Chapter 1: Lifestyle, Health And Risk

Question 1

Mass flow system define

Answer 1

A system that transports substances in bulk as a result of a pressure difference between two points

Question 2

Mass flow system requirements

Answer 2

Circulatory fluid
Contracting pump to move fluid
Tubes through which fluid can circulate

Large quantities of materials moved
Fast, over a long distance

Question 3

Mass flow systems

Answer 3

CIRCULATORY- blood- heart and contractile blood vessels (artery mainly)

DIGESTIVE - food and water - muscle surrounding intestines

RESPIRATORY - air or water - intercostal muscles and diaphragm

LYMPHATIC - lymph- contraction of skeletal muscles

Question 4

Open circulatory system

Answer 4

Blood is not contained in blood vessels

Most Arthropods and some molluscs
Blood pumped into body cavities by heart

Heart relaxes, blood drawn back from cavities into heart through open valves

Blood= haemolyph (mixed with tissue fluid)

Question 5

Closed circulatory system

Answer 5

Blood enclosed in blood system

-can be pumped under high pressure

Question 6

Closed circulatory system: open

Answer 6

Blood passes through heart once as it circulates the body

• fish
• low pressure
• arrangement of organs are series

Question 7

Closed circulatory system: double

Answer 7

Blood passes through heart twice as it circulates the body

Maximum gas exchange to cells as the concentration gradient is kept high

Oxygenated/ deoxygenated blood not mixed

Each circuit can have different pressure

• mammals and birds, high pressure in systemic (circuit to whole body), low pressure in pulmonary
• arrangement of organs are parallel

Question 8

Closed circulatory system: amphibians

Answer 8

3 heart chambers, third circuit brings deoxygenated blood to lungs and skin for gas exchange

Double circulation

But mixing of nooo in ventricles- reduces efficiency of oxygenation

Tired, no sustained movement as lack O2
High pressure pushes blood to lungs/body

Question 9

Heart: location

Answer 9

Middle region of thorax

Apex points left

Question 10

Heart: protection

Answer 10

Pericardium (sac of connective tissue)

-keeps pressure up by limiting relaxation

Question 11

Heart: Valves

Answer 11

Ensures unidirectional blood flow (prevents back flow)

Question 12

Heart:Tendinous chords

Answer 12

Stops valves from inverting

Made of collagen- not elastic, tough fibrous protein: strong/ durable

Question 13

Heart: muscle

Answer 13

Pericardium- epicardium- myocardium- endocardium

Branch of coronary artery

Question 14

Why do animals have heart & circulation?

Answer 14

DIFFUSION is not fast enough in larger organisms as distances are greater than a few nanometers

Multicellular
Thermoregulation, hormones
Metabolically active- warm blooded

Question 15

Artery

Answer 15

0.1-10mm 
•narrow lumen 
•thicker walls 
•more collagen, elastic fibres and smooth muscle (stretches less, more recoil) 
•no valves

Question 16

Vein

Answer 16

10-15mm 
•wide lumen 
• thinner walls 
• less collagen, elastic fibres and smooth muscle 
•no valves

Question 17

Capillary

Answer 17

10 micro metres diameter
•walls 1 cell thick
•single layer endothelial cells
•no valves

Question 18

Collagen and elastic fibres

Answer 18

Collagen tough fibrous protein- strong/ durable

Elastic fibres- allows stretch and recoil

Question 19

arteries: stretch and elastic recoil

Systole and diastole

Answer 19

Systole- stretch
•blood forced into arteries as heart contracts
• elastic walls stretch to accommodate blood

Diastole- elastic recoil
•heart relaxes, walls recoil behind blood due to elasticity-> helping push blood forward

Question 20

Veins: valves

Answer 20

Skeletal muscles contract during movement of limbs and breathing
-blood pushed towards heart through opened valves

Low pressure in thorax when breathing in helps draw blood back into heart from veins
-valves close preventing back flow

Question 21

Capillar: networks

Answer 21

Venice and arteriole

Network lies close to every cell- rapid diffusion between blood and cells