CH. 12 Central Nervous System

cephalization

concentration of nervous tissue in the head

1. cerebral hemispheres

2. diencephalon

3. brain stem

4. cerebellum

what are the adult brain 4 regions?

midbrain, pons, medulla oblongata

what does the brain stem consist of?

gray matter

NON-MYELINATED NEURONS and cell bodies

white matter

MYELINATED and NONMYELINATED AXONS

-fat/lipid with protein

basic pattern found in CNS

central cavity SURROUNDED by GRAY MATTER, WHITE MATTER external to GRAY MATTER

(pattern change ascending brain stem)

cortex

what the cerebral hemispheres (cerebrum) and cerebellum contain OUTER LAYER OF GRAY MATTER

spinal cord pattern

-inner gray matter

-outer white matter

cerebrum and cerebellum pattern

-islands of gray matter (nuclei) within white matter

-cortex of gray matter

ventricles

filled with cerebrospinal fluid

-lined with ependymal cells (neuroglial cells)

-paired lateral ventricles separated by membranous septum pellucidum

diencephalon

where third ventricle lies in

cererbral aqueduct

how third ventricle is connected to fourth ventricle

cerebral hemispheres

form superior part of brain

-account for majority of brain mass

gyri

ridges

sulci

shallow grooves

fissures

deep grooves

longitudinal fissure

seperates two hemispheres

transverse cerebral fissure

seperates cerebrum and cerebellum

insula

lobe buried under portions of temporal, parietal, and frontal lobes

-not visible on surface

central sulcus

Separates precentral gyrus of frontal lobe and postcentral gyrus of parietal lobe

parieto-occipital sulcus

Separates occipital and parietal lobes

lateral sulcus

outlines temporal lobes

each hemisphere’s basic regions

-cerebral cortex of gray matter on surface

-internal white matter

-basal nuclei deep within white matter

cerebral cortex

“executive suite” of the brain

-site of CONSCIOUS MIND: awareness and sensory perception

4 considerations of CEREBRAL CORTEX

1. Motor areas: control voluntary movement

2. Sensory areas: conscious awareness of sensation

3. Association areas: integrate diverse info into all one unique event

4. Lateralization: (specialization) of cortical function occure in only ONE hemisphere

contralateral

opposite (side of body)

primary (somatic) motor cortex

stimulate skeletal muscle

-pyramidal cells: large neurons in charge of allowig control of precise, skilled skeletal muscle movement

premotor cortex

helps plan movements

-ctrl learned, repeated, or patterned motor skills

broca’s area

in charge of communication; physically initiate speech and forming words

-planning speech

frontal eye field

control voluntary eye movements

stroke or muscle paralyzation

damage to PRIMARY MOTOR CORTEX results in…

neural plasticity

ability of brain to change its function by changing its structure

-brain can rewire in certain cases to maintain function

primary somatosensory cortex

recieve sensory info from skin and proprioceptors (relating info relation to body position) of skeletal muscle, joints, tendons

primary somatosensory cortex

capable of SPATIAL DISCRIMINATION: identification of body region being stimulated (what is the cortex?)

somatosensory association cortex

organize sensory neurons and understand object of sensation

somatosensory association cortex

determines size, texture, and relationship of parts of objects being felt is the function of what cortex?

primary visual (striate) cortex

bipolar retina neuron = perceve changes in light

-recieve info from retinas

visual association area

-surrounds primary visual cortex

-uses past visual exp. to interpret visual stimuli

ex. ability to recognize faces

primary auditory cortex

interpret info from inner ear as pitch, loudness, location

-what u hear

auditory association area

store memories of sounds and allows perception of sound stimulus

-what the sound means

vestibular cortex

responsible for conscious awareness of balance (position of head in space)

-Consciously aware of position

primary olfactory cortex

-conscious awareness of odors

-primative rhinencephalon, smell baby, food..

gustatory cortex

perception of taste

*taste and smell go together

visceral sensory area

Perceive fullness or stretch of organs

anterior of brain

where can you find motor areas of the brain?

posterior of brain

where can you find sensory areas of the brain?

damage to primary visual cortex

functional blindness; patient can see but do not comprehend what they are looking at

multimodal association areas

recieve inputs from multiple sensory areas and send outputs to multiple areas ex. we hear before we see

-gives meaning. connection to sensation, thoughts, emotions; makes us who we are

stages sensory receptors take through the brain

sensory receptors > primary sensory cortex > sensory association cortex > multimodal association cortex

prefrontal cortex / anterior association area

-unique personality

-form working memory

-reason + judgement

posterior association area

recognizing patterns and faces and localizing us in space

-”do i know what im looking at and where it is in relation to me?”

limbic association area

provides emotional impact that helps establish memories

cerebral dominance

hemisphere that is dominant for language (most humans have left sides dominance in brain, meaning they use right side of their body more)

lateralization

division of labor between hemispheres

-hemispheres are not identical

left hemisphere

control language, math, logic

(what is the hemisphere?)

right hemisphere

visual-spatial skills, intuition, emotion, artistic and musical skills

(what is the hemisphere?)

association fibers

horizontal running fibers that connect different parts of the same hemisphere

(white matter)

commissural fibers

horizontal fibers that connect gray matter of two hemispheres

projection fibers

vertical fibers that connect upper hemispheres with lower brain or spinal cord

basal nuclei

minimize unnecessary behaviors

-influence muscle movements, play role in cognition and emotion

Parkinson’s and Huntington’s disease

disorders of basal nuclei

-eg.. tremors

thalamus, hypothalamus, epithalamus

what are the 3 paired gray matter structures in the Diencephalon

thalamus

relay station for information coming in the cortex (afferent + efferent)

-sorts, edits, relays ascending input

-EVERYTHING goes through EXCEPT olfactory (smell) >goes to olfactory cortex

hypothalamus

-influences how endocrine system work

-maintains homeostasis of automatic nervous system (blood pressure, response to emotion), AND part of limbic system(pleasure, fear)

-regulate body temp, hunger/satiety, water balance/thirst, sleep-wake cycle

epithalamus

-contains pineal gland (secretes melatonin to regulate sleep-wake cycle; fall sleep)

automatic behaviors necessary for survival

what does the brain stem control?

superior colliculi

-connect to corpora quadrigemina

visual reflex centers

-Reflexive action to what you see

inferior colliculi

-connect to corpora quadrigemina

auditory relay centers

-Reflective action to what you hear

substantia nigra

functionally linked to BASAL NUCLEI (ctrl uncontrolled contraction)

-black appearance in midbrain

-Parkinson’s disease is degeneration of this area

pons

maintains normal rhythm of breathing

medulla oblongata

medulla = automatic reflex center

• cardiac center : adjust force and rate of heart contraction

• vasomotor center : adjust blood vessel diameter = blood pressure regulator

• respiratory center : ctrl rate and depth of breathing

• other centers: vomiting, hiccupping, swallowing, coughing, sneezing

cerebellum

Provide precise coordinated movements of skeletal muscles

-plays MAJOR role in BALANCE

-process input from cortex, brain stem, and sensory receptors

limbic system

puts feeling to different stimuli - memory of an event

-EMOTIONAL RESPONSE TO ODORS

-hippocampus : tied to memory formation

Wernike’s area

involved in understanding spoken and written words > using correct words together

declarative memory

names, faces, words, dates

procedural memory

playing piano

motor memory

memory of motor skills (riding bike)

emotional memories

memory of experiences linked to an emotion (heart pounding when you hear a rattlesnake)

short term memory

temporary holding of info

long term memory

has limitless capacity for memory

automatic memory

subconscious information stored in long term memory (what ur brain is doing when ur asleep : sorting and filing)

memory consolidation

involve fitting new facts into categories already stored in cerebral cortex

fainting / syncope

brief loss of consciousness due to inadequate blood flow to brain

coma

Unconsciousness for extended period

brain death

irreversible coma (put on life support)

epileptic seizure

torrent of electrical discharges by groups of brain neurons

-incorrect pace of firing rate > throwing everybody else off accululation

absence seizure (petit mal)

mild seizure which expression goes blank for a few seconds

-seen in children

tonic-clonic seizure (grand mal)

most severe seizure; last lew mins

-victim lose consciousness

aura

sensory hallucination that may precede seizure

meninges

protective covering of brain

dura mater

“tough mother”

-strongest meninx

• periosteal layer: attach inner surface of skull

• meningeal layer: true external covering of brain

acrachnoid mater

middle layer with spinderweb-like extensions

-Separated from dura mater by subdural space

subarachnoid space

space in arachnoid mater that contains cerebral spinal fluid and largest vessels of the brain

pia mater

most delicate connective tissue that clings tightly to the brain; physically integrated in brain/spinal cord

meningitis

Inflammation of meninges, which can be deadly

-can swell on brain

cerebrospinal fluid

liquid cushion of constant volume around brain

-hep lighten weight of brain

-brain float

-SHOCK ABSORBER

concussion

temporary alteration in function to brain

“what day is it?” “idk”

contusion

Permanent brain damage

subdural / subarachnoid hemorrhage

pressure from blood may force brain stem through foramen magnum (death!)

cerebrovascular accidents

strokes - brain deprieved of oxygen