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Bio 1: Lifestyle, Health and Risk > Blood Vessels > Flashcards

Flashcards in Blood Vessels Deck (27)
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1

What direction do arteries always pump blood in?

Away from the heart

2

What direction do veins always pump blood in?

Towards the heart

3

List the properties of arteries

- Thick walls of muscle
- Folded endothelium
- Narrow lumen
- No valves
- Elastic fibre tissue

4

Why do arteries have thicker muscle walls? 2

- Withstand high pressure
- Can widen/contract [vasodilation, vasoconstriction] to change blood flow

5

Why do arteries have a narrow lumen?

Extra support from lumen not needed as already has thick walls and high blood pressure

6

Why do arteries have no valves?

High pressure and gravity prevents backflow

7

Why do arteries have elastic tissue?

Arteries can recoil behind the blood to push it forward - maintains smooth pressure

8

Why do arteries have a folded endothelium?

Allows artery to expand and cope with high pressure

9

List the properties of a vein

- Thinner walls of muscle
- Wide lumen
- Valves
- Less elastic tissue

10

Why do veins have thinner walls of muscle? 4

- Lower pressure
- To accommodate wide lumen
- They don't undergo vasoconstriction/dilation
- Veins close to skeletal muscles, when muscles contract they compress vein walls, pumping blood forwards

11

Why do veins have a wide lumen?

Ensures pressure stays low

12

Why do veins have less elastic tissue?

Lower pressure

13

Why do veins have valves?

Lower pressure risks backflow of blood

14

How do valves work?

- Higher pressure behind valve: its forced open
- Higher pressure in front of valve: forced shut

15

What is the purpose of valves?

To ensure blood flows in one direction, preventing backflow

16

What are the 3 types of blood vessel?

- Artery
- Vein
- Capillary

17

Where are capillaries?

They surround all cells and exchange substances e.g glucose

18

List the properties of the capillaries

- Very thin walls
- Forms capillary beds [network of capillaries]
- Narrow lumen

19

How thin are capillary walls?

1 single layer of endothelial cells

20

Why do capillaries? have very thin walls

Short diffusion distance

21

Why do capillaries form capillary beds/networks?

Increased surface area for diffusion

22

Why do capillaries have a narrow lumen?

- Forces blood to slow down due to friction against wall
- More time for diffusion

23

What are all blood vessels made of?

Collagen

24

What is collagen?

Tough fibrous protein

25

What does collagen do for blood vessels?

Makes them strong and durable

26

What do all blood vessels have?

Smooth endothelium

27

What does a smooth endothelium do in blood vessels?

Reduce friction