BIO 201 Exam 4 Latest updated questions and answers + rationales - Grand Canyon University

Rostral

toward the nose

Caudal

toward the tail

Major portions of the brain

Brain stem, Cerebrum, cerebellum

Cerebrum is ___% of brain volume

83

Cerebellum contains ___% of the neurons

50

The brain weighs ___ pounds

3.5

Longitudinal Fissure

separates 2 cerebral hemispheres (left/right)

Central Sulcus

Separates frontal & parietal lobe

Gyri

folds

Sulci

grooves

cortex

surface layer of gray matter

nuclei

deeper masses of gray matter

tracts

bundles of axons

gray matter

neuron cell bodies, dendrites & synapses

-forms cortex over cerebrum & cerebellum

-forms nuclei deep with in brain

white matter

bundles of axons

-forms tracts that connect parts of the brain

Meninges

Dura Mater, arachnoid mater, pia mater

Dura mater

outermost, tough membrane

-outer periosteal layer against bone

-inner meningeal layer

-subdural space (below dura mater)

-where separated from inner meningeal layer forms dural venous sinusesdraining blood from brain

supportive structures formed by dura mater

falx cerebri, falx cerebelli & tentorium cerebelli

Arachnoid mater

spider web filamentous layer

Pia mater

a thin vascular layer adherent to contours of brain

Meningitis

Inflammation of the meninges

-bacterial & virus invasion of the CNS by way of the nose & throat

-signs: high fever, stiff neck, drowsiness & intense headache which could lead to coma

-diagnose by examining the CSF fluid for bacteria

Lumbar puncture

(spinal tap) check spinal fluid

-draws fluid from subarachnoid space between two lumbar vertebrae

Lateral ventricles

found inside the cerebral hemispheres

Third ventricle

single vertical space under corpus callosum

Cerebral aqueduct

runs through the midbrain (connects 3rd & 4th ventricle)

Central canal

runs down through spinal cord

Ventricles

Internal chambers within the CNS

-lined with ependymal cells & containing choroid plexus of capillaries that produce CSF

Cerebrospinal fluid

clear liquid that fills ventricles & canals & bathes in its external surface (in subarachnoid space)

The brain produces & absorbs ___ml/day of CSF

500

Functions of CSF

Buoyancy: floats brain so its neutrally buoyant

Protection: cushions from hitting inside of skull

Chemical stability: rinses away wastes

CSF escapes from ___ to surround the brain & is absorbed by ___ into venous sinus

4th ventricle/ arachnoid villi

Circumventricular organs...

...in 3rd & 4th ventricles are breaks in the barrier where blood has direct access

-monitoring of glucose, pH, osmolarity & other variations

-allows route for HIV to invade the brain

Blood-brain & Blood-CSF barriers

Tightly joined endothelium

-permeable to lipid-soluble materials (alcohol, nicotine, O2, CO2 & anesthetics)

Hindbrain

Medulla Oblongata, Pons, Cerebellum

Medulla Oblongata

contains cardiac, vasomotor, respiratory & reflex centers which adjust heart rate but also control coughing & sneezing, etc.

-3 cm extension of spinal cord

-ascending & descending nerve tracts

-Nuclei of sensory & motor nerves (IX,X,XI,XII)

Cardiac Center (Medulla)

adjusts heart rate & force

Vasomotor Center (Medulla)

adjusts blood vessel diameter

Respiratory Center (Medulla)

controls rate & depth of breathing

Reflex Center (Medulla)

coughing, sneezing, gagging, swallowing, vomiting, salivation, sweating, movements of tongue & head

Pons

Bulge in the brainstem

-Rostral to the medulla

-Ascending sensory tracts, descending motor tracks

-pathways in & out of cerebellum

-nuclei concerned with sleep, hearing, balance, taste, eye movements, facial expression, facial sensation, respiration, swallowing, bladder control & posture (CN V, VI, VII, VIII)

Cerebellum

Evaluates sensory input (spatial perception), timekeeping center (predicts movements of objects), distinguish pitch & similar sounding words, planning & scheduling tasks.

-helps learn motor skills (memory)

-Sits atop the 4th ventricle

Cerebellar penduncles

Connects cerebellum to the brainstem

Arbor vitae

"tree of life" white matter visible in sagittal section of cerebellum

Vermis

connect left & right hemispheres of cerebellum

Folia

Parallel surface folds on cerebellum made up of gray matter

-all of output comes from deep gray nuclei

Midbrain

connects hindbrain & forebrain

-conducts signal up & down the brainstem & contains nuclei involved in motor control, pain, visual attention & auditory reflexes. (CN III, IV)

Tegmentum (midbrain)

connects to cerebellum

helps control fine movements through red nucleus

Substantia Nigra (Midbrain)

sends inhibitory signals to basal ganglia & thalamus (degeneration leads to tremors & Parkinsokns)

Central gray matter

pain awareness

Tectum

4 nuclei known as corpora quadrigemina

Superior Colliculus (Tectum)

tracks moving objects, blinking, pupillary & head turning reflexes

Inferior Collilulus (Tectum)

Reflex turning of head to sound

Reticular Activating System

Clusters of gray matter scattered throughout pons, midbrain & medulla

-Regulates: balance & posture, sleep & conscious attention (injury leads to irreversible coma)

-includes cardiac & vasomotor centers

-origin of descending analgesic pathways (pain modulation)

Habituation (reticular formation)

ignoring repetitive, inconsequential stimuli

Diencephalon/Forebrain

Thalamus (2 thalami, 4/5 of diencephalon, 23+nuclei)

Hypothalamus

Epithalamus

Thalamus (Diencephalon)

Oval mass of gray matter protrudes into lateral ventricle & 3rd ventricle

-Receives nearly all sensory info on its way to cerebral cortex

-Relays signals from cerebellum to motor cortex

-Memory & emotional functions (limbic system)

Hypothalamus (Diencephalon)

-walls & floor of 3rd ventricle

-Functions: hormone secretion, ANS control, thermoregulation, food/water intake (hunger & satiety), sleep/circadian rhythym, memory (mammillary bodies), emotional behavior

Epithalamus (Diencephalon)

composed mainly of the Pineal Gland (secretes seratonin & melatonin) & the habenula (connects limbic system to the midbrain)

Cerebral cortex

3mm layer of gray matter w/ extensive folds to increase surface area

Cerebrum is divided into ___

lobes (frontal, parietal, occipital, temporal)

Frontal lobe

voluntary motor functions

planning, mood, smell & social judgement

Parietal Lobe

Receives & integrates sensory info

Occipital Lobe

Visual center of the brain

Temporal Lobe

Areas for hearing, smell, learning, memory & emotional behavior

Most of cerebrum is ___ matter

white

Projection tracts (Cerebral white matter)

from brain to spinal cord

Commissural [visual] tracts (Cerebral white matter)

cross to opposite hemispheres (corpus callosum, anterior/posterior commisures)

Association Tracts (Cerebral white matter)

connect lobes & gyri w/ in a hemisphere

Basal nuclei

masses of gray matter deep to cerebral cortex

receives input from substantia nigra & motor cortex

plays a role in motor control & tremors

Limbic system

Loop of cortical structures surrounding deep brain (amygdala, hippocampus, fornix & cingulate gyrus)

Hippocampus (limbic)

important in memory

important in organizing sensory & cognitive info into a memory

Amygdala (limbic)

important in emotion

important in emotional memory

Electroencephalogram

records voltage changes from postsynaptic potentials in cerebral cortex

Differences in ___ & ___ distinguish four different types of brain waves

amplitude/ frequency

Brain waves

states of consciousness that can be correlated w/ EEG (4 types: alpha, beta, theta, delta)

Alpha brain waves

occur when awake & resting w/ eyes closed

Beta brain waves

occur w/ eyes open performing mental tasks

Theta brain waves

occur during sleep or emotional stress

Delta brain waves

occur during deep sleep

Sleep

temporary state of unconsciousness; controlled by hypothalamus, reticular formation thalamus & cerebral cortex

Sleep paralysis

inhibition of muscular activity

Suprachiasmatic nucleus

acts as a biological clock to set circadian rhythym

Restorative effect (sleep)

Brain glycogen levels increase

memories strengthened (synoptic connections reinforced or eliminated)

4 stages of Non-REM sleep

(occurring in the first 30-45 minutes of sleep)

#1 is a drifting sensation (would claim was not sleeping)

#2 still easily aroused

#3 [reached in 20 mins] vital signs change: BP, pulse & breathing rates drop

#4 is deep sleep, difficult to arouse

REM sleep occurs about ___ times a night

five

REM sleep

rapid eye movements under the eyelids, vital signs increase, EEG resembles awake person, dreams & penile erections occur

-may help sort & strengthen info from memory

Cognition

Such as awareness, perception, thinking, knowledge & memory

Association areas = ___% of brain tissue

75

-integration of sensory & motor info occurs

Contralateral neglect syndrome

brain lesion- parietal

unaware of objects or limbs on one side of body

Agnosia

brain lesion- temporal

inability to recognize objects

Prosopagnosia

brain lesion- temporal

inability to recognize faces

brain lesion-frontal

problems with personality (phineas gage)

inability to plan & execute appropriate behavior

Phineas Gage

spike through frontal lobe Ventromedial region of both frontal lobes

personality change

prefrontal cortex functions: planning, moral judgement, emotional control

Pathological inability to forget (memory)

Have trouble w/ reading comp

Anterograde amnesia

Can not store new data

Retrograde amnesia

can not remember old data

Lesion- Hioppocampus

causes inability to form new memories

Emotion

form in hypothalamus & amygdala

-artificial stimulation produces fear, anger, pleasure, love, parental affection, etc.

___ ___ controls how emotions are expressed (seat of judgement)

Prefrontal Cortex

Somesthetic Sensation

comes from receptors widely distributed throughout the body (touch, pain, pressure, stretch, movement, heat, cold)

somatosensory area is postcentral gyrus