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biology > C8 - Transport in animals > Flashcards

C8 - Transport in animals Flashcards

1
Q

Why do some organisms require a specialised transport system?

A

-High metabolic demands so diffusion is insufficient
-Small SA:V ratio
-Molecules made in one place but required in another

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2
Q

What features do circulatory systems have in common?

A

-Liquid transport medium that circulates
-Vessels to carry transport system
-Pumping mechanism to move fluid
(-Valves)

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3
Q

What is a circulatory system?

A

Transport system of an animal

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4
Q

What is a mass transport system

A

Transport system where substances are transported in a mass of fluid

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5
Q

What is an open circulatory system?

A

Circulatory system with a heart but few vessels to contain the transport medium

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6
Q

Describe the circulation in an open circulatory system?

A

Transport medium pumped from heart to body cavity (haemocoel)
Under low pressure in haemocoel and in direct contact with cells and tissues enabling exchange
Transport medium returns to heart

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7
Q

Which animals have open circulatory systems?

A

Invertebrate animals

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8
Q

What is a closed circulatory system?

A

Circulatory system where blood is enclosed in blood vessels and does not come in direct contact with cells of the body beyond blood vessels

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9
Q

Which animals have closed circulatory systems?

A

Vertebrate

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10
Q

What is a single closed circulatory system?

A

Circulatory system where blood flows through the heart and is pumped out to travel around the body before returning

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11
Q

What is a double closed circulatory system?

A

Circulatory system where blood travels twice through the heart for each complete circulation of the body

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12
Q

How do nutrients in blood reach cells in a single closed circulatory system?

A

Passes through two sets of capillaries
1st set- exchanges O2 and CO2
2nd set- substances exchanged between capillaries and cells

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13
Q

What are the cons to a single closed circulatory system?

A

BP drops due to passing through two sets of capillaries
Blood returns to heart slowly

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14
Q

How do nutrients in blood reach cells in a single closed circulatory system?

A

Blood pumped form hearts to lungs to exchange O2 and CO2 and then returns to heaty
Blood flows through heart and is pumped to rest of body before returning to heart

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15
Q

What are the positives to a double closed circulatory system?

A

Only passes through one set of capillaries
High pressure blood allows fast blood flow to heart and body

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16
Q

What are the three different components in blood vessels?

A

-Elastin fibres: can stretch/recoil providing flexibility
-Smooth muscle: contracts/relaxes with change in lumen size
-Collagen: provides structural support maintaining shape and volume

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17
Q

What blood do arteries carry?

A

High pressure oxygenated blood
EXCEPT for pulmonary artery and umbilical artery

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18
Q

Describe the structure of arteries

A

Walls contain thick layer of elastic fibres, smooth muscle and collagen
Smooth lining (endothelium)
Small lumen

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19
Q

What is the role of elastic fibres?

A

-Enables arteries to withstand force of blood being pumped
-Enables arteries to stretch to take larger blood volume
-In between pumps of heart, elastic fibres recoil, helps even out surges of blood to give continuous flow

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19
Q

What does the smooth lining enable?

A

Blood flows easily over it

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19
Q

What is the role of arterioles?

A

Link arteries to capillaries

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20
Q

Structure of arterioles compared to arteries?

A

More smooth muscle and less elastin in walls as they have little pulse surge
Can constrict/dilate

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20
Q

What is vasoconstriction?

A

Smooth muscle wall of arteriole constricts decreasing blood flow through capillaries

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21
Q

What is vasodilation?

A

Smooth muscle wall of arteriole relaxes increasing blood flow through capillaries

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21
Q

What are capillaries

A

Microscopic blood vessels linking arterioles with venules

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22
Q

Describe structure of capillary

A

Very small lumen (fits singular RBC)
Capillary wall made of endothelial cells
Gaps between cells are relatively large

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22
Q

How are capillaries adapted for their role?

A

-Large SA for diffusion
-Total cross sectional area of capillary is greater than artery allowing BP to fall, to increase time for diffusion
-Walls are single endothelial cell thick so short diffusion distance

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23
Q

What blood do veins carry?

A

Low pressure deoxygenated blood
EXCEPT pulmonary vein and umbilical vein

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24
Q

Describe the structure of veins

A

-Thin walls containing lots of collagen, smuscle and little elastic fibre
-Wide lumen and smooth endothelium lining so blood flows easy
-Valves

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25
Q

Compare structure of venules to veins

A

Very thin walls with just smooth muscle

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26
Q

How are veins adapted to overcome prevent backflow

A

-Have one way valves at intervals: flaps/infoldings of inner lining, valves close if blood flows backwards
-Valves prevent backflow when muscles relax
-Breathing movements act like pump

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27
Q

What is blood consist of?

A

Yellow liquid, plasma, which contains many substances dissolved

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28
Q

What are the functions of blood

A

Transport of:
O2
CO2
Digested food from small intestine
Nitrogenous waste products to excretory organs
Food molecules
Platelets
Cells and antibodies

-Maintenance of steady body temperature
-Buffer: minimising pH changes

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29
Q

What is tissue fluid?

A

Solution surrounding the cells of multicellular animals

30
Q

What is hydrostatic pressure?

A

Pressure created by water in an enclosed system

31
Q

What is oncotic pressure?

A

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

32
Q

What causes oncotic pressure?

A

Plasma proteins (albumin) cannot pass through capillary wall
Causes low water potential in blood in capillaries
Causes water to move into blood by osmosis

33
Q

What happens at the arterial end of the capillary?

A

Hydrostatic pressure is higher than oncotic pressure, so fluids forced out capillary
Fluid fills space between cells and is now tissue fluid

34
Q

What happens at the venous end of the capillary?

A

Hydrostatic pressure falls as fluid moved out
Lower than oncotic pressure, so fluid moves into capillary
Fluid fills space between cells and is now tissue fluid

35
Q

What is lymph?

A

Modified tissue fluid that is collected in the lymph system

36
Q

Difference between lymph and plasma/tissue fluid

A

Less oxygen
Fewer nutrients
Contains fatty acids

37
Q

Where does tissue fluid that does not return to the capillaries go?

A

Lymph capillaries

38
Q

What is the structure of the lymph system

A

Lymph capillaries join to form larger vessels
Fluid transported by squeezing of body muscles
One-way valves are present to prevent backflow
Returns to blood , flowing into left and right subclavian vein

39
Q

What role does the lymphatic system play in the body?

A

Defence mechanism
-Lymphocytes build up in lymph nodes
-Lymph nodes intercept bacteria and other debris from lymph which are ingested by phagocytes

40
Q

What are enlarged lymph nodes a sign of?

A

Body is fighting an invading pathogen

41
Q

Where are erythrocytes formed?

A

Red bone marrow

42
Q

What do erythrocytes contain?

A

Haemoglobin

43
Q

What is haemoglobin?

A

Red oxygen carrying pigment of red blood cells

44
Q

What is the structure of haemoglobin?

A

Large globular conjugated protein made up of 4 peptide chains, each with an iron containing haem prosthetic group

45
Q

How many oxygen molecules can haemoglobin bind to?

A

4

46
Q

Haemoglobin + oxygen equation

A

Hb + 4O2 <=> Hb(O2)4
haemoglobin + oxygen <=> oxyhaemoglobin

47
Q

What happens to erythrocytes in capillaries in the lungs?

A

Oxygen level in cells are low, but high in air in alveoli, creating steep concentration gradient
Oxygen loads onto haemoglobin, changing its shape making it easier for the next haemoglobin to bind
Because oxygen is bound, steep diffusion gradient is maintained

48
Q

What is positive cooperativity

A

When oxygen is loaded onto haemoglobin, it changes structure of haemoglobin making it easier for the next oxygen molecule to bind

49
Q

What happens when blood reaches body tissues?

A

Erythrocytes have higher concentration of oxygen so oxygen unloads from haemoglobin and leaves
Once first oxygen molecule unloads, haemoglobin changes shape making it easier for other oxygen molecules to unload

50
Q

What is an oxygen dissociation curve?

A

Graph showing relationship between oxygen and haemoglobin at different partial pressures of oxygen

51
Q

What does high partial pressure mean?

A

Haemoglobin has higher oxygen affinity

52
Q

What effect does CO2 have on haemoglobin

A

Higher Pco2 (left), haemoglobin gives up O2 more easily - Bohr effect

53
Q

Why is Bohr effect importnat

A

In lungs
In active tissues

54
Q

Is foetal haemoglobin curve to left or right?

A

Foetus is dependent on mother for oxygen
Has higher oxygen affinity
Left

55
Q

How is carbon dioxide transported?

A

-Dissolved in plasma
-Combined with amino groups in polypeptide chains of haemoglobin forming carbaminohaemoglobin
-Converted into HCO3 - ions

56
Q

How is carbon dioxide converted to hydrogen carbonate ions?

A

CO2 reacts slowly with water to produced H2CO3 - (carbonic acid) which then dissociates to form…

CO2 + H2O <=> H2CO3 <=> H+ + HCO3-

57
Q

What enzyme catalyses reaction between CO2 and H2O?

A

carbonic anhydrase

58
Q

What is the chloride shift?

A

HCO3 - move out of erythrocytes and Cl- ions move in to maintain electrical balance of cell

59
Q

What is the benefit of carrying CO2 and HCO3 ions

A

Maintains steep concentration gradient for diffusion of CO2

60
Q

What role does haemoglobin play in transport of carbon dioxide?

A

Acts as pH buffer by accepting free H+ ions in reversible reaction to form haemoglobinic acid

61
Q

What catalyses the reverse reaction of CO2+H2O

A

carbonic anhydrase

62
Q

What is the heart

A

Organ that moves blood around the body

63
Q

How does blood move around the heart?

A

-Deoxygenated blood from head and upper body passes through superior vena cava and from lower body through inferior vena cava into right atrium at LP into the atrium
-Atria have thin muscular walls
-Slight pressure build up until AV valve opens, letting blood flow into right ventricle
-When both atrium and ventricle are filled, right ventricle contracts, closing AV valve, blood pumped through semilunar valves into pulmonary artery
-Deoxygenated blood transported to capillary network surrounding lungs
At the same time
-Oxygenated blood from lungs passes through pulmonary veins at HP into left atrium
-Pressure in atrium increases causing AV valve to open allowing blood to pass into left ventricle
-Both left atrium and ventricle fill with blood and then atrium contract forcing all blood into left ventricle
-Left ventricle contracts, forcing blood out of semilunar valve and into aorta

64
Q

What muscle is the heart made of?

A

Cardiac muscle

65
Q

What is the key feature of heart muscle?

A

Myogenic - has its own intrinsic rhythm

66
Q

What supplies the cardiac muscle?

A

Coronary artery

67
Q

What is the heart surrounded by?

A

Inelastic pericardial membrane: prevents heart from over-distending with blood

68
Q

Which side is muscular wall thicker?

A

Left as it requires more force to pump blood to rest of body than to lungs

69
Q

What is the dividing wall in the blood called?

A

Septum - prevents oxygenated and deoxygenated blood mixing

70
Q

What is the cardiac cycle?

A

Describes events in a single heartbeat (0.8s)

71
Q

What is a diastole?

A

Heart relaxes
Atria and ventricles fill with blood
Volume and pressure increases

72
Q

What is a systole?

A

Atria contracts (atrial systole) then ventricles contract (ventricular systole)
Pressure in increases dramatically
Blood forced out of lungs

72
Q

What are the heart sounds

A

Lub- AV valves
Dub- semilunar valves

73
Q

Describe electrical excitation of heart

A

-Wave of electrical excitation begins in SAN, causing atria to contract, initiating heartbeat
-Picked up by AVN which imposes slight delay before stimulating bundle of His made up of Purkyne fibres
-Bundle of His splits up into two branches and conducts wave of excitation to apex of heart
-Triggers contraction of ventricles starting at apex

74
Q

What is an electrocardiogram ECG

A

Recording of electrical heart activity

75
Q

What is tachycardia

A

Heartbeat is rapid

76
Q

What is bradycardia

A

Heart beat is very slow

77
Q

What is ectopic heartbeat

A

Extra heartbeats, out of normal rhythm

78
Q

What is atrial fibrillation

A

Example of arrhythmia, abnormal rhythm of heart

biology (13 decks)

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