Anatomy Chapter 12- The Central Nervous System Flashcards
Central Nervous System
Composed of Brain and Spinal Cord
Four regions of the brain
Cerebral Hemispheres
Diencephalon
Brain stem
Cerebellum
Gray matter
Contains dendrites, cell bodies, and axon terminals
All synapses are found in gray matter - motor control, sensory perception, memory, personality, etc.
White matter
Schwann cells and axons that sends the info along the length of the axon to the rest of the neuron
Form tracks
Passes messages between different areas of grat matter
Cerebral cortex
Outer layer of grat matter
Central canal
Found at the center of gray matter
Ventricles
Open cavities
Hollow chambers found in the brain that are filled with cerebropinal fluid and lined with ependymal cells
2 lateral ventricles
one in each cerebral hemisphere
3rd ventricle
found in diencephalon
4th ventricle
Found in hindbrain
Cerebral hemispheres general regions
Cerebral cortex (brain matter)
White matter (deeper)
Basal nuclei (deep to white matter)
Gyri
Ridges of cerebral hemispheres
Sulci
Shallow grooves that sit between gyri
Longitudinal fissure
Separates the left and right hemispheres
Transverse cerebral fissure
Separates the cerebral hemispheres from the cerebellum and brain stem
central sulcus
Separates frontal lobe and parietal lobe
Parieto-occupital sulcus
Separates occipiutal lobe from the parietal lobe
Lateral sulcus
Separates the temporal lobe from the frinal and parietal lobes
3 functional areas of the cortex
- Motor areas- vluntary movement
- Sensory areas- conscious awareness of sensations
- association areas- integrate diverse information
Contralateral
Relating to or denoting the side of the body opposite to that on which a particular structure or condition occurs
Motor Areas of the Cerebral cortex
- Primary Motor cortex
- Premotor cortex
- Broca’s Area
- Frontal Eye Field
Primary Motor Cortex
Allows for conscious control of skilled/precise voluntary movements
Pyramidal cells
Large neurons found in primary motor cortex
Corticospinal tracts
Axons of these neurons travel to the spinal cord through these
Promotor cortex fiunctions
- Helps plan movements
- Sensory feedback
Broca’s Area
Specialized motor speech area that directs muscles involved in speech production
Frontal Eye frield
Controls voluntary movement of the eyes
Sensory areas of the Cerebral cortex
1) Primary somatosensory cortex
2) Somatosensory association cortex
3) Visual areas (sight)
4) Auditory areas (hearing)
5) Vestibular cortex (balance/orientation)
6) Olfactory cortex (smell)
7) Gustatory cortex (taste)
8) Visceral sensory area (sensations of internal organs)
Primary Somatosensory cortex
receive information from the general sensory receptors in skin
Forms a sensory homunculus
Sensory Homunculus
The larger the body part, the more neurons are dedicated to that part of the body
Somatosensory Association Cortex
Integrates sensory input related to it through the primary somatosensory cortex
Produces understanding of what is being felt
Visual Areas
- Primary Visual Cortex
- Visual Association Are
Primary Visual Cortex
Largest cortical sensory area
Receives visual info that originates on the retina in the eye
Visual Association Area
Uses past visual experiences to interpret visual stimuli
Auditory Areas
- Primary auditory cortex
- Auditory association area
Primary auditory cortex
Interpretation of sound from inner ear as pitch, loudness and location
Auditory association area
Permits perception of sound stimulus and stores memories of sound for reference
Vestibular Cortex
Allows for conscious awareness of balance/orientation
Olfactory cortex
Conscious awareness of different odors
Gustatory cortex
Percweption of taste stimuli
Visceral Sensory area
Allows conscious perception of visceral sensations
Lateralization
Separation of tasks from the right and left hemispheres
Cerebral dominance
One hemisphere dominates a particular task
Left- usually Brocha (language, math, etc.)
Right- Usually Wernicke (Insightful, creative)
Fiber tracts
Connect the left and right side of the brain
Classification of cerebral white matter
- Association fibers
- Commissural fibers
- Projection fibers
Association fibers
Connect different areas of the same hemisphere
Commissural fibers
Connect corresponding areas of different hemispheres
Projection fibers
Allows sensory information to reach cortex motor output to leave cortex
Diencephalon
- Thalamus
- Hypothalamus
- Epithalamus
Thalamus
Relays sensory information into the cerebral cortex
Hypothalamus
Main visceral control center in body
Hypothalamus control functions
- Controls autonomic nervous system
- Initiates physical response to emotion
- Regulates body temperature
- Regulates food intake
- regulates water balance and thirst
- regulates sleep-wake cycle
- controls endocrine system function
Epithalamus
Contains the pineal gland that secretes melatonin that helps regulate the sleep-wake cycle
Brain stem
- Midbrain
- Pons
- Medulla Oblongata
Brain stem functions
- produces rigidly programmed, automatic behaviors
- Provides pathway for fiber tracts running from higher to lower brain centers
- Innervation of the head (10 of 12 cranial nerves associated)
Midbrain functions
- Regulates motor movement
- regulared hearing and vision
- alartness
- temperature control
Pons functions
- respiratory control
- bladder control
- swallowing
- most functions associated with attached cranial nerves
medulla oblongata functions
- cardiovascular center
- respiratory center
- regulate vomiting, swallowing, coughing, sneezing, etc.
cardiovascular center
regulates heart rate and blood pressure
higher contraction = more blood pressure
Respiratory center
controls respiratory rhythm, depth of breath
cerebellum
coordination and body position
1. thinking
2. language
3. emotion
Functional brain stems
Networks of neurons that span multiple regions of the brain that world together to accomplish one or more related tasks
Include…
1. limbic system
2. reticular formation
Limbic System
- Amygdaloid body
- Congulate gyrus
Amygdaloid body
Response to preceieve threats with fear or aggression
Cingulate gyrus
Expressing emotions through gestures, resoling mental conflicts during times of frustration
Psychosomatic illness
Illness with physical symptoms that results specifically from emotional causes
Prefrontal cortex
Responsible for decision making skills and plans out complex behaviors
Reticular activating system
Keep us awake, alert, and aware
RAS functions
- Sends continuous stream of impulses to the cerebral cortex
- Filters out repetitive, familiar, or weak signals
Broca’s Area
Production of spoken and written language, language processing and comprehension
Wernicke’s Area
Language comprehension, “speaking clearly”
Short term memory
Stores small amounts of information for shor periods of time
Long-term memory
Stores large amounts of information for longer periods of time
Transfer of short to long term memory
- Emotional state
- Rehearsal
- Association
- Automatic memory
Types of Memory
Declarative memory
Nondeclarative memory
declarative memory
Learning explicit information (factual information)
language, names, dates, etc.
Nondeclarative memory
Memories acquired through repetition (difficult to unlearn)
riding a bike, playing an instrument, etc.
Forms of protection for the brain
- Skull
- Meninges
- Cerebrospinal fluid
- Blood-brain barrier
Meninges
Membranes that surround and protect the brain
3 layers of connective tissue make up the meninges
Dura mater
Arachnoid mater
Pia mater
Dura Mater
Most external layer
Periosteal layer
Attaches to inner surface of skull bones
Meningeal layer
Forms the true external covering of the brain
Arachnoid mater
Deep to dura mater
Subarachnoid space
Contains spider web-like projections to secure arachnoid mater to underlying pia mater
Pia mater
Innermost meningeal layer
Highly vascularized
Cerebrospinal fluid
Liquid surrounding the brain and spinal cord
Choroid plexus
Produced by layer of cells in the ventricles
Blood-brain barrier Created by…
- Tight junctions between cells
- Astrocytes and pericytes
Function of blood-brain barrier
provides a constant environment for CNS tissue operation
Concussions
Alteration in brain functions following a physical blow to the head
Contusion
Permanent neurological damage resulting from bruising of the brain
Alzheimer’s Disease
Senile plaques found throughout the brains in between beurons and eventually cause neuron death
Alzheimer’s Symptoms
Memory loss, shortened attention span, disorientation
Langugae loss, dementia, changes in personality/mood
Parkinson’s Disease
Degeneration of dopamine-releasing cells in substantia nigra of mudbrain
Parkinson’s Disease symptoms
Consistent tremors, stuff facial expression, forward bent walking posture
Primary functions of the spinal cord
Conduction pathway
Major reflex center
Conduction pathway
Carries impulses to and from the brain
Major reflex center
Spinal reflexes are initiated and completed at the spinal cord level
Conus medullaris
Tapered, cone-shaped structure where the spinal cord ends
Filum terminale
Fibrous extensions that extend from conus medullaris to coccyx
Cervical and lumbar enlargements
Where nerves serving upper and lower limbs arise
Cauda equina
Collection of nerve roots at the end of the vertebral canal
Central canal
At center
Serves spinal cord with Cerebrospinal fluid
Gray matter
White matter
Dorsal horns
Projections of gray matter on the dorsal side of the spinal cord
Sensory input
Ventral horns
Projections of gray matter on the ventral side of the spinal cord
Motor output
Lateral horn
Projection of gray matter found only in thoracic and superior lumbar segments
Sympathetic neurons that serve visceral organs
Roots
Where axons enter or leave the spinal cord
Ventral roots
Where acons of ventral horm motor neurons (efferent) exit the spinal cord
Dorsal roots
Where axons of sensory receptors (afferent) enter the spinal cord
Dorsal root ganglia
Swelling of a portion of the dorsal root where cell bodies of sensory neurons are found
Spinal nerves
Dorsal and ventral roots fuse
Have both sensory and motor function
Paralysis
Loss of motor function
Inability or unwanted movements of certain parts of the body
Flaccid paralysis
Injurt to spinal cord or venteral roots prevents impulses form reaching skeletal muscle tissue
Spastic paralysis
Upper motor neurons of primary motor cortex are damaged
Paraplegia
Transaction between T1 and L1
Loss of lower limb functioning
Quadriplegia
Transection anywhere in the cervical region
Loss of function in all limbs
