Cardiovascular System 1 - The Heart Flashcards

1
Q

What is the primary germ layer that the heart is derived from?

A

Mesoderm

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2
Q

Briefly describe the embryological development of the heart?
(Day 21 & 22)

A

Day 21:
Two heart tubes form from the mesoderm and then fuse to form a single primitive heart tube.

Day 22:
The primitive heart begins to beat and begins to bend and fold on itself.

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3
Q

Briefly describe the embryological development of the heart?
(Day 28 & 43)

A

Day 28:
The heart tube then becomes partitioned into the four chambers of the heart and the great vessels entering and leaving the heart form.

Day 43:
Complete heart begins to be visible.

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4
Q

Where is the heart located in the thoracic cavity?

A

In a space called the mediastinum, which is the central space in the thoracic cavity between the two lungs.

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5
Q

How is the heart orientated in the mediastinum?

A

–> The heart sits on the central tendon of the diaphragm.
–> Is positioned posteriorly to the sternal body.
–> 1/3 is to the right & 2/3 is to the left of the midline.
–> Its base is positioned posterior and slightly up (located anterior to the thoracic spine).
–> Its apex points anteriorly, to the left and inferiorly (in the 5th left intercostal space).

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6
Q

Where does the heart sit?

A

The heart sits on its inferior surface which is also referred to as the diaphragmatic surface.

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7
Q

What is the pericardium and what is its function?

A

The protective sac around the heart.

Function:
To protect the heart and keep it in place with the thorax, as it is fused with the central tendon of the diaphragm.

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8
Q

What are the 2 parts of the pericardium?

A

The outer fibrous pericardium.
The inner serous pericardium.

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9
Q

What are the 3 layers of the heart wall?

A

Visceral layer of serous pericardium (epicardium)
Myocardium (middle)
Endocardium (inner)

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10
Q

Which layer of the heart wall does the visceral layer of the serous pericardium form?

A

The outer layer of the heart wall.

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11
Q

What is the epicardium composed of?

A

Outer layer = simple squamous epithelium
Inner layer = areolar connective tissue & fat.

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12
Q

What is the myocardium composed of?

A

Cardiac muscle (myo = muscle)

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13
Q

Explain the difference in the thickness of the myocardium between the left ventricle and the right ventricle?

A

The myocardium of the left ventricles is thicker than that of the right ventricles due to the higher pressure needed to pump oxygenated blood throughout the systemic circulation compared to the lower pressure required for the pulmonary circulation.

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14
Q

What is the endocardium composed of?

A

Inner layer = areolar connective tissue.
Outer layer = endothelium (simple squamous epithelium).

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15
Q

What does the pericardial cavity contain & what is its function?

A

Pericardial fluid:
Lubricates the surface of the heart as it moves within the cavity.

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16
Q

What are the 4 chambers of the heart?

A

Right atrium
Right ventricle
Left ventricle
Left atrium

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17
Q

What is the general function of the 2 atriums and 2 ventricles?

A

Two atriums = receiving chambers as they receive blood from either the lungs or the body.

Two ventricles = pumping chambers as they pump blood to either the lungs or the body.

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18
Q

What is the function of the auricle of the right atrium & the coronary sulcus?

A

Auricle of the right atrium:
Increase the capacity of the atria.

Coronary sulcus:
Supply blood to the heart itself.

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19
Q

Label the external and internal features of the heart?

A
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20
Q

Label the external and internal features of the heart?

A
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21
Q

Identify the posterior and inferior surface of the heart?

A

a) = posterior surface
b) = inferior (diaphragmatic) surface

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22
Q

Define pulmonary and systemic circulation?

A

Pulmonary circulation:
The circulation between the heart and the lungs.

Systemic circulation:
The circulation between the heart and the body.

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23
Q

What type of blood is found on each side of the heart?

A

RIght side = deoxygenated blood.
Left side = oxygenated blood.

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24
Q

What is the role of arteries and veins?

A

Arteries:
Bring blood away from the heart.

Veins:
Bring blood towards the heart.

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25
Q

What are the veins that drain deoxygenated blood into the right atrium and what are their roles?

A

Superior vena cava:
Drains deoxygenated blood into the right atrium from all structures above the diaphragm, except the heart itself.

Inferior vena cava:
Drains deoxygenated blood into the right atrium from the heart itself.

Coronary sinus:
Drains deoxygenated blood into the right atrium from all structures below the diaphragm.

26
Q

Label the veins inserting into the right atrium?

A
27
Q

Label the remaining internal features of the right atrium and explain their role?

A

Fossa ovalis:
When a baby is born, foramen ovale closes off, leaving the fossa ovalis.
Foramen ovale allows blood to pass directly from the right atrium into the left atrium in order to bypass the non-functioning foetal lungs.

Interatrial septum:
This is the partition separating the right and left atria.

Pectinate muscles:
The exact function of the pectinate muscles is unknown, but it is thought that they assist with the shunting of blood from the right atrium into the left atrium through foramen ovale during foetal life.

28
Q

Explain the movement of deoxygenated blood from the right atrium to the right ventricle?

A

From the right atrium, deoxygenated blood flows into the right ventricle through an opening called the right atrioventricular orifice.

29
Q

Label the parts of the right ventricle?

Explain the function of the trabeculae carneae, interventricular septum & right atrioventricular valve?

A

Trabeculae Carneae:
Unknown function

Interventricular Septum:
Separates the right and left ventricles.

Right Atrioventricular Valve:
Guards the right atrioventricular orifice (aka the tricuspid valve).

30
Q

Explain the function of the chordae tendineae & papillary muscles?

A

Chordae Tendineae:
Connect the cusps of the right atrioventricular valve to muscles in the right ventricle called papillary muscles.

Papillary Muscles:
Anchors the cusps of the right atrioventricular valve to the ventricular wall via the chordae tendineae.

31
Q

What part of the heart pumps deoxygenated blood from the right ventricle to the lungs to be oxygenated?

A

Pulmonary trunk (artery).

32
Q

Label the parts of the right ventricle?

A
33
Q

Explain the function of the pulmonary semilunar valve?

A

Pulmonary Semilunar Valve:
Guards the entrance to the pulmonary trunk.

34
Q

Explain the function of the ligamentum arteriosum & its original part?

A

Ligamentum Arteriosum:
An embryological remnant of the ductus arteriosus (a channel that connects the pulmonary trunk to the aorta during foetal life).
Ductus arteriosus: Allows blood to pass directly from the pulmonary trunk into the aorta in order to bypass the non-functioning foetal lungs.

35
Q

Which chamber of the heart does oxygenated blood from the lungs return to?

A

Left atrium of the heart.

36
Q

How many veins drain oxygenated blood from the lungs to the heart and what are their names?

A

2 Left pulmonary veins
2 Right pulmonary veins

37
Q

Label the parts of the left atrium?

A
38
Q

When oxygenated blood is travelling from the left atrium to the left ventricle, what does it need to pass through?

A

The left atrioventricular orifice

39
Q

What guards the left atrioventricular orifice opening & what are its other names?

A

Left atrioventricular valve

Also called the bicuspid valve or mitral valve.

40
Q

How many papillary muscles are located in the left and right ventricles?

A

Left ventricle = 2 (left atrioventricular valve has 2 cusps).
Right ventricle = 3

41
Q

What artery does oxygenated blood travel through when being transported from the left ventricle to the rest of the body?

A

The aorta (the largest artery in the body)

42
Q

What guards the entrance to the aorta?

A

Aortic semilunar valve

43
Q

What is a special feature about the left ventricle?

A

It has the thickest wall of the four heart chambers, as it needs to generate enough pressure to be able to pump blood to the entire body.

44
Q

Label the parts associated with the left ventricle?

A
45
Q

What is commonly misunderstood about the cardiac cycle?

A

That all 4 chambers work simultaneously with one another.

46
Q

What is the cardiac cycle?

A

The cycle of heart filling and heart pumping that occur over one heartbeat.

47
Q

Define ventricular systole & ventricular diastole?

A

Ventricular systole:
The pumping of blood from the ventricles (when the ventricles are contracting).

Ventricular diastole:
The filling of the ventricles with blood occurs (when the ventricles are relaxing).

48
Q

What is important about the heart valves?

A
  1. The opening and closing of the heart valves is mediated by pressure differences.
  2. The four heart valves are never all open or all closed at the same time.
49
Q

Label the valves of the heart?

A
50
Q

What is the function of the atrioventricular & semilunar valves?

A

Atrioventricular valves:
To prevent the backflow of blood from the ventricles into the atria when the ventricles contract.

Semilunar valves:
To prevent the backflow of blood from the pulmonary trunk and aorta into the ventricles when the ventricles relax.

51
Q

Explain the process of atrioventricular valves closed & opened?

A

Closed:
When the ventricle contracts (ventricular systole) and the pressure inside the ventricles becomes greater than the pressure inside the atria, the atrioventricular valves close due to blood pushing up on the valve cusps.

Open:
When the ventricles relax (ventricular diastole) and the pressure inside the atria becomes greater than the pressure inside the ventricles, the atrioventricular valves open to allow blood to flow passively from the atria into the ventricles.

52
Q

Explain the process of semilunar valves closed & opened?

A

Closed:
When the ventricles relax (ventricular diastole) and the pressure inside the pulmonary trunk and aorta becomes greater than the pressure inside the ventricles, the semilunar valves close due to blood pushing back on the valve cusps and filling them with blood.

Open:
When the ventricles contract (ventricular systole) and the pressure inside the ventricles becomes greater than the pressure inside the pulmonary trunk and aorta, the semilunar valves open to allow blood to enter the pulmonary trunk and aorta from the ventricles.

53
Q

Where is the fibrous skeleton of the heart located?

A

Between the atria and the ventricles.

54
Q

What is the structure of the fibrous skeleton of the heart?

A

Consists of four fibrous rings that encircle the four heart valves.

55
Q

What are the functions of the fibrous skeleton of the heart?

A
  1. Anchors the cusps of the heart valves.
  2. Provides a framework for the attachment of cardiac muscle tissue.
  3. Acts as an electrical insulator between the atria and the ventricles.
56
Q

What stimulates the heart to contract?

A

The cardiac conduction system of the autonomic nervous system.

57
Q

Label the components of the cardiac conduction system?

A
58
Q

Explain the function of the sinoatrial (SA) node?

A

It is the pacemaker of the heart, as it sets the intrinsic rhythm of the heartbeat.
It initiates cardiac excitation by generating an electrical impulse that is conducted through both atria.

59
Q

Explain the function of the atrioventricular (AV) node & atrioventricular (AV) bundle?

A

Atrioventricular (AV) node:
It receives the electrical impulse from the SA node and slows its conduction, allowing time for the atria to contract and empty their remaining blood into the ventricles before the ventricles are stimulated to contract.

Atrioventricular (AV) bundle:
Is the only point where the electrical impulse can be conducted from the atria to the ventricles.

60
Q

Explain the function of the right and left bundle branches & purkinje fibers?

A

Right and left bundle branches:
These are the branches of the AV bundle and they course through the interventricular septum towards the apex of the heart.

Purkinje fibers:
These spread throughout the walls of the ventricles and conduct the electrical impulse through the ventricles.

61
Q

REVISION: Order the 6 steps in the flow of blood throughout the heart?

A