Circultory System: Heart Flashcards
(112 cards)
1
Q
Cardiology
A
Study of the heart and its associated diseases
2
Q
Pulmonary circuit
A
Carries blood to lungs for gas exchange and returns it to heart; supplied by right side of heart
Pumps O2 poor blood to lungs via pulmonary trunk
3
Q
Systemic circuit
A
Supplies blood to every organ of the body including other parts of the lungs and wall of the heart; supplied by left side of the heart
Pulmonary veins return oxygen rich blood to heart; blood leaves heart via aorta and returns via superior/inferior vena cava
4
Q
Mediastinum
A
the space in the chest between the lungs, breastbone, and spine. It contains the heart, lungs, esophagus, trachea, thymus, and lymph nodes
5
Q
Base of heart
A
Wide, superior portion of heart, large vessels attach here
6
Q
Apex of heart
A
Tapered inferior end, tilts of left
7
Q
Heart is the size of what?
A
A fist
8
Q
Pericardium
A
Double walled sac that encloses heart
Allows heartbeat without friction, provides room to expand while resisting excessive expansion
Anchored to diaphragm and sternum
9
Q
Fibrous pericardium
A
Outer wall, not attached to heart
10
Q
Serous pericardium
A
Composed of a parietal layer and visceral layer
11
Q
Parietal later
A
Lines fibrous epicardium
12
Q
Visceral layer (epicardium)
A
Covering heart surface
13
Q
Pericardial cavity
A
Space between parietal and visceral layers of serous pericardium, filled with 5-30 mL of pericardial fluid
14
Q
Pericarditis
A
Painful inflammation of the membranes surrounding the heart
15
Q
3 layers of heart wall
A
Epicardium
Myocardium
Endocardium
16
Q
Epicardium
A
Visceral layer of serous pericardium
Serous membrane covering heart
Adipose in thick layer in some places
Coronary blood vessels travel through this layer
17
Q
Myocardium
A
Layer of cardiac muscle proportional to workload
Muscle spirals around heart
Fibrous skeleton of heart; framework of collagenous and elastic fibers
Provides structural support
Provides electrical insulation between atria/ventricles (important for contraction)
18
Q
Endocardium
A
Smooth inner lining of heart and blood vessels
Covers valve surfaces and is continuous with endothelium of blood vessels
19
Q
Vortex of the heart
A
Refers to the spiral orientation of myocardial muscle
20
Q
Upper chambers of heart
A
Left and right atria
21
Q
Lower chambers of heart
A
Left and right ventricles
22
Q
Both ventricles have the same _____
A
Volume
23
Q
Atrioventricular (AV) valves
A
Regulate the openings between the atria and the ventricles
24
Q
Right AV valve
A
Three cusps; tricuspid valve
25
Left AV valve
Two cusps; mitral (aka bicuspid) valve
26
Chordae tendinae
Attach the valves to the papillary muscles on the floor of the ventricle
Stop valves from flipping inside out or bulging into the atria when ventricles contract
27
Semilunar Valves
Regulate blood flow from ventricles into the great arteries
Prevent back flow into ventricles as cusps act like a seal
Both have three cusps
Aortic valve
Pulmonary valve
28
Aortic valve
Controls opening from left ventricle to the aorta
29
Pulmonary valve
Controls opening from right ventricle to pulmonary trunk
30
Pulmonary valve
Controls opening from right ventricle to pulmonary trunk
31
What causes the valves of the heart to open/close?
Changes in pressure during contraction and relaxation
32
Blood flow through heart
1. Deoxygenated blood enters right atrium from superior & inferior vena cava; blood flows through tricuspid valve to right ventricle
2. Contraction of right ventricle forces pulmonary valve open
3. Blood throws through pulmonary valve into pulmonary trunk
4. Blood distributed via pulmonary arteries to the lungs where CO2 is unloaded and O2 is loaded
5. Blood return to left atrium via pulmonary veins
6. Blood flows through mitral valve to left ventricle
7. Contraction of left ventricle (simultaneous with slight contraction) forces aortic valve open
8. Blood flows through aortic valve into ascending aorta
9. Blood in aorta is distributed to every organ in the body where O2 is unloaded and CO2 is picking up
10. Deoxygenated blood returns to right atrium via vena cava
33
Coronary circulation
5% of blood pumped by heart is pumped to the heart itself through the coronary circulation to sustain its strenuous work load
250 mL per min
Needs abundant O2 and nutrients
34
Left coronary artery (LCA)
Branches off ascending aorta
35
Anterior interventricular branch
Supplies blood to both ventricles and anterior two thirds of the interventricular septum
36
Circumflex branch
Passes around left side of heart in coronary sulcus
Gives off left marginal branch and ends on posterior side of heart
Supplies left atrium and posterior wall of left ventricle
37
Right coronary artery
Branches of ascending aorta
Supplies right atrium and sinoatrial node
38
SA noda is also known as what?
Pacemaker
39
Right marginal branch
Supplies lateral aspect of right atrium and ventricle
40
Posterior interventricular branch
Supplies posterior walls of ventricles
41
Angina pectoris
Chest pain from partial obstruction of coronary blood flow
Pain caused by ischemia of cardiac muscle
Obstruction partially blocks blood flow
Myocardium shifts to anaerobic fermentation producing lactate which stimulates pain
42
Ischemia
Lack of blood supply to a part of the body
43
Myocardial infarction
Sudden death of a patch of myocardium resulting from long term obstruction of coronary circulation
44
Atheroma
Blood clot or fatty deposit that obstructs coronary arteries
45
The conduction system of SA node
Coordinates the heartbeat
Composed of an internal pace maker and nerve like do caution pathways through myocardium
Follows this order:
Sinoatrial node (SA node): modified cardiomyocytes
- pacemaker initiates each heartbeat and determines rate
- pacemaker in right atrium near base of superior vena cava
- signals spread throughout atria
46
Conduction of AV node
Located near AV valve at lower end of interatrial septum
Electrical gateway to ventricles
Fibrous skeleton prevents electrical currents from getting to ventricles by any other route
47
AV bundle of His
Bundle forks into R&L bundle branches
Branches through interventricular septum toward apex
48
Subendothelial conducting networks
Nerve like process spread throughout ventricular myocardium
Cardiomyocytes then paws signal from cell to cell through gap junctions
49
Conduction system pathway
1. SA node fires
2. Excitation spreads through atrial myocardium
3. AV nod fires
4. Excitation spreads down AV bundle
5. Subendocardial conducting network distributes excitation through ventricular myocardium
50
Systole
Contraction of heart
51
Diastole
Relaxation of heart
52
Sinus rythym
Normal heartbeat triggered by the SA node
Adult at rest is typically 70 to 80 bpm (vagal tone)
53
Ectopic focus
A region of spontaneous firing other than the SA node
May govern heart rythym if SA node damaged
54
Nodal rythym
If SA node is damaged, heart rate is set by AV node, 40 to 50 bpm
Other ectopic focal rythyms are 20 to 30 bpm and too slow to sustain life
55
Cardiomyocytes
Striated, short, thick, branched cells, one structural nucleus surrounded by light staining mass of glycogen
56
Intercalated discs
Join cardiomyocytes end to end with three features: interdigitating folds, mechanical junctions & electrical junctions
57
Electrical junctions
A gap junction that can transmit action potentials between neurons
58
Mechanical junction
59
Structure of cardiac muscle
- mechanical junctions tightly join cardiomyocytes
- fascia adherens
- desmosomes
- electrical junctions ( gap junctions)
60
Fascia adherens
Broad band in which the actin of the thin myofilaments is anchored to the plasma membrane
- each cell is linked to the next via transmembrane proteins
61
Desmosomes
Mechanical linkages that prevent contracting cardiomyocytes from being pulled apart from each other
62
Electrical junctions (gap junctions)
Allow ions to flow between cells; can stimulate neighbours
Entire myocardium of either two atria or two ventricles acts like single, unified cell
63
Sinus rythym
Normal heartbeat triggered by SA node
Adults typically 70-80bpm
64
Ectopic focus
Region of spontaneous firing other than the SA node
May govern heart rhythm of SA node is damaged
65
Nodal rhythm
If SA node is damaged, heart rate is set by AV node, 40 to 50 bpm
Other ectopic rythyms are 20 to 40 bpm and too slow to sustain life
66
Electrical behaviour of myocardium steps
1. Voltage gated Na+ channels open
2. Na+ inflow depolarizes membrane, triggers opening of more Na+ channels, creates positive feedback cycle and rapidly rising membrane voltage
3. Na+ channels close when cell depolarizes, voltage peaks around +30mV
4. Ca2+ enters slowly through Ca2+ channels, prolonging depolarization of membrane. Plateau falls slightly from K+ leakage but most K+ channels remain closed until end of plateau
5. Ca2+ channels close and Ca2+ is transported out of cell, K+ channels open and rapid K+ outflow returns membrane to its resting potential
67
Refractory period of electrical behaviour of myocardium
The refractory period is much longer to prevent summation and tetanus
68
Electrocardiography (ECG or EKG)
Composite of all action potentials of nodal and myocardial cells detected, amplified and recorded by electrode on arms, legs, and chest
69
P Wave
SA node fires, atria depolarizes and contract; atrial systole begins 100ms after SA signals
70
PR Interval
Signal conduction through AV node, before activating ventricles
71
QRS complex
Ventricular depolarization; complex shape of spike due to different thickness and shape of the two ventricles
72
QT interval
Duration of ventricular depolarization; shorter during excercise
73
ST segment
Ventricular systole; corresponds to plateau in myocardial action potential
74
T wave
Ventricular depolarization and relaxation
75
Ventricular fibrillation
Serious arrhythmia caused by electrical signals travelling randomly
Heart cannot pump blood; no coronary perfusion
Hallmark of heart attack (MI)
Kills quickly if not stopped
76
Defibrillation
Strong electrical shock with intent to depolarize entire myocardium and reset heart to sinus rhythm
77
Atrial fibrillation
Chaotic depolarizations that do not stimulate ventricles; common in elderly and alcoholics
78
Heart block
Failure of any part of the cardiac conduction system to conduct signals, usually result of disease or degeneration of conduction system
79
Premature ventricular contraction
Ventricular ectopic focus with extra beat; may result from stress, lack of sleep or stimulants
80
Cardiac cycle
One complete contraction and relaxation of all four chambers of the heart
81
Cardiac Output Equation
SV x HR
82
S1
First heart sound
Heart during closure of AV valves, turbulence in blood stream and movements of heart wall
Louder and longer “lubb”
83
S2
Second heart sound
Softer sharper “dupp”
Occurs during closure of semilunar valves, turbulence in blood stream and movements of heart wall
84
S3
Rarely heard in people over 30
85
3 phases of ventricular filling
1. Rapid filling
2. Diastasis (slower filling, P wave at end)
3. Atrial systole
86
Isovolumetric contraction
Ventricles depolarize, generate the QRS complex, ventricles contract
87
Ventricular ejection
Ventricular pressure exceeds arterial pressure
T wave occurs late in this phase
88
Isovolumetric relaxation
Ventricular diastole
89
What happens if right ventricular output exceeds left ventricular output?
Pressure backs up and fluid accumulates in pulmonary tissue
90
What happens if left ventricular output exceeds RV output?
Pressure backs up and fluid accumulates in systemic tissue
91
Congestive Heart Failure (CHF)
Fluid accumulation in either circuit due to insufficient ventricular pumping
92
Sympathetic ANS input
Increases HR, increases strength and contraction; Norepinephrine
93
Parasympathetic ANS input
Decreases HR, parasympathetic influence dominates; ACh
94
SV
Stroke volume (ml/beat)
95
HR
Heart rate (beats/min)
96
Cardiac reserve
Difference between a persons maximum and resting CO
97
Pulse
Surge of pressure produced by heartbeat that can be felt by palpating a superficial artery
98
Tachycardia
Resting adult heart rate above 100 bpm
Stress, anxiety, heart disease, fever
Loss of blood or damage to myocardium
99
Bradycardia
Resting adult heart rate of less than 60 bpm
In sleep, low body temp, endurance trained athletes
100
Positive chronotropic agents
Factors that raise the heart rate
101
Negative chronotropic agents
Factors that lower the heart rate
102
3 factors that govern stroke volume
1. Preload
2. Contractility
3. After load
103
Preload
The amount of tension in ventricular myocardium immediately before it begins to contract
104
Contractility
Refers to how hard the myocardium contracts for a given preload
105
Afterload
Sum of all forces opposing ejection of blood from ventricle
106
Frank starlings law of heart
- stroke volume = proportional to the end of diastolic volume
- ventricles eject almost as much blood as they receive
- the more they are stretched, the harder they contract
- relates to length-tension relationship of striated muscle
107
Factors for increased HR
- positive chronotropic agents
- sympathetic nervous system
- thyroid hormone
- glucagon
- nicotine, caffeine
- hypocalcemia
108
Factors for increased SV
- increased preload
- positive inotropic agents
- sympathetic nervous system
- epinephrine, norepinephrine
- glucagon
- digitalis
- nicotine, caffeine
- hypercalcemia
109
Reduced HR
- negative chronotropic agents
- parasympathetic nervous system
- acetylcholine
- hypercalcemia
- hypokalemia
- beta blockers
110
Reduced SV
- reduced preload
- reduced contractility
- increased afterload
- negative inotropic agents
- hypocalcemia
- hyperkalemia
111
Coronary artery disease
Constriction of coronary arteries due to atherosclerotic plaques that narrow arteries and decrease blood flow to myocardium, arterial walls thicken and lose elasticity
112
Risk factors for coronary artery disease
High cholesterol
High BP
Diabetes mellitus
Smoking
Obesity
Sedentary lifestyle
Type A personality
Genetics
Age
