KEY NOTES WK 4 lec 3

Question 1

gas exhange is determined by

Answer 1

partial pressure gradient across the alveolar–capillary membrane.

Question 2

oxygen transported in systemic circulation bound to

Answer 2

hemoglobin = oxyhemoglobin

Question 3

gas transfer in lungs affected by

Answer 3

(uptake of O2 and the unloading of CO2) are affected primarily by blood flow.

Question 4

pulmonary vs systemic circulation

Answer 4

pulmonary gets all cardiac output

Question 5

pulmonary circulation

Answer 5

superior and inferior vena cava to alveoli for gas exhange

Question 6

pulmonary circulation functions

Answer 6

1. it serves as a filter (trap thrombi and emboli, has fibrinolytic substances)
2. a metabolic organ (angiotensin II for vasoconstriction, bradykinin, serotonin, prostaglandin, If acute injury release histamine and prostaglandins)
3. a blood reservoir. (10% of blood volume, mobilize blood to improve cardiac output if hemorrhagic shock)

Question 7

conducting airways and bronchial circulation

Answer 7

The bronchial circulation is responsible for supplying oxygen and nutrients to the lung tissue itself (the bronchi, bronchioles, and pleura)—it does not participate in gas exchange.

Question 8

what can undergo angiogenesis

Answer 8

bronchial circulation

i.e. make collateral circulation if clot or embolus

Question 9

flow, pressure and resistnace in pulmonary circulation

Answer 9

Unlike the systemic circulation, the pulmonary circulation is a high flow, low-pressure and low- resistance system.

pulmonary artery has thinner wall, less elastin and smooth muscle that aorta = more compliant

pulmonary arterioles less ability to constrict than systemic

Question 10

pulmonary vs systemic circulation: dilated and constricted

Answer 10

pulmonary= dilated

systemic= constricted

Question 11

Pulmonary Capillary Wedge Pressure:
 Swan Ganz Catheter


Answer 11

direct measurement of pulmonary artery pressures and indirect measurement of left heart pressures

Question 12

pulmonary vascular resistnace is low to reduce workload of

Answer 12

right ventricle

Question 13

pulmonary vascular resistance decreases with

Answer 13

increased cardiac output

DIF FROM SYSTEMIC where an increase in perfusion pressure increases vascular resistance.

Question 14

how pulmonary vascular resistance decreases with increased cardiac ouput

Answer 14

1. recruit capillaries
2. distend capillaries (widen)

Question 15

enhancing gas exchange in lungs with higher cardiac output benefits

Answer 15

adequate time to uptake oxygen and get rid of CO2 (no increase in capillary blood flow)

increase capillary surface area to help gas exhange

Question 16

when cardiac output increases but resistance doesnt what can it protect from

Answer 16

lung edema (bc low pressure)

pulmonary edema if high pressure (fluid accumulate in alveoli)

Question 17

pulmonary vascular resistnace is optimal around _____

resistance increases at ______

Answer 17

optimal = functional residual capacity

more resistant at high (i.e. emphysema lose elasticity and diameter) or low lung (i.e. restrictive lung disease) volume

Question 18

smoking effects on lungs

Answer 18

decreasing the pulmonary capillary cross-sectional area (destroy alveolar membrane)

increased pulmonary artery pressure.

Question 19

vasoconstriction and vasodilation hormones affecting pulmonary vascular resistnace

Answer 19

Vasoconstrictors: Serotonin, norepinephrine, histamine, thromboxane A2, and leukotrienes (esp at low lung volumes)

Vasodilators: adenosine, acetylcholine, prostacyclin (prostaglandin I2), and isoproterenol.

Question 20

drugs that relieve pulmonary hypertension via vasodilation

Answer 20

Nitric oxide and phosphodiesterase type V inhibitors such as sildenafil

Question 21

Hypoxia Increases Pulmonary Vascular Resistance

Answer 21

small arteries constrict (stimulate smooth muscle cells) in response to low alveolar oxygen (hypoxia and hypoxemia)

increases resistnace

helps optimize gas exhange by diverting blood away from poorly ventilated alveoli to well ventilated one

Reminder: Hypoxemia causes vasodilation in systemic vessels

Question 22

what accentuates Hypoxia Increases Pulmonary Vascular Resistance

Answer 22

high CO2 and low blood pH

Question 23

regional hypoxia in lungs vs generalized hypoxia

Answer 23

localize vasoconstriction to specific lung regions and divert blood away (little effect on pulmonary arterial pressure or resistance)

general increases resistnace and pulmonary artery pressure (i.e. asthma, emphysema, cystic fibrosis, high altitude)

Question 24

generalized hypoxia examples

Answer 24

pulmonary hypertension

right ventricular hypertrophy

(increase pressure and resistance)

Question 25

Hypoxic Pulmonary Vasoconstriction fetal vs after birth

Answer 25

fetal: dont need lungs for gas exhange so blood shunted away from lungs 1st breath: pulmonary arterioles dilate and resistnace decrasees then after birth HPV will shunt blood away from poorly ventilated regions --> improve ventilation to perfusion matching

Question 26

gravity and blood flow to lungs

Answer 26

underperfused at apex (top) overperfused at base (bottom)

Question 27

3 lung zones depend on relationship between which 3 factors

Answer 27

pulmonary arterial pressure (Pa), pulmonary venous pressure (PV), and alveolar pressure (PA)

Question 28

3 lung zones pulmonary arterial pressure (Pa), pulmonary venous pressure (PV), and alveolar pressure (PA)

Answer 28

zone 1 (least perfused @ apex) PA > Pa > Pv --> if alveolar pressure greater than arterial pressure then no blood flow (bc want to go high to low pressure) --> alveolar dead space (ventilated but not perfused) zone 2 Pa > PA > Pv zone 3 (most perfused) Pa > Pv > PA capillaries become more distended and resistance decreases as go down

Question 29

which muscles require nervous stimulation to contract for breathing

Answer 29

diaphragm and intercostals

Question 30

where is the respitarpy control center/ central pattern generator

Answer 30

pons and medulla

Question 31

inputs to the respiratory control center (pons and medulla)

Answer 31

1. mechanoreceptors (stretch, j receptors, irritants) 2. central chemoreceptors 3. peripheral chemoreceptors (carotid and aortic) 4. muscle proprioceptors

Question 32

which emotions and which brain areas are descending inputs on lung function at respiratory control center (pons and medulla)

Answer 32

rage and fear in hypothalamic and limbic system for voluntary control (cerebrum)

Question 33

medulla has 2 groups for which breathing

Answer 33

DRG (dorsal respiratory group) for inspiration --> diaphragm and intercostal muscles --> nucleus of tractus solitarius VRG (ventral respiratory group) for active respiration --> pre-botzinger complex (rhythogenesis) cross communication between VRG and DRG for synchrony and rhythmic movement s

Question 34

DRG vs VRG

Answer 34

DRG (inspiration) -nucleus of tracts solitarius VRG (active expiration and inspiration) - pre-botzinger complex (rhythogenesis)

Question 35

2 pontine respiratory groups

Answer 35

1. apneustic centers: (stimulate DRG) for controlling deep inspiration 2. pneumotaxic centers: (inhibit DRG) for relaxation after inspiration

Question 36

central inspiratory activity (CIA) gets switched off by

Answer 36

expiration - neurons in VRG and rostral pons

Question 37

stretch receptors initiate which reflex

Answer 37

hering-breuer reflex (lung inflation reflex) to increase breathing frequency and prevent hyperinflation

Question 38

juxtapulmonary capillary J receptors function

Answer 38

increase ventilation in lung edema (give feedback about fluid volume adjacent to alveoli and pulmonary capillaries)

Question 39

how muscles impact rate of breathing

Answer 39

limb velocity, movement, weight load on limb

Question 40

arterial PCO2 increases or if the arterial PO2 decreases or if pH decreases. then ventilation

Answer 40

increases

Question 41

central and peripheral chemoreceptors affecting respiration (PaO2, PaCO2, pH)

Answer 41

central: CO2/ph changes in the lower brainstem peripheral: carotid arteries and aortic arch

Question 42

what is not sensed in the brain (because of blood brain barrier preventing H+ from crossing) and rely on input from peripheral chemoreceptors

Answer 42

arterial PO2 and arterial pH The BBB is impermeable to charged ions like H⁺, preventing direct entry into the brain. However, CO₂ is highly lipid-soluble and CAN cross the BBB freely.

Question 43

Hypoxic-induced Ventilatory Response what is it mediated by

Answer 43

increase in ventilation triggered by low arterial oxygen levels (PaO₂) via peripheral chemoreceptors

Question 44

what are the only receptors that response to PaO2

Answer 44

peripheral chemoreceptors *hypoxemia

Question 45

4 causes of reduced PO2 in arterial blood

Answer 45

1. hypoventilation 2. diffusion impairment 3. shunt 4. ventilation-perfusion inequality

Question 46

central and peripheral causes of hypoventilation

Answer 46

central- outside of lung (drugs, medulla encephalitis, cervical spine injury, hangman fracture C2 spine, C4 spine quadriplegia) peripheral- lung disease (COPD, Duchenne, Gillian barre, myasthenia gravis, obesity hurts thoracic cage)

Question 47

hypoventilation will cause a rise in diagnostic feature sx what is not a feature

Answer 47

diagnostic: PCO2 respiratory acidosis - pH 7.2, altered mental state Hypoxemia is not the dominant feature of hypoventilation.

Question 48

diffusion impairment causing hypoxemia

Answer 48

thickened blood gas barrier slows diffusion i.e. interstitial fibrosis (widen walls), hypoxemia worse during exericse

Question 49

shunt definition

Answer 49

unventilated but perfused area of the lung

Question 50

shunts causing hypoxemia

Answer 50

anatomic shunt: bypass alveoli through a channel i.e. from right to left heart

Question 51

what wont help a shunt

Answer 51

if just give oxygen it wont help increase arterial PO2

Question 52

intrapulmonary shunts

Answer 52

alveoli are perfused but not ventilated i.e. respiratory distress syndrome, pneumonia, pulmonary edeme

Question 53

extra pulmonary shunts

Answer 53

congenital heart disease (atrial or ventricular septal defects) i.e. right to left shunt

Question 54

shunts and dead space relationship

Answer 54

Both shunts and dead space cause ventilation-perfusion (V/Q) mismatches but in opposite ways. shunt: Blood reaches the alveoli without gas exchange due to absent or impaired ventilation. shunt: unventilated but perfused area of lung deadspace: Air reaches alveoli, but no blood flow is available for gas exchange. Dead space refers to areas of the respiratory system where ventilation occurs, but no gas exchange takes place

Question 55

ventilation-perfusion inequalities causing hypoxemia what ratio causes

Answer 55

~1 COPD, parenchymal lung disease, pulmonary embolism, pulmonary hypertension

Question 56

COPD have elevated ____ but they _____ what should you not do

Answer 56

CO2 (hypercapnia) but they adapt to tolerate high arterial PCO2 and rely on hypoxemia to drive ventilation supplemental O2 may cause these patients to stop breathing because arterial PO2 is increased abruptly, removing their drive to breathe

Question 57

exercise induced hyperpnea (increase depth and breath rate) is not Fromm

Answer 57

Arterial PCO2, pH, or PaO2 are not involved

Question 58

3 mechanisms of breathing during exercise

Answer 58

phase 1 neurological phase (medullary generator) phase 2 metabolic phase (increase alveolar ventilation, no change in PaCO2) phase 3 compensatory phase (shift from aerobic to anaerobic; lactic acid by product instead of CO2)

Question 59

sleep via breathing small rise in vulnerable if

Answer 59

withdrawal from wakefulness stimuli via brainstem reticular formation depressed breathing small rise in PaCO2 vulnerable if have respiratory muscle weakness, impaired gas exhange etc. (nocturnal before diurnal problems)

Question 60

intermittent hypoxemia in sleep 2 types

Answer 60

apnea and hypopneas apnea: >90% for >10secs hypopnea >50% for >10 secs

Question 61

obstructive sleep apnea

Answer 61

Respiratory center remains active Paradoxical movement of chest and abdomen upper airway collapse (tongue move back, pharyngeal walls collapse, enlarge tonsils)

Question 62

central sleep apnea (i.e. from CNS injury or if healthy in high altitude)

Answer 62

Respiratory center is inactive The absence of paradoxical movement of chest and abdomen

Question 63

obstructive vs central sleep apnea

Answer 63

both have cessation of airflow, oxygen desaturation and arousal from sleep in OSA:respiratory center active and theres paradoxical chest and ab mvoemtns in CSA: respiratory center inactive and absence of paradoxical movements

Question 64

central sleep apnea in heart failure: cheyne strokes respiration

Answer 64

periodic breathing: apnea and hyperpnea respiration waxes and wanes in crescendo-decresendo pattern

Question 65

cheynes stokes respiration pathogenesis

Answer 65

lung congestion stimulates the j receptors hyperventilate reduce PaCO2 central apnea

Question 66

congenital central hypoventilation

Answer 66

box shapes face, decreased forehead lobe, PHOX2B gene

Question 67

central sleep apnea

Answer 67

idiopathic neurologic disease (i.e. myasthenia gravis, encephalisitis)

Question 68

obesity hypoventilation syndrome (pickwickian syndrome)

Answer 68

obese, hyperventilate and daytime hypercapnia

Question 69

Nocturnal Oximetry
 Obesity Hypoventilation Syndrome

Answer 69

severe OSA resolved with CPAP machine from prolonged obesity hypoventilation syndrome

Question 70

pulmonary edema

Answer 70

accumulate fluid in interstial and alveolar spaces (from heart or lung disease)

Question 71

2 stages of pulmonary edema

Answer 71

2. interstitial (widen alveolar wall interstitium, fluid leaked to perivascular and peribronchial spaces) 2. alveolar (fluid crosses epithelium causing alveolar edema)

Question 72

transition from interstitial to alveolar edema

Answer 72

lymphs are overloaded pressure in interstitial spaces increases and fluid spills into alveoli alveolar epithelium also damaged and increased permeability protein and red cells in alveolar fluid

Question 73

interstitial vs alveolar edema

Answer 73

interstitial doesnt effect pulmonary function much alveolar prevents ventilation --> hypoxemia

Question 74

Edema in the Perivascular or Peribronchial Region Reduces ___

Answer 74

the Caliber of Vessels & Airways compresses vasculature (reduce caliber and lead to pulmonary vascular resistnace) and compress airways (narrow bronchioles and airways)

Question 75

alveolar edema sx

Answer 75

dyspnea, orthopnea, cough up pink fluid hypoxemia

Question 76

causes of pulmonary edema

Answer 76

increased capillary hydrostatic pressure (i.e. heart failure, myocardial infarction) increased capillary permeability (i.e toxin, sepsis) reduced lymph drainage decreased interstitial pressure decrease colloid osmotic pressure

Question 77

check for pulmonary edema via

Answer 77

radiograph

Question 78

pulmonary embolism

Answer 78

thrombi in large veins travel to lungs and occlude pulmonary circulation

Question 79

2 types of pulmonary emblism

Answer 79

1. venous thrombi 2. nonthrombotic emboli: fat, air, amniotic fluid

Question 80

venous trombi ____ triad

Answer 80

from deep veins in lower (or upper) virchows triad: stasis of blood, hyper coagulability, abnormal vessel wall

Question 81

dif sized emboli

Answer 81

small= asymptomatic massive= shock, pallor, cardiac arrest, hypotension

Question 82

cor pulmonale

Answer 82

right ventricular failure from high pulmonary artery pressures (i.e. pulmonary emboli, pulmonary vascular disease, or parenchymal disease like COPD)