Topic 6 Flashcards
Central nervous system is
smooth muscle, cardiac muscle and glands
Neuron can be distinguished by..
the type of neurotransmitter released
2 types of nt that are released
- cholinergic (ACh)
- adrenergic = norepinephrine (NE)
2 divisions of autonomic nervous system
- sympathetic nervous system
- parasympathetic nervous system
Sympathetic nervous system
prepares body for activity (ex: fight or flight response). its activated during exercise
To stop a chemical stimulation you need to..
remove the nt
To remove ACh what happens..
ACh broken own to AChE on post synaptic membrane (cell body/dendrites of postganglionic neuron or effector cell)
To remove NE what happens..
NE broken down by MAO in synaptic end bulb of neuron that released it
Parasympathetic nervous system
function is to rest and digest (housekeeping),
Most organs innervated by AND have both..
SNA and PSNS (usually have opposites actions`)
ANS regulates ..
internal processes continuously and automatically
Order of higher control ANS
cerebrum –> hypothalamus –> medulla oblongata –> ANS –> SNS or PSNS
3 types of movement
- reflexes
- voluntary
- rhythmic
Reflexes can be either..
- spinal
- postural
Spinal reflexes
least complex, require sensory input from muscle spindles
Postural reflexes
for balance, posture. require sensory input from proprioceptors, eyes, inner ear
Voluntary movement
most complex, no external stimuli required (act of will)
Rhythmic movement
walking, running, etc. combination of reflex and voluntary
6 levels of motor control (refer to chart)
- premotor cortex
- primary motor cortex
- brain stem nuclei
- spinal cord
- lower motor neurons
- sk. muscles
Level 1
planning what to move, sequence of muscle contractions, signals primary motor cortex and works with input from cerebellum
Level 2
signals directly to lower motor neurons (via corticospinal tract). fine skilled movements
Level 3
brain stem nuclei –> descending motor tracts–> lower motor neurons = indirect tracts. receive input from cortex, basal nuclei, cerebellum. involved in coordination of large muscle groups for maintenance of posture and locomotion
Level 4: Spinal cord
contains:
- cell bodies of lower motor neurons
- networks of neurons (central pattern generators) which set rhythmic, repeated movements (require cortical signals to begin or stop movement
Level 5: Cerebellum
role in planning and initiation movement (sends input into cortical areas). stores planned movement and compares actual to plan using sensory input. maintains balance controls eye movements, has a role in maintaining muscle tone. coordinates skilled voluntary muscle movements and timing of contractions involving more than 1 joint
Level 5: Basal nuclei
aid in planning movement, suppress unwanted motions, role in maintaining muscle tone
Corticospinal (direct) pathway
cortex to skeletal muscle
2 parts of the corticospinal direct pathway
- upper motor neurons
- lower motor neurons
Upper motor neurons of corticospinal pathway
cell bodies in primary motor cortex. axons down spinal cord
Lower motor neurons of corticospinal pathway
cell bodies in central horn of sp. cord. axons exit via spinal nerves
Destruction of upper motor neurons
reflex arcs still present
Destruction of upper motor neurons can cause ..
- spastic paralysis (increase muscle tone)
- exaggerated reflexes
Exaggerated reflexes example
plantar reflex- scratch sole of foot. if normal then plantar flexion of toes. if babinski sign then extend big toe (indicates damage to upper motor neurons (normal for babies though)
Destruction of lower motor neurons can cause …
- loss of reflex arc (no reflex)
- flaccid paralysis (decrease tone, marked muscle atrophy)
- ex: polio
Poliomyelitis
virus destroys cell bodies in ventral horn of sp cord
Language
areas in left cortex of most people (equivalent areas on right side produced emotional components of language)
Important brain regions of language
- cortex: for concepts
- wernicke’s area, broker’s area, basal nuclei: makeup the language implementation system and analyzes the incoming and produces outgoing word sounds and grammatical structures
- areas of the visual and auditory cortex
Signals pass from the language areas to..
premotor cortex to plan muscle contractions. primary motor cortex initiates planned contractions
What happens when theres damage to the wernicke’s
can’t understand spoken or written words but can speak but words are meaningless or mixed up
What happens when theres damage to the broca’s
understand words but difficult to speak of white sensibly
