The Anatomy of the Somatic Nervous System Flashcards
What are the two major divisions of the nervous system
The central nervous system (CNS) and the peripheral nervous system
What are the 2 directions of signalling in nerves
Afferent (towards the CNS away from PNS)
Efferent (away from CNS towards PNS)
What is the autonomic nervous system
The part of the nervous system that controls involuntary bodily processes
Why does only the efferent nervous system divide into somatic and autonomic systems
The effects carried by the efferent system can be voluntary or involuntary - somatic or autonomic
Describe the structure of the CNS (3 points)
- Made up of brain and spinal cord (encased in meninges)
- Both brain and spinal cord are in Cerebrospinal Fluid
- Most superficial layer is the cranium and Vertebral column
What is Meninges
A layer of connective tissue which acts as a membrane around the brain and spinal cord.
What are the 3 meninges
- Dura mater
- Dura Arachnoid
- Pia matter
What are the 2 functions of the PNS
- connects CNS to its target organs and tissues
- Connects sensory organs to CNS
What does the PNS include
- 31 spinal nerve pairs
- 12 cranial nerve pairs
- Ganglia
- Nerve plexuses
- Enteric nervous system
What are the percentages of neurones and glial cells that make up the nervous system
- Around 10% neurones
- Around 90% Glial cells
Describe the microanatomy of a neurone
- 1 cell body (perikaryon)
- Usually, 1 axon
- Many (axon) terminals
- Many dendrites
What are the 3 main types of neurons
Multipolar - Motor/Efferent
Bipolar - Relay or special sense
Pseudo-unipolar - Sensory
What are Glial cells (2 points)
- most common cell type in CNS
- create optimum microenvironment for neuronal activity
What are the 4 types of Glial cells
- Astrocytes
- Microglia
- Ependymal
- Oligodendrocytes
What are the functions of astrocytes (5 points)
- Contribute to blood brain barrier
- Structural and metabolic support
- May cause Gliomas
What is the structure of an astrocyte (2 points)
- star shaped
- most abundant type of glial cell
What are the functions of microglia
- Immune function and phagocytosis
- Maintaining brain homeostasis
- dysregulation can cause neurological disease
What are the functions of epydymal cells
What are the functions of oligodendrocytes
- Myelinate neurones in the CNS
- Provide metabolic support
What are the functions of Schwann cells
- Myelinate neurones in the PNS
- Provide metabolic support
What is myelin
A lipid sheath created by glial cells which surround the axon of a neurone
What does myelin do
- Increases speed of conduction
- Provides protection
- structural support
findit@bham.ac.uk What makes myelin
Oligodendrocytes in CNS
Schwann Cells in PNS
Describe the structure of axons on non-myelinated neurones
Axons are still surrounded by Schwann cells
What is the somatic nervous system
The part of the nervous system that is under voluntary control
What is proprioception
The awareness of our body in 3-dimensional space
What is the afferent division of the NS
Division that inputs stimuli from the PNS to the CNS
Where are the afferent neurones in the body found
The dorsal root of the spinal nerve
What is the efferent division of the NS
The output of the CNS to the PNS
Where are efferent neurones found in the body
The ventral root of the spinal
What processes are afferent neurones in charge of
Sensation
What processes are efferent neurones in charge of
Motor and Musko skeletal movement
What do you call an axon bundle
A Fascicle
What do many fascicles surrounded by 3 protective layers make
A nerve
What are the 3 protective layers that surround fascicles in a nerve (from closest to fascicles
- Endoneurium
- Perineurium
- Epineurium
