chapter 12 anatomy

what is the CNS composed of

brain and spinal cord

what’s the function of the CNS

integration and sending out motor response

what are the four regions of the brain

cerebrum (cerebellar hemispheres)

diencephalon

brain stem

cerebellum

CCBD

what is gray matter composed of

any region of the CNS where you find dendrites, cell bodies, and axon terminals

what is the function of the gray matter

all synapses are found in gray matter

synapses are spaces between two neurons where they RELAY information to one another

SYNAPSES ARE IN THE GRAY MATTER

WHAT IS White matter composed of

myelinated axons

when things are myelinated transmission of signals is faster

function of white matter

passes messages between different areas of gray matter

difference between gray (cerebral cortex) and white in the brain

In the brain: Different arrangmeents of gray/white matter in the CNS. For most of the brain, the gray matter is going to be more peripheral (outer part) The white matter is going to be more central in location. For the gray matter we do give it a particular name the cerebral cortex.

in the brain where is the white matter and gray matter

gray matter is peripheral (outside) white matter is central

brain stem

is one of the lower brain regions that sits closer to the spinal cord. Here the white matter sits more peripherally (outside)

scattered gray matter found within white matter

spinal cord (think of shape of the vertebrae what animal does it look like)

gray matter is in a butterfly pattern surrounded by white matter

so white=peripheral

CENTRAL CANAL l is found at the center of gray matter

what are ventricles

they are in the CNS

chambers filled with cerebrospinal fluid

how many ventricles are there

2 lateral ventricles (one in each cerebral hemisphere)

the third ventricles is found in the diencephalon

the fourth is found in the hindbrain. found in the lower part of the brain right before it connects to the spinal cord

how does the fourth ventricle connect to the third one

connects via CEREBRAL AQUEDUCT

continuous with the central canal of spinal cord

Cerebral hemispheres

are the largest part of the brain

the most superior part of the brain

make up most of the brain mass

three regions of the cerebral hemispheres***

cerebral cortex (gray matter)

white matter

basal nuclei

hemispheres wrinkly appearance

gyri: the ridges that stick out (what we see)

sulci: these are the little grooves

both of these help to increase the surface area of the cerebral cortex

longitudal fissure

Separates the brain into left and right hemispheres.

transverse cerebral fissure

-going to separate the cerebral hemispheres from the cerebellum

-divides the higher brain centers from the lower brain centers

functions of the cerebral cortex (gray matter)

self- awareness, sensation, communication, memory, understanding/learning, initiation of voluntary movement

what are the three main areas of the cerebral cortex***

motor areas

sensory areas

asssociation areas

motor areas

control VOLUNTARY movement

concerned only with skeletal muscle tissue

sensory areas

conscious awareness of sensations

association areas***

intergrate diverse information

that is being received by the brain right now and it is going to link it to past information that you have already experienced. Parts of the brain that help you build memory for things you have already experienced before

what does it mean when it says hemispheres are contralateral

-Fibers that originate on the left side are going to travel down and will cross over to the right side

-if fibers cross over, one side of the brain control the opposite part of the body

-left side of brain control the right side of body***

Primary MOTOR cortex

allows for conscious control of skilled/precise voluntary movements

what are pyramidal cells

large NEURONS found in the PRIMARY MOTOR CORTEX

pyramids are huge

also tend to be myelinated

send info very quickly

synapse with and stimulate motor neurons

what are corticospinal tracts

the primary nerve pathway that carries VOLTUNARY movement signals from the BRAIN down to the spinal cord

HOW AXONS TRAVEL

think like train tracts

motor homunculus

Each region of the brain has an assigned body part

-the larger the body part, the more neurons/communication=better movements

premotor cortex function

PLAN the movement

BEFORE YOU DO SOMETHING YOU NEED TO MAKE A PLAN

Makes a plan, so you can move all of your parts together in sequence. Bc of this there is a lot of communication between the premotor cortex and the primary cortex.

controls voluntary actions that depend on sensory feedback. that is when you move in space depedent on obejcts. sensory feedback helpts to guide our actions

ex trying to walk to a sound

MUST COMMUNICATE WITH THE PRIMARY MOTOR CORTEX

Frontal eye field function

controls voluntary movement of the eye

what is appraxia

they know what body part they have to move but if the premotor cortex is damaged it can’t put tg a plan and the primary cortex will do ABSOLUTLEY nothing

Brocas area

found only on the left side of the brain

necessary for speak production

stimulates muscles in and around the mouth

becomes active as we prepare to speak

what are the general functions of sensory areas of the cerebral cortex

allows for conscious awareness of sensation

primary somatosensory cortex function

The sensory region of the cortex that is responsible for the GENERAL SENSES

Receptors for general are head to toe. Found basically everywhere

delusional ownership

lose sensation in one part of the body due to damage on the homunculus.  The body will response by saying I can’t feel it so it’s NOT MINE. As a result ppl won’t wash that body part or even acknowledge it. They will sometimes think their body part belongs to someone else.

somatosensory association cortex function

relay past experiences with what we are currently experiencing

Going to receive sensory information about touch it will take that information and send it to the somatosensory association cortex. It will link it to sensation we have already have from past experiences

this will allow us to identify objects we have already touched. It helps us decipher specific objects even if we aren’t looking at them. For example, reaching into your bag to grab your keys. You know what they feel like. It helps us tell texture as well

primary visual cortex function

LARGEST cortex of any other

receives visual information that originates on the retina in the eye

visual association area

uses past visual experiences to interpret visual stimuli

helps you to recognize things you have seen before

Primary auditory cortex function

receive info from the cochlea

interprets sound as pitch, loudness, and location

pitch

loudness

location

auditory association area

Looks at sound we are hearing right now and compares with sounds we have heard before. It allows us to remember what certain sounds before. For example, knowing a person just by hearing their voice but not looking at them. Also knowing lyrics to songs

Primary olfactory cortex function

concerned with smell

conscious awareness of different odors

old ppl have a smell

vestiBular cortex function

allows for conscious function of balance/orientation

gustatory cortex funciton

perception of taste

think about your gut

visceral sensory area function

allows conscious perception of visceral organs

ex if a person eats a large amount of food and they stretch out their stomach that’s their cue to stop

larteralization as far as functioning go with the hemispheres

one of the hemispheres may be better at completing certain task as composed to another

there is a division of labor

what is cerebral dominance

one hemisphere dominates a particular task

ex. language

•Left side of brain: language abilities, math, logic

•Right side of brain: visual-spatial skills, insightful, creative

what connects left vs right side of the brain

fiber tracts

allows the brain to recieve information almost instanneously

where is the cerebral white matter

lies deep to the gray matter

so gray matter is on the outside while white is on the inside

function of the cerebral white matter

communication in the CNS

association fibers (cerebral white matter)

myelinated nerve axons that connect different areas of the SAME hemisphere

commissural fibers

connect corresponding areas of different hemispheres

•Benefit: Allows hemispheres to function as a coordinated “team”

projection fibers

extend from cortex down into the spinal cord

allows sensory information to reach cortex and motor output to leave cortex

function of basal nuclei

•Filters out incorrect or inappropriate responses relating to:

•1) Muscle movement

•

•2) Emotions and cognition

ex. torrettes

think like nukes are bad

location of basal nuclei

•deep to the white matter in each cerebral hemisphere

thalamus functions (diencephalon)

sandwhiched between the two hemispheres

It’s identifying the type of sensory information that’s coming in the cerebral cortex and making sure that its’ delivered to the CORRECT part of the cortex.

•Information is “edited” hereàimpulses with similar functions are grouped together and relayed to appropriate part of cortex

hypothalamus function

main visceral control center in the body

When the hypothalamus is called the main visceral control center, it means it acts as the central command station for your viscera—the internal organs inside your chest and abdomen, such as your heart, lungs, stomach, intestines, and bladder.

A) Controls autonomic nervous system

B) Initiates physical response to emotion: limbic system involvement

•Involved in perception of fear, rage, libido, etc.

•

C) Regulates body temperature: the “body thermostat”

D) Regulates food intake

•Monitors blood nutrient levels

E) Regulates water balance and thirst

•Monitors concentration of body fluids

•

F) Regulates sleep-wake cycles

•Uses daylight-darkness cues from visual pathways

•

G) Controls endocrine system function

•Controls secretion of hormones by other glands

Epithalamus

so much pain if makes you wanna pass out

has a pineal gland

the pineal gland secretes the hormone melatonin

When light intensity is low the epithalamus will be stimulated to produce more melatonin. Melatonin makes ppl feel sleepy

functions of the brain stem

Responsible for coordinated rigidly programmed automatic behaviors

Provides pathway for fiber tracts running from higher brain centers to lower brain centers & spinal cord

innervation of the head. provides nerve fibers. 10-12 of the cranial nerves are associated with the brain stem

Functions of the midbrain

1) Regulates motor movement

•

2) Regulates hearing and vision

•

3) Alertness

•

4) Temperature control

The pons

"The pons keeps things passing."

Things passing:

• Air passing in and out (breathing)

• Urine passing out (bladder control)

• Food passing down (swallowing

• Functions:

1) Respiratory control

•

2) Bladder control

•

3) Swallowing

•

4) Most functions associated with attached cranial nerves

the medulla oblongata functions

medulla means marrow

1) Cardiovascular center: regulates heart rate and blood pressure

•

2) Respiratory center: controls respiratory rhythm, depth of breath

cerebellum functions

Receptors in body relay information to cerebellum about body position & where the body is in space

decides best way to execute movement

allows smooth coordinated movement required for everyday life

functional brain stem systems def

•networks of neurons that span multiple regions of the brain and work together to accomplish one or more related tasks

Parts of the brain communicate with one another and this allows for more complex tasks

what is the limbic system

Feel = Limbic system (emotions and memory)

the emotional brain

helps regulate emotions

Amygdala (limbic system) function A=anger

•response to perceived threats with fear or aggression

receive information about some current event it will interpret that incoming information and cause us to respond to that event with either fear or aggression. This is not an all the time thing. This tends to be most active during a flight or fight response.

cingulate gyrus (limbic system) function

•expressing emotions through gestures, resolving mental conflicts during times of frustration

•expressing emotions through physical gestures rather than spoken language. This is also true for facial expressions

Psychosomatic illness

•illness with physical symptoms that results specifically from emotional causes

•Ex: being excited or nervous causes an increase in heart rate, blood pressure

"Stress in the mind becomes symptoms in the body."

Examples:

• You're extremely nervous before an exam → your stomach hurts.

• You're stressed for weeks → you get headaches.

• Anxiety → increased heart rate.

what is the limbic system output relayed through

relayed through the hypothalamus which makes sense bc the hypothalamus is related to the visceral organs

Limbic system interacts with prefrontal cortex

Prefrontal cortex:

-Who you are as a person. It is your entire personality.

- (1)ability to react emotionally to things we are consciously aware of. Ex. You see something you don’t like

-(2) We can pinpoint our emotions

In some cases, you can have logic overriding emotion and vice versa. One has to win over the other. It just depends on the person

Ex. Someone getting back with an ex over and over again

Reticular activating system functions (RAS)

1.Sends a continuous stream of action potential to the cerebral cortex:

-this gives it something to do constantly (keeping it alert)

Filters out repetitive, familiar, or weak signals:

-taking some information being sent to the cortex and just gets rid of it

-prevention of sensory overload.

for example, you wear clothes everyday but you don’t necessarily think or feel them until you think about them. Its not that important, it is very familiar to the RAS gets rid of it temporarily

Some people tend to focus only on the difficult parts of their life. That will rewire the RAS so they will focus entirely on the minor inconveniences and they will become extremely pessimistic

Wernickes area of the brain

language comprehension, “speaking clearly”

-it helps make sure our words aren’t slurring together

-not the physical act of speaking

-as someone is speaking to you, you can understand the words coming out of their mouth

Right hemisphere:

-helps understand what people’s tones are

understand nonverbal components of langauge

short-term memory

stores small amounts of information for short periods of time

long-term memory

stores large amounts of information for longer periods of time

can we forget stuff that gets stored in our long term memory

yes, it is not synonymous with permanent memory

emotional state w memory

heightened emotional state leads to almost instantaneous memory formation & storage

not always accurate

Rehearsal with memory

repeating information enhances memory

repeat until you remember

association with memory

you are storing in long term memory by linking something that is currently happening with something that is not even really related to it

ex. Ex. mneumonic  mechanisms

Automatic memory with association

Dumped into long term memory for no reason at all. It wasn’t something you rehearsed, associating, or have an emotional reaction too. Its just something that your brain ticked off as what you going to remember

declarative memory

Remembering factual information

memories you can consciously declare (tell someone about).

-tends to involve repetition to remember it

-type of memory that can be forgotten

-ex. Your name, address, parents names

•Involves ability to manipulate symbols & language

the conscious, intentional recollection of facts, events, and personal experiences that can be verbally described or "declared

non declarative memory

memory that acquired by doing rather than recalling

ex. never forget how to ride a bike

forms of protection for the brain

skull

meninges ‘

cerebrospinal fluid

blood-brain barrier

skull

protects brain from physical trauma

Meninges

membranes that surround and protect the brain

layers of tissue that surround the brain

what three layers make up the meninges

dura mater

periosteal layer

meningeal layer

dura mater

thickest and strongest of the three layers

most EXTERNAL layer

has 2 sub layers (periosteal and meningeal layer)

periosteal layer

attatches to inner surface of skull bones

a fibrous sheet

clings to inner surface of skull

helps hold meninges in place

lines inside of skull

meningeal layer

forms true external covering of the brain

🦴 Bread on top = Periosteal layer (stuck to the skull)

🧠 Bread on bottom = Meningeal layer (closer to the brain)

arachnoid mater

deep to the dura mater

think of it as a spider web

beneath membrane is subarachnoid space which has cerebrospinal fluid

pia mater

innermost meningeal layer

highly vascualrized

order from outside of the skull to inside of skull based on meninges

Skull ↓ Periosteal layer of dura mater ↓ Meningeal layer of dura mater ↓ Arachnoid mater ↓ Subarachnoid space (contains CSF) ↓ Pia mater ↓ Brain

cerebral spinal fluid

liquid surrounding brain and spinal cord

produced by a layer of ependymal cells in the ventricles called choroid plexus

blood brain barrier

created by tight junctions that create capillary walls

created by astrocytes surrounding the cappilary

A physical wall between the blood supply and the neurons that are found in the brain. This is important bc neurons are very sensitive to rapid environmental changes. The blood barrier provides chemical stability for the neurons.

what substances are not allowed entry into the membrane

•Bloodborne metabolic waste, protein, certain toxins, most drugs, nonessential amino acids, potassium ions

these are going to have some negative effect on neuron functioning

what are concussions

most common type of head trauma

alterations in brain functions following a physical blow to the head

neurons are still functional just not in they way they should be

what are contusions

bruising

permanent damage resulting from bruising on the brain

conduction pathway

carries impulses between the brain and the body

think of them like highways

you get on highways to get from one place to another

major reflex center

all done by the spinal cord

spinal reflexes are initated and completed at the spinal cord level. This means the brain is not directly controlling a spinal reflex. It is aware of it but the spinal cord is the one that’s actually controlling it

Conus medullaris

conus=cone

A tapered cone shaped structure where the SPINAL CORD ENDS

-spinal cord does not extend all the way down to the bottom of the vertebral column

what is the Filum terminale

fibrous extensions that extend from the conus medullaris to the coccyx