Unit 3- Cardiovascular

Question 1

Why do we need a circulatory system + give 2 features.

Answer 1

• we have a small s.a.:vol
• ∴ diffusion x sufficient
  1. exchange surfaces- 🫁
  2. transport system- 🫀

Question 2

Why do we need a circulatory system + give 2 features.

Answer 2

• we have a small s.a.:vol
• ∴ diffusion x sufficient
  1. exchange surfaces- 🫁
  2. transport system- 🫀

Question 3

Features of an effective transport system

Answer 3

1. suitable medium- eg. blood is water-based
2. closed transport network of tubular vessels (capillaries, veins, arteries)
3. mechanism for moving medium within vessels
   - 🐾- muscular heart
   - 🌿- transpiration stream

Question 4

State the 2 main parts to the mammalian double pump

Answer 4

1. pulmonary system: deoxygenated blood to the lungs
2. systemic system: oxygenated blood depressurised + sent around the body

Question 5

Where is the heart located?

Answer 5

• enclosed by pericardium (between 2 lungs)
• pericardial fluid secreted–> aid movement
• protects ❤️ from overexpansion

Question 6

What are the walls of the ❤️ made up of?

Answer 6

Cardiac muscle- myocardium
- never tires unless lack of O2

Question 7

Suggest why it is important to prevent mixing of the blood in the 2 sides of the heart.

Answer 7

• only partially oxygenated blood–> tissues + lungs
• ↓ O2 supply
• ↓ diffusion gradient in lungs
• ↓ rate of O2 uptake

Question 8

Explain why blood pressure fluctuates up and down between the aorta and small arteries.

Answer 8

• contraction of left ventricle–> distension of aorta
• elastic layer- recoil –> series of pulses of ↑ Pa ∵ ventricular contraction

Question 9

Explain why the rate of blod flow decreases between the aorta and capillaries.

Answer 9

• ↑ area of blood vessel wall
• ↑ frictional resistance