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Phys > cardio > Flashcards

cardio Flashcards

1
Q

The cardiovascular system transports materials throughout the body

A

– From external environment: nutrients, water, and gases
– Materials between cells: hormones, immune cells, antibodies

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2
Q

Waste eliminated by cells:

A
  • CO2, heat, metabolic waste
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3
Q

blood vessels

A
  • arteries: away from heart. mainly oxygenated
  • veins: towards the heart. mainly deoxygenated
  • capillaries
  • portal system joins two capillary beds in series
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4
Q

heart

A

– Septum divides heart into two halves (left and right)
– Atrium receives blood returning to heart
– Ventricle pumps blood out of heart

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5
Q

blood

A

cells and plasma

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6
Q

pulmonary arteries

A
  • only artery that carries deoxygenated blood
  • carries blood from heart to lungs
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7
Q

pulmonary veins

A
  • carries oxygenated blood from lungs to left atrium
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8
Q

aorta

A
  • biggest artery
  • highest pressure
  • lot of force and pressure bc it is right next to the heart
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9
Q

inferior and superior vena cava

A
  • inferior = below
  • superior = above
  • attach to right atrium
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10
Q

pulmonary circuit

A
  • right side of the heart
  • pump blood to lungs
  • deoxygenated
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11
Q

systemic circuit

A
  • left side of heart
  • pump blood to the rest of the body
  • oxygenated
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12
Q

4 chambers of the heart

A
  • 2 atrium – pump blood to ventricles
    • thin walled upper chambers
  • 2 ventricles
    • thick walled lower chambers
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13
Q

atrioventricular valves

A

– Between atria and ventricles
– Chordae tendineae prevent eversion during ventricular contraction
▪ Attached to valve flaps from papillary muscles
– Tricuspid valve on the right side
– Bicuspid valve (mitral valve), on the left side

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14
Q

semilunar valves

A

– Between ventricles and arteries
– Aortic valve
– Pulmonary valve

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15
Q

The coronary circulation supplies blood to the heart

A
  • Coronary arteries: carry oxygen
  • Coronary veins: carry deoxygenated
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16
Q

pericardium

A
  • CT sac that surrounds the heart
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17
Q

pericardial fluid

A
  • pericardium sits in this
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18
Q

How blood travels

A

– Aorta and pulmonary trunk carry blood from heart
– Vena cava and pulmonary veins return blood to heart
– Deoxygenated: vena cava → right atrium → right ventricle → pulmonary trunk
– Oxygenated: pulmonary veins → left atrium → left ventricle → aorta

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19
Q

autorhythmic cells (pacemakers)

A

– Signal for contraction
– Smaller and fewer contractile fibers compared to contractile cells
– Do not have organized sarcomeres
- function without the CNS
- generate own action potentials

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20
Q

contractile cells

A

– Striated fibers organized into sarcomeres
- actual myocardial cells that actually contract as the action potential moves thru the intercalated disks

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21
Q

cardiac muscle

A
  1. Smaller and have single nucleus per fiber
  2. Branch and join neighboring cells through intercalated disks
  3. Gap junctions
  4. T-tubules are larger and branch
  5. Sarcoplasmic reticulum is smaller
  6. Mitochondria occupy one-third of cell volume – more in cardiac bc we need more ATP. heart never gets tired –> needs constant ATP
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22
Q

Waves of the ECG

A

– Three waves
▪ P wave: depolarization (contraction) of the atria – always from SA node
▪ QRS complex: wave of ventricular depolarization (contraction)
- more force from ventricles bc we have to push blood farther
–Atrial repolarization (relaxation) is part of QRS (can’t see this bc of the magnitude of the QRS
▪ T wave: repolarization (relaxation) of the ventricle
– Two segments
▪ P-R segment: AV nodal delay – time AV node is holding on to action potential (contraction)
▪ S-T segment: ventricular and atrial relaxation
- higher = heart attack and lower = HAD a heart attack

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23
Q

electrical events of the cardiac cycle

A
  • Mechanical events lag behind electrical events: contraction follows action potential
  • ECG begins with atrial depolarization, atrial contraction at the end of P wave
  • P-R segment electrical signal goes through AV node and AV bundle
  • Q wave end: ventricular contraction begins and continues through T wave
24
Q

conducting system of the heart – how action potentials spread thru cardiac muscles

A
  1. SA node fires action potential and atria depolarizes (contracts)
  2. Electrical signal goes to AV node
  3. AV holds on to action potential (slows down conduction)
  4. Once it knows blood is all out of the atria, AV node sends off the action potential thru bundle of his to contract ventricles
25
Q

purkinje fibers

A
  • transmit electric signals down the atrioventricular bundle (AV bundle or bundle of His) to left and right bundle branches.
26
Q

SA node, AV node, Purkinje fibers

A
  • SA node sets the pace of the heartbeat at 70 bpm
    – AV node (50 bpm) and Purkinje fibers (25–40 bpm) can act as pacemakers under some conditions
    – AV node delay with slower conductional signals through nodal cells
27
Q

what do electrical signals coordinate?

A
  • contraction
28
Q

Internodal pathway from sinoatrial node (SA node) to atrioventricular node (AV node)

A

– Routes the direction of electrical signals so the heart contracts from apex to base

29
Q

SA node

A
  • depolarization begins here
  • autorhythmic cells in the right atrium that serve as the main pacemaker of the heart
30
Q

AV node

A
  • group of autorhythmic cells near the floor of the right atrium
  • connected to SA node by internodal pathway
31
Q

left and right bundle branches

A
  • continue downward to the apex of the heart, where they divide into smaller Purkinje fibers that spread outward among the contractile cells.
32
Q

apex

A
  • heart angles down to the body while the broader base lies just behind the breastbone or sternum
33
Q

base

A
  • top of heart
34
Q

septum

A
  • heart muscle btw ventricles to keep them separate
35
Q

thoracic cavity

A
  • behind sternum and protected by ribs –> above diaphragm
  • heart is on the ventral side of the thoracic cavity
  • contains hearts and lungs
  • heart is sandwiched btw the lungs
36
Q

3 layers of the heart

A
  • epicardium: outer layer
  • myocardium: cardiac muscle
  • endocardium: inner lining
37
Q

stroke volume

A
  • SV = EDV-ESV –> volume of blood before contraction minus volume of blood after contraction
  • amount of blood ejected with each contraction (stroke) –> average = 70 mL
38
Q

cardiac output

A
  • the amount of blood pumped out of the heart each minuted (CO = HR x SV)
  • Normal adult CO = 5 L/min
39
Q

Ejection Fraction

A
  • percentage of blood volume (EDV) ejected from ventricles per stroke
  • normal = 60-70% of volume –> ventricles pump out this much blood
  • less than 40% indicates significant impairment
40
Q

Cardiac Entry is a Feature of Cardiac EC Coupling

A
  • Action potential starts with the heart pacemaker cells
  • Ca2+ induced Ca2+ release
    – Voltage-gated L-type Ca2+ channels in the cell membrane open
    – Ryanodine receptors (RyR) open in the sarcoplasmic reticulum (SR) open in response to inflow of
    ▪ Called spark Ca2+
    – Summed sparks Ca2+ create a signal
  • Calcium binds to troponin
  • Crossbridge cycle as in skeletal muscle
  • Relaxation calcium removed from cytoplasm
    – Into the SR with Ca2+-ATPase
    – Out of cell through the Na+-Ca2+ exchanger (NCX)
41
Q

Explain how cardiac muscles contract

A
  • electrical signal thru the action potential contracts the heart cells thru the intercalated disks
42
Q

tetanus

A
  • sustained heart contraction
43
Q

how are action potentials in cardiac muscle and pacemaker cells different than action potentials in neurons?

A
  • neurons = get action potentials from brain
  • cardiac = generate own action potentials thru pacemaker cells
44
Q

understand why a longer action potential is required for a cardiac muscle cell

A
  • longer bc of Ca2+ inflow
    • Ca2+ keeps it at a higher membrane potential (more positive)
  • need longer muscle contraction so we don’t get into tetanus
  • tetanus: constant state of contraction. heart beat would overlap and there would be no rest period
45
Q

diastole

A
  • cardiac muscle relaxes
  • pressure of ventricles produce when they relax
46
Q

systole

A
  • cardiac muscle contracts
  • pressure of ventricles produce when they contract
47
Q

phase 1 of cardiac cycle

A
  1. The heart at rest: atrial and ventricular diastole
    ▪ The atria are filling with blood from the vein bc its relaxed
    ▪ AV valves open –> ventricles fill
48
Q

phase 2 of cardiac cycle

A
  1. Completion of ventricular filling: atrial systole
    ▪ Atria contract
    ▪ Last 20% of blood volume driven to ventricles
    ▪ End-diastolic volume (EDV): volume in ventricle at the end of ventricular relaxation
49
Q

phase 3 of cardiac cycle

A
  1. Early ventricular contraction and the first heart sound
    ▪ AV valves close
    –Vibrations following closure of the AV valves
    –“Lub” (closure of AV valves)
    ▪ No blood in or out (isovolumic ventricular contraction)
    ▪ Increasing pressure due to ventricular muscle contraction
    ▪ Concurrent atrial diastole
    –Atria relax and blood flows in the atria
50
Q

phase 4 of cardiac cycle

A

▪ Semilunar valves open (aortic (goes into aorta) and pulmonic (pulm artery))
▪ Blood is ejected into arteries
▪ End-systolic volume (ESV): volume in ventricle at the end of ventricular contraction

51
Q

phase 5 of cardiac cycle

A
  1. Ventricular relaxation and the second heart sound
    ▪ Arterial blood flows back towards heart
    –Semilunar valves shut –> second heart sound
    –“Dup”
    ▪ Ventricular muscles relax pressure drops (still higher than atrial pressure)
    ▪ No blood enters or exits (isovolumic ventricular relaxation)
    ▪ AV valves open when ventricular pressure drops below atrial pressure
52
Q

how many cardiac cycles does a pressure-volume curve represent?

A
  • one
53
Q

preload

A
  • degree of stretch
54
Q

afterload

A
  • combined load of EDV and arterial resistance during ventricular contraction
55
Q

contractility

A
  • intrinsic ability of a cardiac muscle fiber to contract at any given fiber
56
Q

heart rate

A
  • time btw two P waves and two Q waves
  • parasym = decreases it via vagus nerve
  • symp = increases it

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