ANATOMY AND PHYSIOLOGY - Autonomic Nervous System Flashcards
What is the function of the autonomic nervous system?
Regulation of the involuntary activity within the body
List the different involuntary function regulated by the autonomic nervous system
Cardiovascular response
Endocrine secretion
Gastrointestinal mobility and secretion
Reproductive control
Urogenital control
Which functional areas of the central nervous system regulate the autonomic nervous system within ALL organisms?
Brain stem
Spinal cord
Hypothalamus
Which additional functional area of the central nervous system regulates the activity of the autonomic nervous system in more advanced organisms?
Limbic cortex
What is the anatomical difference between the somatic and autonomic efferent neurones?
- Somatic nervous system requires only one efferent neurone to run from the central nervous system to the target organ
- Autonomic nervous system require two efferent neurones to run from the central nervous system to the target organ
What are the two autonomic efferent fibres present in the autonomic nervous system?
Pre-ganglionic fibres
Post-ganglionic fibres
What are ganglia?
Groups of neural cell bodies located in the peripheral nervous system
What are the two classifications of ganglia and what is the difference between the two?
Paravertebral ganglia: interconnected ganglia that are located close to the spinal cord
Prevertebral ganglia: individual ganglia located away from the spinal cord
Where in the central nervous system are the sympathetic cell bodies located?
Cranial-lumbar region of the spinal cord
Describe the anatomy of the pre- and post-ganglionic fibres of the sympathetic nervous system
- Short, finely myelinated pre-ganglionic fibres run from the cell bodies in the central nervous system to interconnected paravertebral ganglia
- Long non-myelinated post-ganglionic fibres run from the paravertebral ganglia to the target organs
How does the anatomy of the pre- and post-ganglionic fibres allow for a wide spread sympathetic response across the target organs?
Due to the long chain of interconnected paravertebral ganglia
List the cardiovascular responses induced by stimulation of the sympathetic nervous system
Positive chronotropic effect
Positive inotropic effect
Positive dromotropic effect
List the smooth muscle responses induced by the stimulation of the sympathetic nervous system
Mydriasis (pupil dilation)
Vasoconstriction and vasodilation
Decreased gastrointestinal motility
Bronchodilation
Bladder wall distension
Bladder neck constriction
Increased sphincter tone
List the endocrine responses induced by the stimulation of the sympathetic nervous system
Glycogenolysis
Gluconeogenesis
Where in the central nervous system are the parasympathetic cell bodies located?
Cranial-sacral region of the spinal cord
Describe the anatomy of the pre- and post-ganglionic fibres of the parasympathetic nervous system
- Long, finely myelinated pre-ganglionic fibres run from the cell bodies in the central nervous system to prevertebral ganglia located at the level of the target organs
- Short, non-myelinated post-ganglionic fibres run from the prevertebral ganglia to the target organs
Describe how the anatomy of the pre- and post-ganglionic fibres allow for a more controlled parasympathetic response across the target organs?
Due to the individual pre-vertebral ganglia close to the level of the target organs
List the cardiovascular responses induced by stimulation of the parasympathetic nervous system
Negative chrontropic effect
Negative inotropic effect
Negative dromotropic effect
List the smooth muscle responses induced by stimulation of the parasympathetic nervous system
Myosis (pupil constriction)
Vasodilation
Contraction of the bladder wall
Urethral peristalsis
Sphincter relaxation
Bronchoconstriction
Which area of the body have efferent neurones running from the parasympathetic nervous system but NOT the sympathetic nervous system?
The bronchi
What are cholinergic fibres?
Neurones that release acetylcholine
What are adrenergic fibres?
Neurones that release noradrenaline
What type of fibres are the pre- and post-ganglionic fibres of the parasympathetic nervous system?
Both the pre- and post-ganglionic fibres are cholinergic fibres
What type of fibres are the pre- and post-ganglionic fibres of the sympathetic nervous system?
The pre-ganglionic fibres are cholinergic fibres
The post-ganglionic fibres are adrenergic fibres
What are the two main types of cholinergic receptors?
- Nicotinic cholinergic receptors
- Muscarinic cholinergic receptors
Which neurotransmitter binds to cholinergic receptors?
Acetylcholine
What is the difference between nicotinic and muscarinic cholinergic receptors?
Nicotinic receptors are ligand gated ion channels whereas muscarinic receptors are G-protein coupled receptors
What are the two main types of adrenergic receptors?
Alpha adrenergic receptors
Beta adrenergic receptors
Which neurotransmitters bind to adrenergic receptors?
Noradrenaline and adrenaline
What are the three classifications of the nicotinic cholinergic receptors?
Nicotinic muscular receptors (NM)
Nicotinic ganglionic receptors (NG)
Nicotinic neuronal receptors (NN)
Where are nicotinic muscular receptors (NM) located within the body?
At the neuromuscular junction
Where are nicotinic ganglionic receptors (NG) located within the body?
At the ganglia
Where are nicotinic neuronal receptors (NN) located within the body?
In the central nervous system
What are the five classifications of muscarinic cholinergic receptors and where are they located within the body?
M1: neural tissue
M2: cardiac tissue
M3: glandular and smooth muscle tissue
M4: central nervous system
M5: central nervous system
What are the two classifications of alpha adrenergic receptors and where are they located within the body?
Alpha 1: vascular smooth muscle
Alpha 2: vascular smooth muscle and presynaptic tissue
What are the classifications of beta adrenergic receptors and where are they located within the body?
Beta 1: cardiac tissue
Beta 2: bronchi
Beta 3: ?
Beta 4: ?
Which division of the autonomic nervous system is the adrenal gland part of?
Sympathetic nervous system
What is the function of the chromaffin cells found in the adrenal medulla?
Chromaffin cells contain an enzyme which converts noradrenaline to adrenaline and secretes both into the bloodstream
What are the advantages of adrenaline and noradrenaline being released directly into the bloodstream by the adrenal gland?
- The adrenaline and noradrenaline will have a longer effect as these hormones have to travel through the bloodstream to the liver before being metabolised
- Travelling in the bloodstream allows adrenaline to make contact with all of the cells in the body allowing adrenaline to double metabolic rate
Which tissues are affected more by adrenaline and why?
Adrenaline has a higher affinity for beta adrenergic receptors so has more of an impact on cardiac tissue and bronchi
The autonomic nervous system exhibits tone. Why is this important to the function of the autonomic nervous system?
Continuous basal activity allows for fine control over the involuntary visceral functions
What is the function of co-transmitter molecules within the autonomic nervous system?
Co-transmitter molecules are molecules released with the main neurotransmitters involved in the autonomic nervous system to modify visceral organ response
What are the five main drug categories used to modify the function of the autonomic nervous system?
Adrenergic agonists
Adrenergic antagonists
Cholinergic agonists
Cholinergic antagonists
Anti-cholinesterase agents
What is the function enteric nervous system?
The system of neurones within the gastrointestinal tract which controls gastrointestinal movement, function and secretion
What are the two nerve plexuses within the enteric nervous system and where are they located?
Submucosal plexus: located between the epithelium and the circular muscle
Myenteric plexus: located between the circular and longitudinal muscle
What is the main function of the submucosal plexus?
Regulation of gastrointestinal absorption and secretion
What is the main function of the myenteric plexus?
Regulation of gastrointestinal peristalsis
Which type of sensory receptors provide information to the enteric plexuses?
Mechanoreceptors
Chemoreceptors
How does sympathetic nervous system stimulation effect the activity of the enteric nervous system?
Stimulation of the sympathetic nervous system inhibits enteric nervous system activity
How does parasympathetic nervous system stimulation effect the activity of the enteric nervous system?
Stimulation of the parasympathetic nervous system increases enteric nervous system activity
