The Autonomic Nervous System Flashcards
Efferent
Conducting/carrying outgoing signals
- carries signals from the brain/spinal cord to periphery
- motoneurone or autonomic neurone
Ganglion
- collection of neuronal cell bodies in the PNS
PRE-ganglion neurone - neurone immediately proximal to the ganglion
POST-ganglion neurone - neurone immediately distal to the ganglion
Effector
- target organ through which the nervous system exerts its action
The CNS
Encasement of the cranium and vertebral column (by bony structures)
Suspended in cerebrospinal fluid
Responsible for the sophisticated functions of the nervous system
Neurones in CNS known as pre-ganglionic
Axons are myelinated
White Rami communicates
The PNS
The nervous system outside of the CNS
Connects the CNS to target organs and sensory organs to the CNS
Neurones in PNS known as post-ganglionic
Stroma cause swellings known as ganglia
Axons are not myelinated
Grey Rami communicates
The somatic nervous system
Somatic efferents are under voluntary control
- are underdeveloped at birth so can be programmed by the environment
The autonomic nervous system
Becomes active with organogenesis and doesn’t stop during life
Balance between the sympathetic and parasympathetic systems
- establishes and maintains homeostasis
- autonomic tone varies between SNS and PNS dominance
- sweat glands only receive sympathetic drive
Overactivity of PNS = dilated blood vessels, shortage of substrate to brain, fainting
Overactivity of SNS = constriction of blood vessels - necrosis of body extremities
The sympathetic nervous system
fight or flight system
Expressed in stressful situations
- expenditure of energy
- diversion of blood to muscle and heart
- increased heart rate
- increased blood pressure
- reduced blood flow to skin and gastrointestinal tract
From the spinal cord only
- all 12 thoracic segments and the first 2 lumbar segments
- thoraco-lumbar division of ANS
- cholinergic
The parasympathetic nervous system
the rest and digest system
- reduced heart rate and force of heart contraction
- promotes digestion
- promotes emptying of bladder
- promotes sleep
From brain and spinal cord - cranial nerves (III, VII, IX, X)
- sacral spinal cord levels (S2, S3, S4)
- the Cranio-Sacral division
Post ganglionic (cholinergic and express nicotinic receptors)
Afferent
Conducts/carries incoming signals
- from periphery to CNS
- sensory neurones