HEART & CARDIOVASCULAR FUNCTION

12)During the T wave of the electrocardiogram, the ventricles are electrically ________ and functionally ________.

,relaxed?

13)Depolarization of the atria corresponds to the ECG's (Hint P-QRS-T)

P wave

35)List the important features of the ECG, and indicate what each represents.

P wave = atrial depolarization (contraction) QRS complex = ventricular depolarization and atrial repolarization (relaxation); masked in the complex T wave = ventricular repolarization (relaxation) P-R interval = period from the start of atrial depolarization to start of ventricular depolarization Q-T interval = time for the ventricles to undergo a single cycle

14)Abnormally slow depolarization of the ventricles would most change the shape of the ________ in an ECG tracing.

QRS complex

9)What is the sequence of conducting system of the heart? Hint SA node to .........

SA node -> AV node -> AV bundle -> purkinje fibers

10)Pacemaker cells isolated from the SA node generate action potentials at ________ beats per minute.

60-100

37)Compare bradycardia with tachycardia.

bradycardia = abnormally low heart beat tachycardia. = abnormally high heart beat

18)________ is to slow heart rate as________ is to fast heart rate.

bradycardia, tachycardia

8)In cardiac muscle, the fast depolarization phase of the action potential is the result of ________ membrane permeability to ________ ions.

increased, sodium

3)The left border of the heart is formed by the

left ventricle

4)The muscle layer of the heart is called ....

myocardium

26)What is coronary ischemia?

not having enough blood through the coronary arteries (caused by a blockage)

17)The heart is innervated by ________ nerves.

parasympathetic and sympathetic

27)Define cardiac cycle.

period between start of one heartbeat and the next

20)The volume of blood ejected from each ventricle during a contraction is called the

stroke volume

15)A faster-than-normal heart rate is called

tachycardia

23)Why is the left ventricle more muscular than the right ventricle?

the left ventricle supplies blood to the systemic circuit, which is larger than the pulmonary circuit which the right ventricle supplies. therefore, more muscle and pressure is needed.

30)Why does tetany not occur in cardiac muscle?

the much longer action potential prevents tetany

33)If the cells of the SA node failed to function, how would the heart rate be affected?

the signal would then begin at the AV node, reducing the heart rate to about 40-60bpm

36)Why is ventricular fibrillation fatal?

the ventricles quiver and therefore cannot pump any blood out of the heart, stopping circulation. responsible for cardiac arrest.

11)The T wave on an ECG tracing represents

ventricular repolarization

39)What effect would an increase in venous return have on the stroke volume?

when venous return increases, stroke volume increases

16)A slower-than-normal heart rate is called

bradycardia

31)List the three stages of an action potential in a cardiac muscle cell.

1. Rapid depolarization = voltage-gated fast sodium channels open; rapid Na+ influx 2. Plateau = membrane potential stays near 0mV slow calcium channels open = Ca2+ influx 3. Repolarization = slow calcium channels close slow potassium channels open; K+ rushes out restores resting potential

29)List the phases of the cardiac cycle.

1. atria contract together (atrial systole) pushing blood into the ventricles -- ventricles are relaxed (diastole) and filling 2. ventricles contract together (ventricular systole) -- atria are relaxed (diastole) and filling

22)From superficial to deep, name the layers of the heart wall.

1. pericardium= - outer fibrous pericardium - 2-layered serous pericardium --- parietal layer = areolar tissue and mesothelium ---- pericardial cavity = pericardial fluid --- serous layer = epicardium; mesothelium and areolar tissue 2. myocardium - cardiac muscle 3. endocardium - simple squamous epithelium & areolar tissue

34)Define electrocardiogram.

a recording/visualization of the heart's electrical activities from the body surface

2)The inferior point of the heart is called .................

apex

25)Compare arteriosclerosis with atherosclerosis.

arteriosclerosis = thickening of arterial walls atherosclerosis = formation of lipid deposits in arterial tunica media and damage to endothelium (common form of arteriosclerosis)

5)The earlike extension of the atrium is called .......

auricle

1)The superior portion of the heart where major blood vessels enter and exit is the.......

base

7)The ________ valve prevents backward flow into the left atrium.

bicuspid

32)Define autorhythmicity.

cardiac muscle's ability to contract at its own pace independent of neural or hormonal stimulation

38)Describe the sites and actions of the cardioinhibitory and cardioacceleratory centers.

cardioinhibitory center = controls parasympathetic neurons (supply to heart via vagus (X) nerve) slows heart rate cardioacceleratory center = controls sympathetic innervation (supplied via postganglionic fibers in cardiac nerves) increases heart rate

40)Define heart failure.

condition in which the heart cannot meet the demands of peripheral tissues, extremely low cardiac output

6)Where is bicuspid, or mitral, valve is located?

separates the left atrium and the left ventricle

28)Give the alternate terms for heart contraction and heart relaxation.

heart contraction = systole heart relaxation = diastole

21)Describe the heart's location in the body.

in the mediastinum (between the two pleural cavities)

24)What do semilunar valves prevent?

prevent the back flow of blood into the ventricles