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Biology > MODULE 3: EXCHANGE AND TRANSPORT - TRANSPORT IN ANIMALS > Flashcards

MODULE 3: EXCHANGE AND TRANSPORT - TRANSPORT IN ANIMALS Flashcards

1
Q

Give reasons why multicellular organisms usually need a transport system, but unicellular organisms don’t

A
  • Multicellular organisms are relatively big, having a lower SA:V ratio (unicellular organisms are usually smaller with a higher SA:V ratio)
  • A lot of multicellular organisms (e.g. mammals) are very active - large no. of cells respiring very quickly so they need a constant, rapid supply of glucose + oxygen
    -Multicellular organisms have a higher metabolic rate
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2
Q

What is the metabolic rate?

A

The speed at which chemical reactions take place in the body

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3
Q

Describe why a fish’s circulatory system is described as a single circulatory system.

A

The heart pumps blood to the gills (to pick up oxygen) and then on through the rest of the body (to deliver oxygen) in a single circuit

BLOOD ONLY PASSES THROUGH THE HEART ONCE FOR EACH COMPLETE CIRCUIT OF THE BODY

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4
Q

Describe why the mammalian circulatory system is described as a double circulatory system.

A
  • The heart is divided down the middle in mammals
  • The right side of the heart pumps blood to the lungs (to pick up oxygen)
  • From the lungs, blood travels to the left side of the heart, which pumps it to the rest of the body
  • When blood returns to the heart, it enters the right side again

THE BLOOD PASSES THROUGH THE HEART TWICE IN A COMPLETE CIRCUIT OF THE BODY

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5
Q

What are the names of the two systems that our mammalian circulatory system is made up of

A
  • Pulmonary system
  • Systematic system
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6
Q

Give one advantage of the mammalian double circulatory system

A

The heart can give the blood an extra push between the lungs and the rest of the body, making the blood travel faster, so oxygen is delivered to the tissues more quickly

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7
Q

What is a closed circulatory system?

A

The blood is enclosed inside blood vessels

All vertebrates (e.g. fish and mammals) have a closed circulatory system

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8
Q

What is an open circulatory system?

A

Blood isn’t enclosed in blood vessels all the time. It instead flows freely through the body cavity

Some invertebrates (e.g. insects) have an open circulatory system

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9
Q

Describe the structures of a closed circulatory system

A
  • The heart pumps blood into arteries, these branch out into millions of capillaries
  • Some substances like oxygen and glucose diffuse from the blood in the capillaries into the body cells, but the blood stays inside the blood vessels as it circulates
  • Veins take the blood back to the heart
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10
Q

Describe the structures of an open circulatory system

A
  • The heart is segmented | It contracts in a a wave, starting from the back, pumping the blood into a single main artery
  • That artery opens up into the body cavity
  • The blood flows around the insect’s organs, gradually making its way back into the heart segments through a series of valves

In insects, the blood doesn’t supply the insect’s cells with oxygen - this is done by the tracheal system

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11
Q

Name the five types of blood vessel

A
  • Arteries
  • Arterioles
  • Capillaries
  • Venules
  • Veins
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12
Q

Explain the structure of arteries and their role

A
  • Carry blood from the heart to the rest of the body
  • Thick, muscular walls + elastic tissue to stretch and recoil as the heart beats (helps maintain high pressure)
  • Endothelium (inner lining) of folded, allowing artery to expand (and helps maintain high pressure)
  • All arteries carry oxygenated blood except for pulmonary arteries, which take deoxygenated blood to the lungs
  • Narrow lumen
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13
Q

Explain the structure of arterioles and their role

A
  • Arteries branch into arterioles (smaller than arteries)
  • Layer of smooth muscle - less elastic tissue
  • Smooth muscle allows to expand or contract, controlling amount of blood flow to tissues
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14
Q

Explain the structure of capillaries and their role

A
  • Smallest of the blood vessels (one cell thick)
  • Substances like glucose + oxygen are exchanged between cells + capillaries, so adapted for efficient diffusion
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15
Q

Explain the structure of venules and their role

A
  • Very thin walls that contain some muscle cells
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16
Q

Explain the structure of veins and their role

A
  • Venules join together to form veins
  • Take blood back to the heart under low pressure
  • Wider lumen than equivalent arteries, with very little elastic or muscle tissue
  • Contain valves to stop blood flowing backwards
  • Blood flow through the veins is helped by contraction of the body muscles surrounding them
  • All veins carry deoxygenated blood except for the pulmonary veins (carry oxygenated blood to the heart from the lungs)
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17
Q

What is tissue fluid?

A

The fluid that surrounds cells

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18
Q

What is a capillary bed?

A

The network of capillaries in an area of tissues

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19
Q

Describe the process of pressure filtration

A
  • At the start of the capillary bed, nearest the arteries, the hydrostatic pressure inside the capillaries is greater than the hydrostatic pressure in the tissue fluid | This difference in hydrostatic pressure forces fluid out of the capillaries and into the spaces around the cells, forming tissue fluid
  • As fluid leaves, the hydrostatic pressure reduces in the capillaries - so the hydrostatic pressure is much lower at the end of the capillary bed that’s nearest to the venules
  • There is another form of pressure at work here called oncotic pressure - this is generated by plasma proteins present in the capillaries which lower the water potential | At the venule end of the capillary bed, the water potential in the capillaries is lower than the water potential in the tissue fluid due to the fluid loss from the capillaries and the high oncotic pressure | This means some water re-enters the capillaries from the tissue fluid at the venule end by osmosis
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20
Q

What happens to excess tissue fluid left over from pressure filtration?

A
  • The smallest lymph vessels are the lymph capillaries
  • Excess tissue fluid passes into lymph vessels | once inside, it’s called lymph
  • Valves in the lymph vessels stop the lymph going backwards
  • Lymph gradually moves towards the main lymph vessels in the thorax (chest cavity) | Here, its; returned to the blood, near the heart
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21
Q

List the components of blood

A
  • Red blood cells
  • White blood cells
  • Platelets
  • Proteins
  • Water
  • Dissolved solutes
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22
Q

List the components of tissue fluid

A
  • Very few white blood cells
  • Very few proteins
  • Water
  • Dissolved solutes
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23
Q

List the components of lymph

A
  • White blood cells
  • Only antibodies (proteins)
  • Water
  • Dissolved solutes
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24
Q

Describe the placement of red blood cells

A

Red blood cells are too big to get through capillary walls into tissue fluid

  • Blood
25
Q

Describe the placement of white blood cells

A

Most white blood cells are in the lymph system. They only enter tissue fluid when there’s an infection

  • Blood
  • Tissue fluid (very few)
  • Lymph
26
Q

Describe the placement of platelets

A

Only present in tissue fluid if the capillaries are damaged

  • Blood
27
Q

Describe the placement of proteins

A

Most plasma proteins are too big to get through capillary walls

  • Blood
  • Tissue fluid (very few)
  • Lymph (only antibodies)
28
Q

Describe the placement of water

A

Tissue fluid and lymph have a higher water potential than blood

  • Blood
  • Tissue fluid
  • Lymph
29
Q

Describe the placement of dissolved solutes

A

Solutes (e.g. salt) can move freely between blood, tissue fluid and lymph

  • Blood
  • Tissue fluid
  • Lymph
30
Q

What are the two types of valve in the heart?

A
  • Atrioventricular valves
  • Semi-lunar valves
31
Q

Explain how valves work

A
  • Atrioventricular valves link the atria to the ventricles
  • Semi-lunar valves link the ventricles to the pulmonary artery and aorta
  • Valves open only one way - whether they’re open or closed depends on the relative pressure of the heart chambers
  • If there’s higher pressure behind a valve, it’s forced open
  • If pressure is higher in front of the valve, it’s forced shut
32
Q

What is the cardiac cycle?

A

An ongoing sequence of contraction and relaxation of the atria and ventricles that keeps blood continuously circulating around the body

33
Q

Explain atrial systole

A
  • Ventricles are relaxed
  • Atria contract, which decreases their volume + increases pressure
  • This pressure pushes the blood into the ventricles through the atrioventricular valves
  • There’s a slight increase in ventricular pressure + volume as the ventricles receive the ejected blood from the contracting atria
34
Q

Explain ventricular systole

A
  • Atria relax
  • Ventricles contract (decreasing their volume), increasing their pressure
  • Pressure becomes higher in the ventricles than the atria, which forces the atrioventricular valves shut to prevent back-flow
  • The high pressure in the ventricles opens the semi-lunar valves - blood is forced out into the pulmonary artery and aorta
35
Q

Explain diastole

A
  • Ventricles and atria both relax
  • The higher pressure in the pulmonary artery and aorta causes the semi-lunar valves to close, preventing back-flow
  • The atria fill with blood (increasing their pressure) due to the higher pressure in the vena cava and pulmonary vein
  • As the ventricles continue to relax, their pressure falls below the pressure in the atria
  • This causes the atrioventricular valves to open and blood flows passively (without being pushed by atrial contraction) into the ventricles from the atria
  • The atria contract and the whole process begins again
36
Q

What is cardiac output?

A

The volume of blood pumped by the heart per minute

37
Q

How is cardiac output calculated?

A

Cardiac output = heart rate x stroke volume

38
Q

Which chamber of the heart receives blood from the lungs?

A

Left atrium

39
Q

Which chamber of the heart receives blood from the body?

A

Right atrium

40
Q

Define myogenic

A

This means the heart can contract and relax without receiving signals from nerves

41
Q

What is the process of a heartbeat?

A
  • Starts in the sino-atrial node (SAN), which is in the wall of the right atrium
  • The SAN is like a pacemaker, setting the rhythm of the heartbeat by sending out regular waves of electrical activity to the atrial walls
  • This causes the right and left atria to contract at the same time
  • A band of non-conducting collagen tissue prevents the waves of electrical activity from being passes directly from the atria to the ventricles
  • instead, those waves of electrical activity are transferred from the SAN to the atrioventricular node (AVN)
  • The AVN is responsible for passing the waves of electrical activity on to the bundle of His - but there’s a slight delay before the AVN reacts, to make sure the ventricles contract after the atria have emptied
  • The bundle of His is a group of muscle fibre as responsible for conducting the waves of electrical activity to the finer muscle fibres in the right and left ventricle walls, called the Purkyne tissue
  • The Purkyne tissue carries the waves of electrical activity into the muscular walls of the right and left ventricles, causing them to contract simultaneously, from the bottom up
42
Q

What is an electrocardiogram?

A

A machine that records the electrical activity of the heart
The heart muscle depolarises (loses electrical charge) when it contracts, and repolarises (regains charge) when it relaxes

43
Q

What is the P wave in an ECG trace?

A

Caused by contraction (depolarisation) of the atria

44
Q

What is the QRS complex in an ECG trac and what causes it?

A

The main peak of the heartbeat, together with the dips at either side
Caused by contraction (depolarisation) of the ventricles

45
Q

What is the T wave in an ECG trace?

A

Due to the relaxation (repolarisation) of the ventricles

46
Q

What is the height of a wave in an ECG trace?

A

This indicates how much electrical charge is passing through the heart - a bigger wave means more electrical charge, so (for the P and R waves) a bigger wave means a stronger contraction

47
Q

What is tachycardia?

A
  • The heartbeat is too fast - around 120 beats per minute
  • Fine during exercise, but at rest is shows that the heart isn’t pumping blood efficiently
48
Q

What is bradycardia?

A
  • A heartbeat is too flow - below 60 beats per minute at rest
49
Q

What is an ectopic heartbeat?

A
  • An ‘extra’ heartbeat
  • May be caused by an earlier contraction of the atria than in the previous heartbeats
  • Can be caused by early contraction of the ventricles, too

Ocean sail ectopic heartbeats in. A healthy person don’t cause a problem

50
Q

What is fibrillation?

A
  • A really irregular heartbeat
  • The atria or ventricles completely lose their rhythm and stop contracting properly
  • Can result in anything from chest pain + fainting to lack of pulse + death
51
Q

Explain the structure of haemoglobin

A
  • Red blood cells contain haemoglobin (Hb)
  • Haemoglobin is a large proteins with a quaternary structure - made up of more than one polypeptide chain (four)
  • Each chains has a haemoglobin group which contains irons and give haemoglobin its red colour
  • Haemoglobin has a high affinity for oxygen - each molecule can carry four oxygen molecules
  • In the lungs, oxygen joins to the iron in Haemoglobin to form oxyhaemoglobin (reversible - oxygen dissociated from it near the body cells in exchange for carbon dioxide)
52
Q

What is the partial pressure of oxygen?

A

A measure of oxygen concentration
The greater the concentration of dissolved oxygen in cells, the higher the partial pressure
(pO₂)

same with partial pressure of carbon dioxide (pCO₂)

53
Q

Explain how haemogblin’s affinity for oxygen varies depending on partial pressure of oxygen

A
  • Oxygen loads onto haemoglobin to form oxyhaemoglobin where there’s high pO₂ (alveoli in lungs)
  • Oxyhaemoglobin unloads its oxygen where there’s a lower pO₂ (where cells respire, using up oxygen)
  • Haemoglobin returns to the lungs to pick up more oxygen
54
Q

How is fetal haemoglobin different to adult haemoglobin?

A
  • Fetal haemoglobin has a higher affinity for oxygen (the fetus’ blood is better at absorbing oxygen that its mother’s blood) at the same partial pressure of oxygen
  • The fetus gets oxygen from its mother’s blood across the placenta
  • By the time the mother’s blood reaches the placenta, its oxygen saturation has decreased (because some has been used up by the mother’s blood)
  • For the fetus to get enough oxygen to survive, it’s haemoglobin has to have a higher affinity for oxygen (so it takes up enough)
  • If its haemoglobin had the same affinity for oxygen as adult haemoglobin its blood wouldn’t be saturated enough
55
Q

How does carbon dioxide concentration affect oxygen unloading?

A
  • Haemoglobin gives up its oxygen more readily at higher partial pressure of carbon dioxide (pCO₂) to get more oxygen to cells during activity - when cells respire they produce carbon dioxide, which raises the pCO₂, increasing the rate of oxygen unloading
  • Most of the CO₂ from respiring tissues diffuses into red blood cells - here it reacts with water to form carbonic acid, catalysed by carbonic anhydrase (the rest of the CO₂, around 10%, binds directly to haemoglobin and is carried to the lungs)
  • The carbonic acid dissociates (splits up) to give hydrogen ions and hydrogencarbonate ions
  • The increase in H ions causes oxyhaemoglobin to unload its oxygen so that haemoglobin can take up the H ions - this forms the compound haemoglobinic acid (this process stops H ions from increasing cell’s acidity)
  • Hydrogencarbonate ions diffuse out of the red blood cells and are transported into the blood plasma | To compensate for loss of hydrogencarbonate ions from the red blood cells, chloride ions diffuse into the red blood cells (chloride shift - maintains balance of charge between red blood cell and plasma)
  • When the blood reaches the lungs the low pCO₂, causes some of the hydrogencarbonate and hydrogen ions to recombine into CO₂ (and water)
  • The CO₂ then diffuses into the alveoli and is breathed out
56
Q

What is the Bohr effect?

A

When carbon dioxide levels increase, the dissociation curve shifts right, showing that more oxygen is released from the blood (because the lower the saturation of haemoglobin with oxygen, the more oxygen is released

57
Q

What is hydrostatic pressure?

A

The pressure created by water in an enclosed system

58
Q

What is oncotic pressure?

A

The tendency of water to move into the blood by osmosis as a result of the plasma proteins

Biology (26 decks)

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