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A and P II Exams > Exam 1: Heart > Flashcards

Exam 1: Heart Flashcards

1
Q

Heart Location

A
  • Mediastinum: the cavity in the thorax which contains the heart
  • extends from the 2nd rib to the 5th intercostal space
  • rests on the superior surface of the diaphragm
  • about 2/3 of the heart lies to the left of the midsternal line
  • flat base on the posterior surface
  • apex that points inferiorly toward the left hip
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2
Q

Heart Covering

A

From superficial to deep:

  • Fibrous Pericardium
  • Serous Pericardium
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3
Q

Fibrous Pericardium

A
  • dense connective tissue
  • protects the heart
  • anchors the heart to surrounding structures
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4
Q

Serous Pericardium

A
  • thin
  • two-layers
  • — parietal layer: lines the inside of the fibrous pericardium
  • — visceral layer: attached to the external heart surface and is called the epicardium
  • — between the layers: pericardial cavity containing serous fluid lubricating the outside of the heart
  • — loss of fluid creates painful pericarditis
  • — cardiac tamponade: too much fluid which restricts the heart’s activity
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5
Q

Layers of the Heart

A

From Superficial to Deep:

  • Epicardium (visceral pericardium)
  • Myocardium
  • Endocardium
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6
Q

Myocardium

A
  • forms the bulk of the heart

- consists mostly of cardiac muscle

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7
Q

Endocardium

A
  • thin layer of squamous epithelium and connective tissue that lines the chambers of the heart
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8
Q

Chambers of the Heart

A
  • Right Atria and Left Atria
  • — relatively small and thin-walled because their function is only to collect blood and pass it to the ventricles
  • — atria are separated by the interatrial septum
  • — right and left auricles protrude from the atria like ears
  • — pectinate muscle: raised bundles line interior surface
  • — fossa ovalis
  • Right Ventricle
  • Left Ventricle
  • — ventricles are separated by the interventricular septum
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9
Q

Fossa Ovalis

A
  • shallow depression within the interatrial septum
  • in fetal life, this was the foramen ovale
  • – blood passed directly from right to left atrium
  • — this opening closes shortly after birth
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10
Q

Blood enters the right atrium from

1, 2, and 3

A
  1. superior vena cava - drains the upper part of the body
  2. inferior vena cava - drains the lower part of the body
  3. coronary sinus - drains the myocardium
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11
Q

Blood enters the left atrium from….

A
  • the pulmonary veins
  • — two from the right, and two from the left
  • — transport oxygen rich blood from the lungs back to the heart
  • left atrium makes up most of the heart’s base
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12
Q

Ventricles

A
  • make up most of the heart volume
  • trabeculae carnae: irregular ridges of muscles on the interior surface
  • papillary muscles: cone-like muscles which connect to the valves
  • thickened walls because of the amount of work required to pump the blood greater distances
  • when the ventricles contract, blood is forced into circulation
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13
Q
  1. Right ventricle sends blood through….

2. Left ventricle sends blood through….

A
  1. the pulmonary trunk
    - divides into the right and left pulmonary arteries
    - blood goes to lungs
  2. aorta
    - largest artery of the body
    - blood goes out to body tissues
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14
Q

Pulmonary Circuit

A
  • the right side of the heart collects O2-poor and CO2-rich blood from the body and pumps it to the lungs where CO2 is unloaded and O2 is picked up
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15
Q

Systemic Circuit

A
  • the left side of the heart collects O2-rich and-CO2 poor blood and pumps it to the arteries where it is transported to the body tissues
  • in the body, O2 is dropped off and CO2 is picked up
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16
Q

How the heart tissue gets nutrients

A
  • the heart picks up almost no O2 or nutrients from the chambers of the heart, but has its own coronary circulation
  • the right and left coronary arteries arise from the base of the aorta and encircle the heart in the atrioventricular groove
  • — left –> anterior interventricular artery (LAD) and circumflex artery
  • — right –> marginal artery and posterior interventricular artery
  • considerable variation among people in the arterial blood supply of the heart
  • many anastomoses among the arterial branches
  • — a grid of arteries which allows for detours to be taken if an artery is blocked
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17
Q

Cardiac Veins

A
  • collect blood after it passes through the capillary beds of the myocardium
  • Three large veins
  • — great cardiac, middle cardiac, small cardiac
  • — drain into the coronary sinus which empties into the right atrium
  • several anterior cardiac veins also empty into the right atrium
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18
Q

Myocardial Infarction

A
  • heart attack
  • — lack of blood flow to one area of the heart
  • can be caused by an arterial blockage in the coronary circulation
  • cell death due to oxygen deprivation results in tissue replacement with scar tissue
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19
Q

Heart Valves

A
  • two atrioventricular valves
  • — tricuspid and mitral
  • two semilunar valves
  • — aortic and pulmonary
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20
Q

Atrioventricular Valves

A
  • regulate flow of blood between the atrium and the ventricle on the same side
  • — tricuspid on the right
  • — mitral/bicuspid on the left
  • valve flaps are connected to papillary muscles by collagen cords called chordae tendinae
  • when the ventricle contracts, the valve closes preventing backflow into the atrium
  • — papillary muscles also contract preventing the flaps from going into the atrium
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21
Q

Semilunar Valves

A
  • prevent backflow of blood back into the ventricle
  • — Aortic Valve: between the left ventricle and the aorta
  • – Pulmonary Valve: between the right ventricle and pulmonary trunk
  • when the ventricle contracts, the semilunar valve is forced open
  • when the ventricle is relaxed, backpressure of the aorta/pulmonary trunk forces the semilunar valve closed
22
Q

Cardiac Muscle

A
  • striated and contracts by sliding filaments
  • — like skeletal muscle
  • has only one or two centrally located nuclei
  • a greater portion of the the cell is made up of mitochondria
  • — heart relies almost exclusively on aerobic respiration
  • — cardiac muscle cannot incur much oxygen debt
  • intercalated discs
  • gap junctions
23
Q

Intercalated discs

A
  • found in the junctions of cardiac muscle cells
  • contain anchoring desmosomes
  • — prevent separation of cells during contraction
24
Q

Gap Junctions

A
  • found in the junctions of cardiac muscle cells
  • allow ions to pass from cell to cell
  • — this electrical coupling allows the entire myocardium to act as a coordinated unit
25
Q

Intrinsic Caidiac Conduction System

A
  • autorhythmic cells: non-contractile cardiac cells
  • able to to initiate action potentials that spread throughout the heart
  • note: the heart is well supplied with nerves which can alter the rhythm
26
Q

Sequence of Excitation

A
  1. Sinoatrial node
  2. Atrioventricular node
  3. Bundle of His
  4. Purkinje Fibers
  5. Ventricular Muscle Cells
27
Q

Sinoatrial Node

A
  • located on the right atrial wall just inferior to the entrance of the superior vena cava
  • heart’s pacemaker: determining the sinus rhythm
  • — contain autorhythmic cells
  • start the sequence of excitation
28
Q

Atrioventricular Node

A
  • recieve impulse after the sinoatrial node
  • — step 2 of excitation
  • —a wave of depolarization spreads via gap junctions throughout the atrium to the AV node
  • located on the inferior interatrial septum
  • impulse is delayed, allowing the complete contraction of the atrium
29
Q

Bundle of His

A
  • receive impulse after the atrioventricular node
  • — step 3 of excitation
  • located in the superior part of the interventricular septum
  • this is the only electrical connection between the atria and the ventricles
  • splits into right and left bundle branches that the impulse continues along
30
Q

Purkinje fibers

A
  • receives the impulse from the branches of the Bundle of His
  • — step 4 of excitation
  • reach down to the apex and then into the ventricular walls
  • —- walls: cell to cell transmission via gap junctions occurs between ventricular muscle cells
31
Q

Arrhythmias

A
  • irregular atrial or ventricular contractions
32
Q

Fibrillation

A
  • condition of rapid and irregular or out-of-phase contractions in which contractions are no longer controlled by the sinoatrial node
  • an electrical shock to the heart may allow the sinoatrial node to regain control of rhythms
  • — defibrillation
  • — depolarizes the entire myocardium
33
Q

EKGs

A
  • an electrocardiograph records electrical currents generated in the heart and spread through the heart and the body
  • three distinguishable waves
  • — small P wave
  • — QRS complex
  • — T wave
  • the size, duration, and timing of the deflection waves tend to be consistent in a healthy heart so that changes in patterns may reveal disease or past damage
34
Q

P wave

A
  • small

- depolarization wave from the sinoatrial node through the atria

35
Q

QRS complex

A
  • results from ventricular depolarization and precedes ventricular contraction
  • obscures a graphical recording on the EKG of atrial repolarization
  • — bc atrial repolarization occurs at the same time as ventricular depolarization
36
Q

T wave

A
  • caused by ventricular repolarization
37
Q

Normal Heart Sounds

A
  • lub-dup sound is associated with closing of heart valves
  • lub: when AV valves close
  • — ventricles contract
  • dup: when SL valves close
  • — ventricles relax
38
Q

Murmur

A
  • abnormal heart sounds
  • one fairly common murmur occurs when the mitral valve fails to completely close
  • — swishing sound as the the blood backflows into the left atrium
39
Q

Cardiac Cycle

A
  1. Ventricular Filling
  2. Ventricular Systole
  3. Isovolumetric Relaxation
    - Quiescent Period
    - — total heart relaxation
    - — about half of the cardiac cycle
40
Q

Systole

A

contraction of chambers

41
Q

Diastole

A

relaxation of chambers

42
Q

Ventricular Filling

A
  • step 1 of the cardiac cycle
  • mid to late diastole
    1. blood flows passively from the atria to the ventricles
  • — SL valves are closed
    2. then, the atrial systole occurs
  • — P wave
  • — forces the remaining atrial blood into the ventricles
    3. atrial diastole occurs as the ventricles depolarize
  • — QRS complex
43
Q

Ventricular Systole

A
  • step 2 of the cardiac cycle
    1. ventricles contract
  • — AV valves are closed
  • — SL valves are forced open
  • — blood is forced into the aorta and pulmonary trunk
  • — pressure in the aorta generally reaches 120mmHg
  • atria are filling as the ventricles contract
44
Q

Isovolumetric Relaxation

A
  • step 3 of the cardiac cycle
  • early diastole
    1. following ventricular repolarization, the ventricles relax
    2. pressure in the aorta and pulmonary trunk causes a backflow resulting in the closure of the SL valves
    3. atria started filling while the ventricles contracted
  • — when the blood pressure in the atria exceeds that in the ventricles ( the ventricles are relaxed and got rid of their blood), the AV valves are forced open
45
Q

Cardiac Output

A
  • amount of blood pumped by each ventricle in one minute
  • calculated by multiplying the heart rate (number of beats per minute) times the stroke volume (the volume of blood pumped out by one ventricle with each beat
  • varies considerably in response to the oxygen demands of the body
46
Q

Extrinsic Factors which regulate heart rate

in addition to the intrinsic conduction system

A
  • autonomic nervous system
  • hormones
  • — epinephrine and thyroxine
  • — increase heart rate
  • imbalance in ion concentrations
  • age, body temp, gender, exercise
47
Q

Autonomic Nervous System Regulates Heart Rate

A
  • parasympathetic: decrease heart rate
  • sympathetic: increase heart rate
  • — release norepinephrine
  • — enhance Ca2+ entry into contractile cells
  • under resting conditions, both division of the ANS send impulses to the SA node
  • — this usually inhibits the heart rate
48
Q

Imbalance in Ion concentrations affect heart rate

A
  • the relationship between intracellular and extracellular ions must be maintained in a certain balance
  • hypocalcemia decreases heart rate
  • hypercalcemia may result in too many contractions
  • Too much Na+ and K+ may interfere with the transport of Ca2+ into the cardiac muscle cells
  • the mode of action of many cardiac drugs involves the transport of calcium into cardiac cells
49
Q

Disorders:

  1. Tachycardia
  2. Bradycardia
A
  1. abnormally elevated heart rate
    - — usually > 100 bpm
  2. abnormally depressed heart rate
    - — usually
50
Q

Congestive Heart Failure

A
  • cardiac output is not enough to meet tissue needs
  • damage to the myocardium may be done by coronary atherosclerosis, chronic hypertension, and multiple myocardial infarcts
51
Q

If the left side of heart fails…

A
  • pulmonary congestion
  • the right side continues to pump to the lungs –>
    but the blood can’t properly enter and exit the left side on the way back from the lungs –>
    so everything is backed up as it waits (congestion) –>
    lung tissue may become engorged –>
    forcing circulation fluid into the lung tissue –>
    causing a pulmonary edema
  • diuretics are often given to treat edema
52
Q

If the right side of the heart fails…

A
  • results in edema in the extremities
  • blood cannot properly enter and exit the right side as it comes back from the body –> everything comes backed up as it waits (congestion) –> fluid is absorbed into the body tissue because it has to go somewhere –> edema of the extremities
  • diuretics are often given to treat edema

A and P II Exams (4 decks)

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