1. The Nervous System

2. Regulation The control and coordination of life activities
All organisms use chemicals to regulate life activities
Multicellular animals have NERVE CONTROL
Allow for organisms to maintain HOMEOSTASIS

3. Stimuli are detected by RECEPTORS
Stimulus:
Any change in the external or internal environment that initiates a RESPONSE
Response:
A change in BEHAVIOR
Stimuli are detected by RECEPTORS
Sensitive to a particular type of stimulus
Ex. EyesLight, EarsSound
Effectors:
Organs that produce a response to a stimulus
Ex. Muscles and Glands

4. Neuron
Specialized cells which are responsible for transmitting IMPULSES from one part of the body to another
Impulse:
Electrical and chemical changes that travel through neurons
Causes the release of NEUROTRANSMITTERS from terminal branches
**Neuron-Nerve-Ganglia-Brain
Made up of 4 main parts

5. Dendrites (Receptors)
Cell branches that receive impulses from other neurons or from receptors

6. Cyton
The cell body
Contains a nucleus

7. Axon
The branch of the cell that transmits impulses away from the cyton

8. *Node of * Schwann Cell * Myelin Myelin Sheath
The fatty insulation covering produced by the Schwann cells.
Nodes of Ranvier – Area of no myelin
*Node of
Ranvier
* Schwann Cell
* Myelin

9. Terminal Branches Responsible for:
transmitting impulses to the dendrites of other neurons
Transmitting impulses to effectors

10. Synapses Junction between adjacent nerve cells
Some nerve cells have junctions with muscles or glands
Chemicals released stimulate contraction of the muscle, or secretion by the gland

11. Neurotransmitters
Chemicals that are secreted by the terminal branch into the synapse between neurons
Carry impulses from one cell to the next
Ex. Acetylcholine and Noradrenaline

12. Amoeba – No true nervous system Paramecium
System of FIBRILS that transmit impulses to cilia
Regulates LOCOMOTION and INGESTION
Some species of Protozoans have EYESPOTS
Receive stimuli and generate impulses to produce a response
Hydra
Contain specialized cells similar to neurons, but do not have a central nervous system
Cells connect to form a NERVE NET
Impulses travel in any direction

13. Earthworm
Has neurons organized into distinct structures and organs which form a TRUE NERVOUS SYSTEM
Brain:
Mass of ganglia located on the dorsal side of the worm, near the head
Ventral Nerve Cord
Main nerve
Connected to the brain and runs along the length of the animal on the ventral side (Belly)
Nerve Branches
Series of smaller nerves that branch to all parts of organism
Impulses are generated by receptors and travel through the nerves to reach muscles and glands

15. Grasshopper Similar nervous system to earthworm Has SENSORY ORGANS
Eyes
Tympanum- Detects sound
Antennae- Sense and Touch

16. A Lateral view B Dorsal view 1 Antenna 2 Brain (cerebral ganglion) 3 Compound eye 4 Tympanum 5 Ganglion 6 Beginning of the Dorsal Nerve Cord 7 Segmental nerves 9 Ventral nerve cord

17. Human Nervous System Concept Map
Central Nervous System
Peripheral N.S.
Brain
Spinal Cord
Communication between the brain and the P.N.S.
Cerebrum
Controls all conscious thought
Cerebellum
Balance and coordination
Medulla
Involuntary control
Heart, Respiration, Organs

18. Cerebrum
Medulla

19. Human Nervous System Concept Map
(Central Nervous System)
Peripheral N.S.
Involuntary (Autonomic)
Visceral (Organs)
2 Parts
Voluntary
(Somatic)
Control of all skeletal muscles
Fight or Flight
Parasympathetic
Control of the organs
Designed to decrease function
(Acetylcholine)
Calming effect
Sympathetic
Control of the organs
Designed to increase function
(Noradrenaline, Norepinephrine)

21. Human Behavior
Involuntary Behavior – occurs automatically without conscious control
Inborn – present at birth
Acquired behavior – develops after birth as the result of experience
Walking, writing, speech
a. Simple reflex arc
b. conditioned behavior
1. automatic behavior that is acquired (habits)
2. once pathways are established, the actions are
very rapid and automatic
2. Voluntary Behavior – conscious behavior that uses the Cerebrum of the brain
Makes use of memory

22. The Reflex Arc is a real “No Brainer”
Advantages
1. speed and protection from harm and injury

23. Malfunctions of the Nervous System
Meningitis
a. inflammation of the meninges (coverings of the brain and spinal cord)
b. can be bacterial of viral
c. first signs are severe neck stiffness and headaches
2. Cerebral Palsy
a. damage to the motor centers of the brain
b. you see poor coordination (scissors gait)
3. Stroke
a. damage of the nerve cells of a region of the brain
b. due to hemorhage or blood clot