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OCR Biology A Level > 3.1.2 Transport In Animals > Flashcards

3.1.2 Transport In Animals Flashcards

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1
Q

Why are mass transport systems needed in multicellular organisms?

A
  • As size increases, distance betweencels + to outside of bodt is too far for diffusion to meet demands of organism
  • As size increases, SA:VOL ratio decreases - amount pf surface area realtivley shrinks
  • As size increases, metabolic demands + waste products increase - these need removing
  • Hormones + food may need to be trasnsported to other organs + cells within the organism
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2
Q

List components of an efficient circulatory system, and examples in humans

A
  • A pump (heart)
  • A means of maintaining pressure (muscle + elastic tissue in aorta + arterioles)
  • A transport meidum (blood/plasma)
  • An exchange surfce (Capillary bed)
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3
Q

What is the difference between a closed and open circulatory system?

A

Open: Blood not always maintained inside vesselsa - can circulate in body cavity + bathe body organs directly
Closed: Blood always maintained inside vessels

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4
Q

List key aspects of an open circulatory system

A
  • primitive system found in invertebrates
  • blood not contained in blood vessels
  • heart pumps transport medium(haemolymph) into vessels that empty into large cavities containing organs
  • open body called ‘haemocoel’
  • haemolymph comes into direct contact with tissue
  • haemolymph diffuses through tissue into heart
  • haemolymph doesn’t carry oxygen + CO2
  • low pressure
  • steep diffusion gradients not maintained
  • amount of flow cannot be varied
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5
Q

List key aspects of a closed circulatory system

A
  • found in higher animals
  • blood maintained inside vessels
  • blood doesn’t come into direct contact with body cells
  • blood carries oxygen + CO2
  • higher pressure
  • amount of flow can be varied/directed
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6
Q

Explain the difference between a single and double circulatory system and give exampels of where each is found

A

Single: Blood passes through heart once for each circulation of body e.g. fish
Double: Blood passes through heart twice for each circulation of body e.g. mammals

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7
Q

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

A
  • countercurrent gaseous exchange mechanism at gills
  • bodyweight supported by water
  • don’t maintain own body temperature
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8
Q

What is the advantages of a double circulatory system?

A

The heart can increase pressure of blood flow after passing through lungs - blood flow more rapid to tissues

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9
Q

Explain the structure of arteries, arterioles amd veins from the outside in

A
  1. Collagen fibres (tunica externa)
  2. Smooth muscle layer
  3. Elastic layer
  4. Endothelium
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10
Q

Give key aspects of arteries

A
  • carry blood away from heart
  • lumen smaller than veins but bigger than capillaries
  • blood under higher pressure than veins
  • rapid blood flow
  • blood flow in pulses
  • no valves
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11
Q

What allows arteries to withstand and maintain high pressure?

A
  • thick tunica externa with collagen
  • thick smooth muscle layer to allow lumen diameter to change
  • thick elastic fibre layer that stretches + recoils to maintain pressure
  • endothelium folded to prevent damage - can stretch and smooth so blood flows easily over it
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12
Q

Give key aspects of arterioles

A
  • link arteries + capillaries
  • more smoth muscle than arteries - to constrict or dilate to control blood flow to specific organ
  • vasoconstriction: smooth muscle contracts to constrict vessel so blood flow decreaes
  • vasodilation: smooth muscle relaxes so blood flow increases
  • less elastin in walls
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13
Q

Give key aspects of veins

A
  • carry blood back to heart
  • thin muscular walls
  • little elastic tissue
  • relativley large lumen
  • low blood pressure + flow
  • no pulse
  • valves (prevent backflow)
  • 60% of blood volume in veins
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14
Q

Explain a challenge experienced when returning blood to the heart and 3 adaptations the body has to overcome this problem

A

Challenge
- blood in veins is deoxygenated - must be returned to heart then lungs to pick up oxygen
- however, blood under low pressure + has to move against gravity

Adaptations
- one way valves to prevent backflow
- bigger veins run through big active muscles - when these contract, veins are squeezed, forcing blood towards the heart
- breathing movements of chest act as pump - presure changes + squeezing actions move blood in veins of chest + abdomen

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15
Q

How do valves work in veins?

A
  • blood has higher pressure so valve opens as heart contracts
  • heart in diastole pressure is greatre on opposite side so valve closes
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16
Q

Give key aspects of capillaries

A
  • links up arterioles + venules in tissues
  • no layers
  • wall one cell thick (squamous endothelium)
  • small aps between cells for passage of phagocytes + materials
  • small lumen (just large enough for red blood cells in single file
  • low pressure + flow
  • no valves
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17
Q

List adaptations of capillaries that allow for efficient exchange of materials

A
  • large surface area for diffusion in + out of blood
  • total cross setional area of capillaries is greater thgan arteriole - rate of blood flow decreases for more time for exchange of materials by diffusion
  • pressue lower than arteries, so walls aren’t damaged
  • one cell thick wall gives short diffusion path
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18
Q

List functions of blood

A
  • oxygen for aerobic respiration
  • CO2 from respiring cells
  • waste products from cells to excretory organs
  • chemical messengers (e.g. hormones)
  • food molecules (e.g. glucose)
  • platelets to damaged areas
  • cells + antibodies involved in immune response
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19
Q

Why is pressure of the blood at arterial end of blood capillary so high?

A
  • the contraction of ventricular muscle of the heart (creates high hydrostatic pressure)
  • this forces fluid out of tiny gaps between endothelium cells in the capillary
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20
Q

What is tissue fluid and why is it needed?

A
  • Plasma with dissolbed nutrients (glucose, amino acids, fatty acids) + oxygen
  • Red blood cells can’t leave the capillaries, however the high hydrostratic pressure forces the fluid out of tiny gaps in the capillary walls, which then bathes the surrounding cells
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21
Q

What can and can’t leave the blood?

A

Can: Plasma, dissolved nutrients, oxygen, neutrophil + lymphocytes
Can’t: Red blood cells, most white blood cells, platelets, plasma proteins

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22
Q

What is hydrostatic, oncotic and filtratrion pressure?

A

Hydrostatic: Pressure created by water in an enclosed system
Oncotic: The tendency of water to move into the blood by osmosis as a result of the plasma proteins that remain in the blood
Filtration: Size of hydrostatoc pressure - size of oncotic pressure

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23
Q

Using the terms hydrostatic pressure, oncotic pressure, arterial end and venous end, explain how tissue fluid leaves and returns to capillaries

A
  • at arterial end of capillary, hydrostatric pressue is greater size than oncotic pressure
  • net outflow of fluid out of capillary - fluid pushed out of capillary - tissue fluid is formed
  • at venous end of capillary, oncotic pressure is still the same, however hydrostatric pressue is smaller size than oncotic pressure
  • net inflow of fluid into the capillary - fluid moves into capillary with dissolved waste (e.g. C02)
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24
Q

What hapens to waste products after tissue fluid has been transferred?

A
  • urea + carbon dioxide leave cells and enter tissue fluid - enters blood stream at venous end of capillary
  • exccess tissue fluid drains into lymphatic system
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25
Q

What is the lymphatic system?

A
  • a network of vessels throughout the body
  • contents are drained into bloodstream via 2 ducts that join a vein close to the heart
  • lymph is moved by hydrostatic pressure + contraction of body muscles
  • also absorb fatty acids + triglyceride hydrolysis that take place udring digestion in small intestine
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26
Q

What is elephantiasis

A
  • reduces the lymphatic system’s ability to take up fluids that leak from capillaries
  • caused by parasitic worm
  • causes swelling
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27
Q

How does lymph differ to the tissue fluid that leaves the blood at the arterial end of a blood capillary?

A
  • less oxygen (used in aerobic respiration)
  • less nutrients (used in body cells for aerobic respiration)
  • more carbon dioxide (made in aerobic respiration)
  • more urea (made by body cells)
  • more fatty material (absorbed from intestines)
  • many more lymphocytes made in lymph nodes
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28
Q

What systems does the heart pump?

A

Pulmonary (to the lungs) + Systematic (to the rest of the body)

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29
Q

What does the term myogenic mean in relation to the heart?

A

The hear beats from within the muscle itself

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30
Q

Name the chambers of the heart

A
  • left atrium
  • left ventricle
  • right atrium
  • right ventricle
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31
Q

Name the blood vessels that enter and/or exit the heart

A
  • pulmonary artery
  • vena cava
  • aorta
  • pulmonary vein
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32
Q

Name the valves found in the heart

A
  • left AV valve
  • right AV valve
  • semi-lunar valves
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33
Q

What is the tissue seperating the two sides of the heart, and what is the bottom point of the heart called?

A
  • septum
  • apex
34
Q

Which chambers are thicker and thinner in the heart?

A
  • arterial walls are thinner than ventricle walls
  • left ventricle has thicker muscle walls than right venticle
35
Q

What are important talking points to mention when discussing the heart?

A
  • distance
  • resistance
  • thickness of chamber wall/muscle
  • force
  • pressure (force/area = pressure)
36
Q

What do coronary arteries do?

A

Supply oxygenated blood to cardiac muscle

37
Q

Why are there more coronary arteries on the left ventricle?

A

To provide more force, to create higher pressure - blood pushing against greater friction
- left ventricle pushes blood further around the body

38
Q

Why must the heart have a constant blood supply?

A
  • it is an organ and requires ATP
  • must have a constant oxygen supply to respire
39
Q

What is the purpose of heart valves?

A
  • to ensure blood only flows in one direction through the heart
  • valves will only open one direction due to tendinous cords
  • open and close due to pressure differences on each side
40
Q

What are the purposes of AV and semi-lunar valves?

A

AV valves: Stop back-flow into atria when wall muscle contracts
Semi-lunar valves: Stop back-flow into ventricles when ventricle wall muscle relaxes

41
Q

What is systole and diastole?

A

Systole: Period of contraction of cardiac muscle
Diastole: Period of relaxation of the cardiac muscle

42
Q

Give key aspects of heart muscle

A
  • also known as cardiac muscle
  • myogenic (initiate its own contraction)
  • contraction of muscles of atria and ventricle are synchronised to prevent fibrillation
  • muscle of atria contract before muscle of ventricle
43
Q

What are heart sounds described as and where do they come from?

A

‘lub-dub’
- 1st sound comes when atrioventricular valves close as the ventricle muscle contracts
- 2nd sound comes as the semi-lunar valve closes, as the ventricle muscle relaxes

44
Q

What is heart rate and how is it measured?

A
  • how many times a person’s heart beats in a minute
  • measured in bpm
  • wave of excitation initiated approx. 55-80 times a minute - making heart beat
  • resting heart rate depends on factors age, stress, diet, fitness etc
45
Q

How is heart rate calculated?

A

60 / length of cardiac cycle = beats per min-1

46
Q

What is stroke volume and cardiac output?

A

Stroke volume: The volume of blood pumped out by the left ventricle each time the heart beats
Cardiac output: The volume of blood pumped out by the left ventricle in on minute

47
Q

How is cardiac output (dm3 min-1) calculated?

A

Heart rate (beats min-1) x stroke volume (dm3 beat-1)

48
Q

What parts of the heart play a role in initiation and coordination of heart action?

A
  • SAN (sinoatrial node)
  • AVN (atrioventricular node)
  • Bundle of His
  • Bundle branches (containing purkyne fibres)
  • Disc of non-conducting fibres
49
Q

Give key aspects of the SAN

A
  • sinoatrial node
  • also known as pacemaker
  • top of right atrium
  • near the point where vena cava empties blood into atrium
  • initiates a wave of excitation at regular intervals
50
Q

Give key aspects of the AVN

A
  • atrioventricular node
  • top of inter-ventricular septum
  • the only route through the disc of non-conducting tissue
51
Q

How is the wave of excitation stopped?

A
  • base of atria is disc if tissue that can’t conduct the wave of excitation
  • this means wave of excitation cannot spread directly to ventricle walls
52
Q

Explain how heart action is initiated and coordinated

A
  1. SAN initiates wave of electrical excitation
  2. Wave spreads over walls of atria causing cardiac muscle to contract (atrial systole)
  3. Wave stopped by disc of non-conducting fibres - stops wave from passing directly into walls of ventricle - can only pass via AVN
  4. Impulse reaches AVN - is delayed through node to allow complete contraction of muscle of atria, for blood to flow into ventricles before ventrical start to contract
  5. Wave travels down purkyne fibres in bundle of His, in the inter-ventricular septum
  6. One impulse reaches base of ventricle, it spreads over walls of ventricles + causes muscle of ventricle to contract from apex upwards - ventricular systole
  7. Blood pushed up to major arteries at top of heart
  8. Heart muscle relaxes (diastole)
53
Q

What are the two types of muscle called?

A

Skeletal muscle (voluntary)
Smooth muscle (involuntary)

54
Q

What walls are thickest in the heart and why?

A

Atrial walls thicker than ventricle walls
Left ventricle wall thicker than right ventricle - provides more force to create higher pressure as greater friction when pushing blood around the entire body

55
Q

Tieps of reading heart pressure graph

A
  • blood flows from area of high to low pressure
  • when muscle of heart chamber contracts, pressure increases of cahmber
  • when lines cross, something has happened to valve (opened or closed)
  • if two lines diverge from each other, valve has shut
  • if two lines are parallel, a valve is open
56
Q

What are electrocardiograms and what are the used for?

A

Used to monitor the electrical activity of the heart
Electrical activity generated by heart, picked up by sensors on skin converted to a trace

57
Q

At which stages does the heart gain and lose charge?

A

Depolarises (loses electrical charge) when contracting
Repolarises (regains electrical charge) when relaxing

58
Q

Give key aspects of electrocardiograms

A
  • electrical activity on y-axis
  • time in seconds on x-axis
  • P wave: excitation of atria
  • Q,R,S complex: excitation of venttreicles
  • T wave: diastole
59
Q

What is Tachycardia?

A
  • when heart rate is over 100bpm
  • normal during excersise, when scared or fever
  • if abnormal, may be caused by problems with electrical control of heart (may need medication or surgery)
60
Q

What is Bradycardia?

A
  • when heart rate slows down (below 60bpm)
  • can be due to high fitness level (training allows hear to beat slower + more efficiently)
  • severe bradycardia can be serious + require a pacemaker
61
Q

What is an ectopic heart beat?

A
  • extra heartbeat out of normal rhythm
  • most people have ~1 a day
  • when expereinced frequently can lead to a serious condition
62
Q

What is arrhythmia?

A
  • abnormal rhythm of the heart
  • rapid electrical impulses generated in atria (up to 400 a minute)
  • atria doesn’t contract properly
  • only some impulses pass onto the ventricles, so contract less often
63
Q

What is myocardial infraction and ventricular hypertrophy?

A

Myocardial infraction: blood clot in coronary artery starves heart muscle of oxygen so those cells die
Ventricular hypertrophy: increase in muscle thickness (causes deep S wave in electrocardiagram)

64
Q

What is fibrillation?

A

Irregular heartbeat
Atria completley lose rhythm/stop contracting properly
Can result in chest pain+ fainting to lack of pulse + death

65
Q

Give key aspects of heamoglobin

A
  • quaternary protein (made from multiple polypeptide chains)
  • each polypeptide lionked to a haem group (FE2+)
  • 4 haem groups, each of which can bind to one oxygen muscle
  • so each human haemoglobin molecule can carry 4 oxygen
66
Q

How does the ability of heamoglobin to uptake/release oxygen differ?

A

Depends on volume of oxygen in surrounding tissue

67
Q

What is partial presssure?

A

The volume of oxygen measured by the relative pressure it contributes to a mixture of gases
Also known as oxygen tension (kPa)
- greater volume of dissolved oxygen, the higher its partial pressure
- lower volume of dissolved oxygen, the lower its partial pressure

68
Q

How is oxygen affinity used in oxygen transport in the body?

A
  • erythrocytes have lots of haemoglobin which as a high O2 affinity
  • haemoglobin addosicates with O2 in the alveoli, because O2 partial pressure is high
  • oxygen diffuses from high partial pressure in alveoli to low partial pressure in blood
  • haemoglobin becomes saturated with oxygen to form oxyhaemoglobin
69
Q

How does oxygen enter respiring cells?

A
  • oxyhaemoglobin carried by erythrocytes to respiring tissues
  • here partial pressure of oxygen is low as O2 is being used in aerobic respiration
  • oxyhaemoglobin gives up oxygen to respiring cells
  • oxygen diffuses from high partial pressure in blood to low partial pressure in tissue
70
Q

What is the oxygen dissociation curve?

A

The amount of O2 binding to haemoglobin a different partial pressures of O2
The % O2 saturation of haemoglobin plotted against partial pressure of O2 in the surroundings

71
Q

Where on the oxygen dissociation curve are respiring tissues and alveoli?

A

Respiring tissues: Left
Alveoli: Right

72
Q

Explain what happens in the alveoli and respiring tissue regarding oxygen affinity and partial pressure

A

Alveoli: High partial pressure of oxygen - so have a high oxygen affinity - so associate oxygen and become saturated
Respiring tissue: Low partial pressure of oxygen - so have a low oxygen affinity - so disassociate oxygen

73
Q

Why is the oxygen disassociation curve S shaped?

A
  • low saturation level of haemoglobin at low partial pressure, so it is difficult for oxygen to associate with haem groups in the centre of the molecules
  • after binding of first oxygen molecule, a slight conformation change is caused in haemoglobin, allowing easier association of 2nd +3rd molecule
  • more difficult for 4th molecule to diffuse in and associate with haem gorup
74
Q

What is the advantage of the oxygen disassociation curve being S shaped?

A
  • haemoglobin needs to pick up oxygen in lungs (where O2 partial pressure is high) and release oxygen at tissues (low O2 partial pressure)
  • if it is hard for a molecule of O2 to associate, it is hard for molecule to disassociate once bound. If its easy for an O2 to associate it is easy for a molecule to disassociate
75
Q

How to structure a typical response to a question of the significance of the oxygen dissociation curve?

A
  1. Location: Where in the body you’re talking about + the O2 partial pressure from the graph
  2. Effect: Explain the effect of partial pressure on haemoglobin’s affinity for oxygen
  3. Consequence: Explain what happens to the oxygen molecule (taken up or released)
76
Q

Name the three ways carbon dioxide is transported and the % of how much is it used

A

1.Dissolved in plasma: 5%
2.Combined with haemoglobin to form carbaminohaemoglobin: 10%
3.Transported in the form of hydrogencarbonate ions (HCO3-)

77
Q

What is the bohr effect?

A
  • higher pCO2 due to more aerobic respiration
  • curve shifts to the right
  • haemoglobin has lower affinity for O2, so haemoglobin dissociates more O2, at a given partial pressure
78
Q

What advantages does the bohr effect/shift provide?

A
  • actively respiring tissue needs more oxygen for aerobic respiration to make ATP
  • actively respiring tissue creates more carbon dioxide
  • lower affinity of haemoglobin for oxygen
  • more O2 released at same partial pressure of oxygen
79
Q

Explain the formation of hydrogen carbonate ions

A

Carbon dixoide + water → carbonic acid (using carbonic anhydrase enzyme)
Carbonic acid → hydrogen carbonate ion + hydrogen ion (through dissociation of H+ ion from carbonic acid)

80
Q

What happens after carbon dioxide moves into the red blood cell?

A
  • CO2 + H20 converted by carbonic anhydrase into carbonic acid
  • carbonic acid dissociates into hydrogen ion + hdyrogen carbonate ions
  • HCO3- carbonate ion diffuses into plasma
  • H+ ion binds with oxyhaemoglobin to release more oxygen + form haemoglobinic acid
  • low CO2 at lungs causes reverse of process
81
Q

How does CO2 lower the affinity of haemoglobin for oxygen?

A
  • it causes H+ ions to be released into the erythrocyte
  • this prevents the pH being lowered, the H+ ions bind to the oxyhaemoglobin and form haemoglobinic acid (this is a buffering effect)
  • this changes the structure of the haemoglobin, meaning more oxygen is released in areas of high rates of aerobic respiration

OCR Biology A Level (20 decks)

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