Circulatory System

Question 1

What is the structure and function of Red Blood Cells?

Answer 1

• Structure:
  • Biconcave shape, maximises surface area
  • Small and flexible to fit through narrow blood vessels
  • No nucleus to contain more haemoglobin (protein)
• Function:
  • Delivers oxygen
  • Carry out waste gases (Co2)

Question 2

What is the structure and function of White Blood Cells?

Answer 2

• Structure:
  • Various structures e.g. granular cytoplasm, large nucelus, lobed nucelus
• Function:
  • Defends body against disease, makes antibodies to initiate immune response

Question 3

What is the structure and function of Platelets?

Answer 3

• Structure:
  • Fragments of cells
  • Proteins attached to surface (allow sticking together during clotting)
• Function:
  • Helps body repair by stopping the bleeding after illness or injury
  • Makes up the rest of blood

Question 4

What is the structure and function of Plasma?

Answer 4

• Structure:
  • Clear, pale straw coloured liquid
• Function:
  • Liquid part of the blood
  • Hormones, carbon dioxide and waste transport
  • Makes up over half the volume of blood

Question 5

Describe the Double Circulatory System

Answer 5

Systemic Circulation:

1) Lungs: Collects oxygen, diffuses it into the blood
2) Pulmonary Vein: Pumps oxygenated blood into the heart
3) Left Atrium: Enters here
4) Bicuspid Valve: Oxygenated blood travels through and stops blood flowing backwards in the cycle
5) Left Ventricle: Contracts to push blood up and out
6) Aorta: sends oxygenated blood to the rest of the body
7) Body tissues: Oxygen becomes deoxygenated

Pulmonary Circulation:

8) Vena cava: Pumps deoxygenated blood into the heart
9) Right Atrium: Enters here
10) Tricuspid Valve: Deoxygenated blood travels through and stops blood flowing backwards in the cycle
11) Right Ventricle: Contracts to push blood up and out
12) Pulmonary Artery: Pumps blood back to the lungs to become oxygenated

Cycle Repeats

Question 6

What are the two Blood Circulation Systems?

Answer 6

• Pulmonary

- Systemic

Question 7

What are the 4 layers of the heart?

Answer 7

MEEP

1) Endocardium (Epithelial inner lining)
2) Myocardium (Muscle of the heart)
3) Epicardium (Muscle covering)
4) Pericardium (Outer layer of heart)

Question 8

What causes the heart to beat?

Answer 8

• Sinoatrial Node: Natural pacemaker, causes impulse to travel through atria, causes blood to contract and force blood into ventricles
• Atrioventricular Node: Detects impulse travelling through atria, redirects to bundle of His, causes a delay, slows the spread of electrical impulse over the heart allowing atria to contract before the ventricles
• Bundle of His: Group of fibres where impulse travels through to base of ventricles
• Purkinje fibres: Act like neurons, causes ventricles to contract

Question 9

What is the structure and function of Arteries?

Answer 9

• Structure:
  • Thick walls to withstand high pressure
  • Contains smooth muscle
• Function:
  • Constricts / Dilates to allow greater or lesser flow of blood
  • Carries blood away from the heart

Question 10

What is the structure and function of Veins?

Answer 10

• Structure:
  • Large
  • Thin-walled as not a lot of pressure
  • Valves to stop blood flow in wrong direction
• Function:
  • Carries blood into the heart

Question 11

What are Capillaries?

Answer 11

• Found within body tissues

- When blood vessels become very thin-walled and smaller to allow oxygen exchange, these are called capillaries

Question 12

What are some functions of Blood?

Answer 12

• To carry oxygen to and carbon dioxide away from tissues
• To carry digestive food products to tissues
• To supply water to tissues
• To carry waste away from tissues and into the kidneys for excretion
• Helps regulate body temperature, distributes heat throughout body
• Stops haemorrhaging by blood clotting
• Transports hormones and enzymes
• Protects body against infection, transports antitoxins and antibodies
• Assist in maintenance of correct pH of tissues