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99 Cards in this Set

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Where are discontinuous capillaries often found?
sinusoids of liver, spleen, and bone marrow
What characteristics of capillaries make them ideal for rapid diffusive exchange?
-extreme proximity to cells
-large surface/volume ratio
-low flow velocity
-thin walls
What metabolites can undergo transcellular transcapillary exchange?
small nonpolar molecules:
-O2
-CO2
What metabolites can pass through intercellular clefts in transcapillary exchange?
-K+
-glucose
-Na+
-Cl-
What are the 3 mechanisms that can increase transcapillary exchange?
-capillary recruitment
-increased tissue concentration gradients
-increased blood flow
For what types of solutes will increased blood flow cause increased transcapillary exchange?
small nonpolar molecules which cross capillary walls easily (e.g. O2)
What is Starling's principle of fluid exchange?
-fluid filtration = k[(Pc - Pi) - (πc - πi)]
-fluid filtration = hydraulic drive - osmotic suction
What 4 parameters influence Pc most strongly?
-distance along capillary
-arterial and venous pressures
-gravity
-sympathetic vasomotor tone
How does arteriolar dilation affect fluid filtration in the capillaries?
filtration becomes more prominent than absorption because hydraulic pressure increases
How does arteriolar constriction affect fluid filtration in the capillaries?
absorption becomes more prominent than filtration because hydraulic pressure decreases
What are the 4 types of edema?
-inflammatory edema (increased permeability of endothelium)
-venous edema (increased venous pressure)
-hypoproteinemic edema (decreased plasma proteins)
-lymphatic edema (lymphatic obstruction)
What type of heart failure causes systemic edema?
right heart failure
What type of heart failure causes pulmonary edema?
left heart failure
What are the functions of the lymphatic system?
-returns excess interstitial fluid to the blood
-returns interstitial protein to the blood
-transports cells (immune)
-transports large molecules and debris
What factors contribute to circulation of lymph fluid?
-pressure gradients
-one way valves
-smooth muscle cells encircling lymphatics
What is filariasis?
The parasitic worm Wuchereria bancroft forms nests in the lymphatic system, causing blockages. This results in edema.
What does a p-value in statistical analysis indicate?
large p-values in a comparison of two groups indicate that there is no difference between the two groups
What is the difference between intent-to-treat analysis and treatment-received analysis?
-intent-to-treat: analysis is done assuming that all subjects received their assigned treatment
-treatment-received: results are analyzed using the actual treatment received by the patient
What aspects of a treatment are best measured using treatment-received analysis?
-efficacy of treatment
-analyzes therapy under ideal conditions
What aspects of a treatment are best measured using intent-to-treat analysis?
-effectiveness of treatment
-analyzes therapy under real-life conditions
What is a double blind study?
the following parties do not know what treatment group a subject has been assigned:
-subject
-personnel administering the treatment
-personnel assessing the outcomes/endpoints
What is a triple blind study?
the following parties do not know what treatment group a subject has been assigned:
-subject
-personnel administering the treatment
-personnel assessing the outcomes/endpoints
-personnel analyzing the study (statistician)
What is a Type I/α-error in statistical analysis? How is it identified?
-the result being due to chance
-present when the p-values are > 0.001
What is a Type II/β-error in statistical analysis?
sample size is too small to detect true differences
What are the types of pleurae that encase the lungs?
-visceral (inner) pleura
-parietal (outer) pleura:
cervical
costal
diaphragmatic
mediastinal
How does the innervation of visceral and parietal pleura differ?
-visceral: supplied by autonomic nervous system (no pain)
-parietal: supplied by somatic nervous system (pain) → intercostal and phrenic nerves
What part of the parietal pleura is supplied by the intercostal nerves?
costal
What parts of the parietal pleura are supplied by the phrenic nerves?
-diaphragmatic
-mediastinal
What is pneumothorax? What causes it?
-collapse of the lung and separation of the two pleurae
-caused by introduction of air into pleural cavity
What is tension pneumothorax?
pressure increase in the pleural cavity with a punctured lung causes mediastinal contents to be shifted to the other side, applying pressure to it
Where is the apex of the lung with respect to the ribs?
above the level of the 1st rib
Where do the oblique fissures begin and end with respect to the lungs and ribs?
-begin at the posterior medial edge of the lung at the level of the base of the scapular spine
-end at the inferior border of the lung at costochondral junction of the 6th rib
The horizontal fissure meets the anterior border of the right lung at the level of which rib?
rib 4
The midclavicular line intersects the bottom of the lung at the level of which rib?
rib 6
The midaxillary line intersects the bottom of the lung at the level of which rib?
rib 8
The scapular line intersects the bottom of the lung at the level of which rib?
rib 10
The midclavicular line intersects the bottom of the parietal pleura at the level of which rib?
rib 8
The midaxillary line intersects the bottom of the parietal pleura at the level of which rib?
rib 10
The scapular line intersects the bottom of the parietal pleura at the level of which rib?
rib 12
How would injury to the phrenic nerve affect breathing?
The affected side of the diaphragm would be paralyzed.
How does the shape of the thoracic cage change with deep breathing?
-upper ribs: increase the anteroposterior dimension
-lower ribs: increase the transverse dimension
What grooves/impressions are present in the left lung and not in the right?
-brachiocephalic vein groove
-aortic impression
-cardiac notch
Where is the trachea with respect to the esophagus? Where does it bifurcate with respect to the spinal cord?
-the trachea is anterior to the esophagus
-it bifurcates at the level of T4-T5
From what structure do the pulmonary arteries arise? What is their purpose?
-pulmonary tract
-convey poorly oxygenated blood to the lungs
What is the mean pulmonary arterial pressure?
15 mmHg
Into what structure do pulmonary veins drain? What is their function?
-left atrium
-convey well oxygenated blood from the lungs
From what structures do bronchial arteries arise? What is their function?
-thoracic aorta
-posterior intercostal arteries (right)
-right bronchial artery may arise from the left
-carry well oxygenated blood to supply walls of bronchi and pleura
Into what structure do bronchial veins drain? What is their function?
-azygos vein (right)
-accessory hemiazygos vein (left)
-carry poorly oxygenated blood from the lungs
What is the superficial (subpleural) lymphatic plexus? To where does it drain?
-drains the surface of visceral pleura
-drains to bronchopulmonary (hilar) nodes
What is the deep lymphatic plexus? To where does it drain?
-follows the bronchi and pulmonary vessels
-drains to bronchopulmonary (hilar) nodes
What are the tracheobronchial lymph nodes? To where do they drain?
-drain the bronchopulmonary (hilar) lymph nodes
-drain into paratracheal nodes
To where do paratracheal lymph nodes drain?
-bronchomediastinal trunk → subclavian veins
-thoracic duct (left side)
Which pulmonary lobes are drained by the left paratracheal lymph nodes? Which are drained by the right?
-left: drain left superior lobe
-right: drain right lung, left inferior lobe
What is the effect of efferent vagal stimulation on the lungs?
bronchoconstriction
What is the effect of afferent vagal stimulation on the lungs?
-cough reflex
-stretch reception
-vasodilation
What is the effect of efferent sympathetic stimulation on the lungs?
-bronchodilation
-vasoconstriction
What is the effect of afferent sympathetic stimulation on the lungs?
none
Which ganglia supply the lungs with sympathetic stimulation?
upper four thoracic ganglia
What is the pulmonary edema safety factor?
pressure difference between the capillaries and alveoli assures that absorption > filtration along the length of the pulmonary capillaries → water is always absorbed from the lung
What effect do inotropic drugs have on left ventricle performance?
increase stroke volume and cardiac output
What effect do vasodilators have on left ventricle performance?
-decrease left ventricle end-diastolic pressure
-increase stroke volume and cardiac output
What effect do diuretics have on left ventricle performance?
decrease left ventricle end-diastolic pressure
What is the difference between vascular response to hypoxia in the systemic tissues vs. the lungs?
-systemic tissues: hypoxia/ischemia → vasodilation
-lungs: hypoxia → vasoconstriction
What is the sequence of events that occur with High Altitude Pulmonary Edema?
-pulmonary hypoxic vasoconstriction
-pulmonary hypertension
-pulmonary edema
-impaired gas exchange
-positive feedback loop
What is the foramen ovale? What happens to it following birth?
-shunt which allows highly oxygenated blood to enter the left atrium from the right atrium
-often sealed in the first year following birth as a result of left atrium pressure rising above right atrium pressure
What is the ductus arteriosus? What happens to it following birth?
-shunt which allows blood to enter the aorta from the right ventricle
-"functional closure" in 1-8 days following birth due to pulmonary artery pressure dropping below aortic pressure
-"anatomical closure" in 1-4 months following birth
What is Patent Ductus Arteriosus?
-failure of the ductus arteriosus to seal
-leads to pulmonary hypertension
How do systemic vascular resistance and arterial pressure change with birth? Why?
2-fold increase, due to increase in blood flow from the lungs to left ventricle
How does pulmonary vascular resistance change with birth? Why?
10-fold decrease, caused by inflation of lungs and removal of fluid by coughing
What is the ductus venosus?
-connects umbilical vein to the inferior vena cava
-carries highly oxygenated blood
-allows bypass of the fetal liver
How do the right and left ventricles change following birth? What is the electrical manifestation of this change?
-right ventricle atrophies
-left ventricle hypertrophies
-electrical axis of the heart swings to the left
Does gravity have a greater effect on venous or arterial pressure? Why?
-venous pressure
-because the veins are distensible
What is the effect of arising on mean arterial pressure and central venous pressure?
small transient decrease (due to gravity)
What is the effect of arising on heart rate?
30% increase (as compensation)
What is the effect of arising on stroke volume?
40% decrease (Frank-Starling mechanism)
What is the effect of arising on cardiac output?
25% decrease (combination of changes in heart rate and stroke volume)
What is the effect of arising on systemic vascular resistance?
increases (as compensation)
What is the effect of arising on splanchnic, renal, and leg flow?
25% decrease (as compensation)
What is the effect of arising on venous tone?
increases (as compensation)
What is the effect of arising on central blood volume?
400 mL decrease
What is the effect of arising on blood volume in legs?
600 mL increase
What is the cause of the increase in heart rate to 100 beats/min in response to exercise?
withdrawal of vagal tone
What is the cause of the increase in heart rate to 100-200 beats/min in response to exercise?
sympathetic augmentation
Why are athletes able to perform relatively more exercise at a given heart rate?
larger stroke volume
Why does arterial pressure remain relatively stable during exercise, in comparison with cardiac output increase?
systemic vascular resistance decreases with exercise
What is the sequence of events that leads to cardiogenic shock?
-myocardial failure
- ↓cardiac output
- ↓arterial pressure
What is the sequence of events that leads to hemorrhagic shock?
-blood loss
- ↓central venous pressure
- ↓cardiac output
- ↓arterial pressure
What is the sequence of events that leads to anaphylactic (septic) shock?
-vasodilator release
- ↓systemic vascular resistance
- ↓arterial pressure
What is the sequence of events that leads to neurogenic shock?
- ↓sympathetic drive
- ↓systemic vascular resistance
- ↓arterial pressure
How does the brain respond to shock (short-term)?
-cerebral ischemic response (below 60 mmHg)
- ↓parasympathetic activity
- ↑sympathetic activity
How does the heart respond to shock (short-term)?
- ↑heart rate
- ↑contractility
- ↑cardiac output
How does the vasculature respond to shock (short-term)?
- ↑vaso/venoconstriction
- ↑systemic vascular resistance
- ↓capillary pressure → transcapillary fluid absorption
How are the kidneys affected by shock?
-sympathetic augmentation (from brainstem)
- ↓renal perfusion (from ↓systemic vascular resistance)
How do the kidneys respond to shock (long-term)?
-RAA pathway
- ↓glomerular filtration
- ↓urine output
- ↑thirst
- ↑central venous pressure
How long can the brain and heart be deprived of blood flow before experiencing irreversible ischemic damage?
2-5 min
How long can the kidney, lungs, and liver be deprived of blood flow before experiencing irreversible ischemic damage?
120-180 min
How long can the skeletal muscle, gut, and skin be deprived of blood flow before experiencing irreversible ischemic damage?
360-600 min
By what mechanisms is blood volume restored after hemorrhage?
-transcapillary refill
-renal fluid conservation
-thirst + sodium appetite
What are the decompensatory mechanisms in shock?
-intense sympathetic vasoconstriction
-ischemia of organs
-metabolic vasodilators override sympathetic input
- ↓mean arterial pressure
-positive feedback loop