Physiology of cardiac system | Cardiopulmonary system

Anatomy

The heart is a muscle that pumps blood throughout the body’s systems. The left side of the heart pumps oxygenated blood from the lungs to all body systems via the arterial supply. Blood then returns to the right side of the heart via the venous system, where waste products are excreted by various organs. The right side then pumps deoxygenated blood into the lungs, where carbon dioxide (CO2) is released, and oxygen is absorbed. This cycle repeats with each heartbeat.

The heart consists of:

External walls
Blood-filled chambers
Valves that allow blood to flow through the chambers
Blood vessels that carry blood to the other structures
Electrical signaling conduction system

The three walls of the heart are:

Endocardium; innermost layer
Myocardium: muscular middle layer
Epicardium: outermost layer

Chambers of the heart:

Right atrium
Right ventricle
Left atrium
Left ventricle

Valves of the heart:

Atrioventricular valves:
- Tricuspid valve: lies between the right atrium and the right ventricle
- Mitral valve: lies between the left atrium and left ventricle
Semilunar valves:
- Aortic valve: oxygenated blood flows from the left ventricle to the aorta
- Pulmonary valve: deoxygenated blood flows from the right ventricle to the pulmonary artery

Blood vessels:

Arteries: carry oxygenated blood
Veins: carry deoxygenated blood
Capillaries: small blood vessels for the exchange of deoxygenated and oxygenated blood

Chambers of the heart

The heart is separated into four chambers that work to ensure blood flow occurs in the right direction. The left and right sides of the heart work separately to ensure blood reaches either the lungs or the body system. The right side of the heart pumps deoxygenated blood to the lungs, where gas exchange occurs. The left side pumps oxygenated blood to the rest of the body.

Definitions

Aorta: Transports oxygenated blood from the heart to the peripheral systems
Right atrium: Receives deoxygenated blood from the body system and then pumps it to the right ventricle
Right ventricle: Receives blood from the right atrium and pumps deoxygenated blood through the pulmonary valve into the pulmonary artery to the lungs for oxygenation
Left atrium: Receives oxygenated blood from the lungs via four pulmonary veins
Left ventricle: Receives oxygenated blood from the left atrium and pumps oxygenated blood into the aorta, distributing it to the brain, organs, and tissues.
Superior vena cava: Large vein that carries deoxygenated blood from the head, chest, arm, and neck
Inferior vena cava:: Large vein that carries deoxygenated blood from the feet, legs, and abdomen

Blood flow through the heart: step-by-step

Deoxygenated blood returns to the heart:
- Blood low in oxygen returns from the body to the heart through two major veins:
  - Superior vena cava (SVC): returns blood from the upper body
  - Inferior vena cava (IVC): returns blood from the lower body
- Both veins empty into the right atrium.
Right atrium
- Deoxygenated blood enters the right atrium, the upper right chamber of the heart.
- Blood then flows through the tricuspid valve into the right ventricle.ventricle.
Right ventricle
- The right ventricle pumps deoxygenated blood through the pulmonary semilunar valve into the pulmonary arteries.
Pulmonary arteries to the lungs
- The pulmonary arteries carry deoxygenated blood from the heart to the lungs.
  - This is an important exception because most arteries carry oxygenated blood.
Lungs oxygenate the blood
- In the lungs, carbon dioxide (CO₂) is removed and oxygen (O₂) is added to the blood through gas exchange at the alveoli.
- The blood is now oxygenated.
Left atrium
- Oxygen-rich blood returns to the heart through the pulmonary veins and enters the left atrium, the upper left chamber of the heart.
  - This is another important exception because pulmonary veins carry oxygenated blood.
- Blood then passes through the mitral (bicuspid) valve into the left ventricle.
Left ventricle
- The left ventricle pumps oxygenated blood through the aortic semilunar valve into the aorta.
- The left ventricle has the thickest myocardium because it must generate enough force to pump blood throughout the entire body.
Aorta to the body
- The aorta distributes oxygen-rich blood to the systemic circulation, supplying tissues and organs throughout the body.

Electrical signals in the heart

Electrical signals within the heart act as a pacemaker to the heart by assisting with controlling heart rate, coordinating the heart chambers (atria and ventricles), adapting to the changing needs of the body, and ensuring appropriate circulation.

Definitions

Sinoatrial node: The sinoatrial (SA) node initiates the normal heart rhythm sending blood from the atria into the ventricles
Atrioventricular Bundle: A bundle of electrically charged cardiomyocytes that causes blood to move from the atrium to the ventricle
Bundle of His: A specialized group of conductive cardiac fibers that carries electrical impulses from the AV node to the right and left bundle branches, helping coordinate ventricular depolarization and contraction.
Purkinje fibers: Specialized conductive fibers located within the ventricular walls that rapidly transmit electrical impulses throughout the ventricles, producing coordinated contraction of the right and left ventricles.

Crucial factors of cardiac function

The amount of blood pumped with each heartbeat is crucial to maintaining the vitality of the lungs and the peripheral system. The principles that are important in this process are preload and afterload. If there is dysfunction in either of these components, then the individual may experience stroke, myocardial infarction, or death.

Definitions

Preload: The amount of ventricular stretch at the end of diastole, primarily determined by the volume of blood filling the ventricles (end-diastolic volume)
Afterload: The resistance or pressure the ventricles must overcome to eject blood during systole.
Stroke volume: Amount of blood pumped out by the ventricle at the end of each contraction
Cardiac output: Heart rate multiplied by stroke volume to determine how much blood is pumped from the ventricles in liters per minute
Diastole: Relaxation of atrium and ventricles
Systole: Contraction of the atrium and ventricle

Anatomy of the Heart

Heart pumps blood through body systems; left side: oxygenated blood to body, right side: deoxygenated blood to lungs
Main structures: external walls, chambers, valves, blood vessels, electrical conduction system
Three heart wall layers: endocardium (inner), myocardium (muscular middle), epicardium (outer)

Heart Chambers

Four chambers: right atrium, right ventricle, left atrium, left ventricle
Right side: receives deoxygenated blood, sends to lungs
Left side: receives oxygenated blood, sends to body

Heart Valves

Atrioventricular valves:
- Tricuspid (right atrium to right ventricle)
- Mitral (left atrium to left ventricle)
Semilunar valves:
- Pulmonary (right ventricle to pulmonary artery)
- Aortic (left ventricle to aorta)

Blood Vessels

Arteries: carry oxygenated blood (except pulmonary arteries)
Veins: carry deoxygenated blood (except pulmonary veins)
Capillaries: site of gas and nutrient exchange

Blood Flow Through the Heart

Deoxygenated blood returns via superior/inferior vena cava → right atrium → right ventricle → pulmonary arteries → lungs
Oxygenated blood returns via pulmonary veins → left atrium → left ventricle → aorta → body

Key Blood Flow Structures

Aorta: main artery for oxygenated blood to body
Superior vena cava: drains upper body
Inferior vena cava: drains lower body
Pulmonary arteries: carry deoxygenated blood to lungs
Pulmonary veins: return oxygenated blood to heart

Electrical Signals in the Heart

SA node: initiates heartbeat, sets rhythm
AV bundle (Bundle of His): transmits signals from atria to ventricles
Purkinje fibers: spread electrical impulse for coordinated ventricular contraction

Crucial Factors of Cardiac Function

Preload: blood volume in ventricles at end of diastole
Afterload: resistance heart must overcome to eject blood
Stroke volume: blood pumped per ventricular contraction
Cardiac output: heart rate × stroke volume (L/min)
Diastole: heart relaxation phase
Systole: heart contraction phase

Anatomy

The heart consists of:

External walls
Blood-filled chambers
Valves that allow blood to flow through the chambers
Blood vessels that carry blood to the other structures
Electrical signaling conduction system

The three walls of the heart are:

Endocardium; innermost layer
Myocardium: muscular middle layer
Epicardium: outermost layer

Chambers of the heart:

Right atrium
Right ventricle
Left atrium
Left ventricle

Valves of the heart:

Atrioventricular valves:
- Tricuspid valve: lies between the right atrium and the right ventricle
- Mitral valve: lies between the left atrium and left ventricle
Semilunar valves:
- Aortic valve: oxygenated blood flows from the left ventricle to the aorta
- Pulmonary valve: deoxygenated blood flows from the right ventricle to the pulmonary artery

Blood vessels:

Arteries: carry oxygenated blood
Veins: carry deoxygenated blood
Capillaries: small blood vessels for the exchange of deoxygenated and oxygenated blood

Chambers of the heart

Definitions

Aorta: Transports oxygenated blood from the heart to the peripheral systems
Right atrium: Receives deoxygenated blood from the body system and then pumps it to the right ventricle
Right ventricle: Receives blood from the right atrium and pumps deoxygenated blood through the pulmonary valve into the pulmonary artery to the lungs for oxygenation
Left atrium: Receives oxygenated blood from the lungs via four pulmonary veins
Left ventricle: Receives oxygenated blood from the left atrium and pumps oxygenated blood into the aorta, distributing it to the brain, organs, and tissues.
Superior vena cava: Large vein that carries deoxygenated blood from the head, chest, arm, and neck
Inferior vena cava:: Large vein that carries deoxygenated blood from the feet, legs, and abdomen

Blood flow through the heart: step-by-step

Deoxygenated blood returns to the heart:
- Blood low in oxygen returns from the body to the heart through two major veins:
  - Superior vena cava (SVC): returns blood from the upper body
  - Inferior vena cava (IVC): returns blood from the lower body
- Both veins empty into the right atrium.
Right atrium
- Deoxygenated blood enters the right atrium, the upper right chamber of the heart.
- Blood then flows through the tricuspid valve into the right ventricle.ventricle.
Right ventricle
- The right ventricle pumps deoxygenated blood through the pulmonary semilunar valve into the pulmonary arteries.
Pulmonary arteries to the lungs
- The pulmonary arteries carry deoxygenated blood from the heart to the lungs.
  - This is an important exception because most arteries carry oxygenated blood.
Lungs oxygenate the blood
- In the lungs, carbon dioxide (CO₂) is removed and oxygen (O₂) is added to the blood through gas exchange at the alveoli.
- The blood is now oxygenated.
Left atrium
- Oxygen-rich blood returns to the heart through the pulmonary veins and enters the left atrium, the upper left chamber of the heart.
  - This is another important exception because pulmonary veins carry oxygenated blood.
- Blood then passes through the mitral (bicuspid) valve into the left ventricle.
Left ventricle
- The left ventricle pumps oxygenated blood through the aortic semilunar valve into the aorta.
- The left ventricle has the thickest myocardium because it must generate enough force to pump blood throughout the entire body.
Aorta to the body
- The aorta distributes oxygen-rich blood to the systemic circulation, supplying tissues and organs throughout the body.

Electrical signals in the heart

Definitions

Sinoatrial node: The sinoatrial (SA) node initiates the normal heart rhythm sending blood from the atria into the ventricles
Atrioventricular Bundle: A bundle of electrically charged cardiomyocytes that causes blood to move from the atrium to the ventricle
Bundle of His: A specialized group of conductive cardiac fibers that carries electrical impulses from the AV node to the right and left bundle branches, helping coordinate ventricular depolarization and contraction.
Purkinje fibers: Specialized conductive fibers located within the ventricular walls that rapidly transmit electrical impulses throughout the ventricles, producing coordinated contraction of the right and left ventricles.

Crucial factors of cardiac function

Definitions

Preload: The amount of ventricular stretch at the end of diastole, primarily determined by the volume of blood filling the ventricles (end-diastolic volume)
Afterload: The resistance or pressure the ventricles must overcome to eject blood during systole.
Stroke volume: Amount of blood pumped out by the ventricle at the end of each contraction
Cardiac output: Heart rate multiplied by stroke volume to determine how much blood is pumped from the ventricles in liters per minute
Diastole: Relaxation of atrium and ventricles
Systole: Contraction of the atrium and ventricle

Anatomy of the Heart

Heart pumps blood through body systems; left side: oxygenated blood to body, right side: deoxygenated blood to lungs
Main structures: external walls, chambers, valves, blood vessels, electrical conduction system
Three heart wall layers: endocardium (inner), myocardium (muscular middle), epicardium (outer)

Heart Chambers

Four chambers: right atrium, right ventricle, left atrium, left ventricle
Right side: receives deoxygenated blood, sends to lungs
Left side: receives oxygenated blood, sends to body

Heart Valves

Atrioventricular valves:
- Tricuspid (right atrium to right ventricle)
- Mitral (left atrium to left ventricle)
Semilunar valves:
- Pulmonary (right ventricle to pulmonary artery)
- Aortic (left ventricle to aorta)

Blood Vessels

Arteries: carry oxygenated blood (except pulmonary arteries)
Veins: carry deoxygenated blood (except pulmonary veins)
Capillaries: site of gas and nutrient exchange

Blood Flow Through the Heart

Deoxygenated blood returns via superior/inferior vena cava → right atrium → right ventricle → pulmonary arteries → lungs
Oxygenated blood returns via pulmonary veins → left atrium → left ventricle → aorta → body

Key Blood Flow Structures

Aorta: main artery for oxygenated blood to body
Superior vena cava: drains upper body
Inferior vena cava: drains lower body
Pulmonary arteries: carry deoxygenated blood to lungs
Pulmonary veins: return oxygenated blood to heart

Electrical Signals in the Heart

SA node: initiates heartbeat, sets rhythm
AV bundle (Bundle of His): transmits signals from atria to ventricles
Purkinje fibers: spread electrical impulse for coordinated ventricular contraction

Crucial Factors of Cardiac Function

Preload: blood volume in ventricles at end of diastole
Afterload: resistance heart must overcome to eject blood
Stroke volume: blood pumped per ventricular contraction
Cardiac output: heart rate × stroke volume (L/min)
Diastole: heart relaxation phase
Systole: heart contraction phase

Anatomy

The heart consists of:

External walls
Blood-filled chambers
Valves that allow blood to flow through the chambers
Blood vessels that carry blood to the other structures
Electrical signaling conduction system

The three walls of the heart are:

Endocardium; innermost layer
Myocardium: muscular middle layer
Epicardium: outermost layer

Chambers of the heart:

Right atrium
Right ventricle
Left atrium
Left ventricle

Valves of the heart:

Atrioventricular valves:
- Tricuspid valve: lies between the right atrium and the right ventricle
- Mitral valve: lies between the left atrium and left ventricle
Semilunar valves:
- Aortic valve: oxygenated blood flows from the left ventricle to the aorta
- Pulmonary valve: deoxygenated blood flows from the right ventricle to the pulmonary artery

Blood vessels:

Arteries: carry oxygenated blood
Veins: carry deoxygenated blood
Capillaries: small blood vessels for the exchange of deoxygenated and oxygenated blood

Chambers of the heart

Definitions

Aorta: Transports oxygenated blood from the heart to the peripheral systems
Right atrium: Receives deoxygenated blood from the body system and then pumps it to the right ventricle
Right ventricle: Receives blood from the right atrium and pumps deoxygenated blood through the pulmonary valve into the pulmonary artery to the lungs for oxygenation
Left atrium: Receives oxygenated blood from the lungs via four pulmonary veins
Left ventricle: Receives oxygenated blood from the left atrium and pumps oxygenated blood into the aorta, distributing it to the brain, organs, and tissues.
Superior vena cava: Large vein that carries deoxygenated blood from the head, chest, arm, and neck
Inferior vena cava:: Large vein that carries deoxygenated blood from the feet, legs, and abdomen

Blood flow through the heart: step-by-step

Deoxygenated blood returns to the heart:
- Blood low in oxygen returns from the body to the heart through two major veins:
  - Superior vena cava (SVC): returns blood from the upper body
  - Inferior vena cava (IVC): returns blood from the lower body
- Both veins empty into the right atrium.
Right atrium
- Deoxygenated blood enters the right atrium, the upper right chamber of the heart.
- Blood then flows through the tricuspid valve into the right ventricle.ventricle.
Right ventricle
- The right ventricle pumps deoxygenated blood through the pulmonary semilunar valve into the pulmonary arteries.
Pulmonary arteries to the lungs
- The pulmonary arteries carry deoxygenated blood from the heart to the lungs.
  - This is an important exception because most arteries carry oxygenated blood.
Lungs oxygenate the blood
- In the lungs, carbon dioxide (CO₂) is removed and oxygen (O₂) is added to the blood through gas exchange at the alveoli.
- The blood is now oxygenated.
Left atrium
- Oxygen-rich blood returns to the heart through the pulmonary veins and enters the left atrium, the upper left chamber of the heart.
  - This is another important exception because pulmonary veins carry oxygenated blood.
- Blood then passes through the mitral (bicuspid) valve into the left ventricle.
Left ventricle
- The left ventricle pumps oxygenated blood through the aortic semilunar valve into the aorta.
- The left ventricle has the thickest myocardium because it must generate enough force to pump blood throughout the entire body.
Aorta to the body
- The aorta distributes oxygen-rich blood to the systemic circulation, supplying tissues and organs throughout the body.

Electrical signals in the heart

Definitions

Sinoatrial node: The sinoatrial (SA) node initiates the normal heart rhythm sending blood from the atria into the ventricles
Atrioventricular Bundle: A bundle of electrically charged cardiomyocytes that causes blood to move from the atrium to the ventricle
Bundle of His: A specialized group of conductive cardiac fibers that carries electrical impulses from the AV node to the right and left bundle branches, helping coordinate ventricular depolarization and contraction.
Purkinje fibers: Specialized conductive fibers located within the ventricular walls that rapidly transmit electrical impulses throughout the ventricles, producing coordinated contraction of the right and left ventricles.

Crucial factors of cardiac function

Definitions

Preload: The amount of ventricular stretch at the end of diastole, primarily determined by the volume of blood filling the ventricles (end-diastolic volume)
Afterload: The resistance or pressure the ventricles must overcome to eject blood during systole.
Stroke volume: Amount of blood pumped out by the ventricle at the end of each contraction
Cardiac output: Heart rate multiplied by stroke volume to determine how much blood is pumped from the ventricles in liters per minute
Diastole: Relaxation of atrium and ventricles
Systole: Contraction of the atrium and ventricle

Anatomy of the Heart

Heart pumps blood through body systems; left side: oxygenated blood to body, right side: deoxygenated blood to lungs
Main structures: external walls, chambers, valves, blood vessels, electrical conduction system
Three heart wall layers: endocardium (inner), myocardium (muscular middle), epicardium (outer)

Heart Chambers

Four chambers: right atrium, right ventricle, left atrium, left ventricle
Right side: receives deoxygenated blood, sends to lungs
Left side: receives oxygenated blood, sends to body

Heart Valves

Atrioventricular valves:
- Tricuspid (right atrium to right ventricle)
- Mitral (left atrium to left ventricle)
Semilunar valves:
- Pulmonary (right ventricle to pulmonary artery)
- Aortic (left ventricle to aorta)

Blood Vessels

Arteries: carry oxygenated blood (except pulmonary arteries)
Veins: carry deoxygenated blood (except pulmonary veins)
Capillaries: site of gas and nutrient exchange

Blood Flow Through the Heart

Deoxygenated blood returns via superior/inferior vena cava → right atrium → right ventricle → pulmonary arteries → lungs
Oxygenated blood returns via pulmonary veins → left atrium → left ventricle → aorta → body

Key Blood Flow Structures

Aorta: main artery for oxygenated blood to body
Superior vena cava: drains upper body
Inferior vena cava: drains lower body
Pulmonary arteries: carry deoxygenated blood to lungs
Pulmonary veins: return oxygenated blood to heart

Electrical Signals in the Heart

SA node: initiates heartbeat, sets rhythm
AV bundle (Bundle of His): transmits signals from atria to ventricles
Purkinje fibers: spread electrical impulse for coordinated ventricular contraction

Crucial Factors of Cardiac Function

Preload: blood volume in ventricles at end of diastole
Afterload: resistance heart must overcome to eject blood
Stroke volume: blood pumped per ventricular contraction
Cardiac output: heart rate × stroke volume (L/min)
Diastole: heart relaxation phase
Systole: heart contraction phase