Autonomous Nervous System Flashcards
1. Answer the question: “What is the Autonomic Nervous System (ANS)?” (1.1.1) 2. Understand the basic anatomy of the Parasympathetic and Sympathetic divisions of the ANS and how they differ. (1.1.1) 3. Give a clinical overview of the functions of the ANS. (1.1.1) 4. Learn how to take a history and examine for ANS problems. (1.2.2, 1.2.3) 5. Understand the basic pharmacology of the ANS. (1.1.1)
What is the Nervous system
- brain
- spinal cord (central NS)
- nerves (peripheral nervous system)
function of the nerves
- transport sensory information to the brain
- transport motor information to muscles to produce the response
what is the autonomous nervous system?
the unconscious part of the nervous system
- it also receives sensory inputs, interprets them, produces motor outputs, but for all the day to day regulatory tasks that you don’t have to think about or be aware
What is a neuron
the main cell type of the central and peripheral nervous system
how is called the information that travels in neuron
elctrical signals called action potentials
how can neurones communicate across synapses
neurotransmitters
how can the speed of information conduction between neurons can be increased?
myelin sheath
2 divisions of the ANS
- sympathetic and parasympathetic systems
4 parts of the spinal chord
- thoracic
- lumbar
- sacral
- cervical
Entry/exit of axons to CNS for each ANS division - and their main function
Question you can ask in history to assess the ANS
Decreased sweating (fever, exercise, heat)
Dry mouth
Constipation / abdominal fullness
Postural dizziness (dizzy when standing up)
Bladder dysfunction (difficulty urinating or excessive urination)
Sexual dysfunction / inability to have an erection
what is an adrenergic receptor
receptors for catecholamine (nora and adrénaline)
name of the acetylcholine receptor
Muscarinic or nicotinic = cholinergic receptors
what kind of medication can promote or block specific autonomous function?
agonist = promote
antagonist = block
what is a non-selective medication
if it acts on all the receptors of a family (e.g. all beta receptors)
selective: only beta1 agonist
constriction of the bronchi (airways) are caused by..
and smooth muscle relaxaion of the airways?
cholinergic receptors (parasympathetic)
beta-adrenergic receptors (sympathetic)
Post-ganglionic receptors of the sympathetic system
adrenergic
post-ganglionic receptors of parasympathetic system
cholinergic
What structures have only sympathetic innervation?
Systemic arteries, sweat glands, and the bladder sphincter
The parasympathetic and sympathetic divisions usually have opposing functions. These are exceptions.
fight or flight response (sympathetic NS)
Sympathetic effects:
- increased rate and force of cardiac muscle
- blood flow is diverted to skeletal muscle
- bronchial smooth muscle is relaxed
- brings more oxygen to the muscles
- decreased blood flow through skin and visceral organs
- activity of the gastro‑intestinal tract is reduced and sphincters contracted
- pupils are dilated
- glycogenolysis and lipolysis mobilize energy stores
summarize the functions of the parasympathetic nervous system
SLUDD
- salivation,
- lacrimation,
- urination,
-digestion and
-defecation
which receptors are present on ganglia
nAChR = nicotinic acetylcholine receptors
where are the muscarinic ACh receptors?
mostly parasympathetic (cardia and smooth muscle, gland cells, nerve terminals)
when are norepinephrine or epinephrine hormones or neurotransmitters
Norepinephrine released from sympathetic nerve terminals acts as a neurotransmitter.
Epinephrine and norepinephrine, released from the adrenal glands into the blood, act as hormones.
where are the cholinergic synaptic junctions
all ANS ganglia, parasympathetic end organs and sympathetic (sweat glands only)
4 ways therapeutic drugs can increase or decrease the amount of acetylcholine that goes from persynaptic to post-synaptic
- act on presynaptic receptors (feedback control of acetycholine release)
- act on post-synaptic receptors (antagonist would bloc those receptors if we needed to decrease the amount of ACh)
- inhibit or sitmulate the action of acetylcholinesterase (that degrades de ACh in synapse)
- inhibit ACh release
Which are faster, nicotinic or muscarinic receptors?
nicotinic
what is a GPCR
G-protein coupled receptors
A typical GPCR gives rise to multiple intracellular signalling cascades. Generally, GPCRs signal in a slower fashion than ligand-gated ion channels such as nicotinic receptors. = muscarinic AChRs are GPCRs
one of the most important role of parasympathetic nervous system
slow the heart rate by acting on the cardiac pacemaker
In what kind of recepto calss do adrenoceptors are part?
muscarinic
many ways drug can act to stimulate or inibate the transmission of NE
- transmitter synthesis
- transmitter storage
- transmitter release
- pre or post synaptic receptors
- transmitter reuptake
- enzymatic inactivation
What happens if we inhibit transmitter reuptake of NE
excessive synaptic NE incrases bP and can cause stroke (cocaine)
how do you call receptors for epi and NE ?
adrenergic receptors and adrenoceptors
You can use drugs to stimulate postsynaptic adrenoceptors in two ways:
(1) Indirectly, by increasing transmitter release. Some nasal decongestants and amphetamine: we call these indirect agonists (see later).
(2) Agonist acting directly on receptors in order to mimic NE.
Is stimulating of blocking ganglionic nicotinic AChRs is therapeutically useful?
nop. better act on post ganglia receptors
How can muscarinic receptor activation cause vasodilation?
Muscarinic receptor activation increases release of nitric oxide (side note: nitric oxide = NO is also known as EDRF), which in turn activates intracellular guanylyl cyclase, leading to increases in intracellular cGMP levels, leading to smooth muscle relaxation and hence vasodilation.
