense of Sight

15. Our Sense of Sight • Rod Cells: • Work in dim light • Responsible for night vision • Cone Cells: • Work in bright light • Responsible for Colour • Colour Blindness • Can have fewer cone cells, or have certain types of cells missing • Fovea • Contains a high concentration of cone photoreceptors • Responsible for Sharp Central Focus (detail) (reading, watching, driving)

16. Our Sense of Hearing • Numerous Receptors are grouped together to form the Ear. • Not only detects sounds • Assists with balance.

17. Our Sense of Hearing

18. Our sense of Smell and Taste • The two senses are linked. • Chemoreceptors • Taste – Taste Buds • There about 10000 of these spread across your tongue • Olfactory Bulb

19. Our sense of Smell and Taste

20. Our sensitive Skin • Responds to varied stimuli. • Heat • Touch • Pain • Cold • Pressure • Hair movement

21. Summary • Review of Neurons - Neurons • Components of the CNS • Structure of the Brain • Components of the PNS • Our Sense of Sight • Our Sense of Hearing • Our sense of Smell and Taste • The different senses of our Skin • Homework