Multicellular Organisms - The Heart

Question 1

Describe the flow of blood through the LEFT SIDE of the heart

Answer 1

1. Oxygenated blood returns to heart through pulmonary vein, then left atrium
2. Atrium contracts → blood flows from left atrium to left ventricle
3. Left ventricle contracts → blood leaves heart through aorta to rest of body.
4. Aorta branches into arteries then arterioles and capillaries for gas exchange.
5. The coronary artery (first aorta branch) supplies the heart muscle. Blood returns to the heart through veins.

Question 2

Describe the flow of blood through the RIGHT SIDE of the heart

Answer 2

1. Blood circulated around the body? = deoxygenated → high in CO2, low in O2
2. Blood enters the heart through the vena cava, then right atrium
3. Atrium contracts → blood flows from right atrium to right ventricle
4. Right ventricle contracts → blood leaves heart through pulmonary artery to go to lungs, where CO2 is lost as waste and haemoglobin converts to oxyhaemoglobin

Question 3

Describe the following and discuss their features
* veins
* arteries
* capillaries

Answer 3

ARTERY
* Thick muscular wall, narrow central channel
* Carries blood at a high pressure away from heart

VEIN
* Thinner muscular wall than arteries, wider central channel
* Carries blood at a low pressure back to the heart

CAPILLARIES
* Large surface area, thin muscular walls (one cell thick)
* Facilitates exchanges of materials between blood and living tissues.

Question 4

Describe the role of the following:
* Right atria
* Right ventricle

Answer 4

• Collects deoxygenated blood from vena cava, passes it to right ventricle
• Collects deoxygenated blood from right atria, pumps it through pulmonary artery

Question 5

Describe the role of the following:
* Left atria
* Left ventricle

Answer 5

• Collects oxygenated blood from pulmonary vein, passes it to left ventricle
• Collects oxygenated blood from left atria, pumps it through aorta

Question 6

Describe the role of the following:
* Coronary artery
* Valves

Answer 6

• Accepts oxygenated blood pumped at high pressure by left ventricle and distributes to heart muscle
• Prevents backflow of blood

Question 7

What is the role of the cardiovascular system?

Answer 7

• Transporting oxygen, nutrients and waste throughout the body.
• Consists of the blood vessels, blood and heart

Question 8

Describe capillary networks

Answer 8

• Artery divides into smaller vessels, then into a dense network of capillaries.
• They present a large surface area and are in close contact with living cells in tissues and organs