Blood Vessels

Question 1

What is an open circulatory system?

Answer 1

One in which the blood is not held in vessels instead the organisms blood fluid circulates through the body cavity so that the tissues and cells are bathed directly in blood.

Question 2

What is an arteriole?

Answer 2

Small blood vessel that distributes blood from an artery to the capillaries.

Question 3

What are venules?

Answer 3

Small blood vessels that collect blood from capillaries and lead into the veins

Question 4

Instead of a heart in insects what is there?

Answer 4

A muscular tube that lies just under the dorsal (upper) surface of the body.

Question 5

What are the pores in an insect called?

Answer 5

Ostia

Question 6

What is the method that blood in an insect is pumped towards the head?

Answer 6

Peristalsis

Question 7

What happens when the blood is pumped towards the forward end of the head?

Answer 7

The blood simply pores into the body cavity

Question 8

How do large insects like locusts differ?

Answer 8

They have tubes at the end of their heart that direct blood towards more important muscles such as the keg and wing muscles

Question 9

Why must small insects be continually moving?

Answer 9

If they have no heart the way their blood is ‘pumped’ around is through movement.

Question 10

What are the disadvantages of open circulatory systems?

Answer 10

Blood pressure is low and blood flow is slow

Circulation of blood may be affected by movement or lack of

Question 11

What is meant by a closed circulatory system?

Answer 11

The blood stays entirely in vessels.

Question 12

What is the separate fluid that bathes cells called in a closed circulatory system?

Answer 12

Tissue fluid

Question 13

What are the advantages of an open circulatory system?

Answer 13

Higher pressure
More rapid delivery of oxygen and nutrients
More rapid removal of wastes
Transport is independent of body movement

Question 14

What is the inner layer of blood vessels called?

Answer 14

Endothelium

Question 15

Why must artery walls be thick?

Answer 15

To withstand the higher pressure

Question 16

What are the three layers of the arteries and what do they do?

Answer 16

Inner layer (tunica intima) thin layer of elastic tissue allows the walls to stretch and recoil
Middle layer (tunica media) thick layer of smooth muscle
Outer layer (tunica adventitia) thick layer of collagen and elastic tissue. Provides strength to withstand pressure

Question 17

What do arteriole walls contain to restrict the diameter of the arteriole?

Answer 17

Smooth muscle

Question 18

Why is the constriction of blood flow important with arteriole?

Answer 18

Able to direct blood to regions of the body requiring more oxygen

Question 19

Capillaries have very thin walls.

What do their single thin layer consist of?

Answer 19

Flattened endothelial cells

Question 20

Why are capillaries so thin?

Answer 20

To reduce the diffusion distance for the materials being exchanged

Question 21

Capillary walls can be described as leaky. What does this allow?

Answer 21

Blood plasma and dissolved substances to leave the blood

Question 22

Where does the blood flow into after capillaries?

Answer 22

Venules

Question 23

What do venules consist of?

Answer 23

Thin layers of muscle and elastic tissue and a thin outer layer of collagen

Question 24

Why do veins contain valves?

Answer 24

To stop blood from flowing in the opposite direction

Question 25

Veins can be flattened by surrounding skeletal muscle tissue what does this mean?

Answer 25

It means that contraction of muscles can cause blood to be pumped back to the heart in the direction that the valves allow

Question 26

Why is a veins lumen large?

Answer 26

To ease the flow of blood

Question 27

What do arteries do that veins don’t?

Answer 27

Constrict and recoil