W4: Somatic Nervous System Overview Flashcards
What is the somatic nervous system?
Under voluntary division of the nervous system.
Branches of the nervous system
Central and peripheral
Afferent (PNS to CNS, sensory) and efferent (CNS to PNS, motor)
Peripheral divides into somatic and autonomic
Autonomic divides into sympathetic, parasympathetic and enteric
How many spinal nerve and cranial nerves are there?
31 spinal nerve pairs and 12 cranial nerve pairs
What information does the CNS integrate from PNS? (what does PNS include?)
Spinal and cranial nerve pair info
Ganglia
Nerve plexuses
Enteric nervous system
What are ganglia?
Collection of cell bodies that can be autonomic or sensory
What are nerve plexuses?
Nerve fibres branching and forming a network of nerves that will go to innervate other structures
Classifications of neurones
Multipolar = motor/efferent Bipolar = relay or special sense Pseudo-unipolar = sensory
What are glial cells?
Supporting cells
What are the different kinds of glial cells?
Ependymal cells Astrocytes Microglia Oligodendrocytes and Schwann cells Pic at pt 2 min7
What does myelination of axons do?
Increases speed of conduction and provides protection and structural support.
Difference between oligodendrocytes and Schwann cells
Oligodendrocytes can myelinated multiple axons and are found in the CNS whereas Schwann cells are found in the PNS and can only myelinate one.
Afferent division of the nervous system
Sensory portion of the nervous system - input
Stimuli from the PNS are transmitted to the CNS
Efferent division of the nervous system
Motor portion of the nervous system (output)
Stimuli from the brain initiate movement of skeletal muscle
What is grey matter
A collection of cell bodies
What is white matter
Where myelinated axons are running through
How are white and gray matter arranged in the spinal cord?
Grey is the H inside, white surrounds
Difference between dorsal and ventral
Dorsal is posterior and sensory/afferent
Ventral is anterior and motor/efferent
What is proprioception?
Awareness of our body position in 3D space
What cells is the nervous system made up of?
Neurones (10%) and glial cells (90%)
Microanatomy of the neurone
Cell body (1), dendrites (many), axon (usually 1), terminal bouton/synapses (many)
What are Ependymal cells?
Epithelial cells that line the ventricular system (where CSF is produced and surrounds the brain and spinal cord). Involved in making CSF.
What are astrocytes?
Contribute to the blood-brain barrier. Typical star shape. Binds neurones to capillaries in the meninges.
What are microglia?
Immune function
What do Oligodendrocytes and Schwann cells do?
Create myelin sheaths around neurones and provide structural support.
Do unmyelinated neurones have Schwann cells?
Yes their axons are still surrounded by Schwann cells but they have a more supportive role.
What are cell bodies in the periphery called?
Ganglia. E.g., dorsal root ganglion is a collection of cell bodies in the PNS
Why are spinal nerves mixed?
Because they carry sensory and motor neurones.
What does the afferent division detect?
Sensation taken from areas like skin or special sense organs.
Efferent division muscle types
Skeletal, cardiac, smooth
How does the efferent division conduct movement?
Via the NMJ. Conduct stimuli to skeletal muscle.
What is the functional unit of a nerve?
A neurone
Functional anatomy of the nerve (pt3 min11)
Numerous axon bundles (fascicles) surrounded by three protective layers.
Axons are surrounded by an endoneurium. Fascicles are surrounded by a perineurium. Epineurium (dense connective tissue) surrounds the whole nerve.
