Cardiac cycle Flashcards
What is the primary function of the heart?
To pump blood throughout the body.
What are the four main chambers of the heart?
Right atrium, right ventricle, left atrium, left ventricle.
True or False: The right atrium receives oxygenated blood.
False.
Fill in the blank: Blood enters the right atrium from the ______ and ______.
superior vena cava; inferior vena cava.
What valve separates the right atrium from the right ventricle?
Tricuspid valve.
What happens to blood in the right ventricle?
It is pumped to the lungs for oxygenation.
True or False: The pulmonary valve is located between the right ventricle and the aorta.
False.
What is the function of the pulmonary arteries?
To carry deoxygenated blood from the heart to the lungs.
Fill in the blank: After oxygenation, blood returns to the heart via the ______ veins.
pulmonary.
What valve is located between the left atrium and left ventricle?
Mitral valve.
What is the main role of the left ventricle?
To pump oxygenated blood to the rest of the body.
True or False: The aortic valve prevents backflow into the left atrium.
False.
What large artery carries blood from the left ventricle?
Aorta.
What is the term for the cycle of blood flow through the heart?
Cardiac cycle.
Multiple choice: Which chamber of the heart has the thickest walls?
Left ventricle.
What structure prevents backflow of blood in the heart?
Valves.
Fill in the blank: The ______ system controls the heart’s rhythm.
electrical conduction.
What is the role of the sinoatrial (SA) node?
To act as the natural pacemaker of the heart.
True or False: Blood flows from the aorta directly to the right atrium.
False.
What is the term for the phase when the heart muscle relaxes?
Diastole.
What is the term for the phase when the heart muscle contracts?
Systole.
Fill in the blank: The ______ is responsible for supplying the heart muscle with blood.
coronary arteries.
What is the average heart rate for adults at rest?
60 to 100 beats per minute.
What does the term ‘cardiac output’ refer to?
The volume of blood the heart pumps per minute.
Multiple choice: Which of the following is a major risk factor for heart disease?
High blood pressure.
What is the significance of the foramen ovale in fetal circulation?
It allows blood to bypass the lungs.
Fill in the blank: The ______ connects the right and left atria in fetal circulation.
foramen ovale.
What are the two main components of blood?
Plasma and formed elements
Plasma constitutes about 55-60% of total blood volume, while formed elements make up 40-45%.
What percentage of plasma is water?
90%
Water is the primary component of plasma.
What are the three types of formed elements in blood?
- Red blood cells (erythrocytes)
- White blood cells (leucocytes)
- Platelets (thrombocytes)
Red blood cells transport oxygen, white blood cells protect against disease, and platelets are responsible for clotting.
What is the primary function of red blood cells?
Transport oxygen
Red blood cells bind oxygen to haemoglobin.
What percentage of formed elements volume do red blood cells account for?
More than 99%
White blood cells and platelets together account for less than 1%.
What is haematocrit?
The percentage of total blood volume that is erythrocytes
The average haematocrit is 45% in men and 42% in women.
What protein in plasma is key for blood clot formation?
Fibrinogen
Fibrinogen entangles blood cells and debris to form a clot.
Fill in the blank: The average haematocrit is ______% in men.
45
The average haematocrit for women is 42%.
What two processes control bleeding when a blood vessel is injured?
- Platelet aggregation to form a plug
- Blood clotting
These processes work together to minimize blood loss.
True or False: Elevated fibrinogen levels decrease the risk of heart attack.
False
Elevated fibrinogen levels increase the propensity for blood to clot, raising the risk of heart attack, stroke, and peripheral arterial disease.
What is the function of haemoglobin in red blood cells?
Binds oxygen
Haemoglobin is composed of globin (a protein) and haem (a pigment containing iron).
What type of system is the systemic circulation?
A high-pressure system.
How much more resistance to flow does the systemic circulation offer compared to the pulmonary circulation?
About six times more resistance.
What anatomical feature reflects the greater thickness of the left ventricle wall compared to the right?
The high pressure of the systemic circulation.
What is the purpose of the high pressure in systemic circulation?
To ensure that blood is circulated with sufficient force and velocity to perfuse all vital organs and tissues.
Is the pressure and velocity of blood flow constant throughout the systemic circulation?
No, it is not constant.
What is the typical systolic pressure within the aorta in a healthy individual at rest?
About 120 mmHg.
What is the typical diastolic pressure within the aorta in a healthy individual at rest?
About 70 mmHg.
What happens to the pressure as the aorta branches into smaller arteries and capillaries?
The pressure decreases.
What analogy is used to explain the decrease in blood flow velocity through smaller vessels?
A hosepipe supplying water to thousands of smaller hoses.
What is one reason there is insufficient pressure in the peripheral venous system to return blood to the heart?
Particularly from the lower parts of the body.
What is one mechanism that facilitates venous return to the heart?
Skeletal muscle action (skeletal muscle pump).
What role do valves play in the venous system?
They prevent backflow and consequent pooling in the lower extremities.
Fill in the blank: The pressure within the aorta during systole is about _______.
120 mmHg.
Fill in the blank: The pressure within the aorta during diastole is about _______.
70 mmHg.
True or False: The systemic circulation has lower resistance compared to the pulmonary circulation.
False.
What anatomical structure is primarily responsible for the high pressure in the systemic circulation?
Left ventricle.
What is the cardiac cycle?
The sequence of events in the heart during one complete heartbeat.
It includes all phases of heart activity, including contraction and relaxation.
What happens during the phase when blood is ejected into systemic & pulmonary circulations?
Blood is pumped from the ventricles into the aorta and pulmonary artery.
This occurs during ventricular contraction.
What occurs after the aortic & pulmonary valves close?
Both ventricles & atria relax.
This phase is known as diastole.
What starts atrial filling?
Pressure increases in the atria.
This pressure difference allows blood to flow from the veins into the atria.
What happens when the A-V valves open?
80% of end-diastolic volume (EDV) flows into the ventricles.
This occurs during the early phase of diastole.
What percentage of end-diastolic volume (EDV) flows into the ventricles when the atria contract?
20% of EDV.
This occurs just before ventricular contraction.
What begins with ventricular contraction?
Ventricular pressure increases.
This leads to the closure of the A-V valves.
What happens to the A-V valves during ventricular contraction?
The A-V valves shut.
This prevents backflow into the atria.
What occurs during the phase of no filling / no ejection?
Ventricular pressure is greater than aortic & pulmonary artery pressure.
This phase is part of isovolumetric contraction.
