A&P Ch. 12

Dura mater

"Tough mother" most external, strongest, 2 layers of fibrous CT-1. Periosteal 2. Meningeal.

Thalamic functions

"Gateway to cerebral cortex" filters, sorts, edits, and relays information coming into cerebral cortex (not all info is forwarded)-ex: Thalamus filters out sights and sounds in cafeteria when you are trying to study. Afferent sensory impulses from all senses (except olfaction) and all parts of the body converge and synapse in thalamus. Mediates sensation, motor activities, cortical arousal, learning, and memory.

Blood-brain barrier (4)

1. Regulates which substances can and can't enter the interstitial fluid of the brain, 2. maintains stable environments, 3. prevents exposure of brain to neurons to waste products in blood and variations of normal substances-(hormones, ions, and amino acids), and 4. chemical variations and harmful substances could adversely affect brain function.

4 ventricles of the brain

2 C-shaped lateral ventricles, third ventricle, and fourth ventricle.

Space restriction on brain development

2 flexures form and cause forebrain to angle posteriorly toward brain stem, cerebral hemispheres grow posteriorly and laterally-envelop diencephalon and midbrain, cerebral hemispheres surfaces creases and folds into convolutions-allow for more neurons in space.

Thalamus

80% of diencephalon. Masses of gray matter (nuclei) form superolateral walls of the third ventricle, connected by interthalamic adhesion. Nuclei project and receive fibers from cerebral cortex.

Reticular formation

A network of nerve fibers located in the center of the medulla that helps regulate attention, arousal, and sleep; also called the reticular activating system. Has motor and sensory components.

Spatial discrimination

Ability of neurons to identify body region being stimulated.

Lesions of Wernicke's area

Able to speak, "word salad"-nonsense words and sentences, have difficulty understanding language.

Levels of consciousness

Alertness, drowsiness, stupor, coma.

Periosteal layer

Attached to inner periosteum of skull, doesn't extend to spinal cord.

Inferior colliculi

Auditory relay centers-transfer information from receptors in ear to sensory cortex, act in "startle reflex" to sudden sound.

Subarachnoid space

Between arachnoid mater and pia mater. contains weblike extensions, CSF, and cerebral blood vessels.

Corticospinal tracts

Carry motor signals from cerebrum to brainstem and spinal cord.

Higher mental functions

Consciousness, sleep, language, and memory. Higher mental functions involve continuous electrical activity of neurons.

Damage to posterior association area

Damage - may refuse to wash or dress opposite side of body because don't recognize it as "self"

Damage to primary motor cortex

Damage to localized areas of PMC paralyzes body muscles controlled by those areas. • Paralyzes muscles on opposite side of body • Only voluntary control is lost • Example - stroke (cerebrovascular accident), Blood circulation to a brain area is blocked, Brain tissue dies.

Damage to prefrontal cortex

Damage to this area can cause: personality change, recklessness, or poor judgment/reasoning.

Damage to premotor cortex

Damage would cause decrease in speed, accuracy, agility of typing but would not impair movement. Skill could be "relearned"

Fissure

Deep groove separating large regions of brain.

Alcohol intoxication impairs cerebellar function

Disturbance of gait, loss of balance/posture, inability to detect proprioceptive info.

Central canal of the neural tube

Extends throughout the brain and spinal cord.

Think FAST

Face drooping, Arm weakness, Speech difficulty, Time to call 911.

Huntington's disease

Fatal hereditary disorder, during middle age. • Abnormal protein huntingtin accumulates in brain cells • Leads to massive degeneration of the basal nuclei and cerebral cortex • Wild, jerky, flapping movements (chorea), mental deterioration, death in 15 years

Cerebrospinal fluid

Found in and around brain and spinal cord, circulates in ventricles and subarachnoid space, some moves in central canal. Formed from blood plasma. Clear watery solution.

Temporal lobe functions

Hearing and smell-interpretation and storage.

Tentorium cerebelli

Horizontal dural fold over cerebellum, in transverse fissure between cerebrum and cerebellum.

Right hemisphere

Imagination, visual-spatial skills, intuition, emotion, artistic skills, and musical skills. More free-spirited, creative, poetic, insightful.

Subdural or subarachnoid hemorrhage

Increases intracranial pressure, compresses brain tissue, may force brain stem through foramen magnum, resulting in death.

Meningitis: symptoms and cause

Inflammation of meninges. Fever, headache, vomiting, stiff neck. Caused by viral or bacterial infection-bacterial meningitis is most severe. Spreads rapidly through respiratory or oral secretions, may result in brain damage or death.

Association areas

Integrate and store information. Anterior, posterior, and limbic.

Traumatic brain injuries

Involve localized injury at site of blow (coup injury), ricochet injury on opposite side of skull (countrecoup injury).

Corpus callosum

Largest connecting tract.

Cerebellar injury results in

Loss of muscle tone and clumsy unsure movements.

Tissue plasminogen activator TPA

Only approved treatment for stroke, dissolves blood clots in brain.

Mammillary bodies

Paired anterios nuclei that bulge from hypothalamus, olfactory relay stations.

Cerebrovascular accidents (CVAs)

Stroke. Single most common nervous system disorder, third leading cause of death in North America. Ischemia. Most common cause of CVA = blockage of a cerebral artery by a blood clot. TIAs.

Concussion

Temporary alteration in function.

Forgetting

The inability to retrieve stored info.

Memory

Storage and retrieval of information. 2 stages of storage: short-term memory and long-term memory.

Hippocampus and parahippocampal gyrus

Stores memories and forms long-term memory.

Absence seizures

• Mild seizures seen in young children • Blank expression for few seconds

Hydrocephalus

"Water on the brain" increased amount of CSF, caused by obstruction of CSF flow or reabsorption. Newborn baby-enlarged head because skull bones haven't fused yet, increasing fluid compresses blood vessels to brain and damages brain tissue. Shunts drain excess CSF.

Cerebral edema

Swelling of the brain.

Trace the flow of CSF formation

1. CSF is secreted by lateral ventricle choroid plexuses. 2. CSF flows though interventricular foramina into third ventricle. 3. Third ventricle choroid plexus adds more CSF. 4. CSF flows through cerebral aqueduct to fourth ventricle. 5. Fourth ventricle chorioid plexus adds more CSF. 6. CSF flows out median aperture and two lateral apertures. 7. CSF fills subarachnoid space-bathes external surfaces of brain and spinal cord. 8. CSF is reabsorbed by arachnoid villi into dural venous sinuses. 9. Venous blood of dural venous sinuses drains into the internal jugular veins.

What are 7 functions of the hypothalamus?

1. Controls autonomic nervous system, 2. center for emotional response, 3. regulates body temp, 4. regulates food intake, 5. regulates water balance and thirst, 6. regulates sleep and sleep cycle, and 7. functions in the endocrine system.

What 3 layers make up the BBB?

1. Endothelium of capillary walls-tight junctions, least permeable capillaries in the body. 2. Basal lamina (basement membrane) surrounds capillaries. 3. Perivascular feet of astrocytes-cling to and envelop capillaries, provide signals to capillary endothelial cells causing tight junctions.

Functions of CSF

1. Gives buoyancy to the brain, reduces brain weight, prevents brain from crushing under its own weight, liquid cushion to protect CNS from sudden movements or forces. 2. Nourishes brain and removes waste products, carries chemical signals from one part of brain to another (hormones, sleep, and appetite molecules).

Meninges: layers

3 connective tissue membranes between the brain and cranium, 3 layers-dura, arachnoid, and pia mater.

4 things about the cerebral cortex

3 functional areas, Contralateral, Lateralization, Complex functions.

Unconsciousness

A signal that brain function is impaired • Fainting or syncope-brief loss of consciousness • Inadequate cerebral blood flow due to low blood pressure • Hemorrhage, sudden emotional stress

Epileptic seizures

Absence seizures and tonic-clonic seizures. Some sufferers experience hallucination before seizure begins-Aura of tastes and smells, flashes of light.

BBB is selective

Allows movement of nutrients into brain by facilitated diffusion (glucose, amino acids, electrolytes). Prevents metabolic wastes, proteins, toxins, most drugs, K ions from entering brain. Allows any lipid-soluble substance to pass into interstitial fluid of the brain (O, CO2, fats, alcohol, nicotine, caffeine, anesthetics).

Natural circadian rhythm

Alternating cycles of sleep and wakefulness.

Basal nuclei islands of gray matter

Analyzes incoming word sounds, produces outgoing word sounds and grammatical structures.

Broca's area: location and function

Anterior to inferior region of premotor cortex, Present in one hemisphere (usually the left), special motor speech area that directs muscles of the tongue for speech production-active for speech, and active when thinking or planning voluntary motor activities.

Premotor cortex: location and function

Anterior to precentral gyrus, controls learned, skilled, repetitious, patterned motor activities ex: Playing musical instrument, typing. Coordinates simultaneous movements of several muscle groups (to help plan movements) = "choreographer" sends impulses to primary motor cortex, supplies its own pyramidal tract fibers to spinal cord. Involved in planning of movements that depend on sensory feedback.

Frontal eye field

Anterior to premotor cortex and superior to Broca's area. Controls voluntary eye movements ex: Reading and coordinating binocular vision.

Three parts of MAS

Anterior, posterior and limbic association areas.

3 lobes of the cerebellum

Anterior, posterior, and flocculonodular.

Pia mater

Areolar CT. Clings to brain.

Subdural space

Between dura mater and arachnoid mater.

Epidural space

Between skull and dura mater.

Ischemia

Blood circulation is blocked to a brain area and brain tissue dies.

3 important regions of left cerebral cortex

Broca's area, Wernicke's area and basal nuclei.

Contusion

Bruising and permanent damage. Severe brainstem contusions cause coma.

Lesions of Broca's area

Can understand language, have difficulty speaking, sometimes writing.

Autonomic nuclei of medulla oblongata

Cardio, vasomotor, and respiratory center.

Ventricles

Cavities or expansions of the brain derived from lumen of embryonic neural tube. Connected to one another and to central canal of spinal cord. Lined by ependymal cells and contains CSF.

Medulla oblongata

Central canal continues into medulla • Broadens to form the fourth ventricle-medulla and pons form ventral wall of fourth ventricle. • Pyramids - two longitudinal ridges on ventral medulla • Pyramidal (corticospinal) tracts descending from motor cortex, Decussation of the pyramids.

Spinal cord

Central cavity surrounded by a gray matter core, external white matter composed of myelinated fiber tracts.

Arbor vitae

Cerebellar white matter. Branched, tree-like appearance. It brings sensory and motor information to and from the cerebellum.

Midbrain

Cerebral peduncles - "little feet of the cerebrum", "pillars" that "hold up" the cerebrum. Contain pyramidal (corticospinal) motor tracts. Superior cerebellar peduncles-connect cerebellum to midbrain. Cerebral aqueduct runs through midbrain-connects third and fourth ventricles.

What are the 4 adult brain regions?

Cerebrum, diencephalon, brain stem, and cerebellum.

Secondary brain vesicles

Cerebrum, thalamus, hypothalamus, epithalamus, retina, midbrain, pons, cerebellum, and medulla oblongata.

BBB may be reduced or missing in...

Choroid plexuses (reduced), hypothalamus (missing), vomiting center of brain stem (missing), newborn and premature infant brain (incomplete), brain injury may result in localized breakdown of BBB.

Production of CSF

Choroid plexuses produce CSF, blood plasma filters from capillaries to ependymal cells, ependymal cells modify filtrate, choroid plexuses also help cleans CSF by removing wastes.

Insomnia

Chronic inability to obtain the amount or quality of sleep needed to function adequately.

Components of the limbic system

Cingulate gyrus, hippocampus and parahippocampal gyrus, amygdala, olfactory bulbs and tracts. Fornix and other fiber tracts link limbic system structures together.

A flat EEG

Clinical evidence of death.

Arachnoid mater

Collagen and elastic fibers. Separated from dura mater by subdural space.

Motor components of reticular formation

Communicate with spinal cord via reticulospinal tracts, control skeletal muscles, regulate muscle tone, regulate visceral motor functions-heart, blood pressure, and respiration.

Projection fibers

Connect cerebral cortex with lower brain or spinal cord. Ex: corona radiata and corticospinal tracts.

Association fibers

Connect different parts of the same hemisphere, connect gyri or lobes.

Commissures

Connect gray matter of the two hemispheres. Largest is the corpus callosum.

Vermis

Connects the two hemispheres of the cerebellum.

Cerebrum functions (8)

Conscious thought processes: intelligence, reasoning, sensory perception, thought, memory, judgement, voluntary motor activities, and visual and auditory activities.

Diencephalon

Consists of 3 structures-thalamus, hypothalamus, and epithalamus. Forms the core of forebrain. Surrounded by cerebral hemispheres. Encloses third ventricle.

Substantia nigra

Contain melanin in their neurons (precursor of dopamine) • Relay inhibitory signals to thalamus & basal nuclei to prevent unwanted body movements • Produce dopamine, involved in Parkinson's.

Central nervous system CNS

Contains brain and spinal cord.

Brain stem

Contains gray matter nuclei in white matter. Controls automatic reflexes and functions for survival, connects higher and lower neural centers, and contains nuclei of 10 of the 12 cranial nerves.

Corpora quadrigemina

Contains oculomotor and trochlear nerves.

Motor areas

Control voluntary movement. Housed within frontal lobe: Primary (somatic) motor cortex, Premotor cortex, Broca's area, and Frontal eye field.

Left hemisphere

Controls language, math, science, and logic (90% people)-compose sentence, balance checkbook, memorize list. Most right-handed.

Dopamine

Controls movement, emotional response, ability to experience pleasure and pain.

Functions of the meninges: (4)

Cover and protect the CNS, protect blood vessels and enclose venous sinuses (drain blood away from brain), CSF, and form partitions in the skull.

Cerebral dominance

Designates the hemisphere that is dominant for language. In 90% of people, the left hemisphere controls language, math, and logic.

Alzheimer's disease

Diagnosed by-autopsy, PET scans now identify brain changes, loss in identifying common smells. Leading cause of dementia~age 65. Symptoms: slow, progressive loss of higher intellectual functions, loss of language abilities and memory. Changes in mood and behavior-attitiud, poor judgement, confusion, restlessness, repeated questions. Motor function remains intact.

Decussation of the pyramids

Tracts cross over to opposite side where medulla joins spinal cord Crossover point of the corticospinal tracts. Each cerebral hemisphere controls voluntary movements of muscles on the opposite side of the body.

Meningeal layer

True external covering of brain, continues into vertebral canal as spinal dura mater.

Lateralization of cortical function

Two hemispheres are symmetrical in structure but not equal in function.

Parkinson's disease

Usually in 50's-60's. Decreased dopamine production by substantia nigra-stiff posture, slow voluntary movements, resting tremor, shuffling gait, expressionless face, decreased balance. Dopamine isn't delivered to basal nuclei of cerebral white matter. Treatment: L-dopa or implanted electrodes (alleviate tremors).

Cranial nerve nuclei

VIII(vestibulocochlear), IX (glossopharyngeal), X (vagus), XI (accessory), and XII (hypoglossal)

Superior colliculi

Visual reflex centers-coordinate head and eye movements when follow an object, turn head and eyes in response to visual stimulus.

Frontal lobe functions

Voluntary motor functions, concentration, planning, verbal communication, decision making, and personality.

Additional centers of medulla oblongata regulate

Vomiting, hiccuping, swallowing, coughing, sneezing, and salivation.

Falx cerebelli

Divides left and right sides of cerebellum.

Lateralization

Division of labor between hemispheres.

Gyrus

Elevated ridge of tissue.

Limbic association area

Emotional impact, significant event, establish memories.

Cerebellar peduncles

Enable cerebellum to "fine-tune" skeletal muscle movements, interpret proprioceptive input, adjust posture, and maintain balance. 3 paired fiber tracts connect cerebellum to brain stem. 1. Superior peduncles-coonect cerebellum to midbrain. 2. Middle peduncles-connect pons to cerebellum. 3. Inferior peduncles-connect medulla to cerebellum.

3 spaces of the brain

Epidural, subdural, and subarachnoid space.

Corona radiata

Fibers radiate like a fan through cerebral white matter toward cortex.

3 primary vesicles (regions) in embryonic development

Forebrain, midbrain, and hindbrain.

Anterior association area (prefrontal cortex)

Frontal lobe, most complicated cortical region. Intellect, cognition, recall, and personality. Working memory for judgment, reasoning, persistence, and conscience.

Five lobes of the cerebrum

Frontal, parietal, temporal, occipital, and insult-small lobe deep to the lateral sulcus (memory, taste).

Parietal lobe functions

General sensory functions-touch, textures, and shapes.

Alzheimer's postmortem findings

Generalized cerebral atrophy, abnormal protein in brain and cerebral arterioles, and decreased Ach in cerebrum.

Lateral ventricles: what separates them?

In the cerebral hemispheres, separated by thin membrane-septum pellucidum.

Third ventricle: how does it communicate?

In the diencephalon, communicates through an opening-interventricular foramen.

Fourth ventricle

In the hindbrain, between pons and cerebellum, cerebral aqueduct-connects third ventricle to fourth ventricle, connects to subarachnoid space (fluid-filled space surrounding brain) via median aperture and paired lateral apertures. Merges with the central canal of the spinal cord.

Falx cerebri

In the longitudinal fissure between left and right cerebral hemispheres. Attaches to crista galli and internal occipital crest.

Long-term memory

LTM, has limitless capacity, remember many phone numbers by committing to LTM, ability to store and retrieve info declines with age.

Narcolepsy

Lapse without warning into REM sleep from the awake state.

Posterior association area

Large region in temporal, parietal, occipital lobes • Plays role in recognizing patterns and faces and localizing us and our surroundings in space • Involved in understanding written and spoken language (Wernicke's area)

Disorders of language

Lesions of Broca's area and lesions of Wernicke's area.

Drowsiness

Lethargy, proceeds to sleep.

Dural septa

Limit excessive movement of the brain within cranium.

Pituitary gland

Major control center of endocrine and autonomic nervous systems, maintains homeostasis.

Cerebral cortex: make up and functions (7)

Many convolutions, "conscious mind"-Awareness, sensory perception,voluntary motor initiation, communication, memory storage, understanding, judgment.

Declarative memory

Memories we can consciously recollect.

Insula lobe functions

Memory and interpretation of taste.

Nondeclarative memory

Memory of simple skills and conditioning (how to tie shoe laces).

Brain stem 3 regions

Midbrain, pons, and medulla oblongata.

BBB in hypothalamus

Missing, lack of BBB allows hypothalamus to sample chemical composition of the blood to maintain homeostasis.

BBB of vomiting center of brain stem

Missing, medulla oblongata, monitors blood for poisonous substances.

Limbic output

Most limbic system output is relayed through hypothalamus-Hypothalamus is main control center for: Visceral (autonomic) function, Emotional response. Reason for: Fear-increased heart rate,increased blood pressure, sweating... • Chronic emotional stress-visceral illnesses: High blood pressure, heartburn, stomach ulcers or Psychosomatic illnesses (emotion-induced illnesses).

Gray matter in CNS

Motor neuron cell bodies, interneuron cell bodies, dendrites, unmyelinated axons.

The 3 functional areas of the cerebral cortex

Motor, sensory, and association areas.

White matter in CNS

Myelinated axons.

Cerebral white matter

Myelinated fibers bundles into large tracts, responsible for communication. Commissures, association fibers, projection fibers.

Sleep disorders

Narcolepsy, insomnia, and sleep apnea.

Functional brain systems

Networks of neurons that work together for a common function, may be scattered.

Gray matter in the cerebral cortex

Neuron cell bodies, dendrites, glial cells (no fiber tracts), all neurons in the cerebral cortex are interneurons.

Midbrain nuclei

Nuclei that control cranial nerves III (oculomotor) and IV (trochlear).

Disorders of the hypothalamus

Obesity, body wasting-lose weight, sleep disturbances, dehydration, and emotional imbalances.

Olfactory bulbs and tracts

Odors can provoke emotions or be associated with memories-skunk smell repulses, perfume smell brings back memories of grandmother.

Hemiplegia

Paralysis on one side of boy or sensory and speech deficits.

Dural venous sinuses

Periosteal and meningeal separate. Large blood-filled spaces, drain blood from the brain and directs blood into the internal jugular veins.

Arachnoid villi

Permit CSF reabsorption into dural venous sinus blood.

Cingulate gyrus

Plays role in expressing emotions through gestures and receives input from other components.

Primary somatosensory cortex

Postcentral gyrus of parietal lobe. Receives sensory information from: skin (somatic receptors)-touch, pressure, pain, temperature and skeletal muscles, joints, tendons (proprioceptors)-sense of body position. Right hemisphere receives info from left side of body, capable of spatial discrimination. Face, lips, fingertips most sensitive.

Somatosensory association cortex

Posterior to primary somatosensory cortex in parietal lobe. Interprets sensations to determine size, shape, texture, and parts of objects being felt. Allows identification of known objects without seeing them ex: can distinguish keys, coins, marbles in pocket.

Primary (somatic) motor cortex: location and function

Precentral gyrus of frontal lobe, Allows conscious control of precise, skilled, voluntary movements of skeletal muscles. Face, tongue, and hands have most precise motor control. Large pyramidal cells with long axons, Motor innervation is contralateral.

Auditory areas

Primary auditory cortex and auditory association area.

Visual areas

Primary visual cortex and visual association area.

Remembering

Process of retrieving info from memory stores.

Occipital lobe functions

Processes incoming visual information, stores visual memories.

Choroid plexus: structure and function

Produces CSF, clusters of capillaries that hang from roof of each ventricles-surrounded by pia mater and ependymal cells joined by tight junctions.

Sensory areas

Provide conscious awareness of sensation. Primary somatosensory cortex, Somatosensory association cortex, Visual area, Auditory areas, Olfactory cortex, Gustatory cortex, Visceral sensory area, and Vestibular (equilibrium) cortex.

Multimodal association areas

Receive input from sensory areas, send outputs to multiple areas. Gives meaning to info received, store, compare, decide on action to take. • MAS = where sensations, thoughts, emotions become conscious

Amygdala

Recognizes and assesses danger and anger, elicits the fear response.

Electroencephalogram EEG

Records brain waves that represent this electrical activity. Used to diagnose-brain lesions/tumors, infarcts-loss of blood supply, infections/abscesses, sleep disorders, and epilepsy.

BBB in choroid plexuses

Reduced, capillaries of choroid plexuses must be porous and permeable to produce CSF, tight junctions between ependymal cells protect brain.

Cardiac center

Regulates heart rate and strength of contraction.

Inferior olivary nuclei

Relay sensory (proprioceptive) information from muscles and joints to cerebellum.

Disorders of basal nuclei

Result in too much or too little movement or jerky, involuntary movements (Huntington's disease, Parkinson's disease)

Short-term memory

STM, or working memory, temporary holding of info, limited to 7 or 8 pieces of info, ex: look up phone number, dial it, forget it.

Pineal gland

Secretes melatonin, helps regulate day-night cycles.

Transverse cerebral fissure

Separates cerebrum and cerebellum.

Central sulcus

Separates frontal lobe from parietal lobe-precetral gyrus of frontal lobe and post central gyrus of parietal lobe.

Parieto-occipital sulcus

Separates parietal lobe from occipital lobe.

Lateral sulcus

Separates temporal lobe from frontal and parietal lobes.

Longitudinal fissure

Separates the 2 cerebral hemispheres. Bundles of axons (tracts) allow communication between 2 hemispheres.

Coma

Severe injury to reticular activating system. A condition of deep stupor from which the patient cannot be roused by external stimuli.• Moderately deep level of unconsciousness from which a person can be aroused only by extreme repeated or painful stimuli • Hypoglycemia, diseases of liver or kidney, brain trauma, CVA, drugs

Sulcus

Shallow grooves between gyri.

What protects the brain? (4)

Skull/cranium, meninges, CSF, and BBB.

Infundibulum

Stalk that connects to the pituitary gland.

Limbic system

• "The emotional brain" • Processes and experiences emotions • Ring of cerebral and diencephalic structures that encircle the corpus callosum and thalamus. • "Limbus" = ring or border

Control of epilepsy

• Anticonvulsive drugs • Vagus nerve stimulators-Implanted under skin of the chest, Delivers pulses at predetermined intervals, Keeps electrical activity of brain from becoming chaotic

Hypothalamus

• Below thalamus, contains many nuclei ex: mammillary bodies.

Cerebellar processing for motor activity

• Cerebral cortex sends impulses to cerebellum-initiate voluntary muscle contractions. • Proprioceptors and visual and equilibrium pathways send info to cerebellum about body position and muscle tone. • Calculates best way to coordinate muscle contraction. • Cerebellum sends "blueprint" of coordinated movement to cerebral motor cortex=Cerebellum->superior peduncles ->midbrain -> thalamus -> cerebral cortex • Cerebral cortex initiates motor output via pyramidal (corticospinal) tracts to spinal cord

Consciousness

• Consciousness includes: Awareness of sensation, Voluntary initiation and control of movement, and Higher mental processing activities (memory,logic,judgment...)

Pons

• Contains sensory and motor fibers (tracts) that:connect higher brain centers and the spinal cord and relay impulses between motor cortex and cerebellum. • Origin of cranial nerves: V (trigeminal) VI (abducens) VII(facial) • Some nuclei are part of the reticular formation or help medulla oblongata maintain breathing.

Brain waves

• Generated by synaptic activity in the cortex-Not action potentials in white matter. • Each person's brain waves are unique Change with age, sensory stimuli, brain disease, chemical state of the body. Always present even during unconsciousness and coma.

Basal nuclei

• Gray matter, regulate motor output. • Start, stop, and monitor intensity of movements • Regulate slow/stereotyped movements, unnecessary movements, attention, and cognition

Alertness

• Highest state of consciousness and cortical activity • Responsive, aware of self, oriented to time/place • Sleep - natural, temporary state of unconsciousness from which a person can be aroused by normal stimulation

Cerebellar function

• If cerebellum detects disparity between intended and actual movement-It initiates appropriate corrective measures. • Cerebellar injury results in: loss of muscle tone and clumsy, unsure movements. • Alcohol intoxication impairs cerebellar function: Disturbance of gait - sway, stagger, fall, Loss of balance and posture - cannot balance on one foot, and Inability to detect proprioceptive info - cannot close eyes and touch nose.

Gustatory cortex

• In the insula-involved in taste Visceral sensory area-posterior to gustatory cortex, conscious perception of visceral sensations: upset stomach, full bladder Vestibular (Equilibrium) Cortex-posterior part of insula, conscious awareness of balance

Hypothalamus times the sleep cycle by

• Inhibiting the brainstem's RAS ->Cerebral cortex goes to sleep-(RAS is also involved in dreaming sleep) • Releasing "wake-up" chemicals (orexins) that stimulate RAS to arouse the cortex.

Auditory association area

• Located posterior to the primary auditory cortex • Permits perception/interpretation of sounds (speech, scream, music, thunder) • Stores memories of sounds • Song plays over and over in your head

Tonic-clonic (grand mal) seizures

• Loss of consciousness • Intense muscle contractions • Loss of bowel and bladder control • Biting of the tongue

Olfactory cortex

• Medial aspect of temporal lobes (in piriform lobes) • Only parts still devoted to smell are olfactory bulbs and tracts • Provides conscious awareness of odors

Brain structures involved in memory

• Medial temporal lobe • Hippocampus • Amygdala (emotional memory) • Basal nuclei • Substantia nigra of midbrain • Cerebellum (motor memory)

Stupor

• Moderately deep level of unconsciousness from which a person can be aroused only by extreme repeated or painful stimuli • Hypoglycemia, diseases of liver or kidney, brain trauma, CVA, drugs

Primary visual cortex

• Occipital lobe • Most of it is buried deep in the calcarine sulcus • Receives visual info from contralateral retina • Largest cortical sensory area • Damage can cause functional blindness

Epilepsy

• Occurs in 1% of the population • Flood of uncontrollable electrical discharges-No other messages can get through • Not associated with intellectual impairment • Causes - genetic, injuries, stroke, infections, fever, tumors, unknown • A victim of epilepsy may lose consciousness, fall stiffly, and have uncontrollable jerking

Basic regions of the cerebral hemispheres

• Outer cortex of gray matter • Internal white matter • Basal nuclei

Importance of sleep

• People deprived of REM sleep become moody, depressed, and exhibit personality disorders • REM sleep gives the brain an opportunity to analyze the day's events and work through problems • REM sleep may be a reverse learning process where meaningless information is purged from the brain by dreaming • Daily sleep requirements decline with age • Stage 4 sleep declines steadily-may disappear after age 60

Epithalamus

• Pineal gland-secretes melatonin, helps regulate day-night cycles(circadian rhythm). Antioxidant(molecule that neutralizes tissue-damaging free radicals-highly reactive molecules produced by body's metabolic process. Can disrupt structure of proteins, lipids, nucleic acids (DNA) may be involved in cancer development or aging process.

Cerebellum

• Receives input from cerebral motor cortex, brain stem nuclei, and sensory receptors • Provides precise timing and appropriate patterns of skeletal muscle (doesn't initiate skeletal muscle movement) contraction for-smooth, coordinated movements and agility-ex: driving, typing, playing piano • Stores memories of movement patterns • Playing scales on the piano

Respiratory center

• Regulates rate and depth of breathing (works with pons)

Vasomotor center

• Regulatesbloodpressurebychangingbloodvesseldiameter • Controls contraction and relaxation of smooth muscle

Sleep

• State of partial unconsciousness from which a person can be aroused by normal stimulation • Cortical activity is depressed • But brain stem functions continue • Respiration, heart rate, blood pressure • 2 major types of sleep (EEG patterns): (NREM) and (REM)

Primary auditory cortex

• Superior margin of the temporal lobes • Interprets information from inner ear as pitch, loudness, location

Visual association area

• Surrounds primary visual cortex in occipital lobe • Uses past visual experiences to interpret visual stimuli (color, form, and movement) • Gives ability to recognize a flower or a person's face and appreciate it • Damage-can see but don't comprehend what see

Sleep apnea

• Temporary cessation of breathing during sleep • Due to hypoxia (lack of oxygen)

Transient ischemic attacks TIAs

• Temporary episodes of reversible cerebral ischemia (5-50 minutes) • Temporary numbness, paralysis, or impaired speech