myoglobin and haemoglobin

Question 1

describe the components of blood

Answer 1

• non-cellular / cellular components
• plasma: 55%, liquid, matrix in which BC and other components are suspended (proteins, ions, metabolites, wastes, hormones), albumins (protein, bind substances, majority, osmotic pressure), globulins (antibodies, buffer), fibrinogen (clotting, produce fibres)
• platlets: fragments of bone marrow
• WBC: immunity
• RBC: 45% haemoglobin, biconcave, lack nucleus

Question 2

what is the circulatory system

Answer 2

• closed system
• circulates in vessels from and back to a pump (heart)
• transportation (respiratory, nutritive, excretory)
• regulation (hormone transpot, temperature)
• protection (blood clotting, immune defence)

Question 3

what is the respiratory system

Answer 3

• ventilation, air brought to alveoli through system of branches
• site of gas exchange = alveoli

Question 4

how do we get oxygen from air to cells

Answer 4

• hypothetical: oxygen delivered in solution in blood, 2L of oxygen per min from lungs to tissues (4.5mL of oxygen can dissolve in 1 L of blood)
• actual: haemoglobin (respiratory pigment), binds oxygen to protein (not dissolved, 1.25L of oxygen per min

Question 5

what is haemoglobin and what does it transport

Answer 5

• 4 peptide chains
• organic heme group (cofactor)
• iron at centre of each heme group
• O2 binds to each irons (4x), binding to 1st spot causes conformational shift to next group, oxygen bind with more affinity, cooperativity / alesteric interaction
• when O2 binds CO2 is released (haldane effect)
• oxyhaemoglobin / deoxyhaemoglobin

Question 6

what is the oxygen dissociation curve

Answer 6

• relationship between partial pressure of oxygen and saturation of haemoglobin
• sigmoidal curve (characteristic binding)
• pattern of oxygen loading / unloading
• plateau: increasing PO2 = small yield in terms of saturation, diminishing marginal utility, saturation = 90-100%, no free sites (lungs)
• steep curve: haemoglobin affinity for O2 increases as successive molecules bind (tissues - unloading of O2)
• P50: half way saturation, conventional measure
• shift: curve is not stationary shifts left to right dependent on where it is in the body
• left shift: more affinity, high pH, low temp, low partial pressure of CO2 (foetus)
• right shift: low pH, high temp, high partial pressure of CO2 (exercise)

Question 7

how is carbon dioxide transported

Answer 7

• produced by metabolism / cellular respiration
• move through blood as 7% plasma, 23% bound to haemoglobin and 70% transported as HCO3-
• HCO3- = CO2 diffuses into RBC, dissociates into bicarbonate, this diffuses from cell to plasma and reverse occurs there
• CO2 + H2O - H2CO3 - HCO3- + H+

Question 8

describe the importance of blood proteins

Answer 8

hypoproteinemia:
- deficiency of plasma protein (arms and legs are emaciated, skin is tight from edema)
- water leaving body into abdomen, not enough protein in diet, lose muscle, lack of albumin (no osmotic pressure balance), dilute blood (high water, moves into tissues)

Question 9

what is myoglobin

Answer 9

• secondary respiratory pigment
• protein-iron pigment (muscle cells), like haemoglobin, reversibly binds with O2
• temporarily stores O2 and reduces need for continuous blood supply during contraction
• important as blood flow may decrease during muscle contraction

Question 10

what are slow and fast twitch fibres

Answer 10

• slow: red, long contractions without fatigue, lots of myoglobin and mitochondria (high respiratory capacity), rapidly generate ATP
• fast: white, more susceptible to fatigue, poor blood supply, fewer myoglobin / mitochondria
• eye muscles: white (contract 10x faster) than red (maintain posture)
• athletes: endurance have more slow twitch, change in fibre types
• mixture: most muscles are a mix, nurture (proportion of fibre can change) vs nature (proportion initially genetically programmed)