A&P Chp. 12:The Central Nervous System Flashcards
Gray Matter
mostly unmyelinated processes and neuron cell bodies
White Matter
myelinated fiber tracts (axons)
Major Subdivisions of the Brain
Cerebral Hemispheres
Diencephalon: thalamus, hypothalamus, epithalamus
Brain Stem: midbrain, pons, medulla oblongata
Cerebellum “little brain”
Does size represent intelligence?
No. Size and number of neurons is irrelevant to intelligence. Complexity, or interactions of neurons and how they work together, dictate processing power.
Brain Ventricles
Made of epidymal cells
Fluid filled spaces in the brain
2 Lateral Ventricles: C-shaped chambers deep in the brain where most of the cerebrospinal fluid is made and connected to a 3rd ventricle
3rd ventricle: slit between the right and left halves of the thalamus; connects to 4th
4th ventricle: lies between brain stem and cerebellum; connects to central canal of spinal cord; CSF then exits and goes around entire brain and spinal cord
Gyrus
elevated ridges of brain
Precentral gyrus: controls skeletal muscle
Postcentral gyrus: locates where senses are coming from
Sulcus (sulci)
Shallow grooves of brain
Central Sulcus: separates frontal from parietal lobe; in between precentral and postcentral gyrus
Lateral Sulcus: separates from from temporal lobe; very deep but not a fissure
Parieto-occipital Sulcus: separates parietal from occipital lobe
Fissure(s)
Deep grooves that separate major regions
Longitudinal Fissure: Separates R and L hemispheres
Transverse Fissure: Separates cortex from cerebellum
Cerebral Lobes/5 Hemispheres
- Frontal
- Parietal
- Temporal
- Occipital
- Insula
Insula
Cerebral Lobe/Hemisphere hidden deep to portions of the temporal, parietal, and frontal lobes
Cerebral Cortex
Center of consciousness (knowledge, memories, everything)
Contains neuron cell bodies, dendrites, unmylinated axons, and glial cells (nuclei)
A rich capillary blood supply is near for high metabolic rate
Folds greatly increase surface area possibly meaning greater intelligence
Three types of activity areas: motor, sensory, association
Consciousness involves all areas of the brain
Primary Motor Cortex
Motor Area of the Cerebral Cortex
Precentral gyrus of frontal lobe
Primarily involved in voluntary motor control area devoted to skilled muscles (controls fingers, face, etc)
Controls skeletal muscles
Map of the Primary Motor Cortex
Motor Homunculus: shows the locations on the precentral gyrus which control the skeletal muscles of each body region.
More precise movements require more neurons which is why fingers and face take up more room than arms and legs which have broad movements.
Control is contralateral: affecting the opposite side
Premotor Cortex
Motor Area of the Cerebral Cortex Anterior to the primary motor cortex Involved in learned repetitious or patterned movements such as learning the piano Does not control skeletal muscles If damaged, you can learn again Trained brain to do these actions
Damage to Primary Motor Cortex
Contralateral: affecting opposite side of the body
Only voluntary control of skeletal muscle is lost and it can never be regained. It is impossible to relearn.
Reflexes remain because they are controlled by the spinal cord.
Damage to Premotor Cortex
Loss of programmed motor skills
Can be relearned if brain is trained again
Muslce strength and the ability to perform tasks remain (not automatic tasks)
Language Areas
Motor Area of the Cerebal Cortex
A motor center fro speech, controlling muscles of the tongue, throat, and lips
involved in planning some voluntary motor activities
Only found in one hemisphere….left?
Frontal Eye Field
Motor Area of the Cerebral Cortex
Controls voluntary movements of the eye
Primary Somatosensory Cortex
Sensory area of the cerebral cortex
Pencil Poking demonstration: can’t read braille with your shoulder becasue receptive field of neurons is bigger
Receives inputs directly from peripheral somatic sensory receptors
Localizes points of the body where sensations originate
Distribution of input areas for cutaneous sensations
Spaital Discrimination: identifies the areas of the body being stimulated
Somatosensory Association Area
Sensory Area of the Cerebral Cortex
Identify key in your hand by senses associated with what a key looks like.
Posterior to the primary somatosensory area
Integrates and analyzes information relative to size, texture for identification
Gets input from primary somatosensory association area
Visual Cortex
Sensory Area of the Cerebral Cortex
Medial surface of occipital lobe
Impulses from teh eyes are routed through the thalamus
Optical Illusions
Sensory fibers cross over to the opopsite side at the optic chiasm; matters what you are looking at and where it is located
Lateral geniculate nucleus (visual area) of the thalamus
Auditory Cortex
Sensory Area of the Cerebral Cortex
Superior part of the temporal lobe
Primary auditory cortex: pitch rhythm and loudness
Auditory association area: identifies/ perceives sounds using memories as references
Olfactory Cortex
Sensory Area of the Cerebral Cortex
Located above the orbits in the medial portion of the temporal lobes
Conscious awareness of different smells
Anterior Association Area
Multimodal Association Area
Prefrontal cortex
matures slowly (doesn’t finish til 20s) and influenced by environment
anterior frontal lobe
intellect, complex learning, recall and personality
Judgment and planning
Posterior Association Area
Multimodal Association Area
temporal, parietal, and occipital lobes
pattern recognition, localizing position
receives input from motor and other sensory association areas and interprets it
Ex: dropping an acid bottle, many sensory inputs together give the dominant feeling of danger
Frontal Lobotomy
Sever the frontal lobe from the rest of the brain
Stops all strong emotional reaction
“Shutter Island”
Limbic Association Area
Multimodal Association Area
Cingulate and parahippocampal gyri, and hippocampus
Provides emotional impact and sense of danger
Brain Lateralization
Both hemispheres participate in every activity, but one hemisphere is dominant for most activites
Left Hemisphere: language skills, math and logic
Right Hemisphere: creative skills, intuition, emotion, appreciateion of art and music, visual-spatial skills
Most right dominant are left handed and male
Most left dominant are right handed
Equal function may result in ambidexterity and/or dyslexia
Commissural Fibers
Myelinated fibers providing type of connection within the CNS
connects the R and L hemispheres
Ex: corpus callosum “body collosal”
Association Fibers
Myelinated fibers providing type of connection within the CNS
connect neurons within one hemisphere
Projection Fibers
Myelinated fibers providing type of connection within the CNS
connect cerebral hemispheres to other parts of the CNS
Ex: Internal capsule
Cerebral White Matter
Myelinated fibers providing the 3 types of connection within the CNS
Deep Cerebral Gray Matter (Basal Nuclei)
Diffuses masses of gray matter deep within the cerebral hemispheres
Involved in regulating slow, sustained motor movements such as arm swinging
Also inhibit unnecessary movements (stabalize and smooth primary movements)
This area is affected in Parkinson’s Disease causing tremors and slow, unsteady movements
Diencephalon
Brain region composed of thalamus, hypothalamus, and epithalamus
Surrounded by the cerebral hemispheres
Encloses the third ventricle