Heart Structure and Function 1.1-1.4, 1.17 and CP1

Question 1

Why do many animals require a mass transport system?

Answer 1

Diffusion across outer membranes would be too slow because of the large distances substances would have to travel to reach cells so they have mass transport systems

Question 2

What do mass transport systems do?

Answer 2

• They carry raw materials (glucose and oxygen) from specialised exchange organs (lungs) to body cells
• Remove metabolic waste (carbon dioxide)

Question 3

What is the mass transport system in mammals?

Answer 3

Circulatory system which is used to pump blood around the body

Question 4

What is the main function of water in terms of blood?

Answer 4

Water is a solvent, allowing substances to dissolve in it.

Question 5

Why is it important that water acts as a solvent?

Answer 5

• Many important reactions take place in solution

- Easily transport materials quickly

Question 6

Why can water be described as a dipolar molecule?

Answer 6

It has a partial negative charge on one side (oxygen) and a partial positive charge on the other side (hydrogens)

Question 7

What is a water molecule made from?

Answer 7

One atom of oxygen joined to two atoms of hydrogen by share electrons

Question 8

Why are the hydrogen atoms slightly positive?

Answer 8

The shared negative hydrogen electrons are pulled towards the oxygen atom causing the other side to be slightly positive

Question 9

Why is the oxygen atom slightly negative?

Answer 9

The unshared negative electrons give it a slight negative charge

Question 10

What is hydrogen bonding?

Answer 10

Negatively charged oxygen atoms attract positively charged hydrogen atoms of other water molecules

Question 11

What is cohesion?

Answer 11

The attraction between molecules of the same type

Question 12

Why is cohesion good for transportation?

Answer 12

Water molecules stick together due to their dipolar nature, helping water to flow

Question 13

What is an ionic substance? + eg

Answer 13

A substance made from ONE POSITIVELY CHARGED molecule and ONE NEGATIVELY CHARGED molecule
Salt is made from a positive sodium ion and a negative chloride ion

Question 14

What property of water allows ions to dissolve and explain

Answer 14

Good solvent
Slightly positive end of water molecule will be attracted to negative ion and slightly negative end of water molecule will be attracted to positive ion = ions totally surrounded by water = dissolve

Question 15

Which side of the heart pumps oxygenated blood to the body?

Answer 15

Left side

Question 16

Which side of the heart pumps deoxygenated blood to the lungs?

Answer 16

Right side

Question 17

What can you observe from external examination of the heart?

Answer 17

Right and left atria
Right and left ventricles
Coronary arteries

Question 18

Are atria or ventricle walls thicker?

Answer 18

Ventricle walls

Question 19

Is the left or right ventricle thicker?

Answer 19

Left

Question 20

Why is the left ventricle thicker than the right?

Answer 20

The left ventricle contains lots of muscle because it needs to contract to pump blood around the body under high pressure
The right ventricle only pumps deoxygenated blood to the lungs

Question 21

Why do ventricles have thicker walls than the atria?

Answer 21

Ventricles have to pump the blood out of heart

Atria just have to pump blood into ventricles

Question 22

Where are the atrioventricular valves found?

Answer 22

Between the atria and the ventricles

Question 23

Where are semi-lunar valves found?

Answer 23

Between the ventricles and the pulmonary artery/aorta

Question 24

What is the purpose of valves?

Answer 24

Allow blood flow to happen in one direction
If pressure behind valve is greater then valve will open, if pressure is greater in front of valve then it will be forced shut

Question 25

Describe the structure + function of arteries

Answer 25

Arteries carry blood away from the heart to the rest of the body

• Thick walled with elastic tissue to cope with high pressure
• Lined with muscle
• Inner lining (endothelium) is folded to allow it to expand
• Narrow lumen

Question 26

Describe the structure + function of veins

Answer 26

Veins carry blood back to the heart from the body

• Little elastic tissue or muscle due to lower pressure
• Contain valves to prevent back flow of blood
• Blood flow is aided by contraction of skeletal muscles
• Wide lumen

Question 27

Describe the structure + function of capillaries

Answer 27

Where metabolic exchange occurs between cells and capillaries

• Network of capillaries to increase surface area for exchange
• Endothelium is one cell thick to speed up diffusion

Question 28

Describe atrial systole

Answer 28

The atria contract = decreased volume of chamber = increases pressure = pushes blood into ventricles = slightly increase in ventricular pressure

Question 29

Describe ventricular systole

Answer 29

The atria relax and ventricles contract = volume of chamber decreases and pressure increases = AV valves shut = pressure higher in ventricles than aorta/pulmonary artery = SL valves open

Question 30

Describe diastole

Answer 30

Ventricles and atria relax = high pressure in aorta/pulmonary artery closes valves = atria fill again due to higher pressure in vena cava and pulmonary vein

Question 31

Why are daphnia suitable for measuring heart rate?

Answer 31

They are transparent and easily observed under a microscope

Question 32

Describe how you would investigate the effect of caffeine in the heart rate of daphnia?

Answer 32

1) Make a range of different concentrations of caffeine (including control)
2) Transfer ONE daphnia onto a slide and use a pipette to add a few drops of caffeine solution - wait for 5 mins for daphnia to acclimatise
3) Place the slide on the stage of a light microscope
4) Count number of heartbeats in 20 seconds and multiply by 3
5) Repeat ten times using same concentration of caffeine but different daphnia to get an average
6) Repeat for other concentrations and compare results

Question 33

What type of correlation is there between caffeine and heart rate?

Answer 33

As caffeine concentration increase, heart rate increases

Question 34

What are some ethical issues about using invertebrate such as daphnia?

Answer 34

• Cannot give consent
• Subject to pain
• Causes distress eg. deprivation of food

Question 35

Why use invertebrate over vertebrate?

Answer 35

Simpler organisms with a much less sophisticated nervous system = less pain