Ch 9 Nervous System Flashcards
CNS organs
Brain and spinal cord
Protected by skull and vertebral colum
Brain
Brain stem
Cerebellum
Diencephalon
Cerebrum
Spinal cord
Gray matter-unmyelated axons and dendrites
White matter-myelated bundles of axon
Peripheral nervous system PNS
3 functional divisions
Somatic nervous system -motor nerves
Sensory nerves-they sense/feel things
ANS autonomic nervous system
Autonomic nervous system
A subdivision of peripheral nervous system
Extending to outlying parts of body
Structure’s that regulate involuntary/automatic functions such as heart rate, contractions of the stomach and intestines
Primary function of the nervous system
Controls cells in the body in coordination with the endocrine system transmits info rapidly via nerve impulses
Controls other body systems integrate information
Coordinates the body cells and systems to maintain homeostasis
(PNS) 31 pairs of spinal nerves between vertabrae
Conduct impulses necessary for sensation and voluntary movement
8- cervical spine
12-thoracic
5-lumbar
5-sacral
1-coccyx
(PNS) Dermatomes
Skin surface areas that are supplied by a single spinal nerve
Sympathetic nervous system Sub division of ANS
Sub division of ANS
Fight or Flight
Functions as an emergency system
When we exercise strenuously
when strong emotions anger, fear, hate are exhibited impulse of sympathetic fibers take control of many internal organs
The heart beats faster, blood vessels constrict, causing blood pressure to increase. Blood vessels in skeletal muscles dilate.(supplying muscles with more blood)
Sweat glands and adrenal glands secrete more. salivary and other digestive glands secrete more sparingly.
peristalsis becomes sluggish hampering digestion
This involves many organs
parasympathetic nervous system
Subdivision of ANS
Dominates under normal every day conditions/Normal every day visceral functions (at peace)
Counter balances the sympathetic system
Sub division of the ANS
your heart beat slows down
peristalsis increases
there’s an increase in secretion of digestive juices and insulin
Structures of the autonomic nervous system
Motor neurons Conduct impulses from the CNS to visceral effectors(following kinds of tissues)
Cardiac muscle
Smooth muscle
Glands
(PNS) 12 pair of cranial nerves
Attached to the underside of the brain
Connect the brain with: face and neck
Some structures of the thorax(chest) and abdomen
Shingles
Viral infection caused by same virus that causes chicken pox painful rash
Shingles will follow linear pattern
It is attached to nerves
Automatic nervous system/ Autonomic
Functions
Regulates the body’s automatic involuntary functions in ways that:
maintains homeostasis
OR QUICKLY RESTORES HOMEOSTASIS
Many internal organs are dually innervated by the ANS in other words they receive fibers from both the parasympathetic and the sympathetic divisions
Bolded. Meditation
Decreased sympathetic activity
Creates a group of changes to oppose fight or flight response
Cells of the nervous system (Needed to perform life)
Neurons: nerve cells carry/conduct impulses
Glia: (glue) holds cells together and protects/supports them
Holds neurons together
Glioma: common brain CA
Sensory neurons
Afferent neurons: carry impulses TO brain and spinal cord
Sense detect or feel things
Motor neurons/ efferent neurons
Efferent neurons: Exiting brain and spinal cord
Move things: chewing and swallowing
Muscles and hormones
Can be Automatic or involuntary
Conduct impulses to muscles and glands
Interneurons
Conduct impulses from sensory to motor neurons
Or amongst connecting interneurons
3 Main parts of a Neuron
Dendrites: branching projections that conduct impulses to cell body
Cell body
Axon: enlongated projection that conducts impulses away from cell body
Peripheral neuron cell
Myelin insulation (Schwann cell)
Stimulus/ response
Astrocytes (hedden mentioned)
Form blood/brain barrier
Microglia (hedden mentioned)
Smaller than astrocytes
Structure of a neuron. MYELIN
Myelin is wrapped around the axon
Not every axon has myelin
Segmented
Multiple sclerosis is a myelin disorder
Structure of a neuron. Schwann cells (type of peripheral glia)
Form the myelin sheath in the PNS
Nodes of Ranvier
Gaps between adjacent Schwann cells
Reflexes aka reflex Arcs
Reflex are like one way streets
They allow impulse conduction in only one direction
Nerve impulsegoes from receptor to effector
Effectors create the INVOLUNTARY effect: muscles and glands
A nerve impulse/action potential on a reflex arc results in a reflex
(knee jerk)
2- neuron reflex arc
Simplest form of a two neuron reflex arc
Sensory neuron near the spinal cord
Meets a motor neuron
Knee jerk is a 2 neuron r3flex arc
3- Neuron reflex arcs
Sensory neuron
Interneuron in the spinal cord
Motor neuron
An example: withdrawal reflex
What is a nerve
Bundle of peripheral axons
Usually have a myelin sheath
Myelin makes them look white
More than one neuron (a bundle or a bunch)
In the CNS, a bundle of axons is called a tract
Nerve signals/Nerve impulse/Action potential
All mean essentially the same thing
Move very fast…..faster than hormones of the endocrine system
No nerve impulse/no life
How does a nerve impulse/action potential move?
Self propagating wave of electrical disturbance
Travels along the surface of a neuron membrane
If the impulse hits Myelin it jumps forward to the next myelinated section
Myelinated nerves send information quicker than unmyelinated
Mechanisms of a nerve impulse-=resting membrane potential-Polarized
There is a difference in the CHARGES around a nerve
Slightly more positive on the outside(polarized)
When the nerve is stimulated sodium ions move across the neurons membrane
Mechanisms of a nerve impulse-Depolarization
Depolarization= Action potential= Nerve fires
The inside becomes more positive than the outside
Repolarization
Happens immediately
Outside becomes more positive again
Goes back to its resting potential
From one nerve to the next
Synapse: place where impulses are transmitted from one neuron to the next
Neurotransmitters:unlock the doors to the next neuron
Open channels
Are chemicals
Allow neurons to commune with each other
Components of synapse
Examples of neurotransmitters- chemicals that allow neurons to communicate
Acetylcholine (ACh)
Amines (formerly known as catecholamines)
Norepinephrine (as a medication used to increase and maintain blood pressure)
Dopamine (feelings of pleasure)
Serotonin- happy chemical (medicines that increase serotonin can help with depression)
Endorphins- body makes (body’s natural pain killers Released when body feels pain or stress)
Enkephalins (Released in the dorsal horn of the spinal cord and inhibit pain fibers) morphine like
Nitric oxide (NO) - 30% Nitrous oxide delivered by full mask is equivalent to 10 to 15 mg of morphine
Central glia (neuralgia)
Supported cells
Bringing the cells of nervous tissue together
Structurally and functionally
3 main types of glial cells in the CNS
Astrocytes- anchor
They are star shaped cells
Anchor small blood vessels to neurons
Microglia- clean up
Small cells that remove inflamed brain tissue via phogocytosis
Oligodendrocytes
Form myelin sheaths in the CNS—Schwann cell in the PNS
What’s a tract
A bundle of CENTRAL axons
White matter- primarily myelinated axons
Gray matter-primarily cell bodies and unmyelinated fibers
In the peripheral nervous system (PNS) a bundle of axons is called a nerve
Meninges
Brain is protected by skull/ cranium
Spinal cord is protected by vertebrae
Both are protected by 3 layers of meninges
PIA matter-inner most layer
ARACHNOID matter-between pia and dura
DURA matter-outer layer
(Bolded) fluid spaces-between layers
Around the spinal cord
Ventricles in brain
Divisions of the brain
Brain stem
Cerebellum
Diencephalon
Cerebrum
Brain stem 3 parts
Medulla oblong at a
Pons
Midbrain
Conducts impulses to higher parts of brain
From higher parts of brain to spinal cord
Cerebellum
Second largest part of brain
Folded it to make a large surface area
Located under occipital lobe of the cerebrum
Essential for normal movement
Coordinated muscle movements
Balance

The emotional brain
Amygdala
Hippocampus
Diencephalon- between midbrain and cerebrum
Diencephalon
Small but important
3 major divisions
Hypothalamus, thalamus, pineal gland
Hypothalamus (Controls automatic nervous system)
Located below thalamus
Posterior pituitary gland and pituitary stalk
Control center for automatic nervous system (ANS)
Helps to control most of the internal organs
Hormone secretion
Body temperature
Appetite
Wakefulness
Pleasure
Central nervous system regions
Thalamus
Dumbbell shaped is a sensation pleasant or unpleasant?
Arousal
Emotions
Alerting
Regulates level of consciousness
Pineal gland
Size of a pine nut
Behind thalamus
Time keeping hormone (melatonin)
Response to changing levels of outside light
Cerebrum
Largest part of human brain
Upper most part
Cerebral cortex
Regulates automatic movements and posture
Mental processes of all types: Sensations, consciousness, memory, voluntary control of movements
Spinal cord
Outer portion-two way conduction path (afferent & efferent)
Bundles of myelinated nerve fibers (tracts)
Interior portion
Gray matter- Mostly neuron dendrites and cell bodies unmyelinated
Average length -17-18 inches

Responsible for reflexes
Has both
Sensory tracks: Impulses to the brain
Motor tracks: impulses from the brain
Severed spinal cord: Impulses can’t travel to the brain from any part of the body below the injury
