Module 3: Transport in Animals

Question 1

What are the 3 main types of blood vessels?

Answer 1

arteries
veins
capillaries

Question 2

What do arteries do?

What structures do they contain?

Answer 2

thy carry oxygenated blood away from the heart to the rest of the body/respiring tissues

smooth muscle
elastic tissue
collagen
smooth endothelium
lumen

Question 3

Do arteries have a narrow/wide lumen?
Why?

Answer 3

they have a narrow lumen so they are able to pump blood at a higher pressure

Question 4

Why do arteries need to pump blood at higher pressure?

Answer 4

because they have to transport blood to the rest of the body very quickly

Question 5

Why do arteries contain thick elastic walls and smooth muscle walls?

What is the role of collagen?

Answer 5

elastic-enables them to stretch to withstand high pressure
smooth muscle-ensures the vessels don’t burst under high pressure and helps to regulate the pressure when blood reaches arterioles

helps them withstand high pressure

Question 6

What is the role of the smooth endothelium in arteries and veins?

Answer 6

to reduce friction and ease blood flow

Question 7

What are the names of the three layers of smooth muscle?

Answer 7

Tunica intima
Tunica media
Tunica externa

Question 8

What do veins do ?

What structures do they contain?

Answer 8

they carry deoxygenated blood towards the heart

the same as arteries but have a wider lumen and thinner layers of tissue

Question 9

What do veins contain that arteries don’t and why?

Answer 9

valves , because blood is pumped at a lower pressure they ensure there is no backflow of blood

Question 10

Why do veins have a wider lumen than arteries?
2

Answer 10

to maximise the volume of blood being carried to the heart
they don’t need to carry blood at high pressure

Question 11

Why do veins contain thinner layers of smooth muscle and elastic tissue?

Answer 11

because they arent carrying blood at high pressure so dont need to stretch and recoil

Question 12

What do capillaries do ?
What structures do they contain?

Answer 12

they are the site of metabolic exchange between cells and the bloodstream

they are only 1 cell thick
narrow lumen
smooth endothelium

Question 13

Why do capillaries have a narrow lumen and a small diameter?

Answer 13

lumen-enables them to fit into small spaces throughout body tissues
diameter-creates a short diffusion pathway which increases efficiency as an exchange surface

Question 14

What is the order of blood flow around the body?
(excluding the lungs)

Answer 14

heart
arteries
arterioles
capillaries
venules
veins
heart

Question 15

What is the composition of blood and what does each component do ?

Answer 15

55% plasma -carries dissolved solutes
45% erthrocytes (RBC) -carry oxygen
less than 1% leukocytes(WBC) and platelets-attack pathogens and clot blood

Question 16

What is tissue fluid?

What is its role?

Answer 16

a liquid containing dissolved solutes such as amino acids , hormones , glucose etc

to supply bodily tissues with the essential solutes in exchange for waste products such as carbon dioxide and urea
-therefore it enables exchange of substances between blood and cells

Question 17

What is hydrostatic pressure and what does it do?
What is oncotic pressure?

What are fenestrations?

Answer 17

pressure created when blood is pumped along arteries , arterioles and capillaries
it forces blood fluid in the plasma out of the capillaries through fenestrations

A type of osmotic pressure that leads to a tendency for water to flow into the capillaries due to the presence of large proteins in blood that lower water potential

tiny gaps within capillary walls

Question 18

What is the name given to the process of these substances leaving the fenestrations?

Answer 18

ultrafiltration

Question 19

What happens at the arterial end of capillaries?
Which type of pressure is greater?

What happens at the venous end of capillaries and what type of pressure is greater?

Answer 19

tissue fluid moves out of capillaries into extracellular space as hydrostatic pressure is greater ( more neg ) than osmotic pressure

tissue fluid moves into capillaries as osmotic pressure is greater ( more neg ) than hydrostatic pressure

Question 20

How many different types of circulatory system are there? What are they?

Answer 20

4
Open , closed , single , double

Question 21

Why do multicellular organisms need transport systems?
4

Answer 21

-they are much larger
-they have a much higher metabolic rate so require more substances and faster
-they have a small SA:V ratio so cant rely on diffusion
-we need to transport molecules made in one place to where they are needed in the body

Question 22

What is the difference between and open/closed system ?

In a closed system , does the transport medium come directly into contact with bodily cells , and does this happen in an open system either?

Answer 22

open-fluid isnt always contained in vessels
closed-fluid is always contained in vessels

closed-no
open-yes , this is where exchange takes place

Question 23

What do all transport systems contain?
3

Answer 23

-a transport medium
-vessels that carry this medium
-a pumping mechanism to move the fluid around the system

Question 24

How do single and double circulatory systems differ?

2 for each type

Answer 24

single systems-the heart has 2 chambers so blood passes through the heart once for a complete circuit
double system-the heart has 4 chambers so blood passes through the heart twice for a complete circuit of the body

Question 25

In terms of pressure and speed of blood flow , what is the difference between open and closed circulatory systems?

Answer 25

open-blood travels at a low speed and is pumped at low pressure
closed-blood travels relatively quickly and is pumped under greater pressure

Question 26

Is tissue fluid or blood more negative in terms of water potential?
What does this result in?

Answer 26

blood is more negative as it contains more solutes
tissue fluid is positive compared to blood which causes water to move down the water potential gradient from tissue fluid to blood by osmosis

Question 27

What happens to remaining tissue fluid that isn’t pushed back into capillaries?

Answer 27

it is carried back by the lymphatic system

Question 28

What does the lymphatic system contain?
What is the composition of this substance?
Explain why it has this composition

Answer 28

lymph fluid
its similar in content to tissue fluid but contains less oxygen and nutrients as its main purpose is to carry waste products
it also contains fatty acids that’ve been absorbed from the villi of the small intestine

Question 29

Name two other structures present in the lymphatic system and explain their purpose…

Answer 29

lymph nodes-to filter out bacteria and foreign material from the lymph fluid
lymphocytes-produce antibodies that destroy these invaders