Physio 3 Flashcards
what determines total amount O2 bound and carried by Hb?
% saturation Hb (amount O2 bound) and total [Hb] blood
Lower than normal blood [Hb] =
anemia
Describe relationship between PO2 and % Hb saturation
directly proportional
What’s shape/what variables determine (IV/DV) of O2-Hb dissociation (association) curve?
sigmoidal curve
% Hb saturation and PO2
B/c of cooperative binding of O2:
—0-40 mm Hg = large magnitude change in % saturation
—40-120 mm Hg = very small change in % saturation
normal systemic PO2 = 104 mm Hg (arterial) and 40 mm Hg (venous) –> thus, since arterial
Why will Hb never reach 100% saturation in systemic arterial blood?
due to chemical nature (kinetics) of molecules - constantly moving = constantly colliding (possibly forming bonds) and weak intermolecular interactions = constantly dissociating –> thus, all molecules are constantly forming bonds/dissociating
significance of “plateau at the right end” of O2-Hb dissociation curve and how does it act as safety factor?
Provide an example where safety factor would be useful.
Due to cooperative binding of O2 = large mag. change PO2 in arterial blood = small mag. change in % saturation
“plateau” = safety factor for supply O2 –> tissues if ever large decrease in PO2 of arterial blood (= decrease overall [O2] in blood)
example - regions HIGH ALTITUDE = LESS O2 = less O2 in alveoli = decrease net [O2] diffuses into arterial blood = decrease PO2 (O2 dissociated in blood plasma)
Describe how increase in altitude does not dramatically effect % saturation
high altitude –> O2 molecules in atmosphere farther apart (less dense, so inhale less O2 each breath) –> alveolar PO2 decreases –> systemic arterial PO2 decreases –> small decrease % saturation
due to “plateau at right end” dissociation curve - aka cooperative binding O2
If constant PO2, what 3 other variables effect % Hb saturation and why? What impact have on hemoglobin at molecular level?
Alter Hb affinity for O2 via altering bond strength
- changes in: [H+], [CO2], temperature, and [2,3-bisphosphoglycerate (2,3-BPG)
% Hb saturation =
( [HbO2] / total [Hb] ) X 100
Or
(# O2 molecules bound / total # O2 molecules total [Hb] capable of binding)
what determines % Hb saturation
affinity / bond strength between Hb & O2
List changes in variables that would cause O2-Hb dissociation curve to “shift to the right” (decrease % saturation):
- increase [H+]
- increase [CO2] (direct effect = increase [H+])
- increase temperature
- increase [2,3-bisphosphoglycerate]
How are metabolically active tissues able to “extract” more O2 from blood?
Increase [CO2] (carbohydrate metabolism / cell respiration product) –> increase [H+] –> decrease pH = local increase acidity –> local decrease Hb affinity O2 = local region causes increase HbO2 dissociation –> increased [O2] diffuse into metabolically active tissues
Increase temperature = decreased Hb affinity O2;
HEAT = product carbohydrate metabolism = metabolically active tissues = regions increase temperature
Metabolically active tissues create localized regions of increased [H+], increased [CO2], and increased temperature - all DECREASE Hb affinity to O2 = local increase HbO2 dissociation = increased [O2] diffusion into cells
How does increased [2,3-bisphosphoglycerate] effect O2 -Hb affinity? Give examples when elevated [2,3-BPG]
2,3-BPG binds to heme groups on Hb, decreases available binding sites on Hb –> decrease % Hb saturation
important for adaptation to poor blood flow certain regions/tissues or high altitude
How does carbohydrate metabolism increase [CO2] and subsequently [H+]?
C6H12O6 + O2 –> H2O + CO2 + ATP
Carbon dioxide reacts w/ H2O in blood create bicarbonate - equilibrium rxn = carbonic acid + H+
Blood circuit:
LEFT ventricle - aorta - systemic capillaries - superior and inferior venae cavae - RIGHT atrium
= Systemic blood circulation
Blood circuit:
RIGHT ventricle - pulmonary trunk - right and left pulmonary arteries - pulmonary capillaries - pulmonary veins (4) - LEFT atrium
= Pulmonary blood circulation
Total blood volume of adult?
5 liters
Hematocrit
List normal values (adult, male, female)
% total blood volume = RBCs
Average adult ~ 40%
Male ~ 43%
Female ~ 39%
Why is hematocrit different for males and females?
testosterone stimulates kidneys which produces more EPO = increase RBC production in bone marrow \
Only site of transport into or out of blood circulation:
crossing CAPILLARY WALLS
Does more blood pass through the systemic than pulmonary circuit in a given period of time?
NO - both pump same volume of blood/unit time
Rate = same
Portal circulatory pathway =
List examples
2 capillary beds in a series instead of 1 capillary bed.
heart - arteries - 1 capillary bed - blood vessel - 2nd capillary bed - veins - heart
ex. - Hypothalamus capillaries - blood vessel - anterior pituitary - 2nd capillaries; all digestive organ blood dumps into hepatic portal vessel - 2nd capillary bed
What is responsible for majority of ventricular filling?
gravity
why you can live with atrial fibrillation ~ weak primer pumps ~
List the formed elements of blood:
erythrocytes
leukocytes
platelets
all suspended in liquid called plasma