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A-Level EDUQUAS Biology > Component 3: Animal Transport > Flashcards

Component 3: Animal Transport Flashcards

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1
Q

What are the features of a transport system?

A
  • suitable medium to carry materials
  • a pump to move blood
  • valves to maintain flow in one direction
  • some may have a respiratory pigment
  • some may have a system of vessels to distribute the transport medium all over the body
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2
Q

What is an open circulatory system?

A

Circulatory system where the blood doesn’t move around the body in blood vessels but the fluid bathes in tissues directly whilst being held in the haemocoel (cavity)

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3
Q

What organism is an example for an open circulatory system?

A

Insects:

  • heart (dorsal tube-shaped) pumps blood (haemolymph) out at a low pressure through vessels into a fluid filled cavity (haemocoel)
  • the tissues bathe in the blood directly and an exchange of materials takes place
  • blood then slowly returns to the heart and circulation repeats
  • O2 diffuses directly to tissues from the tracheae, therefore blood doesn’t transport O2 and there’s no respiratory pigment (lack of respiratory gases in blood0
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4
Q

What is a closed circulatory system?

A
  • The blood moves in blood vessels, pumped by muscular heart at high pressure creating a rapid flow
  • tissues aren’t in direct contact with the blood
  • blood contains the respiratory pigment, haemoglobin
  • 2 types of closed systems: single and double
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5
Q

What is a single circulation system?

A

In a single circulation system the blood moves through the heart once in its passage around the body

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6
Q

Earthworm single circulation system

A

In earthworms the blood moves forwards in dorsal vessel and back in the ventral vessel, five pairs of pseudohearts pump the blood from the dorsal to the ventral vessel (keep it moving)

  • organs aren’t in direct contact with blood
  • respiratory gases are transported in blood
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7
Q

Fish single circulation system

A
  • heart ventricle pumps the deoxygenated blood to the gills
  • oxygenated blood is carried to the rest of the body (tissues)
  • deoxygenated blood returns to the heart
  • blood travels through the heart once for each circuit
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8
Q

What is a double circulation system?

A

The blood passes twice through the heart for each complete circuit of the body (have 2 atria and 2 ventricles)

  • Mammals have double circulations as an advantage is that the blood leaving the lungs will be fully oxygenated
  • blood entering the lungs can enter at a lower pressure (high pressure would damage the delicate tissue)
  • blood pressure reduced in the lungs and the heart increases pressure again to pump it the rest of the body (delivered quickly)
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9
Q

What are the parts of the heart?

A

ON THE RIGHT
superior vena cava & inferior vena cava
right ventricle
right atrio-ventricular valve (tricuspid)
right ventricle
right semi-lunar valve
pulmonary artery

ON THE LEFT
pulmonary veins
left atrium
left atrio-ventricular valve (bicuspid)
left ventricle
left semi lunar valve
aorta
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10
Q

What is the role of plasma?

A
  • Fluid which blood cells and dissolved solutes are suspended within and carriers them around the body
  • important role in heat distribution
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11
Q

What is function and characteristics of erythrocytes?

A
  • contain red oxygen carrying protein haemoglobin
  • have a biconcave shape to increase surface area to volume ratio
  • no nucleus to allow them to carry more haemoglobin
  • are flexible, allowing them to squeeze through narrow capillaries
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12
Q

What is the function and characteristics of leucocytes?

A
  • are involved in preventing and fighting infection
  • have a nucleus
  • come in several different types: lymphocyte, monocyte and eosinophil
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13
Q

Describe the characteristics of the mammalian heart

A
  • 4 chambered pumps for both pulmonary and systemic circulatory systems
  • double pump working synchronously keeping oxygenated and deoxygenated blood separated
  • cardiac muscle is myogenic - contractions are initiated within the muscle itself
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14
Q

What is the function of the septum?

A
  • separates the 2 sides of the heart
  • stops oxygenated blood and deoxygenated blood mixing
  • ensures oxygenated blood gets to the rest of the body and deoxygenated blood gets to the lungs
  • allows pressure differences to be maintained on each side as if there was a hole in the heart there would be a drop in blood pressure
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15
Q

What is meant by systole and diastole?

A

systole - a period of contraction
diastole - period of relaxation
(normally diastole is longer than systole)

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16
Q

What is the sequence of the cardiac cycle?

A
  1. atria fills with blood, all chambers are relaxed
  2. pressure inside atria increases, blood trickles into ventricles, pushes atrioventricular valves open
  3. atria walls contract (atrial systole) and atria empty as rest of blood is forced into ventricles
  4. following a short delay to allow full contraction of atria, the ventricles contract (ventricular systole), atria relax
  5. ventricle walls contract from the bottom up, reducing the volume and increasing the pressure
  6. atrioventricular valves are pushed shut to prevent backflow (the ‘lub’ sound)
  7. pressure in the ventricles is greater than pressure in aorta and pulmonary artery, this pushes open the semilunar valves in the arteries and forces blood out of the heart and into arteries
  8. ventricles relax, pressure falls and semilunar valves shut (‘dub’ sound)
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17
Q

How do the valves work?

A

Open…

  • valves are pushes open when the pressure above the valve is greater than below it
  • atrioventricular opens when the pressure in the atrium is greater than the ventricle
  • semilunar opens when the pressure in the ventricle is greater than the artery

Closed…
- the valves are pushed closed to prevent the backflow of blood

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18
Q

What is the sequence of the electrical control of the heart?

A
  1. sinoatrial node (SAN) initiated an electrical impulse
  2. this spreads over the walls of the atria causing them to contract (atrial systole), the atria contract simultaneously
  3. it’s prevented from spreading to the ventricles by a thin layer of connective tissue (non-conductive)
  4. the electrical impulses reach the atrioventricular node (AVN)
  5. the electrical impulse is delayed through this node which allows the complete contraction of atria before the ventricles begin to contract
  6. the electrical impulse then travels down a highly conductive tissue in the septum called the bundle of His
  7. as it reaches the apex of the ventricles it causes the ventricles to contract
  8. it then travels through the purkinje fibres up the side of the ventricles from bottom upwards (ventricular systole) and blood is forced up into the arteries
  9. the electrical impulse is then terminated as there is no more conductive tissue, the heart then goes into a period of relaxation called diastole
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19
Q

What are artificial pacemakers?

A
  • devices implanted for people who have a heart electrical conduction system that isn’t working properly
  • pace makers monitor the heart’s electrical activity and stimulate ventricles/atria to contract when necessary
  • impulses transmitted down electrodes implanted in muscular-walls
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20
Q

What are the different waves on an electrocardiogram (ECG)?

A
  • P wave is the first part of the trace, shows the voltage change generated by SAN, associated with atria contraction (atrial systole)
  • QRS complex shows the contraction of the ventricles (ventricle systole)
  • T wave shows electrical activity during recovery (diastole)
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21
Q

What is an ECG?

A
  • An electrocardiogram
  • detects electrical activity in heart during cardiac cycle by electrodes placed on skin
  • signals can then be shown on a chart recorder
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22
Q

Describe the roles of the SAN, AVN and bundle of His in the cardiac cycle?

A

SAN
- initiated the cardiac cycle/wave of excitation
- causes atria to contract
AVN
- passes impulse down purkinje fibres
- results in delay
Bundle of His
- carries impulse from AVN down to apex of the heart
- causes ventricles to contract from apex upwards

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23
Q

What is the condition of the atria and ventricles during each phase of the cardiac cycle?

A

Condition of Atria
Atrial systole: contracted
Ventricular systole: relaxed
Diastole: relaxed

Condition of ventricles
Atrial systole: relaxed
Ventricular systole: Contracted
Diastole: relaxed

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24
Q

What is the condition of the atrioventricular valves and the semi lunar valves during each phase of the cycle?

A

Condition of atrioventricular valves
Atrial systole: open
Ventricular systole: closed
Diastole: open

Condition of semi lunar valves
Atrial systole: closed
Ventricular: Open
Diastole: closed

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25
Q

Where is the SAN?

A

top left of the right atrium

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26
Q

What is the function of the coronary arteries?

A

To supply oxygen and nutrients to the cardiac heart muscle to contract

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27
Q

What is pulmonary circulation?

A

lungs

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28
Q

What is systemic circulation?

A

rest of the body

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29
Q

What are the layers of blood vessels?

A 
lumen
tunica interna (made of squamous endothelial cells)
tunica media (made of smooth muscle and and elastic tissue)
tunica externa (collagen)
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30
Q

Why do arteries have thicker walls than veins?

A

Have to withstand high pressure because of contractions of the left ventricle

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31
Q

What is the structure of the arteries and how does that relate to its function?

A

Thick walls made of collagen (tunica externa):
- provides resistance against high pressured blood travelling away from the heart
Lots of elastic tissue in wall of tunica media:
- allows the blood vessels to stretch to accommodate a surge of blood from the ventricles and recoil to maintain pressure
Smooth muscle in arteriole wall:
- allows vasoconstriction to reduce the diameter of the lumen and so reduce blood supply to organs (e.g. skin)

32
Q

What is the structure of capillaries and how does that relate to its function?

A

The wall is a single endothelium cell thick and there’s no elastic tissue
- provides a short diffusion pathways for exchange of molecules
Small diameter of lumen
- causes friction with walls and slows the blood flow, enhancing the ability to exchange materials with the surrounding tissue by diffusion
Large number present in the body
- provides a large SA for exchange of molecules

33
Q

What is the structure of veins and how does that relate to its function?

A

Little elastic tissue in tunica media therefore has relatively thin walls
- blood is travelling at a low pressure and there is less need for these structures
Large diameter of lumen
- aids in returning low pressure blood to the heart
Valves
- prevents backflow of blood

34
Q

Describe the pressure of the blood coming out of the heart into arteries?

A
  • Blood is at a high pressure as it has to be pumped out of the left ventricle
  • The pressure is maintained due to the elastic tissue of the arteries
  • The fluctuations are due to the contraction and relaxation of the the left ventricle of the heart (rhythmical)
35
Q

Describe the pressure in the arteries?

A
  • High pressure because of contractions of the left ventricle (lowers slightly as it gets further away from the heart)
  • The high pressure is maintained due to the elastic tissue recoil in the tunica media
  • Pressure can change depending on wether the smooth muscle is contracted or relaxed
  • friction with vessel walls causes progressive pressure drop
36
Q

Describe the pressure in the capillaries?

A
  • Blood is at a much lower pressure as it is further away from the heart
  • There are many more capillaries than arterioles therefore there’s a greater total cross sectional area over which the pressure is spread
  • There pressure drops further as there is a loss of fluid from the blood to the tissue
  • friction with vessel walls causes progressive pressure drop
37
Q

Describe the pressure in the veins?

A
  • Blood is still low as it’s further away from the heart
  • There is some residual pressure from the heart
  • The contraction of skeletal muscle aids in returning blood to the heart (non rhythmical)
  • pressure is low in the veins but is increased by massaging effect of muscles
38
Q

Describe and explain the relationship between total cross sectional area and the velocity of flow?

A
  • as the total cross sectional are increases the velocity of the flow decreases
  • the pressure is spread out over a larger area as there are progressively more blood vessels as go from an artery to a capillary bed
  • there will also be increasingly more friction with the walls of the blood vessel which will reduce flow and pressure
39
Q

Describe the blood flow in the veins

A
  • no longer influenced by the contractions of the heart and is under very low pressure
  • gets back to the heart by ….
    · gravity for organs above the heart
    · the venous pump produced by action of skeletal muscle and negative pressure in thorax produced by inspiration for organs below heart
40
Q

What is pulse?

A
  • a pulse is due to a surge of blood causing the artery wall to stretch and bulge
  • pulse corresponds with ventricular contraction
  • measured in bpm
  • age, smoking, diet, exercise, stress and excitement all affect pulse rate
  • average resting pulse rate is 70 bpm
41
Q

What is blood pressure?

A

measurement of:

  • systolic pressure (ventricular contraction)
  • diastolic pressure
  • measured by a sphygmomanometer
42
Q

How are capillaries efficient at exchanging materials?

A

Low velocity (narrow lumen diameter, friction and large cross sectional area all slow down blood flow) and very thin walled vessels with pores enhance their ability to exchange materials with the surrounding tissue and thus cells

43
Q

What is tissue fluid and what is the role?

A

Plasma without plasma proteins or red blood cells and formed by leakage from capillaries

  • bathes all cells
  • transports O2 and nutrients from blood to cells and CO2 and waste products from cells to blood
44
Q

What other molecules are present in tissue fluid and lymph?

A

WBC, water, ions, glucose, antibodies and lipid

45
Q

What is lymph?

A

90-99% of tissue fluid is forced out and returns to venous end of capillary bed, the remaining tissue fluid removed by drainage into the lymphatic system becomes lymph
- same composition but contains more lipids and CO2 and less O2 and nutrients

46
Q

What are lymph vessels?

A

Lymph vessels are blind-ended and only allow fluid to enter, they form a drainage network and return lymph to the bloodstream via the subclavian vein

47
Q

What are lymph nodes?

A

Lymph nodes are situated in the armpit, groin, neck and groin
- these hold many lymphocytes (a type of WBC) which intercept bacteria and viruses and help prevent spread of microbial infection in the body

48
Q

What are problems associated with lymph?

A
  • low blood proteins can affect capillary filtration which may result in fluid retention in tissues (oedema) e.g. Kwashiorkor
  • If lymph vessels become blocked, swelling can occur in the affected limbs due to accumulation of tissue fluid
49
Q

What is the exchange in capillary bed at the arteriole end?

A
  • Hydrostatic pressure is high due to contraction of the left ventricle (the water potential of the blood is lower that the tissue fluid so water will want to enter the blood by osmosis)
  • However the hydrostatic pressure is higher than the osmotic pressure and therefore there is net movement of fluid out of the capillary and into the tissue space
  • The tissue fluid will now be high in glucose, oxygen, ions and amino acids
  • However the blood will still contain the RBC, WBC and the large plasma proteins
50
Q

Describe the exchange in the capillary bed?

A
  • The cells will take in oxygen and glucose by diffusion and use it for aerobic respiration
  • The amino acids will be used in the cell to make new proteins
  • This ensures a concentrated gradient is maintained
  • Carbon Dioxide and any other waste products will diffuse into the tissue fluid
51
Q

Describe the capillary bed exchange at the venous end?

A
  • Hydrostatic pressure is lower due to loss of fluid from the capillary
  • The water potential of the blood is lower than the tissue fluid due to the retention of the large plasma proteins in the blood
  • So water will want to enter the blood by osmosis
  • Now the osmotic pressure is greater than the hydrostatic pressure therefore there is net movement of fluid into the capillary by osmosis
  • The fluid returning into the capillary is high in waste products including carbon dioxide
  • This will be returned to the heart via the vena cava and then to the lungs via the pulmonary artery
52
Q

Describe the lymphatic system in terms of capillary bed exchange?

A
  • Normally 90-99% of the tissue is returned to the capillary at the venous end
  • The excess drains into the lymphatic system
  • This fluid travels in the thoracic duct to the subclavian vein where it’s returned to the blood
53
Q

How does haemoglobin carry oxygen?

A

as oxyhaemoglobin (HbO8)

54
Q

Where does haemoglobin pick up oxygen and leave it?

A
  • Picks up oxygen in tissues with high a high partial pressure of oxygen (lungs) so haemoglobin can become saturated with oxygen
  • RBC carry oxygen as oxyhaemoglobin to respiring tissues (e.g. muscles) where the partial pressure of oxygen is low, as oxygen is being used up in respiration so oxyhaemoglobin dissociates
55
Q

What is meant by affinity?

A

The degree to which two molecules are attracted to each other

56
Q

What is meant by cooperative binding?

A

The increasing ease with which haemoglobin binds its second and third oxygen molecules as the shape haemoglobin molecule changes

57
Q

Describe the shape of the oxygen dissociation curve and what the curve can show

A

Sigmoid shape

  • at a very low ppO2 it’s difficult for O2 to associate with haemoglobin but as ppO2 increases it becomes increasingly easier for haemoglobin to associate
  • the oxygen affinity for haemoglobin for oxygen is high, at high ppO2 oxyhaemoglobin doesn’t dissociate
  • oxygen affinity reduces as the partial pressure of oxygen decreases, oxygen is readily released meeting respiratory demands (a very small decrease in pp leads to lots of dissociation)
58
Q

What is the Bohr effect?

A

If the CO2 concentration increases more O2 is available

  • This means that when exercising the muscles can be supplied with more O2 for continued respiration
  • When CO2 is present more O2 from oxyhaemoglobin dissociates into the respiring tissues that would normally be released at that ppO2
  • so the curve moves to the right
59
Q

What is the oxygen dissociation curve for foetal haemoglobin?

A
  • the foetus is reliant on the mother’s blood for everything is needs (e.g. O2) however the mother’s blood will not be fully oxygenated by the time it reaches the placenta
  • foetal haemoglobin has a slightly different structure than adult haemoglobin which means it has a higher affinity for oxygen than the mother’s
  • in the placenta the foetal haemoglobin binds to oxygen at a lower ppO2 than the mother’s would
  • at a particular ppO2 foetal Hb will be more saturated than adult Hb would be, curve is shifted to the left
60
Q

What is the oxygen dissociation curve for myoglobin?

A
  • diving mammals need to store enough O2 to last them through long dives
  • haemoglobin is not well suited for this as Hb will dissociate O2 immediately for aerobic respiration
  • myoglobin has a very high affinity for oxygen (more saturated at any ppO2)
  • this means that oxymyoglobin will not dissociate until the ppO2 is very low (e.g. during vigorous exercise)
  • curve shifted FAR to the left
61
Q

What is the oxygen dissociation curve for llamas?

A
  • live at high altitudes meaning that the oxygen partial pressure in the atmosphere decreases
  • llama possess haemoglobin which associates with oxygen more readily in the lungs (higher affinity at all oxygen partial pressures)
  • the curve is shifted to the left
62
Q

What is the oxygen dissociation curve for lugworms?

A
  • live in a low oxygen environment
  • has a low metabolic rate so haemoglobin only dissociates for oxygen at really low ppO2
  • curve is shifted to the left
63
Q

What are the 3 ways CO2 is transported in the blood?

A
  1. Dissolved in the plasma
  2. Combined with haemoglobin to form carbomino-haemoglobin
  3. Transported as hydrogen carbonate ions (HCO3-)
64
Q

Describe the formation of hydrogen carbonate ions?

A
  • CO2 diffuses into the plasma from the respiring cells then into the red blood cell cytoplasm
  • CO2 reacts with water to form carbonic acid which is catalysed by carbonic anhydrase
  • H2CO3 is unstable so dissociates into hydrogen ions and hydrogen carbonate ions
65
Q

What happens to hydrogen carbonate ions?

A
  • ions diffuse out of the RBC into the blood plasma
  • to maintain the correct charge inside the red blood cell Cl- diffuses into the red blood cell, this is known as ‘chloride shift’
66
Q

What happens to the H+ ions?

A
  • H+ ions would lower the pH and affect enzyme activity so Hb acts a s a buffer by binding to H+ to form haemoglobinic acid:
    H+ + HbO8 -> HHb + 4O2
  • H+ ions have a higher affinity for Hb than O2 so O2 is pushed off into tissue fluid and diffuses into the cells
  • H+ ions cause Hb to be less saturated with O2 (Bohr shift)
  • The more cells respire the more CO2 is produced, more H+ ions push O2 off and therefore the cells that require more oxygen receive it
67
Q

What are all the major arteries and veins in the body?

A

Head and neck: carotid artery & jugular vein
Liver: hepatic artery & vein
Gut: gastric and mesenteric arteries & hepatic portal vein (leads to liver)
Kidneys: renal artery & vein
Legs: iliac artery & vein

68
Q

Describe the difference between a single and double circulatory systems and explain why a double system is more efficient (2 marks)

A
  • In single systems there is one circuit and in double system there are 2 separate circuits (blood passes through the heart twice compared to once)
  • it allows oxygenated blood to be delivered to organs under high pressure
69
Q

There are well developed circular muscles in the arteries. Give 2 functions of these circular muscles

A
  1. contract and prevent dilation at ventricular systole

2. vasoconstriction

70
Q

Explain the advantage of the slow rate of conduction through AVN (2 marks)

A
  • delays contraction of ventricles

- until after the atria have contracted

71
Q

Suggest one advantage of the high rate of conduction in the Purkyne fibres which carry impulses through the walls of the ventricles

A

Rapid contraction of ventricles

72
Q

Explain why narrowing of the coronary arteries could lead to the heart not contracting?

A

oxygen/glucose doesn’t reach the cardiac muscle so muscle is unable to respire aerobically

73
Q

Suggest how people become adapted to living at very high altitudes

A

increase in red blood count

74
Q

Why do runners train at high altitudes?

A
  • increase in red blood count
  • more RBC in general circulation
  • more oxygen is able to be supplied to muscles and tissues
  • aerobic respiration can continue for longer (anaerobic respiration not required)
75
Q

Suggest why people with reduced blood pCO2 commonly feel tired

A
  • Increased affinity for haemoglobin for oxygen (decreased dissociation of oxyhaemoglobin)
  • less oxygen is available for respiration

A-Level EDUQUAS Biology (24 decks)

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