Central Nervous System

what are the four major regions of the adult brain

• cerebral hemispheres

• diencephalon

• brain stem

• cerebellum

what does the diencephalon contain

• thalamus

• hypothalamus

• epithalamus

what does the brain stem contain

• midbrain

• pons

• medulla oblongata

where is the cerebellum located

located dorsal to the pons and medulla

name the four brain ventricles

• lateral

• third

• fourth

• cerebral aqueduct

describe the locations of the four brain ventricle and their connecting channel

• Lateral: paired cavities deep within each cerebral hemisphere

• Third: a slit-like cavity enclosed by the diencephalon

• Fourth: located in the brain stem, anterior to the cerebellum

  • Cerebral Aqueduct: midbrain channel connecting the third and fourth ventricles

Locate and define the primary functions of the motor areas in the cerebral cortex

• Primary motor cortex: located in precentral gyrus; controls percise, skilled skeletal muscle movements

• Premotor cortex: anterior to precentral gyrus; plans learned, patterned motor skills

• Broca’s Area: typically left hemisphere; directs muscle movements for speech production

• Frontal eye field: control voluntary eye movements

distinguish between primary somatosensory cortex and the somatosensory association cortex

• Primary Somatosensory Cortex: located in postcentral gyrus; receives spatial info from skin and proprioceptors

• Somatosensory Association Cortex: integrates sensory inputs to determine size, texture, and object relationships

list the six specialized sensory cortices and the three multimodel association areas

• Sensory cortices:

  • visual (occipital)

  • Auditory (temporal)

  • olfactory (smell)

  • Gustatory (taste)

  • Visceral sensory (organs)

  • Vestibular (balance)

• Multimodel areas:

  • Anterior (prefrontal cortex for cognition)

  • Posterior (pattern/language)

  • Limbic (emotion/memory)

define cortical lateralization and describe how functional specialties differ between the hemispheres

Lateralization: division of labor between the nearly identical hemispheres

Cerebral Dominance: the hemisphere dominant for language

Left Hemisphere: specialized in language, math, and logic

Right Hemisphere: specialized for visual-spatial skills, intuition, emotion, and arts

Control Rule: contralateral control maps each hemisphere to the opposite side of the body

what are the three subdivisions of the diencephalon

• Thalamus

• Hypothalamus

• Epithalamus

what is the primary function of the thalamus

acts as the sorting and relay gateway to the cerebral cortex

what is the primary function of the hypothalamus

• main visceral control and homeostasis center

• regulates vitals, temp, hunger, sleep-wake cycles, and endocrine system

what is the primary function of the Epithalamus

• forms roof of third ventricle

• contains the pineal gland which secretes melatonin

what are the subdivisions of the brain stem

• Midbrain

• Pons

• Medulla Oblongata

what is the function of the midbrain

• contains cerebral peduncles and corpora quadrigemina

  • superior colliculi for visual reflexes

  • inferior colliculi for auditory relays

what is the function of the pons

• relays info between motor cortex and cerebellum

• maintains normal breathing rythms via reticular nuclei

what is the function of the medulla oblongata

• autonomic reflex center

  • housing cardiovascular (heart rate/vessel diameter)

  • respiratory rhythm centers

describe the anatomy and core functions of the cerebellum

• accounts for 11% of brain mass, features symmetric hemispheres, a midline vermis, folia (ridges), and arbor vitae (white matter)

• Function: processes synchronized inputs from cortex, brian stem, and receptors to allow smooth, coordinated skeletal movements

what is the location and role of the limbic system

• Location: medial aspects of cerebral hemispheres and diencephalon, encircling the upper brain stem

• Functions as the “emotional or affective brain”

what does the amygdaloid body do in the Limbic system

assesses danger, recognizes fear/anger expressions, and elicits fear

what does the cingulate gyrus do in the Limbic system

resolves mental conflicts and expresses emotions physically

what is the Limbic systems role when it comes to memory linking

interacts with prefrontal lobes, hippocampus, and amygdala to process memory

what is the location and function of the Reticular function

• Location: three broad neural columns (Raphe, medial, lateral) running the entire length of the brain stem

• function: governs brain arousal and alertness via the reticular activating system (RAS)

• filtration: screens out roughlt 99% of repetitive, familiar, or weak sensory stimuli

• suppression: inhibited by sleep centers, alcohol, and tranquilizers; severe damage causes a permanent coma

define an EEG and name the four types of brain waves

diagnostic recording of continuous electrical activity by measuring potential differences between cortical regions

• alpha

• beta

• theta

• delta

define alpha waves of an EEG and what its range is

• 8-18 Hz

• regular

• rhythmic

• low-amplitude

• indicates a calm, relaxed awake brain

define beta waves of an EEG and what its range is

• 14-30 Hz

• rhythmic

• less regular

• dominate during active mental concentration

define theta waves of an EEG and what its range is

• 4-7 Hz

• irregular

• common in children

• uncommon in awake adults unless sloving very difficult tasks

define delta waves of an EEG and what its range is

• <4 Hz

• high-amplitude

• characteristics of deep sleep/anesthesia

• indicates brain damage if awake

compare the events and physiology importance of slow-wave (NREM) and REM sleep

• NREM

  • sleepers cycle through stages 1-4 in 30-45 minutes; delta waves dominate as vital signs drop

  • physically restorative; stage 4 declines with age

• REM

  • begins abruptly 90 minutes into sleep; features rapid eye movements, awake-like EEG, and skeletal muscle paralysis

  • mental reverse-learning to purge superfluous data; deprivation causes moodiness and depression

distingush between STM and LTM, and list the factors enhancing memory transfer

• STM

  • temporary holding zone limited to 7 or 8 pieces of data

• LTM

  • limitless storage split into declarative (explicit facts) and nondeclarative (unconscious skills/habits)

• Transfer factors

  • emotional state (alert/motivated)

  • rehearsal (repetitive)

  • association (tying new data to old memories

• autonomic memory

  • subconscious data that bypasses active systems to store directly in LTM

what are the three layers of the meninges

• dura mater

• arachnoid mater

• pia mater

describe the dura mater

strongest, double-layered, fibrous outermost sheet

describe arachnoid mater

middle web-like layer separated from the dura by the subdural space

describe that pia mater

delicate, high vascuralized deepest layer clinging tightly to brain

detail the production of CSF

generated constantly by choroid plexuses hanging from ventricle roofs

detal the circulation of CSF

fills subarachnoid space and central cavities; 150 mL volume is replaced every 8 hours

detail the reabsorption of CSF

drains back into blood via arachnoid villi protruding into the superior sagittal sinus

what is CSF made of

watery cushion derived from blood plasma with less protein and unique ion levels

explain the permeability characteristics of the Blood-Brain barrier

• high selective metabolic barrier isolating neurons from bloodborne fluctuations

• facil

• facilitated diffusion of nutrients; unrestricted passage of fat-soluble items (alcohol, nicotine)

• denies entry of metabolic wastes, proteins, potassium ions, and most drugs

• absent in blood-monitoring areas like the vomiting center and hypothalamus

contrast mechanical brain injuries: concussion, contusion, hemorrhage, and edema

• contusion: traumatic head injury causing permanent, irreversible structural tissue damage

• consussion: temporary, transient alteration in brain performance following trauma

• aubdural/subarachnoid hemorrhage: internal bleeding causing localized pressure; risks forcing the brain stem through the foramen magnum

• cerebral edema: dangerous tissue swelling triggered by traumatic inflammatory responses

describe the pathology of CVAs

cerebral artery blockage causes ischemia; worsened by glutamate acting as an excitotoxin; results in hemiplegia

describe the pathology of Alzheimer’s

progressive dementia’ beta-amyloid plaques and neurofibrillary tangles destroy transport, causing brain shrinkage

mechanisms and symptoms of Parkinson’s disease

degeneration of dopamine neurons in the substania nigra; hyperactive basal nuclei resting tremors, rigidity, akinesia and postural instability

mechanisms and symptoms of huntington’s disease

fatal hereditary disorder; mutant huntingtin protein destroys basal nuclei and cortex; causes wild, jerky “flapping” movements and severe mental decay

describe the gross extent of the spinal cord

extent: begins at foramen magnum; ends inferiorly at L1 or L2 vertebra level

describe the gross anchorage of the spinal cord

epidural space filled with fat cushion and veins; dural/arachnoid pockets extend to sacrum

describe the gross external features of the spinal cord

emerges into 31 pairs of spinal nerves; features cervical/lumbosacral an enlargements and ends in the cauda equina

core layout of gray matter of the spinal cord

H-shaped gray matter surrounding the central CSF canal, linked by the gray commissure

describe the dorsal horns of the spinal cord

composed of interneurons receiving incoming visceral and somatic sensory input

describe the ventral horns of the spinal cord

house of somatic motor neurons whose axons exit via ventral roots to command skeletal muscles

describe the lateral horns

present only in thoracic ad superior lumbar regions; house autonomic sympathetic motor neurons