Anatomy & Physiology 2 Cv The Heart

Front 1

What size is the heart?

Back 1

~ The size of a fist

Front 2

Where is the heart located?

Back 2

• In the mediastinum between second rib and fifth intercostal space

• On the superior surface of diaphragm

• Two-thirds to the left of the midsternal line

• Anterior to the vertebral column, posterior to the sternum

Front 3

Where is the heart enclosed?

Back 3

Pericardium

Front 4

What does the superficial fibrous pericardium do?

Back 4

Protects, anchors, and prevents overfilling

Front 5

What are the layers of the pericardium?

Back 5

Parietal layer

visceral layer

Front 6

What does the parietal layer line?

Back 6

the internal surface of the fibrous peicardium

Front 7

Where does the visceral layer lie?

Back 7

on the external surface of the heart (epicardium)

Front 8

What is the parietal & visceral layer separated by?

Back 8

fluid filled pericardial cavity

Front 9

What does the pericardial cavity do?

Back 9

decreases friction

Front 10

What are the layers of the heart?

Back 10

Epicardium

Myocardium

Endocardium

Front 11

Myocardium

Back 11

• Spiral bundles of cardiac muscle cells

• Fibrous skeleton of the heart: crisscrossing, interlacing layer of connective tissue

• Anchors cardiac muscle fibers

• Supports great vessels and valves

• Limits spread of action potentials to specific paths

Front 12

Endocardium

Back 12

is continuous with endothelial lining of blood vessels

Front 13

Atria: The Receiving Chambers

Back 13

• Walls are ridged by pectinate muscles

Front 14

Vessels entering right atrium

Back 14

• Superior vena cava

• Inferior vena cava

• Coronary sinus

Front 15

Vessels entering left atrium

Back 15

• Right and left pulmonary veins

Front 16

Ventricles: The Discharging Chambers

Back 16

• Walls are ridged by trabeculae carneae

Front 17

What muscles project into the ventricular cavities?

Back 17

Papillary muscles

Front 18

Vessel leaving the right ventricle

Back 18

Pulmonary trunk

Front 19

Vessel leaving the left ventricle

Back 19

Aorta

Front 20

Pulmonary circuit

Back 20

R side of the heart

Vessels that carry blood to and from the lungs

Front 21

Systemic circuit

Back 21

L side of the heart

Vessels that carry the blood to and from all body tissues

Front 22

Pathway of Blood Through the Heart

Back 22

Right atrium - tricuspid valve - right ventricle - pulmonary semilunar valve - pulmonary trunk - pulmonary arteries - lungs

lungs- pulmonary veins - left atrium - bicuspid valve - left ventricle - aortic semilunar valve - aorta - systematic circulation

Front 23

Coronary Circulation

Back 23

The functional blood supply to the heart muscle itself

Front 24

Coronary Circulation: Arteries

Back 24

• Right and left coronary (in atrioventricular groove), marginal, circumflex, and anterior interventricular arteries

Front 25

Coronary Circulation: veins

Back 25

• Small cardiac, anterior cardiac, and great cardiac veins

Front 26

Angina pectoris

Back 26

• Thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium

• Cells are weakened

Front 27

Myocardial infarction

Back 27

• Prolonged coronary blockage

• Areas of cell death are repaired with noncontractile scar tissue

Front 28

Heart Valves

Back 28

Ensure unidirectional blood flow through the heart

Front 29

Atrioventricular (AV) valves

Back 29

• Prevent backflow into the atria when ventricles contract

• Tricuspid valve (right)

• Mitral valve (left)

Front 30

Chordae tendineae

Back 30

anchor AV valve cusps to papillary muscles

Front 31

Semilunar (SL) valves

Back 31

• Prevent backflow into the ventricles when ventricles relax

• Aortic semilunar valve

• Pulmonary semilunar valve

Front 32

Cardiac muscle cells

Back 32

striated, short, fat, branched, and interconnected

• Connective tissue matrix (endomysium) connects to the fibrous skeleton

• T tubules are wide but less numerous; SR is simpler than in skeletal muscle

• Numerous large mitochondria (25–35% of cell volume)

Front 33

Intercalated discs

Back 33

junctions between cells anchor cardiac cells

Front 34

Desmosomes

Back 34

prevent cells from separating during contraction

Front 35

Gap junctions

Back 35

allow ions to pass; electrically couple adjacent cells

Front 36

Heart muscle behaves as?

Back 36

a functional syncytium

Front 37

Depolarization

Back 37

is rhythmic and spontaneous

Front 38

What do gap junctions ensure?

Back 38

the heart contracts as a unit

Front 39

Intrinsic cardiac conduction system

Back 39

A network of noncontractile (autorhythmic) cells that initiate and distribute impulses to coordinate the depolarization and contraction of the heart

Front 40

Sinoatrial (SA) node (pacemaker)

Back 40

• Generates impulses about 75 times/minute (sinus rhythm)

• Depolarizes faster than any other part of the myocardium

Front 41

Atrioventricular (AV) node

Back 41

• Smaller diameter fibers; fewer gap junctions

• Delays impulses approximately 0.1 second

• Depolarizes 50 times per minute in absence of SA node input

Front 42

The bundle branches

Back 42

conduct the impulses through the interventricular septum

Front 43

The Purkinje fibers

Back 43

depolarize the contractile cells of both ventricles

Front 44

Atrioventricular (AV) bundle (bundle of His)

Back 44

Only electrical connection between the atria and ventricles

Front 45

Right and left bundle branches

Back 45

Two pathways in the interventricular septum that carry the impulses toward the apex of the heart

Front 46

Purkinje fibers

Back 46

• Complete the pathway into the apex and ventricular walls

• AV bundle and Purkinje fibers depolarize only 30 times per minute in absence of AV node input

Front 47

Heartbeat is modified by the?

Back 47

ANS

Front 48

Where are the cardiac centers located?

Back 48

the medulla oblongata

Front 49

Cardioacceleratory center innervates?

Back 49

SA and AV nodes, heart muscle, and coronary arteries through sympathetic neurons

Front 50

Cardioinhibitory center inhibits?

Back 50

SA and AV nodes through parasympathetic fibers in the vagus nerves

Front 51

Electrocardiogram (ECG or EKG):

Back 51

a composite of all the action potentials generated by nodal and contractile cells at a given time

Front 52

What are the 3 waves?

Back 52

1. P wave: depolarization of SA node

2. QRS complex: ventricular depolarization

3. T wave: ventricular repolarization

Front 53

Cardiac cycle:

Back 53

all events associated with blood flow through the heart during one complete heartbeat

Front 54

contraction

Back 54

Systole

Front 55

relaxation

Back 55

Diastole

Front 56

Ventricular filling

Back 56

takes place in mid-to-late diastole

Front 57

Ventricular filling process

Back 57

• AV valves are open

• 80% of blood passively flows into ventricles

• Atrial systole occurs, delivering the remaining 20%

• End diastolic volume (EDV): volume of blood in each ventricle at the end of ventricular diastole

Front 58

When does Isovolumetric relaxation occur?

Back 58

in the early diastole

Front 59

Isovolumetric relaxation process

Back 59

• Ventricles relax

• Backflow of blood in aorta and pulmonary trunk closes SL valves and causes dicrotic notch (brief rise in aortic pressure)

Front 60

What is the cardiac Output (CO)

Back 60

• Volume of blood pumped by each ventricle in one minute

Front 61

What is the CO equation?

Back 61

• CO = heart rate (HR) x stroke volume (SV)

Front 62

What is the HR & SV?

Back 62

• HR = number of beats per minute

• SV = volume of blood pumped out by a ventricle with each beat

Front 63

What is the CO at rest?

Back 63

• CO (ml/min) = HR (75 beats/min) × SV (70 ml/beat) = 5.25 L/min

Front 64

What is the maximal CO?

Back 64

4–5 times resting CO in nonathletic people

• Maximal CO may reach 35 L/min in trained athletes

Front 65

Cardiac Reserve:

Back 65

difference between resting and maximal CO

Front 66

Regulation of stroke volume equation

Back 66

• SV = EDV – ESV

Front 67

Three main factors affect SV

Back 67

• Preload

• Contractility

• Afterload

Front 68

preload

Back 68

degree of stretch of cardiac muscle cells before they contract (Frank-Starling law of the heart)

Front 69

preload process

Back 69

• Cardiac muscle exhibits a length-tension relationship

• At rest, cardiac muscle cells are shorter than optimal length

• Slow heartbeat and exercise increase venous return

• Increased venous return distends (stretches) the ventricles and increases contraction force

Front 70

Contractility

Back 70

contractile strength at a given muscle length, independent of muscle stretch and EDV

Front 71

what do positive inotropic agents do?

Back 71

increase contractility

• Increased Ca2+ influx due to sympathetic stimulation

• Hormones (thyroxine, glucagon, and epinephrine)

Front 72

What do inotropic agents do?

Back 72

decrease contractility

• Acidosis

• Increased extracellular K+

• Calcium channel blockers

Front 73

Regulation of Stroke Volume

• Afterload:

Back 73

pressure that must be overcome for ventricles to eject blood

Front 74

What does hypertension increase?

Back 74

afterload, resulting in increased ESV and reduced SV

Front 75

What factors increases the heart rate?

Back 75

Positive chronotropic

Front 76

What factors decrease the heart rate?

Back 76

Negative chronotropic

Front 77

What is activated by emotional or physical stressors?

Back 77

The Sympathetic nervous system

Front 78

What causes the pacemaker to fire more rapidly (and at the same time increases contractility)

Back 78

Norepinephrine

Front 79

What system opposes sympathetic effects?

Back 79

Parasympathetic nervous

Front 80

How does the Acetylcholine hyperpolarizes pacemaker cells?

Back 80

by opening K+ channels

Front 81

What does the heart at rest exhibit?

Back 81

Vagal tone (parasympathetic)

Front 82

What Factors Influence Heart Rate?

Back 82

• Age

• Gender

• Exercise

• Body temperature

Front 83

Tachycardia:

Back 83

abnormally fast heart rate (>100 bpm)

Front 84

If tachycardia is persistent,it may lead to ____?

Back 84

fibrillation

Front 85

Bradycardia:

What might it result in?

Back 85

heart rate slower than 60 bpm

• May result in grossly inadequate blood circulation

• May be desirable result of endurance training