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Questions and Answers
What is the function of the myocardium in the heart?
What is the function of the myocardium in the heart?
- To separate the left and right atria
- To act as a smooth endothelial layer
- To provide the contractile force for pumping blood (correct)
- To receive oxygenated blood from the lungs
Which blood vessel is responsible for carrying deoxygenated blood from the upper body to the right atrium?
Which blood vessel is responsible for carrying deoxygenated blood from the upper body to the right atrium?
- Inferior vena cava
- Pulmonary vein
- Superior vena cava (correct)
- Aorta
What distinguishes the function of the left ventricle from the right ventricle?
What distinguishes the function of the left ventricle from the right ventricle?
- It ejects oxygenated blood to the systemic circulation. (correct)
- It has thinner walls than the right ventricle.
- It ejects blood to the lungs only.
- It receives blood exclusively from the superior vena cava.
Which structure aids in preventing backflow of blood into the atria during ventricular contraction?
Which structure aids in preventing backflow of blood into the atria during ventricular contraction?
In the heart's anatomy, how many chambers receive blood directly from the body?
In the heart's anatomy, how many chambers receive blood directly from the body?
What is the primary function of pulmonary circulation?
What is the primary function of pulmonary circulation?
Which side of the heart pumps oxygen-rich blood to the body?
Which side of the heart pumps oxygen-rich blood to the body?
What is the most direct impact of blood volume on blood pressure?
What is the most direct impact of blood volume on blood pressure?
During which cardiac phase do the ventricles fill with blood?
During which cardiac phase do the ventricles fill with blood?
How does vascular resistance affect blood pressure?
How does vascular resistance affect blood pressure?
What leaves the heart via the aorta?
What leaves the heart via the aorta?
Which vessels are responsible for returning deoxygenated blood to the heart?
Which vessels are responsible for returning deoxygenated blood to the heart?
What happens to blood pressure as the distance from the left ventricle increases?
What happens to blood pressure as the distance from the left ventricle increases?
What does the term 'cardiac output' refer to?
What does the term 'cardiac output' refer to?
Which factor has the least impact on blood pressure?
Which factor has the least impact on blood pressure?
What is the primary source of blood pressure in the cardiovascular system?
What is the primary source of blood pressure in the cardiovascular system?
Which part of the heart receives oxygen-poor blood from the body?
Which part of the heart receives oxygen-poor blood from the body?
What happens during ventricle systole?
What happens during ventricle systole?
What type of blood does the right ventricle receive from the right atrium?
What type of blood does the right ventricle receive from the right atrium?
What structure does the right ventricle pump deoxygenated blood into?
What structure does the right ventricle pump deoxygenated blood into?
Where does the left atrium receive oxygenated blood from?
Where does the left atrium receive oxygenated blood from?
Which structure does the left ventricle pump oxygenated blood into?
Which structure does the left ventricle pump oxygenated blood into?
What is the primary function of the inferior vena cava?
What is the primary function of the inferior vena cava?
How do the right and left ventricles compare in the volume of blood they eject?
How do the right and left ventricles compare in the volume of blood they eject?
What is the characteristic pressure condition under which the right ventricle pumps blood?
What is the characteristic pressure condition under which the right ventricle pumps blood?
Which arteries carry deoxygenated blood from the right ventricle to the lungs?
Which arteries carry deoxygenated blood from the right ventricle to the lungs?
What is the average cardiac output calculated from a stroke volume of 70 mL/beat and a heart rate of 75 beats/min?
What is the average cardiac output calculated from a stroke volume of 70 mL/beat and a heart rate of 75 beats/min?
Which component of blood is responsible for the majority of its volume?
Which component of blood is responsible for the majority of its volume?
Which process described contributes to the cessation of bleeding during haemostasis?
Which process described contributes to the cessation of bleeding during haemostasis?
Which is NOT a function of blood?
Which is NOT a function of blood?
What is the primary function of red blood cells?
What is the primary function of red blood cells?
Which type of white blood cell is primarily known for fighting infections?
Which type of white blood cell is primarily known for fighting infections?
Which part of the blood composition contains the least amount in terms of percentage?
Which part of the blood composition contains the least amount in terms of percentage?
What is the role of haemoglobin in red blood cells?
What is the role of haemoglobin in red blood cells?
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Study Notes
Layers of the Heart Wall
- The heart wall is made of three layers:
- Epicardium (outer)
- Myocardium (middle)
- Endocardium (inner)
Heart Chambers
- The heart has four chambers:
- Two atria (superior)
- Two ventricles (inferior)
Right Atrium
- Receives deoxygenated blood from:
- Superior vena cava (from upper body)
- Inferior vena cava (from lower body)
- Pumps blood to the right ventricle
Right Ventricle
- Receives deoxygenated blood from the right atrium
- Pumps deoxygenated blood into the pulmonary trunk
- Pulmonary trunk branches into the left and right pulmonary arteries
Left Atrium
- Receives oxygenated blood from:
- Pulmonary veins (from lungs)
- Pumps oxygenated blood to the left ventricle
Left Ventricle
- Receives oxygenated blood from the left atrium
- Pumps oxygenated blood to the aorta, which distributes it to the body.
Left vs Right Ventricle
- Both ventricles eject equal blood volumes.
- The right ventricle pumps blood a short distance to the lungs at lower pressure.
- The left ventricle pumps blood a longer distance to the body at a higher pressure.
Systemic vs Pulmonary Circulation
- Pulmonary circulation
- Moves blood between the heart and lungs
- Right side of the heart - leaves via pulmonary arteries
- Systemic circulation
- Moves blood between the heart and the body
- Left side of the heart - leaves via the aorta
Electrical Conduction System of the Heart
- Enables coordinated heart contractions
- Components:
- Sinoatrial (SA) node (pacemaker)
- Atrioventricular (AV) node
- Bundle of His
- Purkinje fibers
- SA node initiates electrical impulses
- AV node delays impulse
- Bundle of His transmits impulse to ventricles
- Purkinje fibers distribute impulse throughout ventricles
Electrocardiogram (ECG)
- A recording of the electrical activity of the heart
- Components:
- P wave: atrial depolarization
- QRS complex: ventricular depolarization
- T wave: ventricular repolarization
Cardiac Cycle
- Complete sequence of events in one heartbeat
- Divided into two phases:
- Diastole: Relaxation phase - ventricles fill with blood
- Systole: Contraction phase - blood is ejected from ventricles
Cardiac Output (CO)
- Volume of blood ejected from the left ventricle per minute.
- Calculated by: CO = Heart Rate (beats/min) x Stroke Volume (mL/beat)
- Factors that influence cardiac output:
- Preload: Amount of stretch of the ventricle before contraction
- Afterload: Resistance the ventricle must overcome to eject blood
- Contractility: Force of contraction of the ventricle
- Autonomic nervous system: Sympathetic (increases HR & contractility) and parasympathetic (decreases HR)
- Hormonal factors: Epinephrine, norepinephrine, thyroid hormones
Functions of Blood
- Transport:
- O2 and CO2
- Nutrients
- Hormones
- Regulation:
- pH
- Temperature
- Protection:
- Clotting
- Antibodies and white blood cells
Components of Blood
- Plasma (55%)
- Suspension medium for formed elements
- Formed elements (45%)
- Red blood cells (erythrocytes) (99%)
- White blood cells (leukocytes)
- Platelets
Red Blood Cells (RBC)
- Transport O2 and CO2
- Biconcave disk shape:
- Increases surface area
- Promotes cell flexibility
- Lack a nucleus and other organelles to maximize oxygen carrying capacity.
- Contain hemoglobin: Oxygen-carrying protein
White Blood Cells (WBC)
- Function in immune defense: Combat invading microbes.
- Contain a nucleus and organelles
- Lack hemoglobin
- Increased levels may indicate an infection
Haemostasis
- Sequence of responses that stop bleeding
- Processes involved:
- Vascular spasm: Smooth muscle in vessel walls contracts to reduce blood flow.
- Platelet plug formation: Platelets adhere to exposed collagen and aggregate to form a plug.
- Coagulation: Blood clotting to form a fibrin mesh to reinforce the platelet plug
Blood Pressure
- The pressure exerted by the blood on the walls of a blood vessel
- Generated by ventricular contraction
- Factors that influence blood pressure:
- Blood volume
- Cardiac output
- Vascular resistance
Vascular Resistance
- Opposition to blood flow due to friction between blood and the walls of blood vessels.
- Factors affecting vascular resistance:
- Size of the lumen
- Blood viscosity
- Total vessel length
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