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Identify the principle parts of the nervous system
Describe the cells that make up the nervous system
Describe what starts and stops a nerve impulse (action potential)
The role of neurotransmitters Compare the functions of the CNS & PNS Identify the principle parts of the brain
Objectives
CNS = spinal cord & brain PNS = nerves carry (tissue) impulses to and
from brain Motor Output side of chart has 2 divisions:
somatic and autonomic Focus Somatic 1st then Autonomic
Requires only one neuron system: CNS to cell 12 pairs cranial nerves
◦ From brain’s underside/brain stem◦ Brain to muscles, glands, head, neck, thorax,
abdomen 31 pairs spinal nerves
◦ Originate from spinal cord◦ Dorsal root ganglia– sensory incoming AP from
tissues to cord◦ Ventral root ganglia– motor outgoing AP away from
cord to body Connects CNS to body parts
Somatic division/Motor/PNS
Spinal Reflexes – require no conscious thought – processes @ spinal cord only
E.g. flexor reflex – withdrawal of foot from something sharp
Knee-jerk reflex (check up) – tap below patella causes contraction of thigh and upward movement of foot and leg
Stretch (quadriceps) reflex – posture maintenance – stand and move w/out having to think about it
Reflexes
Sympathetic – stress / high activity Parasympathetic – resting, homeostasis 2 neuron system to transmit impulses to
target cells 1st neuron - preganglionic in CNS 2nd neuron – postganglionic outside CNS &
extending to the far reaches of the body (glands/organs)
Sympathetic & Parasympathetic oppose each other – work antagonistically for homeostasis
Autonomic Division
Neurotransmitters◦ Sympathetic – norepinephrine (adrenalin) - stress◦ Parasympathetic – acetylcholine - relax
Sympathetic vs. Parasympathetic
Central location & action
Integrating & processing of information
Info in CNS Complex Output
Brain & Spinal Cord
“Billions of action potentials travelling in millions of neurons all come together as a conscious thought”
Reflexes and the reflex arc – terms 142-143 Learning Target #5 (Nervous System) p 135:
Describe the structure of a reflex arc and the function of a reflex
Assignment 3.23
Bone, meninges & blood-brain barrier Bone: skull & hollow vertebrae Meninges: CNS enclosed by 3 membranous
layers◦ Out In◦ Dura matter – arachnoid matter – pia matter
Protection of CNS
CNS is bathed in cerebrospinal fluid Fills the space between the arachnoid
matter & pia matter
Functions as a liquid shock absorber
Isolates the CNS from infection (meningitis: bacterial or viral infection of meninges can spread to CNS)
CNF (cerebrospinal fluid)
CSF is like the interstitial fluid that bathes all cells but it does not exchange substances as freely with blood
Capillaries in this area are “tight” = not leaky & substances must pass through the actual capillary cells (vs. slipping between narrow slits of adjacent capillary cells) to get from blood to the brain
More about CSF
Lipid soluble substances pass easily (O & CO2)
Glucose requires active transport Larger molecules: proteins, viruses,
bacteria kept out What can pass through BBB?
◦ Alcohol◦ Caffeine◦ Nicotine◦ Cocaine◦ Anesthetics
Blood-brain barrier
Information super highway for APs between the brain and the body
Recall – spinal reflexes don’t involve brain and therefore are considered “unconscious”
Size – about the diameter of your thumb
Location – runs from the base of your skull to the area of the 2nd lumbar vertebra ~ 17 inches
Spinal cord
Outer portions of the cord consist of bundles of axons = nerve
tracts that are mylenated = white matter – ascending sensory nerves & descending motor nerves
Inner portions consist of cell bodies, dendrites, neuroglial cells
that are unmylenated = gray matter – here sensory & motor neurons synapse & transmit to the brain…
Inside the spine
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