ap chapter 13 CNS

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99 terms · ap chapter 13 CNS

CNS (3)

Brain (with many folds make it bigger) & spinal cord
spinal cord starts at crista galla and ends at pia matter

secures to side to ___________

Meninges - general + function

in entire CNS
connective tissue
functions:
1. secures brain & SC
2. provides space for fluid
3. protective coating

Meninges consists of (4)

1. Dura mater - tough fibrous connective tissue, outer layer. 2 layers in brain. 3 inward extensions
a. Falx cerebri - blood vessels inside. partition btw the 2 cerebral hemispheres. projects downward from longitudinal fissure)
b. Falx cerebelli - blood vessels inside. separates the 2 halves/hemispheres of cerbellum
c. Tentorium cerebelli - separates cerebellum from cerbrum. (tentilike covering over cerebellum)
2. Arachnoid mater ("spider") cobweb like matter btw dura mater & pia mater
3. Pia mater - transparent covering following grooves & crevices. adheres to outer surface of brain & SC, contains blood vessels
a. Filum terminale
4. Spaces
a. Epidural - only in SC. immediately outside dura mater but inside bony coverings. btw bone & dura mater.
b. Subdural - btw dura mater & arachnoid mater. potential space only when bleeding, etc.
c. Subarachnoid -under arachnoid & outside pia mater. brain & SC. contains spinal fluid.

Meninges - Dura mater

1. Dura mater ("hard mother") tough fibrous connective tissue. outer layer. Two layers in the brain. covers nerve roots
-Blood vessels in brain. 3 inward extensions:
a. Falx cerebri - in crevices. blood vessels inside. partition btw the 2 cerebral hemispheres
b. Falx cerebelli - in crevices, blood vessels inside. separates the 2 halves/hemispheres of cerbellum
c. Tentorium cerebelli - separates cerebellum from cerbrum

-sinus is a blood vessel
dura sinus in dura mater - if you tear dura mater bleeding can happen

Meninges - Arachnoid mater

"spider"
cobweb like matter btw dura mater & pia mater

meninges - Pia mater

1. transparent covering following grooves & crevices.
2. on top of nervous tissue.
3. adheres to outer surface of brain & SC, contains blood vessels
a. filum terminale

meninges spaces epidural

only in SC. immediately outside dura mater but inside bony coverings. btw bone & dura mater.

meninges spaces subdural

btw dura mater& arachnoid mater. potential space only when bleeding, etc.
bleeding will cause death due to pressure, cuts off blood supply & brain needs oxygen

meninges spaces subarachnoid

under arachnoid & outside pia mater. brain & SC. contains spinal fluid.

sinus

is a blood vessel

filum terminale

the pia mater forms this slender filament & ties to the bottom of SC. starts at crista galla

cerebrospinal fluid (CSF) functions & general (2)

1. Protective cushion (a lot of water)
2. Monitored to detect changes (chemical) in the internal environment. HOMEOSTASIS

-found in the subarachnoid space, within cavities & canals of the brain & SC

CSF - ventricles (3) & general

In brain tissue, fluid (spinal) filled spaces. ependymal (glia) cells found here.
1. First and second ventricles (lateral) = located one in each hemisphere.
2. Third ventricle = middle of brain. thin, below & medial to the lateral ventricles
3. Fourth ventricle = in the brainstem. diamond shaped where the cerebellum attaches to back of brainstem

Note: spinal fluid made here & flow out to subarachnoid.

CFS Lateral ventricle (2)

First and second ventricles (lateral) =
1. located one in each hemisphere. within cerebral hemispheres
2. separated by septa pellucida

CFS Third ventricle (3)

1. Within diencephalon
2. middle of the brain
3. below & medial to the lateral ventricles

CFS Interventricular foramina

Join lateral ventricles with third ventricle

CFS - Fourth ventricle (5)

1. Associated with pons and medulla oblongata. in the brainstem.
2. Connected to third ventricle by the cerebral aqueduct
3. Continuous with the spinal cord
4. Connected to the subarachnoid space
5. diamond shaped where the cerebellum attaches to back of brainstem
Note: goes in central canal

Formation & circulation of CSF

1. Choroid plexus - produces CFS, which is the separation of fluid from blood
2. Arachnoid villi
a. Arachnoid granulations

Steps of circulation of CSF

1. choroid plexus release CSF into fluid spaces
2. fluid from lateral ventricles seeps throu interventricular formen into 3rd ventricle
3. then thru cerebral aqueduct (of Sylvius) into 4th ventricle
4. some fluid goes into central canal of SC & some into subarachnoid spaces & absorbed into venous blood thru arachnoid villi (fingerlike projections)
5. absorbed back into blood

Note: make it, circulate it & reabsorb it

brainstem - 3 parts

1. medulla oblongata
2. pons
3. midbrain

alive because of this. enables you to breathe & cardiac movement
brain death = loss of brain stem. test = interior, superior & medulla oblongata

brain stem - functions (3)

Performs sensory, motor, and reflex functions

brainstem - medulla oblongata

1. a lot of nerve fibers
2. Pyramids - rounded, motor tracks either thru or around
3. Nuclei - cell body in CNS, vital functions. ex. breathing
4. Control centers - e.g. respiratory control center; cardiac control center (change of rate or pressure). ex. cough, sneeze, reflexes)

brainstem - pons

pathways to cerebellum

Note: in lab look for 4th ventricle, its behind pons

brainstem - midbrain (mesencephalon)

1. Corpora quadrigemina (four bumps)
a. Inferior colliculus- contains auditory centers (bottom bumps) Inferior = auditory reflex (ex. turn in direction of sound)
b. Superior colliculus-contains visual centers (top bumps) involved in reflexes. Superior = visual reflex (ex. eyes move in direction of head)

cerebellum - general

back of brainstem
1. arbor vitae ("tree life")
2. Hemispheres and the vermis (separates into hemispheres)

cerebellum - functions (3)

1. Produce skilled movements (fingers, ability to coordinate)
2. Controls skeletal muscles to maintain balance/posture. problem w/cerebellum (like drunk walking) ataxia=poor gait, problem w/cerebellum, also
3. Controls posture. problem w/ posture, then problems w/cerebellum

diencephalon

"two-brain". above midbrain. connection btw cerebrum & the rest of the body.
1. Thalamus, hypothalamus, optic chiasma & pineal body

Thalamus - Characteristics & function (5 of 10)

1. Relay all kinds of sensory impulses (except smell) & process. major relay station for sensory impulses
2. makes up wall of 3rd ventricle/Surrounded by third ventricle
3. Two lateral portions connected by the intermediate mass (looks like an eye)
4. Sensory information from spinal cord synapses
5. Plays part in emotions

Thalamus - Characteristics & function (5 of 10)

6. Plays part in arousal mechanism (to keep you awake) reticular activiting system - how you wake up in the morning
7. nervous tissue.
8. can block out pain, filtered
9. one is a space = 3rd ventricle
10. one is tissue = thalamus

thalamus (sense)

1. sensory (everything - feel of clothes, sitting on chair)
2. determines if you are going to be aware of sense & where it should go.
3. you won't sense everything

diencephalon - hypothalamus - general (4)

1. Floor of 3rd ventricles (can't live w/o)
2. Mamillary bodies - 2 areas of white matter - sense of smell
3. Infundibulum - hollow stalk (attaches to pituitary gland)
4. Links nervous system to endocrine system

Hypothalamus - Functions (6)

1. Regulator and coordinator of autonomic activities (nervous system, involved in HOMEOSTASIS
2. Relay station between the cerebral cortex and lower autonomic centers
3. Synthesizes hormones secreted by posterior pituitary (controls water balance, conserves water, controls pituitary)
4. Role in arousal mechanism (stimulates to wake you)
5. Appetite (you like it) & satiety (tells you that you are full) center
6. Maintains normal body temperature. resets your body temp. (ex. fever then shiver, if you have stroke & can't control hypothalamus then you die b/c you can't control body temp)

medulla functions (2)

1. relays sensory info to thalamus & to other portions of brainstem
2. autonomic centers for regulation of visceral functions (ex. cardiovascular, respiratory & digestive)

choroid plexus (4)

1. formation of CSF
2. separation of fluid from blood
3.covered in ependymal (glia cells) that release CSF into fluid spaces
4. projects from pia mater into lateral ventricles

pons - functions (2)

1. relays sensory info to cerebellum & thalamus
2. subconscious somatic & viseral motor centers

corpa quadrigemina

4 bumps in midbrain

inferior colliculus

bottom bumps in corpa quadrigemina (midbrain)
1. contains auditory centers
2. auditory reflexes ( ex. turn head in direction of sound)

superior colliculus

top bumps in corpa quadrigemina (midbrain)
1. contains visual centers
2. visual reflexes (ex. eyes move in direction of head)

midbrain/mesencephalon - functions (3)

1. processing of visual and auditory data
2. generation of reflexive somatic motor responses
3. maintenance of consciousness

sulci/sulcus

grooves, shallower than fissures

gryi/gyrus

raised areas ("sausage")

reticular activating system

thalamus.
how you wake in the morning

pineal body (epithalamus)

"pie neil"
1. Involved in regulating the body's biological clock
2. Produces melatonin - stimulates & prevents you from releasing it.
-also in endocrine system
-in line w/eye. stimulated by sunlight. sunlight hits you and you are awake

optic chiasma

1. right & left optic nerves cross before entering brain
Bottom view = look for "X"
saggital view = look for oval
optic tract = coming out of optic chiasma
optic nerve = going into optic chiasma

fissure

deeper groove, deeper than sulcus

Cerebrun 5 lobes

frontal, parietal, temporal, occipital & insula

longitudinal fissure

deepest groove down the center

central sulcus

groove btw frontal lobe & parietal lobe

lateral fissure

deep groove btw the temporal lobe below & the frontal and parietal lobe above

transverse fissure

btw cerebellum & occipital lobe

frontal lobe (3)

Precentral gyrus is part of this (motor)
1. Voluntary control of skeletal muscle
2. Motivation, aggression, mood, personality (a lot due to chemical, some behavorial)
3. Planning, social judgment, intelligence

parietal lobe (3)

Postcentral gyrus is part of this (sensory)
1. Major center for reception and evaluation of most SENSORY information
2. EXCLUDING smell, hearing and vision
3. Including taste, touch, pressure, temperature, and pain

occipital lobe (1)

1. Vision
2. Entire lobe involved

temporal lobe (2)

1. Smell and hearing
2. Memory, visual recognition (part based on memory), emotional behavior

insula lobe (3)

1. pull apart lateral fissure
2. Part of limbic system (emotion)
3. Plays a role in understanding spoken language, taste, and in integrating sensory information from visceral receptors
4. sensation, emotion, understanding of spoken word

cerebrum - hemispheres

1. right cerebral hemisphere = sensation & movement on left side of body
2. left cerebral hemisphere = sensation & movement on right side of body

Basal nuclei

1. Masses of gray matter deep within cerebral hemispheres (beneath the cerebral cortex
2. cell bodies in CNS
3. Produce dopamine
4. Control certain muscular activities
a. Inhibits motor functions (if can't produce dopamine then excessive motor functions = than Parkinsons)

Cerebral tracts - general & 3 types of tracts

A. nerve fibers = tracts
B. in the internal white matter of cerebrum
3 Types
1. Projection tracts
2. Association tracts
3. Commissural tracts

Projection tracts (3)

1. tracts w/in white matter of cerebrum
2. extension of the ascending/sensory tracts (spinothalamic tracts) & descending/motor tracts
3. outside brain to inside & inside brain to outside

Association tracts (3)

1. tracts w/in white matter of cerebrum
2. most numerous
3. same side of brain, from gyri to gyri

Commissural tracts (3)

1. tracts w/in white matter of cerebrum
2. compose the corpus callosum
3. extend from a point in one hemisphere to a point in the other hemisphere ("right hand knows what the left hand is doing")

Cerebrum functions

1. Postcentral gyrus-somatic sensory area
2. Precentral gyrus-somatic motor area
3. Transverse gyrus-primary auditory area
4. Occipital lobe-primary visual areas
5. Integrative functions of the cortex
a. Consciousness
b. Language
i. Aphasia
c. Emotions
i. Limbic system
d. Memory
i. Engrams

Postcentral gyrus

somatic sensory area, receives impulses from receptors activated by heat, cold, & touch stimuli

Precentral gyrus

somatic motor area, impulses from neurons in this area descend over motor tracks & eventually stimulate somatic effectors, the skeletal muscles

transverse gyrus

primary auditory area

Integrative function of cerebrum
Consciousness

who, when & where you are
1. Confusion = usually can tell who you are
2. Delirium = confused then alert
3. Obtundation = a lot of stimulus to bring them alert
4. Stupor = respond to pain but not to you
5. Coma = don't respond to anything

Reticular formation (RAS)

1. Complex network of nerve fibers scattered throughout the brain stem (comes into thalamus, then thru out brain to get everything running)
2. Extends into the diencephalon
3. Connects to centers of hypothalamus, basal nuclei, cerebellum, and cerebrum
4. Filters incoming sensory information
5. Arouses cerebral cortex into state of wakefulness
6. you can filter out sounds thru training

Reticular formation (RAS)

both direct spinal reticular tracts & collateral fibers from sensory tracts relay impulses over the RAS to the cortex. W/O continual excitation of cortical neurons by reticular activating impulses then unconscious

Integrative functions of the cortex
Language

1. Aphasia
2. Two major categories of aphasia: expressive (motor) and receptive (sensory).
3. Expressive aphasics can understand language, but can't express it.
4. Receptive aphasics don't understand speech but have no trouble speaking.
5. Can cause problems with spoken language and written language

Integrative functions of the cortex
Language - Aphasia

problem with language

Integrative functions of the cortex
Language - Aphasia 2 types

1. Expressive aphasics can understand language, but can't express it. can't talk about what you asked
2. Receptive aphasics don't understand speech but have no trouble speaking. can't make sense of what someone is saying

Integrative functions of the cortex
Memory - Engrams

Engrams = how we store a memory/pattern of memory

Integrative functions of the cortex
Memory - Acquistion

1. Acquisition - learn the information
a. Short-term memory

Integrative functions of the cortex
Memory - Consolidation

1. Consolidation - nerve pathways have to be strengthened and reinforced. This is a chemical change in neurons. Needs time to move to long term memory
a. Long-term memory

Integrative functions of the cortex
Memory - Retrieval

1. Retrieval - brain reactivates a particular pathway, and information is remembered
2. Constantly retrieving it
3. Emotional things help you remember

Limbic system consists of

1. Portions of frontal lobe
2. Portions of temporal lobe
3. Hypothalamus
4. Thalamus
5. Hippocampus - memories
6. Amygdala - fear
7. Pituitary
8. Olfactory bulbs

Limbic system functions

1. Controls emotions
2. Produces feelings
3. Interprets sensory impulses
4. Facilitates memory storage and retrieval
5. Motivational system

Left hemisphere

1. motor control of right side
2. verbal
3. linguistic
4. details
5. practical
6. concrete
7. orderly sequence

right hemisphere

1. motor control of left side
2. visual
3. spatial
4. big picture
5. emotional
6. abstract
7. shapes & patterns

spinal cord

1. Extends from the foramen magnum to the lower border of the first lumbar vertebra
2. Nerve roots - bundle of nerve fibers that project from each side of cord
a. Dorsal nerve root (SENSORY)
b. Ventral nerve root (MOTOR)
3. Spinal nerve = dorsal & ventral come together Pathway from brain to rest of body. can be integration center (2 reflex arc)
4. White matter
5. enlargement in cervical & lumbar regions

Dorsal nerve root

1. bundle of nerve fibers that project from each side of cord
2. (SENSORY)
3. cell bodies of these unipolar sensory neurons make up a small region of gray matter in dorsal nerve root called the dorsal (posterior) root ganglion.

dorsal (posterior) root ganglion

cell bodies of these unipolar sensory neurons make up a small region of gray matter in dorsal nerve root called the dorsal (posterior) root ganglion.

Ventral nerve root

1. bundle of nerve fibers that project from each side of cord
2. Ventral nerve root (MOTOR) - damage & you lose sensation or can feel & not move & you would lose reflex too
3. cell bodies of these multipolar motor neurons are in the gray matter that composes the inner core of the spinal cord

white matter - spinal cord

1. gray & white is opposite than in the brain
2. columns
3. 3 bundles
4. NERVE TRACTS/SPINAL TRACTS

gray matter - spinal cord

1. gray & white is opposite than in the brain
2. horns
3. 3 bundles
4. are cell bodies

spinal cord functions

1. Provides conduction routes to and from the brain
2. Integrator or reflex center for all spinal reflexes

spinal tracts

1. Ascending tracts conduct SENSORY impulses to the brain (going up)
2. Descending tracts conduct MOTOR impulses from the brain to motor neurons reaching muscles and glands (going down)

spinal tract names

know is it motor or sensory, also right & left side of body (opposite)
Ex. spinothalamic = sensory. starts at spinal cord and ends in thalamus

Somatic sensory pathways

1. Primary sensory neurons - impulse until crossover
2. Secondary sensory neurons - crosses over & takes to thalamus
3. Tertiary sensory neurons - thalamus (if it decides to take to cerebrum) to cerebrum
4. Decussate = to crossover (75%)
ex. from finger to brain takes 3 neurons

somatic sensory pathways -
primary sensory neurons

1. impulse until cross over
2. conducts from periphery to CNS

somatic sensory pathways -
secondary sensory neurons

crosses over & takes to thalamus

somatic sensory pathways -
tertiary sensory neurons

thalamus (if it decides to take to cerebrum) to cerebrum
thalamus because it is the sensory unit

somatic sensory pathways -
medial lemniscal system vs.
spinothalamic system

medial lemniscal system - finer touch & sensations
spinothalamic system - cruder touch & sensation

somatic motor pathways

Central nervous system to skeletal muscles

somatic motor pathways - Pyramidal tracts

1. directly innervate motor neurons of spinal cord or brainstem (medulla) involved in movement

somatic motor pathways - Extrapyramidal tracts

1. modulation and regulation of anterior horn (goes around pyramids)
2. Reflex, locomotion, complex movements, posture
**All you need to know is that it is more complicated than pyramidal tract

somatic motor pathways - upper motor neuron

1. bring to lower lower
2. cell body lies in a CNS processing center
3. synapses on the lower motor neuron
4. activity in upper motor neuron may facilitate or inhibit lower motor neuron

somatic motor pathways - lower motor neuron

1. reflex arc - going into SC
2. cell body lies in a nucleus of the brain stem or spinal cord
3. triggers a contraction in innervated muscle:
4. destruction of or damage to lower motor neuron eliminates voluntary and reflex control over innervated motor unit

Electroencephalogram EEG

1. neurons are electrical so you can pick it up
2. Beta waves - busy waves (working on something)
3. Alpha waves-relaxed waves
4. Theta waves - drowsy waves (also when agitated)
5. Delta waves - deep sleep waves

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