EXAM 4 Flashcards
(34 cards)
FICK DIFFUSION EQUATION
K x A x (P2-P1/D)
K= DIFFUSION COEFFICIENT (200,000 GREATER IN AIR THAN WATER)
A= AREA
P2-P1= GRADIENT
D= DISTANCE
TUNA: greater SA and flow
TROUT: Significantly greater thickness
Be able to describe how mammalian respiratory systems moves air from the outside
into the lungs.
INHALATION: muscles contract, volume increases, pressure inside falls so air flows in
EXHALATION: muscles relax, volume decreases, pressure inside rises so air flows out
The diaphragm functions as a thin muscular sheet that controls the regulate the volume inside the chest cavity (separates the chest and abdominal cavities)
Be able to calculate respiratory minute volumes
Respiratory minute volume = Tidal volume (mL) x breathing rate (BPM)
Be able to describe characteristics (4 things) and function of the bird lung that allow it to
perform so well at high altitudes compared to mammals
One way airflow
Large areas of gas exchange
Barrier thickness
countercurrent
Be able to calculate the partial pressure of Oxygen at any altitude given the atmospheric
pressure
@ sea level (760mm Hg)
N= 0.78 x 760
O= 0.2094 x 760
CO2= 0.0004 x 760
Know the 4 things that affect the concentration of a gas in solution
Temperature
Solutes present
Pressure
Solubility
Be able to describe the characteristics of the hemoglobin molecule
tetrameric protein and heme group
sigmoidal binding curve
One binding oxygen causes an increase in affinity for the rest
Be able to describe the hemoglobin binding curve and why it is S shaped. Why is the
shape important for loading and off-loading Oxygen? What is subunit cooperativity?
The hemoglobin binding curve in a S curve because the binding of one oxygen will cause a conformational change and thus increase the likelihood of other oxygen atoms binding. COOPERATIVITY
Be able to compare the affinities of different hemoglobin molecules and myoglobin and
describe them based on their P-50s
(on graph): start at the left and read down
What environmental factors affect the affinity of Hb for oxygen? Which way do they
shift the binding curve? Why are they important to loading and unloading oxygen? Acid
Bohr effect, gaseous Bohr effect
REDUCED AFFINITY (right shift) : increase in temperature
binding of organic phosphates DPG and ATP
decrease in pH (BOHR SHIFT)
increase in CO2 conc.
Why does Myoglobin have a hyperbolic binding curve? What is Mb’s function? Why is
its affinity for Oxygen so high?
single heme group
stores oxygen for working muscles
proximal histidine group helps oxygen bind and it binds more tightly
non cooperative binding
Why is breathing carbon monoxide a problem. How does it affect oxygen transport by
the blood?
Hb has a significantly greater affinity for CO (200x) than for O2
Be able to the describe differences between fetal and maternal Hb and how their
affinities differ. Why is this important?
Fetal has a higher affinity over maternal
Fetal hemoglobin contains 2 alpha and 2 gamma subunits
What other molecules bind to hemoglobin? How do they affect the affinity of Hb for
O2?
CO
How does the blood carry carbon dioxide? What are the pools and their size?
Dissolved in plasma 5%
Bound to hemoglobin 5%
Dissolved in plasma as bicarbonate 90%
Be able to describe what happens to CO2 as it diffuses from the tissues into the blood
- CO2diffuses out of tissues and into RBCs.
- CO2in RBCs forms HCO3-and binds to Hb forming
carbamino groups (SEE EQUATION) - O2 is off loaded from RBCs as Hb O2 affinity decreases
(BOHR SHIFT) with decreasing ph and the presence of
CO2 - H+ ion concentration is buffered by anion binding by Hb
and other proteins
Be able to describe how the “law of mass action” drives bicarbonate formation when
the blood is in the tissues and how it drives the formation of CO2 when the blood passes
through the lungs. Why is carbonic anhydrase important to this process?
carbonic anhydrase catalyzes the formation of bicarbonate and hydrogen ions from carbon dioxide and water it is important because…
1.The protons produced by the enzyme-catalyzed reaction induce the Bohr shift, which makes hemoglobin more likely to release oxygen.
2. The partial pressure of CO2 in blood drops when carbon dioxide is converted to soluble bicarbonate ions, maintaining a strong partial pressure gradient favoring the entry of CO2 into red blood cells
How is Bicarbonate move back and forth from the plasma and red blood cells? Why is
this important? What happens to the H+ ions that a formed? Why is this important?
“When hemoglobin is carrying few oxygen molecules, it has a high affinity for protons. As a result, it takes up much of the H+ that is produced when carbon dioxide reacts with water.”
AT THE LUNGS
O2 diffuses across respiratory surfaces and binds to Hb.
2. As O2binds to Hb, H+ are released lowering ph.
3. This pushes the formation of CO2in the RBCs ( SEE
EQUATION).
4. This pushes the diffusion of CO2out of the system and
the release of CO2from Hb amino groups (increasing the
affinity of Hb for O2).
5. Carbon anhydrase catalyses the formation of CO2in the
RBCs and lung endothelium and epithelium.
Be able to describe how open and closed circulatory systems differ
Open circulatory system- (many invertebrates have an open system) heart pumps into an
open space, the hemocoel, which lies between the endoderm and ectoderm. The
hemolymph is not moved through capillaries, but directly bathes the tissues. Hemocoel
may be 20-40% of body volume and hemolymph 30% of body volume. Pressures are low
4-10 mmHg
Closed circulatory system- the fluid within closed systems is blood and the system is
composed of a set of vessels, blood differs in composition from the other extracellular
fluid. There is also a lymphatic system for returning filtered materials back to the
circulation. Blood typically 5-10% of total body volume. Pressures high systolic 120;
diastolic 80 mm Hg
Be able to describe the flow of blood through the mammalian heart and the specific
roles of the left and right atria and ventricles as well as the role of the aorta? Be able to
calculate cardiac output. What is the Frank-Starling mechanism?
atrium»ventricle»artery
valves allow for one direction of flow
left/right atria: chamber that receives blood
left/right ventricle: chamber of heart which generates the force required to propel blood out of the heart
aorta: larger artery made of mostly elastic fibers CO= SV (mL) x HR (BPM)
FRANK: ability of the heart to change it’s force of contraction and therefore SV in response to changes in venous return
Be able to describe to describe the three muscle cell types found in the heart and their
properties. What are intercalated discs?
PACEMAKER: SA and AV node, auto-rhythmic and weakly contractile
CONDUCTION: larger, weakly contractile, inner wall of ventricles, fast conduction of AP
MUSCULAR PUMP: int. size, strongly contractile and comprise the major portion of the heart muscle
INTERCALATED DISCS: contain gap junctions which connect cells to cell allowing electrical signals to directly pass from one cardiac muscle to the next
Be able to describe how pacemaker cells work and how they produce a rhythmic
contract of the heart. Be able to trace the electrical signal from point to point in the
heart.
initiate contraction in the heart
SA NODE
1. signal originates in SA node (depolarization)
2. signal spreads over atria
3. signal is delayed in the AV node
4. signal spreads along conducting fibers to bottom and top of ventricles; ventricles contract due to simultaneous depolarization
5. ventricles relax
Be able to describe how blood flow and pressure are affected blood vessel size (radius).
Know the Poiseuille-Hagan equation and how to predict changes in flow with changes in
conditions
Flow rate= (Pin-Pout)pir^4/8n*L
n= viscosity
r= radius
L= length
