MAB 2

Question 1

How is carbon dioxide carried in the blood?

Answer 1

70% is carried as hydrogen carbonate ions
23% combines with haemoglobin to form carbaminohaemoglobin
7% dissolves into the blood plasma

Question 2

Why is it important that carbon dioxide is removed?

Answer 2

CO2 is produced as a waste product of respiration in bod cells. It reacts with water in the cytoplasm to form carbonic acid. A build up of carbonic acid leads to a decrease in pH, which causes enzymes to denature, which decreases metabolic activity. it also decreases oxygen saturation of haemoglobin.

Question 3

How is oxygen carried in the blood?

Answer 3

Most is transported as oxyhaemoglobin. A small amount is dissolved in the plasma.

Question 4

How is water carried in blood?

Answer 4

Water is carried as blood plasma, which is 90% water.

Question 5

How are salts carried in blood?

Answer 5

Salts are carried as ions dissolved in plasma (referred to as electrolytes).

Question 6

How are lipids carried in blood?

Answer 6

Lipids are absorbed from the digestive system into the lymph as glycerol and fatty acids suspended in plasma. They are mostly transported in the blood as glycerides, phospholipids and cholesterol that are associated with plasma proteins.

Question 7

How are nitrogenous wastes carried in the blood?

Answer 7

Wastes are mostly carried as urea, with a small amount of ammonia and uric acid in the blood plasma.

Question 8

How are other products of digestion carried in blood?

Answer 8

Amnino acids, sugars, vitamins and minerals are dissolved or suspended in plasma.

Question 9

You performed a first hand investigation to demonstrate the effect of dissolved carbon dioxide on the pH of water. Outline the method

Answer 9

1. 10 drops of universal indicator was added to 50ml of water in a beaker
2. A straw was to exhale air through the water, noting that exhaled contains a high proportion of carbon dioxide.
3. Changes in colour were observed and the pH of the water was estimated by comparing the colour against the standard colours shown on the universal indicator pH chart.

Question 10

What is haemoglobin?

Answer 10

Haemoglobin is a protein made up of four polypeptide chains and each is bonded to a haem (iron-containing group).

Question 11

What are some adaptive advantages of haemoglobin?

Answer 11

• Haemoglobin is able to increase the oxygen carrying capacity of blood to gour oxygen molecules per haemoglobin mollecule
• Has an affinity to oxygen, meaning that its ability to bind to oxygen increases once the first oxygen molecule binds to it. This increases the rate and efficiency of oxygen uptake.
• In body tissues, once haemoglobin has released oxygen, it has an increased ability to pick up carbon dioxide. In the lungs, as haemoglobin binds to oxygen, the haemogloin releases carbon dioxide more easily.
• Its ability to release oxygen increases when carbon dioxide is present. Metabolising cells release CO2, and this can react with water in cytoplasm to form carbonic acid. This can lower the pH of the blood. Haemoglobin has the advantage to reduce affinity for oxygen at a lower pH, and so it can release the oxygen in these tissues where it is needed.
• Haemoglobin is enclosed in a red blood cell and therefore does not affect the osmotic balance of the blood

Question 12

Explain the adaptive advantage of haemoglobin in terms of it being pH sensitive.

Answer 12

Haemoglobin is able to release oxygen when carbon dioxide is present. Metabolising cells release CO2, and this can react with water in cytoplasm to form carbonic acid. This can lower the pH of the blood. Haemoglobin has the advantage to reduce affinity for oxygen at a lower pH, and so it can release the oxygen in these tissues where it is needed.

Question 13

What are two examples of technologies used to measure oxygen saturation and carbon dioxide concentrations in blood, and how do they work?

Answer 13

Pulse Oximeter

• can be used to monitor oxygen saturation.
• it is a device that is attaches to earlobe/ fingertip and uses the absorption of light to measure oxygen saturation.
• advantage: it has the ability to be non-invasive and can provide continuous monitoring for patients undergoing anaesthesia or mechanical ventilation
• used during operations requiring general anaesthetic, or on patients in intensive care that require continuous monitoring
• limitations: inaccurate if patient is vasconstricted (may be due to being too cold, or low blood pressure)

Arterial blood gas analysis

• measures oxygen and carbon dioxide level in blood, blood pH and bicarbonate content
• arterial blood is collected and a blood test using computer-based technology analyses the chemical components in the blood. it is an invasive method.
• the analysis evaluates how effectively the lungs are delivering oxygen and how well they are getting rid of CO2.
• used if abnormalities show up in pulse oximeter readings, or severe cases of breathing disturbance
• limitations: may be difficult to perform on patients who are uncooperative or when pulses cannot be easily identified. Challenges arise when patient is unable to be positioned properly for the procedure.

Question 14

What are some structural features of arteries, and what are their functions?

Answer 14

Arteries have thick elastic fibres that enable them to expand to accomodate the increased volume of blood pumped within each heartbeat. When the heart relaxes, the elastic fibres allow the arteries to recoil, squeezing the blood forward and ensuring a continuous flow in one direction.

Arteries also have thick layers of smooth muscle that allows them to withstand the increases in pressure as blood is pumped from the heart. The smooth muscle also functions to adjust the lumen and therefore regulates blood flow in the arteries.

Question 15

What are some structural features of veins, and what are their functions?

Answer 15

Veins have valves, which are small pocket-like folds of the endothelium lining the lumen. They occur at regular intervals along the inside walls of the veins to prevent backflow.

Veins are situated between large groups of muscles and have relatively thin walls. When the musles in the surrounding tissue contract, the relatively thin walls allows the vein to be compressed and thsi propels the blood towards the heart.

Question 16

What are some structural features of capillaries, and what are their functions?

Answer 16

Capillaries have extremely thin walls that are one cell thick. This allows for efficient diffusion of substances.

Capillaries have a small lumen that force red blood cells to pass through in single file, slowing their flow and increasing their exposed surface area for gaseous exchange.

These features maximises exchange of substances between the blood and cells of the body.

Question 17

Distinguish between the terms oxygenated and deoxygenated blood and identiy in which blood vessels in the body one would expect to find the mostly highly oxygenated blood and why.

Answer 17

Oxygenated blood is blood that has oxygen. The oxyhaemoglobin is what gives it its bright red colour. In contrast, deoxygenated blood is blood that has had most of its oxygen removed and is ready to be oxygenated. It is dark/dull red due to the absence of oxyhaemoglobin. The pulmonary vein carries oxygen-rich blood from the lungs to the heart, so this is where the most highly oxygenated blood would be found.

Question 18

Compare arteries, capillaries and veins in therms of the structure of their walls, the size of the lumen and the direction of flow.

Answer 18

The walls of arteries are very thick and muscular to withstand the high pressure of blood being pumped out of the heart. Blood that passes through the veins flow at a lower pressure, and so their walls are thinner than arteries. Capillaries have extremely thin walls that are only one cell thick to facilitate the dffusion of substances in and out of cells. The size of the lumen is proportional to the wall size. Arteries have thicker walls in proportion to their lumen, and since the walls of veins are thinner, their lumens are correspondinly larger in diamter than arteries to allow easy flow of blood. Capillaires have the thinnest walls, and their lumens are correspondingly larger in diamter, however is smaller than the lumsn of arteries and veins. Arteries carry blood away from the heart, veins carry blood back to the heart, and capillaries facilitates diffusion in and out of cells.

Question 19

Outline a method that would be used to estinate the size of red and white blood cells.

Answer 19

1. View ruler under low power (LP) to estimate diameter of field of view. Calculate diameter for high power (HP) by dividing magnification of LP by the magnification of HP. Then times this result by diameter of LP field of view.
2. View prepared slide of blood under LP, then HP.
3. Estimate/count number of red blood cells across diameter of the field of view.
4. Estimate the size of red blood cells by dividing the diameter by number of red blood cells counted.
5. Draw scaled diagram of red blood cells
6. Repeat steps 2-5 but with white blood cells. Compare.

Question 20

What is the chemical composition of blood in the lungs?

Answer 20

increase in oxygen, decrease in carbon dioxide

Question 21

What is the chemical composition of blood in organs other than the lung?

Answer 21

decrease in oxygen, increase in carbon dioxide

Question 22

What is the chemical composition of blood in in organs involved in absorbing digested foods e.g. small intestine?

Answer 22

increase in digestive end products e.g. glucose, fatty acids, amino acids

Question 23

What is the chemical composition of blood in the liver?

Answer 23

decrease in digestive end products e.g. glucose, fatty acids, amino acids

increase in nitrogenous wastes

Question 24

What is the chemical composition of blood in the kidneys?

Answer 24

decrease in nitrogenous wastes, kidneys filter and excrete them

Question 25

Why do living cells need oxygen?

Answer 25

Oxygen is essential for cellular respiration, a process by which cells obtain energy from glucose. Energy is needed for growth, repair, movement, excretion and reproduction.

Question 26

What are some products of donated blood and what are their uses?

Answer 26

Red blood cells: provides oxygen, given to people who are anemic or do not produce enough red blood cells Platelets: contain blood clotting factors Plasma: volume expanders, also contain blood clotting factor VIII- given to patients who have haemophilia and are bleeding due to an accident

Question 27

Outline the advantage of the use of blood products as opposed to whole blood

Answer 27

Blood products can treat the particular need of each patient by transfusing only the specific required blood product, therefore blood can be used more effectively. The use of blood products rather than whole blood has tripled the number of transfusions that can be given for each unit of blood donated.

Question 28

Outline reasons why research into the production of artificial blood important

Answer 28

There are not enough blood donors to cater for the number of people requiring blood transfusions. Some countries do not even have blood donor facilities. Military purposes: to help injured soldiers' artifical blood can save many lives No substitutes have been developed as of yet to carry out immune defence or clotting of blood. These are areas of future research. There is a lack of donated blood so the it is imperative that further research is conducted to perfect the formulation of artifical blood

Question 29

Identify the most important features that are expected in an artificial blood substitute.

Answer 29

- long storage life - can be produced in large quantities cheaply - free of infectious agents - does not trigger an immune response - does not have to be cross matched for different blood types

Question 30

What are some advantages of artifical blood?

Answer 30

- can be sterilised - no cross matching needed - long storage life - no risk of infection

Question 31

Describe some proposed replacements for blood: perfluorocarbons

Answer 31

Perfluorocarbons (PFCS) are artificial oxygen carriers. They carry oxygen in a dissolved form, and can carry up to 50 times more dissolved oxygen than plasma. They are relatively cheap to produce, however they are insoluble in blood and must be combined with lipids in order to mix with the bloodstream. The lipid tested was approved the Food and Drug administration in the United States of America, but has not been successful because it cannot be given in large enough quantities to produce a significant results. Future research includes improved versions of perfluorocarbon emulsions for easier combination with blood.

Question 32

Describe some proposed replacements for blood: haemoglobin-based oxygen carriers

Answer 32

The use of HBOCs involve extracting haemoglobin from outdated human blood and modifying it to a form where it can be used in artificial blood. A limitation of HBOCS is that it has a greater affinity for oxygen than haemoglobin, so it does not release oxygen as readily in tissues where it is needed. It also has a short circulation time, as they are not protected by a membrane. Current research for the development and use of HBOCs as artificial blood involves the cross-linking of the haemoglobin to enzymes found naturally in blood, to create a more stable 'second generation' HBOC that will not break down. Future research involves enclosing the haemoglobin, with the required enzymes inside an artifical cell membrane (lipid vessel) to increase the circulation time.

Question 33

Draw transverse and longitudinal sections of phloem and xylem tissue

Answer 33

rip cant add images here

Question 34

Why must nitrogenous waste be excreted?

Answer 34

Nitrogenous wastes tend to form ammonia, which raises the pH of body fluids. A change in pH will cause enzymes to denature which decreases metabolic activity.

Question 35

Describe a current theory about the movement of materials through plants in xylem tissue

Answer 35

Transpiration stream theory: The transpiration stream in xylem occurs due to the physical forces that result in water and ions being moved by passive transport. A column of water is sucked up the stem by the evaporative pull of the transpiration stream. Evidence: This theory is supported by the fact that xylem vessels are hollow and narrow, offering very little resistance to the flow of water. Also, the physical properties of water contribute to the formation of a continuous stream. - Cohesion: bond between water molecules - Adhesion: bond between water and side of walls The combination of adhesive and cohesive forces, together with the suction pull of transpiration create the transpiration stream.

Question 36

Describe a current theory about the movement of materials through plants in phloem tissue

Answer 36

Pressure-flow theory: 3 main stages- 1 ) Movement of sugars from the source (leaves) into the phloem, usually against a concentration gradient, thus active transport is needed. 2) Movement in the phloem due to pressures from the source and hydrostatic pressure. 3) Unloading from the phloem to the sink (cells that need it), again needing active transport, expending cellular energy. The difference in osmotic pressure between the source and the sink is what drives the phloem sap to flow.

Question 37

What does xylem consist of?

Answer 37

Long tubes of dead cells consisting of: - xylem vessels - tracheids - fibres - parenchyma cells

Question 38

What does phloem consist of?

Answer 38

Tubes of living cells consisting of: - phloem fibres - companion cells - sieve cells - phloem parenchyma

Question 39

Explan why the presence of haemoglobin in the red blood cells of mammals is an adaptive advantage.

Answer 39

Oxygen can combine with haemoglobin to form oxyhaemoglobin. This increases the oxygen-carrying capacity of the blood. Mammals are endotherms and thus use heat from internal metabolic processes to maintain body temperature, for example oxygen is used in respiration to release energy in the form of ATP and heat. It is therefore an adaptive advantage for mammals to have haemoglobin in their red blood cells to carry more oxygen to release more energy to maintain body temperature and ensure optimum conditions for chemical reactions.

Question 40

Explain why is is incorrect to say that arteris carry oxygenated blood and veins carry deoxygenated blood.

Answer 40

The human circulatory system is a double system with the right side of teh heart pumping blood to the lungs and the left side of the heart pumping to the body. While most arteries carry oxygenated blood and most veins carry deoxygenated blood, it is the pulmonary artery that carries deoxygenated blood to the lungs from the heart, and the pulmonary vein carries the oxygenated blood to the heart.

Question 41

Compare the transport of water in plants with the transport of water in animals.

Answer 41

In plants, mineral ions are dissolved in water and are transported up the plant, while in animals, mineral ions and vitamins are transported in the plasma of blood. In plants, water is transported via the xylem while in animals, water is transported via veins, arteries and capillaries. The mechanism for transport in plants is the transpiration stream, where cohesion and adhesion draws water up the xylem. In comparison, animals have a heart that pumps blood around the body.