Basic Anatomy of the Somatic Nervous System Flashcards
what is the role of the NS?
important in integrating information coming from our external environment AND regulating internal processes
describe the different divisions of the NS
what is the NS split into?
central nervous system
peripheral nervous system
what is an afferent neurone?
send sensory impulses from receptors in the PNS to targets in CNS (PNS –> CNS)
what is an efferent neurone?
send impulses from the central nervous system to your limbs and organs (effectors) located in the PNS (CNS –> PNS)
way to remember: EFFErent goes to EFFEctors
why does only efferent system divide further and not afferent?
afferent system is simply just a sensory system (sensory neurones).
so they don’t divide into somatic and autonomic systems.
only the efferent system does as it only makes sense that effects are voluntary and involuntary.
what is the somatic and autonomic NS?
somatic- controls voluntary movement
autonomic- controls involuntary movement
what does the autonomic NS divide into?
sympathetic- fight or flight
parasympathetic- rest and digest
enteric- NS involved in regulating your gastrointestinal tract
what are the anatomical, directional and functional devisions of the NS?
anatomical- CNS and PNS
directional- afferent and efferent (gives you direction of impulse)
functional- somatic and autonomic (voluntary/ involuntay)
what does the CNS consist of?
- the brain and spinal cord
what layers of tissue cover the brain and spinal cord?
Meninges:
a layer of connective tissue which acts as a membrane around the brain and the spinal cord.
consists of:
- dura mater
- arachnoid matter
- pia matter.
what fluid is the brain and spinal cord suspended in?
Cerebrospinal Fluid - This is present in the subarachnoid space (between arachnoid and pia matter)
what is the superficial layer of the CNS?
Cranium (brain)
Vertebral Column (spinal cord)
what does the PNS do?
- nervous system outside the CNS
- connects CNS to target organs
- connects sensory to CNS
- so that the CNS can process information
what does the PNS consist of?
- 31 spinal nerve pairs
- 12 cranial nerve pairs
- Ganglia (autonomic/sensory) - bunches of neuronal cell bodies
- Nerve plexuses (Brachial/ lumbar/sacral) - networks of nerves that carry both afferent & efferent systems
- Enteric nervous system - regulating gastrointestinal tract
what cells does the NS mainly consist of?
- neurones (nerve cells) ~10%
- glial cells (supporting cells) ~90%
what is the structure of a neurone?
the nerve cell responsible for
conducting impulses
micro-anatomy of a neurone:
cell body (perikaryon) = 1
dendrites = many
axon = usually 1
terminal bouton/ synapses=
many
what is an axon hillock?
region where an action potential is generated.
produces ‘kink’ in neurones – visible in micrographs
what are the 3 types of neurones?
Multipolar = Motor (part of efferent NS)
Bipolar = Relay or special sense
Pseudo-unipolar = Sensory
what is the structure of a multipolar neurone?
- multiple dendrites
- one axon that divides into multiple synapses
what is the structure of a bipolar neurone?
- one dendritic process emerging to the cell body
- one axon that carries impulse from cell body to synapse
(hence bipolar) - mainly found in special senses ie. olfactory epithelium in nose, neuronal layers in retina
what is the structure of a pseudo-unipolar neurone?
- one process coming off cell body and immediately branching into dendrites and axons
- adv: info from dendrites can pass directly to the terminal synapse w/o having to go to cell body