Chapter 12 - Part 2 Flashcards
Brain Regions
Show specific motor and sensory functions that are located in discrete cortical areas
PET adn MRI scans
Discrete cortical areas that show specific motor and sensory functions
Domains
- Motor areas
- Sensory areas
- Association areas
3 Functional Regions of Cerebral Cortex
Control voluntary movement
Motor areas
Conscious awareness of sensation
Sensory areas
Integrate diverse information
Association areas
Two hemispheres are not entirely equal in ________
Function
Conscious behavior involves ______ in one way or another
Entire cortex
Each hemisphere is concerned with sensory and motor function of the _________ side of the body
Contralateral (opposite)
Located in precentral gyrus of frontal lobe; Contains large neurons that allow conscious control of precise, skilled, skeletal muscle movements
All muscles can be mapped to area
Damage = paralyzes muscles controlled by those areas
Primary (somatic) motor cortex
Located in postcentral gyrus of parietal lobe
Receives general sensory information from skin and receptors of skeletal muscle, joints, and tendons
Capable of spatial discrimination: identification of body region being stimulated
Primary somatosensory cortex
Receive inputs from multiple sensory spots and send outputs to multiple areas; Allows us to give meaning to information that we receive, store in memory, tie to previous experience, etc.
(Makes us who we are)
Divided into: anterior, posterior, and limbic areas
Damage to anterior = mental and personality disorders, including loss of judgement, attentiveness, inhibitions
Associtation areas
Concerned with conscious awareness of sensation
Occur in parietal, insular, occipital, and temporal lobes
Sensory areas
Division of labor between hemispheres (not identical)
Lateralization
Refers to hemisphere that is dominant for language
90% of humans have left dominance
Usually results in right-handedness
Cerebral dominance
Controls language, math, and logic
Left hemisphere
Visual-spacial skills, intuition, emotion, and artistic and musical skills
Right hemisphere
Hemispheres communicate _________
Instantaneously
Region of brain involved with speech production
Ex. Understanding words but cannot speak
Broca’s area
Region of brain involved with understanding spoken and written
Ex. Can speak, but words are nonsensical
Wernicke’s area
Responsible for communication between cerebral areas, and between cortex and lower CNS
Consists of myelinated fibers bundled into large tracts
Cerebral white matter
Horizontal running fibers that connect different parts of the same hemisphere
Association fibers
Horizontal fibers that connect gray matter of two hemispheres
Commissural fibers
Vertical fibers that connect hemispheres with lower brain or spinal cord
Projection fibers
Temporary alteration in brain function
Concussion
Permanent brain damage
Contusion
Pressure from blood may force brain stem through foramen, resulting in death
Subdural hemorrhage
Swelling of brain associated with traumatic head injury
Cerebral edema
Most common nervous system disorder and leading cause of death in NA
A.k.a Stroke
Occurs because of ischemia
Most common cause is blood clot blocking cerebral artery
Cerebrovascular accidents (CVAs)
Reduction in blood supply that impairs delivery of oxygen and nutrients
Ischemia
Paralysis on one side
Result of stroke
Hemiplegia
Progressive degenerative disease of brain resulting in dementia; Memory loss, short attention span, disorientation
Proteins appear to be misfolded and malfunction
Brain cells die –> Brain shrinks
Alzheimer’s Disease
Degeneration of dopamine-releasing neurons
Basal nuclei deprived of dopamine become overactive, resulting in tumors at rest
Cause is unknown, but theories include mitochondrial abnormalities or protein degradation pathways
Parkinson’s disease
Fatal hereditary disorder caused by accumulation of protein huntingtin in brain cells
Leads to degeneration of basal nuclei
Initial symptoms include wild, jerky, flapping movements
Fatal within 15 years
Huntington’s disease
Torrent of electrical discharges by groups of neurons, prevents any other messages from getting through
Can be caused by flashing lights
Epileptic seizure
Mild seizures of young children; expression goes blank for few seconds
Formerly: petit mal
Expression is “absent”
Absence seizures
Most severe; last few minutes
Victim loses consciousness, bones can be broken during intense convulsions
Tonic-clonic seizures
Identification of tumors, lesions, plaque, or areas of infarct
CT, MRI, PET scans
X rays used to pinpoint any stroke causing clots
Cerebral angiography
Evaluate blood flow through arteries feeding the brain
Used during pregnancy
Ultrasound
Hammer tapping agianst quad tendon
Abnormal responses may indicate intracranial hemorrhage, multiple sclerosis, or hydrocephalus
Knee jerk test
Composed of myelinated and unmyelinated nerve fibers that allow communication between different parts of the spinal cord and between the cord and brain
White matter
Bundles of nerve fibers in spinal cord
Tracts
Runs up to higher centers (sensory inputs)
Ascending tract
Runs from brain to cord or lower cord levels (motor outputs)
Descending tracts
Runs from one side to the other (commissural fibers)
Transverse tracts
_____ and _____ make up most of white matter
Ascending and descending tracts
Localized injury to spinal cord or its roots leads to functional losses
-Damage to dorsal roots or sensory tracts leads to sensory function loss or abnormal sensations (paresthesias)
Spinal cord injury
Caused by damage to ventral roots or ventral horn cells
Leads to motor function loss
Paralysis
Severe damage to ventral root or ventral horn cells
Impulses do not reach muscles, so they appear loose and “flaccid”
Flaccid paralysis
Damage to upper motor neurons of primary motor cortex
Spinal neurons remain intact; muscles are stimulated irregularly by reflex activity
Muscles remain healthy longer, but no voluntary control of muscles
Spastic paralysis
Transection between T1 and L1
Both lower limbs will be affected
Paraplegia
Transection in cervical region
All four limbs will be affected
Quadriplegia
Transient (temporary) period of functional loss in spinal cord
Spinal shock
Destruction of ventral horn motor neurons by poliovirus
Muscles atrophy
Death may occur from paralysis of respiratory muscles or cardiac arrest
Survivors = post polio syndrome = lethargy, muscle weakness
Poliomyelitis
Lou Gehrig’s disease
Destruction of ventral horn motor neurons and fibers of pyramidal tract
Symptoms: loss of ability to speak, swallow, and breathe
Death within 5 years
Caused by environmental factors and genetic mutations
Amyotrophic lateral sclerosis (ALS)
Cerebrum and parts of brain stem never develop
Anencephaly
Incomplete formation of vertebral arches
Most cases caused by lack of folic acid
Least severe = Spina bifida occulta
Most severe = Myelomeningocele
Spina bifida
