Chapter 9 and 10.ppt

7/28/2019 Chapter 9 and 10.ppt

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Nervous System


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Chapter 9

Spinal Cord & Spinal Nerves


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Nervous system

Chief coordinator for all organ systems

Effectorsmuscles or glands that receive

commands from nervous system


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Nervous System

Structural Divisions

Central Nervous System (CNS)

Brain

Spinal cord

Peripheral Nervous System (PNS)

Cranial nerves

Spinal nerves

All other nerves


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Functional Divisions

Somatic nervous system

Voluntary control

Autonomic nervous system (visceral n.s.)

Sympathetic

Parasympathetic


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Neuron

DendritesAre receptors for nerve impulses

Axoncarries impulses away from the cell body

Myelin sheathprotects axon fiber, produced by

Schwann cells in PNS, between myelin, are nodes ofRanvier


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Neurons

Sensory neurons (afferent)-carry signals

to brain

Motor neurons (efferent)-carry signals

away from brain

Interneurons-relay information within

CNS


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Nerves

Sensory nerves

Motor nerves

Mixed nerves


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Nerve structure

Endoneurium

Around fibers (axons)

Perineurium

Around fascicles

Epineurium

Around entire nerve

Same as muscle but with

neur instead of mys


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Nerve impulse

Nerves send signals via action potentials

An action potential occurs when the

charge shifts between the inside and

outside of the fibers.


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Action Potential

Na+ ions outside the axon and K+ ions inside the

axon

Na+ ions transported inside, creating large

positive charge on inside of the axon, triggeringthe same transporters further down the axon

K+ ions transported out, returning the charge to

resting state

Saltatory conduction: this depolarization occurs

at the nodes along the myelin sheath


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Synapses

Synapse junction between a nerve cell

and another cell

Presynaptic cell

Postsynaptic cell

Synaptic cleft

Neurotransmitter

Receptors


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Synapses

Neurotransmitters Acetylcholine

Adrenaline (epinephrine)

Norepinephrine

Signals cease by: Diffusion away from synapse

Enzymatic breakdown of neurotransmitter(acetylcholinesterase)

Reuptake

Electrical impulses Direct continuation of action potential allowing rapid

and coordinated communication

Cardiac, smooth muscle


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Spinal cord

Connects PNS to brain

Central gray matter

surrounded by whitematter

H formed from ventral

and dorsal horns


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Spinal Cord

Ascending tracts nerve fibers carrying

signals to the brain

Descending tracts nerve fibers carrying

signals away from the brain


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Spinal Cord

Reflex arc

1. Receptor

2. Sensory neuron

3. CNS

4. Motor neuron

5. Effector


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Spinal Cord

Spinal nerves

31 pairs of spinal

nerves

Attached to spinal

cord via dorsal root

and ventral root

Dorsal root ganglion(sensory neuron

bodies)


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Spinal Cord

Spinal nerves

Ventral root motor

(efferent) nerve fibers

Dorsal root sensory

(afferent) nerve fibers


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Spinal Cord

Dermatomes


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Autonomic Nervous System

Sympathetic

Parasympathetic


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Sympathetic

Motor neurons originate in spinal cord in

thoracic and lumbar regions

Preganglionic

Synapse with Postganglionic motor neurons

found in ganglia

Neurotransmitters epinephrine (adrenaline),norepinephrine

Adrenergic


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Parasympathetic

Motor neurons originate in brain stem and

sacral region of spinal cord

Synapse with postganglionic neurons near

walls of effector organs

Terminal Ganglia

Neurotransmitters acetylcholine Cholinergic


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Sympathetic Nervous system involved ininitiating fight or flight response Increase in rate and force of heart contractions

Increase in blood pressure

Dilation of blood vessels to skeletal muscles Dilation of bronchial tubes

Stimulation of adrenal medulla

Dilation of pupil

Decreases action of unneeded systems (urinary,digestive)

Parasymathetic nervous system works inreverse


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Chapter 10

The Brain


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Brain

Cerebrum

Diencephalon

Brain stem Cerebellum


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Brain

Meninges

Dura mater

Arachnoid mater

Pia mater


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Brain

Cerebrospinal Fluid (CSF)

Circulates in & around brain

Carries nutrients, absorbs shock

Ventricles

Choroid plexus forms CSF


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Brain

______

______

______

______

____________

______

______

______


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Cerebrum

Cerebral Hemispheres

Frontal lobe

Parietal lobe

Temporal lobe

Occipital lobe


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Cerebrum

Cerebral Cortex

Gray matter

Conscious thought, reasoning, abstract ideas

Gyri / gyrus -protruding portions Sulci / sulcus -grooves

Central sulcusbewteen frontal & parietal

lobes Lateral sulcusbetween temporal & f & p

lobes


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Cerebrum

Inner portion of brain = mostly white matter

*white matter = myelinated axons

Communication b/w areas of brain

Some areas of gray matter within white

matter

Basal nuclei / basal ganglia

Work with cerebral cortex coordinating body

movement, facial expression


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Cerebrum

Corpus collosum at bottom of

longitudinal fissure, allows communication

b/w hemispheres

Internal capsule myelinated fibers

carrying signals from cerebrum to brain

stem


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Cerebrum

Functions of lobes

Frontal

Precentral gyrus contains the primary motor

area

Parietal

Postcentral gyrus contains the primary

sensory area

Homunculus


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Cerebrum


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Cerebrum


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Cerebrum

Temporal

Olfactory area

Auditory areas

Auditory receiving area Auditory association area

Wernickes area

Occipital

Visual receiving area

Visual association area


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Cerebrum

Frontal (again)

Brocas area


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Diencephalon

Diencephalon contains the

Thalamus

hypothalamus


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Thalamus sorts incoming sensory

impulses, send to particular region of

cerebral cortex

Hypothalamus controls body temperature,

water balance, sleep, appetite, emotions

such as fear and pleasure, pituitary gland


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Brain Stem

Midbrain

Pons

Medulla oblongata


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Brain Stem

Midbrain

Contains four centers of gray matter

responsible for eye and ear reflexes

Contains white matter for conducting impulsesfrom higher centers in cerebrum to lower

centers in pons, medulla, & cerebellum

Cranial nerves III-IV originate here


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Brain Stem

Pons

Largely white matter, connects cerebrum with

brain stem & spinal cord

Respiration reflex regulation occurs here

Cranial nerves V-VIII originate here


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Brain Stem

Medulla oblongata Externally white matter, internally gray matter

Nuclei in gray matter serve as Respiratory center

Controls respiratory muscles

Cardiac center

Regulate rate & force

Vasomotor center

Controls smooth muscle in blood vessels

Nerve tracts decussate here (criss-cross)contralateral control

Cranial nerves IX-XII originate here


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Cerebellum


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Cerebellum

Outer gray matter, inner white matter

(arbor vitae)

Vermis & Two hemispheres


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Cerebellum

Outer gray matter, inner gray matter (arbor

vitae)


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Cerebellum

Coordinates voluntary muscles ensuring

smooth function

Maintains balance standing, walking, &

sitting

Maintains muscle tone to ready for full

muscle contraction


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Brain Disorders

Meningitis

Inflammation of the meninges, caused by

bacterial infection

Encephalitis

Inflammation of the brain, usually caused by

viral infection


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Brain Disorders

Hydrocephalus

Accumulation of CSF in ventricles puts

pressure on the cerebrum, destroying brain

tissue

Stroke / cerebrovascular accident

Blood clot or vessel rupture resulting in brain

tissue damage


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Brain Disorders

Aphasia

Receptive (loss of ability to understand) or

expressive (loss of ability to speak or write)

Cerebral palsy

Brain damage during or before birth resulting

in muscular weakness or paralysis


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Brain Disorders

Epilepsy

Disorder in the brains electrical activity

Seizures characteristic of epilepsy


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Brain Disorders

Alzheimer disease

Degeneration of cerebral cortex and

hippocampus

Memory loss followed by mood changes,confusion


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Brain Disorders

Multi-infarct dementia

Accumulated brain damage (usually from

many small strokes) causing a short blood

supply to the brain, resulting in loss ofmemory, judgment, cognitive function


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Brain Disorders

Parkinson disease

Cell death in brain in the part that produces

the neurotransmitter dopamine.

Results in overactivity of basal nuclei, whichcontrol voluntary movement


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Cranial Nerves

12 pairs of cranial nerves

OOOTTAFVGVAH


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Cranial Nerves

I. OlfactoryII. Optic

III. Oculomotor

IV. Trochlear

V. TrigeminalVI. Abducens

VII. Facial Nerve

VIII. Vestibulocochlear

IX. Glossopharyngeal

X. Vagus

XI. Accessory

XII. Hypoglossal


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Cranial Nerves

Olfactory smell impulses from nose to

brain

Optic visual impulses from eye to brain

Oculomotor controls eye

muscles/movement


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Cranial Nerves

Trochlear controls only one eye muscle

Trigeminal 3 branches of sensory nerves

for the face and head. Also chewing.

Abducens also controls only one eye

muscle


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Cranial Nerves

Facial muscles of facial expression. Also

taste, salivary, and tear glands.

Vestibulocochlear hearing and

equilibrium impulses from ear to brain.

Glossopharyngeal sensory impulses

from tongue and pharynx. Also

swallowing.


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Cranial Nerves

Vagus Supplies organs in the abdominal

and thoracic cavities. Also, larynx &

pharynx.

Accessory Trapezius andsternocleidomastoid. Also, larynx.

Hypoglossal controls tongue muscles


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1. What is the outer most meningeal layer?


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2. The cerebral cortex is composed of:

white matter; or

gray matter


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3. The precentral gyrus contains the:

primary motor area

primary sensory area


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4. What structure in the brain controls body

temperature, water balance, sleep,

appetite, emotions such as fear and

pleasure, and the pituitary gland?


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5. Encephalitis is the inflammation of what?


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6. Excess accumulation of cerebrospinal

fluid in the ventricles causes:

Alzheimers disease

Parkinsons disease

Hydrocephaly


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7. What part of the brain contains white

matter in the shape of a tree, called the

arbor vitae?


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8. How many pairs of cranial nerves are

there?


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9. Name one cranial nerve that serves the

eye.


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10. Name any other cranial nerve.

Chapter 9 and 10.ppt

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