BIOL 2220 exam 4

embryonic development of brain

1. flat piece of ectodermal tissue thickens along the midline to form the neural plate

2. neural plate folds inward, invaginate, to form the neural grooves (regions on sides of the grooves are called neural folds)

3. neural folds come together and fuse to form a continuous hollow tube that runs the length of the embryo called the neural tube

4. tube detaches and moves toward the middle of the embryo

5. neural crest develop as offshoots of neural folds and will give rise to neural ganglia

6. hollow tubes starts to differentiate through cephalization- the caudal end will swell and form primary brain vesicles and becomes the adult brain and the rest of the tube will remain as spinal cord

primary brain vesicles: prosencephalon

part that will develop into the adult forebrain

- great amount of change that occurs

- areas associated with intellect and cognition

primary brain vesicles: mesencephalon

part that will develop into the adult midbrain

- no change (stays the mes)

primary brain vesicles: rhombencephalon

part that will develop into the adult hindbrain

- least amount of change

secondary brain vesicles: telencephalon

- from prosencephalon

- cerebrum

secondary brain vesicles: diencephalon

- from prosencephalon

- hypothalamus, thalamus and epithalamus

secondary brain vesicles: metencephalon

-from rhombencephalon

- pons and cerebellum

secondary brain vesicles: myelencephalon

- from rhombencephalon

- medulla oblongata

mesencephalon does not differentiate into secondary brain vesicle: gives rise to the ??

midbrain

brain stem =

midbrain, pons, medulla

brain stem takes care of ???

low brain functions like breathing and digestion

brain vesicles arise from the ??? of neural tube

lumen

(mustbe connected with one another and with the central canal of the spinal cord- lumen of the spinal cord is the central canal

brain ventricles are filled with ??

cerebrospinal fluid

cerebrospinal fluid provides

protection and cushion/ bouncy to the brain

brain vesicles are lined with

glial cells= ependymal

Lateral ventricles (tele)

one within each hemisphere of the cerebrum

- septum pellucidium separates the two lateral ventricles from one another

- connected to one another via the intraventricular foramen

- allows transfer of fluid between ventricles

- intraventricular foramen also connects the lateral ventricles to the 3rd ventricle

third ventricle (di)

connects the 4th ventricle via the cerebral aquaduct

fourth ventricle

continuous with the lumen of the spinal cord

connecting channels

-intraventricular foramen: connects the lateral ventricles to each other and to the 3rd ventricle

-cerebral aquaduct: connects the 3rd ventricle to the 4th ventricle

openings

-lateral apertures: 2 openings on the side of the 4th ventricle

- median aperture: one opening on the top of the 4th ventricle

- important so the brain will float and not get crushed

gyri

bumps on the brain

sulci

depressions on the brain

longitudinal fissure

very deep depression which separates the cerebrum into the left and right hemispheres

transverse cerebral fissure

fissure along the back of the brain

tremendous division of ?? in the brain

labor

lobes of the cerebrum

lobes separated by sulci

- frontal: front portion

- parietal: middle portion

- temporal: on either side

- occipital: back portion

- insula: within

functional regions of the cerebrum: cortex

superficial

- gray matter

- neuronal bodies

- unmyelinated axons

functional regions of the cerebrum: white matter

middle

- myelinated axons bundled together

- lipid= white

functional regions of the cerebrum: basal nuclei

deep

dark patches with in the white matter

cerebral cortex called =

the conscious mind

involved in: self awareness, sensation, communication, memory, voluntary movement

cerebrum thickness

2-4mm

- differing degress of thickness and structure in different parts of the cerebrum

cerebral cortex lateralization of function

- each hemisphere controls the opposite side of the body

- right side controls left hand etc

- our brain doesnt start with one side dominant- it shifts through development and ultimately one side becomes dominant

- dominant side is linked to dom eye and dom eye linked to dom hand

left side of brain

controls logic, math, science and some language

right side of brain

responsible for visual spatial orientations, art, music, emotion and intuition

no areas acts alone

even though its divided, individual parts do not act on their own

- interneurons connect different parts to another

functional areas of cerebral cortex: motor

involved with voluntary movement

-front half

- ex: walking- skeletal muscle contraction is completely separated from smooth and cardiac muscle contraction

functional areas of cerebral cortex: sensory

involved with conscious awareness of sensation

- detects stimuli

-back half

functional areas of cerebral cortex: association

communication areas between sensory and sensory, between motor and motor and between sensory and motor parts

all neurons in cerebral cortex are ??

interneurons which are multipolar

-sensory areas receive from sensory neurons and motor areas send to motor neurons

motor areas

cause movement of skeletal muscle

- send signals away from the brain

primary motor cortex

- center of brain

- pyramidal cells

- involved with precise movement of skeletal muscle

premotor cortex

associated with learned motor skills

- often repeated patterns

- writing, typing, playing instrument

- functions through the primary motor cortex

broca's area

left hemisphere

- controls the muscle that are used for speech

frontal eye field

sends messages to allow the voluntary movement of the eye

- right side controls opposite

primary somatosensory cortex

- behind the the central sulcus

- receives signals from sensory receptors on the skin and proprioceptors for balance

-gives us spatial discrimination

- helps use figure out which part of the body is being stimulated

somatosensory association cortex

linked directly to the primary somatosensory cortex

- integrates info that is receives from the primary somatosensory cortex

visual areas

- primary visual cortex: receives info from retina

- visual association area: interprets info from retina and uses prior experiences

auditory areas

-primary auditory cortex: receives info from inner ear

- auditory association area: interprets info from the inner ear

olfactory cortex

receives info from oder detectors in nose

-memories can be formed from oder easily

gustatory cortex

receptions of taste

vestibular cortex

related to balance

- in the insula

prefrontal cortex

more developed in humans

- associated with personality, intellect, recall, cognition

- develops more slowly than other brain parts

- development is dependent upon social feedback

language areas

for language comprehension

-wornicke's area used when we sound out words

- left hemisphere

- areas on the right side in the same place as these areas are associated with things like body language

general interpretation area

- left hemi

- receives sensory input from all other sensory association areas

- integrates all of this input into a single thought

visceral association area

conscious perception of visceral sensations

- ex upset stomach

- has link to speech

cerebral white matter

- deep to the cortical gray matter

- carries communication between areas of the cerebrum

- carries communication between the cortex and lower CNS centers

- myelinated fibers get bundles into large tracts

commissures

connect the left and right sides of the cerebrum

- gray matter to gray matter

- largest of the tracts

- the largest of the commissures is called the corpus callosum

association fibers

connect different parts of the same hemisphere

- left side to left side or right side to right side

projection fibers

enter or leave the cerebrum from lower brain areas or the spinal cord

- tie the cerebral cortex to the rest of the nervous system

- link between receptors and effectors

basal nuclei

part of the cerebrum

- islands of gray matter within white matter

basal nuclei function

these dont have direct access to motor pathways, they have to go through the thalamus

- involved with fine tuning or regulating motor activity and function like the cerebellum

- involved with regulating attention, cognition and stereotype movement

parkinsons disease

when basal nuclei dont function properly

types of basal nuclei

- caudate nucleus

- putamen

- globus palidus

^ these 3 function to regulate motor activity

-amygdala: linked to limbic system, deals with emotion

thalamus

- gateway to cerebral cortex

- this is a structure of the diencephalon

- contains several nuclei, each with their own function and each of these parts connect to a different part of the cerebrum

- all sensory is sent to the thalamus first

- also all non sensory inputs- sorts the input and sends to the appropriate area of the cerebral cortex

hypothalamus

- visceral control center- control center for organs- important in homeostasis

hypothalamus

- visceral control center

- control center for organs

- important in homeostasis

hypothalamus functions

- regulates ANS activity: involuntary and subconscious

- heart rate and breathing

- controls emotional responses: linked to the limbic system & bio rhythm (sleep-wake and related to mood)

- regulates body temperature: determines the thermostat set point for our bodies- fever

- controls food intake: involved with hunger sensation

- regulates water balance: detected by kidneys to help maintain blood pressure

- controls sleep-wake cycle

- bio rhythm

- regulates hormone release: regulates the endocrine system- this is a chemical link

epithalamus

- contains pineal gland: secretes a chemical called melatonin

- melatonin functions in the sleep-wake cycle

- this gland responds to UV light

- during day light the pineal gland activity is inhibited and as soon as the sun sets, the gland is activated and begins to secrete melatonin

- has affect on mood

- produces cerebrospinal fluid: fluid found in spinal cord and brain, produced by ependyma, continually replaced

brain stem composition

= midbrain + pons + medulla

- composed of deep gray matter, surrounded by white matter

- also has pockets of gray matter embedded within white matter

- this is important because it distinguishes where the brain stops and the spinal cord stops

brain stem functions

-provides programmed automatic behaviors needed for survival

- controls

- breathing, blood pressure, heart rate

- connects the higher and lower brain centers

- info passes here to get to the brain and to get to the body

mid brain

contain motor tracts to connect to the spinal cord

- these tracts are part of the pyramidal system

- also has tracts that connect to the cerebellum

mid brain functions

- pain suppression

- serves as a link between amygdala and ANS

- controls fight or flight through motion

- contains the visual reflex center

- this coordinates eye movement with head movement

- auditory relay

- sensory info passes through the ear into the midbrain

- corpora quadrigemina: part of midbrain that contains visual and auditory relay

pons

mainly composed of conduction tracts

- functions:

- complete pathway between higher brain centers and the spinal cord

- relays info between the motor cortex and the cerebellum

medulla oblongata

- major autonomous reflex center

- medulla controls the reflexes while the hypothalamus regulates them

- makes the actions happen

medulla oblongata function

- controls heart rate and blood vessel diameter

- controls rate and depth of breathing

- regulates vomiting, hiccuping, sneezing, coughing and swallowing

cerebellum

functions:

- refines skeletal muscle contractions

- plays a role in cognition, language and problem solving

- activity occurs subconsciously

- receives inputs from other brain regions and coordinates all inout to form a place that makes it all happen

cerebellum composition

-composition similar to the cerebrum

- contains superficial gray cortex and deep white matter masses

- arbor vitae: the arrangement of the white matter

cerebellar processing

1. motor association area of the cerebral cortex sends signals to the cerebellum

2. cerebellum receives the info from visual receptors, equilibrium receptors, and proprioceptors

3. cerebellar cortex calculates the best way to coordinate force of contraction

4. cerebellum sends message to the cerebral cortex

5. cerebral cortex sends a signal to the muscle to allow contraction of skeletal muscle

functional brain systems

network of neurons that work together and span large distances of the brain

- cannot be localized to specific regions of the brain

- different places in the brain work together

limbic system

- emotional brain: strong link between thoughts and feelings

- helps us resolve mental conflict

- we can express emotions as movement

- emotional overrides logic

- we respond to emotion before we do logic

- fight or flight

- elicits fear

- receives inout from cerebrum and diencephalon

-closely linked with rhinencephalon

- olfactory link

- memory is closely linked with strong smells

- output is relayed through hypothalamus

- emotion can affect the hormones being released

reticular formation

- loosely clustered neurons in the center of midbrain, pons and medulla

- governs arousal or brain as a whole

- acts as an alarm clock of the body

- reticular activation system RAS filters sensory input

- this determines when we awake, when awake the RAS sends constant signals to the cerebrum to keep the cerebral cortex active

brain waves

pattern of neuronal electrical activity

- recorded in an EEG

brains wave: alpha wave

8-13 waves/sec

- idle brain brain, awake but not doing anything

- during the day we have alpha and beta waves that we bounce between

brain wave: beta

13 waves/sec

- when focuses and concentrating on something

- during the day we have alpha and beta waves that we bounce between

brain wave: theta

4-8 waves/sec

- in children

brain wave: delta

less than 4 waves/sec

- deep sleep

- these when awake note brain damage

consciousness

awareness of sensation and control of movement

LOC (level of consciousness)

-most active mean most control of the body

- alert

- drowsy

- lethargic

- stupper

- coma

- least active means no control of activity

sleep

you can be aroused from sleep but not from a coma

- a state of partial unconsciousness

non REM sleep

restorative sleep

-when the body recovers and replenishes stores of glucose and oxygen

- delta waves

- lasts about 90 min then interrupted by REM

REM sleep (rapid eye movement)

rem= a lot of twitching

- occurs after non rem

- this is when we dream

- allows us to analyze the day

- reverse learning: differentiate non important info from important info so we can learn and retain more

memory

storage and retrieval of info

- consists of linked neural connections

-pathway: stimulus occurs, stimulus goes into temporary storage buffer, if not used its lost and if used it goes to short term memory

- short term memory: gateway to long term memory

- things in long term memory can be lost

factors affecting long term memory

- rehearsal: dependent on mood and linking it to something you already know

- association: reduces the amount of rehearsal time that is necessary

- mood/ emotion: the happier we are, the faster it goes into long term memory

- automatic memory: set of circumstances that results in info immediately moving into long term memory

protection of the brain: bone

skulls surrounds the brain

- flat compact bone with spongy center

protection of the brain: membranes

thick and fibrous

- called meninges

protection of the brain: fluid

contained within the membrane

- specifcally, cerebrospinal fluid

protection of the brain ++

skin and hair play a role in protecting and cushioning

meninges

cover and protect the CNS: both brain and spinal cord

- protect blood vessels which are supplying the nervous tissue

- contain cushioning cerebrospinal fluid

- 3 layers

meninges: dura mater

-composed of fibrous ct

- 2 layers in the brain

- periosteal layer (superficial) which attaches to the skill and holds it in place and a deep layer

- single layer in the spinal cord

- strongest and most superficial covering of the CNS

- under this is subdural space and also has cerebrospinal fluid

meninges: arachnoid

middle layer

- creates subarachnoid space which is filled with cerebrospinal fluid

- blood vessels also run here

meninges: pia mater

- deepest of the meninges

- immediately covers the brain and spinal cord