Exam 2 Flashcards
Cardiac and Pulmonary Physiology in Exercise (210 cards)
1
Q
What is the path of blood flow through the heart?
A
Blood flows from the right atrium to the right ventricle, then to the lungs, returns to the left atrium, flows into the left ventricle, and is pumped into the aorta.
2
Q
What is the role of the SA node in cardiac conduction?
A
The SA node, located in the right atrium, depolarizes and acts as the intrinsic pacemaker of the heart.
3
Q
What happens after the electrical impulse spreads through the atria?
A
The atria contract.
4
Q
What occurs at the AV node during cardiac conduction?
A
The electrical impulse is transmitted to the AV bundle (bundle of His) and Purkinje fibers.
5
Q
Why does the conduction velocity change especially at the AV node?
A
To ensure that the atrium and ventricles do not contract at the same time
6
Q
Which part of the heart is responsible for the ventricles contracting when referring to the electrical conduction?
A
The Purkinje fibers
7
Q
What is the relationship between electrical events and mechanical events in the heart?
A
P-wave correlates with atrial depolarization and contraction; QRS complex with ventricular depolarization and contraction; T-wave with ventricular repolarization and relaxation.
8
Q
Why is there no electrical event for atrial relaxation?
A
It occurs simultaneously with the QRS complex.
9
Q
What factors control heart rate?
A
- Sympathetic Nervous System (increases HR)
- Parasympathetic Nervous System (decreases HR)
- Hormones (mostly increase HR)
10
Q
Which neurotransmitter is responsible for parasympathetic control of the cardiac muscle?
A
Acetylcholine (Ach)
11
Q
What anatomical component of the nervous system is responsible for parasympathetic control of the cardiac muscle?
A
The vagus nerve
12
Q
What is the definition of systole?
A
Systole is the contraction phase of the heart during which the heart’s chambers expel blood.
13
Q
What is the normal Brachial systolic blood pressure?
A
Normal systolic blood pressure is 120-130 mmHg.
14
Q
What is diastole?
A
Diastole is the relaxation phase of the heart during which the heart’s chambers fill with blood.
15
Q
What is the normal Brachial diastolic blood pressure?
A
Normal diastolic blood pressure is 70-80 mmHg.
16
Q
What is End Systolic Volume (ESV)?
A
ESV is the volume of blood remaining in the ventricle after a contraction.
17
Q
What is End Diastolic Volume (EDV)?
A
EDV is the volume of blood in the ventricle at the end of diastole, just prior to ventricular contraction.
18
Q
What is Stroke Volume (SV)?
A
SV is the volume of blood ejected by the heart in a single beat.
19
Q
How is Cardiac Output (Q) calculated?
A
Cardiac output is calculated as Q = heart rate x stroke volume.
20
Q
What is Ejection Fraction (EF)?
A
EF is the percentage of the total blood volume pumped out of the left ventricle after contraction.
21
Q
How is the ejection fraction calculated?
A
(SV/EDV) * 100
22
Q
What factors control Stroke Volume?
A
- Venous return
- Preload (Frank-Starling mechanism)
- Afterload
- Contractility
23
Q
What does the Frank-Starling mechanism describe?
A
The relationship between the initial length of a muscle and its ability to develop force or tension during contraction.
24
Q
How is the ventricular muscle different from skeletal muscle relating to the Frank Starling Mechanism?
A
There is a uniquely greater force generated when the ventricle is stretched with filling. (More fill =More stretch = more force output). Unlike skeletal muscle that when overly stretched produces less force output
25
How does afterload affect the heart?
Afterload is the pressure against which the ventricles must push blood.
26
What is another word for inotropy and what is it related to the heart muscle?
The force with which the ventricular muscles contract and squeeze
27
What influences ESV in the heart? which physiological factors influence it?
Afterload and contractility; influenced by aortic pressure, age, arterial stiffness, sympathetic stimulation, increased heart rate, and inotropic agents (digitalis).
28
Which factors influence EDV? how?
Preload and Venous return; muscle pump, breathing, valves within veins, and compliance of ventricular wall
29
Which factors affect ESV?
Afterload and Contractility (inotropy)
30
What happens to ESV if contractility increases?
ESV decreases.
31
What happens to SV if ESV decreases?
SV increases.
32
If venous return decreases, what happens to EDV and SV?
Both decrease
33
If afterload increases, what happens to ESV and SV?
ESV increases and SV decreases
34
If preload increases, what happens to EDV and SV?
Both increase
35
If contractility increases what happens to ESV and SV?
ESV decreases and SV increases
36
What is the normal resting heart rate for a healthy individual?
60-80 bpm.
37
What is the resting heart rate for elite endurance athletes? why?
35-45 bpm. higher parasympathetic drive, same Q at rest, higher SV)
38
What is the normal stroke volume for a resting individual?
60-80 mL/beat.
39
What is the normal SV for an elite endurance athlete at rest? why?
100-125 mL/beat; most importantly due to increased ventricular compliance --> increased preload and higher contractility
40
What is the SV of a normal individual during max exercise?
120-130 mL/beat
41
What is the SV of an elite endurance athlete during max exercise?
175-200 mL/beat
42
Pertaining to the difference in stroke volumes at rest and during maximal exercise in normal individuals and elite endurance athletes, which has a bigger influence? EDV or ESV?
EDV, filling is more important than squeezing
43
What is the Cardiac Output (Q) at rest for normal individuals vs. Elite endurance athletes?
5 L/min, they consume the same at rest
44
What is the maximum cardiac output during exercise for a normal individual? What about for an elite endurance athlete? What accounts for the difference?
20-25 L/min (normal); 30-35 L/min (elite); due to SV not HR
45
The values for Q and SV were average values, what other variable influences these values?
Body size
46
What effect does gravity have on blood pressure measurements when taken at the calf?
Systolic BP would be 15 mmHg higher due to gravity (as long as you were standing up)
47
What are the 7 phases of the cardiac cycle?
1. Atrial Systole
2. Isovolumetric Contraction
3. Rapid ventricular ejection
4. Reduced Ventricular Ejection
5. Isovolumetric Relaxation
6. Rapid Filling
7. Reduced Filling
48
What electrical event is associated with atrial systole?
P wave (atrial depolarization)
49
What happens to the volume of the LV during atrial systole?
Increases, as blood is pushed through the mitral valve from the atria to the ventricle
50
What happens to pressure in the LA and LV during atrial systole
LA and LV increase slightly due to the contraction of atria and filling of ventricle
51
What happens to LV volume during isovolumetric contraction? why
No change in LV volume despite ventricular contraction. Because not enough pressure is generated to open the aortic valve
52
What is the electrical event associated with Isovolumetric Contraction?
QRS complex
53
What happens to pressure in the LA and LV during isovolumetric contraction?
Steep rise in LV due to contraction but not enough pressure to open the aortic valve; small increase in LA pressure due to filling of the LA from the pulmonary system
54
What happens during rapid ventricular ejection?
LV pressure increases, exceeding aortic pressure thus ejecting blood causing a rapid decrease in LV volume. Small decrease in LA pressure as some blood trickles into the ventricle
55
What electrical event is associated with Reduced ventricular ejection?
T wave
56
What happens to LV volume and pressure during Reduced Ventricular Ejection phase?
LV pressure peaks and then declines; LV volume continues to decrease
57
Why does LV volume continue to decrease even though the ventricle is relaxing?
The rapid ejection phase is so fast there is a kinetic energy generated creating a siphoning action
58
What happens during isovolumetric relaxation?
LV pressure falls below aortic pressure, aortic valve closes, LV volume remains constant, small increase in LA pressure
59
Why is there a small increase in LA pressure during Isovolumetric Relaxation?
Because blood is entering through the pulmonary system but cannot be released into the ventricle due to lower atrial pressure than ventricular pressure
60
What happens during rapid filling of the heart?
LA pressure exceeds LV pressure opening the mitral valve and LV volume rises quickly.
61
How does LV volume rise quickly during the rapid filling stage even though the atria are not contracting?
The pressure gradient drives flow and there is some filling even without atrial contraction
62
What happens during reduced filling of the heart?
Rate of LV slows due increased elastic recoil resisting the filling of the ventricle. Gradual increase in LA and LV pressure pressure
63
What is EDPVR and what is it dependent on?
End diastolic pressure-volume relationship; depends on ventricular compliance
-Stiff (low compliance) = higher pressure
- Loose (high compliance) = Lower pressure
64
Referring to the EDPVR does high or low compliance result in better heart function?
High compliance since increased heart function is generally due to ventricular filling rather than ejection
65
What is ESPVR? what is it dependent on?
(End systolic pressure-volume relationship) max pressure that can be developed by the ventricle at any given ventricular volume; depends on contractility
66
How is the ESPVR line related to the pressure volume loop?
The loop can NOT cross over this line
67
How does contractility influence ESPVR?
Increased contractility = higher heart function
Decreased contractility = heart failure
68
How does increased Preload influence the pressure-volume relationship of the heart?
↑venous return, ↑preload, same afterload (aortic valve opens at same pressure)
Greater LV volume is ejected and ESV stays the same assuming afterload and contractility remain unchanged
↑EDV and ↑SV
69
How does increased afterload affect the pressure volume relationship of the heart?
↑pressure required to open aortic valve
ESVPR line is met at a higher LV volume --> ↑ESV
Slightly higher EDV with filling, not due to increased compliance, but because of a greater starting point for filling
Overall: increase ESV and decrease SV
70
How does an increase in contractility (inotropy) affect the pressure volume relationship of the heart?
↑ slope of ESPVR line met at a ↓LV volume ---> ↓ESV
Greater reduction in LV volume until aortic valve closes
Overall: ↑SV because ↓ESV
71
What is the relationship between VO2 and Workload (pace or speed)?
directly proportional
72
What is the relationship between Q and workload? what is the saying?
A little bit of a cuve but generally directly proportional
"Cardiac Output follows VO2)
73
What is the relationship between HR and Workload?
Directly proportional
74
What is the relationship between SV and workload?
In untrained or moderately trained athletes, SV plateaus at ~ 40-60% of max
In highly trained endurance athletes, SV continues to rise throughout exercise
75
What is the increase in SV during early (low intensity) exercise generally due to?
Increase in venous return and preload --> higher EDV
76
For moderately trained or untrained individuals, what would account for an increase SV during peak exercise?
increased ventricular contractility (slightly reducing ESV).
With peak exercise, there is a decrease in diastolic filling time - preload and EDV stay constant
77
Why do elite endurance athletes continue to increase SV at high workloads?
1. Greater ventricular compliance (small effect)
2. More effective muscle pump causing venous blood to be "injected" into the heart during diastole (majority of effect)
78
what is the relationship Between cardiac output and lie, sit, stand, walk, jog, and run?
lie=sit=stand
run>jog>walk
"Cardiac output follows VO2"
79
what is the relationship between Stroke Volume and lie, sit, stand, walk, jog, and run?
Lie>sit>stand - Venous return decreases due to gravity thus decreasing EDV
Lie>walk>sit and stand
jog = run (in untrained/moderately trained athletes)
80
what is the relationship between HR and lie, sit, stand, walk, jog, and run?
((lie
81
Why does HR go up a little from lie to sit to stand?
1. Reduction of parasympathetic nervous system
2. Q stays the same, SV decreases, therefore HR has to increase
82
What is the increase in Q from jog to run due to? SV or HR?
almost 100% due to HR because Q increases, SV stays the same (in moderately trained/untrained individuals) therefore HR has to increase
83
What variables must be tightly matched to make sure BP is maintained?
Vasodilation in the arterial system, vasoconstriction in the venous system, HR and SV at the start of exercise (or change from laying to sitting/standing)
84
What is the relationship between systolic and diastolic blood pressure during dynamic exercise?
Systolic values rise significantly while diastolic values show little to no rise
85
What is the relationship between systolic and diastolic blood pressure during static exercise?
Both systolic and diastolic BP will increase substantially compared to resting values
86
What is Poiseuille’s Law?
Flow = pressure gradient / resistance.
87
Which variables are easiest to change to affect blood flow?
1. Changing the radius of the vessel. (BY FAR)
2. Pressure gradient
3. Viscocity
88
What happens to stroke volume during early exercise?
Increases primarily due to increased venous return and preload.
89
What is the effect of high-intensity exercise on stroke volume in elite endurance athletes?
Stroke volume continues to rise.
90
What is the primary reason for stroke volume plateauing at 40-60% of max for untrained individuals?
A decrease in diastolic filling time.
91
What happens to blood pressure during dynamic exercise?
Systolic BP increases while diastolic BP may remain stable.
92
What is the effect of lying to standing on stroke volume?
SV decreases due to decreased venous return.
93
What primarily controls the distribution of blood to various areas of the body?
Arterioles
## Footnote
Arterioles can change diameter through vasoconstriction and vasodilation.
94
What are the local control factors influencing blood flow?
* Oxygen demand
* CO2 (directly proportional)
* H+ (directly proportional)
* NO (nitric oxide)
## Footnote
Local control is also known as autoregulation.
95
What is local control of bloodflow?
autoregulation that does not involve the CNS
96
How does NO (nitric oxide) influence control of blood flow?
As Q increases, blood hits the endothelium activating eNOS which releases NO, further vasodilating the vessels
97
What does systemic control of blood flow involve?
Nervous system influence
## Footnote
Systemic control is termed extrinsic control.
98
How does the sympathetic nervous system affect blood flow during exercise?
Causes vasoconstriction in inactive tissues
## Footnote
This enhances venous return, allowing more blood to reach active tissues.
99
Where is most of the blood at rest?
In the veins (2/3) - act as a reservoir
100
What role do valves in veins play?
Ensure one-way flow
## Footnote
Valves prevent backflow, aiding in venous return.
101
Veins are very compliant, so how does blood return back to the heart?
Via a muscle pump that causes a 'milking action'
102
What is the distribution of cardiac output during rest and exercise for the skin?
Directly proportional until maximal exercise, then inversely proportional
## Footnote
At maximal exercise, blood flow to skeletal muscle is prioritized over thermoregulation.
103
Which organ receives the most blood flow at rest?
Kidneys
## Footnote
The kidneys are highly vascularized, receiving a significant portion of cardiac output.
104
What is plasma?
The liquid portion of the blood
## Footnote
Plasma contains water, electrolytes, proteins, and waste products.
105
What is hemoglobin (Hb)?
Iron-containing protein found in the blood that binds and transports O2
## Footnote
Hemoglobin levels are measured in grams per deciliter of blood.
106
What are the units for [Hb]?
g Hb/dL; grams per TOTAL blood volume
107
What is hematocrit (Hct)?
Ratio of RBCs to total blood volume
## Footnote
Hematocrit is expressed as a percentage.
108
Typical hematocrit values for men and women
* Men: 47%
* Women: 43%
## Footnote
Women typically have lower values due to menstrual blood loss and dietary factors.
109
Typical [Hb] for men and women
Men - 15 g/dL
Women - 14 g/dL
110
Why are values for [Hb] and Hct lower for women than men?
-Menstrual Blood loss
-Diets that contain less red meat and other iron rich protein sources
111
Why is folic acid important for women of childbearing age?
Prevents birth defects
## Footnote
Low folic acid levels are linked to neural tube defects.
112
Why is hematocrit and [Hb] not always the best predictor of blood health and determining RBC count?
They are ratios and concentrations so there could be misalignments with lower and higher plasma to RBC counts
113
What happens to blood volume with training?
Total volume increases primarily due to increases in plasma; increases in RBC volume are small
## Footnote
This increase is driven by higher ADH levels and plasma proteins.
114
What is cardiac drift?
Changes in cardiac variables during prolonged, submaximal exercise at constant workload
## Footnote
Cardiac drift includes changes in stroke volume and heart rate over time.
115
What happens to blood volume during prolonged exercise?
Decreases due to loss of plasma from sweating and hemoconcentration where plasma shifts out of the blood into the interstitial space due to osmotic pressure
## Footnote
Hemoconcentration occurs as plasma shifts into the interstitial space.
116
what is hemoconcentration?
Increased concentration of RBC's due to loss of plasma
117
What is the relationship between stroke volume and heart rate during cardiac drift?
Stroke volume decreases while heart rate increases
## Footnote
To maintain cardiac output (Q) during exercise.
118
What is the formula for Blood Pressure?
BP = Q * TPR
119
What happens to systemic arterial and pulmonary arterial pressure (Blood Pressure) during cardiac drift?
Decreases; Q stays the same but TPR decreases due to vasodilation in skin and skeletal muscle
120
How does being hydrated affect skin blood flow?
In a hydrated state, more blood flow can go to the skin and aid in thermoregulation
121
How can we maintain HR during cardiac drift with clients?
Slow down over the course of the bout
Maintain a hydrated status (more than just drinking when they feel like it)
Control environmental conditions (temp)
122
What are the two ways to calculate VO2
Direct Fick and Indirect Calorimetry/Gas Exchange
123
What is the Fick equation for calculating VO2?
VO2 = Q x a-vO2 difference
## Footnote
This equation relates cardiac output and the difference in oxygen content between arterial and venous blood.
124
What is the a-vO2 difference determined from?
The difference between arterial O2 and mixed venous O2
125
What is mixed venous O2? Why is it used?
Pooled blood from the right side of the heart (vena cavae) which comes from the entire systemic circuit. This represents whole body oxygen extraction as opposed to looking at one area of a muscle which may use more oxygen thus leading to skewed results
126
During cycle exercise, how does oxygen content differ between blood sampled from the radial artery and femoral artery? Why?
Radial artery has the same oxygen content as the femoral artery; Blood hasn't reached the capillaries yet so there is no exchange of gases
## Footnote
The answer is typically lower due to less oxygen extraction in the arm.
127
Blood sampled from the antecubital vein (arm) will have _____ oxygen content than blood sampled from the femoral vein (leg). Why?
Higher; leg is more active during cycling (requiring more O2) and gas exchange has already occurred in the capillaries
128
What happens to arterial O2 and mixed venous O2 concentrations as exercise intensity increases? Why?
Arterial O2 increases slightly due to hemoconcentration
Mixed venous O2 decreases due to more blood being diverted to metabolically active skeletal muscle.
129
What influences the a-vO2 difference?
*Metabolic activity of tissues
* Ability to divert blood to working muscles
* Capillary density
* Mitochondrial density/size/enzyme levels
* Time for O2 diffusion in the muscle (transit time of the blood through the muscle)
*Loading of O2 in the lung (altitude, pulmonary disease)
## Footnote
The a-vO2 difference reflects the metabolic activity of tissues.
130
If Mixed venous O2 content increases and arterial O2 content stays the same, what happens to: a-vO2 difference and VO2?
They both decrease
131
If Q stays the same but blood flow to exercising muscle increases, what happens to a-vO2 difference and VO2
They both increase
132
During cycle exercise, is the O2 content higher, lower or the same in the right atrium vs the femoral vein?
Higher in the right atrium and lower in the femoral vein
133
During cycle exercise, is the O2 content higher, lower or the same in the left atrium vs the femoral artery?
They are the same as blood has not reached the capillaries yet and no gas exchange has occured
134
What is the typical lung volume in a normal individual?
5 liters
135
What is the typical surface area of the lungs?
50-75 m^2
136
What factors influence lung volume? Which one is the most important?
Height - most important
Age
Sex
137
What happens to total lung volume with chronic exercise training?
Stays the same
138
What is TLC? Formula?
Total lung capacity
Formula - VC + RV
139
What is VC (FVC)
Vital Capacity (Forced Vital Capacity); the max capacity of a full inhale and full exhale
140
What is RV?
Residual volume left over after a full exhale
141
What is TV?
Tidal Volume; Volume of a normal breath
142
What is IRV?
Inspiratory Reserve Volume; volume left when you fill the lungs normally
143
What is ERV
Expiratory Reserve Volume; volume left after a normal expiration
144
What is FEV1?
Forced Expiratory Volume in 1s
Answers the question: How much of your vital capacity can you push out in one second?
145
What would a pulmonary clinician use FEV1 to diagnose?
Asthma
146
What is the relative percentage of FEV1 to diagnose asthma?
below 80% of FVC
147
What is MVV and its units? What is it a good approximation for?
Maximum Voluntary Ventilation (L/min)
Good approximation for capacity of maximal exercise ventilation
148
What is V_E? Formula?
Minute ventilation
Fb (breathing frequency) * TV
149
What is the conducting zone in the bronchi/bronchioles?
Zone where gas exchange does not occur, it is just conducted to further branches which do the exchange
150
How many generations of bronchioles are in the conducting zone? How big is it?
the first 16 generations
approx. 150 mL
151
How does air travel through the conducting zone vs past the terminal bronchioles of the lungs?
Conducting zone - bulk flow
Respiratory zone - diffusion
152
What is the primary reason for the efficacy of gas exchange in the lung?
Large surface area of lungs where alveoli come in contact with pulmonary capillaries
153
What are the pros and cons of the lungs having such thin capillaries and alveolar walls?
Pros: thin walls aid in diffusion (gas exchange), the walls are so thin RBC's are usually stacked with little empty space further aiding in gas exchange
Cons: Small change in pressure can lead to stress failures in the capillaries which could leak plasma, proteins, and sometimes RBC's into the alveolar space
154
Who is at risk for a "stress failure" in the capillary walls? Typically why does this happen?
Heart failure patients, athletes, and racehorses
Due to hypertrophy of right ventricle creating a higher pressure and thus potential break of capillary and leak into the lungs
155
What is boyles law?
P1 * V1 = P2 * V2
156
What are the three main pressures relative to the lung? What do they symbolize?
Barometric Pressure - Pressure of the atmosphere
Intrapulmonic Pressure - Pressure inside the lung
Intrapleural Pressure - Pressure in the thoracic cavity outside of the lung
157
What happens if intrapleural pressure is higher than intrapulmonic pressure
The lung would collapse
158
Are inspiration and expiration active or passive processes?
Inspiration - Always active
Expiration - Generally passive but can be active
159
Hyperpnea
When ventilation rises linearly in proportion to the increase in metabolic rate (VO2)
160
Hyperventilation
When ventilation increases disproportionately to the increases in metabolic rate
161
Ventilatory Threshold
– Workload or VO2 where ventilation increases disproportionately
162
What physiological variable does the ventilatory threshold generally correspond to?
Lactate Threshold
163
What is the reason for the ventilatory threshold occuring?
Increased lactic acid and thus H+ buildup which stimulates ventilation
164
What has a larger effect on V_E during exercise? Fb or TV?
At the start, TV
As exercise approaches max, Fb
165
Why does TV show a plateau at maximal exercise?
Due to decreased "filling time" of the lungs
166
In natural altitude vs simulated altitude even though there are physical differences, If PiO2 is the same, are there physiological differences?
As long as partial pressure of O2 is the same, the physiological response will be the same for the most part
167
what are the two types of transport for gasses in the body? Are they active or passive processes?
Bulk Flow - Active
Diffusion - Passive
168
What is the diffusion rate of a gas dependent on?
- Pressure Gradient (concentration) (IVP)
- Cross Sectional Area of tissue (DP)
- Solubility of the gas (DP)
- The distance the gas must diffuse (related to thickness) (IVP)
-The molecular weight of the gas (IVP)
169
Is O2 or CO2 more soluble?
CO2 by far
170
When is the only time it is possible for the lung to grow new tissue?
If a part of the lung or a lung is removed, the remaining tissue can grow to account for the lost tissue
171
What are the two forms that O2 can be transported?
Bound to Hb (98-99%)
Dissolved in plasma (1-2%)
172
What is the %Hb saturation dependent on?
PO2 of oxygen in blood
Blood Temperature
pH levels of the blood
2-3 DPG in the blood (product of glycolysis)
173
When does the oxyhemoglobin curve shift to the right? when does it shift to the left?
Right Shift - decrease pH, increased blood temperature, increase PCO2, increase in H+
Left shift - increase pH, decreased blood temperature, decrease H+, decrease in PCO2
174
What is the implication of the oxyhemoglobin curve shifting right vs left?
Right - Decreased saturation
Left - Increased saturation
175
How does a decline in a decline in PO2 affect the oxyhemoglobin curve?
Stays the same as long as H+ and temperature stay the same. It just moves along the curve since SaPO2 is on the x-axis and %concentration is on the y-axis.
176
- What are the physiological vs Psychological effect of breathing 100% oxygen
Physiological - very minimal increases in SaO2 and dissolved O2 in plasma (basically nothing)
Psychologial - Dyspnea
177
What is Dyspnea?
Reduced perceived effort of ventilation
178
Does O2 or CO have a higher affinity for Hb?
CO by far
179
Does fetal or adult hemoglobin have a higher affinity for O2?
Fetal, it will always outcompete the mother for O2
180
How long after birth does fetal Hb convert to adult Hb? What can this cause?
a few days to weeks; can cause Jaundice because the liver has to filter out the fetal hemoglobin
181
What are the three ways that CO2 can be transported in the blood?
Dissolved in plasma (10%)
Converting it to bicarbonate (60%)
Carbamino Compounds (30%) - bind to certain amino acids that are a part of the Hb protein
182
Does CO2 bind to the iron heme portion of Hb as O2 does?
NO, only O2 binds to those groups and the CO2 binds to carbamino compounds in Hb
183
What part of the brain is responsible for controlling the respiratory center?
The medulla
184
What does the respiratory center regulate?
Fb and TV
185
What are two subcomponents of the respiratory center?
Inspiratory center and Expiratory center
186
What three factors does the respiratory center respond to?
neural factors, chemical factors, and temperature
187
What are the neural factors that affect the respiratory center?
Sensory input from the mechanoreceptors/proprioceptors in the muscles and joints
Sensory input from stretch receptors in the lung
188
What are the chemical factors that affect respiratory center? What are they responsive to?
central chemoreceptors in brain- responsive to PCO2 and pH
Peripheral chemoreceptors in the carotid bodies and aortic bodies - responsive to PCO2, pH and PO2
Temperature - increase in body temp has a direct stimulating effect on the respiratory center
189
How does Muscular movement (exercise) affect ventilation in terms of the respiratory center
Mechanoreceptors stimulate the inspiratory center – the diaphragm and intercostal muscles contract to draw in large volumes of air into the lung
190
How does Stretching of the lung (hyperinflation) affect ventilation in terms of the respiratory center
Mechanoreceptors stimulate the expiratory center – the intercostal and abdominal muscles contract forcing air out of the lung
191
How does Increase in PCO2 / decrease in pH (as with exercise or disease) affect ventilation in terms of the respiratory center
Chemoreceptors (central and peripheral) stimulate the inspiratory center
192
How does Decrease in PO2 (as with altitude / disease) affect ventilation in terms of the respiratory center
Peripheral chemoreceptors stimulate the inspiratory center
193
How does Increase in temperature affect ventilation in terms of the respiratory center?
Directly stimulates the respiratory center to increase ventilation
194
What is the main function of the respiratory center?
To tightly control arterial PCO2 and blood pH and arterial PO2 being a "MINOR" consideration
195
T/F - we breathe more to get more oxygen into the blood?
False unless at altitude or pulmonary disease state
196
alkalosis
pH > 7.4
197
Acidosis
pH < 7.4
198
What is the lowest arterial pH the body can tolerate (for a short period of time)?
6.9
199
The pH of the blood and other body fluids is regulated by...
chemical buffers
Ventilation
The kidneys
200
What are the main chemical buffers in the body?
bicarbonate, Hb (and other proteins), phosphates
201
What is the mechanism of the ventilatory buffer on regulating pH?
As V_E increases, (blowing off CO2) H+ ions decrease and pH increases
202
Which buffer system is the most effective in regulating pH? chemical or ventilatory?
Ventilatory buffer is about twice that of all the chemical buffers combined
203
What is the mechanism of the kidney buffer in regulating pH? What is the issue with the kidney buffer?
They can excrete or retain H+ or HCO3- (bicarbonate) ions to regulate pH.
It is more time consuming
204
What is ventilation regulated by largely at rest?
Arterial PCO2 as small increases cause a large increase in V_E
Arterial PCO2 is VERY tightly regulated
205
What are the two phases of ventilation control during exercise?
Phase 1 - initial rapid increase in V_E due to neural response to muscular movement; begins before the onset of exercise (anticipatory response)
Phase 2 - A gradual increase in VE produced by response to chemical and temperature changes
206
What is ventilatory drive controlled by at altitude?
peripheral chemoreceptors located in the carotid bodies of the neck
207
What is HVR?
Hypoxic Ventilatory Response; how VE changes with SaO2 changes
208
How does a high HVR affect performance at altitude?
Maintains PO2 to hold O2 delivery
Increased perception of ventilatory effort
209
What is a reason for endurance athletes having a low HVR?
Could be advantageous at sea level as they tend to breathe less and expend less energy doing so than normal individuals
210
What determines if a person has a high or low HVR
LARGELY by genetics
there are some individual cases where it can be improved with chronic training but generally it is just genes
