Unit 1: Arteries, Veins & Capillaries

Question 1

Flow chart for blood circulation

Answer 1

Heart—> arteries —> capillaries—> veins —> heart

Question 2

Fill in the blank:

Blood pressure _________ as blood moves away from the heart

Answer 2

Decreases

Question 3

What carries blood away from the heart

Answer 3

Arteries

Question 4

What carries blood back to the heart

Answer 4

Veins

Question 5

What do arteries contain

Answer 5

• Outer layer of connective tissue with elastic fibers
• thick smooth muscle with elastic fibers
• inner endothelial lining
• narrow lumen

Question 6

Why do the elastic walls of arteries stretch & recoil

Answer 6

To accommodate the surge of blood after each heartbeat

Question 7

What do the elastic fibers do in an artery

Answer 7

Stretch & recoil

Question 8

What is it called when The smooth muscle in arteries contract

Answer 8

Vascoconstrict

Question 9

What is it called when the smooth muscle in arteries dilates

Answer 9

Vasodilation

Question 10

Why does the smooth muscle in arteries vasoconstrict and vasodilate

Answer 10

To control blood flow - it dilates where we need blood the most and restricts other areas

Question 11

What do veins contain

Answer 11

• outer layer of connective tissues with elastic fibers
• inner endothelial lining
• thin smooth muscle
• wide lumen
• valves

Question 12

Why do veins have valves

Answer 12

To prevent the back flow of blood

Question 13

What does the wide lumen do in veins

Answer 13

Reduces resistance

Question 14

Why do veins have thinner walls

Answer 14

Due to blood being carried back to heart at low pressure

Question 15

How thick are capillaries

Answer 15

1 cell thick

Question 16

Do capillaries have thick or thin walls

Answer 16

They have thin walls

Question 17

What can capillaries allow

Answer 17

Exchange of substances with tissues through their thin walls

Question 18

What happens during pressure filtration

Answer 18

• blood is at high pressure arriving from the arteriolar to the capillaries
• This differenace causes much of the plasma to be forced through thin walls into the fluid surrounding the cells.

This fluid is now called tissue fluid.

Question 19

What is the difference between blood plasma and tissue fluid

Answer 19

Tissue fluid does not contain any plasma proteins beacuse they don’t fit

Question 20

What happens after pressure filtration

Answer 20

Diffusion of soluble food , oxygen and useful ions into nearby cells such as carbon dioxide & urea diffuse out into tissue fluid.

Much of the tissue fluid then returns to capillaries by osmosis.

Question 21

What happens to the tissue fluid that does not get absorbed back into the blood

Answer 21

It gets absorbed into thin walled lymphatic vessels which are found in connective tissue.

Question 22

What is the tissue fluid called that gets absorbed by the lymphatic vessels

Answer 22

Lymph

Question 23

How does the lymphatic system work

Answer 23

No pump like heart - Flow of lymph is by vessels being periodically compressed when muscles contract.

Question 24

Lymphatic system flow chart

Answer 24

Blood arrives at capillary at - High pressure
Plasma ⬇️
—————Pressure filtration
I ⬇️
I Diffusion
Tissue I ⬇️
Fluid I—————-Osmosis
⬇️
Absorbed into lympathic system
Lymph