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Emrg 1230 > Week 1- The Heart- Cardiovascular System > Flashcards

Week 1- The Heart- Cardiovascular System Flashcards

1
Q

What is the size and form of the heart?

A
  • roughly the size of a closed fist
  • 4 chambered muscular organ
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2
Q

Where is the heart located?

A
  • Located in the thoracic cavity between the lungs
  • Superior to the diaphragm and retrosternal
  • Posteriorly it rests against the 5th to the 8th thoracic vertebrae
  • Located approx. at the 2nd through 6th ribs
  • Apex (bottom) lies on the diaphragm
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3
Q

What are the functions of the heart?

A
  • Generating blood pressure
  • Routing of blood through the pulmonary and systemic circulatory routes
  • Ensuring one way blood flow with a valve system
  • Regulating blood supply to meet metabolic needs
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4
Q

Is the right side of the heart low or high pressure?

A
  • right side is a low-pressure pump
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5
Q

Is the left side of the heart low or high pressure?

A
  • left side is a high pressure pump
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6
Q

What are the two sets of tubing?

A
  • systemic circulation
  • pulmonary circulation
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7
Q

What is the pericardial cavity?

A
  • space filled with fluid (approx 10-15 mls)
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8
Q

What is the pericardial sac?

A
  • double layered closed sac that surrounds and anchors the heart
  • Loose fitting, inextensible
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9
Q

Pericardium outer layer

A
  • tough fibrous layer attached to the diaphragm, inner surfaces of the sternum and vertebral column
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10
Q

Pericardium Inner Layer

A
  • thin outer layer of the heart wall
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11
Q

What is the serous membranes?

A
  • secrete fluid to, lubricate the membranes to reduce friction during contraction
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12
Q

What are the major structures of the heart?

A
  • Atria and ventricles
  • Valves (pulmonary, aortic, bicuspid, tricuspid)
  • Vessels (aorta, pulmonary arteries and veins, superior and inferior vena cava)
  • Chordae tendineae, papillary muscles
  • Interventricular septum
  • Right & left atria, right & left ventricles
  • Septum
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13
Q

Atria

A
  • 2 superior chambers, R & L
  • Receive the blood from the veins
  • Walls are relatively thin
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14
Q

Why are atria walls thinner?

A
  • b/c they don’t need to generate much impulses as they are only moving blood a small distance to the ventricles
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15
Q

Ventricles

A
  • 2 lower chambers of the heart
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16
Q

Why are ventricle walls thicker?

A
  • b/c they are considered to be the primary “pumping chambers” as they are responsible to pump the blood out of the heart
  • Left ventricle is thicker than the right as it is responsible to push blood to the entire body
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17
Q

What are the 3 layers of the heart wall?

A
  • Endocardium
  • Myocardium
  • Epicardium
  • Pericardium surrounds all layers and encloses the coronary vessels
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18
Q

What is the Epicardium?

A
  • Visceral pericardium
  • Outer layer of the heart
  • Thin membrane attached to the outer surface of the myocardium
  • Blood vessels that nourish the heart are inside the pericardium
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19
Q

What is myocardium?

A
  • Sandwiched between 2 layers of membranes (middle layer)
  • Thickest wall of the heart
  • Contraction of the myocardium provides the force that pumps the blood through the blood vessels attached to the heart
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20
Q

What are the heart valves?

A
  • Allow blood flow in one direction
  • AV valves
  • Semilunar
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21
Q

Atrioventricular Valves

A
  • formed of fibrous connective tissues
  • 2 AV valves- mitral (bicuspid) and the tricuspid
  • Allows blood from the atrium to the ventricles but not back
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22
Q

Tricuspid

A
  • right side, 3 cusps of tissue from the fibrous tissues that separate the atria and ventricles
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23
Q

AV Valves

A
  • Strands of tissues- called the Chordae Tendineae- extend from the cusps to the papillary muscles (located in the walls of the ventricles)
  • Prevent the valves from being forced into the atria during ventricular contraction
  • They are just the right length to allow the cusps to close and seal tightly
24
Q

Semilunar valves

A
  • In the bases of the large arteries that carry blood from the ventricles
  • Pulmonary and Aortic semilunar valves
  • 3 pocket-like cusps (half moon shaped)
  • Allow blood to exit the ventricles and prevent blood flow back into the ventricles
25
Q

Pulmonary

A
  • at the opening b/t the R ventricle and the pulmonary trunk
26
Q

Aortic semilunar valves

A
  • at the opening b/t the left ventricle and the aorta
27
Q

Coronary Blood Supply

A
  • 2 major arteries- the right and the left coronary arteries
  • These branch directly off the aorta immediately above the aortic valve
28
Q

Left coronary artery

A
  • originates at the left cusp of the aortic valve
  • divide into left anterior descending artery (anterior interventricular)
  • Supplies 65-75% of the blood supply to the Left ventricle and septum
  • Oxygenation and nourishment to the myocardial cells
29
Q

Right coronary artery

A
  • Originate at the right cusp of the aortic valve
  • Divides into the right marginal artery and posterior interventricular artery
  • Supplies 25-35% of the blood supply to the left ventricle and all of the right ventricle
30
Q

Cardiac Veins

A
  • Refer to the veins that drain the blood supply of the heart wall
  • Collect the deoxygenated and metabolic waste rich blood from the capillary beds
  • The venules then join together to form the veins
31
Q

How is blood supplied to the heart?

A
  • Blood passes through to capillary beds in the myocardium and then drains via the cardiac veins
  • Empty in to the coronary sinus in the right atrium- (collection of small veins that form this larger vessel)
  • Right Coronary Vein- anterior
  • Middle and posterior cardiac veins
  • Small cardiac vein around the RA
32
Q

Heart Veins

A
  • The heart veins collect deoxygenated blood containing metabolic waste from the myocardium
  • Return it to the right atrium via the coronary sinus
33
Q

Cardiac Cycle

A
  • Contraction and relaxation phases of the heart
  • Contraction= systole
  • Relaxation= diastole
  • Atria and ventricles contract alternately, both relax between beats
34
Q

Cardiac Cycle- Broken down

A
  1. Blood enters the heart via the vena cava, enters into the right atrium
  2. Goes through tricuspid valve into the right ventricle
  3. The deoxygenated blood then leaves the heart through the pulmonary artery
  4. Blood then goes to the lungs to get oxygenated
  5. Back into the pulmonary veins- towards the heart
  6. Into the left atrium (oxygenated now)
  7. Through the mitral valve
  8. Into the left ventricle
  9. Out the aorta and to the body/organs
35
Q

Heart sounds

A
  1. sounds (“lubb-dupp”) produced by the vibrations from the closing of the heart valves
  2. 1st- AV valves- beginning of ventricular systole causes a low “lubb” sound
  3. 2nd- semilunar valves closing with ventricular diastole- “dupp” sound
  • Defective valves that leak or do not open completely cause unusual turbulence in the blood flow, resulting in abnormal sounds often called murmurs
36
Q

Regulation of the heart rate- Autonomic

A
  • Autonomic Regulation from the cardiac center in the medulla of the brain
37
Q

How do baroreceptors in the walls of the aorta and internal cartoid arteries work?

A
  • in blood pressure and alert the cardiac center
  • Then responds through stimulation of the sympathetic nervous system (SNS) or parasympathetic nervous system (PNS)
38
Q

Cardiac Center

A
  • SNS innervation causes an increase in HR (tachycardia) and contractility
  • PNS innervation causes a decrease in HR (bradycardia) and contractility (vagus nerve stimulation)
  • Constantly changes to meet the needs of the body cells
39
Q

Sympathetic Innervation

A
  • From the cardiac center- spinal cord to the SA node, AV node and portions of the myocardium
40
Q

Where is epi and nonepi secreted?

A
  • Secreted at the synapses in the heart - increase the rate and strength of the contraction
  • this in turn stimulate beta receptors and increased HR and contractility
41
Q

What factors increase HR?

A
  1. Elevated body temp
  2. Increased environmental temp
  3. Exercise
  4. Smoking
  5. Stress
42
Q

Parasympathetic Innervation

A
  • Cardiac center to the vagus nerve to innervate the SA and AV nodes through the right and left vagus nerves
  • Acetylcholine is secreted at the synpases- slows the rate (acts on muscarinic and nicotinic cholinergic receptors)
  • The greater the frequency of impulses the slower the rate
43
Q

What other factors affect heart rate?

A
  • Age, sex, physical condition, temperature, blood levels K+ and CA++ ions
  • HR declines with age
  • Faster in females
  • Slower with good conditioning
  • Increase with temperatures
  • Increased CA++ increases with HR and prolongs contraction
  • Excessive K+ (hyperkalemia) decreases HR and contraction, low K+- lethal rhythms
44
Q

Cardiac Muscle Cells

A
  • Cardiocytes (myocardiocytes)
  • Heart muscle cells build to form involuntary striated muscle strands
  • Highly resistant to fatigue due to high level of mitochondria
  • Break down nutrients into cell energy
45
Q

Cardiac Cells

A
  • Intercalated discs synchronize the contractions of all cardio myocytes
  • Unique to cardiac muscle, found where cells join end to end (allow all the cells to function as a single organ)
  • Contribute to the superiority of conductivity
  • These disks regulate the passage of positive and negative electrons
  • Allows electrical current to spread rapidly throughout the myocardium
46
Q

As a result action potentials travel from cell to cell without delay

A
  • Contain actin and myosin (protein filaments) for contraction capabilities
  • Muscle contraction occurs when these filaments slide over one another repetitively
  • Myofibrils lock together with other cells and increase their effciency
  • Because they are mechanically, chemically and electrically connected they act as a single cell (functional syncytium)
47
Q

Contractile Cells

A
  • Mitochondria produce ATP
  • ATP provides the energy for contraction but needs O2
  • There is no significant oxygen debt like in the skeletal muscles (eg. no deprivation like in muscle cells when working out)
  • Cardiac muscle cells are limited to about 200 contractions/ min
  • Tetany- contracted muscles building on one another to sustain the contraction
  • B/c of the refractory period, this is not possible in cardiac muscles
48
Q

What are the properties of Cardiac Cells?

A
  • Contractility
  • Automaticity
  • Rhythmicity
  • Conductivity
  • Refractory period
49
Q

What is contractility?

A
  • ability to respond to an impulse by contracting
50
Q

What is automaticity?

A
  • ability to generate their own impulses
51
Q

What is rhythmicity?

A
  • regular impulse generation
52
Q

What is conductivity?

A
  • ability to transmit impulses to adjacent cells
53
Q

What is refractory period?

A
  • relaxation without response to another simulation
54
Q

What is cardiac output?

A
  • CO is the volume of blood ejected by a ventricle in one min and depends on the HR and SV (CO= HR x SV)
  • SV is the volume pumped from one ventricle in one contraction
  • This means that the heart pumps an amount equal to the body’s total blood volume each minute
55
Q

What is stroke volume?

A
  • Varies with sympathetic simulation and venous return
  • When an increased amount of blood returns to the heart (exercise), the heart is stretched more, and the force of contracting increases
  • During stress, exercise or infection- CO increases

Emrg 1230 (24 decks)

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