1. Nervous System Ch. 49

2. Nervous System 1. Central nervous system (CNS): brain and spinal cord.
2. Peripheral nervous system (PNS): cranial nerves, spinal nerves, and nerves that travel throughout the body.

4. Ch. 49.1 Neurons & Nerve Impulses
Neuron Structure: 1. dendrites 2. cell body (nucleus) 3. axon (axon terminals) 4. synapse (gap) 5. neurotransmitters

5. Neurotransmitter
Function
Acetylcholine
Muscle contraction throughout the body.
Dopamine
Emotions, regulate movement.(Parkinson's)
Endorphins
Natural painkiller, sexual stimulant, reduce stress, feeling of euphoria.
Epinephrine
Increases heart rate, constricts blood vessels, fight-or-flight response. (adrenaline)
Norepinephrine
Increases heart rate, increases breathing rate, increases blood flow to skeletal muscles.
Serotonin
Helps with sleep, ‘happy’ feeling, emotions, relieves depression.

6. Neurotransmitters

7. Nerve Impulses
Neuron function is dependent upon electrical activity: Resting Potential (Na+ out, K+ in) -neurons are in a state of waiting for a stimulus. Action Potential (Na+ in, K+ out) -dendrites or cell body become stimulated. -ATP driven sodium-potassium pump re-establishes equilibrium (restores the ions to be ready for another action potential)

8. Ch. 49.2 Structures of the Nervous System

9. External Brain Cerebrum -two cerebral hemispheres
-corpus callosum…heavy band of nerves; connects the two hemispheres
-area for sensory processing and motor responses

10. Lobes of the Brain:
Frontal: intellectual function, emotions Parietal: motor and sensation Temporal: hearing Occipital: vision Cerebellum: balance & coordination

11. Diencephalon
1. Thalamus: -directs incoming sensory & motor signals to the proper area of the cerebrum. -regulates consciousness, sleep, and alertness. 2. Hypothalamus: -maintains homeostasis. -controls hormone production. -controls anger & aggression.

12. Brain Stem: (links cerebrum with the spinal cord)
1. Midbrain: relays visual, auditory, motor, alertness, and temperature regulation. 2. Pons: relays info between cerebral hemispheres and the cerebellum. 3. Medulla Oblongata: heart rate, breathing rate, blood pressure. Video Clip

13. Cerebellum: (coordination of muscle activity) Spinal Cord: sensory neurons motor neurons interneurons

14. Protection for the Nervous System
Meninges (layers)
1. Dura Mater
2. Arachnoid Layer
2a. Subarachnoid Space: contains Cerebrospinal Fluid
3. Pia Mater

15. Divisions of the Nervous System
Peripheral Nervous System
Central Nervous System
Sensory Motor
Somatic NS
Autonomic NS
brain and spinal cord
Regulates activities under conscious control
Regulates activities that are automatic
Parasympathetic – slows down activities
Sympathetic – Speeds up activities

16. Peripheral Nervous System
-afferent neurons (towards)…what we call sensory neurons. -efferent neurons (away)…what we call motor neurons. Two divisions: Sensory and Motor.

17. Division 1: Sensory
-contains sensory receptors (nerves) and interneurons that connect them to the brain.

18. Division 2: Motor 1. Somatic Nervous System
-Composed of two independent systems:
1. Somatic Nervous System
-controls skeletal muscles
-reflexes
-mainly voluntary, but can be
involuntary.

19. 2. Autonomic Nervous System
-Controls smooth muscles in blood vessels and organs; respiration, heartbeat and other homeostatic functions
-Two Divisions:
1. Sympathetic (stress…moves blood to appropriate organs based upon the stressor.
2. Parasympathetic (normal)

20. Ch. 49, section 3: Sensory Systems
Mechanoreceptors Photoreceptors Chemoreceptors Thermoreceptors Pain receptors Main sense organs: eyes, ears, nose, mouth & skin