Nervous System Ch. 49. Nervous System -Found in every part of the body from the head to the tips of...
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Transcript of Nervous System Ch. 49. Nervous System -Found in every part of the body from the head to the tips of...
Nervous SystemCh. 49
Nervous System-Found in every part of the body from the head to the tips of the fingers and toes. -Divided into central nervous system (CNS) and peripheral nervous system (PNS).-CNS contains brain and spinal cord.-PNS contains cranial nerves, spinal nerves, and nerves that travel throughout the body.
Ch. 49.1 Neurons & Nerve Impulses
Neuron Structure:1. dendrites2. cell body3. axon (axon terminals)
4. synapse5. neurotransmitters
Neurotransmitters
Nerve ImpulsesNeuron function is dependent upon electrical activity:
Resting Potential
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)
Ch. 49.2 Structures of the Nervous System
BrainFunction
Structure:1. Cerebrum
two cerebral hemispheres
cerebral cortex…sensory processing and motor responses.
corpus callosum…heavy band of nerves; connects the two hemispheres
white matter…contains axons of cortical neurons.
Lobes of the Brain:
Frontal: intellectual function
Parietal: motor and sensation
Temporal: taste & hearing
Occipital: vision
Cerebellum: balance & coordination
Diencephalon
1. thalamus (directs incoming sensory signals to the proper region of the cerebral cortex)
2. hypothalamus (maintains homeostasis, hormone production)
Limbic System: structures within the brain that control emotions, memory, and motivation.
3. Brain Stem: (links cerebrum with the spinal cord)
1. midbrain (relay center for visual & auditory information)
2. pons (relay center between cerebral hemispheres and the cerebellum )
3. medulla oblongata (heart rate and respiration)
-reticular formation (network of neurons helping to control respiration and circulation and serves as a filtering system for incoming sensory signals.
4. cerebellum: (coordination of muscle activity)
5. spinal cord: sensory neuronsmotor neuronsinterneurons
Divisions of the Nervous System
Central Nervous SystemPeripheral Nervous System
brain and spinal cord Somatic NS Autonomic NS
Regulates activities that are automatic
Regulates activities under conscious control
Parasympathetic – slows down activities
Sympathetic – Speeds up activities
Sensory Motor
Peripheral Nervous System
-afferent neurons (towards)…what we call sensory neurons.
-efferent neurons (away)…what we call motor neurons.
Two divisions: Sensory and Motor.
Division 1: Sensory
-contains sensory receptors (nerves) and interneurons that connect them to the brain.
Division 2: Motor
-Composed of two independent systems:
1. Somatic Nervous System
-controls skeletal muscles-reflexes-mainly voluntary, but can be involuntary.
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)
Ch. 49, section 3: Sensory Systems
MechanoreceptorsPhotoreceptorsChemoreceptorsThermoreceptorsPain receptors
Main sense organs: eyes, ears, nose, mouth & skin