Animal transport Flashcards

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1
Q

why do animals need circulatory systems?

A
  • hormones and enzymes often produced in one part of the body and required in another part
  • circulatory systems transport these substances
  • eg. digested food, absorbed in intestines is required by all cells in body
  • waste products of metabolism produced by al cells, need to be disposed of in particular part of body
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2
Q

components of a circulatory system

A
  • heart
  • fluid substances are transported in
  • vessels fluids can flow in
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3
Q

open circulatory system

A
  • heart pumps haemolymph through short vessels into large cavity called haemocoel
  • in the haemocoel, haemolyph directly bathes organs enabling diffusion of substances
  • when heart relaxes, haemolymph sucked back via pores called ostia
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4
Q

closed circulatory system

A
  • blood is fully enclosed within vessels
  • from heart, blood pumped through progressively smaller vessels, in capillaries, substances diffuse in and out of blood and into cells
  • blood returns to heart
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5
Q

single circulatory system

A
  • blood passes through two- chambered heart just once per complete circuit of the body
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6
Q

double circulatory system

A
  • blood passes through four-chambered heart twice per complete circuit of the body
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7
Q

pulmonary circulation

A
  • consists of all vessels involved in transporting blood between heart and lungs
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8
Q

systemic circulation

A
  • consists of all vessels involved in transporting blood between heart and body, not lungs
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9
Q

advantage of single circulatory system

A
  • less complex, does not require complex organs
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10
Q

disadvantages of single circulatory system

A
  • low blood pressure - slow movement of blood
  • activity level of animals tends to be low
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11
Q

advantages of double circulatory system

A
  • heart can pump blood further around body
  • high pressure
  • fast blood flow `
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12
Q

characteristics of arteries and arterioles

A
  • carry blood under high pressure
  • narrow lumen - maintains pressure
  • thick elastic and muscle layers allow vessel to expand with heart beat then recoil
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13
Q

how are arterioles different from arteries?

A
  • arterioles have more muscle and less elastic fibres, little pulse surge, constrict and dilate to move blood
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14
Q

capillaries characteristics

A
  • lumen only one blood cell thick - ensures red blood cells travel single file
  • substances exchanged from blood cells to surrounding tissue through gaps in endothelium
  • large surface area
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15
Q

adaptations of capillaries

A
  • large surface area - allow diffusion of substances in and out of capillaries
  • small cross-sectional area - reduces rate of blood flow from artery supplying them
  • endothelium is one cell thick - short diffusion pathway
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16
Q

veins characteristics

A
  • no pulses as blood pressure is low - pressure is lost as blood moves around body
  • walls conatin lots of collagen and few elastic fibres and muscle - greater proportion of vessel is lumen
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17
Q

venules charcateristics

A
  • no elastin fibres or smooth muscles
  • several venules split from one vein
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18
Q

how do breathing movement help blood flow?

A
  • chest movements help movement of blood
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19
Q

how does blood flow through veins?

A
  • series of valves and contraction of skeletal muscle
  • skeletal muscle contracts and blood is forced towards heart forcing valves open
  • as skeletal muscles relax, blood pushes back against valves causing them to close
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20
Q

functions of blood

A
  • transport
  • defence
  • thermoregulation
  • maintaining pH of bodily fluids
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21
Q

specialised features of erythrocytes

A
  • flattened biconcave disc shape - large surface area to volume ratio for gas exchange
  • large amount of harmoglobin - oxygen transport
  • no nucleus or organelles - maximises space for haemoglobin and oxygen
  • larger diameter than capillary - slows blood flow to enable diffusion
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22
Q

why does blood have a low water potential?

A
  • large proteins eg. albunium - dissolved in blood plasma
  • water tends to move into blood from surrounding tissues by osmosis
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23
Q

what does high hydrostatic pressure in arteriole end of a capillary cause?

A

water is forced out of capillary

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24
Q

what does high oncotic pressure at the venule end of a capillary cause?

A
  • there is low water potential in blood bc
    water has been forced out
  • causes water to move back into capillary
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25
Q

what happens when not all tissue fluid returns to the capillaries?

A
  • excess drains to the lymphatic system through valves and nodes where it forms lymph
  • lymph is a pale yellow fluid similar to tissue fluid but contains more lipids
  • lymphatic system drains into the circulatory system via the thoracic duct
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26
Q

what would happen without the lymph system?

A
  • there would be a build up of lymph fluid in tissues called oedema, making them swell
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27
Q

what does the lymphatic system consist of?

A
  • lymphatic capillaries and lymph vessels with valves
  • lymph nodes - sac-like organs that trap pathogens and foreign substances and contain large numbers of white blood cells
  • lymphatic tissue - in spleen, thymus, tonsils - contain large amounts of white blood cells
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28
Q

how does exchange occur at respiring cells?

A
  • tissue fluid surrounds cells
  • tissue fluid contains small molecules that leave blood plasma - glucose, amino acids, fatty acids, ions, oxygen
  • cells take in oxygen and nutrients from tissue fluid and release metabolic waste
29
Q

where is the semi-lunar valve?

A

going from the ventricles to the pulmonary artery or aorta

30
Q

where are the atrioventricular valves?

A

going from the atrium to the ventricles

31
Q

cardiac muscle

A
  • muscle in the heart
  • contracts involuntarily - myogenic
  • made up of cells connected by cytoplasmic bridges - enables electrical impulses
32
Q

cardiac cycle - names of stages

A
  • atrial systole
  • ventricular systole
  • diastole
33
Q

atrial systole

A
  • muscles of atria contract
  • pressure in atria increases
  • tricuspid (right side) and bicuspid (left side) atrioventricular valves open, allowing blood into ventricles
  • pressure decreases
  • lasts about 0.1 sec
  • depolarisation
34
Q

ventricular systole

A
  • muscles of ventricles contract
  • pressure in ventricles increases
  • tricuspid and bicuspid AV valves close
  • semi-lunar valves in aorta and pulmonary arteries open
  • pressure decreases
  • lasts about 0.3 sec
35
Q

diastole

A
  • pressure in ventricles decreases
  • semi-lunar valves close
  • all heart muscles relax
  • blood flows into atria from vena cava and pulmonary vein
  • blood pressure in atria and ventricles remains low
36
Q

functions of valves and how do they work?

A
  • prevent backflow in heart
  • controlled by pressure changes in heart chambers
  • high pressure behind valves forces it open
  • high pressure in front of valves closes it
37
Q

cardiac output

A
  • amount of blood pumped around body
  • stroke volume x heart rate
38
Q

what does it mean that the cardiac muscle is myogenic?

A

it has its own intrinsic rhythm - around 60 bpm

39
Q

what makes the heart myogenic?

A
  • muscle cells (myocytes) in the heart are slightly charged - polarised
  • when the charge is reversed they are depolarised
40
Q

sinoatrial node

A
  • in right atrium
  • acts as heart’s pacemaker
  • initiates electrical impulse that spreads across both atria causing them to contract
  • blood forced through bicuspid and tricuspid valves into ventricles
  • (atrial systole)
41
Q

atrioventricular node

A
  • impulse from SAN reaches AVN and after a delay of 0.1 sec, impulse is transmitted along specialised muscle fibres called bundle of His, then reaches apex of heart
  • delays impulse allowing ventricles to fill and atria to fully contract
42
Q

bundle of His

A
  • electrical impulse travels down it from the AVN so the ventricles contract from the bottom up
  • insulating layer prevents contractions until at the apex
  • ensures all blood gets pushed out of ventricles
43
Q

Purkinje fibres

A
  • wave is transmitted from bundle of His through Purkinje fibres to myocytes in walls of ventricles
  • causes them to contract and forcing blood out of ventricles into atria
44
Q

repolarisation

A
  • during diastole the heart relaxes and the chambers fill with blood
  • nodes become polarised - positive charge builds up on inside of node and negative charge on outside
45
Q

brachycardia

A

slow heart beat, less than 60bpm

46
Q

tachycardia

A

fast heart rate, more than 100bpm

47
Q

ectopic beat

A

extra beats followed by gaps

48
Q

atrial fibrillation

A

irregular rhythm

49
Q

what makes the ‘lub-dub’ heart sounds?

A
  • ‘lub’ - atrio-ventricular valves closing (right and left side at same time)
  • ‘dub’ - semi-lunar valves closing
50
Q

what is the P wave in an ECG?

A
  • wave of depolarisation from SAN across artia causing atrial systole
  • smallest bump at very start of ECG
51
Q

what is the PR interval in an ECG?

A
  • time taken for wave of depolarisation to move from the SAN to the AVN and then ventricles
  • measured from start of P wave to start of QRS complex
  • flat line between smallest bump and big spike
52
Q

what is QRS complex in an ECG?

A
  • wave of depolarisation spread across ventricles causing ventricular systole (contraction)
  • the largest spike
53
Q

ST segment in ECG

A
  • interval between end of ventricular systole and start of ventricular repolarisation
  • measured from end of QRS complex to start of T wave
  • flat line after big spike
54
Q

T wave in ECG

A
  • repolarisation of ventricles during diastole
  • last bump
55
Q

how to measure heart rate from an ECG

A
  • measure distance between two identical points
  • work out how many fit into 60 sec
56
Q

affinity for oxygen

A

tendency to combine with oxygen

57
Q

partial pressure of oxygen

A

measure of concentration/proportion of oxygen - greater concentration of oxygen dissolved in the air, higher partial pressure
- pO2

58
Q

describe the oxygen dissociation curve

A
  • low partial pressure - low proportion of oxyhaemoglobin, most haemoglobin only take up one oxygen or none
  • once Hb has picked up one oxygen, its oxygen affinity increases - small increase in partial pressure leads to large increase in oxyhaemoglobin
  • once high saturation reached, molecules unable to take on more oxygen, rises in partial pressure make less difference so graph levels out
  • ‘S’ shaped but flatter at top
59
Q

partial pressure in lungs and effects

A
  • high partial pressure (12-13 kPa)
  • haemoglobin has 95-97% saturation
60
Q

partial pressure in respiring tissues and effects

A
  • low partial pressure (1-4 kPa)
  • haemoglobin has 20-25% saturation
61
Q

what is the Bohr shift?

A
  • shows the effect of CO2 on haemoglobin saturation of oxygen
  • the second line is drawn to the right of the original
62
Q

what % of CO2 produced by respiring cells is transported in blood plasma, carboaminohaemoglobin and hydrogen carbonate ions?

A

blood plasma - 5%
carbaminohaemoglobin - 20%
hydrogen carbonate ions - 75-80%

63
Q

transport of carbon dioxide in carbaminohaemoglobin

A
  • each of haemoglobins’ 4 polypeptide chains has a free amino group
  • each amino group can react with a molecule of carbon dioxide
  • carbon dioxide + haemoglobin<—–reversible—–> carbaminohaemoglobin
64
Q

carbon dioxide transport as hydrogen carbonate ions in blood plasma

A
  • when CO2 diffuses into RBC it forms carbonic acid - ensures level of CO2 low to maintain conc. gradient
  • carbonic acid dissociates - hydrogen carbonate ion and hydrogen ion
  • hydrogen carbonate ion diffuses out RBC into blood plasma - causes charge imbalance
  • negative chloride ion diffuses into RBC - chloride shift - prevents charge imbalance
  • hydrogen ions bind to haemoglobin to prevent pH of blood falling (haemoglobonic acid) - haemoglobin acts as a buffer
  • at the lungs hydrogen carbonate ions diffuse back into RBC in exchange for chloride ions
  • hydrogen carbonate ions combine with H+ to reform carbonic acid which is broken down by carbonic anhydrase forming CO2
  • CO2 diffuses out of RBC into blood plasma - CO2 can be exhaled through lungs
65
Q

equation to form carbonic acid

A

CO2 + H2O <—carbonic anyhydrase—> H2CO3

66
Q

equation to form hydrogen carbonate ions

A

H2CO3 <——> HCO3- + H+
carbonic acid<—>hydrogen carbonate + hydrogen ion

67
Q

how is fetal haemoglobin different form adult haemoglobin?

A
  • fetal haemoglobin - higher affintiy for oxygen
  • helps maximise oxygen uptake from mother’s blood as it cannot breathe on its own
  • mother’s blood would lose some oxygen due to her respiring so needs to have a high affinity
68
Q

what creates oncotic pressure?

A
  • plasma proteins in the blood are too large to fit through the endothelium of the capillary
  • this creates a lower water potential in the capillary than the tissue fluid
  • water moves by osmosis into the capillary raising the oncotic pressure