Lecture 12: Autonomics (Heart and Lungs) Flashcards
What parasympathetic innervation does the SA Node have?
What effects does it have on the heart?
- Vagus N. releases acetylcholine on muscarinic receptors on the SA Node
- Slows down depolarization = slows down HR
What type of sympathetic innervation does the SA and AV node have?
What effects does it have on the heart?
- T1 - T5 > sympathetic trunk > release Epi on Beta1 adrenergic receptors
- Faster depolarization = increase HR
What parasympathetic innervation does the AV Node have?
What effects does it have on the heart?
- Vagus > release Ach > muscarinic receptors
- Decrease depolarization rate and pacemaker potential which decreases conduction velocity between AV node and ventricles
What sympathetic innervation does the AV Node have?
What effects does it have on the heart?
- T1-T5 > sympathetic trunk > release epi on Beta1 receptors
- increase depolarization rate and pacemaker potential
Should the AV Node be the primary pacemaker of the heart?
What happens to ventricular rate during sympathetic and parasympathetic control?
-No
-Sympathetic: increases ventricular rate
Parasympathetic: decreases ventricular rate
What is the parasympathetic innervation of the atrial and ventricular myocytes? What are the effects?
Atrial: Vagus
Ventricles: unclear
-decrease atrial and ventricular contractility
What is the sympathetic innervation of the atrial and ventricular myocytes? What receptors accept them? What are the effects?
T1-T5 sympathetic trunk > B1 and B2 receptors
Increase calcium and myocyte contractility
What innervates cerebral vasculature? What is released and what happens?
Sympathetic > A1 adrenergic receptors > contracts vascular smooth muscle > vasoconstriction > decrease capillary blood flow to protect it
When does sympathetic control of cerebral vasculature happen?
High systemic BP that may damage brain capillaries (brain looks out for itself and sacrifices systemic BP to keep brain BP low)
What controls blood flow to the heart?
Metabolic needs over ANS. So metabolic needs can override ANS to increase/decrease blood flow to heart
What is the parasympathetic innervation to the coronary arteries? What are the effects?
Vagus N. (cholinergic)
Relaxes smooth muscle which vasodilates the artery and increases blood flow
What is the sympathetic innervation to the coronary arteries? What are the effects?
- T1-T5 sympathetics (A1 adrenergic)
- Contracts smooth muscle which vasoconstricts the arteries decreasing blood flow
Why is the vasoconstriction on the coronary arteries short lived?
Vasoconstriction will increase metabolism = increase metabolites = feedback on the sympathetic effect (vasodilation)
What is the major type of innervation to the cutaneous vasculature? What are the effects?
Sympathetic fibers from different places
Vasoconstriction
How are sweat glands innervated? What are the effects?
Sympathetic muscarinic
Relaxes vascular smooth muscle, vasodilates and contributes to sweat production
What is the major type of innervation to muscular vasculature? What are the effects?
Sympathetic (A1 and B2)
A1: vasoconstriction of arterioles
B2: vasodilation
What are the major innervation of the splanchnic vessels? What are the effects?
Sympathetic (T5-L2)
Contraction of vascular smooth muscle = vasoconstriction
From which ganglia does splanchnic vessel innervations arise from?
Celiac, superior mesenteric and inferior mesenteric
What are two ways that splanchnic vessels be vasodilated?
- Decrease sympathetic activity
2. Override by local control (metabolic needs)
What are the major innervations to the veins? What are the effects?
Sympathetic (A1,A2, B2)
A1: smooth muscle contraction, increase in venous return
A2 and B2: relaxation, decrease venous return
What is the arrangement of autonomic innervations in the pulmonary vasculature?
Decreases as you move closer to the alveoli
More sympathetic fibers than parasympathetic
How is the lung vasculature parasympathetically innervated? What are the effects?
Vagus N (cholinergic) NO production > vascular smooth muscle relaxation = vasodilation
How are the lung vasculature sympathetically innervated? What are the effects?
T1-T5 > A1 and B1
A1: vascular smooth muscle contraction = vasoconstriction of large vessels
B1: vascular smooth muscle relaxation = vasodilation of large vessels
What activates sympathetic innervation to pulmonary vasculature?
Cold air exposure and detecting distension of the large airways
How are the upper airways innervated parasympathetically? What are the effects?
Parasympathetic fibers from CN V and sphenopalatine ganglion
Vasodilation and increased mucus secretion
How are the upper airways innervated sympathetically? What are the effects?
Sympathetic fibers from CN VII and superior cervical ganglion (A1)
Vasoconstriction and decreased mucus secretion
What does intrinsic innervation mean?
Intrinsic nerve plexus that developed from the gut also innervate the trachea and large airways
How are lower airways parasympathetically innervated? What are the effects?
Vagus N.
Contraction of bronchial smooth muscle and increased mucus synthesis
How are lower airways sympathetically innervated? What are the effects?
T1-T5 (B2)
Relax bronchial smooth muscle and slightly increase mucus secretions
