Circulatory System

Question 1

Explain the composition of blood

Answer 1

Plasma - 55%
White blood cells and platelets - less than 1%
Red blood cells - 45 %

Question 2

Explain red blood cells

Answer 2

Can also be referred to as erythrocytes or lymphocytes. They are usually shaped like bicomcave disks and are made from bone marrow. They have a protein called hemoglobin in them.

Question 3

What is hemoglobin? Why is it important red blood cells have it?

Answer 3

Hemoglobin is a protein that contains iron. This makes it a good way to transport O2 and CO2.

Question 4

Explain blood cells and platelets.

Answer 4

WBC are also called leukocytes and help to fight infection. A high number of WBC are a symptom of leukaemia.
Platelets are leftover fragments of bone marrow and are involved in blood clotting.

Question 5

Explain plasma

Answer 5

It is mostly water. Plasma that escapes the vessels is absorbed by the tissues.

Question 6

Explain the three different blood vessels

Answer 6

Arteries: high blood pressure, elastic fibres
Veins: low blood pressure, have thin wall but large inner circumference
Capillaries: smallest, wall is a single layer of epithelial cells

Question 7

Go into more detail about veins

Answer 7

Veins have valves to keep blood moving to the heart and to prevent backflow

Question 8

Explain the flow of blood through the body.

Answer 8

1. Body tissue
2. Inferior or superior vena cava
3. Right atrium
4. Right Av (tricuspid) valve
5. Right ventricle
6. Pulmonary valve/semi lunar valve
7. Pulmonary artery
8. Lungs
9. Pulmonary veins
10. Left atrium
11. Bicuspid valve
12. Left ventricle
13. Aorta
14. Tissue

Question 9

What returns tissue fluid to the blood?

Answer 9

Lymphatic system

Question 10

Why is blood considered a tissue?

Answer 10

Connects the system and has functions

Question 11

Are erythrocytes true cells?

Answer 11

No, they have no nucleus or organelles.

Question 12

Why don’t arteries have valves like veins?

Answer 12

Arteries have a higher blood pressure than veins, therefore pushing blood through them more easily.

Question 13

Explain atherosclerosis and how it happens.

Answer 13

A disease caused by the build up of fat and plaque in an artery.
Damage to the endothelium (which is the tissue that the arteries are made of which are smooth) fat and plaque enter the walls, building up over time.

Question 14

What vessels carry blood to the heart? Away?

Answer 14

To: veins
Away: arteries

Question 15

What is the difference between the thickness of the atria and ventricles? Why?

Answer 15

Ventricles are thicker than atria. Blood needs more pressure to exit the heart than to enter it.

Question 16

Explain the difference between the walls of the left and right ventricles

Answer 16

The left ventricle has thicker muscles than those of the left ventricle. This is because the left ventricle pumps blood to the entire body, therefore needing more power to do so.

Question 17

Explain the heart sounds and what is happening.

Answer 17

lub
Here, the ventricles are contracting and the AV valves (tricuspid and bicuspid/mitral valves) are closing.
dub
Ventricles are relaxed and atria are contracting. The aortic and pulmonic (semi lunar) valves are closing.

Question 18

Explain systole and diastole

Answer 18

Diastole: period of the cardiac cycle where the ventricles are relaxed. Blood fills the ventricles.
Systole: period of the cardiac cycle where the ventricles are contracted. Blood is ejected from the ventricles.

Question 19

What is blood pressure?

Answer 19

The force exerted against the walls of the arteries as the heart pumps blood 120/80 is normal

Question 20

What is high blood pressure?

Answer 20

Hypertension

Stretches the arteries beyond a healthy limit

Question 21

Explain how the heart beats

Answer 21

1. The SA node depolarizes (gets excited) and fires
2. The atria contract
3. SA node sends message to AV node
4. AV node fires
5. Ventricles contract.

Question 22

Explain what an ECG is

Answer 22

Records electrical activity of the heart

Question 23

Explain the different parts of the ECG

Answer 23

• P wave represents excitation of the atria as a result of the SA node firing
• QRS wave represents ventricular excitation as the result of the AV node firing
  3. T wave is relaxation of the muscle

Question 24

Explain vasodilation and vasoconstriction

Answer 24

Vasodilation is when your blood vessels open up, allowing more blood flow to your muscles. (Heat, exercise, alcohol)
Vasoconstriction is when your blood vessels shrink. (Cold)

Question 25

Why is the systolic reading important?

Answer 25

Tells us the pressure exerted when the blood is being pumped to our body.

Question 26

What’s the difference between heart attacks and strokes?

Answer 26

Heart attacks: blood flow to heart is blocked

Strokes: blood flow to brain is blocked

Question 27

What is the function of the coronary arteries?

Answer 27

Provide blood to the heart muscle

Question 28

Explain sickle cell anemia

Answer 28

Shape of blood vessels changes, causing them to get stuck and reduce circulation of blood. Can cause dizziness, joint and muscle pain, etc.

Question 29

Explain coronary bypass surgery

Answer 29

A blocked or partially blocked artery is replaced by one from the arm, leg or chest to create a new pathway to the heart.