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85 Cards in this Set

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Blood is the body's only _____ tissue.
fluid
Blood includes liquid plasma and formed elements such as
• Erythrocytes
• Leukocytes
• Platelets
• Plasma
Hemocrit
% of RBCs out of total blood volume (normally ~45%)
What are erythrocytes?
red blood cells (RBCs)
What are leukocytes?
white blood cells (WBCs)
What are platelets?
membrane bound cell fragments (w/ enzymes); involved in blood clotting
What is plasma?
non-living fluid matrix (H₂O + electrocytes), proteins, glucose, etc
What are the blood plasma components?
1) water ~ 92% of plasma
2) > 100 dissolved solutes:
a) plasma proteins
b) non-protein solutes
What are plasma proteins?
(~7% plasma), most produced in the liver
1) Albumin - most abundant (60% of plasma proteins)
2) Globulins - (35% plasma proteins)
3) Clotting proteins (4% plasma proteins)
4) Enzymes and Hormones (< 1% of plasma)
What are non-protein solutes?
(~ 1% of plasma)
1) Nutrients/waste products
2) Electrolytes (ions)
3) Gases (O₂/CO₂)
All formed elements are from stem cells in _____
bone marrow
Only _____ are "complete" cells
WBCs
What formed element has no nuclei, few organelles; platelets are just cell fragments?
RBCs
Most formed elements survive in the bloodstream for a few/many days.
few
Most blood cells do not divide are renewed by cells in _____.
bone marrow
Describe the structure of an erythrocyte.
• Biconcave discs
• Increased surface area for gas exchange (~30% more than a round cell)
• enables RBCs to bend & flex - squeeze through capillaries
• Anucleate - not a "true cell" and few organelles
• filled with hemoglobin (Hb) - protein that functions in gas transport
What is hemoglobin?
transports oxygen and carbon dioxide; makes RBCs red
Describe the structure of RBCs
Structure - complex, quaternary structure
• Globin (protein) + Heme (pigment complex)
• Globin = 2 alpha chains and 2 beta chains of polypeptides
• Each chain has 1 heme molecule with iron at the center
• 1 heme unit "holds" iron in a way that iron can interact with 1 oxygen molecule
Oxygen loading of hemoglobin occurs in the _____.
lungs
O₂ diffuses from ______ to blood, then through RBC to bind with hemoglobin
lung air sacs
When O₂ binds to iron, Hb becomes _____.
oxyhemoglobin changes to new 3-d shape → becomes ruby red
When O₂ detaches to iron, Hb becomes _____.
deoxyhemoglobin color changes to dark red
Hb transports ______ of oxygen in the blood (bound to iron of heme group)
~ 98.5%
Hb transports _____ of carbon dioxide in the blood (bound to globin)
~ 20%
What is carbaminohemoglobin?
when CO₂ bind to glob in's amino acids
Carbon dioxide loading occurs at the _____.
tissues
What is hematopoiesis?
blood cell formation in the red bone marrow
What is hemocytoblasts?
blood stem cells
• produce all formed elements (RBCs, WBCs, and platelets)
Regulation & Requirements for Erythropoiesis
Circulating Erythrocytes - number remains constant and reflects balance between RBC production/destruction
• too few RBCs leads to tissue hypoxia
• too many RBCs causes high blood viscosity
Erythropoiesis is _____ controlled
hormonally
Erythropoietin (EPO) released by the kidneys is triggered by:
• Tissue hypoxia (due to decreased RBCs)
• Decreased O₂ availability
• Increased tissue demand for O₂
↑ erythropoiesis increases the:
• RBC count in circulating blood
• O₂ carrying ability of the blood
Erythropoietin Mechanism
Homeostasis: Normal blood oxygen levels
Stimulus: Hypoxia due to decreased RBC count, decreased amount of hemoglobin, or decreased availability of O₂
What are two erythrocyte disorders?
anemia and polycythemia
What is anemia?
blood has normally low oxygen-carrying capacity

**It is a symptom rather than a disease itself

• Blood oxygen levels cannot support normal metabolism
• Signs/Symptoms include fatigue, paleness, shortness of breath, and chills
What is polycythemia?
excess RBCs that increase blood viscosity

Three main polycythemias are:
1) polycythemia vera (up to 80% hematocrit), bone marrow cancer
2) secondary polycythemia (decrease oxygen availability/excess EPO)
3) blood doping
Blood plasma can't transport enough O₂ or CO₂ to meet physiological needs
• O₂ & CO₂ have limited solubilities in blood plasma
• Tissues need more O₂ & generate more CO₂ than can be absorbed or transported
Blood plasma can't transport enough O₂ or CO₂ to meet physiological needs and the problem is solved by:
Red Blood Cells (RBC)
• Transport O₂ to, and CO₂ from peripheral tissues
• Remove O₂ and CO₂ from plasma, allowing more gases to diffuse into blood
O₂ Transport

Molecular O₂ is carried in the _____:
blood
• bound to hemoglobin (in RBC)
• dissolved in plasma
O₂ Transport

O₂ binds to iron in hemoglobin (Hb) molecules:
in a rapid & reversible reaction
O₂ Transport

Each RBC has about _____ million Hb molecules:
280 million

• each binds 4 oxygen molecules
O₂ Transport

• Hb-O₂ combination is
oxyhemoglobin (HbO₂)
O₂ Transport

• Hb that has released O₂ is
deoxyhemoglobin (HHb)
O₂ Transport

Each RBC has about _____ million Hb molecules:
280 million

• each binds 4 oxygen molecules
What is hemoglobin saturation?
percentage of heme units (collectively) in a hemoglobin molecule with bound O₂
O₂ Transport

• Hb-O₂ combination is
oxyhemoglobin (HbO₂)
All 4 heme units bound with O₂ is _____ saturation
100%
O₂ Transport

• Hb that has released O₂ is
deoxyhemoglobin (HHb)
Each Hb (on average) carries 2 O₂ molecules is _____ saturation
50%
What is hemoglobin saturation?
percentage of heme units (collectively) in a hemoglobin molecule with bound O₂
What are the environmental factors affecting the rate of Hb binding/releasing of O₂?
1) PO₂ of blood
2) Blood pH
3) Temperature
4) Metabolic activity within RBCs
All 4 heme units bound with O₂ is _____ saturation
100%
How does hemoglobin and PO₂ affect the rate of Hb binding?
• Hb is almost completely saturated at a PO₂ of 70 mm Hg
• further increase in PO₂ = small increases in O₂ binding
Each Hb (on average) carries 2 O₂ molecules is _____ saturation
50%
What is oxygen-hemoglobin saturation curve?
a graph relating the saturation of hemoglobin to PO₂

• rightward shift means more O₂ will be unloading from Hb at a given PO₂
• in active tissues, ↑ temperature, ↓ pH and ↑ PCO₂ promote unloading of O₂
What are the environmental factors affecting the rate of Hb binding/releasing of O₂?
1) PO₂ of blood
2) Blood pH
3) Temperature
4) Metabolic activity within RBCs
Hemoglobin and PO₂ is a curve rather than a straight line because
• Hb changes its shape each time O₂ molecule binds
• allows Hb to bind O₂ when O₂ levels are low
How does hemoglobin and PO₂ affect the rate of Hb binding?
• Hb is almost completely saturated at a PO₂ of 70 mm Hg
• further increase in PO₂ = small increases in O₂ binding
What is oxygen-hemoglobin saturation curve?
a graph relating the saturation of hemoglobin to PO₂

• rightward shift means more O₂ will be unloading from Hb at a given PO₂
• in active tissues, ↑ temperature, ↓ pH and ↑ PCO₂ promote unloading of O₂
Hemoglobin and PO₂ is a curve rather than a straight line because
• Hb changes its shape each time O₂ molecule binds
• allows Hb to bind O₂ when O₂ levels are low
Hemoglobin and PO₂

Carbon monoxide (CO) from burning fuels:
• binds strongly to hemoglobin and takes place of O₂
• can result in carbon monoxide poisoning
How does hemoglobin and pH affect the oxygen-hemoglobin saturation curve?
standarized for normal blood (pH 7.4, 37°C)
• When pH drops → more O₂ is released (curve shifts to right & downward)
∙ causes a decrease in oxygen's binding affinity
• When pH rises → less O₂ is released (curve shifts to the left & upward)
How does hemoglobin and temperature affect the oxygen-hemoglobin saturation curve?
standarized for normal blood (pH 7.4, 37°C)
• When temperature rises → more O₂ is released (curve shifts to the right & down)
• When temperature drops → less O₂ is released (curve shifts to the left & up)
Hemoglobin and temperature
When pH drops or temperature rises:
more oxygen is released (curve shifts to the right)
Hemoglobin and temperature
When pH rises or temperature drops:
less oxygen is released (curve shifts to the left)
Hemoglobin and pH

active tissues generate ____ which lowers the pH of _____
acids; interstitial fluid
Hemoglobin and pH

A decrease in pH changes the shape of _____
Hb
Hemoglobin and pH

Shape change = release of ____ by Hb
O₂ which causes the Hb saturation to decline
Hemoglobin and temperature

An increase in temperature causes Hb to release more _____
O₂
Hemoglobin and

A decrease in temperature causes Hb to bind to _____ more tightly
O₂
How does hemoglobin and BPG (RBC metabolic activity's effect on Hb) affect the binding and release of O₂?
RBC (lack mitochondria) generate ATP by glycolysis which forms lactic acid and BPG (2,3-biphosphoglycerate)

BPG directly affects O₂ binding and release

↑ BPG → ↑ O₂ release
What are the key concepts of hemoglobin in RBC in O₂ Transport?
• carries most blood oxygen
• Hb releases bound O₂ in response to low O₂ partial pressure in surrounding plasma
If PO₂ increases, hemoglobin _____ oxygen
binds
If PO₂ decreases, hemoglobin _____ oxygen
releases
At a given PO₂: hemoglobin will release additional oxygen if:
• pH decreases or
• temperature increases or
• BPG increases
What is the Bohr effect?
effect of pH on hemoglobin saturation curve (caused by CO₂)

1. CO₂ rapidly diffuses into RBCs once in the blood
2. in RBC, carbonic anhydrase (enzyme) catalyzes a reaction with H₂O to produce carbonic acid (H₂CO₃)
3. Carbonic acid (H₂CO₃) dissociates into hydrogen ion (H+) and bicarbonate ion (HCO₃-)
4. Increase in H+ = decrease in pH
↑ CO₂ causes the reaction to proceed to the _____
RIGHT
↓ CO₂ causes the reaction to proceed to the _____
LEFT
According to the Bohr effect, how does an increase in CO₂ affect the binding affinity of O₂?
add answer here
CO₂ is generated as a byproduct of _____.
aerobic metabolism (cellular respiration)
CO₂ in the bloodstream may be:
1. converted to carbonic acid
2. bound to protein portion of hemoglobin
3. dissolved in plasma
CO₂ in the bloodstream

___% transported as bicarbonate (HCO₃-)
• carbonic acid (H₂CO₃) quickly dissociates into H+ * HCO₃-
___% bound to Hb molecule forming carbaminohemoglobin
___% transported as CO₂ dissolved in plasma
70%, 23%, and 7%
Bicarbonate ions move into plasma by an exchange mechanism called the ______ that takes in Cl- ions without using ATP
chloride shift

counterbalances negative bicarbonate ions from RBCs
CO₂ travels in the bloodstream primarily as bicarbonate ions, which form through dissociation of carbonic acid produced by ______ in RBCs
carbonic anhydrase
Lesser amounts of CO₂ are bound to _____ or dissolve in the _____
Hb; plasma