Flashcards in MAB 2 Deck (41):
How is carbon dioxide carried in the blood?
70% is carried as hydrogen carbonate ions
23% combines with haemoglobin to form carbaminohaemoglobin
7% dissolves into the blood plasma
Why is it important that carbon dioxide is removed?
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.
How is oxygen carried in the blood?
Most is transported as oxyhaemoglobin. A small amount is dissolved in the plasma.
How is water carried in blood?
Water is carried as blood plasma, which is 90% water.
How are salts carried in blood?
Salts are carried as ions dissolved in plasma (referred to as electrolytes).
How are lipids carried in blood?
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.
How are nitrogenous wastes carried in the blood?
Wastes are mostly carried as urea, with a small amount of ammonia and uric acid in the blood plasma.
How are other products of digestion carried in blood?
Amnino acids, sugars, vitamins and minerals are dissolved or suspended in plasma.
You performed a first hand investigation to demonstrate the effect of dissolved carbon dioxide on the pH of water. Outline the method
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.
What is haemoglobin?
Haemoglobin is a protein made up of four polypeptide chains and each is bonded to a haem (iron-containing group).
What are some adaptive advantages of haemoglobin?
- 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
Explain the adaptive advantage of haemoglobin in terms of it being pH sensitive.
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.
What are two examples of technologies used to measure oxygen saturation and carbon dioxide concentrations in blood, and how do they work?
- 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.
What are some structural features of arteries, and what are their functions?
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.
What are some structural features of veins, and what are their functions?
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.
What are some structural features of capillaries, and what are their functions?
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.
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.
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.
Compare arteries, capillaries and veins in therms of the structure of their walls, the size of the lumen and the direction of flow.
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.
Outline a method that would be used to estinate the size of red and white blood cells.
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.
What is the chemical composition of blood in the lungs?
increase in oxygen, decrease in carbon dioxide
What is the chemical composition of blood in organs other than the lung?
decrease in oxygen, increase in carbon dioxide
What is the chemical composition of blood in in organs involved in absorbing digested foods e.g. small intestine?
increase in digestive end products e.g. glucose, fatty acids, amino acids
What is the chemical composition of blood in the liver?
decrease in digestive end products e.g. glucose, fatty acids, amino acids
increase in nitrogenous wastes
What is the chemical composition of blood in the kidneys?
decrease in nitrogenous wastes, kidneys filter and excrete them
Why do living cells need oxygen?
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.
What are some products of donated blood and what are their uses?
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
Outline the advantage of the use of blood products as opposed to whole blood
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.
Outline reasons why research into the production of artificial blood important
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
Identify the most important features that are expected in an artificial blood substitute.
- 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
What are some advantages of artifical blood?
- can be sterilised
- no cross matching needed
- long storage life
- no risk of infection
Describe some proposed replacements for blood: perfluorocarbons
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.
Describe some proposed replacements for blood: haemoglobin-based oxygen carriers
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.
Draw transverse and longitudinal sections of phloem and xylem tissue
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Why must nitrogenous waste be excreted?
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.
Describe a current theory about the movement of materials through plants in xylem tissue
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.
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.
Describe a current theory about the movement of materials through plants in phloem tissue
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.
What does xylem consist of?
Long tubes of dead cells consisting of:
- xylem vessels
- parenchyma cells
What does phloem consist of?
Tubes of living cells consisting of:
- phloem fibres
- companion cells
- sieve cells
- phloem parenchyma
Explan why the presence of haemoglobin in the red blood cells of mammals is an adaptive advantage.
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.
Explain why is is incorrect to say that arteris carry oxygenated blood and veins carry deoxygenated blood.
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.