Term
| cellular elements of blood |
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Definition
| erythrocytes, leukocytes, platelets |
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white blood cells
eg monocytes, lymphocytes |
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| involved in blood clotting |
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blood minus the cells
proteins, nutrients, ions, wastes, hormones |
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Definition
immunoglobins
clotting proteins
lipid escort B |
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8% of body weight
4-6 liters |
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Definition
packed cell volume
the normal value (45%) is regulated; departures from this value are either adaptive or pathological |
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Term
| what does a low value of hematocrit mean? |
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Definition
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Term
| what does a high value of hematocrit mean? |
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Definition
| polycythemia (adaptive or pathological) |
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Term
| what is the origin of cellular elements in blood? |
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Definition
stem cells in bone marrow
- mitotically active
- some of daughter remains stem cells, others differentiate |
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Term
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Definition
composed of four globin chains (two beta two alpha), each with a heme group that can carry a molecule of oxygen
- 250 million hemoglobin in one red blood cell
- 95% of dry weight of the cell |
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Definition
a stretchable protein under the plasma membrane; confers strength to the cell
Allows the red blood cells shape to be distorted in microcirculation without shearing the cell |
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Definition
generate ATP by glycolysis
red blood cells have no mitochondria |
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Term
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Definition
catalyzes the formation of carbonic acid from CO2 and water
CO2 + H2O -> H2CO3
H2CO3 -> H+ + HCO3- |
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Term
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Definition
hemoglobin,
spectrin,
glycolytic enzymes,
carbonic anhydrase,
no nucleus, organelles or ribosomes
(more room for hemoglobin but shorter life) |
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Definition
formation of erythrocytes
process takes four days from stem cell to erythrocyte
begins in bone marrow
is completed in circulating blood
Rate: 100 million cells per minute
normally balanced with erythrocyte destruction |
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Term
| destruction of erythrocytes |
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Definition
they break apart in capillaries due to mechanical stress within 3-4 month of their formation
the debris is eaten by macrophages in the spleen and liver |
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Term
| Why is hemoglobin needed to carry oxygen in the blood? |
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Definition
O2 alone has low solubility in blood
heme alone would carry CO not O2 |
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Term
| What does hemoglobin bind? |
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Definition
O2 and CO
CO2 (kicks off O2 to diffuse into respiring tissue) binds to polypeptide
H+ (also kicks off O2)
bisphosphoglycerate BPG (Hb-BPG has lower affinity for O2 than hemoglobin alone, results in more O2 dumped into tissues) |
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Term
| gas exchange between tissues and blood |
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Definition
O2 diffuses down the PO2 gradient from alveolar spaces into lung capillaries and from systemic capillaries into tissues
CO2 diffuses down the PCO2 gradient from tissues to systemic capillaries and from lung capillaries to alveolar spaces |
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Definition
fetal hemoglobin has different globin chains and higher affinity for oxygen than does adult hemoglobin
adult: A2B2
fetal: A2Y2 |
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Term
| How to hold your breath a long time |
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Definition
have a lot of blood and store in spleen
have a lot of muscle myoglobin
dont work too hard |
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Term
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Definition
heart rate slows
vasoconstriction in extremity
splemic contraction
change in buoyency
less need to inhale; less sensitivity to lower blood pH |
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Term
| how can blood loss be stopped? |
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Definition
platelet plugs (form early)
fibrin clots (form later) |
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Term
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Definition
small, short-lived fragments of cells
do not respond to small vessel walls |
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Term
| what activates platelets? |
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Definition
collagen fibers
damage to vessel walls
atheroscherotic plaques |
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Term
| What happens when platelets are activated? |
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Definition
they become sticky and form a plug
They send signals for blood clotting |
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Definition
clot formation
smooth vessel walls
anticoagulants |
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Definition
clot formation
rough vessel walls
sluggish blood flow
Vitamin K |
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Term
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Definition
plasminogen which is activated by tissue plasminogen activator
plasmin -> dissolves clots |
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Term
| what does 'cooperativity' refer to in the context of the hemoglobin molecule? How does this cooperativity contribute to the function of hemoglobin? |
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Definition
The cooperativity of hemoglobin refers to the fact that each O2 molecule that binds to hemoglobin makes the binding of the next O2 easier
The way in which cooperativity contributes to hemoglobin's function can be seen in the dissociation curve. Hmeoglobin releases O2 to tissues that need it; the greater the need, the more O2 hemoglobin should release. this is what is seen in the curve. When the tissue;s PO2 decreases from 100mmHg to 80mmHg, hemoglobin's O2 saturation declines only from 98% to 95% - it does not release much O2. But when the tissue's PO2 goes from 40mmHg to 20mmHg, as it would during work or exercise, hemoglobin's saturation goes up from 70% to 35% - a 12 fold increase in the release of O2 compares to the previous situation |
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Term
| Why must erythrocytes be made continuously by the body from pluripotent stem cells? |
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Definition
| Erythrocytes encounter physical stresses in their movement through microcirculation that eventually destroys them. They have no repair capabilities, owing to their lack of nuclei and gene expression, nor can they divide to replace themselves, for the same reason. Therefor they must be made in the bone marrow at the same rate at which they are destroyed |
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| Agencies which monitor cheating in sports can require a hematocrit measurement for athletes as part of the testing procedure. Why? |
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Definition
| An athlete with an abnormally high hematocrit value would be suspected of taking doses of the hormone that increases production of red blood cells (erythropoietin EPO) which is against the rules |
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Term
| How does the binding of hemoglobin and O2 relate to the binding of hemoglobin and CO2? Hemoglobin and H=? How do these binding affinities help the body get O2 to tissues that need it most? |
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Definition
the binding of O2 to hemoglobin occurs with an inverse affinity to the binding of CO2 and H+ to hemoglobin. In other words, the binding of either CO2 or H+ to hemoglobin lessens the affinity of O2 for hemoglobin.
Since active tissues produce CO2, and since carbonic anhydrase in erythrocytes produces carbonic acid from CO2 and water, active tissues will produce two substances (CO2 and H+) that knock O2 off hemoglobin, making the O2 more available for uptake by the tissues |
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