Unit 3 - Structure and anatomy of the heart

Question 1

Outline the movement of blood through the heart

Answer 1

• vena cava into right atrium
• through tricuspid AV valve
• right ventricle
• semi-lunar valves
• pulmonary artery
• lungs
• pulmonary veins
• mitral value
• left atrium
• through bicuspid valve
• left ventricle
• semi-lunar valve
• aorta

Question 2

What is the heart made out of?

Answer 2

Cardiac muscle

Question 3

What is the difference between cardiac muscle and skeletal muscle?

Answer 3

Cardiac muscle does not get fatigued and need to rest

Question 4

Why is the heart described as a double pump?

Answer 4

• blood is pumped through the heart twice
• first time deoxygenated blood is pumped to lungs
• Second time oxygenated blood is pumped to the body

Question 5

What is the function of the coronary arteries?

Answer 5

Supply the heart muscle with oxygen and glucose in order to keep it contracting and relaxing all the time

Question 6

What is the function of pericardial membranes?

Answer 6

Help to prevent the heart from over distending with blood

Question 7

Is the wall of the left ventricle thicker than the right?

Answer 7

Yes

Question 8

Why is the wall of the right ventricle thinner than the wall of the left ventricle?

Answer 8

• 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

Question 9

Why is the wall of the left ventricle thicker than the wall of the right ventricle?

Answer 9

• 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

Question 10

As the atrium fills with blood what happens to atrial pressure?

Answer 10

It increases

Question 11

How is cardiac muscle described?

Answer 11

Myogenic

Question 12

What does myogenic mean?

Answer 12

Heart muscle has its own intrinsic rhythm

Question 13

As ventricular pressure increases, what happens to aortic pressure?

Why?

Answer 13

It increases

Blood flows into the aorta at high pressure

Question 14

What is the sino-atrial node? and what is its function?

Answer 14

Region of the heart that initiates a wave of excitation that triggers the contraction of the heart

Question 15

What is the sino-atrial node also known as?

Answer 15

The pacemaker region

Question 16

What is the atrio-ventricular node? and what is its function?

Answer 16

Stimulates the ventricles to contract after a slight delay

Question 17

Why does the atrio-ventricular node impose a slight delay?

Answer 17

To ensure atrial contraction is complete, before ventricular contraction is initiated

Question 18

What is the bundle of His?

Answer 18

Conducting tissue made of purkyne fibres that passes through the septum

Question 19

What are Purkyne fibres?

Answer 19

Tissue that conducts the wave of excitation to the apex of the heart

Question 20

What is the function of the septum?

Answer 20

Prevents the mixing of oxygenated and deoxygenated blood

Question 21

What is the function of the valves in the heart?

Answer 21

Prevent backflow of blood and so ensure efficient movement of blood

Question 22

What is the function of the tendinous cords?

Answer 22

Connect papillary muscles to the valves and help to prevent prolapse of the valves

Question 23

Why does hydrostatic pressure of blood drop as blood moves away from the heart?

Answer 23

• divides into smaller vessels
• vessels have larger total cross sectional area
• loss of plasma from the capillaries