Topic 6: Autonomic Nervous System Flashcards
What are the roles of the autonomic nervous system?
-inhibition/excitation of smooth muscle,cardiac muscle, glandular secretions
-maintain homeostasis by regulating, readjusting and coordinating visceral function
Physiological roles: regulate heart (BP, HR, contractibility), regulate secretory glands (saliva, sweat, bronchiole), regulate smooth muscles (bronchi, blood vessels, urogential system, GI tract)
What are three basic patterns of the ANS?
- SNS opposes PNS
- SNS compliments PNS
- innervation by one division of ANS
What is the structure of the sympathetic nervous system?
-short preganglionic neuron, long postganglionic neuron
What is the structure of the parasympathetic nervous system?
-long preganglionic neuron, short postganglionic neuron
What are the neurotransmitters of the ANS?
Preganglionic: acetylcholine
Postganglionic - sympathetic: noradrenaline or adrenaline
Postganglionic - parasympathetic: acetylcholine
What are the adrenergic receptors of the ANS?
a1: blood vessels, pupils, urinary bladder sphincter
a2: pancreas
b1: heart
b2: bronchioles of lungs
What are the cholinergic receptors?
- nicotinic: first synapse of both SNS and PNS
- muscarinic: effector organ
Sympathetic nervous system
- aka thoracolumbar division
- arises from lat horn of T1-L2
- fight or flight
Parasympathetic nervous system
- aka craniosacral
- arises from brainstem via CNs III, VII, IX, X and sacral regions of S2-S4
- rest and digest - conserves energy
PNS vs SNS - The eye: pupil, ciliary muscle, lacrimal glands
PNS: constricts pupil, contracts ciliary muscles (near vision), increases lacrimal secretion
SNS: dilates pupil, relaxes ciliary muscles (far vision), little effect on lacrimal glands
PNS vs SNS - The heart: SA node, atrial muscle, AV node, ventricular muscle
PNS: decreases rate of SA node, decreases force of atrial muscle, decreases conduction velocity of AV node, decreases ventricular muscle force
SNS: increases rate of SA node, increases force of atrial muscle, increases automaticity of AV node, increases force of ventricular muscle
PNS vs SNS - The GI tract: smooth muscles, salivary glands, gastric glands
PNS: increased motility of smooth muscles, increased secretion from gastric and salivary glands
SNS: decreased motility of smooth muscles, no effect of salivary or gastric glands
PNS vs SNS - The respiratory tract: smooth muscle, glands
PNS: bronchoconstriction of smooth muscle, increased secretion of glands
SNS: bronchodilation of smooth muscles, decreased secretion of glands
PNS vs SNS: The renal system: urination, blood vessesls, juxtaglomerular apparatus
PNS: increased urination, no effect on blood vessels or juxtaglomerular apparatus
SNS: decreased urination, vasoconstriction of blood vessels, renin secretion from juxtaglomerular apparatus
What is exercise-induced vasovagal syncope?
- fainting during exercise
- common in young people
- may be more sinister - refer
What occurs in the blood vessels, heart and kidneys when blood pressure is decreased?
Blood vessels: vasoconstriction
Heart: cardiac center increases heart rate and contractility therefore increasing cardiac output
Kidney: RAAS (renin-angiotensin-aldosterone system): renin secretion into blood –> angiotensinogen I conversion to angiotensin 2 by renin, converted into angiotensin 2 by ACE (angiotensin-converting enzyme) from lungs –> increases BP
How does angiotensin 2 increase BP?
- constrict blood vessels
2. stimulates adrenal cortex to release aldosterone which increases blood volume by increasing retention of H2O and Na+
What is anaphylaxis?
acute allergic reaction to an antigen to which the body has become hypersensitive
What are the symptoms of analphylaxis?
swelling, itching, hives, shortness of breath, cramps, nausea, vomiting, diarrhea
What is in an epipen?
adrenaline to activate sympathic nervous system and reverse symptoms
