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Mass Transport(unedited) Flashcards

1
Q

What is haemoglobin (Hb) role?

A

-Human haemoglobin is found in red blood cells
-role is to carry oxygen around the body in form of oxyhaemoglobin

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2
Q

What is haemoglobin?

A

-a large protein with a quaternary structure
-made up of four polypeptide chains
-each chain has a haem group which contains an iron ion(red colour)
-Each molecule of haemoglobin can carry four oxygen molecules.

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3
Q

What is it called when an oxygen molecule binds / unbinds to haemoglobin?

A

-association and loading
-dissociation and unloading

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4
Q

What is affinity for oxygen?

A
  • tendency that a molecule to bind with oxygen
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5
Q

what affects haemoglobin’s affinity for oxygen?

A

-partial pressure of oxygen (pO2) which is a measure of oxygen concentration.
-As pO2 increases, haemoglobin’s affinity for oxygen also increases

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6
Q

Why does oxygen load onto haemoglobin in the alveoli?

A

-Oxygen enters blood capillaries at the alveoli in the lungs
-Alveoli have a high pO2 so oxygen loads onto haemoglobin to form oxyhaemoglobin

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7
Q

What happens when cells respire?

A

-they use up oxygen- this lowers the pO2
-RBC’s deliver oxyhaemoglobin to respiring tissues, where it unloads its oxygen

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8
Q

How are erythrocytes (RBC) adapted to transport oxygen?

A

-biconcave shape for large SA:V allowing oxygen to diffuse rapidly
-alot of haemoglobin (oxygen carrying protein)
-lost nucleus for more space for haemoglobin

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9
Q

What does the oxygen dissociation curve show?

A

-shows how saturated the haemoglobin is when oxygen at any given partial pressure.
-y-axsis (% saturation of Hb with oxygen) x-axsis (partial pressure of oxygen kPa)

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10
Q

Why does the “Dissociation Curve” have an s shape

A

-sigmoid curve
-at low pO2 Hb has a low affinity to oxygen
-once the first oxygen molecule is bound its easier for other molecules
-last oxygen molecule needs a high pO2 to bind as 3/4 haem groups have already binded

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11
Q

What happens when one molecule of oxygen binds to haemoglobin?

A

-quaternary structure of the Hb molecule changes increasing affinity
-this is called positive cooperativity

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12
Q

What is the Bohr effect?

A

-cells respire they produce carbon dioxide, raising the pCO2.
-blood with oxygen is lower for a high pCO2
-This increases the rate of oxygen unloading- so the dissociation curve ‘shifts’ right

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13
Q

How does low oxygen environment affect animals haemoglobin?

A

-they have haemoglobin with a higher affinity for oxygen
-isnt much oxygen so haemoglobin has to be very good at loading any oxygen

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14
Q

How does high activity levels affect animals haemoglobin?

A

-High activity levels
-haemoglobin with a lower affinity for oxygen
-to deliver oxygen to respiring cells

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15
Q

How does an animals size affect their haemoglobin?

A

-small animals lose more heat so they have a high metabolic rate to compensate
-small mammals haemoglobin with a lower affinity for oxygen
-Hb has to easily unload to meet the high oxygen demand

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16
Q

What is the heart?

A

-muscular organ that lies in the thoracic cavity
-pumps blood around your body, through your blood vessels.

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17
Q

Whats the structure of the left ventricle for its function?

A

-thicker muscular walls
-contract powerfully and pump (oxygenated) blood all the way around the body.

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18
Q

What are the functions of pocket valves?

A

-in veins
-ensure that when the veins are squeezed, blood flows back towards the heart rather than away from it

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19
Q

What side of the heart transports de/oxygenated blood?

A

-right side pumps deoxygenated blood to the lungs
-left side pumps oxygenated blood to the whole body

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20
Q

What do the atrioventricular (AV)and semi-lunar (SL) valves do?

A

-AV links the atria to the ventricles
-SL links the ventricles to the pulmonary artery and aorta
- UNIDIRECTIONAL BLOOD FLOW

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21
Q

What do the cords/valve tendons do?

A

-attach the atrioventricular valves to the ventricles
-stops valves being forced up into the atria when the ventricles contract (backflow)

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22
Q

What does the vena cava do ?

A

-superior vena cava delivers blood from the head and chest area to the heart
-inferior vena cava returns blood from the lower body regions to the heart

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23
Q

What happens at ventricular systole stage of the cardiac cycle?

A

-ventricles contract
-volume decrease ,pressure increase
-semi-lunar valves open
-forces blood out through the pulmonary arteries and aorta

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24
Q

What happens at atrial systole stage of the cardiac cycle?

A

-atria contracts
-atroventricular valves open
-blood ejected into the ventricles

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25
Whats the Circulatory system?
- mass transport system -carries raw materials, waste products around the body
26
Why do multicellular organisms, like mammals need a circulatory system?
-low surface area to volume ratio - specialised mass transport system to carry raw materials from specialised exchange organs to their body cells
27
What is the circulatory system is made up of?
-heart -Blood vessels: -arteries -arterioles -veins -capillaries
28
What carries blood from heart to the lungs?
-Pulmonary artery
29
What carries blood from the lungs to the heart?
-Pulmonary vein
30
What carries blood from the heart to the body?
-Aorta
31
What carries blood from the body to the heart?
-Vena cava
32
What carries blood from the body to the Kidneys?
-Renal artery
33
What carries blood from the Kidneys to the Vena Cava?
-Renal vein
34
What do Arteries do ?
-carry blood away from the heart and to the rest of the body -carry oxygenated blood except for the pulmonary arteries (deoxygenated blood to the lungs)
35
What are Arteries structure?
-thick and muscular walls -elastic tissue (helps them recoil as the heart beats, and maintain the high pressure) -endothelium /inner lining is folded (allows artery to stretch which maintain high pressure)
36
What are Arterioles and what do they do?
-arteries divide into smaller vessels -form a network throughout the body -muscles inside the arterioles contract to restrict the blood flow or relax to allow full blood flow.(to meet demands of blood)
37
What do Veins do ?
- take blood back to the heart under low pressure -carry deoxygenated blood apart from pulmonary veins (oxygenated blood from lungs to heart)
38
What are the structures of veins?
-wider lumen -very little elastic or muscle tissue (due to low pressure) -pocket valves (prevent backflow of blood) -Blood flow is helped by the contraction of the body muscles surrounding them
39
What do Capillaries do?
-Arterioles branch into capillaries -smallest of the blood vessels -adapted for efficient diffusion. -form networks (capillary beds)
40
What are Capillary structure?
-found close to cells in exchange tissues (e.g. alveoli), so there’s a short diffusion pathway -walls are only one cell thick, short diffusion pathway -large number of capillaries, increase surface area
41
Whats in the blood?
Cells: -Red blood cells -White blood cells -Platelets Plasma: -Glucose -Amino acids -Mineral ions -Oxygen -Plasma proteins (albumin)
42
What is tissue fluid?
-fluid that passes out of blood and bathes the tissue cells
43
How does tissue fluid move in and out of the capillaries?
-forced out of the blood at the arterial end of the capillaries - transfers molecules like oxygen and glucose to tissue cells -waste is transferred to the fluid -returns back to the blood at the venous end of the capillaries
44
What are the competing factors for movement of tissue fluid?
-hydrostatic pressure -oncotic pressure
45
How do substances move in and out of the capillaries, into the tissue fluid?
-pressure filtration -tissue doesn’t contain RBCs or big proteins, too large to be pushed out the capillary walls -Cells take in oxygen and nutrients from the tissue fluid, and release metabolic waste into it.
46
What pressure is high and why at the arterial end?
-hydrostatic pressure -blood has just passed through an artery to an arteriole so still under high pressure -pushes fluid out of blood to tissue
47
How can water move back into the blood by osmosis?
-Plasma proteins = hydrophillic -they lower water potential in the blood plasma -so water can move back into the blood by osmosis
48
What pressure is high and why at the venous end?
-Oncotic pressure is high -plasma proteins in the blood plasma
49
What is ultrafiltration?
-tissue fluid being forced out of the capillary through the gaps in the endothelial cells
50
What happens to the remaining 10% of water not absorbed in tissue fluid?
-drains into a series of blind-ended vessels called lymph capillaries
51
Why is the water potential at the venule end of the capillary bed lower than the water potential in the tissue fluid?
-the fluid loss -increasing concentration of plasma proteins(don’t leave the capillaries) -SO some water re-enters the capillaries from the tissue fluid at the venule end by osmosis.
52
What is a Cardiovascular disease?
-describe diseases associated with the heart and blood vessels -Most start with atheroma formation
53
What is Coronary heart disease and when does it occur?
-cardiovascular disease -coronary arteries have lots of atheromas which restricts blood flow to the heart muscle -lead to myocardial infarction
54
How do Atheromas form?
-damage occurs in endothelium (inner lining) by e.g, high BP -WBCs and lipids from blood, clump together under the lining forming fatty streaks -more WBC and lipids build up and harden forming fibrous plaque (atheroma) -causes blockages in lumen of artery increasing BP
55
What is an Aneurysm and how does it form?
-balloon-like swelling of the artery -starts with formation of atheromas which damage and weaken arteries
56
What is Thrombosis?
-formation of a blood clot -clot can cause complete blockage of the artery
57
What is Myocardial infarction?
-coronary artery becomes completely blocked and an area of the heart receives no oxygen
58
How is smoking a risk factor for Cardiovascular disease?
-carbon monoxide and nicotine -Carbon monoxide binds haemoglobin and reduces the amount of oxygen transported to tissues in blood -decreases the amount of antioxidants so damage in the coronary artery walls is more likely
59
What happens at diastole stage of the cardiac cycle?
-relaxation of the heart -atria begin to fill with blood
60
What does xylem tissue transport?
-water and mineral ions in solution -from the roots to the leaves
61
What is the structure of the xylem?
-long, tube-like structures formed from dead cells -no cytoplasm to for empty tube -no end walls cells, making an uninterrupted tube - rigid because of lignin in their thick side wall (withstand high water pressure)
62
What is the cohesion-tension theory?
-water is polar therefore cohesive -Water evaporates from leaves at the ‘top’ of the xylem (transpiration) - creates tension (suction) pulling more water up -others water molecules follow forming column of water in the xylem due to cohesion -water enters stem through the roots (transpiration pull) forming a continuous water column.
63
What is the evidence for cohesion-tension theory?
-Change in the diameter of tree trunks according to the rate of transpiration -xylem vessel is broken and air enters it -xylem vessel is broken, water does not leak out
64
What is the transpiration stream?
-passive process -stomata are open, plants lose water vapour -Water evaporates from the moist cell walls and accumulates in the spaces between cells in the leaf -exits the leaf through the stomata down the water potential gradient - loss of water is transpiration
65
Factors affecting transpiration rate:
-Light intensity -Wind -Humidity -Temperature
66
What does a Potometer do?
-estimates transpiration rate
67
What does the Phloem transport?
-dissolved substances/assimilates (mainly sugars like sucrose) from source to sink
68
What is the structure of the phloem?
-cells arranged in tubes(like phloem) -Sieve tube elements are living cells that form the tube for transporting solutes (no nucleus ,few organelles ) -companion cell for each sieve tube element (provide energy to seive tube ) -porous to allow liquids and sucrose to flow through
69
What is Translocation?
-energy requiring process that takes place in the phloem. -movement of solutes (e.g. amino acids and sugars like sucrose) to where they’re required in the plant -Enzymes maintain a concentration gradient from the source to the sink by changing the solutes at the sink
70
What is the Mass flow theory?
1)transfer of sucrose into the sieve tube elements from the palisade cells (photosynthesising tissue via active transport to load the solutes and facilitated diffusion from the palisade cells into companion cells 2)Mass flow of sucrose through the sieve tube elements as water potential in sieve tubes is low soo water enters via osmosis from xylem and companion cells ccreating high hydrostatic pressure 3)Sucrose moves into the sink cells by facilitated diffusion down conc. gradient forming low water potential inside the sink cells so water to move into the respiring cells from the sieve cells via osmosis
71
What is evidence for mass flow theory?
-Ringing experiments (ring of bark including phloem not xylem is removed from a woody stem, a bulge forms above the ring in high conc of sucrose) -Radioactive tracer(carbon (C14) can be used to track the movement of organic substances) -Aphid experiments (evidence that there’s a pressure gradient)

Biology (13 decks)

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