ACTION POTENTIALS Chapter 11 Part 2 HONORS ANATOMY & PHYSIOLOGY.
The brain Honors Anatomy & Physiology for copying.
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Transcript of The brain Honors Anatomy & Physiology for copying.
the brain
Honors Anatomy & Physiologyfor copying
Brain: unremarkable appearance ~ 3 lbs
4 major regions
• 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
• separates cerebral hemispheres• other fissures separate brain into
lobes
Longitudinal Fissure
• spaces in brain filled with CSF
• connected to subarachnoid space (around brain & spinal cord) and central canal of spinal cord
Ventricles of the Brain
• parietal lobe posterior to central sulcus
• receives impulses from sensory receptors (not special senses), interprets them– pain recognition– temperature– light touch
Somatic Sensory Area
• anterior to central sulcus in frontal lobe
• major voluntary motor tract
Primary Motor Area
• visual area
Occipital Lobe
• auditory & olfactory areas
Temporal Lobe
• Brocca’s Area: ability to speak–@ base of precentral gyrus (usually only
on left side)– injury inability to correctly vocalize
words
Frontal Lobe
• anterior frontal lobe: higher intellectual reasoning
• complex memories: frontal/ temporal lobe
• all facets of speech: occipital/temporal/parietal lobes
Lobe Functions
Gray Matter of the Brain
• 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
2. Diencephalon
• sits atop brain stem• enclosed by cerebral hemispheres• major parts:– Thalamus– Hypothalamus– Limbic system– Epithalamus
Diencephalon
• relay station for sensory impulses passing thru to sensory cortex
Thalamus
• ANS center• role in:– temperature control– water balance–metabolism
Hypothalamus
Limbic System: forms rim surrounding corpus callosum
• 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
• ~size of thumb in diameter & ~ 3 inches long
• 3 parts:1. midbrain2. pons3. medulla oblongata
Brain Stem
• knots of capillaries w/in each ventricle
• produce & secrete CSF (cerebral spinal fluid)
Choroid Plexus
• 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
• “bridge”• rounded structure that protrudes
below midbrain• contains apneustic (produces deep,
prolonged inspirations) & pneumotatic center (inhibits inspiration)
Pons
• most inferior part of brain stem• inferior border merges into spinal
cord• centers: heart rate, BP, breathing,
swallowing, vomiting
Medulla Oblongata
• large, cauliflower-like • projects dorsally from under occipital
lobe • 2 hemispheres• convoluted surface• provides precise timing for skeletal
muscle activity• Controls balance & equilibrium
Cerebellum
• 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
• 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)
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
CVA Risk Factors
1. hypertension2. hypercholesterolnemia3. heart disease4. narrowed carotid arteries5. hx of TIAs (transient ischemic attacks)6. diabetes7. smoking8. obesity9. excessive alcohol intake
CVA Treatments
• Thrombolytic:– clot-dissolving drug: tissue plasminogen
activator (t-PA) greatly improved prognosis for CVA
– aspirin (makes plts slippery fewer clots)– blood thinners
• 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
• 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
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