LAB 7

cardiac cycle + output + cardiovascular reflexes

what do pacemakers do in regards to contractile cells?

they coordinate and initiate contractile cell activity

what precedes mechanical events?

electrical events

what is an electrical event in the heart?

electrocardiogram [ECG]

what are the mechanical events of the heart?

1. ventricular fillings

2. atrial systole

3. isovolumetric contraction (lub) - AV valves close

4. ventricular ejection

5. isovolumetric relaxation (dub) - SL valves close

if maximal ventricular filling is not coordinated w/ beginning of systole…

stroke volume and cardiac output decrease

what happens if valves do not function properly?

sterosis and regurgitation

what maintains homeostasis of blood pressure?

baroreceptor reflexes

what kind of sensory receptor are baroreceptors?

mechanoreceptors

where are baroreceptors located?

carotid sinus and aortic arch

what afferent nerves carry sensory information of BP to the brain?

vagus nerve (X) and glossopharangyeal nerve (IX)

what is the integrating center of the baroreceptor?

medulla oblongata

what are the two general efferents of the CVCC?

parasympathetic and sympathetic

the nerve that is the primary parasympathetic efferent…

vagus nerve

what is the primary target of the vagus nerve?

SA node

when is the parasympathetic efferent upregulated?

when BP is high.
Also HR is low.

the 3 cardiac nerves are all ____ efferents to the heart

sympathetic

where do nerves synapse on?

SA Node and AV Node of the heart

where do efferents of the same autonomic system synapse on?

blood vessels

when sympathetic efferent is upregulated…

blood pressure is low

what are the 3 effects of excitation of this efferent?

1. HR increases

2. Contractility increases

3. Vasoconstriction increases