2 .2

1. 2.2 THE NERVOUS SYSTEM

2. The body’s communication systems help maintain homeostasis. • A stimulus causes a response. • Responses can be chemical, cellular, or behavioral. • The nervous system responds to stimuli.

3. The nervous system controls thoughts, movement, and emotion.

4. spinal chord nerves • The nervous system works quickly, using chemical and electrical signals. • interconnected network of cells • signals move through cells • divided into central nervous system (CNS) and peripheral nervous system (PNS)

5. The nervous system’s two parts work together. • The CNS includes the brain, brain stem, and spinal cord. • The PNS includes four systems of nerves.

6. The CNS processes information. • The brain has three parts. • cerebrum controls thought, movement, emotion

7. Lobes of the Brain There is a fifth lobe, known as the limbic lobe, that is responsible for emotions

8. midbrain Brainstem pons medulla oblongata The CNS processes information. • The brain has three parts. • cerebrum controls thought, movement, emotion • cerebellum allows for balance • brain stem (reptilian brain) controls basic life functions

9. midbrain pons medulla oblongata • midbrain controls some reflexes • pons regulates breathing • medulla oblongata controls heart function, swallowing, coughing • The brain stem has three parts.

10. interneuron motor neurons sensory neuron • sensory neuron sends impulse to spinal cord • spinal cord directs impulse to motor neuron • does not involve the brain • See simulation with online textbook • The spinal cord controls reflexes.

11. The PNS gathers and transmits information • links the CNS to muscles and other organs. • The somatic nervous system regulates voluntary movements.

12. The PNS gathers and transmits information • The autonomic nervous system controls involuntary, functions • sympathetic nervous system: • “fight vs. flight” • Involved in all internal adjustments that prepares the body for action or increased levels of stress. • parasympathetic nervous system: • sends impulses that return a body to “normal” functioning after a period of stress is over, • conserves energy

13. Fine adjustments made so glands and organs are functioning at levels appropriate to a body at a particular time:

14. Sensory receptor generates impulse. • PNS passes impulse to CNS. • CNS interprets impulse. • CNS passes impulse to PNS. • PNS stimulates a response. • The CNS and PNS pass signals between one another.

15. Sensory Input triggered by stimuli • conduction of signals to processing center • Integration • interpretation of sensory signals within processing centers • Motor output • conduction of signals to effector cells (i.e. muscles, gland cells) Basic Organization sensory receptor (sensory input)  integration  (motor output)  effector

16. Nerves • Nerves, which carry the electrical impulses to various parts of the nervous system, are made up of a bundles of cells, known as neurons

17. Cell body 1 Neurons are highly specialized cells. • A neuron has 3 main parts. • cell body contains nucleus and organelles

18. 2 dendrites Neurons are highly specialized cells. • A neuron has three parts. • cell body has nucleus and organelles • dendrites receive impulses

19. 3 axon Neurons are highly specialized cells. • A neuron has three parts. • cell body has nucleus and organelles • dendrites receive impulses • axoncarries (transmits) impulses

20. Schwann cell makes up the myelin sheath, which insulates the axon • Neurons have other structures to transmit signals.

21. Schwann cell makes up the myelin sheath, which insulates the axon • Nodes of Ranvier – the gaps between the myelin sheath that speed up the process of transmitting impulses. • Neurons have other structures to transmit signals.

22. Schwann cell makes up the myelin sheath, which insulates the axon • Nodes of Ranvier – the gaps between the myelin sheath that speed up the process of transmitting impulses. • Neurons have other structures to transmit signals. • Axon terminal – part through which the impulse leaves. axon terminal

23. synapse • Schwann cell makes up the myelin sheath, which insulates the axon • Nodes of Ranvier – the gaps between the myelin sheath that speed up the process of transmitting impulses. • Neurons have other structures to transmit signals. • Axon terminal – part through which the impulse leaves. • synapse gap between the neuron and the next cell.

24. Types of Neurons • Sensory Neuron: detect stimuli and transmit signals to the brain and the spinal cord, which are both made up of interneurons. • Interneurons: receive signals from sensory neurons and relay them within the brain and the spinal cord. Process information and pass signals to motor neurons. • Motor neurons: pass messages from the NS to other tissues in the body, such as muscles