Lecture 4: Heart Structure & Function Flashcards

1
Q

Where will pressure in cardio system be the highest?

A

when ventricles contract in aorta during systole

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2
Q

What are the 2 layers pericardium?

A
  • parietal -> fibrous & attaches to diaphragm
  • visceral -> fuses to surface of the heart
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3
Q

What is the space between the visceral & parietal pericardium called?

A

pericardial cavity -> filled with fluid to lubricate

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4
Q

Where does the heart lie?

A

in the pericardium

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5
Q

Which pericardium forms the outer epicardium?

A

visceral pericardium

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6
Q

What are the 3 layers of the heart?

A
  • epicardium -> outer layer with blood vessels
  • myocardium -> muscle layer in the middle
  • endocardium -> thin epithelium & connective tissue on the inside
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7
Q

How is the heart formed?

A
  • from mesoderm as 2 cardiogenic cords
  • single heart tube formed by lumen
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8
Q

How does blood enter & exit the heart?

A
  • enters posteriorly
  • exits anteriorly
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9
Q

What is the sinus venosus?

A

accepts blood into the heart

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10
Q

Where does the blood go once into the heart?

A
  1. accepted into heart by sinus venosus
  2. sinoatrial valve to atrium
  3. atrioventricular valve to ventricle
  4. ventricles send blood into bulbus cordis
  5. exits bulbus & enters truncus arteriosus
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11
Q

The sinus venosus becomes what of the right atrium?

A

SA node

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12
Q

What are the changes in structures within the heart?

A
  • atrium -> left & right atria
  • ventricle -> left ventricle
  • bulbus cordis -> right ventricle
  • truncus -> ascending aorta & pulmonary trunk
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13
Q

How does deoxygenated blood enter the heart?

A

through vena cava - > right atrium -> tricuspid valve

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14
Q

How is the tricuspid valve held to the ventricular wall?

A

chordae tendineae

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15
Q

How is the tricuspid valve anchored?

A

by papillary muscles

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16
Q

How does oxygenated blod enter the left atrium?

A

enters via pulmonary veins from lungs

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17
Q

The left atrium has what cusps?

A

bicuspid/ mitral valve

18
Q

Actin & myosin are organized into what?

A

sarcomeres

19
Q

Cardiac muscle is composed of what cells?

A

uninucleate branched cells

20
Q

Intercalated discs are composed of what 2 things?

A
  • gap junctions -> allow Ca2+ to pass b/w cells for contractions
  • desmosomes -> keep cells tight together
21
Q

What is the heart chambers cycle?

A
  1. relaxation of empty ventricles
  2. opens mitral & tricuspid valves to pull blood in
  3. atria contract to force blood into ventricles
22
Q

What occurs when the mitral & tricuspid valves are closed?

A
  1. ventricles contract
  2. aortic & pulmonary valves open & blood leaves
  3. atrial relaxation allows blood to fill
  4. negative pressure of pericardium
  5. all 4 chambers relax
23
Q

What do the 1st & 2nd sound mean with a heartbeat?

A
  • 1st sound -> mitral & tricuspid closing / ventricle contracts
  • 2nd sound -> pulmonary & aortic closing / ventricle relaxation
24
Q

What node acts as a pacemaker for the heart?

A

sinoatrial node

25
Q

What occurs as electrical signals travel via intercalated discs?

A
  • rhythmic contraction of chambers
  • depolarization sends signals through cardiac conducting tarcts
26
Q

How is the contraction of the atria triggered?

A
  • Bachman’s bundle sends signal to left atrium
  • tracts within right atrium trigger contraction
27
Q

What happens when non-conductive tissue blocks the way?

A

signals cannot pass to ventricles

28
Q

The electrical signal in the heart takes 50 milliseconds to reach where?

A

AV node

29
Q

The AV bundle is also known as what?

A

Bundle of His

30
Q

What is the path of electrical activity in the heart?

A

SA node -> right & left (Bachman’s bundle ) atrium -> AV node -> AV bundle/Bundle of His -> right & left ventricle

31
Q

What does the depolarization of cardiac cells rely on?

A

Na+ & Ca2+

32
Q

How do cardiac cells become depolarized?

A
  • resting membrane potential is unstable; only -60mV
  • K+ channels open at +5mV
33
Q

What nerves regulate the SA node?

A

vagus & sympathetic nerves

34
Q

What glands regulate the SA node?

A

thyroid (T3 & t4) & adrenal (norepeinephrine & epinephrine)

35
Q

What happens during the plateau of contractile cells?

A
  1. as Na+ close, Ca2+ & K+ channels open
  2. Ca2+ moves in slowly while K+ moves out
  3. creates refractory period
36
Q

What does the PR interval represent?

A
  • depolarization of SA node
  • how long it takes for impulse to reach AV node
37
Q

What does the QRS interval represent?

A

depolarization of ventricle

38
Q

What does the T wave represent?

A

repolarization of ventricle

39
Q

What does the P wave represent?

A

depolarization of atria

40
Q

What does the QRS complex represent?

A

depolarization of ventricles