PNS Flashcards
What is the name of the nervous system branch that controls voluntary movement
Somatic
What is the name of the nervous system that controls involuntary responses
Autonomic
Within the visceral nervous system, what is the difference between the sympathetic and parasympathetic branches
Symp-Fight or flight
-Mobilises bodily systems
-efferent nerves innervate the viscera (organs) and periphery (vasculature and sweat glands)
Parasymp
-Conserves energy
-Efferent nerves innervate the viscera (organs) only
How many pairs of cranial and spinal nerves are there?
12 CN
31SN
What is a dermatome and myotome
Dermatome: An area of skin supplied by a single spinal nerve
Myotome: Group of muscles innervated by a single spinal nerve
What is a nucleus
A collection of neurone cell bodies within the CNS
What is a ganglion
A collection of neurone cell bodies outside the CNS
What is a plexus
A network of interconnected nerves
Where do afferent (somatic and visceral) fibres have their cell bodies
Spinal ganglia
Where do visceral efferent nerves synapse
Peripheral ganglion
Give the overall outline for the PNS branches
Give the gross anatomy of a spinalnerve incl the 3 connective tissue layers
Three layers of connective tissues
External vascular layer - epineurium
Individual fascicles covered in perineurium
Individual axons covered in endoneurium
How are nerve fibres classified
Conduction velocity (A,B,C. A is fastest)
Axonal diameter (I-IV. I is largest)-Only sensory are measured
Give the 5 sensory neurone types(by type of detection)
Chemoreceptors
Thermoreceptors
Photoreceptors
Mechanoreceptors
Nocireceptors
Give the classification of types of receptors and what they detect
External
-Exteroreceptors
(Pain, temp, touch, pressure)
Internal
-Proprioeptors
(Movement, joint position)
-Enteroceptors
(Movement through gut, pH)
Give an example of where’ you’d find chemoreceptors
Detector molecules which bind to receptor e.g in olfactory bulb
Give an example of where’ you’d find photoreceptors
Detect light in retina
Give an example of where’ you’d find thermoreceptors
Detect temp in skin
Give an example of where’ you’d find mechanoreceptors
Mechanical opening of ion channels e.g skin receptors
What is the function of nociceptors
Detect tissue damage, interpreted as pain
What do muscle spindles detect?
Changes in muscle length
What do golgi tendon organs detect?
Changes in tension in tendons
What do joint receptors do?
Found in joint capsules-Detect start and end of movement
What is a neuromuscular junction
A unique synapse between a neurone and muscle fibre
The the reflex arc and the definition of a reflex(muscle)
- Stretching of muscle stimulates sensory receptor
- Sensory neurone activated
- Within integrating center, sensory neurone activates motor neurone
- Motor neurone activated
- Effector muscle contracts and relieves the stretching
An involuntary coordinated pattern of muscle contraction and relaxation elicited by peripheral stimuli
Outline the general structure of the autonomic nervous system
Has visceral afferent and efferent parts
Efferent can be sympathetic or parasympathetic
Releases Ach at pre-ganglionic neurons
Releases noradrenaline(sympathetic) or Ach(Parasympathetic) at post-ganglionic neurones
-Apart from vessels where Ach is always released
What does the autonomic nervous system sense and through what S/C nerves?
Relay sensory information from the core
Pain, fullness, blood pressure
T1-L2, S2-S4 and cranial nerves IX and X
Which spinal nerves does the autonomic nervous system motor segment innervate through?
Outflow to core and body wall
Controls pupils, sweat glands, salivary glands, heart muscle, airways
Parasympathetic(craniosacral): CN III, VII, IX, X and S2-S4
Sympathetic(thoracolumbar): T1-L2
Where is the sympathetic and parasympathetic outflow of the autonomic nervous system
Sympathetic: T1-L2
Parasympathetic: CN III,VII,IX,X; S2-S4
How does the sympathetic nervous system innervate the nerves in the region outside T1-L2?
Out of the spinal cord, through the ventral roots then white ramus communicans, up/down the paravertebral sympathetic trunks and through the gray ramus communicans into the peripheral tissue.
How is the heart innervated autonomically?
Sympathetic cardiac nerves
-Directly from T1-T4 into the cardiac plexus
or
-Travel through the white ramus communicans into the cervical spine through the sympathetic trunk then into the cardiac plexus
For the autonomic nervous system, where are the synapses for the sympathetic cardiac nerves?
Pre-aortic ganglia
Which CN innervates the lacrimal glands?
III
Which CN innervates pupillary constriction?
VII
Which CN innervates the parotid gland?
IX
Which CN innervates the salivary glands?
VII
Which classification of nerve fibre is unmyelinated?
IV C
How does the pathway of the sympathetic pathway differ from the parasympathetic pathway?
Sympathetic system affects the viscera and periphery whereas the parasympathetic system only affects the viscera
Where do somatic efferent/afferent nerves carry signals to/from
To: Skeletal muscles
From: Joints, Skeletal muscles, Skin
