PNS and ANS Flashcards
PNS:
Sensory inputs and motor outputs are categorized as what?
Sensory inputs are also classified as what?
Somatic or visceral
General or special
Structural components of the CNS:
- ______ _______ - pick up stimuli
- ______ ______ - axon terminals of motor neurons
- _____ - bundles of peripheral axons
- _____ - clusters of peripheral neuronal cell bodies
sensory neurons
motor endings
nerves
ganglia
Draw out the functional organization of the PNS chart.
Refer to notes.
How are sensory receptors classified functionally?
By location and by the type of stimulus detected.
What do peripheral sensory receptors detect?
Sensory stimuli
What are the different location based classifications of peripheral sensory recetpors?
Exteroceptors - stimuli outside the body
Interoceptors - stimuli from internal viscera
(aka visceroceptors)
proprioceptors - monitor degree of stretch
Where would exteroceptors be located? What do they detect?
Near or at body surface
Detect touch, pressure, pain, temperature most of special sense organs.
Where would interoceptors be located?
What do they detect?
internal viscera
detect temperature, taste, stretching of tissue (stomach)
Where would proprioceptors be located?
musculoskeletal organs
What are the different subdivisions of the stimulus detected classification of peripheral sensory nerves?
Mechanoreceptors - mechanical force - touch, pressure
Thermoreceptors - temp
Chemoreceptors - chemical composition of blood
Photoreceptors - light
Nociceptors - pain
If talking about sensory receptors that detects stretch in the stomach, what is it called?
Interoceptor mechanoreceptor
have to use both classifications
How are spinal nerves named?
How many pairs are there?
For point of issue from the spinal cord:
ex: cervical nerves (c1-C8)
31
What is a plexus?
Bundle of nerves
What are enlargements?
Nerve groups that supply the limbs (cervical and lumbar)
Spinal nerve arrangement:
- Spinal nerves arise from the spinal cord as a series of small ______
- These converge to form the ______ and ______ roots
- the roots join to form a mixed nerve called the _____ ______ _____
- this branches into the ______ ______ and ______ ______
rootlets
dorsal and ventral root
spinal nerve trunk
dorsal ramus and ventral ramus
What does the dorsal root contain?
The ventral root?
What do both the dorsal and ventral ramus contain?
Dorsal root - incoming sensory nerve fibres
Ventral root - outgoing motor nerve fibres
Ramus
- contains sensory and motor nerve fibres
Why is it a dorsal root ganglion? (i.e. why not ventral)
Unipolar is sensory - so cell bodies are in the PNS
Multipolar for motor - dendrites close to cell body, located in CNS
ANS controls ______ _____ functions
visceral motor
The ANS regulates ______ visceral functions (visceral motor division) such as what?
What does it innervate?
unsconscious
- heart rate, digestion, blood pressure, urination
Glands, smooth muscle and cardiac muscle
Give the chart from PNS onwards.
PNS
- Sensory
- somatic
- visceral
- Motor
- somatic
- visceral = ANS
- – Sympa
- – Parasympa
Comparison of motor systems:
Somatic vs. autonomic.
Somatic motor
- one motor neuron* from CNS to skeletal muscle
- conscious*
- axons well myelinated*, conduct impulses rapidly
Autonomic
- two motor neurons*
– preganglionic in brain or spinal cord and,
– postganglionic
(pre and post)
Conduction is slower due to:
- thinly myelinated or unmyelinated axons*
- motor neurons synapse in a ganglion (two synapses*, slows down impulse conduction)
In the sympathetic nervous system, what can the preganglionic fibres synapse on?
Postganglionic fibre or adrenal medulla
What are the two divisions of the ANS?
Mostly innervate same structures but opposite functions:
Sympathetic - fight or flight
Parasympathetic - rest and digest
Describe some responses to dangerous or exciting situations from the sympathetic system.
Widening of pupils, cold skin, sweating, inhibition of non-essential functions.
Which organs have only sympathetic stimulation?
sweat glands, adrenal medulla, arrector pili and blood vessels.
What are the housekeeping activities of the parasympathetic division?
SLUDD
- Salivation
- Lacrimation
- Urination
- Digestion
- Defecation
Which dominates, sympathetic or parasympathetic?
Para
Why do we get a lump in our throat when crying?
As a result of stress, trigger sympathetic, tries to circulate more air while triggering lacrimation
- as starting to cry, breathe faster
but, tears and mucus make us swallow more but the muscles are constricted here, causing a lump in our throat.
Parasympathetic will ____ the size of the pupil, sympathetic will _______ it.
decrease
increase
What are the anatomical differences between the sympathetic and parasympathetic.
1 - Arise from different regions of the CNS
- S - thoracolumbar
- P - craniosacral
2 - Length of postganglionic neurons
- S - long
- P - short
3 - Branching of axons
- S - highly branched (many organs)
- P - few branches (localized effect)
Role of the adrenal medulla:
- major organ of the _______ nervous system
- constitutes largest sympathetic ______
- secretes both _______ and _______
sympathetic
ganglia
norepineprhine and epineprhine
Describe the differences between innervation by the sympathetic and parasympathetic on the following structures:
- eye
- systemic blood vessels
- heart
- stomach, SI, LI
- ureter + bladder
Eye
- S - pupil dilates
- P - pupil constricted
Systemic blood vessels
- only sympathetic stimulation
Heart
- S - increase HR
- P - return HR to normal
Stomach, SI, LI
S - inhibit peristalsis, absorption and secretion
P - increased absorption, secretion and peristalsis
Ureter and bladder
S - inhibit detrusor muscle contraction + contraction of external urethral sphincter
P - contract detrusor, inhibit contraction of external urethral sphincter
What do general visceral sensory neurons monitor?
Stretch, temperature, chemical changes and irritation
Where are the cell bodies of visceral sensory neurons located?
Dorsal root ganglion
Where is the visceral sensory cortex located?
Insula
What sensory input does the insula receive?
General sensory input from thoracic and abdominal viscera
and gustation via thalamus
Which sense does not go to the insula?
Olfaction, sent to temporal lobe instead
Any incoming sensory information goes through what first?
What is the exception?
thalamus
olfaction
Visceral pain
- ___ pain results when visceral organs are cut
- _____ to localize
- visceral paint results from _____ irritation, _______ or spasms
- Visceral pain is often perceived to be of _____ origin
- this is called _______ pain
no
hard
chemical irritation, spasms, inflammation
somatic origin for visceral pain = referred pain
What is an example of referred pain?
Heart attack - feel in left limb or lower jaw
- either cuz sensory fibres and motor fibres enter/exit same place
or vasoconstriction of vessels supplying somatic region
Draw out the diagram with the different PNS divisions and cortexes of each.
Refer to notes
