Nervous system Flashcards
What is a ganglion?
Collection of nerve cell bodies
What are dendrites?
Extensions from the body that allow us to increase the surface area of a cell
What is the difference between a single axon an a named nerve?
Single axons only transmit a single fibre type (motor/sensory) but named nerves are a collection of axons so can transmit several fibre types
What are the 6 functions of a single nerve fibre(axon)?
1) Somatic sensory
2) Somatic motor
3) Special sensory
4) Visceral afferent
5) Sympathetic
6) Parasympathetic
What is the somatic sensory function?
It gives sensation and tells the spinal cord/brain about a pain somewhere on the body wall
What is the somatic Motor function?
It causes something to move/twitch and tell a skeletal muscle to contract
What is the special sensory function?
Tells the brain about a “special” sensation: sight, smell,taste,sound,balance
What is the visceral afferent function?
Tells the spinal cord/brain about a pain from an organ
What is sympathetic/ parasympathetic function?
Part of the autonomic nervous system and tells cardiac or smooth muscle to contract or a gland to secrete
What are the components of the central nervous system?
Brain and spinal cord
What makes up the peripheral nervous system?
- 12 pairs of cranial nerves mainly in contact with the brain e.g vagus nerves
- 31 pairs of spinal nerves that connect with the spinal cord and have named branches e.g phrenic
What nerve supplies the soma (body wall)?
Spinal nerves
What does the posterior ramus do?
Supplies the back (posterior part of the body wall) with sensation and motor supply
What does the anterior ramus do?
Supplies the rest of the body walls (anterolateral part of the body wall)
What is the function of the nervous system?
Allows us to sense our environment and to effect an appropriate response
What are the 2 categories of the nervous system?
- somatic- external environment
- autonomic nervous- internal environment
What does the somatic nervous system do and where are the neurones found?
Supplies the soma and responds to external environment.
-The neutrons are found in spinal nerve branches i.e intercostal/phrenic
What is the functions autonomic nervous?
Senses and responds to internal environment i.e heart rate and is involuntary as we dont need to think about it
What is ‘flight or flight’ controlled by?
Sympathetic nervous system
Describe the sympathetic supply to the soma?
- in ‘fight or flight’ , action potential are generated in autonomic centres in the brain
- the conducted via the spinal cord into T1-L2 spinal nerves
- sympathetic axons then enter all spinal and then all anterior and posterior ram I to be carried to the body wall
What thoracolumbar outflow?
Action potentials conducted into T1-L2 spinal nerves
How do sympathetic access head / neck and organs?
- on the arteries to ‘hitch a ride” to head and neck structures
- on arteries or cardiopulmonary splanchnic nerves
What do sympathetic connections (rami communications) connect?
Spinal nerves T1 to L2 and the paravertebral ganglia of the sympathetic trunk
What neurotransmitter lies in all paravertebral ganglia as part of the sympathetic system?
noradrenaline
What do pharmacological agents (drugs) do at synapses as part of the sympathetic system?
Target synapses to block the action of noradrenaline to e.g. modify a patients blood pressure etc
What is parasympathetic (craniosacral) “outflow” ?
Nerves containing parasympathetic axons travelling to only the organs - not the body wall
What nerves are parasympathetic carried in?
-cranial nerves III, VII,IX,X (mainly the vagus nerves) and sacral nerves
What neurotransmitter is found in parasympathetic ganglia system?
acetylcholine
What do pharmacological agents (drugs) do at synapses as part of the parasympathetic system?
Target the synapse to block the action of acetylcholine and e.g. dilate an asthmatic patients bronchioles etc
