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AS Biology > Transport in animals > Flashcards

Transport in animals Flashcards

1
Q

3.1.2 a)

Why don’t single-celled organisms need transport systems?

A

processes such as; diffusion, osmosis, active transport, endocytosis and exocytosis can supply everything the cell needs to import/export

BUT WHY??

  • Metabolic demand = Low
    • smaller organisms = less active
  • Smaller size = molecules, food, waste, etc. have short distances to travel
    • shorter diffusion pathway
  • SA:V ratio = High
    • more SA for capacity of the organism = supplies organisms demand
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2
Q

3.1.2 a)

What is the need of transport systems in multicellular animals?

A

important processes such as; diffusion, osmosis, active transport, endocytosis and exocytosis are not enough to supply the organism

BUT WHY??

  • Metabolic demand = High
    • lots of O2 + food required, lots of waste produced
  • Long distances for stuff to travel (size of animal)
    • increased diffusion pathway
  • SA:V ratio = Low
    • amount of SA to absorb/remove substances is too small for capacity of animal
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3
Q

List the different types of circulatory systems?

A
  • Open systems
  • Closed systems:
    • Single closed system
    • Double closed system
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4
Q

3.1.2 b)

Describe an open circulatory system

A
  • Very few (open ended) vessels
  • Hameolymph enters heart through pores called ostia then pumped towards head by peristalsis
  • Haemolymph comes into direct contact with tissues and cells (body cavity bathed in haemolymph) = this is where food and nitrogenous waste products are exchanged between haemolymph and tissues
  • Haemolymph pours straight into the haemocoel of the insect where it is then under low pressure
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5
Q

3.1.2 b)

What is insect blood called?

A
  • Haemolymph - transport medium
    • doesn’t carry O2 or CO2
      • ​gas exhchange takes place in the tracheal system
    • transports food, nitrogenous waste, and cells involved in defending against disease
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6
Q

3.1.2 b)

What is the body cavity of an insect called?

A
  • Haemocoel
    • body cavity - is split by a membrane
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7
Q

3.1.2 b)

What organisms are open-ended circulatory systems found in?

A
  • Mainly invertabrate animals
    • including most insects
    • some molluscs
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8
Q

3.1.2 b)

Where is the heart in an insect?

A
  • Heart (long muscular tube) extends along the length of thorax and abdomen, lies just under the dorsal (upper) surface of the body
    • Haemolymph travels through heart then dorsal aorta (open-ended vessel)
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9
Q

3.1.2 b)

What are the disadvantages of an open circulatory system?

A
  • Haemolymph circulates but steep diffusion gradients cannot be maintained for efficient diffusion
  • Amount of haemolymph flowing to a particular tissue cannot be varied to meet changing demands
  • Blood pressure = low
  • Blood flow = slow
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10
Q

3.1.2 b)

How is a closed circulatory system different to an open circulatory system?

A
  • Blood enclosed in blood vessels
  • Blood doesnt come into direct contact with other cells in the body
    • separate fluid (tissue fluid) bathes tissues + cells
  • Heart pumps blood around the body under higher pressure and relatively quickly
    • therefore faster delivery of O2 and nutrients
    • faster removal of CO2 and waste
  • Substances enter/leave blood by diffusion through walls of blood vessels
  • Amount of blood flowing to a particular tissue can be adjusted by widening/narrowing blood vessels
    • vasodilation/vasoconstriction
  • Most closed circulatory systems contain blood pigment (e.g. haemoglobin) that carries O2/CO2
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11
Q

3.1.2 b)

What organisms are closed circulatory systems found in?

A
  • Found in many different phyla
    • echinoderms
      • starfish, sea urchins etc.
    • cephalopod molluscs
      • octopods, squid etc.
    • annelid worms
      • common earthworm etc.
    • All vertebrate groups
      • including mammals
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12
Q

3.1.2 b)

What organisms are single closed circulatory systems found in?

A
  • Fish
  • Annelid worms (e.g. common earthworm)
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13
Q

3.1.2 b)

Describe the single closed circulatory system?

A
  • Blood travels once through the heart for each complete circulation of body
  • Blood passes through 2 sets of capillaries before returning to the heart
  • for fish:
    • first: capillaries in gills = exchanges O2 and CO2
    • second: capillaries in the rest of the body = substances exchanged between blood and cells
  • passing through 2 ses of capillaries = low blood pressure due to capillaries being narrow
    • results in blood getting back to heart quite slowly = limits efficiency of exchange processes => activity level of animal = Low
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14
Q

3.1.2 b)

Why are fish active even though they have a single closed circulatory system?

A
  • single closed circulatory system is sufficient for fish demand
  • countercurrent gaseous exchange mechanism in their gills = lots of intake of O2 from water
  • Reduced metabolic demands due to:
    • Body weight supported by water
    • Do not maintain their own body temp oC
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15
Q

3.1.2 b)

What organisms are a double closed circulatory system found in?

A
  • Active land animals
    • large + high metabolic demand
      • Birds
      • Most mammals
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16
Q

3.1.2 b)

What are the features of a good transport system?

A
  • medium - carry nutrients, O2 and waste around body
  • pump to create pressure - push fluid around body
  • exchange surfaces - allowing substances to enter/leave blood
  • tubes/vessels - carry fluid by mass flow
  • two circuits - one to pick up O2, one to deliver to tissues
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17
Q

3.1.2 b)

Describe a double closed circulatory system

A
  • Blood travels twice through the heart for each circuit of the body
  • Blood pumped from heart to lungs to pick up O2 and remove CO2 then back to heart (pulmonary circuit)
  • Blood pumped all around body then back to heart (systemic circuit)
  • each circuit only travels through one capiliary network
    • relative high blood pressure and fast blood flow can be maintained
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18
Q

3.1.2 e) i)

What is the heart?

A
  • organ (made up of cardiac muscle)
    • moves blood around the body
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19
Q

3.1.2 e) i)

What external structures/features does the heart have?

A
  • coronary artery
  • cardiac vein
  • inelastic pericardial membranes
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20
Q

3.1.2 e) i)

What are the four chambers of the heart?

A
  • consists of 4 chambers
  • left ventricle
    • pumps blood to the systemic circuit via aorta
  • right ventricle
    • pumps blood to the pulmonary circuilt via pulmonary artery
  • left atrium
    • filled with blood from systemic circuit via vena cava
  • right atrium
    • filled with blood from the pulmonary circuit via pulmonary vein
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21
Q

3.1.2 e) i)

What are the structures/features of the heart?

A
  • attached to each valve inside the heart are tendinous cords
    • these prevent valves from turning inside out during ventricular systole (ventricle contractions)
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22
Q

3.1.2 e) i)

What is the purpose of the inelastic pericardial membranes?

A
  • Help prevent the heart from over-distending with blood (AKA filling up too much)
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23
Q

3.1.2 e) i)

What are the issues associated with blockages in the coronary arteries?

A
  • Heart is a hardworking organ
    • vital for its muscle cells to get a constant supply of oxygenated blood and for its waste products to be removed
  • If coronary artery gets blocked
    • e.g. from a fatty diet, and a build up of low density lipids in the artery
  • Amount of O2 and nutrients delivered to the heart will be reduced
  • Patient may experience serious consequences
    • angina (severe heart pain)
    • heart attack (myocardial infarction)
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24
Q

3.1.2 e) i)

What is the purpose of the septum?

A
  • Seperates the left and right ventricle
    • ensures that oxygenated blood in the left ventricle and deoxygenated blood in the right ventricle do not mix
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25
Q

3.1.2 e) i)

Explain the variation in thicknesses of the chambers in the heart?

A
  • Left ventricle
    • wall of left ventricle usually 2 to 3 times thicker than right ventricle
    • needs to be thicker
      • because oxygenated blood in left ventricle is pumped through aorta (blood in arteries under higher pressure than veins)
      • and under a high pressure, because it has to travel a longer distance and needs to overcome the resistance of the systemic circulation
  • Right ventricle
    • wall of right ventricle is thicker than the walls of the atria
      • higher pressure than the atria, because ventricles pump blood through arteries, not recieving through veins
    • right ventricle pumps deoxygenated blood to lungs
    • and lungs are in the chest cavity close to the heart meaning not a long distance needs to be covered
    • therefore doesnt need to be as high a pressure as left ventricle, especially because alveoli are delicate and may be damaged by a high blood pressure
  • Atria
    • thinner muscle walls
    • do not need high pressure, because main purpose is to recieve blood from veins
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26
Q

3.1.2 f)

What does it mean to describe the heart as a myogenic muscle?

A
  • muscle that can initiate its own contractions
    • (pacemaker)
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27
Q

3.1.2 e) i)

Describe the structure of the cardiac muscle?

A
  • consists of fibres that branch
    • this produces cross bridges (see middle of micrograph)
    • help to spread stimulus around the heart, and ensure that muscle produces squeezing action rather than simple reduction in length
  • lots of mitochondria between muscle fibrils (myofibrils)
    • to supply energy for contractions
  • muscle cells seperated by intercalated discs (thick wavy blue line)
    • facilitate synchronised contraction
  • each cell has a nucleus and is divided into contractile units called sarcomeres (thin blue lines)
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28
Q

3.1.2 b)

How does an open circulatory system differ in larger and more active insects?

A
  • (e.g) locusts
  • Have open ended tubes attached to the heart
    • to direct blood towards more active parts of the body e.g. legs and wings
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29
Q

3.1.2 a)

What are the three main factors that influence the need of a transport system?

A
  • size
  • SA to V ratio
  • level of metabolic activity
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30
Q

3.1.2 a)

Why do waste products need to be removed?

A
  • If waste not removed
    • there will be a build up of waste
    • would become toxic
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31
Q

3.1.2 a)

Give specific examples of how size influences the need of a transport system?

A
  • long distance to travel = increased diffusion pathway
  • Molecules like hormones, enzymes = made in one place, needed in another
  • Food digested in one organ system, needs to be transported cells for respiration
  • Waste of metabolism needs to be transported from cells to excretory organs
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32
Q

3.1.2 b)

Why can’t the blood in the pulmonary circuit be as high as blood flowing through the systemic circuit?

A
  • if blood pressure is too high in pulmonary circuit, could damage delicate capiliaries in lungs
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33
Q

3.1.2 b)

advantages of double closed circulatory system?

A
34
Q

3.1.2) b)

What are the disadvantages of a single closed circuit in comparison to a double closed circuit?

A
  • blood pressure drops because blood passes through two sets of capiliares
  • blood has a low pressure as it flows towards body = will not flow as quickly
  • rate at which O2 + nutrients are delivered to respiring tissues and CO2 + urea removed, is limited.
35
Q

3.1.2 c)

What are arteries?

A
  • vessels that carry blood away from the heart
    • under higher pressure than veins
36
Q

3.1.2 c)

What are arterioles?

A
  • small vessels that distribute blood from an artery to the capillaries
37
Q

3.1.2 c)

What are capillaries?

A
  • very small vessels with very thin walls
38
Q

3.1.2 c)

What are venules?

A
  • small blood vessels that collect blood from capillaries and lead into veins
39
Q

3.1.2 c)

What are veins?

A
  • vessels that carry blood back to the heart
40
Q

3.1.2 c)

What are some examples of components utilised in some blood vessels?

A
  • Elastic fibres - composed of elastin and can stretch and recoil (elastic recoil), providing vessel walls with flexibility
  • smooth muscle - contracts or relaxes, changing the size of the lumen (channel within blood vessel)
  • collagen - provides structural support to maintain volume and shape of vessel (prevent it from collapsing)
  • endothelium - single layer of endothelial cells, is smooth, to reduce friction with flowing blood
41
Q

3.1.2 c)

Which artery carries oxygenated blood and which carries deoxygenated blood?

A
  • pulmonary artery carries deoxygenated to lungs
  • systemic arteries (e.g. aorta) oxygenated to rest of body
  • during pregnancy - umbilical artery, carries deoxygenated blood from fetus to placenta
42
Q

3.1.2 c)

Describe the structure and function of an artery

A
  • artery carries blood away from heart
  • lumen = relatively small –> to maintain high hydrostatic pressure
  • artery wall = thick –> withstand high hydrostatic pressure
  • artery wall = 3 layers
  • tunica interna/intima = thin layer of elastic tissue = allows wall to stretch and recoil (elastic recoil) within limits (maintained by collagen) –> maintain high hydrostatic pressure and take larger volume of blood
    • inner wall = folded to allow lumen to expand when blood flow = increased
  • tunica media = thick layer of smooth muscle = contracts/relaxes -> changes lumen size
  • tunica externa/adventita = thick layer of collagen and elastic tissue –> provides strength for high hydrostatic pressure and recoil = to maintain pressure
  • inside lined with endothelium (endothelial cells) reduces friction with flowing blood
43
Q

3.1.2 c)

Describe how it is possible to feel ones own pulse

A
  • pulse = surge of blood when heart contracts
  • elastic fibres reduce effects but cannot get rid of completely
  • reduced by elastic recoil which returns fibres to original length
  • to give continuous flow
44
Q

3.1.2 c)

Describe the structure and function of arterioles

A
  • arterioles = small blood vessels
    • distribute blood from artery to capillaries
  • more smooth muscle + less elastin in walls than arteries
  • layer of smooth muscle - can contract/dilate to vary lumen size
    • contraction of smooth muscle = vasoconstriction
    • smaller lumen = increased resistance + reduces rate of blood flow (preventing blood flowing into a capillary bed)
    • can be used to divert flow of blood to regions in need of more O2
    • relaxation = vasodilation, therefore blood flows into capillary bed
45
Q

3.1.2 c)

What is an aneurysm?

A
  • bulge or weakness in blood vessel
  • most common places: aorta and arteries in the brain
  • can be fatal
  • factors that can increase risk
    • high blood pressure
    • potentially if ratio of collagen to elastin is increased
46
Q

3.1.2 c)

Describe the structure and function of capillaries?

A
  • link arterioles to venules
  • very thin walls - allow for diffusion between blood and tissue fluid
  • walls consist of a single layer of flattened endothelial cells - reduces diffusion distance for exchanging materials
  • (for most areas of body) gaps between endothelial cells = relatively large
    • except CNS system (tight junctions between cells)
    • therefore walls = leaky, allowing blood plasma and dissolved substances to leave blood
  • narrow lumen = one red blood cell thick (cell has diameter of 7µm)
  • large SA for diffusion
  • total cross sectional area of capillary > than arteriole = rate of blood flow falls - (relatively slow movement) allowing time for exchange
47
Q

3.1.2 c)

Describe the structure and function of a venule?

A
  • collect blood from capillary bed - lead into veins
  • venule wall consists of
    • thin layers of smooth muscle
    • elastic tissue outside endothelium
    • thin outer layer of collagen
  • several venules join to form a vein
48
Q

3.1.2 c)

What are the two main vessels carrying deoxygenated blood back to the heart?

A
  • superior vena cava - from head + upper body
  • inferior vena cava - from lower parts of body
49
Q

3.1.2 c)

Why is the relative pressure in the veins very low?

A
  • do not have a pulse
    • surge from heart = lost after blood passes through narrow capillaries
  • however large reservoir of blood
    • 60% of blood in your veins at any one time
50
Q

3.1.2 c)

Describe the structure and function of a vein.

A
51
Q

3.1.2 d)

What is the main transport medium of human beings?

A
  • Blood - enclosed in vessels
    • contains a yellow liquid = plasma
    • contains cells (eg. red blood cells and white blood cells)
      • red blood cells = erythrocytes
      • white blood cells = leucocytes
    • contains platelets
52
Q

3.1.2 d)

What does plasma contain?

A
  • plasma makes up 55% of the blood by volume (most of that percentage = water)
  • O2 and CO2
  • dissolved glucose
  • amino acids
  • mineral ions
  • hormones
  • plasma proteins (e.g. albumin)
  • fibrinogen
  • globulins
53
Q

3.1.2 d)

What is albumin important for?

A
  • for maintaining the osmotic potential of blood
54
Q

3.1.2 d)

What is fibrinogen important for?

A
  • blood clotting
55
Q

3.1.2 d)

What are globulins involved in?

A
  • transport and immune system
56
Q

3.1.2 d)

What do red blood cells do?

A
  • carry O2 to the cells
  • give blood its red appearance
57
Q

3.1.2 d)

What are platelets?

A
  • fragments of large cells called megakaryocytes
    • cells found in the red bone marrow
  • involved in the clotting mechanism of the blood
58
Q

3.1.2 d)

What does the blood transport?

A

main functions of blood

  • maintain steady body temperature
  • acts as a buffer (minimising pH changes)
  • transport

But transport of what??

  • O2 to respiring cells
  • CO2 from respiring cells
  • digested food from small intestine
  • nitrogenous waste from cells to excretory organs
  • hormones (chemical messages/signals)
  • food molecules from storage compounds to cells that need them
  • platelets to damaged areas
  • cells and antibodies involved in the immune response
59
Q

3.1.2 d)

What is tissue fluid?

A
  • the fluid that fills spaces between cells and tissues (bathes cells + tissues)
  • comes into direct contact and supplies tissues with O2 and other nutrients
    • exchange of nutrients occurs across plasma membrane by diffusion, facilitated diffusion and active uptake (O2 enters, CO2 leaves cells)
  • formed by plasma leaking from the capillaries
  • CO2 and other waste products carried back into capillary
    • when some of the tissue fluid returns to capillary
60
Q

3.1.2 d)

What is oncotic pressure?

A
  • pressure created by the osmotic effects of the solutes
61
Q

3.1.2 d)

What is hydrostatic pressure?

A
  • pressure that fluid exerts when pushing against the sides of a vessel or container
62
Q

3.1.2 d)

How is the composition of tissue fluid different to that of blood?

A
  • blood plasma leaks through the capillaries
  • carries all the disolved substances
  • red blood cells, white blood cells, platelets and plasma proteins (particularly albumin) remain in blood
    • too big to pass through gaps in capillary wall
63
Q

3.1.2 d)

How does plasma leave the capillaries?

A
  • through gaps in the capillary wall
    • process called mass flow (not diffusion)
64
Q

3.1.2 e)ii)

What heart is commonly used in dissection?

A
  • sheep or pig
    • similar shape and size to a human heart
65
Q

3.1.2 e)ii)

What do you have to be aware of when drawing a heart?

A
  • hearts obtained from butcher = not always intact
    • major blood vessels cut off
    • atria often remove
    • because people don’t want to eat all the tubes
66
Q

3.1.2 e)ii)

What can be easily identified from the external view of a heart?

A
  • coronary arteries
    • supply the heart muscle with blood needed to beat
  • narrowing or blockage in coronary arteries causes symptoms of coronary heart disease or even heart attacks
67
Q

3.1.2 h)

What can be interpreted from the following ECG?

A
  • sinus rhythm
  • Normal ECG - no abnormalities
  • beats evenly spaced
  • rate between 60-100/min
68
Q

3.1.2 h)

What can be interpreted from the following ECG?

A
  • bradycardia
  • slow heart rate
  • beats evenly spaced
  • rate < 60/min
  • many people have bradycardia because of being fit
    • training makes heart beat more slowly + effectively
  • severe bardycardia can be serious
  • may need artificial pacemaker to keep heart beating steadily
69
Q

3.1.2 h)

What can be interpreted from the following ECG?

A
  • tachycardia
  • fast heart rate - very rapid
  • beats evenly spaced
  • rate > 100/min
  • often normal
    • e.g. after exercise, during fever, when frightened or angry
  • if abnormal may be caused by problems in the electrucal control of the heart and may need to be treated by medication or surgery
70
Q

3.1.2 h)

What can be interpreted from the following ECG?

A
  • ectopic heartbeat
  • altered rhythm
  • extra (early/ectopic) ventricular beat
  • followed by longer than normal gap before the next beat
  • most people have at least one a day
  • usually normal - but can be linked to serious conditions if very frequent
  • patient often feels as if a heartbeat has been missed
71
Q

3.1.2 h)

What can be interpreted from the following ECG?

A
  • Atrial fibrillation
  • irregular rhythm of atria - beating more frequently than ventricles - no clear P wave seen
  • ventricles lose regular rhythm
  • example of arrhythmia - means an abnormal rhythm of heart
    • rapid electrical impulses are generated in the atria
    • they contract very fast (fibrillate) up to 400 times a minute - but do not contract properly and only some of the impulses are passed on to the ventricles which contract much less often
    • as a result - heart does not pump blood effectively
72
Q

3.1.2 h)

What is an electrocardiogram?

A
  • a trace that records and monitors the electrical activity of the heart
  • doesn’t directly measure electrical activity of heart
  • instead number of electrode sensors painlessly attached to clean skin (to get good contact needed for reliable results)
  • measures tiny differences in skin
    • resulting from electrical activity generated by heart that spreads through tissues near heart and outwards to skin
  • sensors pick up electrical excitation created by heart and this signal is fed into a machine that converts it into a trace
73
Q

3.1.2 h)

Why is an ECG useful?

A
  • ECG - used to help diagnose heart problems
    • e.g. patient with heart attack
    • recognisable changes take place in the electrical activity of heart
  • diagnosis leads to problems being treated correctly and quickly
74
Q

3.1.2 h)

Describe the shape of the trace of a healthy persons electrocardiogram?

A
  • consists of a series of waves that are labelled P,Q,R,S,T
  • wave P shows the excitation of the atria
  • QRS indicates the excitation of the ventricles
  • T shows diastole
75
Q

3.1.2 i)

How are erythrocytes adapted to their main function?

A
  • erythrocytes (red blood cells) = very specialised
  • main function - transporting O2 from lungs to cells of the body
    • also involved in removal of CO2 from cells to the lungs for gaseous exchange
  • biconcave shape
    • has a larger surface area than simple disc or sphere structure, for diffusion of gases
    • also helps to pass through narrow capillaries
  • in an adult
    • erythrocytes continuously formed in red bone marrow
  • when mature erythrocytes enter circulation, they have lose their nuclei
    • maximises amount of haemoglobin that fits into the cells
    • also limits their life - last about 120 days in blood stream
76
Q

3.1.2 i)

What is haemoglobin?

A
  • the red pigment that carries O2 and gives erythrocytes their colour
  • a large complex globular conjugated protein with four subunits
  • each subunit consists of a polypeptide chain and a haem (non-protein) prosthetic group
    • each haem group contains a single iron ion (Fe2+)
    • iron ion can attract and hold O2 molecule
  • there are around 280 - 300 million haemoglobin molecules in each red blood cell
  • each haemoglobin molecule can bind to 4 O2 molecules
    • because each haem group can associate with one O2 molecule
77
Q

3.1.2 i)

What does affinity mean?

A
  • a strong attraction
  • the haem groups in haemoglobin are said to have a high affinity for O2
78
Q

3.1.2 i)

What happens to haemoglobin when it associates with O2?

A
  • O2 binds quite loosely to haemoglobin
    • forming oxyhaemoglobin
  • the reaction is reversible

Hb + 4O2 ⇌ Hb(O2)4

Hb = haemoglobin

O2 = oxygen

Hb(O2)4 = oxyhaemoglobin

79
Q
A
80
Q

3.1.2 j)

How is fetal haemoglobin different to adult haemoglobin?

A
  • fetal haemoglobin has a higher affinity for O2 than adult haemoglobin
  • at every point along the dissociation curve, fetal haemoglobin is to the left

AS Biology (8 decks)

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