CNS
central nervous system
PNS
peripheral nervous system
central nervous system : includes
brain and spinal cord
peripheral nervous system : includes
all nerve fibers outside the brain and spinal cord
afferent messages
messages carried by the PNS to the CNS from sensory receptors
efferent messages
messages from the CNS out to muscles and glands, as well as autonomic messages that govern internal organs and blood vessels
cerebral cortex
-is the cerebrum's out layer of nerve cell bodies, which look like "gray matter" due to lack of myelin
-center for human's highest functions: thought, memory, reasoning, sensation, voluntary movement
myelin
the white insulation of the axon that increases the conduction velocity of nerve impulses
hemisphere
half of the cerebrum; each with 4 lobes
left hemisphere
dominant in 95% of people
frontal lobe
concerned with personality, behaviors, emotions, intellectual functions
frontal lobe : precentral gyrus
initiates voluntary movement
parietal lobe : postcentral gyrus
primary center for sensation
occipital lobe
primary visual receptor center
temporal lobe
behind the ear has the primary auditory reception center with functions of hearing, taste, smell
Wernicke's area
in temporary lobe: associated with language comprehension
-if damaged receptive aphasia results
receptive aphasia
the person hears sounds, but it has no meaning, like hearing a foreign language
Broca's area
in frontal lobe: mediates motor speech
-if damaged expressive aphasia results
expressive aphasia
the person cannot talk, person can understand language and knows what he wants to say, but can produce only garbled sound
basal ganglia
-buried deep within the two cerebral hemispheres
-help to initiate movement and control automatic associated movements e.g. swinging arms while walking
thalamus
main relay station where the sensory pathways of the spinal cord, cerebellum & brainstem form synapses
hypothalamus
major respiratory center, basic vital functions: temperature, appetite, sex drive, heart rate, BP control, sleep center, anterior and posterior pituitary gland regular, coordinator of ANS activity, stress response
cerebellum
-located under occipital lobe
-concerned with motor coordination of voluntary movements, equilibrium, muscle tone
brainstem
-central core of brain consisting of nerve fibers
-CN III through XII originate here
-three areas: midbrain, pons, medulla
midbrain
-anterior of brainstem
-merges into thalamus / hypothalamus
-contains many motor neurons & tracts
pons
-contains ascending sensory and descending motor tracts
-respiratory centers: pneumotaxic and apneustic
medulla
-continuation of spinal cord
-vital autonomic centers: respiration, heart, GI function
-nuclei for CN VIII through XII
spinal cord
mediates reflexes of posture control, urination, pain
spinothalamic tract
contains sensory fibers that transmit the sensations of pain, temperature, light touch
spinothalamic tract: posterior (dorsal) columns
conduct sensation of position, vibration, localized touch
proprioception
without looking you know where your body parts are in space in relation to each other
vibration
feeling vibrating objects
stereognosis
without looking, you can identify familiar objects by touch
pyramidial decussation
motor nerve fibers original in the motor cortex and travel to the brainstem, where they cross to the contralateral side and then pass down into the lateral column of the spinal cord
corticospinal tract
permits humans to have skilled and purposeful movements
extrapyramidal tracts
include all the motor nerve fibers originating in the motor cortex, basal ganglia, brainstem, spinal cord OUTSIDE the pyramidal tract
cerebellar systems
coordinates movement, equilibrium and posture, proprioception
-processes are subconscious
upper motor neurons
a complex of all the descending motor fibers that can influence the lower motor neurons e.g. corticospinal, corticobulbar, extrapyramidal tracts
-located in CNS
lower motor neurons
final common pathway" - funnels many neural signals here and privides the final direct contact with the muscles
-located in PNS
nerve
bundle of fibers OUTSIDE the CNS