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Anatomy and Physiology Flashcards

(41 cards)

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1
Q

What is the heart enclosed in?

A

Thoracic Cavity (mediastinum)

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2
Q

What are the two Atrioventricular Values

A

Mitral Valve and Tricuspid Valve

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3
Q

Describe the Atria?

A

Thin walled, low-pressure chambers that receive blood
Wall of connective tissue separating atria - interatrial septum
Left atrial wall thicker than right
Right atria has larger reservoir
Atria fill passively to 70% as AV valves close
Final contraction from atria completely fill ventricles

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4
Q

Describe the ventricles?

A

Ventricles are large, thick-walled, high-pressure chambers that pump blood to the lungs and through systemic circulation
The left ventricle is 3 times thicker than the right ventricle to enable forceful contraction and overcome arterial pressure and resistance
Wall of connective tissue separates ventricles - interventricular septum

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5
Q

Name and describe the layers of the walls of the atria and ventricles?

A

Walls are composed of three layers of tissue

Innermost layer: Endocardium - smooth to promote low friction movement of blood

Middle Layer: Myocardium - contains muscle cells

Outer layer: Epicardium - thin layer of smooth connective tissue

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6
Q

Describe the endocardium

A

Inner layer of the heart wall
Smooth to promote low friction movement of blood
Depolarization of heart goes from Endo- to Epi-
Repolarization of heart goes from Epi- to Endo-

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7
Q

Describe the myocardium?

A

Middle layer of heart wall
Muscle responsible for contraction of heart
Large walls
Needs oxygenated blood for contraction

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8
Q

Describe the epicardium?

A

Outer layer of heart wall and muscle tissue
Also the inner layer of the pericardium (also known as visceral pericardium)
Mainly connective tissues and functions as protection

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9
Q

Describe the pericardium?

A

The heart is enclosed in the pericardium, which is a fibrous, doubled-walled sac consisting of two layers. The outer tough layer - fibrous pericardium, which comes into direct contact with the lung and the inner layer of the pericardium, which is called the serous pericardium.
The visceral pericardium (epicardium) covers the heart itself.

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10
Q

Describe the function of the heart valves?

A

Ensure unidirectional blood flow (no ack flow)

Opens and Closes depending on pressure difference on each side of the valve

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11
Q

What are the main valves?

A

Atrioventricular Valves (AV)

  • Prevent backflow of blood from ventricles to atria during systole
  • Complex structure (leaflets, chordae tenindae & papillary muscles)
  • Anchored to wall of ventricle by chordae tendinae, which prevents them from inverting
  • AV valves consist of the Tricuspid and Mitral Valves

Semilunar Valves (SL)

  • Prevent backflow of blood from arteries into ventricles during diastole
  • Simple structure with passive closing: backflow of blood after systole
  • SL valves consist of the Aortic and Pulmonic Valves
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12
Q

What do the AV valves consist of?

A

AV valves consist of the Tricuspid Valve and Mitral (Bicuspid) Valve

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13
Q

What do the Semilunar valves consist of?

A

SL valves consist of the Aortic Valve and Pulmonic Valve

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14
Q

What are the veins of the heart?

A

Veins are blood vessels that bring blood back to the heart and drain blood from organs and limbs.

There are 3 veins connected to the right atrium:

  • Inferior Vena Cava (Lower Body)
  • Superior Vena Cava (Upper Body)
  • Coronary Sinus (Coronary Arteries)

There are 4 veins connected to the left atrium:
- 4 pulmonary veins (lungs)

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15
Q

Describe the function of the arteries?

A

Arteries carry blood away from the heart. The left ventricle pumps blood into the aorta and the right ventricle pumps blood into the pulmonary artery. Main arteries have elastic properties which are important in determining blood pressure.

Right Coronary Artery
 - Posterior Interventricular Artery
Left Coronary Artery
 - Circumflex Artery
 - Anterior Interventricular Artery
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16
Q

Which arteries supply blood to the muscle walls of the heart?

A

Coronary Arteries
There are two main arteries that supply blood to the muscle walls of the heart
Right Coronary Artery (RCA)
Left Coronary Artery (LCA)

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17
Q

Describe the position of the right coronary artery?

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A

Arises from the aorta just above the right aortic coronary cusp
One Main Branch that runs in the groove between the right atrium and right ventricle
Travels downward and then posteriorly in the right AV groove
Supplies blood to the right ventricle & part of the left ventricle

18
Q

Describe the position of the left coronary artery?

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A

(Also known as left main stem and all its branches)
Arises from the base of the aorta just above the left coronary cusp of the aortic valve
Left main stem is 1-25 mm long and bifurcates (splits) into left anterior descending artery (LAD) and the left circumflex (LCx)

LAD reaches the apex and supplies blood to the anterolateral myocardial and inter-ventricular septum. Branches into septals and diagonals

LCx supplies blood to the posterolateral left ventricle and the SA node (in 38%). Branches into obtuse marginal branches

19
Q

The is the role of the autonomic nervous system of the heart.

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A

The heart is innervated by both the sympathetic and parasympathetic divisions of the autonomic nervous system.
Sympathetic division utilizes the “fight/flight” response, allowing the body to respond appropriately when under stress
Parasympathetic division is responsible for conversation & restoration of the body’s resources

20
Q

What does sympathetic stimulation do to the heart?

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A

Excitatory
Increase heart rate and force of contraction
Increases excitability
Facilitates conduction in the AV node
Encourages strong coronary vasodilation & elevates blood flow

21
Q

What does the parasympathetic nervous system do to the heart?

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A

Inhibitory
Decreases heart rate and atrial contraction force
Slows rate of discharge from SA node
Inhibition of AV conduction

22
Q

Explain the mechanical events of the cardiac cycle

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A

The cardiac cycle is described as the flow of blood through the heart during one complete heartbeat: atrial systole and atrial diastole, and ventricular systole and ventricular diastole.

Systole refers to contraction periods of the heart activity and diastole refers to relaxation periods of heart activity.

23
Q

Describe cardiac output and stroke volume and its effect on the heart?

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A

Cardiac Output (Q): amount of blood pumped out by each ventricle in one minute

Stroke Volume (SV): volume of blood pumped out by a ventricle with each beat

Q = HR x SV
“Stroke volume is correlated with force of ventricular contraction”

24
Q

What is the Tricuspid Valve?

Study These Flashcards
A

Valve between Right Atrium and Right Ventricle

Prevents blood going back into atrium (systole)

25
What is the Mitral Valve?
Valve between the Left Atrium & Left Ventricle | Prevents blood going back into atrium (systole)
26
What function do the AV valves have?
- Prevent backflow of blood from ventricles to atria during systole - Complex structure (leaflets, chordae tendinae & papillary muscles) - Anchored to wall of ventricle by chordae tendinae, which prevents them from inverting - AV valves consist of the Tricuspid and Mitral Valves
27
What function do the SL valves have?
- Prevent backflow of blood from arteries into ventricles during diastole - Simple structure with passive closing: backflow of blood after systole - SL valves consist of the Aortic and Pulmonic Valves
28
Where is the Aortic Valve?
Lies between the left ventricle and aorta | 3 cusps
29
Where is the Pulmonic Valve?
Lies between the right ventricle and pulmonary artery | 3 cusps
30
What are Bundle Branches?
The bundle branches are a part of the electrical system of the heart. The electrical system controls the heartbeat and is made up of several parts that tell the ventricular muscle when to contract. The SA node starts the heartbeat, causing the atria, or upper chambers of the heart, to contract. The signal then travels through the AV node and the bundle of His and splits into the left and right bundle branches, directing the impulse to the respective left and right ventricles. The signals end at the Purkinje fibers causing the ventricles, the lower chambers of the heart, to contract. The usual flow of electrical signals produces a normal heartbeat.
31
Describe Electrical Conduction of the Heart
The electrical system controls the heartbeat and is made up of several parts that tell the ventricular muscle when to contract. The SA node starts the heartbeat, causing the atria, or upper chambers of the heart, to contract. The signal then travels through the AV node and the bundle of His and splits into the left and right bundle branches, directing the impulse to the respective left and right ventricles. The signals end at the Purkinje fibers causing the ventricles, the lower chambers of the heart, to contract. The usual flow of electrical signals produces a normal heartbeat.
32
Explain Mid-to-Late Diastole
Refers to Ventricular Filling The blood returning from the body passing through the atria and into the ventricles - pressure in the heart is low.
33
Describe the terms Systole and Diastole
Systole refers to contraction periods of the heart activity and diastole refers to relaxation periods of heart activity.
34
Explain regulation of stroke volume?
Stroke volume represents the difference between the amount of blood that collects in the ventricle during diastole (End Diastolic Volume - EDV) and the volume of blood remaining in a ventricle after it has contracted (End Systolic Volume - ESV) SV = EDV - ESV
35
What are the three factors that affect stroke volume?
Preload - Degree of stretch of the cardiac muscle cells just before they contract Contractility - Increase in contractile strength that is independent of muscle strength and EDV Afterload - Back Pressure exerted by arterial blood
36
Describe End Systolic Volume?
Determined by the arterial blood pressure and the force of ventricular contraction
37
Describe End Systolic Volume?
Determined by the arterial blood pressure and the force of ventricular contraction
38
What is Preload?
Preload affects EDV - Degree of stretch of the cardiac muscle cells just before they contract Stretching of muscle fibers increases the number of active cross-bridge attachments made between myosin and actin The more muscle fibers stretched, the greater the force of contraction Important factor in stretching cardiac muscle is the EDV - amount of blood returning to the heart and distending the ventricles
39
What is Contractility?
Contractility affects ESV - Increase in contractile strength that is independent of muscle strength and EDV Increases in calcium influx into the cytoplasm from the extracellular fluid and sarcoplasmic reticulum causes more vigorous contractions. A lower ESV and greater SV will result in the complete ejection of blood from the heart thus enhancing contractility. This is a result of increased sympathetic stimulation of the heart. Positive Inotropic Agents (chemicals that influence contractility): Hormones, Ions (Ca2+), drugs Negative Inotropic Agents: acidosis (excess H+ ions, K+)
40
What is Afterload?
Afterload (affects ESV) - Back Pressure exerted by arterial blood The pressure that must be overcome for blood to be ejected from the ventricles (essentially, the back pressure exerted on the aortic and pulmonary valves by arterial blood). High Blood Pressure reduces the ability of the ventricles to eject blood which causes more blood to remain in the heart after systole thus increasing the ESV and reducing SV.
41
What are the two types of cardiac cells?
Cardiomyocytes - cardiac muscle cells | Cardiac Pacemaker Cells - carry impulses that are responsible for the beating of the heart

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