Chapter 9 Adaptations For Transport (animals)

Question 1

What features of a transport system must all animals have?

Answer 1

A suitable medium
A pump
Valves

Question 2

What is an open circulatory system?

Answer 2

An open system involves the medium bathing tissues directly while held in a cavity rather than in blood vessels.

Question 3

What is the open circulation in insects?

Answer 3

They have a dorsal heart running the length of their body. It pumps the blood in open ended blood vessels into the haemocoel, where materials are exchanged between the blood and cells. Blood then returns to the heart and the circulation starts again.

Question 4

What is a closed circulatory system and what are the two types of closed system?

Answer 4

Blood moves in vessels. Single and double circulation.

Question 5

Describe the cardiac cycle

Answer 5

Atrial systole, the atrium walls contract and the blood pressure in the atria increases. This pushes the blood through the bicuspid/tricuspid valves down into the ventricles. Ventricular systole, the ventricle walls contract and increase the blood pressure in the ventricles. This forces blood up through the semi lunar valves out of the heart through the aorta and pulmonary artery. Diastole, both the atria and ventricles relax, this increases volume and decreases pressure causing the valves to shut preventing blood re-entering the heart.

Question 6

What is single circulation?

Answer 6

The blood moves through the heart once inits passage around the body.

Question 7

Describe the single circulation of earthworms

Answer 7

In earthworms, blood moves forward in the dorsal vessel and back in the ventral vessel. 5 pairs of pseudohearts pump the blood from the dorsal to the ventral vessel.

Question 8

Describe the single circulation of fish

Answer 8

In fish, the ventricle pumps deoxygenated blood to the gills. Oxygenated blood is carried to the tissues. From there, deoxygenated blood returns to the atrium of the heart and the circulation starts again.

Question 9

What is double circulation?

Answer 9

The blood passes through the heart twice in its passage around the body

Question 10

In mammals, what are the two types of systems within their double circulation?

Answer 10

Pulmonary and systemic

Question 11

What are the features of an artery?

Answer 11

Carries blood away from the heart. Thick muscular walls with a lot of elastic tissue. Not permeable. Blood flows rapidly under high pressure. Small lumen relative to diameter. Carries oxygenated blood except for pulmonary artery. Valves in aorta and pulmonary artery only.

Question 12

What are the features of veins?

Answer 12

Carries blood to the heart. Thin muscular walls with little elastic tissue. Blood flows slowly under low pressure. Large lumen relative to diameter. Carries deoxygenated blood except pulmonary vein. Valves in all veins.

Question 13

What are the features of capillaries?

Answer 13

Links veins and arteries. No muscle and no elastic tissue. Permeable. Blood flows under reducing pressure. Large lumen relative to diameter. Blood carried changes from oxygenated to deoxygenated. No valves.

Question 14

What is the function of endothelium in blood vessels?

Answer 14

One cell thick, smooth lining reducing friction to minimise resistance to blood flow.

Question 15

What is the function of the tunica media in blood vessels?

Answer 15

Contains elastic fibre and smooth muscle. Accommodates changes in blood flow and pressure. The elastic fibres recoil, pushing blood on through the vessel. This recoil is felt as a pulse and maintains blood pressure.

Question 16

What is the function of the tunica externa in blood vessels?

Answer 16

Contains collagen fibres to prevent overstretching.

Question 17

What is the contraction of cardiac muscle described as?

Answer 17

Myogenic - contracts without a nerve impulse or hormonal stimulation

Question 18

Describe the passage of blood in humans

Answer 18

Deoxygenated blood enters the vena cava. Enters the right atrium, passes through the bicuspid valve into the right ventricle. Leaves through the semi lunar valve out the pulmonary artery to the lungs. Oxygenated blood enters the pulmonary vein. Enters the left atrium, passes the tricuspid valve into the left ventricle. Leaves through the semi lunar valves out the aorta to the rest of the body.

Question 19

Describe how the heartbeat is controlled

Answer 19

Sino-atrial node (SAN) releases a wave of electrical stimulation, spreading over both atria causing them to contract (atrial systole). The ventricles are insulated, except at the atrio-ventricular node (AVN). This introduces a delay in transmission of the electrical impulse. The AVN spreads the wave down the bundle of His to the apex of the heart. The excitation is transmitted to purkinje fibres in the ventrcle walls carrying it upward through the muscles of the ventricle walls causing each ventricle to contract simultaneously from the apex upwards (ventricular systole).

Question 20

How do you calculate cardiac output?

Answer 20

Cardiac output = stroke volume x number of beats per minute

Question 21

What happens if the coronary arteries get blocked?

Answer 21

The muscles of the atria and ventricles cannot get enough oxygen to make ATP for contraction. In effect, pumping stops and muscle tissue dies leading to myocardial infarction (heart attack)

Question 22

What is an ECG?

Answer 22

Electrocardiograms trace the voltage changes produced by the heart.

Question 23

On an ECG what does the p wave show?

Answer 23

The voltage change generated by the sino-atrial node and the contraction of the atria

Question 24

On an ECG, What does the QRS wave show?

Answer 24

The depolarisation and contraction the ventricles

Question 25

On an ECG, what does the T wave show?

Answer 25

The repolarisation of the ventricle muscles

Question 26

On an ECG, what is the isoelectric line?

Answer 26

The line between the T wave and the P wave of the next cycle and acts as the baseline of the trace

Question 27

What are the components of blood?

Answer 27

55% plasma

45% cells such as erythrocytes, leucocytes, thrombocytes, blood proteins, etc…

Question 28

What is the structure and function of erythrocytes?

Answer 28

Biconcave disc shaped with no nucleus. Contains the respiratory pigment haemoglobin to transport oxygen.

Question 29

What is the function of leucocytes?

Answer 29

Monocytes and neutrophils engulf bacteria by phagocytosis

Lymphocytes produce antibodies

Question 30

How does haemoglobin transport oxygen?

Answer 30

Each haemoglobin has 4 haem groups, each containing an ion of iron. Haemoglobin has high affinity for oxygen at high partial pressures of oxygen, such as in the lungs. An oxygen molecule can bind to an ion of iron. Once an oxygen molecule has bonded, the shape of the haemoglobin changes making it easier for the next oxygen to attach. This is cooperative binding. At low partial pressures of oxygen, such as active tissue, haemoglobins affinity for oxygen decreases and the oxygen molecules dissociate.

Question 31

Why does myoglobin shift the dissociation curve to the left?

Answer 31

Oxymyoglobin dissociates its oxygen when the oxygen partial pressure is extremely low such as when exercising heavily. So myoglobin is described as an oxygen store. Since myoglobin has a higher affinity for oxygen than haemoglobin at the same partial pressures of oxygen, the dissociation curve shifts to the left.

Question 32

Why does foetal haemoglobin shift the dissociation curve to the left?

Answer 32

Foetal haemoglobin have a higher affinity for oxygen than adult haemoglobin at the same partial pressure. Foetal Blood flows very close to the placenta, so oxygen transfers to the foetus’s blood at any partial pressure of oxygen, the percentage saturation of the foetus’s blood is higher than an adults moving the dissociation curve to the left.

Question 33

What is the bohr effect?

Answer 33

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

Question 34

What are the 3 ways CO2 is transported?

Answer 34

In solution in plasma 5%
As hydrogen carbonate ion (HCO3-) 85%
Bound to haemoglobin as carbamino-haemoglobin 10%

Question 35

What is the chloride shift?

Answer 35

The diffusion of chloride ions from the blood plasma into the red blood cell, preserving electrochemical neutrality .

Question 36

What reactions occur in the red blood cell to haemoglobin to deliver oxygen and remove carbon dioxide?

Answer 36

Carbon dioxide diffuses into the red blood cell. Carbonic anhydrase catalyses the combination of CO2 and water making carbonic acid. Carbonic acid dissociates into H+ and HCO3- ions. The hydrogen carbonate ions diffuse out into the plasma. To balance the outflow of negative ions, chloride ions diffuse into the red blood cell. This is called the chloride shift. H+ ions cause oxygen and haemoglobin to dissociate. The H+ ions combine with the haemoglobin and oxygen diffuses out of the red blood cell into the tissues.

Question 37

What is tissue fluid?

Answer 37

Fluid from the blood plasma forced out of the capillaries and bathes the cells supplying them with solutes.

Question 38

What is the difference between tissue fluid and lymph?

Answer 38

Lymph is excess tissue fluid taken up into the lymphatic system.
Tissue fluid is the blood plasma forced out of the capillaries to bathe the cells.

Question 39

What happens at the arterial end of a capillary?

Answer 39

Blood is under high pressure from the pumping of the heart and contraction of the muscles in artery walls. The high hydrostatic pressure forces blood plasma out of the capillaries and bathes the cells, supplying them with solutes. The solutes such as glucose diffuse into the cells and waste products diffuse into the tissue fluid (plasma).

Question 40

What happens at the venous end of the capillaries?

Answer 40

The plasma proteins in the capillaries lower the bloods water potential. This high osmotic pressure pulls water inwards. Therefore, tissue fluid re-enters the capillaries by osmosis carrying the water products of cells. However, 10% of the tissue fluid is taken up by lymph capillaries into the lymphatic system.

Question 41

How does lymph re-enter the circulatory system?

Answer 41

Lymph eventually enters the thoracic duct, emptying the lymph into the subclavian vein above the heart.