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The brain Anatomy & Physiology

The brain

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The brain. Anatomy & Physiology. Brain: unremarkable appearance ~ 3 lbs 4 major regions. 1. Cerebral Hemisphere. right & left connected by large fiber tract: corpus callosum cover most of other 3 parts - PowerPoint PPT Presentation

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The brainAnatomy & Physiology

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Brain: unremarkable appearance ~ 3 lbs 4 major regions

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right & left connected by large fiber tract: corpus callosum

cover most of other 3 parts surface: elevated ridges = gyri separated by shallow grooves = sulci

Fissures deeper grooves separate regions of brain

1. Cerebral Hemisphere

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Gyri, Sulci, & a Fissure

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separates cerebral hemispheres other fissures separate brain into lobes

Longitudinal Fissure

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spaces in brain filled with CSF

connected to subarachnoid space (around brain & spinal cord) and central canal of spinal cord

Ventricles of the Brain

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parietal lobe posterior to central sulcus

receives impulses from sensory receptors (not special senses), interprets them◦pain recognition◦temperature◦light touch

Somatic Sensory Area

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Humunculus

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anterior to central sulcus in frontal lobe

major voluntary motor tract

Primary Motor Area

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Humunculus

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visual area

Occipital Lobe

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auditory & olfactory areas

Temporal Lobe

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Brocca’s Area: ability to speak◦@ base of precentral gyrus (usually only

on left side)◦injury inability to correctly vocalize

words

Frontal Lobe

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Frontal Lobotomy

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http://www.youtube.com/watch?v=_0aNILW6ILk

Frontal Lobotomy

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http://www.youtube.com/watch?v=c6kRP41ygrI

Phineas Gage

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anterior frontal lobe: higher intellectual reasoning

complex memories: frontal/ temporal lobe

all facets of speech: occipital/temporal/parietal lobes

Lobe Functions

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Gray Matter of the Brain

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gray matter in brain that is NOT in cerebral cortex

functions: help regulate voluntary motor activity by modifying instructions sent to skeletal muscle by primary motor cortex

Basal Nuclei

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Parkinson’s Huntington’s

Imbalances in Basal Nuclei

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2. Diencephalon

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sits atop brain stem enclosed by cerebral hemispheres major parts:

◦Thalamus◦Hypothalamus◦Limbic system◦Epithalamus

Diencephalon

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relay station for sensory impulses passing thru to sensory cortex

Thalamus

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ANS center role in:

◦temperature control◦water balance◦metabolism

Hypothalamus

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Limbic System: forms rim surrounding corpus callosum

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regulates autonomic & endocrine functions in response to emotional stimuli (“reacting” brain vs. cerebral cortex being “thinking” brain)◦set level of arousal◦motivation◦reinforcing behaviors◦rage, love, memory, empathy

Limbic System

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~size of thumb in diameter & ~ 3 inches long

3 parts:1. midbrain2. pons3. medulla oblongata

Brain Stem

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knots of capillaries w/in each ventricle

produce & secrete CSF (cerebral spinal fluid)

Choroid Plexus

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smallest, uppermost part of brain stem

cerebral aquaduct: tiny canal that runs thru midbrain connecting 3rd & 4th ventricles

contains reflex centers for vision, hearing

Midbrain

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Midbrain

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“bridge” rounded structure that protrudes below midbrain

contains apneustic (produces deep, prolonged inspirations) & pneumotatic center (inhibits inspiration)

Pons

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most inferior part of brain stem inferior border merges into spinal cord

centers: heart rate, BP, breathing, swallowing, vomiting

Medulla Oblongata

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large, cauliflower-like projects dorsally from under occipital lobe

2 hemispheres convoluted surface provides precise timing for skeletal muscle activity

controls balance & equilibrium

Cerebellum

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Head injuries are leading cause of accidental death in USA.

Concussion: dizziness, “see stars”, briefly lose consciousness; No permanent brain damage

Contusion: result of marked tissue damage. Cerebrum: may maintain consciousness Brainstem: coma

Cerebral Edema: swelling of brain due to inflammatory response to injury/ initially conscious neuro signs deteriorate (think edema or hemorrhage)

Traumatic Brain Injuries

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stroke 3rd leading cause of death in USA occur when blood circulation to brain is interrupted ◦vessel could be blocked (temporary or

permanent) or hemorrhaging

Cerebrovascular Accident(CVA)

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CVA characterized by:

◦abrupt onset of persisting neurological symptoms that arise from destruction of brain tissue

common causes:◦ intracerebral hemorrhage◦emboli◦atherosclerosis of cerebral arteries

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CVA Risk Factors1. hypertension2. hypercholesterolnemia3. heart disease4. narrowed carotid arteries5. hx of TIAs (transient ischemic attacks)6. diabetes7. smoking8. obesity9. excessive alcohol intake

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CVA Treatments Thrombolytic:

◦clot-dissolving drug: tissue plasminogen activator (t-PA) greatly improved prognosis for CVA

◦aspirin (makes plts slippery fewer clots)◦blood thinners

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Aphasia: from damage to left side cerebrum where language centers are

Motor Aphasia:◦damage to Broca’s area◦loss of ability to speak

Sensory Aphasia:◦loss of ability to understand written or

spoken word

Sequelae of CVA

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Transient Ischemic Attack “mini-stroke” due to temporary restriction of blood flow

symptoms last 5 – 50 minutes “red flags” that warn impending & more serious CVAs

TIA

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Alzheimer Disease (AD) most common type of dementia >10% population > age 65 4th leading cause of death in US characterized by progressive loss of

reasoning & ability to care for oneself cause of most cases unknown but…

◦genetic factors◦environmental or lifestyle factors◦normal aging process

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AD Pathology

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