Lecture 20: Organization Of Nervous System Flashcards
What are the 2 systems of the peripheral nervous system?
Somatic nervous system and autonomic nervous system
What are the 2 systems of the autonomic nervous system?
Sympathetic and parasympathetic
What are sensory / afferent fibres?
Fibres that carry impulses towards CNS
What are motor / efferent Fibres?
Fibres carrying Impulses away from the CNS
What is a ganglion?
Accumulation of neuron cell bodies outside the CNS
How do ganglion cells of sensory nerves look like?
Round with large ovoid nuclei and conspicuous nucleoli
How do autonomic ganglia look like?
Small, usually multipolar, giving off several dendritic processes and unmyelinated axons
What does the somatic nervous system do?
Cope with external environment
What does the autonomic nervous system do?
Control the internal environment
What kind of organ the somatic nervous system target?
Skeletal muscles
What 3 kinds of organs do autonomic nervous system target.?
Smooth muscle, cardiac muscle, glands
Where are the 2 places where autonomic preganglionic neurons cell bodies found in the CNS?
Sympathetic - lateral horn in T1-L2 cord segments
Parasympathetic - S2-S4 cord segments and brain stem
What are the 3 routes that sympathetic preganglionics can supply the skin via?
- Synapse at the level of entry
- Ascend the chain then synapse
- Descend the chain then synapse
How and what does the sympathetic preganglionics supply when it synapses at the level of entry?
Supplies dermatome sat the T1-L2 levels, so postganglionics get to their targets through the T1-L2 spinal nerves
How and what does the sympathetic preganglionics supply when it ascends the chain then synapses?
Typically supplies head and neck, post ganglionics get to their targets along the walls of blood vessels
How and what do the sympathetic preganglionics supply when it descends the chain then synapses?
Typically supplies lower limbs, get to their targets through the spinal nerves at level L3 and below
How do sympathetic nervous system distribute to abdominal viscera?
Can also traverse the chain then synapse in a pre-aortic ganglion and get to their targets along blood vessels
How do sensory Fibres travel?
Sensory Fibres also travel along sympathetics destined for the abdomen and relay pain from viscera back to the CNS
Where do parasympathetic preganglionic neurons usually synapse?
In ganglia that sit close to their target organs
What does the vagus nerve do?
Major source of parasympathetic preganglionic input to the thoracic and abdominal viscera
What are the 4 specialized parasympathetic ganglia in the head?
Ciliary, pterygopalatine, submandibular, otic
What does the ciliary ganglion do?
Receive parasympathetic preganglionics from the oculo motor nerve, distributes parasympathetic posrganglionics to the eye
What does the pterygopalatine ganglion do?
Receives parasympathetic preganglionics from facial nerve and distributes parasympathetic posrganglionics to the lacrimal gland
What does the submandibular ganglion do?
Receives parasympathetic preganglionics form the facial nerve and distributes parasympathetic posrganglionics to the submandibular and sublingual salivary glands
What does the otic ganglion do?
Receives parasympathetic preganglionics from the glossopharyngeal nerve and distributes parasympathetic posrganglionics to parotid gland
