Ch.26 - The Heart and Blood Vessels

Question 1

What is an open circulatory system?

Answer 1

An open circulatory system means blood leaves blood vessels and flows around the cells of the animal’s body before re-entering blood vessels again.

Question 2

What is a closed circulatory system?

Answer 2

A closed circulatory system means blood remains in a continuous system of blood vessels.

Question 3

What is the need(or lack thereof) for a circulatory system in organisms?

Answer 3

Amoeba don’t need a circulatory system, diffusion is adequate because the organism is only a few cells thick. Larger organisms need a circulatory system to supply their cells with all the materials they require.

Question 4

Why is a closed system more efficient than an open system?

Answer 4

Blood can be pumped around the body faster. Animals with a closed circulatory system have a higher metabolic rate. A closed system allows the flow of blood to different organs to be increased or decreased bases on demand.

Question 5

What are the types of blood vessels?

Answer 5

The three main types of blood vessels are arteries which carry blood away from the heart. Arteries divide smaller into arterioles. Veins carry blood to the heart. Small veins are called venules. Capillaries are tiny vessels that link arteries and veins.

Question 6

What are the three layers of arteries and veins?

Answer 6

The outer layer of inelastic protein(collagen) prevents the walls from over-expansion. The middle layer of involuntary muscle and elastic fibres. This layer alters the size of the vessel. The inner layer is called the endothelium and it surround the lumen.

Question 7

Draw a transverse section of an artery and a vein.

Answer 7

Question 8

What is blood pressure?

Answer 8

Blood pressure is the force that blood exerts against the wall of a blood vessel. Typical blood pressure is 120/80 mm Hg

Question 9

What are valves?

Answer 9

Valves control the direction of blood flow. They prevent back flow of the blood.

Question 10

How does blood pressure come about?

Answer 10

When the heart contracts, blood pressure is high in arteries. The pressure causes the artery to expand and this can be detected as a pulse.

Question 11

Where is the heart located, what is it made of?

Answer 11

The heart is located between the 2 lungs, slightly to the left of the thorax and just above the diaphragm. It is made of cardiac muscle(contractile tissue) and surrounded by (a double membrane called) the pericardium. Pericardial fluid between these 2 membranes reduces friction when the heart beats.

Question 12

Draw a diagram of the structure of the heart.

Answer 12

Question 13

What are ventricles?

Answer 13

Ventricles pump blood out of the heart. As the left ventricle pumps blood to the head and body, it is a much longer circuit and the left ventricular wall is much thicker and stronger than the right.

Question 14

Draw a diagram of the heart’s blood flow.

Answer 14

Question 15

What are the advantages of a double circulation system in comparison to single circulation.

Answer 15

A double circulation system allows oxygen-rich and oxygen-poor blood to be kept separate. It also ensures that blood pressure is high enough to reach all parts of the body.

Question 16

What is a portal system?

Answer 16

A portal system is a blood pathway that begins and ends in capillaries.

Question 17

How is blood supplied to the heart’s muscle?

Answer 17

The heart’s muscle is supplied with blood by the coronary arteries which branch from the aorta at the point where it leaves the heart. Blood is drained from the muscles of the heart by coronary veins.

Question 18

What is angina?

Answer 18

Angina are chest pains that precede a heart attack due to blockage of the coronary arteries.

Question 19

What controls the heartbeat?

Answer 19

The sinoatrial node(pacemaker) sends electrical impulses which contracts the atria. The atrioventricular node sends electrical impulses which contract the ventricles.

Question 20

What is diastole?

Answer 20

Diastole is when the chambers of the heart relax.

Question 21

What is systole?

Answer 21

Systole is when the chambers of the heart contract.

Question 22

What are the stages of the cardiac cycle(heartbeat).

Answer 22

There are 3 stages during one heartbeat.
Blood enters the heart: atrioventricular diastole, blood enters the atria and all valves are closed.
Blood is pumped from the atria to the ventricles: atrial systole due to impulses from the pacemaker, blood is pumped to the ventricles, tricuspid and bicuspid valves open, veins close and semilunar valves remain closed.
Blood leaves the heart: Atria relax, ventricular systole due to impulses from AV node, blood is forced out of the semilunar valves and arteries, the pressure closes the bicuspid and tricuspid valves.
Finally, semilunar valves close, the vena cava and pulmonary veins open and the cycle starts again.

Question 23

What is a heart murmur?

Answer 23

A heart murmur is any abnormal sound associated with the heartbeat. A heart murmur may indicate damage to the valves.

Question 24

What is a pulse?

Answer 24

A pulse is the alternate expansion and contraction of the arteries. The contraction is caused by the elastic walls of the arteries. Average pulse 72bpm.

Question 25

How does smoking affect the circulatory system?

Answer 25

The nicotine in tobacco increases heart rate and raises blood pressure.

Question 26

Hoe does diet affect the circulatory system?

Answer 26

Harmful fats such as red meat and dairy foods are high in cholesterol. Cholesterol increases risk of blocked arteries, called plaques. High salt intake causes high blood pressure. Obesity may cause high blood pressure and heart attacks.

Question 27

How does exercise affect the circulatory system?

Answer 27

Exercise enlargens and strengthens the heart. Exercise improves circulation, increases heart rate and reduces weight.

Question 28

What is contractile tissue?

Answer 28

Contractile tissue is muscle that has the capacity to contract and relax.

Question 29

How is blood moved through the veins?

Answer 29

Blood moves through the veins by the contracting of muscles and valves that prevent backflow.