E1 Flashcards
(209 cards)
1
Q
What is PGC-1 alpha?
A
Key regulator of the body’s response to exercise
2
Q
What are the systemic effects of PGC-1 alpha?
A
Skeletal muscle hypertrophy, hyperplasia, fiber type switching
3
Q
What are the cardiac effects of PGC-1 alpha?
A
Metabolism for oxidative phosphorylation and mitochondrial biogenesis
4
Q
How do you measure maximal oxygen consumption during exercise?
A
Measure VO2 max
5
Q
What percentage of cardiac output is delivered to skeletal muscle during exercise?
A
85-90%
6
Q
At peak exercise, what is the ventilation rate?
A
15-25x the starting rate
7
Q
How does the body reach steady-state conditions during exercise?
A
Progressive increase in heart rate with decrease in stroke volume and mean arterial pressure
8
Q
How does skeletal muscle adapt to heavy resistance training?
A
Training activates Type IIX fibers and many will change from IIX to IIA
9
Q
How does hypertrophy affect whole muscle growth?
A
Increased protein synthesis and reduced breakdown
10
Q
How do you calculate VO2 max?
A
Q x (a - VO2 difference)
Flow x Arteriovenous O2 difference
11
Q
What is a normal expiration volume compared to VO2 during exercise?
A
40-50%
12
Q
What are the weekly recommendations for physical activity for someone with minimal/moderate physical activity level?
A
30 min x 5 days of moderate intensity
or
25 min x 3 days of vigorous intensity
13
Q
What are the weekly recommendations for physical activity for someone with optimal/high physical activity level?
A
60 min x 5 days of moderate intensity
or
30 min x 5 days of vigorous intensity
14
Q
What are the three major components of the Exercise is Medicine initiative?
A
Assess physical activity
Provide counseling
Provide tools for self-management of exercise
15
Q
Identify factors that are likely to increase the likelihood of a positive physical activity behavior change
A
5 As:
- Ask about physical activity status
- Advise about specific recommendations related to the patient to become more active
- Agree upon specific physical activity goals
- Assist with making an action plan or refer to resources
- Arrange for a follow-up contact within a few weeks
16
Q
What is flux?
A
Hydraulic conductivity x [outward driving forces - inward driving forces
17
Q
What is the equation for flux?
A
Flux = Resistance x [(Hydrostatic force + Interstitial oncotic pressure) - (Rebasorption force + interstitial hydrostatic pressure)]
18
Q
What is normal capillary hydrostatic force (Pc)?
A
17.3 mmHg
19
Q
What is normal interstitial oncotic pressure?
A
8 mmHg
20
Q
What is normal capillary oncotic pressure?
A
28 mmHg
21
Q
What is intersitital hydrostatic pressure?
A
-3 mmHg
22
Q
Reabsorptive force is directly related to….
A
Protein concentration in the blood
23
Q
Why can liver disease result in edema?
A
Reduced production of plasma proteins in the liver
24
Q
Why can obstruction of venous circulation result in edema?
A
Because of increased capillary pressure resulting from the resistance to flow
25
What is the cause of edema associated with infection?
Blockage of lymphatic drainage preventing removal of extra interstitial fluid
26
How can allergic reactions or capillary trauma cause edema?
By increasing capillary permeability (Kf) and thus allowing plasma proteins to leak into the interstitial space (increasing interstitial oncotic pressure)
27
How are capillary beds arranged and why?
They are arranged in parallel, rather than series, so that changing flow to one organ does not affect other organs.
28
What two factors determine blood pressure?
Volume and vessel
29
What's more compliant--arteries or veins?
Veins are 20x more compliant because they store most of the body's blood
30
What kind of buffers are arteries and veins?
Arteries: pressure
Veins: volume
31
How does vascular compliance change with age?
Compliance lost w/ age --> Stiffening arteries --> Lost diastolic pressure
32
What must be maintained to ensure capillary perfusion?
MAP
33
What determines preload and afterload?
Pre: EDV
After: Aortic Pressure or Pulmonary Artery Pressure
34
What is an index of systolic function?
Ejection fraction
35
What three factors modulate stroke volume?
SV CAP: Contractility (+), preload (+), afterload (-)
36
What is Starling's Law?
The greater the preload, the greater the afterload
37
What is S1?
Mitral and tricuspid
38
What is S3?
Common extra heart sound
Indicates increased ventricular filling
Usually due to CHF
39
What is mitral regurgitation?
When blood flows back into the left atrium from the LV
40
What is aortic stenosis?
When blood flows through tight aortic valve into ascending aorta
41
Where is aortic stenosis best heard on auscultation?
R 2nd interspace, radiates into both carotids
42
What is the law of LaPlace?
Distended ventricles decreases developed pressure
Wall stress = Pr / 2*wall thickness
43
What is the equation for cardiac work?
W = Aortic pressure x SV
44
Which drugs lower preload? Afterload?
PrEload : vEnodilators
| Afterload : vAsodilators
45
How do venodilators work?
By changing vessel radius: dilated veins cause blood to pool in the periphery --> decreased venous return to heart --> ventricular radius gets smaller --> heart becomes more efficient
46
Why do we give diuretics for CHF?
Diuretics decrease total blood volume, and therefore venous return.
47
What is the relationship between systolic interval and contractility?
Inverse
48
What mainly affects systolic and diastolic intervals?
Systolic: contractility
Diastolic: HR
49
What is mean systemic pressure?
6.5 mmHg
50
How does adenosine affect vasculature?
Vasodilator
Increased tissue activity degrades ATP to adenosine
Hypoxia depresses ATP formation, adenosine accumulates
51
How does potassium affect vasculature?
Vasodilator
Small amounts accumulate in extracellular space when released during muscle contraction
These small amounts hyperpolarize VSM
52
How does CO2 affect vasculature?
Diffuses into VSM to cause vasodilation
Combines with H2O to release H+
H+ vasodilates by repolarizing VSM potassium channels
53
What is hyperemia?
Increased blood flow due to vasodilation
54
How does autoregulation work?
It changes resistance to keep flow constant despite changing perfusion pressures
55
How does nitric oxide affect vasculature?
Diffuses rapidly into VSM
| Activates soluble guanylate cyclase --> converts GTP to cGMP
56
How is nitric oxide synthesized?
From L-arginine by NOS
57
What is cGMP?
Powerful vasodilatory 2nd messenger
58
How does increased flow affect nitric oxide production?
Increases it. Flow causes shear stress on endothelium, which releases NOS
59
How does prostacyclin affect vasculature?
Powerful vasodilator
| Stimulates adenylate cyclase activity --> produces cAMP
60
Which vasodilator is derived from arachidonic acid?
Prostacyclin
61
Which endothelial factor inhibits platelet aggregation?
Prostacyclin
62
How does calcium affect myocytes?
Myocyte contraction is calcium-dependent:
Extracellular calcium enters through L-type Ca2+ channel
Binds to ryanodine receptor on sarcoplasmic reticulum, which releases more calcium
63
What is SERCA?
Pumps Ca2+ back into SR using ATPase
64
What provides the brakes for the SERCA pump?
Phospholamban
65
How does norepinephrine affect myocytes?
Increases contractility by increasing calcium
1. Stimulates beta-1 receptors, which increase cAMP. cAMP stimulates PKA, which activates Ca2+ channels through phosphorylation
2. NE also stimulates relaxation -- PKA deactivates phospholamban through phosphorylation
66
What is the resting polarization of cardiac cells?
-90 mV
67
What can EKGs tell us?
```
Impulse initiation/propagation
HR and position
Heart rhythm and conduction
Chamber size
Infarction
```
68
What can EKGs NOT tell us?
Contractility
Relaxation
EF, pressure, and flow measurements
69
What is an EKG lead?
Time course of voltage change between two electrodes
70
P wave
Atrial depolarization
71
Q wave
Typically seen in MIs, especially recent MIs
72
R wave
Ventricular depolarization
73
S wave
End of ventricular depolarization
74
T wave
Ventricular repolarization
75
What do inverted T waves indicate?
Recent MI
76
How long should PR interval be?
Less than 0.2 seconds (one big box)
77
How do you calculate rate from an EKG?
300 / boxes in R-R interval
78
What do regular, prolonged PR intervals indicate?
1st degree AV block
79
What do progressively lengthening PR intervals followed by a drop beat indicate?
2nd degree AV block, type I (Wenckebach)
80
Dropped beats that are not preceded by a change in the length of the PR interval indicate _______
2nd degree AV block, type II
81
What is indicated when atria and ventricles beat independently of each other?
3rd degree AV block (Both P waves and QRS complexes are present, although the P waves bear no relation to the QRS complexes)
82
What is atrial natriuretic peptide?
Released from atrial myocytes in response to increased blood volume and atrial pressure. Acts via cGMP. Causes vasodilation and decreased Na+ reabsorption at the renal collecting tubule.
83
What is B-type natriuretic peptide?
Released from ventricular myocytes in response to increased tension. Similar physiologic action to ANP, with longer half-life.
84
What is indicated by prolonged QRS complex with shortened PR interval?
Wolf-Parkinson-White (hallmark = delta waves)
85
How is Wolf-Parkinson-White treated?
With ablation
86
How do RVH and LVH present on EKG?
RVH: large R in anterior precordials
LVH: large R in lateral precordials
87
What are the lateral leads?
I, aVL, V5, V6
88
What are the inferior leads?
II, III, aVF
89
What are the anterior/septal leads?
V1-4
90
Which electrodes are at the left arm?
Positive and negative
91
Which electrodes are at the right arm?
Both negative
92
Which electrodes are at the foot?
Both positive
93
What is the composition of air?
21% O2
| 79% N
94
What determines flow?
Pressure
95
Where in the pulmonary system does flow have the highest velocity?
Medium bronchi (lowest cross-sectional area, highest velocity)
96
What clears the majority of deposited particles? What does it consist of?
Mucociliary transport system (99%)
| Three layers: cilia, sol, gel
97
Cilia beat toward the _____
pharynx
98
What secretes the sol layer?
Pseudostratified columnar epithelium
99
What secretes the gel layer?
Goblet cells, Clara cells, submucosal glands
100
Why do smokers have chronic lower respiratory infections?
Because smoke impairs macrophages
101
How do alveolar macrophages work?
They contain lysozymes, which engulf particles. They are able to migrate to smaller airways.
102
What has the biggest influence on resistance?
Radius (Poiseuille's law)
103
What is Ohm's law?
V=IR --> Flow = Pressure change / Resistance
104
If r decreases by 1/2, R _____ by _______
Increases / 16
105
Where is the highest resistance in the pulmonary system?
Medium sized bronchi (also has lowest cross-sectional area and highest flow velocity)
106
T/F: alveolar ducts and sacs are smooth muscle
False
107
Albuterol mechanism of action
Beta-2 agonist --> vasodilation
108
Which receptors are involved in sympathetic dilation of airway smooth muscle?
Beta-2
109
How do increased PCO2 and decreased PO2 affect airway smooth muscle?
Airway dilation, decreased resistance
110
What is the slope of the P-V curve?
Compliance
111
What is normal pulmonary compliance?
200 mL/cm H2O
112
How does COPD affect lung walls?
Destroys them by increasing compliance, decreasing elasticity, and increasing resistance
113
COPD is most obvious during inspiration or expiration?
Expiration --> prolonged as the patient forces air out through obstructed airways
114
How does fibrosis affect the pulmonary system?
Thickens alveolar walls by increasing oxygen, increasing elasticity, and decreasing compliance
115
How does surface tension affect compliance? How does surfactant affect surface tension?
Decreases
116
Which cells secrete surfactant?
Alveolar type II cells
117
When does surfactant form?
During weeks 24-35 of gestation
118
What is hysteresis?
Difference in P-V curves (compliance) between inspiration and expiration
119
Hysteresis is due to _____ and reduced by _______
Surface tension / surfactant
120
2 x surface tension / alveolar radius = _______
Pressure
121
What is intrapleural pressure?
Pressure in pleural space --> typically negative --> holds lungs open
122
What is transpulmonary pressure?
Difference between alveolar pressure and intrapleural pressure
123
What is the transpulmonary pressure during inspiration?
High
124
How does pneumothorax affect ventilation?
Air enters intrapleural space, destroys pressure gradient --> lung cannot expand, collapses instead
125
What is tidal volume?
500 mL -- air moving into lung during quiet inspiration
126
Additional air inhaled after tidal volume
Inspiratory reserve volume
127
Air breathed out after normal expiration
Expiratory reserve volume
128
Air that cannot be breathed out
Residual volume
129
IRV + TV =
Inspiratory capacity
130
RV + ERV =
Functional residual capacity
131
TV + IRV + ERV =
Vital capacity
132
IRV +TV + ERV + RV =
Total lung capacity
133
What cannot be measured by spirometry?
RV, FRC, TLC
134
What are the muscles of inspiration?
```
DIAPHRAGM
External intercostals
SCM
Anterior serratus
Scalenes
```
135
What are the muscles of expiration?
ABDOMINALS
| Internal intercostals
136
What provides long-term blood pressure regulation?
Kidneys
137
What provides acute blood pressure regulation?
Nervous system
138
Sympathetic neurotransmitter
NE
| Epi
139
Parasympathetic neurotransmitter
Acetylcholine
140
How does acetylcholine affect vasculature?
Endothelium-dependent vasodilator (releases NOS)
141
Sympathetic receptors
Andrenergic:
Alpha-1 : vessels
Beta-1 : heart
142
Parasympathetic receptors
Cholinergic:
| Muscarinic (M-2) : heart
143
Arterial contraction increases ______
TPR
144
Venous contraction increases ______
VR (and CO)
145
How do beta receptors affect contractility?
Increase. Beta receptors increase cAMP, activate PKA, and open Ca2+ channels
146
How do parasympathetics stimulate blood vessels?
There is no parasympathetic stimulation of blood vessels
147
What is a potential side effect of beta blockers?
Orthostatic hypotension
148
What is the baroreceptor reflex?
Increased pressure = increased stretch = increased firing
149
Where are baroreceptors located?
High pressure areas: aortic arch, carotid sinus
150
How does hypertension affect baroreceptors?
BRs lose sensitivity if BP is constantly high and are therefore less effective at buffering acute BP changes
151
How do baroreceptors affect vasculature?
Decreased blood pressure = decreased BR stretch, so BRs DON'T fire. ANS is activated, sympathetics stimulated and parasympathetics inhibited.
SNS: increased HR and contractility
PNS: increased HR (because parasympathetic system is inhibited)
152
Where are cardiopulmonary stretch receptors located?
Low pressure areas: atria, pulmonary arteries
153
How do cardiopulmonary stretch receptors work?
They sense increased blood volume by measuring filling pressure.
154
What is the Bainbridge reflex?
If P increases, HR will increase due to atrial pressure
155
What is the renal response to atrial volume?
Reduces fluid levels
- -Decreased ADH secretion (enhanced fluid excretion)
- -Dilation of renal arteries
- -Release of ANP (promotes Na+ excretion and therefore fluid excretion)
156
What is the Cushing reflex?
Increased intracranial P increases MAP
| Must have MAP>P(IC) for perfusion of the brain
157
The Cushing reflex can trigger _______
bradycardia
158
Acute HTN + Bradycardia =
Brain injury
159
What is physiologic dead space?
The amount of alveolar tissue capable of participating in gas exchange but unable to because of some physical factor (e.g. lack of blood flow to a region of the lung)
160
What is anatomical deadspace?
The portion of the airway that conducts air to the alveoli but cannot participate in gas exchange due to its specific anatomy (e.g. trachea, main bronchi).
161
Which circulation supplies the lung parenchyma?
Bronchial
162
What are the three hallmarks of pulmonary circulation?
1. Low pressure / Low resistance
2. High capacity
3. Vasoconstriction in response to hypoxia
163
What are the functions of pulmonary circulation?
Gas exchange in pulmonary capillaries
Vasoconstriction (ACE)
Filter
Blood reservoir
164
Where is ACE present in the pulmonary system and what does it do?
Present in endothelial cells in pulmonary capillary beds
| Converts angiotensin I to angiotensin II
165
What is PVR?
PVR = pulmonary vascular resistance = pressure gradient
166
PVR =
(Pulm artery pressure - Left atrial pressure) / CO
167
What is normal pulmonary blood pressure?
25/8
| artery/capillaries
168
What is pulmonary wedge pressure used for?
Estimating LA pressure
| Used to assess pulmonary capillary pressure in CHF
169
How do flow and pressure distribute in an upright lung?
From top to bottom, P increases, so flow also increases
170
Pressure in lung above and below heart
Above: 15 mmHg
Below: 8 mmHg
171
What features of the pulmonary system increase its blood capacity?
Thin wall and larger diameter
172
What is the pulmonary system's circulatory response to hypoxia?
Vasoconstriction: low alveolar O2 --> constriction of adjacent vessels
This is to preserve blood for pulm circulation -- blood must be ventilated for the body to use
173
What determines the ability of respiratory membrane to transport a gas in/out of blood?
Diffusion capacity
174
How does edema affect diffusion rate?
Liquid accumulation affects d (distance/thickness)
175
How dos COPD affect diffusion?
Decreases diffusion because of decreased surface area of alveoli
176
What is vapor pressure?
Partial pressure of H2O in inhaled air
| 47 mmHg
177
What does vapor pressure depend on?
Only on body temperature
178
How is vapor pressure used to calculate partial pressure?
PO2 = (760 - 47) x 0.21 = 150 mmHg
179
How is O2 transported in the body?
Hemoglobin (97%)
| Dissolving (3%)
180
What is P50?
PO2 at 50% hemoglobin saturation
181
What causes a right shift in the O2 dissociation curve?
ACE BATs right-handed:
```
Acid
CO2
Exercise
BPG
Altitude
Temperature
```
182
Bicarb equation
CO2 + H2O --> H2CO3 --> H+ + HCO3-
183
Enzyme used to create bicarb
Carbonic anhydrase
184
What is the Haldane effect?
PO2 increase --> Right shift of CO2 curve
185
What is the Bohr effect?
PCO2 increase --> Right shift of O2 curve
186
PCO2 increase causes pH ______
Decrease
187
What is normal ventilation perfusion ratio?
V(A) / Q = 4.2/5 = 0.8
188
Ventilation perfusion ratio difference between upper and lower lung
Upper: > 0.8 (more physiologic dead space)
Lower: < 0.8 (more flow, less air)
189
What is the Alveolar-arterial oxygen gradient?
P(AO2) - P(aO2) = 5-15 mmHg
190
What causes the Alveolar-arterial gradient?
Bronchial circulation
| Imperfect perfusion ratio
191
What is arterial pressure in hypoxemia?
< 85 mmHg
192
A-a gradient is normal in _____ and ______
High altitude / hypoventilation
193
Arterial PO2 set point
100 mmHg
194
PCO2 set point
40 mmHg
195
pH set point
7.4
196
What controls inspiration and basic ventilation rhythm?
Dorsal respiratory group in the medulla
197
What controls expiration?
Ventral respiratory group in the medulla
198
What is the pneumotaxic center?
Inhibits DRG
Regulates respiratory rate and volume
Located in the medulla
199
Where are central chemoreceptors located?
Ventral medulla (not part of respiratory control center)
200
What stimulates central chemoreceptors?
Increased H+
Sensitive to PCO2 change in blood. CO2 is able to cross BBB, so it combines with H2O, becomes bicarb, diffuses across BBB, and dissociates into H+
201
What is the most important stimulus of respiratory control centers?
Increased arterial PCO2
| Major response is in central chemoreceptors, but faster response is in peripheral chemoreceptors
202
What magnifies respiratory response to increased arterial PCO2?
Decreased arterial PO2
203
Which respiratory stimulus is important in high altitude / long-term hypoxemia?
Decreased arterial PO2
204
What is hypoxemia?
Low oxygen in blood
205
Peripheral chemoreceptors are stimulated by ______
Decreased arterial pH
206
How does air composition change at high altitude?
It doesn't
207
What are important pressures at sea level?
Barometric pressure: 760 mmHg
PH2O (vapor pressure): 47 mmHg
PO2: 150 mmHg
PN2: 563 mmHg
208
How does vapor pressure change with altitude?
Does not change in healthy individuals
209
What is the body's response to high altitudes?
```
Rapid response: hyperventilation
PCO2 decreases
Respiratory alkalosis
Renal compensation in 1-2 days
Acclimitization
```
