LGS A-Level OCR Biology - Unit 3 - Structure and Anatomy of the Heart
Blood enters the heart through the vena cava into the right atrium, passes through the tricuspid valve to the right ventricle, and is pumped via the pulmonary artery to the lungs. Oxygenated blood returns through the pulmonary veins to the left atrium, moves through the mitral valve into the left ventricle, and is pumped out through the aorta to the body.
Outline the movement of blood through the heart
vena cava into right atrium
through tricuspid AV valve
right ventricle
semi-lunar valves
pulmonary artery
lungs
pulmonary veins
mitral value
left atrium
left ventricle
aortic valve
aorta
Key Terms
Outline the movement of blood through the heart
vena cava into right atrium
through tricuspid AV valve
right ventricle
semi-lunar valves
pulmonary artery
lungs
What is the heart made out of?
Cardiac muscle
What is the difference between cardiac muscle and skeletal muscle?
Cardiac muscle does not get fatigued and need to rest
Why is the heart described as a double pump?
blood is pumped through the heart twice
first time deoxygenated blood is pumped to lungs
Second time oxygenated blood is pumped to the ...
What is the function of the coronary arteries?
Supply the heart muscle with oxygen and glucose in order to keep it contracting and relaxing all the time
What is the function of pericardial membranes?
Help to prevent the heart from over distending with blood
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| Term | Definition |
|---|---|
Outline the movement of blood through the heart | vena cava into right atrium through tricuspid AV valve right ventricle semi-lunar valves pulmonary artery lungs pulmonary veins mitral value left atrium left ventricle aortic valve aorta |
What is the heart made out of? | Cardiac muscle |
What is the difference between cardiac muscle and skeletal muscle? | Cardiac muscle does not get fatigued and need to rest |
Why is the heart described as a double pump? | blood is pumped through the heart twice first time deoxygenated blood is pumped to lungs Second time oxygenated blood is pumped to the body |
What is the function of the coronary arteries? | Supply the heart muscle with oxygen and glucose in order to keep it contracting and relaxing all the time |
What is the function of pericardial membranes? | Help to prevent the heart from over distending with blood |
Is the wall of the left ventricle thicker than the right? | Yes |
Why is the wall of the right ventricle thinner than the wall of the left ventricle? | the right side only has to pump blood to the lungs which are close to the heart right side must only overcome resistance of the pulmonary circulation |
Why is the wall of the left ventricle thicker than the wall of the right ventricle? | the left side must provide sufficient force to overcome the resistance of the aorta and arterial systems of the whole body left side must move the blood under pressure to all extremities of the body |
As the atrium fills with blood what happens to atrial pressure? | It increases |
How is cardiac muscle described? | Myogenic |
What does myogenic mean? | Heart muscle has its own intrinsic rhythm |
As ventricular pressure increases, what happens to aortic pressure? Why? | It increases Blood flows into the aorta at high pressure |
What is the sino-atrial node? and what is its function? | Region of the heart that initiates a wave of excitation that triggers the contraction of the heart |
What is the sino-atrial node also known as? | The pacemaker region |
What is the atrio-ventricular node? and what is its function? | Stimulates the ventricles to contract after a slight delay |
Why does the atrio-ventricular node impose a slight delay? | To ensure atrial contraction is complete |
What is the bundle of His? | Conducting tissue made of purkyne fibres that passes through the septum |
What are Purkyne fibres? | Tissue that conducts the wave of excitation to the apex of the heart |
What is the function of the septum? | Prevents the mixing of oxygenated and deoxygenated blood |
What is the function of the valves in the heart? | Prevent backflow of blood and so ensure efficient movement of blood |
What is the function of the tendinous cords? | Connect papillary muscles to the valves and help to prevent prolapse of the valves |
Why does hydrostatic pressure of blood drop as blood moves away from the heart? | divides into smaller vessels vessels have larger total cross sectional area loss of plasma from the capillaries |