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A And P 2 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

What is a PVC?

A

When the heart contracts prematurely / extrasystole

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2
Q

How are parasympathetic impulses transmitted from the brain to the heart?

A

Cardioinhibitory center sends impulses through the vagus nerve to decrease HR

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3
Q

How are sympathetic impulses transmitted from the brain to the heart?

A

The cardioacceleratory center sends impulses through the sympathetic trunk - stimulates the SA node, AV node, myocardium, and the coronary arteries to increase HR and contractility

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4
Q

How do these autonomic systems change the heart rate?

A

Through the cardiac centers in the medulla oblongata

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5
Q

What does the PNS do to HR?

A

Can decelerate it

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6
Q

What is the role of artificial pacemakers?

A

Medical devices that decouple the atria and ventricles - can be programmed to change with changing energy demands and interrogates to with symptoms appear

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7
Q

What is partial heart block?

A

Only some impulses get through

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8
Q

What is total heart block?

A

No impulses get through, the ventricles beat at their own intrinsic rate - too slow for adequate tissue perfusion

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9
Q

Why can a PVC feel like a thud in the chest?

A

Afterwards, the heart has a slightly longer time to fill and the next normal contraction feels like a thud with more fluid

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10
Q

What is an ICD?

A

Implantable cardioverter defibrillator, devices that continually monitor heart rhythms, they will slow tachycardia and emit an electrical shock in the event of fibrillation

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11
Q

What is defibrillation?

A

electrically shocking the heart to depolarize the entire myocardium - ideally, the SA node begins to function normally and sinus rhythm is restored

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12
Q

What is fibrillation?

A

Rapid or irregular contractions of the heart

control of heart by SA node is disrupted

Fibrillation ventricles are not useful pumps

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13
Q

What is an arrhythmia?

A

Irregular heart rhythm resulting from a defect in the intrinsic conduction system

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14
Q

What is the intrinsic rate set by the AV bundle/Purkinje fibers?

A

30 beats per min

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15
Q

What is the intrinsic rate set by the AV node?

A

50 beats per min

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16
Q

What is the intrinsic rate set by the SA node?

A

75 beats per min

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17
Q

What is the only electrical connection between the atria and ventricles?

A

AV bundle

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18
Q

Why is there a delay at the AV node?

A

It allows the atria to complete their contraction

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19
Q

How long does it take an impulse to pass through the entire heart?

A

0.22s or 220ms

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20
Q

What is the sequence of excitation of the heart?

A

Sinoatrial node (SA Node)

Atrioventricular node (AV node)

AV bundle / Bundle of His

Right and left bundle branches

Punkinje fibers (subendocardial conducting network)

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21
Q

What is repolarization?

A

K+ channels open, K+ effluxes, cell’s interior becomes more negative

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22
Q

What is depolarization?

A

Ca2+ channels open (around -40mV), Ca2+ influxes leading to an AP

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23
Q

What is the intrinsic conduction system?

A

Noncontractile cells specialized to initiate and distribute impulses throughout the heart

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24
Q

What is the difference between cardiac myocytes and cardiac muscle regarding aerobic respiration?

A

cardiac myocytes are dense in mitochondria reflecting a great dependence on oxygen

Cardiac muscle is more adaptable to using different nutrient sources as fuel

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25
What is tetany?
In cardiac muscle, the refractory period is longer than contraction to prevent tetany
26
What is summation?
Occurs in skeletal muscle because the refractory period is short than contraction
27
What is the absolute refractory period?
The period during an AP when an additional AP cannot be generated
28
What does depolarization do in cardiac muscle?
Depolarization opens special, slow flow Ca2+ channels in the cell membrane - the combination of extracellular Ca2+ and Ca2+ from the Sarcoplasmic Reticulum allows contraction
29
What is automaticity/audtorhythmicity?
The ability to spontaneously depolarize self generated depolarizations travel throughout the heart via gap junctions No neural input is needed for cardiac myocytes
30
What are pacemaker cells?
Self excitable, non-contractile cells, SA node
31
What is the coronary sinus?
cardiac veins merge to form coronary sinus
32
What is the bicuspid mitral valve?
1 of the 2 AV valves, between LA and LV, 2 flexible cusps
33
What branches off the descending aorta?
All other systemic arteries
34
What is the physiology of cardiac tamponade?
Compression of the heart by large amounts of inflammatory fluid in pericardial cavity hearts ability to pump blood is reduced Management: removal of excess fluid by syringe
35
How is calcium delivered?
Fewer, wider, T tubules, 1 per sarcomere, regulate calcium concentration
36
What are sarcomeres made of?
Myosin, actin, Z discs, A bands, and I bands
37
What are myosin and actin?
Thick and thin myofilaments part of the sarcomere
38
What is a functional syncytium?
When the myocardium acts as a single coordinated unit
39
What are gap junctions?
Part of the intercalated discs, allow ions to pass from cell to cell - transmitting current across the entire heart
40
What are desmosomes?
Part of intercalated discs, orevtns separation during contraction
41
What are intercalated discs?
Junctions that the plasma membranes of adjacent cardiac myocytes interlock at
42
What part of cardiac myocyte volume does large mitochondria account for?
25-35%
43
How does the cardiac muscle contract?
It contracts via the sliding filament mechanism - sarcomeres
44
What is the anatomy of the cardiac muscle?
striated like skeletal muscle Contracts via sliding filament mechanism - sarcomeres Cardiac myocytes are shorter and fatter than skeletal muscle cells - they are more branched and interconnected Each myocyte has 1 or 2 centrally located nuclei Large mitochondria account for 25-35% of cardiac myocyte volume Cardiac myocytes push and pull on the cardiac skeleton striated like skeletal muscle
45
What is angina pectoris?
Thoracic pain caused by a fleeting deficiency in blood supply to myocardium Causes increased physical al demands on heart (I.e. exercise), stress induced spasms of the coronary arteries, myocardial cells will weaken but not die
46
Where does the coronary sinus empty its blood?
It drains into the RA
47
What are the 3 major venous tributaries to the coronary sinus?
great cardiac vein from the anterior interventricular sulcus Middle cardiac vein from the posterior interventricular sulcus Small cardiac vein from the right inferior margin - anterior cardiac veins empty directly into the RA
48
What’s an anastomosis?
Cross connection between adjacent channel
49
When is the myocardium perfused - during ventricular systole or diastole?
Diastole
50
What are the symptoms of a myocardial infarction?
Male: chest squeezing, pressure, discomfort, shortness of breath, upper back pain, pain down at least 1 arm, jaw pain, feeling of fullness, and nausea Female: chest discomfort, shortness of breath, upper back pain, pain down at least 1 arm, jaw pain, unexplained/extreme fatigue, fainting, vomiting, nausea, sudden dizziness
51
What medical condition results from a partial or complete blockage in the coronary circulation?
Myocardial infarction
52
What branches off the right coronary artery and what parts of the myocardium it supplies?
Serves the right side of the heart right marginal artery; supplies myocardium of lateral right side of heart Posterior interventricular artery: supplies the apex of heart and the posterior ventricular walls
53
What branches off the left coronary artery and what part of the myocardium does it supply?
Serves the left side of heart anterior inter ventricular artery (left anterior descending artery): follows the anterior inter ventricular sulcus, supplies blood to the anterior walls of both ventricles and inter ventricular septum Circumflex artery: supplies the LA and posterior wall of LV
54
Where do the coronary vessels exist on the surface of the heart?
R and l coronary arteries arise from base of aorta and travel around heart in the coronary sulcus
55
What is the function of coronary circulation?
In the epicardium, functional blood supply to myocardium
56
What blood is carried by pulmonary veins?
They carry oxygen-rich blood from the lungs to the LA
57
What is blood is carried by the pulmonary trunk/arteries?
Carries oxygen-poor blood from RV to lungs
58
What branches off the aortic arch?
Brachiocephalic trunk, L common carotid artery, and L subclavian artery
59
What branches off the ascending aorta?
R and L coronary arteries
60
What are exceptions to the oxygenation of the arteries and veins?
Pulmonary trunk (artery) carries oxygen-poor blood from arm to lungs Pulmonary veins carry oxygen rich blood from lungs to LA
61
What do veins do for the circulatory loop?
Returns blood to the heart that is typically oxygen-poor
62
What do arteries do for the circulatory loop?
Carries blood away from heart that is typically oxygen rich
63
Which side of the heart pumps blood into the pulmonary circuit?
The right side is the pulmonary circuit pump, which is short and lower pressure
64
Which side of the heart pumps blood into the systemic circuit?
The left side is the systemic circuit pump, which is longer and has higher resistance
65
What are the dangers of stenotic valves?
They are stiff and narrows, constricting the heart’s openings narrow openings force the heart to contract more forcefully Mitral and aortic valves are often affected
66
What are the dangers of insufficient valves?
It forces the heart to repump the same blood multiples times, faulty valve increases heart workload - weakening the heart over time leaky valves reduce efficiency of pumping heart
67
What causes SL valves to close?
Close as blood back flows toward the heart and fills the cusp
68
What causes SL valves to open?
Forced open as ventricles contract and pressure rises
69
What are the SL valves?
Includes aortic and pulmonary valves. They guard the bases of the large arteries emerging from each of the ventricles, preventing back-flow from vessel to ventricle They open and close in response to changes in pressure; forced open as ventricles contract and pressure
70
What is a cusp?
Flap of endocardium
71
What is the tricuspid valve?
1 of the 2 AV valves, between RA and RV, 3 flexible cusps
72
What are the AV valves?
2 total (Tricuspid and mitral valves) that are located at each atrial ventricular junction, prevents backflow of blood into atria during ventricular contraction
73
How is blood propelled from ventricles?
Ventricular contraction propels blood out of the heart and into circulation Blood propelled from RV is in pulmonary trunk Blood propelled from LV is in the aorta
74
what is the difference between the left and right ventricles?
The left ventricle’s myocardial wall is 3x thicker than right ventricle
75
What are the ventricles?
They make up most of the volume of the heart and have much thicker myocardial walls than atria includes trabeculae carneae and papillary muscles
76
What is the anatomy and physiology of the LA?
The walls are smooth and blood enters via the 4 pulmonary veins
77
What is the anatomy and physiology of the RA?
Anterior wall of RA is covered with bundles of muscles called pectinate muscles, blood enters RA via the coronary sinus, SVC, and IVC
78
What is the atria?
Small receiving chambers, generate only minimal contraction to push blood into the ventricles; includes right atrium, left atrium. and fossa ovalis
79
how many and what chambers are in the heart?
4 chambers, 2 atria, 2 ventricles
80
What is the chordae tendineae and its function?
Irregular ridges of muscle that lines the internal walls of ventricular chambers
81
What are papillary muscles and its function?
Muscles that project into ventricular chambers and play a role in valve function
82
What is the function of the auricles?
small wrinkled appendages that sit atop each atrium Expands the volume capacity of the right and left atria as needed
83
What is the physiology of pericarditis?
The inflammation of the pericardium beating heart runs against pericardial sac - audible sound produced Sx; pain deep to the sternum Leads to adhesions, impeded cardiac activity
84
What is the function of cardiac skeleton?
A reinforcing, dense network formed by CT fibers, skeleton prevents overstretching from continuous stresses and ensures that action potentials only spread along desired pathways
85
What is the endocardium?
The deepest layer of heart wall made of endothelium; lines the heart chambers, contiguous with lining of the great vessels
86
What is the myocardium?
The middle muscle layer of heart wall; composed of contracting, cardiac muscle, bulk of heart; cardiac muscles arranged in spiral bundle thethered to each other by crisscrossing CT fibers, cardiac skeleton
87
What is the epicardium?
It’s the visceral pericardium and most superficial layer of heart wall
88
What is the contents and function of pericardial cavity?
Space between parietal and visceral layers, filled with serous fluid, functions to reduce friction
89
What is visceral layer?
Layer of serous pericardium, lines the external surface of the heart
90
What is the parietal layer?
Layer of serous pericardium, lines internal surface of the fibrous pericardium
91
What is serous pericardium?
Deep to the fibrous pericardium, made of 2 thin layers
92
What is fibrous pericardium?
Loose fitting superficial part of the pericardium, made of DCT, protects the heart; keeps it from overfilling and anchors to mediastinum
93
What is the pericardium?
The double-walled sac that encloses the heart
94
Describe the apex of the heart
Points inferiority to left hip
95
Describe the base of the heart
Wide, flat, posterior surface, directed to right shoulder
96
Where is the heart located?
Within mediastinum, midline thoracic cavity between sternum and vertebral column, rests on diaphragm, 2/3 of mass to left of midstream, line
97
What is the shape of the heart?
Hollow cone-shaped structure
98
What size is the heart?
Less than a lb, human fist
99
Which side of the heart is the systemic circuit?
Left side (aortic valve, body, LA, LV)
100
Which side of the heart is the pulmonary circuit?
Right side (venae cavae, SVC, RA, RV)
101
Which side of the heart has oxygenated blood?
Left side of the heart receives oxygen-rich blood
102
Which side of the heart has deoxygenated blood?
right side of the heart receives oxygen-poor blood
103
What does the SNS do to HR?
Can accelerate it and increase contractility

A And P 2 (14 decks)

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