Traffic - week 4 Flashcards
CNS is..
A “wired” system
- specific pathways for transmission of signals between areas of body
- In general, coordinates rapid, precise responses - interacts with endocrine system (“wireless”)
afferent (sensory) division
carries information toward CNS
Organization of nervous system
central nervous system (CNS) 1. brain and spinal cord - peripheral nervous system (PNS) 1. nerve fibers carry information between CNS and rest of body
efferent (motor) division
carries information away from CNS to effector organs (muscles, glands). somatic nervous system. autonomic nervous system.
somatic nervous system (somas)
motor neurons supplying muscles
autonomic nervous system (fight)
(1) innervates smooth and cardiac muscle, glands (2) sympathetic division (“fight or flight”)
(3) parasympathetic division (“resting and digesting”)
3 Classes of neurons (AIE)
AIE
afferent, efferent, interneurons (most)
afferent - where
AP, near spinal so friends with synapses in spinal cord
- in afferent division of PNS
- peripheral end has a sensory receptor
a. generates APs in response to a stimulus 3. cell body near spinal cord - synapses with other neurons in spinal cord
efferent (mec)
mec
- in efferent division of PNS
- cell body in CNS
- terminates at a muscle or gland
interneurons
- in CNS, between afferent and efferent
neurons 2. interconnect with one another. protection nourishment of brain
glial cells (neuroglia) supporting cells of CNS
EMOA
astrocytes, oligodendrocytes, ependymal cells, microglia
astrocytes (HSSTCCK)
HSSCCK (holds neurons, scar, synapse formation, changes in blood, communication, K+)
a. hold neurons together
b. repair of injury and scar formation
c. induce changes in blood vessels (blood-brain barrier) and participate in transport across barrier d. take up and break down some nts (glutamate, GABA)
e. take up excess K+ in ECF
f. enhance synapse formation and modify function, physical and chemical influences
g. communicate with each other and neurons via
gap junctions, nts, and other chemicals
oligodendrocytes
a. forms myelin sheaths
ependymal cells
CNS, CSF, stem cells
a. line internal cavities of CNS (ventricles of brain,
central canal of spinal cord)
b. help form cerebrospinal fluid (CSF)
c. serve as stem cells in some areas of brain
microglia
a. defense cells, can do phagocytosis b. secrete nerve cell growth factor
blood-brain barrier
- capillaries in brain have tight junctions joining cells
a. only substances that can pass through cells can be exchanged 2. protects brain from harmful substances - keeps out circulating hormones that act like nts
meninges: connective tissue membranes
dura mater (outer), arachnoid mater (middle), pia mater (inner)
dura mater
a. forms dural sinuses and venous sinuses (blood and CSF pool, return to circulation)
arachnoid mater
a. subarachnoid space contains CSF
b. arachnoid villi reabsorb CSF (return to blood
in sinuses)
pia mater (inner)
a. well vascularized
b. important in forming CSF
bones offer…
physical protection
cranium (skull) - brain and vertebral column - spinal cord
cerebrum
gray DNG, white myeline
- cortex is outer layer of gray matter (neuron cell bodies and dendrites, glial cells) DNG
- underneath is white matter (tracts of myelinated fibers), which transmits signals between cortical areas, and to other CNS locations
- divided into functional areas (some degree of overlap) specialized for particular activities, but no area acts alone
2 hemispheres
- connected by corpus callosum
- most functional areas occur in both hemispheres (except language areas)
- some degree of specialization
a. left and right right - generally contralateral
paired lobes parts
POFT
- occipital, temporal, parietal, frontal
- functional areas often contained within a lobe
3 kinds of functional areas of cortex
SAM
- motor areas - control voluntary motor functions
- sensory areas - conscious awareness of sensation
- association areas - integrate diverse information
primary visual cortex (selected functional area)
a. receives visual information
b. surrounding higher-order visual cortex interprets
primary auditory cortex (selected functional area)
a. receives information on sound
b. surrounding higher-order auditory cortex interprets
somatosensory cortex
receives touch, localizes, homunculous
a. receives sensory input (somesthetic sensations from skin like touch, temp. and proprioception, etc.)
(1) localizes source of input, perceives intensity of stimulus, capable of spatial discrimination
(2) sensory homunculus - a particular region of the brain receives information from a certain part of the body
posterior parietal cortex
cleaning up dishes
a. integrates somatosensory and visual input
b. important in complex movement
primary motor cortex
a. voluntary control of skeletal muscle
(1) motor homunculus - neurons controlling a particular body part tend to be grouped together
supplementary motor area
a. helps prepare “programs” for complex patterns of movement
premotor cortex
a. plans movement based on body orientation, coordination of complex movements
b. interacts with posterior parietal cortex
language areas
broca’s area, wernicke’s area
broca’s area
(1) important in ability to speak - interacts with motor
areas for speech
Wernicke’s area
(1) important in language comprehension (written and
spoken) and patterns of speech
Broca’s and Wernicke’s usually
in left hemisphere only, right side has affective language areas, which express and comprehend emotion in speech
prefrontal association cortex
a. plans for voluntary activities
b. weighing consequences, making choices c. personality
d. complex learning, intellect (cognition), conscience
parietal-temporal-occipital association cortex
integrates information from those lobes
limbic association cortex
MEM
motivation, emotion, memory
cortex displays plasticity
many areas can change based on need, e.g.:
a. other areas may take over for damaged areas b. use of a particular body part can result in more
cortical space being devoted to it - areas constantly interact
Subcortical structures
BHT
basal nuclei (basal ganglia), thalamus, hypothalamus