3.3 Mass transport in animals

Question 1

Cardiac muscle is myogenic, what does myogenic mean ?

Answer 1

It can contract and relax without nervous or hormonal stimulation

Question 2

What is formed when oxygen binds to haemoglobin ?

Answer 2

Oxyhaemaglobin

Question 3

What is dissociation ?

Answer 3

The process by which oxygen is released from oxyhemoglobin to tissues in the body

Question 4

How many polypeptide chains make up haemoglobin ?

Answer 4

4, so it has a quaternary structure

Question 5

What is oxygen partial pressure ?

Answer 5

The concentration of oxygen in cells

Question 6

If partial pressure is high what does this mean for haemoglobin’s affinity for oxygen ?

Answer 6

If pO2 is high, haemoglobin has a high affinity for oxygen and oxygen binds to haemoglobin

Question 7

If partial pressure is low what does this mean for haemoglobin’s affinity for oxygen ?

Answer 7

If pO2 is low, haemoglobin has a low affinity for oxygen and oxygen dissociates from haemoglobin

Question 8

What is association ?

Answer 8

Oxygen binding to haemoglobin

Question 9

What does a dissociation curve show ?

Answer 9

The relationship between the percentage saturation of haemoglobin and oxygen partial pressure of the surrounding tissues

Question 10

What is the typical shape of an oxygen, haemoglobin dissociation curve ?

Answer 10

S shape

Question 11

What is the Bohr effect ?

Answer 11

When the partial pressure of carbon dioxide (pCO2) also influences the affinity of haemoglobin for oxygen

Question 12

How can the Bohr effect be seen on a dissociation curve ?

Answer 12

High carbon dioxide partial pressure causes a shift in the oxyhaemoglobin dissociation curve to the right

Question 13

How does a high pCO2 impact haemoglobin affinity for oxygen?

Answer 13

It decreases affinity for oxygen

Question 14

What happens to haemoglobin when the first oxygen molecule binds ?

Answer 14

It undergoes a conformational change that allows other oxygen molecules to bind more easily

Question 15

Where is the bicuspid valve found ?

Answer 15

Left atrioventricular valve

Question 16

Where is the tricuspid valve found ?

Answer 16

Right atrioventricular valve

Question 17

What are the 4 main vessels connecting to the heart ?

Answer 17

• Aorta
• Pulmonary vein
• Pulmonary artery
• Vena cava

Question 18

What is the job of the aorta and what is it connected to ?

Answer 18

It is connected to the left ventricle and carries oxygenated blood to all parts of the body except the lungs

Question 19

What is the job of the pulmonary vein and what is it connected to ?

Answer 19

It is connected to the left atrium and brings oxygenated blood back from the lungs

Question 20

What is the job of the pulmonary artery and what is it connected to ?

Answer 20

It is connected to the right ventricle and carries deoxygenated blood to the lungs where it is oxygenated and the carbon dioxide is removed

Question 21

What is the job of the Vena Cava and what is it connected to ?

Answer 21

It is connected to the right atrium and brings deoxygenated blood back from the tissues except the lungs

Question 22

What are the 3 stages of the cardiac cycle ?

Answer 22

• Atrial systole
• Ventricular systole
• Diastole

Question 23

Outline the process of atrial systole

Answer 23

Atria contract and this forces blood into the ventricles

Question 24

Outline the process of ventricular systole

Answer 24

Ventricles contract which forces the atrioventricular valves to shut and semi lunar valves to open. This forces blood to leave by the pulmonary artery and the aorta

Question 25

Outline the process of diastole

Answer 25

The atria and ventricles relax, elastic recoil of the heart lowers the pressure inside the heart chambers and blood returns to the heart from the vena cava and the pulmonary vein and fill the atria. Pressure increases in the atria until the atrioventricular valves open and blood flows into the ventricles. The relaxed atria and ventricles means that the semi-lunar valves are closed

Question 26

What is the structure and function of an artery ?

Answer 26

They are adapted to carry blood away from the heart to the rest of the body, thick walled to withstand high blood pressure, contain elastic tissue which allows them to stretch and recoil thus smoothing blood flow. They also contain smooth muscle which enables them to vary blood flow, lined with smooth endothelium to reduce friction and ease the flow of blood

Question 27

What is the structure and function of an arteriole ?

Answer 27

They branch off arteries, have thinner and less muscular walls, their role is to feed blood into capillaries

Question 28

What is the structure and function of an capillary ?

Answer 28

They are the smallest blood vessels, site of metabolic exchange, only one cell thick for fast exchange of substances

Question 29

What is the structure and function of a vein ?

Answer 29

They carry blood from the body to the heart, contain a wide lumen to maximise the volume of blood carried to the heart. They are thin walled as blood is under low pressure and contain valves to prevent the back-flow of blood. A weak pulse of blood means there is little elastic tissue or smooth muscle as there is no need for stretching and recoiling

Question 30

What is tissue fluid ?

Answer 30

It is a liquid containing dissolved oxygen and nutrients which serves as a means of supplying the tissues with the essential solutes in exchange for waste products such as carbon dioxide

Question 31

How is hydrostatic pressure created ?

Answer 31

It is created when blood is pumped along the arteries, into arterioles and then capillaries

Question 32

Outline the steps involved in the formation of tissue fluid

Answer 32

• Fluid is pushed out of the capillaries by build up of high hydrostatic pressure
• Substances in the tissue fluid diffuse into cells
• Water potential inside the capillaries decreases
• Water moves back into capillaries by tissue fluid
• Excess tissue fluid flows into the lymphatic system

Question 33

What are the components of tissue fluid ?

Answer 33

• Nutrients such as amino acids
• Fatty acids
• Ions in solution
• Glucose
• Oxygen

Question 34

What structure of the arteries swells to form an aneurysm?

Answer 34

The elastic fibres