Circulatory System

Question 1

What are the properties of multi-cellular organisms e.g mammals that need a specialized transport system? - circulatory system

Answer 1

Low surface to volume ratio

Use to carry raw materials to their body cells

Question 2

What is the circulatory system made out of?

Answer 2

• Heart
• Blood vessels

Question 3

Where does the heart pump blood trough?

Answer 3

• Blood vessels (arteries, veins and capillaries) - to reach different parts of the body

Question 4

What do blood transport?

Answer 4

Respiratory gases

products of digestion

metabolic wastes

hormones round the body

Question 5

What are the two circuits of circulatory system?

Answer 5

• One takes blood from the heart to the lungs then back to heart
• Other loop takes blood around the rest of the body

Question 6

How does the heart has its own blood suppy?

Answer 6

Left and right coronary arteries

Question 7

What is this?

Answer 7

Aorta

oxygenated blood to body

Question 8

What is this?

Answer 8

Pulmonary artery

deoxygenated blood to lungs

Question 9

What is this?

Answer 9

Left coronary artery

Question 10

What is this?

Answer 10

Right coronary artery

Question 11

What is this?

Answer 11

Deoxygenated blood to heart

Question 12

Diagram of artery

Answer 12

Question 13

What is the function of arteries

Answer 13

Carry blood from the heart to the rest of the body

Question 14

How are arteries’s walls adapted for function?

Answer 14

The walls are thick and muscular

they have elastic tissue to stretch and recoil as the heart beats

this helps to maintain high pressure

Question 15

How is the inner lining (endothelium) folded is adapted for artery;’s function?

Answer 15

Allow the artery to stretch

this also maintains high pressure

Question 16

What do all arteries carry?

Answer 16

Oxygenated blood expect pulmonary arteries

take deoxygenated blood to the lungs

Question 17

What are arteries divide into smaller vessels called…?

Answer 17

Arterioles - form a network throughout the body

Question 18

What is the function of arterioles?

Answer 18

Blood is directed to different areas of demand in the body by muscles in arterioles

which contract to restrict or relax to allow full blood flow

Question 19

Diagram of vein

Answer 19

Question 20

What is the function of veins?

Answer 20

Take blood back to the heart under lower pressure

Question 21

Properties of lumen and muscle wall with veins

Answer 21

• Have a wider lumen than equivalent arteries
• Very little elastic or muscle tissue

Question 22

Why do veins have valves?

Answer 22

To stop the blood flowing backwards

Question 23

How is blood flow through veins is helped by?

Answer 23

Contraction of the body muscles surrounding them

Question 24

What do all veins carry?

Answer 24

Deoxygenated blood (oxygen used up by body cells)

expect pulmonary veins carry oxygenated blood to the heart from the lungs

Question 25

What do arterioles branch into?

Answer 25

Capillaries - smallest of blood vessels (e.g glucose and oxygen are exchanged between cells and capillaries so adapted to efficient diffusion)

Question 26

Diagram of capillaries

Answer 26

Question 27

Properties of capillaries

Answer 27

* Always found near cells in exchange tissues (e.g alveoli in lungs) - short diffusion pathway * Walls are also one cell thick - shortens diffusion pathway * A large number of capillaries so increase SA for exchange * The network of capillaries in tissues are called capillary beds

Question 28

What is tissue fluid?

Answer 28

Fluid that surrounds cells in tissues

Question 29

What is tissue fluid made up of?

Answer 29

Small molecules that leave the blood plasma e.g O2 , water and nutrients

Question 30

What does tissue fluid not contain?

Answer 30

Red blood cells or big proteins -they are too large to be pushed out of the capillary walls

Question 31

What do cells take in from tissue fluid?

Answer 31

Oxygen and nutrients release metabolic waste into it

Question 32

In capillary bed , the substances move in and out of the capillaries into tissue fluid by what?

Answer 32

Pressure filtration

Question 33

Steps of formation of tissue fluid

Answer 33

* At the start of capillary bed (nearest arteries), the hydrostatic pressure inside capillaries is greater than in tissue fluid * The difference means outward pressure forces fluid out of capillaries and into spaces around cells forming tissue fluid * Water and smaller molecules forced out e.g 02, Na+ and glucose * Large molecules stay inside capillary e.g proteins

Question 34

Return of tissue fluid

Answer 34

* As fluid leaves , hydrostatic pressure reduces capillaries - so pressure lower at venule end of capillary bed (nearest to veins) * Water potential is lower than in tissue fluid due to the increasing concentration of plasma proteins (don't leave the capillary bed) * Some water re-enters the capillaries from tissue fluid to venule end by osmosis * Hydrostatic pressure drop in capillary so water moves down pressure gradient

Question 35

What happens to the excess tissue fluid?

Answer 35

Drains into the lymphatic system (network of tubes -act as frain) transport this excess tissue fluid and puts back into circulatory system

Question 36

Name all blood vessels entering and leaving the heart

Answer 36

* Entering * Vena Cava * Pulmonary veins * Exiting * Aorta * Pulmonary arteries

Question 37

List four types of blood vessel

Answer 37

* Arteries * artieroles * Veins * capillaries

Question 38

Explain why water returns to capillary at the venule end of the capillary bed

Answer 38

Due to fluid loss Increasing concentration of plasma proteins (don't leave the capillaries) water potential at the venule end of capillary bed is lower than water potential in tissue fluid Some water re-enters the capillaries from tissue fluid at the venule end by osmosis

Question 39

Describe two structural features of an artery and explain how each feature relates to function

Answer 39

* e.g elastic tissue in walls - stretch and recoil as heartbeats to maintain high pressure * Inner lining (endothelium) is folded so that artery can expand when the heartbeat causes a surge of blood

Question 40

At the arteriole end of a capillary bed the hydrostatic pressure is 5.1kPa in a capillary and 0.13 kPa in the space around the cells Explain the effect this has no movement of fluid between capillary and cell space

Answer 40

The hydrostatic pressure is greater than hydrostatic pressure around cells So fluid moves out of capillary into spaces of the cells