Nervous System Ch. 49

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Nervous SystemCh. 49
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• 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.

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Ch. 49.1 Neurons Nerve Impulses

• Neuron Structure
• 1. dendrites
• 2. cell body (nucleus)
• 3. axon (axon terminals)
• 4. synapse (gap)
• 5. neurotransmitters

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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.
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• Neurotransmitters

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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)

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Ch. 49.2 Structures of the Nervous System
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External Brain

• Cerebrum
• -two cerebral hemispheres
• -corpus callosumheavy band of nerves connects
  the two hemispheres
• -area for sensory processing and motor
  responses

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Lobes of the Brain

• Frontal intellectual function, emotions
• Parietal motor and sensation
• Temporal hearing
• Occipital vision
• Cerebellum balance coordination

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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.

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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

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• Cerebellum (coordination of muscle activity)
• Spinal Cord
• sensory neurons
• motor neurons
• interneurons

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Protection for the Nervous System

• Meninges (layers)
• 1. Dura Mater
• 2. Arachnoid Layer
• 2a. Subarachnoid Space contains Cerebrospinal
  Fluid
• 3. Pia Mater

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• 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
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Peripheral Nervous System

• -afferent neurons (towards)what we call sensory
  neurons.
• -efferent neurons (away)what we call motor
  neurons.
• Two divisions Sensory and Motor.

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Division 1 Sensory

• -contains sensory receptors (nerves) and
  interneurons that connect them to the brain.

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Division 2 Motor

• -Composed of two independent systems
• 1. Somatic Nervous System
• -controls skeletal muscles
• -reflexes
• -mainly voluntary, but can be
• involuntary.

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

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Ch. 49, section 3 Sensory Systems

• Mechanoreceptors
• Photoreceptors
• Chemoreceptors
• Thermoreceptors
• Pain receptors
• Main sense organs eyes, ears, nose, mouth skin