2C Flashcards
What two things influence cardiac output?
HR and SV
What effect does the parasympathetic NS have on HR?
negative chronotropic effect
What effect does the sympathetic NS have on HR?
positive chronotropic effect
What parts of the heart have PNS innervation?
SA node, atria, and AV node
What is the nt of the PNS? What receptor deos this nt act on?
ACh, which acts on muscarinic receptors
What is a negative chonotropic effect?
Decrease HR by decreasing the rate of phase 4 depolarization.
Fewer action potentials
What parts of the heart have SNS innervation?
SA node, atria,, AV node, and the ventricles
What is the nt of the SNS? What receptor deos this nt act on?
Norepinephrine, which acts on Beta-1 receptors
What is a positive chonotropic effect?
Increases HR by increasing the rate of phase 4 depolarization
What hormones affect heart rate?
Epinephrine and Norepinephrine released by the adrenal medulla. Have similar effects as SNS. Important during exercise, stress, and excitement
What effect do Thyroid hormones have on HR?
Can elevate HR at rest
What effect do hyperkalemia and hypokalemia have on HR?
Both decrease HR by different mechanisms
T/F Age, gender, physical fitness and body temperature influence resting HR
True
