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Biology OCR A A level > Transport in Animals > Flashcards

Transport in Animals Flashcards

1
Q

Give 5 reasons why specialist transport systems are needed

A

1) Metabolic demands of multicellular organisms are high
2) SA:V gets smaller as multicellular organisms get bigger
3) Hormones and enzymes need to be transported around the body
4) Food digested needs to be transported
5) Waste products of metabolism needs to be removed from cells and transported to excretory organisms

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2
Q

What are 3 key features of a circulatory system?

A

A liquid transport medium
Vessels
Pumping mechanism

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3
Q

What is a mass transport system?

A

Substances being transported in a mass of fluid with a mechanical mechanism for moving the fluid

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4
Q

What is an open body cavity called?

A

Haemocoel

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5
Q

Explain movement of transport medium in an open circulatory system

A

Transport medium pumped straight from heart into haemocoel
Transport medium under low pressure and comes into direct contact with cells
Exchange occurs
Transport medium returns to heart via open ended vessel

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6
Q

Where are open ended circulatory systems found?

A

Invertebrate animals

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7
Q

What is insect blood called?

A

Haemolymph

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8
Q

What does haemolymph carry and not carry?

A

Carries food, nitrogenous waste and cells involved with defence against disease

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9
Q

Explain the movement of blood in a closed circulatory system

A

Heart pumps blood around the body under pressure and quickly
Blood returns directly to heart
Substances leave and enter blood by diffusion through walls of blood vessels

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10
Q

What is a single circulatory system?

A

Blood travels through heart once for each complete circulation of the body

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11
Q

What does blood pass through before returning to heart in single closed circulatory system? What is the effect of this?

A

2 sets of capillaries, 1st exchanges O2 and CO2, 2nd different substances
Result of this= blood pressure drops significantly and so returns to heart slowly

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12
Q

What is a double circulatory system?

A

Blood pumps through heart twice for each complete circulation of the body

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13
Q

What are the 2 separate circulations of blood in a double system?

A

Blood from heart to lungs to pick up O2 and offload CO2, returns to heart
Heart to body

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14
Q

What do elastic fibres contain and do?

A

Composed of elastin

Stretch and recoil, providing vessel walls with flexibility

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15
Q

What does smooth muscle do?

A

Contracts or relaxes affecting size of lumen

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16
Q

What does collagen do?

A

Provides structural support to maintain shape and volume of the vessel

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17
Q

What do arteries carry? Give the 2 exceptions

A

Oxygenated blood away from the heart

Except: pulmonary artery (heart to lungs) and umbilical artery(foetus-placenta) which carries deoxygenated blood

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18
Q

What is the role of elastic fibres within the heart?

A

Withstand force of heart
Stretch to take larger volume
Recoil between contractions

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19
Q

Why is it important for arteries to recoil between contractions of heart?

A

To even out surges of blood and give a continuous flow

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20
Q

What do arterioles contain? Why?

A

Smooth muscle, no pulse but need to constrict and dilate to effect flow to organs

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21
Q

How do substances pass in and out of the capillaries?

A

Gaps between endothelial cells

Through capillary walls

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22
Q

Give 3 ways capillaries are adapted for their roles

A

Large surface area for diffusion
Total cross sectional area is smaller than the artery supplying it so flow is decreased, increasing time for exchange
Walls are single endothelial cell thick

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23
Q

What do veins carry? Give 2 exceptions

A

Veins carry deoxygenated blood back towards the heart

Exceptions: pulmonary vein(lungs-heart) and umbilical vein(placenta-foetus) which carry oxygenated blood

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24
Q

What is the structure of a vein?

A

Lots of collagen
Limited elastic fibre
Wide lumen
Smooth thin lining

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25
What are the 3 major adaptions of veins to go against gravity?
One way valves to prevent backflow Run through major muscles so when they contract the blood is forced up too Breathing movements to force blood towards the heart
26
What does plasma contain?
Glucose Amino acids Hormones Plasma Proteins
27
What is the role of albumin?
Maintains osmotic pressure of the blood
28
What is the role of fibrinogen?
Important in blood clotting
29
What is the role of globulins?
Transport and the immune system
30
What are platelets and what is their role?
Fragments of megakaryocytes found in red bone marrow | Involved in blood clotting
31
What 7 things does the blood have to transport?
Oxygen and CO2 to and from cells Digested food from small intestine Nitrogenous waste products from cells to excretory organisms Chemical messages Food molecules from storage compounds Platelets to damaged areas Cells and antibodies involved with the immune response
32
What are the 2 other roles of blood apart from transport?
Maintain steady body temperature | Minimises pH changes
33
How is tissue fluid formed?
Hydrostatic pressure creates a high pressure at arterial end Water and small molecules forced out (not plasma proteins as they're too big) through fenestrations in capillaries as hydrostatic pressure is greater than oncotic pressure Gathers in interstitial space
34
What is oncotic pressure?
Tendency of water to move into the blood by osmosis
35
When does tissue fluid return to the blood? Why?
Venous end of capillaries | Oncotic pressure > hydrostatic pressure so 90% tissue fluid returns
36
What is lymph?
10% of fluid that doesn't return with a high proportion of fatty acids and urea.
37
Where is lymph contained?
System of blind ended tubes called lymph capillaries which join to form larger vessels, returns to blood under subclavian veins
38
What do lymph nodes do?
Intercept bacteria and other debris from lymph
39
Give the equation of oxygen binding reversibly with haemoglobin
Hb +4O2 = Hb(O2)4
40
What is positive cooperativity?
Once one oxygen molecule binds to a haem group it causes a conformational change that makes it easier for next oxygen to bind
41
What does an oxygen dissociation curve plot?
Percentage saturation of haemoglobin against partial pressure of oxygen
42
What is the shape of an oxygen dissociation curve? Why?
Sigmoidal High partial pressures-flattens as all haem groups bound to oxygen Low partial pressures- steep due to positive cooperativity
43
Explain the Bohr Effect
As partial pressure of carbon dioxide rises, haemoglobin gives up oxygen more easily
44
Why is the Bohr Effect important?
Active Tissues with high proportion of haemoglobin, CO2 given up easily Lungs where CO2 concentration is low oxygen binds easily
45
How is fetal haemoglobin adapted?
Has a higher affinity for oxygen than mothers so oxygen passes across the placenta from mother into the fetus
46
What are the 3 ways that carbon dioxide is carried in the blood?
Dissolved in plasma (5%) Carbaminohaemoglobin (20%) Hydrogen carbonate ions (75%)
47
Explain process of carbon dioxide converting to hydrogen carbonate ions
Carbon dioxide +water- carbonic anhydrase- hydrogen ions and hydrogen carbonate ions
48
Which enzyme catalyses the formation of hydrogen carbonate ions?
Carbonic anhydrase
49
Explain the chloride shift
Hydrogen carbonate ions move out of erythrocytes | Negatively charged chloride ions move into erythrocyte to maintain charge balance
50
What happens when the blood reaches the lungs where there is little CO2?
Carbonic anhydrase catalyses reverse reaction Carbon dioxide and water formed Hydrogen carbonate ions move back into erythrocytes and react with H+ ions to form more carbonic acid CO2 diffuses out of lungs Chloride ions move back to plasma
51
How does haemoglobin impact movement of CO2?
Prevents pH changes by absorbing free H+ions to form haemoglobinic acid
52
What is the heart made from?
Cardiac muscle which contracts and relaxes in a regular rhythm
53
What supplies the cardiac muscle with oxygen?
Coronary arteries
54
What is the heart surrounded by? Why?
Inelastic pericardial membranes which prevent the heart from over distending with blood
55
What is the role of the tendinous cords?
To prevent the valves from being turned inside out by pressure exerted when ventricle contracts
56
Explain what happens on the right side of the heart
Blood enters right atrium from vena cava Pressure builds up Atrioventricular valve opens Blood passes into right ventricle Atrium and ventricle filled, atria contracts forcing all blood into ventricle Atrioventricular valve shuts to prevent backflow, ventricle starts to contract Right ventricle contracts forcing blood out of semi lunar valves into pulmonary artery to lungs Semi lunar valves shut
57
Explain what happens on the left side of the heart
``` Blood enters from pulmonary vein Pressure builds in left atrium Bicuspid valve opens Left ventricle fills Left atria contracts Blood forced into ventricle Bicuspid valve shuts Ventricle contracts Forces blood through semilunar valves into aorta ```
58
Why is the left side of the heart thicker?
Has to generate enough force to push blood around the body rather than just to the lungs which has more resistance
59
What is the septum? What is its role?
Inner dividing wall of the heart which prevents mixing of deoxygenated and oxygenated blood
60
What is the cardiac cycle?
The events of a single heartbeat
61
How long does the cardiac cycle last in humans?
0.8 seconds
62
What happens in diastole?
Heart relaxes Atria and ventricles fill with blood Volume and pressure increase Pressure in arteries at minimum
63
What happens in systole?
Atria and ventricles contract | Pressure inside heart increases dramatically
64
Explain the changes in aortic pressure throughout the cardiac cycle
Rises when ventricles contract Gradually falls Recoil action at end of contraction causes small rise
65
Explain changes in atrial pressure throughout the cardiac cycle
Always relatively low Increases when atria contracts Falls when atrioventricular valve shuts and atria relaxes Gradual increase in pressure when ventricles are contracting Falls when atrioventricular valve opens in diastole
66
Explain changes in ventricular pressure during the cardiac cycle
Low to begin Increases as ventricles fill with blood Left atrioventricular valve closes, pressure rises dramatically during contraction Pressures rises above aorta, forcing blood out Pressure falls as ventricles relax
67
Explain change in ventricular volume during the cardiac cycle
Rises as atria contract Falls suddenly when blood forced into aorta Volume increases again during diastole
68
What sound does the heart make?
Lub-dub
69
What does the lub-dub sound signify?
``` Lub= atrioventricular valves shutting as ventricles contract Dub= blackflow closes semilunar valves in aorta and pulmonary artery as ventricles relax ```
70
What does it mean for the cardiac muscle to be 'myogenic'?
Have its own intrinsic rhythm
71
Explain the process of a heartbeat
A wave of excitation begins at sino-atrial node Causes atria to contract Electrical activity picked up by atrioventricular node AVN imposes slight delay Stimulates 'Bundle of His' Wave passed through purkyne fibres which penetrate septum Wave reaches apex of heart Purkyne fibres spread through ventricle and wave causes contraction from apex upwards
72
Why does the AVN impose a slight delay?
To make sure that the atria have stopped contracting before the ventricles start contracting
73
Why does contraction start at the apex?
To allow for more efficient emptying of the ventricles
74
What does an electrocardiodiagram measure?
Electrical activity of the heart by detecting differences in your skin
75
What is tachycardia and when does it occur?
When the heartbeat is very rapid, over 100bpm | Occurs normally during exercise, fever, frightened or angry
76
How is serious tachycardia treated?
Medication or surgery to maintain electrical control of the heart
77
What is bradycardia and when does it occur?
When the heartbeat is very slow, below 60bpm, occurs when extremely fit
78
How is serious bradycardia treated?
Artificial pacemaker
79
What is an ectopic heartbeat?
An extra heartbeat out of the normal rhythm
80
What happens during atrial fibrillation?
Arrhythmia Rapid electrical impulses in atria Contract very fast Heart doesn't pump effectively as ventricle doesn't fill

Biology OCR A A level (17 decks)

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