Chapter 9 - Adaptations for Transport in Animals

Question 1

What features are needed in transport systems in animals?

Answer 1

• A suitable medium in which to carry materials.
• A pump, such as the heart, for moving the blood.
• Valves to maintain the flow in one direction.

Question 2

What is the difference between an open and a close circulatory system and what organism has an open one?

Answer 2

• Open, blood doesn’t move around the body but bathes the tissues directly. E.g. insects.
• Closed, blood moves in blood vessels.

Question 3

What is the difference between a single and a double circulatory system?

Answer 3

• Single, blood moves through the heart once in its passage around the body.
• Double, the blood passes through the heart twice in its circuit around the body.

Question 4

What areas does the pulmonary and systemic circulation serve?

Answer 4

• Pulmonary, serves the lungs. The right side of the heart pumps deoxygenated blood to the lungs.
• Systemic, serves the body tissues. The left side of the heart pumps to oxygenated blood to the tissues.

Question 5

Why is double circulation more efficient than single circulation?

Answer 5

Because oxygenated blood can then be pumped around the body at a higher pressure.

Question 6

What is the structure of a blood vessel?

Answer 6

• Innermost endothelium layer, one cell thick, surrounded by the tunica intima.
• Tunica media, contains elastic fibres and smooth muscle.
• Tunica externa, contains collagen fibres, which resist overstretching.

Question 7

What are the 3 types of blood vessels?

Answer 7

• Arteries, carry blood away from the heart. Thick, muscular walls withstand the blood’s high pressure, derived from the heart.
• Capillaries, a vast network that penetrate all the tissues and organs of the body.
• Veins, have a larger diameter lumen and thinner walls. Contain valves to ensure flow in one direction and prevent back flow.

Question 8

What are the 3 stages of the cardiac cycle?

Answer 8

• Atrial systole, atrium walls contract and BP in the atria increases pushing the blood down into the ventricles.
• Ventricular systole, ventricle walls contract and increase the BP in the ventricles. Forces blood up through the semi-lunar valves out of the heart.
• Diastole, the ventricles relax. Volume of ventricles increase and so pressure falls.

Question 9

What node starts of the wave of excitation that causes the atria to contract?

Answer 9

The Sino-atrial node. Also known as the pacemaker.

Question 10

What does myogenic contraction mean?

Answer 10

It means it can contracts and relax rhythmically, of its own accord.

Question 11

What is the node that delays the transmission of the electrical impulse so the ventricles don’t contract immediately after the atria?

Answer 11

The Atrio-ventricular node (AVN).

Question 12

What causes the ventricles to contract?

Answer 12

The AVN passes the wave of excitation down the nerves of the bundle of His. This excitation is transmitted to Purkinje fibres in the ventricle walls, which carry it upwards through the muscles of the ventricle walls.

Question 13

On the electrocardiogram, what does the P wave represent?

Answer 13

P wave - shows the voltage charge generated by the SAN, associated with the contraction of the atria. The atria have less muscle than the ventricles so P waves are small.

Question 14

What does the QRS complex show?

Answer 14

Shows the contraction of the ventricles. They have more muscle than the atria and so the amplitude is bigger.

Question 15

What does the T wave show?

Answer 15

Shows the repolarisation of the ventricle muscles.

Question 16

What effect will atrial fibrillation have on the electrocardiogram?

Answer 16

The person will have a rapid heart rate and will lack a P wave.

Question 17

What will the electrocardiogram show in a person that’s had a heart attack?

Answer 17

They’ll have a wide QRS complex.

Question 18

How does blood return to the heart, despite the veins having a low Blood Pressure?

Answer 18

• The massaging effect of muscles around veins is enhanced.

- Valves in the veins prevent backflow.

Question 19

What is another name for a Red Blood Cell?

Answer 19

Erythrocytes.

Question 20

Why are they unusual and what gives them an advantage for their job?

Answer 20

• They’re biconcave discs which increases their Surface Area, meaning more oxygen can diffuse across the membrane.
• They have no nucleus meaning more room for haemoglobin.

Question 21

What does plasma contain?

Answer 21

• Around 90% water.
• Solutes such as glucose, aa, mineral ions etc.
• Waste products, such as urea.
• Hormones.
• Plasma proteins.

Question 22

What does the affinity refer to?

Answer 22

The degree to which 2 molecules are attracted to each other.

Question 23

What is cooperative binding?

Answer 23

The increasing ease with which haemoglobin binds its second and third oxygen molecules, as the conformation of the haemoglobin molecules change.

Question 24

What organisms have a higher affinity for oxygen compared to an adults haemoglobin?

Answer 24

• Llamas.
• Lugworms.
• Foetal haemoglobin.

Question 25

What is the Bohr effect?

Answer 25

The movement of the oxygen dissociation curve to the right at a higher partial pressure of CO2, because at a given oxygen partial pressure, haemoglobin has a lower affinity for oxygen.

Question 26

How does the production of Carbon Dioxide result in the release of oxygen from oxyhaemoglobin?

Answer 26

CO2 dissociatiates O2 in haemoglobin so the more CO2, the more O2 released.

Question 27

How are capillaries well adapted to allow the exchange of materials?

Answer 27

• They have thin, permeable walls.
• They provide a large surface area for exchange of materials.
• Blood flows very slow through capillaries allowing time for exchange of materials.

Question 28

What is the fluid that is forced through the capillary walls and bathes the tissues?

Answer 28

Tissue fluid.

Question 29

What are the conditions like at the arterial end of the capillary bed?

Answer 29

-Blood under under high pressure. High hydrostatic pressure pushes liquid outwards.

Question 30

What draws water back into the blood at a capillary?

Answer 30

The plasma has a low solute potential which tends to pull water back in by osmosis.

Question 31

What are the conditions like at the venous end of the capillary bed?

Answer 31

-The bloods hydrostatic pressure is now lower than the arterial end and the solute potential of the remaining plasma is now more negative. The osmotic force pulling water in is now stronger so water passes back into the capillaries by osmosis.

Question 32

What system deals with the remaining tissue fluid that hasn’t moved back into the capillaries?

Answer 32

Lymphatic system (Lymph nodes).