Autonomic nervous system Flashcards
What does the autonomic nervous system control
Involuntary activities
-Smooth muscle
-Cardiac muscle
-Various glands
What are the divisions of the ANS
Sympathetic
Parasympathetic
What is the function of the parasympathetic NS
REST AND DIGEST
Generally has discrete actions on single organs, in the body ‘core’:
-salivary gland; heart
CONSERVATIVE, anabolic effects:
-storing energy - digestion etc (cow in a field)
-slowing heart
Functions of the sympathetic NS
More widespread actions than PSNS, often affecting whole body:
-distribution of sympathetic nerves; circulating adrenaline
HOMEOSTASIS
-blood pressure thermoregulation
Fight, flight or fright:
-meeting demands of active muscle
-anxiety (dental treatment)
Structure of the parasympathetic NS
-Long pre-gang neuron
-Short post-gang neuron
-Ganglion near or in effector organ
Does the autonomic nervous system control breathing
NO the breathing muscles are skeletal and are controlled by somatic nerves
How to identify the sympathetic NS by structure
-Pre-gang and post-gang neurons are similar in length
-Synapse in the sympathetic chain or one of the collateral (or pre-vertebral) ganglia or in the adrenal medulla
What structures does the ANS affect within the body
SMOOTH MUSCLE
-blood vessels in various parts of the body
-bronchi, bronchioles
HEART
-gastrointestinal tract
-rate, force of contraction
GLANDS
-salivary glands
-gastro-intestinal glands
-sweat glands
METABOLISM
Transmitters associated with ANS
Acetylcholine (present in BOTH) pre and post neurons within PSNS
Noradrenaline (SNS) Post-ganglionic neurons
Which component of the nervous system is the ANS
Visceral efferent component
Where do sympathetic neurons arise from on the spinal chord
Thoracic and lumbar sections
Which sections of the spinal chord do the Parasympathetic neurons arise from
Cranial and sacral
Which class of receptors are present on both the post ganglionic neurons
Nicotinic / ionotropic receptors
Receptors receiving signal from sympathetic neurons are called what?
Adrenergic receptors
Where are muscarinic receptors found
On effector organs receiving signal from parasympathetic neurons
What type of receptors are muscarinic and adrenergic
Metabotropic
What does noradrenaline cause
-Contraction of smooth muscle (SM) in blood vessels (vaso-constriction)
-Relaxation of bronchial (SM)
(Bronchodilation)
What is Vaso-Constriction
The contraction of smooth muscle
What is Bronchodilation
Relaxation of bronchial smooth muscle
Why is adrenaline used in anaesthetic preparations
It acts as a vaso-constrictor to restrict blood flow in and out of the muscle to preserve the aesthetic allowing doses to be kept to a minimum and reduce the spread to other parts of the body
Where are nicotinic receptors found
Neuromuscular junctions
What does adrenaline bind to
Adrenergic receptors
What types of adrenergic receptors are there
2 Alpha
3 Beta (B-3 found on fat cells, not relevant)
Where are alpha-1 receptors found
On all smooth muscle, organs and glands
EXCEPT
Cardiac and some cells in kidneys
