Ch. 14 + 16 Part 1 - Respiratory Physiology Flashcards
Define cardiac output (CO)
volume of blood pumped each minute by each ventricle
Define end-systolic volume (ESV)
volume of blood in the ventricles at the end of contraction
(volume is NEVER zero, is the lowest volume of blood in the ventricle at any point in the cardiac cycle; about 40% remains in ventricles after a contraction)
What describes the lowest volume of blood in the ventricle at any point in the cardiac cycle?
ESV (end systolic volume)
Define end diastolic volume (EDV)
volume of blood in the ventricles at the end of filling
(about 60% of EDV is ejected)
Define stroke volume (SV)
volume of blood ejected from the ventricles per beat (due to the contraction of the heart muscle); increases with increase contractility
(ex: if # of beats increase, SV will increase too)
What is the equation of cardiac output?
CO (ml/min) = SV (ml/beat) x HR (beats/min)
What are 4 factors that can affect HR?
What factor affects SV?
HR: ANS, hormones (ex: epi), fitness levels, age
SV: contractility
What is the average HR, SV, and CO?
HR = 70 bpm
SV= 70-80 ml/beat
CO = 5,500 ml/minute
CO of the left ventricle must ______ the output of the ________ ventricle so that the blood flow through both the __________ and __________ circuits are equal
equal
right
pulmonary
systemic
What is the eq for stroke volume (SV)?
SV = EDV - ESV
Define CO, ESV, EDV, SV. How are all of these related?
CO = SV x HR = (EDV-ESV) x HR
TRUE or FALSE: ESV is greater than EDV
False, ESV is the lowest volume of blood in the ventricle at any point in the cardiac cycle
What substance(s) function in keeping HCN channels open longer at the SA node? Is this controlled by SANS or PANS?
- norepinephrine
- epinephrine
- SANS (sympathetic)
What substance(s) function in opening K+ channels at the SA node? Is this controlled by SANS or PANS
- ACh
- PANS (parasympathetic)
Name the NTs involved in the sympathetic effect vs parasympathetic effect on the heart.
Explain how they carry out their effect on the heart
Sympathetic: norepinephrine and epinephrine -> keep HCN channels open -> PP slow increases -> increase HR
Parasympathetic: ACh -> open K+ channels -> PP slow to increase (less steep) -> decrease AP frequency -> decrease Ca2+ release -> decrease contractility and CO -> decrease HR
How does the SA node AP graph change under the influence of the sympathetic autonomic nervous system and why? (hint: what happens to PP?)
SA node AP graph will change in frequency (more AP produced)
SANS can release epinephrine which will produce cAMP. HCN channels are sensitive to cAMP and will stay open longer, causing more Na+ influx. This will increase/steepen the slope of the PP
Why would epinephrine increase heart rate (HR) and how does this happen?
Epinephrine increases heart rate because it produces cAMP which keeps HCN channels open longer
Sympathetic = epinephrine = ↑ cAMP = HCN channel stays open longer = Increase/steep slope of Pacemaker Potential = ↑ frequency of APs = ↑Ca2+ release from SR (of myocardial cells; nonspecialized) = ↑ # of contraction and CO = ↑HR
How does the SA node AP graph change under the influence of the parasympathetic autonomic nervous system and why? (hint- what happens to PP)
Parasympathetic = ACh = open K+ channel = ↓slope of PP = ↓frequency of APs = ↓ # of contraction and CO= ↓ HR
This is because ACh has an inhibitory effect on the SA node
Define hemoglobin (Hb) and how is it related to O2?
Hemoglobin: A complex protein (containing heme molecule; iron, and globin protein) that contains 4 subunits found in RBC
It is related to O2 as each of its subunits carries one O2 from the lungs to the rest of the body (each Hb can bind to 4 O2 molecules)
What is total O2 content dependent on?
PO2 and Hb concentration
PO2 is directly proportional to…
the amount of O2 availiable (PO2 measures O2 concentration)
What is another name for Hb-O2?
oxyhemoglobin
What is another name for Hb?
deoxyhemoglobin
What is another name for Hb-CO2
Carbaminohemoglobin
What is another name for Hb-CO
Carboxyhemoglobin
Define oxyhemoglobin
Hb-O2
Hb is bound to O2
Define deoxyhemoglobin
Hb
When O2 is released (unloaded) to the tissues
Define carbaminohemoglobin
Hb-CO2
Hb is bound to CO2
Define carboxyhemoglobin
Hb-CO
Hb is bound to carbon monoxide (CO)
Hb has a stronger bond with ______ than with ______
CO
O2
Why is carbon monoxide dangerous?
Hb has a stronger bond (high affinity) and prefers to bind with CO rather than O2, therefore reducing the ability of blood to carry O2
Define Percent Hb-O2 saturation.
What does it measure?
What is the normal %?
How is it measured?
% of Hb-O2 to total Hb
measured to assess how well the lungs have oxygenated the blood
97%
measured with pulse oximeter or blood-gas machine
Compare loading and unloading of O2
Loading of O2 = when Hb binds to O2 in the lungs
Unloading of O2 = when Hb-O2 releases (unloads) O2 in the tissue
Write a chemical reaction that can show loading and unloading of O2
Which way shows unloading and which way shows loading
deoxyhemoglobin (Hb) + O2 ⇌ oxyhemoglobin (Hb-O2)
moving left = unloading
moving right = loading
deoxyhemoglobin (Hb) + O2 ⇌ oxyhemoglobin (Hb-O2)
What does the direction of the reaction depend on?
PO2 of the environment (O2 concentration)
affinity for O2
Does a high PO2 favor unloading/release of O2 or favor loading/binding of O2?
unloading/release of O2
Does a low PO2 favor unloading/release of O2 or favor loading/binding of O2?
loading/binding
What shape best describes the curve of the oxygen-hemoglobin dissociation curve
sigmoidal (S-shaped)
At the _______ part of the curve, _________ changes produce __________ changes in % saturation
steep
small
large
You have two columns labeled as: O2 loading and O2 unloading. Under each column, place the following terms: high PO2, low PO2, high free O2, low free O2, high affinity, low affinity. Shift left or shift right?
O2 loading:
Low PO2
Low free O2
High affinity
Shift lefts
O2 unloading:
High PO2
High free O2
Low affinity
Shift right
Regarding the O2-Hb dissociation curve, what does P50 represent?
P50: PO2 (conc. Of O2) at which 50% saturation is achieved
Know the relationship between high/low PO2 to high/low affinity to unloading/loading of O2
high PO2 = low affinity = O2 unloading
low PO2 = high affinity = O2 loading
Understand the O2-Hb dissociation curve (know how to label it and what it means)
check slide 10 for how to draw curve
What does “free O2” mean and explain why it is free
Free O2 means the O2 are not bound to Hb (High PO2)
It is free because H+ broke the bond between Hb-O2, resulting in Hb-H+ + free O2
If person A has a certain P50 value, and person B has a higher P50 value, what does this tell you about the Hb of person B? How would the O2-Hb dissociation curve change for person B?
Person B has a low affinity between O2 and Hb, so the dissociation curve will be shifted to the right compared to person A
Under which situation(s) would the O2-Hb dissociation curve shift to the right and shift to the left, and explain why?
Shift to Left: (loading)
An increase in pH/decrease in H+
Decrease in pCO2
Decrease in temp
Shift to the right: (unloading)
A decrease in pH/increase in H+
Increase in pCO2
Increase in temp
What is the normal blood pH of a person?
pH 7.4
What pH indicates alkaline pH? Will the curve shift left or right?
~ pH 7.6
shift left
What pH indicated acidic pH?
Which way would the curve shift?
~ pH 7.2
shift right
Give a specific example/situation in which blood pH becomes alkaline and which way does the curve shift as a result? Explain
fetal Hb (Hb-F) will produce a more alkaline (basic) blood pH.
This is because fetus does not have developed lungs, so it depends on the O2 from the mother. The O2 wants to hang on TIGHTLY to Hb, resulting in a high affinity. This means the curve will shift left because high affinity means low PO2 value.
Give a specific example/situation in which blood pH becomes acidic and which way does the curve shift as a result? Explain
exercising skeletal muscle will create a more acidic blood pH
This is because the unloading of O2 from Hb to the tissues is needed. Unloading means affinity is low, so PO2 must be high, indicated by a shift to the right.
At alkaline pH (~pH _____) -> curve shifts ________ -> P5O _______ -> O2 affinity ___________ -> ___________ of O2 ________ Hb ______ the ________
~pH 7.6
left
decreases
increases
loading
to
at
lungs
At acidic pH (~pH _____) -> curve shifts ________ -> P5O _______ -> O2 affinity ___________ -> ___________ of O2 ________ Hb ______ the ________
~pH 7.2
right
increases
decreases
unloading
from
to
tissues
What is labeled on the x and y axis on the oxygen-hemoglobin dissociation curve
x axis: PO2 (mmHg) - partial pressure of O2
y axis: % O2 saturation of hemoglobin
What factors can change the affinity of Hb for O2
pH
temperature
What is the Bohr effect, and explain how it happens? (hint - see slide #14). Why does acidic blood lead to unloading of O2? Where does the free O2 go to and why?
Bohr effect is when the shift curve to the right due to pH changes (blood becomes acidic)
Acidic blood leads to the unloading of O2 because H+ go after the bonds between Hb and O2, causing free O2 and the bond between HB-H+. Free O2 goes from the RBC into the plasma and back into the tissue (gas exchange) to perform aerobic cellular respiration.
How will the P50 value change in regard to the Bohr Effect? Does the Bohr Effect allow for the loading or unloading of O2?
P50 value will increase because Bohr Effect leads to a shift to the right due to low pH/acidic blood
Bohr effect allows for the unloading of O2 from Hb, because O2 has low affinity to Hb and will unload from Hb to be given to the tissues for aerobic cellular respiration
Draw out the Bohr Effect. Draw out gas exchange, include any chemical reactions. Be able to describe what is going on
Do not need to include Chloride Shift/CO2 transport
check answer on slide 14
oxygenated blood finally reaches systemic capillaries. Tissues (ex: skeletal muscle) undergo cellular respiration, so they release CO2 as a waste product (must get rid of it)
CO2 enters blood plasma and enters the RBC
CO2 combines with H20 to form H2CO3 via cabonic anhydrase (CA; enzyme) -> then dissociates into H+ and HCO3- (bicarbonate) via CA (enzyme)
H+ ions starts to accumulate (more CO2 = more H+) which leads to a decrease in blood pH because blood becomes more acidic (pH 7.4 to pH 7.2)
Hb-O2 is inside the RBC (because it is oxygenated blood), but because H+ ions were made as a result of CO2 entering the RBC, it breaks the bond between Hb-O2, creating Hb-H+ and free O2. This is known as unloading because it broke the bonds and freed O2
Unloading O2 means a low affinity of O2 for Hb, which increases PO2 and P50 = SHIFT TO THE RIGHT
BOHR EFFECT!!
The free O2 leaves the RBC -> plasma -> enters tissue (ex: skeletal muscle) = GAS EXCHANGE
Check slide #14 on Ch. 14 and 16
H2CO3 is a _____ acid that will ________ into __________ and __________
weak
dissociate
HCO3-
H+
The chloride shift involves transport of ________
CO2
Draw and explain the chloride shift and how CO2 is transported out the RBC
CO2 is present in HCO3- and needs to be transported out of the RBC
It gets transported out by Band 3 which is a chloride-bicarbonate antiport (secondary AT) to ensure rxn proceeds to the right
HCO3- moves with the concentration gradient and Cl- moves against the concentration gradient
CHLORIDE SHIFT
Name the three options CO2 has at systemic capillaries (hint - where does it enter/become). Which is most common?
1) CO2 can dissolve in plasma
2) CO2 combines with hemoglobin
3) CO2 will bind with water and create H+ and HCO3-
TRUE or FALSE: Because of the chloride shift, the charge inside the RBC becomes more negative
False, although HCO3- is leaving the RBC, Cl- is entering the RBC to maintain electrical neutrality
What would happen to the concentration of extracellular Cl- if there was an inhibitor of carbonic anyhydrase (CA)
Without CA, rxn will not proceed so HCO3- will decrease (no more bicarbonate). Without bicarbonate, Band 3 will not work because movement of Cl- relies on the movement of HCO3- out of the cell (w/ concentration gradient). Because Cl- cannot move inside the RBC, extracellular Cl- will increase.
What is carbon monoxide?
a poisionous gas caused by burning of fossil fuels by faulty appliances/vehicles in an enclosed space
Be able to draw the oxygen hemoglobin curve with carbon monoxide posining effect.
check slide #17
Name the ways in which carbon monoxide affects the oxygen hemoglobin dissociation curve
curve will NEVER reach 100% O2 saturation of hemoglobin: because CO will never fall off of Hb (very dangerous)
O2 curve with CO effect shifts LEFT: any remaining O2 bound to Hb will want to hold on tightly to Hb because CO has a strong bond for Hb (therefore higher affinity of Hb for O2 -> left shift)
Why must CO2 be removed from the blood? (hint – what 2 things will CO2 form in the RBC and will one of these things change the pH of the blood?)
CO2 is toxic and needs to be removed from the body. CO2 will eventually form H+ and bicarbonate (HCO3-)
increases of H+ will cause the pH of the blood to decrease (become more acidic)
