Somatic nervous system Flashcards
What are the functions of the nervous system?
Perception
Control
Communication
Memory
What is the somatic nervous system?
Part of the nervous system that is under direct command of the human organism
Voluntary division of the NS
What are the main divisions of the somatic nervous system?
Central nervous system (CNS)
Peripheral nervous system (PNS)
What is the direction of signalling that takes place in the nervous systems?
Afferent system - to the brain (sensory)
Efferent system - from the brain (motor)
What makes up the CNS?
Brain and spinal cord
What are the various types of nervous tissue?
Neurones
Nerves - bundles of neurones
Macroglia
Microglia
What are the 3 main types of neurone?
Multipolar
Bipolar
(Pseudo) Unipolar
What is a multipolar neurone?
Large cell body
single axon
many dendrites
What is a bipolar neurone?
single dendrite
short single axon
generally sensory
What is a Pseudounipolar neurone?
Single dendrite from a common stem
short axon
Often sensory.
What protects the CNS?
Bone - Skull & Vertebral column
Meninges - Connective tissue acting as a membrane around the brian and spinal cord
CFS - fluid present in the subarachnoid space.
What are the layers of the Meninges?
Dura Matter
Arachnoid Matter
Pia Matter
What is Grey matter?
Groups of neuronal cell bodies
What is White matter?
Mainly myelinated axons
What does the spinal cord consist of?
Grey matter
White matter
Spinal nerves
What is the PNS?
Part of the NS outside of the CNS that connects the CNS to its target organs and tissues.
It also connects the sensory organs to the CNS
What does the PNS consist of?
Cranial Nerves - 12
Spinal Nerves - 31 pairs of nerves
Ganglia - 25 pairs of autonomic, 31 pairs of sensory
Nerve Plexuses - Brachial, Lumbar, Sacral
Enteric Nervous System (ENS)
What are the membranous envelops of the nerves?
From out to in:
Epineurium - Ensheathes the entire nerve
Perineurium - Ensheathes a nerve fascicle (collection of axons)
Endoneurium - Ensheathes a single cells axon.
What are Dermatomes?
Areas of skin supplied by a single spinal nerve
What are some features of Somatic Motorneurones?
Multipolar morphology
Cell bodies located in Ventral horn of spinal cord of cranial motor nuclei of the brain.
Largely Myelinated
What are some features of Somatic Sensory Neurones?
Pseudo-unipolar morphology
Varying myelination levels between subtypes
- Some myelinated
- Some unmyelinated
What are some properties of the somatic nervous system?
Exists in a bi-stable state (active/inactive)
Largely paralysed during REM sleep
Effector organ is skeletal muscle
What is the Redlich-Obersteiner’s Zone?
Formal boundary between the CNS and PNS located where cranial nerves join the substance of the brain stem or spinal cord.
What is different between the CNS and PNS?
They methods of myelination on axons.
CNS - Oligodendrocytes
PNS - Schwann Cells
What type of tumours are found in the PNS?
All tumours are Benign
What are malignant tumours a feature of in the CNS?
Features of Glia
What are some diseases of the CNS?
Raised intercranial pressure
MS
What are some diseases of the PNS?
Nerve compression syndrome
Demyelinating Polyneuropathies
