Nervous System Unit 5 Structure Central Nervous System
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Nervous System Unit 5
Structure Central Nervous System (CNS): brain and spinal cord. Peripheral Nervous System (PNS): nerves of the body -- Includes 31 pairs of spinal nerves -- And 12 pairs of cranial nerves
Structure Somatic Nervous System - skeletal (voluntary) Autonomic Nervous System - smooth muscles, glands (involuntary)
Basic Divisions of the Nervous System Figure 12. 2
Structure A. Neurons = masses of nerve cells that transmit information 1. Cell Body - contains the nucleus and two extensions 2. Dendrites – shorter, more numerous, receive information 3. Axons – single, long “fiber” which conducts impulse away from the cell body, sends information
• Chromatophilic substance (rough ER) - transport system • Myelin -insulation surrounding axons • Nodes of Ranvier - gaps in the insulation
Neuroglial Cells - support cells for the neurons 1. Microglial Cells: scattered throughout, digest debris or bacteria
Neuroglial Cells 2. Oligodendrocytes: provide insulation around the axons
Neuroglial Cells 3. Astrocytes: connect blood vessels to neurons
Neuroglial Cells 4. Ependymal Cells: form a membrane that covers brain-like parts
Neuroglial Cells 5. Schwann cells: form the insulating myelin sheath around the neurons
Supporting Cells- NEUROGLIA
Functions • Sensory - gathers info • Integrative - information is brought together • Motor - responds to signals, homeostasis
Interesting Facts about the Neuron • Longevity – can live and function for a lifetime • Do not divide – fetal neurons lose their ability to undergo mitosis; neural stem cells are an exception • High metabolic rate – require abundant oxygen and glucose
Communication Synapse - junction between two communicating neurons Nerve pathway - nerve impulse travels from neuron to neuron Synaptic Transmission Dendrite ->cell body -> along axon -> synapse (gap) To complete the signal, a NEUROTRANSMITTER is released at the gap to signal the next neuron
Communication Excitatory - increase membrane permeability, increases chance for threshold to be achieved Inhibitory - decrease membrane permeability, decrease chance for threshold to be achieved.
Neurotransmitters • Acetylcholine - stimulates muscle contraction • Monoamines - Norepinephrine & Dopamine (sense of feeling good, low levels = depression) • Serotonin (sleepiness) • Endorphins (reduce pain, inhibit receptors)
Communication These neurotransmitters allow the nervous system to communicate with all systems throughout the body. This allows the body to maintain homeostasis.
Neuronal pool - groups of neurons that make hundreds of synaptic connections and work together to perform a common function.
Types of Nerves Sensory Nerves - conduct impulses into the brain or spinal cord Motor Nerves - carry impulses to muscles of glands Mixed Nerves - contain both sensory and motor nerves
Nerve Pathways • • Reflex arc - only includes a few neurons Reflex Behavior - automatic, subconscious responses Knee-jerk reflex - maintains uprightness Withdrawal reflex - avoidance of painful stimuli
- Identify each type of neuronal pool
- Fundamentals of the nervous system and nervous tissue
- Nerve cell process
- Major division
- Central nervous system amusement park
- Central. nervous system
- Nervous system vocabulary
- Central and peripheral nervous system
- Central auditory nervous system
- Part of nervous system
- Central nervous system for kids
- Basic unit of nervous system
- Blood clot feedback loop
- Subthalamus
- Structure of nervous system graphic organizer
- Nervous system structure
- Central nervous sysytem
- Unit 10, unit 10 review tests, unit 10 general test
- Nervous system and digestive system
- Endocrine system vs nervous system
- Nervous system vs endocrine system venn diagram
- Adh function