1. The Nervous System

2. What is the Nervous System?
System that controls your body and is responsible for communication between all of its parts!

3. Central Nervous System
CNS- brain and spinal cord

4. Peripheral Nervous System
PNS- all nerves outside the brain and spinal cord; connects CNS to rest of body.

5. Neuron Nerve cell Basic unit of the nervous system
Neurons send chemical messages to other neurons (really quickly!)

6. Synapse Neurons don’t touch! Synapse- space between 2 neurons
Messages are transferred by chemicals jumping across the gap

7. Types of Neurons
Sensory Neurons – receive sensory info from environment and send it TO brain or spinal cord.
Interneurons – receive message from SN in brain and spinal cord, and decide what to do with the message (react? or not?)
Motor Neurons – if a reaction is needed, these carry reaction message away from the brain towards muscles.

8. Stimulus Examples * Stimulus – Step on nail * Response – Jerk foot up
Anything that causes a response
Examples
* Stimulus – Step on nail
* Response – Jerk foot up
* Stimulus – See bright light
* Response – Squint Eyes

9. What is a reflex? Involuntary, automatic responses to stimuli
Controlled by spinal cord! (not brain)
Leaving out the brain enables the body to react faster

10. Basic Reflex Arc

11. Your Brain…
Has 3 main regions:
Cerebrum
Cerebellum
Brainstem

12. Cerebrum (sa-REE-brum)
Largest portion of brain
Controls sensory perception, language, memory, emotions, and learning

13. Cerebellum (sa-rah-BELL-um)
Coordinates movement
Controls balance
Controls muscle coordination
Everyday movements (eat, walk, talk, drink, write)
Damage to this area may affect movement or coordination

14. Brainstem (located underneath cerebrum)
Functions: all body processes necessary for survival!
Breathing
Digestion
Heart rate
Blood pressure
Staying awake and alert

15. The Integumentary System

16. What is the largest organ in your body?
YOUR SKIN!
Your skin weighs 10 pounds…the thinnest skin on your
body is your eyelids…the thickest is on your heels

17. The Integumentary System consists of:
hair
skin
nails
sweat glands

18. This system is responsible for:
Protecting the underlying tissue
Regulating internal body temperature
Collecting sensory information from the environment
Producing some vitamins
Retaining necessary fluids
Eliminating some wastes

19. SO WHAT’S IN YOUR SKIN?
Quite a lot! YOUR SKIN HAS THREE MAIN LAYERS all with different functions:
The epidermis
The dermis
3. The subcutaneous
tissue

20. The Epidermis Thin outer layer of skin
Top layer consists of layers of dead skin cells!
Contains keratin, which makes your skin tough and waterproof
Contains melanin, a pigment that gives skin its coloring
Melanin also absorbs UV rays from the sun and acts as a natural sunscreen
Less Melanin = More likely Skin Cancer

21. The Dermis ALSO contains Blood vessels Muscle fibers Sweat glands
Thick middle layer
Composed of collagen and elastin which allows skin to stretch
What happens to our elastin fibers as we age?
ALSO contains
Blood vessels
Muscle fibers
Sweat glands
Hair follicles

22. Subcutaneous Layer Underneath the dermis
Functions as a shock absorber, insulator, and a connector (skin to underlying organs)

23. Structures that Help the Integumentary System
hair
Blood vessels
Glands
Sweat and oil
Hair (protects & insulates the body)
Nails (filled with Keratin)
Oil gland
Muscle tissue
Sweat glands

24. It is also the reason your house is full of dust
The integumentary system is the reason crime scenes are packed with evidence….Hair! Skin! Fingerprints!
It is also the reason your house is full of dust
Dust is composed of discarded human skin among other things