Heart and cardiovascular system

Question 1

Location of heart

Answer 1

Thorax between the lungs in the inferior mediastinum

Question 2

Size of heart

Answer 2

size of fist

Question 3

Layers of the heart wall

Answer 3

epicardium, myocardium, endocardium

Question 4

surface of the heart

Answer 4

visceral pericardium

Question 5

Four valves of the heart

Answer 5

tricuspid, bicuspid, pulmonary, aortic

Question 6

Flow of blood through the heart

Answer 6

Deoxygenated blood enters into the heart through the superior and inferior vena cava.

Blood travels into the right atrium and flows through the tricuspid valve into the right ventricle.

Blood is pushed through the pulmonary valve into the

pulmonary artery and lungs when the right ventricle contracts and pick up oxygen.

Oxygenated blood is then carried back to the heart by the pulmonary veins into the left atrium through the mitral valve and into the left ventricle.

Contraction of the left ventricle forces the blood through the aortic valve, through the aorta, and out to the entire body.

Question 7

arteries that supply the myocardium

Answer 7

right and left coronary arteries

Question 8

veins that drain the myocardium

Answer 8

cardiac veins

Question 9

cardiac muscle tissue

Answer 9

specialized muscle tissue found only in the heart, striated, involuntary

Question 10

Pacemaker of the heart

Answer 10

SA node

Question 11

Normal EKG waves

Answer 11

-P Wave - caused by depolarization of atria
-QRS Complex - caused by depolarization of ventricles
-T Wave - caused by repolarization of ventricles

Question 12

Stroke Volume (SV)

Answer 12

The volume of blood pumped forward with each ventricular contraction.

Question 13

normal stroke volume

Answer 13

70 ml/beat

Question 14

Left side of heart

Answer 14

-Fully oxygenated blood arrives from lungs via pulmonary veins

-Blood sent to all organs of the body via aorta

Question 15

Right side of the heart

Answer 15

-Oxygen-poor blood arrives from inferior and superior venae cave

-Blood sent to lungs via pulmonary trunk

Question 16

Right and left atria

Answer 16

-Two superior chambers
-Receive blood returning to heart
-Auricles (seen on surface) enlarge chamber

Question 17

Right and left ventricles

Answer 17

-Two inferior chambers
-Pump blood into arteries

Question 18

Atrioventricular (AV) valves

Answer 18

• control blood flow between atria and ventricles
• Right AV valve has three cusps (tricuspid valve)
• Left AV valve has two cusps (mitral valve, formerly ‘bicuspid’)

Question 19

Semilunar valves

Answer 19

• control flow into great arteries; open and close because of blood flow and pressure
• Pulmonary semilunar valve: in opening between right ventricle and pulmonary trunk
• Aortic semilunar valve: in opening between left ventricle and aorta

Question 20

First heart sound (S1)

Answer 20

louder and longer “lubb,” occurs with closure of AV valves

Question 21

First Heart sound (S2)

Answer 21

softer and sharper “dupp,” occurs with closure of semilunar valves

Question 22

The entire cardiac cycle

Answer 22

Ventricular filling (during diastole)
Isovolumetric contraction (during systole)
Ventricular ejection (during systole)
Isovolumetric relaxation (during diastole)

Question 23

define cardiac output and explain its importance

Answer 23

Cardiac output is the amount of blood pumped by the heart per minute. It is determined by the stroke volume and heart rate,

Question 24

functional significance of the intercellular junctions between
cardiac muscle cells

Answer 24

Intercalated discs are small connections that join cardiac muscle cells (cardiomyocytes) to each other. Gap junctions are part of the intercalated discs. When one cardiac muscle cell is stimulated to contract, a gap junction transfers the stimulation to the next cardiac cell. This allows the muscle to contract in a coordinated way.

Question 25

describe the heart's pacemaker and internal electrical conduction system

Answer 25

- Your atria (top heart chambers), telling them to contract. - The atrioventricular (AV) node, delaying the signal until your atria are empty of blood. - The bundle of His (center bundle of nerve fibers), carrying the signal to the Purkinje fibers. - The Purkinje fibers to your ventricles (bottom heart chambers), causing them to contract.

Question 26

describe the nerve supply to the heart and explain its role

Answer 26

The heart is innervated by sympathetic and parasympathetic fibers from the autonomic branch of the peripheral nervous system. The network of nerves supplying the heart is called the cardiac plexus. It receives contributions from the right and left vagus nerves, as well as contributions from the sympathetic trunk.

Question 27

describe the unusual action potentials of cardiac muscle and relate them to the contractile behavior of the heart

Answer 27

action potential form SA nodes cause the atria to depolarize and contract forcing blood into the ventricles.

Question 28

describe in detail one complete cycle of heart contraction and relaxation.

Answer 28

1. Ventricular filling Ventricles expand and their pressure drops below that of the atria AV valves open and blood flows into the ventricles Filling occurs in three phases: A. Rapid ventricular filling: first one-third B. Diastasis: second one-third; slower filling P wave occurs at the end of diastasis C. Atrial systole: final one-third; atria contract End-diastolic volume (EDV) achieved in each ventricle (about 130 mL of blood) 2. Isovolumetric contraction a. Atria repolarize, relax and remain in diastole for rest of cardiac cycle b. Ventricles depolarize, causing QRS complex, and begin to contract c. AV valves close (as ventricular blood surges back against the cusps) Heart sound S1 occurs at the beginning of this phase "Isovolumetric" because although ventricles contract, they do not eject blood Pressures in aorta and pulmonary trunk are still greater than pressures in the ventricles Cardiocytes exert force, but with all four valves closed, the blood cannot go anywhere 3. Ventricular ejection a. Begins when ventricular pressure exceeds arterial pressure and semilunar valves open b. Pressure peaks in left ventricle at about 120 mm Hg and 25 mm Hg in the right First: rapid ejection: blood moves out of ventricles quickly Then: reduced ejection: slower flow with lower pressure Ejection lasts about 200 to 250 ms (T wave of ECG occurs late in this phase) Stroke volume (SV) is about 70 mL "Ejection fraction" is about 54% of EDV (130 mL) 60 mL remaining blood is end-systolic volume (ESV)

Question 29

relate the events of the cardiac cycle to the volume of blood entering and leaving the heart

Answer 29

As volume increases, pressure decreases. As pressure increases, volume decreases.

Question 30

define cardiac output and explain its importance

Answer 30

Cardiac Output- Amount ejected by each ventricle in 1 minute. Cardiac output = heart rate x stroke volume - CO=75 beats/min x 70mL/beat= 5250mL/min - Athletes 20L/min Cardiac Reserve—The difference between a person's maximum and resting CO - Disease diagnostic

Question 31

explain how the right and left ventricles achieve balanced output

Answer 31

. Right ventricular output exceeds left Ventricular output 2. Pressure backs up 3. Fluid accumulates in pulmonary tissue 1. Left ventricular output exceeds right ventricular output 2. Pressure backs up 3. Fluid accumulates in systemic tissue

Question 32

Identify the Four Valves of the Heart

Answer 32

Valves ensure one-way flow of blood through heart The Atrioventricular Valves * Controls blood flow between atria and ventricles * Right AV valve has three cusps (tricuspid valve) * Left AV valve has two cusps (mitral valve, formerly 'bicuspid') The Semilunar Valves (Pulmonary and Aortic Valve) * Controls flow into pulmonary artery and aorta; open and close because of blood flow and pressure