Nervous System 4 - Motor Output Flashcards
Lec 11 & 12
What is the role of the Motor NS?
the communication of info from the CNS to the effectors for coordinated responses to changes in the internal or external enviro of the body. regulates involuntary processes through the autonomic NS, and controls voluntary mvmts through the somatic NS.
What are the 2 divisions of the motor nervous system?
Autonomic nervous system and the somatic nervous system.
What is the role of the autonomic motor NS?
transmits signals from the CNS (brain and SC) to autonomic effectors ie smooth mm, cardiac mm, and glands. the ANS regulates internal processes continuously and automatically.
How many neurons go from the CNS to the effectors in the ANS and what are they called.
2; the preganglionic neuron and the postganglionic neuron. how long they are and where they synapse at the ganglion depends on the autonomic NS division.
What are the 2 types of ANS neurons and the nt they release?
cholinergic - releases ACh acetylcholine. adrenergic - releases NE norepinephrine.
What are the two divisions of the ANS?
sympathetic nervous system and the parasympathetic nervous system.
What is the fxn of the Sympathetic NS?
prepares the body for activity. the fight or flight response. activated during exercise.
What are the types of ganglionic neurons in the SNS and what nts do they release? What is the exception?
preganglionic neuron is cholinergic so releases ACh. postganglionic neuron is adrenergic so releases NE.
exception is when the effector is sweat glands the postganglionic neuron is cholinergic (so both the pre and post neuron are cholinergic).
What is the neuronal pathway (motor) in the sympathetic nervous system?
signal starts in the CNS where the cell bodies are in the spinal cord. the axons exit vie the spinal nerves of T1-L2. signal goes down preganglionic neuron which synapses at the ganglion (group of cell bodies outside the CNS) and releases ACh. signal goes down postganglionic neuron to synapse at the effector and release NE. (so the pre neuron is cholinergic and the post neuron is adrenergic in the SNS)
How is chemical stimulation at a postsynaptic cell stopped (at either a neuron or effector)? How does it differ by nt?
the nt must be broken down or removed. Acetylcholine - is broken down by the enzyme acetylcholinesterase AChE. breakdown occurs on he postsynaptic membrane so the cell body/dendrites of the postsynaptic cell, so after ACh passes the synaptic cleft. Norepinephrine - is actively transported from the synaptic cleft back into the synaptic end bulb (so where it came from), and is then broken down by the enzyme monoamine oxidase MOA.
What is the fxn of the parasympathetic nervous system?
rest and digest. housekeeping.
What is the neuronal pathway (motor) in the parasympathetic nervous system?
signal starts in CNS where the cell bodies are in the brain stem in sacral SC. signal goes down preganglionic neuron which synapses at the ganglion and releases ACh. signal passes to postganglionic neuron which synapses at the effector and releases ACh. (so both the pre and post neuron are cholinergic an the PSNS)
Which systems do the organs controlled by the ANS receive input from?
most receive input from both the SNS and the PSNS. the effects of this stimulation is usu oppo from one another.
What are the effects of the SNS and the PSNS on the pupils of the eyes (iris mms)?
SNS; dilate PSNS; constrict
What are the effects of the SNS and the PSNS on the heart?
SNS; increase HR and force of contraction (pumping more bl) PSNS; decrease HR.
What are the effects of the SNS and the PSNS on the gastrointestinal tract?
SNS; decreases motility. PSNS; increase motility.
What are the effects of the SNS and the PSNS on the sweat glands?
SNS; increase secretion (cold sweat) PSNS; no innervation.
What are the effects of the SNS and the PSNS on the blood vessels (smooth mm)?
SNS; vasoconstriction (increases bp) PSNS; no innervation of bvs (except penis and clit)
What are the effects of the SNS and the PSNS on the digestive glands?
SNS; decrease secretion (except saliva) PSNS; increase secretion
What are the effects of the SNS and the PSNS on the genitals?
SNS; ejaculation PSNS; erection, lubrication
What is the higher control of the ANS and how does it work?
hypothalamus is ‘the boss’ sends signal down to medulla oblongata which goes down to the ANS and splits btwn the SNS and the PSNS. cerebrum which includes the limbic syst (emotion) sends cerebral input to the hypothal but is not needed for its ANS fxns bc there is no conscious control of the effectors, but emotions can cause autonomic effects.
What is the fxn of the somatic nervous system?
transmits signals from the CNS (brain and SC) to skel mms.
What is the neuronal pathway (motor) in the somatic NS?
signal starts at CNS in the brain. upper motor neuron sends signal to synapse at SC. signal then continues down a lower motor neuron which synapses at the effector.
What are the 3 types of mvmt possible in the somatic NS?
reflexes, voluntary, rhythmic.
What are the kinds of reflex mvmts in the somatic NS?
- spinal reflexes - least complex, require sensory input from sensory receptors like proprioceptors (mm spindles which measure stretch) and pain/press receptors. 2. postural reflexes - for balance and posture, require sensory input from proprioceptors (mm spindles), eyes, inner ear.
What is the voluntary mvmt type in the somatic NS?
most complex, no external stimuli required (act of will), so choosing to move ie picking up a glass of water.
What is the rhythmic mvmt type in the somatic NS?
walking running etc. combo of reflex and voluntary pathways. repetitive mvmts.
What is the pathway that neural signals take in the somatic NS ie within the lvls of motor control?
premotor cortex/supplementary area/association area –> primary motor cortex –> brain stem nuclei –> spinal cord –> lower motor neurons –> skel mms. will skip the brain stem nuclei if going via direct pathway.
What are the structures in the lvls of motor control in the somatic NS that relay signals to the CNS that help to plan, modify or control the mvmt thats happening?
cerebellum, sensory input, sensory cortex, basal nuclei.
What are the indirect and corticospinal/direct tracts in the somatic NS?
axons of the upper motor neurons that relay signals to the cell bodies of lower motor neurons in the SC.
Explain the lvls of motor control in the somatic NS diagram (as best you can without the diagram).
signal starts in 1. premotor cortex, supplementary area, association areas - plan mvmt. signal sent to 2. primary motor cortex which uses direct pathways to send the signal to the spinal cord or uses indirect pathways to send the signal to the brainstem nuclei. signal goes to 3. brain stem nuclei from indirect pathways which then sends signal to the spinal cord. direct tracts go right to 4. spinal cord, signals passed to lower motor neurons and then to the skeletal mms. while this is happening, sensory input goes to the cerebellum from the eyes ears and proprioceptors (where it sends input to the brain stem nuclei and premotor cortex), and the sensory cortex (which sends changes in plans to the basal nuclei which then sends signals to the premotor cortex), and does reflexes which go the the SC to go to LMNs and then skel mms.
What happens during lvl 1: planning?
do you want to move? what mvmt is needed? which mms need to contract? plans sequence of mm contractions, signals primary motor cortex, works wit input from the cerebellum
What happens during lvl 2?
primary motor cortex signals directly to lower motor neurons (via corticospinal/direct tract) for fine skilled mvmts.
What happens during lvl 3?
brain stem nuclei –> descending motor tracts –> lower motor neurons (this is the indirect tracts). receive input from the primary motor cortex, basal nuclei, cerebellum. involved in coordination of large mm groups for maintenance of posture, and locomotion.
What happens during lvl 4: spinal cord?
contains cell bodies of lower motor neurons. has a network of neurons called central pattern generators which set rhythmic repeated mvmt (walking, running). require cortical signals to begin or stop mvmt.
What does the cerebellum do in the lvls of motor control in the somatic NS?
planning and initiating mvmt by communicating with cortical areas. stores planned mvmt and compares to actual mvmts using sensory input from sensory receptors, corrects plan as needed by communicating to cortical areas. maintains balance, controls eye mvmts, has a role in maintaining mm tone (low lvl of contraction). coordinates skilled voluntary mm mvmts and timing of contractions involving more than one joint.
What does the basal nuclei do in the lvls of motor control in the somatic NS?
aid in planning mvmt, suppress unwanted mvmts by sending inhibitory signals, role in maintaining mm tone.
What does the corticospinal/direct pathway do in the lvl of motor control in the somatic NS?
signals from premotor cortex to skel mm. has upper motor neurons which have cell bodies in the primary motor cortex and axons in the SC. has lower motor neurons which have cell bodies in the ventral horn of the SC and axons that exit via the spinal nerves.
What happens with the destruction of upper motor neurons (list)?
its like theres a blockade in the neuronal pathway. reflex arcs are still present (sensory neurons can still send signals directly to lower motor neurons). this results in; 1. spastic paralysis 2. exaggerated reflexes.
What is spastic paralyis?
presence of reflex arcs increases mm tone.
What is exaggerated reflexes?
reflexes are stronger than usual bc there are no inhibitory signals from the upper motor neurons. so the plantar reflex would show the babinskis sign (extend big toe) bc theres damage.
What happens with the destruction of lower motor neurons (list)?
directly impacts skel mm. 1. loss of reflex arc where sensory neurons can no longer send signal to lower motor neurons so there is no reflex. 2. flaccid paralysis.
What is flaccid paralysis?
decreased mm tone, obvious mm atrophy (loss of mm tissue) bc no signals are being sent. ex. Polio - destroys cell bodies of lower motor neurons in ventral horn of SC.
How does language happen due to the NS?
involves complex interactions btwn nervous and muscular systems that allow speech production comprehension and expression.
What are the NB brain regions?
- cerebral cortex - for concepts and ideas 2. wernickes area - lang comprehension 3. brocas area - motor control of speech production and grammatical structure 4. basal nuclei - regulate speech production by communicating with the brocas area. 5. areas of visual and auditory cortex - process incoming language that is sen or heard. 2 3 and 4 are all a part of the lang implementation system.
What is the language implementation system?
analyzes the incoming and produces the outgoing word sounds and grammatical structures. consists of wernickes area, brocas area, basal nuclei.
What is the neural pathway of language?
signals pass from language areas to premotor cortex that plans mm contraction. premotor cortex then signals to primary motor cortex to initiate planned contractions to produce speech.
What happens if you have damage to the Wernicke’s area?
cant understand spoken or written words, can speak but words are meaningless and dont make any sense.
What happens of you have damage to the Broca’s area?
can understand words, but it is difficult to speak or write sensibly bc of loss of motor control of speech.
