AP4284 Medical Physics II

Nervous SystemStructure of the Nervous System

-Central Nervous System (CNS)Brain &Spinal Chord

-Peripheral NS (PNS) Somatic NS, Skeletal Muscles, exterior sensory organs

Autonomic Nervous System, Smooth Muscles (involuntary)

Sympathetic NS, “Fight or Flight’ // Parasympathetic NS, Non-emergency situations

Neuron, Propagation of electric signal, unidirectional

Dendrite, conduct nerve impulses towards cell body

Cell Body &Axon, conduct nerve impulses away cell body

Myelin Sheath, Schwann cell, cover long fiber, exposing space, Nodes // Ranvier

Synapses, transfer information, neurotransmitters, on dendrites &body

Motor Neurons, stimulate muscle cell, heart, diaphragm, intestines, bladder &glands

Sensory Neurons, Sense organ Message CNS, Skin, Muscles, Joint &Organs

Pressure, Temp &Pain, more in nose &tongue, sensitive molecular shape, taste &smell

Inner ears, vibration, sound // rod &cone, retina, light, see

Interneurons, connection, sensory &motor neurons, CNS, brain

Neuron package, bodyganglion, axonnerve, brain &spinal cordwhite/grey matter

Reflex arc, sensory neuron directly connect motor neuron in spinal cord, response time↓

Spinal cord, 31 pair, spinal nerves, transmission of neural signal, brain btw body

Peripheral NS, long dendrites &axon, bodies in brain, spinal cord &ganglia, dorsal

&ventral root

Somatic NS, Musculoskeletal system, effectors, react to stimulus

Exterior sense organs, receptors, receive environmental stimuli &begin nerve impulses

Autonomic NS, motor neurons, control internal organ,

Sympathetic NS, emergency situation, energy directed away from digestion, pupils

dilate, heart rate↑, perspiration↑,salivation↓, breathing rate↑

Parasympathetic NS, “rest and repair”, pupils contract, energy diverted for digestion of

food, heart rate slow