CH. 14

(pt B) Match the cardiac components in the left column to the blanks near their functions on the right.

1. AV bundle : Electrical link(s) between atria and ventricles 2. Bundle branches: Convey(s) the impulse down the interventricular septum 3. AV node: Delay(s) occurs here while atria contract 4. Internodal pathways: Link(s) between the SA node and AV node 5. Purkinje fibers: Convey(s) the impulse throughout the ventricular walls 6. SA node: Set(s) the pace for the entire heart

(pt D) Which of these structures conduct(s) action potentials the slowest?

AV node

(pt F) Increased pressure in the ventricles would close what valve(s)?

AV valves only

14.79 ________ are blood vessels that carry blood away from the heart.

Arteries

(pt C) Describe the pressures in the atria and ventricles that would cause the opening of the AV valves.

Pressure in the atria would be greater than the pressure in the ventricles.

(video tutor: electrocardiogram) Based on the typical shapes of ECG waves, which wave does this 11th cardiac cycle most resemble?

QRS complex

(pt C) Which part of the intrinsic conduction system normally initiates the depolarizing impulse that causes a heartbeat?

SA node

(IP: electrical activity heart) Arrange these elements of the intrinsic conduction system in the order that a depolarizing impulse travels during a normal heartbeat.

SA node Intermodal pathways AV node AV bundle Bundle branches Purkinje fibers

14.32 Autorhythmic cells

are also called pacemakers because they set the rate of the heartbeat.

(pt B) An increase in sympathetic stimulation of the heart would increase stroke volume by increasing __________.

contractility

14.62 Drugs known as beta blockers will

decrease heart rate.

(pt E) How would a decrease in blood volume affect both stroke volume and cardiac output?

decreased stroke volume and no change in cardiac output

(pt D) What causes the aortic semilunar valve to close?

greater pressure in the aorta than in the left ventricle

14.2 Capillaries are

microscopic vessels in which blood exchanges material with the interstitial fluid.

14.15 The sac around the heart is the

pericardium.

14.16 The function of the pericardial fluid is to

reduce friction between the heart and the pericardium.

(IP: cardiac cycle) Isovolumetric relaxation and ventricular filling (two phases of the cardiac cycle) take place during __________.

ventricular diastole

(pt C) Match the term in the left column to the blanks near their definition on the right.

1. End systolic volume (ESV): the volume of blood in one ventricle after contraction 2. Stroke volume (SV): the volume of blood per heart beat pumped out by one ventricle 3. Venous return (VR): the volume of blood per minute flowing into one atrium 4. End diastolic volume (EDV): the volume of blood in one ventricle before contraction 5. Cardiac output (CO): the volume of blood per minute pumped out by one ventricle 6. Heart rate (HR): the number of heart beats per minute

(IP: cardiac output) Calculate the cardiac output if heart rate (HR) is 90 beats per minute, stroke volume (SV) is 110 ml/beatml/beat, end diastolic volume (EDV) is 140 mlml, and end systolic volume (ESV) is 30 mlml.

9.9 L/min

(pt D) These activities change heart rate by changing the balance of parasympathetic and sympathetic stimulation of the heart. Sort each of the activities according to whether it decreases or increases heart rate.

Decrease: Lying down, digesting a meal Increase: standing up, fright or anger, exercise

(pt E) Predict the changes in heart rate, stroke volume, and cardiac output for each of the following conditions by filling out the table below.

Increased symapthetic activity: Increase HR, SV, CO Increased preload: No change HR, Increase SV, CO Increased exercise: Increase HR, SV, CO Increased contractility: No change HR, Increase SV, CO.

14.R10 Your instructor announces a pop quiz. Which would you expect?

Increased sympathetic signaling and increased cardiac output

(pt B) Which of the following is correct about the filling of the ventricles?

Most blood flows passively into the ventricles through open AV valves.

14.80 ________ are blood vessels that return blood to the heart.

Veins

14. 60 Which will increase the heart rate?

both sympathetic stimulation and epinephrine stimulation of the SA node

(pt B) Would you call this QRS early, on time, or late compared to when other QRS complexes are formed?

early

(pt B) Which of the following would increase heart rate?

epinephrine and norepinephrine

(pt C) How would an increase in the sympathetic nervous system increase stroke volume?

increased contractility

(pt D) By what mechanism would an increase in venous return increase stroke volume?

increased end diastolic volume

(regulation cardiac output) Which of the following would increase cardiac output to the greatest extent?

increased heart rate and increased stroke volume

(pt E) Put the phases of the cardiac cycle in the correct order, starting after ventricular filling.

isovolumetric contraction, ventricular ejection, isovolumetric relaxation

14.35 The AV node is important because it

slows the transmission of the electrical impulses to the ventricles in order for the atria to finish contracting.

14.3 An artery is a vessel that

transports blood away from the heart.