Respiratory Physiology

Front 1

Three functions of the respiratory system?

Back 1

1.ventilation-moves air in and out of lungs for gas exchange with blood (external respiration)
2.gas exchange-between blood and tissues via diffusion
3.O2 utilization (cellular respiration)-O2 use by tissues is internal respiration

Front 2

What are the structures involved in in the respiratory system in order of air movement?

Back 2

Air passes from mouth to trachea to right and left bronchi to bronchioles to terminal bronchioles to respiratory bronchioles to alveoli

Front 3

What are the two thin cells located between the lung air and the blood?

Back 3

1 alveolar and 1 endothelial cell

Front 4

What is the function of the conducting zone?

Back 4

1.Warms and humidifies inspired air
2.Mucus lining filters and cleans inspired air
3.Mucus is removed by cilia to be expectorated or swallowed.

Front 5

What is the thoractic cavity and what does it contain?

Back 5

1.A dome-shaped sheet of skeletal muscle created by the diaphragm
2.Contains heart, large blood vessels, trachea, esophagus, thymus, and lungs

Front 6

What is the abdominal cavity and what does it contain?

Back 6

1. Cavity located below the diaphragm
2.Contains liver, pancreas, GI tract, spleen, and genitourinary tract

Front 7

What is the Intrapleural space?

Back 7

1. thin fluid layer between visceral pleura covering lungs and parietal pleura lining thoracic cavity walls

Front 8

What are the physical aspects of ventilation?

Back 8

1.Ventilation results from pressure differences induced by changes in lung volumes
2,Air moves from higher to lower pressure
3.Compliance, elasticity, and surface tension of lungs influence ease of ventilation

Front 9

What are the intrapulmonary pressure during inspiration and expiration?

Back 9

-3mm Hg pressure,+3 mm Hg pressure

Front 10

What is responsible for keeping the lungs inflated?

Back 10

Positive transmural pressure (intrapulmonary - intrapleural pressure)

Front 11

What is Boyle's Law and

Back 11

1.Implies that changes in intrapulmonary pressure occur as a result of changes in lung volume
2.Pressure of gas is inversely proportional to volume
3.P = 1/V

Front 12

What causes inspiration and expiration?

Back 12

1.Increase in lung volume decreases intrapulmonary pressure
2.Decrease in lung volume raises intrapulmonary pressure causing

Front 13

What is compliance?

Back 13

1.how easily lung expands with pressure
2. or change in lung volume per change in transmural pressure (DV/DP)
3. reduced by factors that cause resistance to distension (e.g. pulmonary fibrosis)

Front 14

What is elasticity?

Back 14

1. Is tendency to return to initial size after distension
2. Due to high content of elastin proteins
3. Elastic tension increases during inspiration and is reduced by recoil during expiration

Front 15

How does surface tension affect respiration?

Back 15

1.it and elasticity are forces that promote alveolar collapse and resist distension
2. Force is directed inward, raising pressure in alveoli
3. A film ,secreted by the lungs and absorb fluid, forms that created this because of H2O molecules attracted to each other?

Front 16

What is the Law of Laplace and how is it solved?

Back 16

1.pressure in alveolus is directly proportional to ST; and inversely to radius of alveoli
2.Thus, pressure in smaller alveoli would be greater than in larger alveoli, if ST were same in both
3.Solved by secretion of surfactant

Front 17

What is surfactant?

Back 17

1.Consists of phospholipids secreted by Type II alveolar cells
2.Lowers ST by getting between H2O molecules, reducing their ability to attract each other via hydrogen bonding
3.Prevents ST from collapsing alveoli
4.secretion begins in late fetal life

Front 18

What is Respiratory Distress Syndrome or RDS)?

Back 18

Premies are often born with immature surfactant system

Front 19

What is acute respiratory distress syndrome (ARDS)?

Back 19

1. In adults only
2. caused by septic shock
3.decreases compliance and surfactant secretion

Front 20

What are the mechanics of breathing?

Back 20

1.Pulmonary ventilation consists of inspiration (= inhalation) and expiration (= exhalation)
2.Accomplished by alternately increasing and decreasing volumes of thorax and lungs

Front 21

What is quiet breathing?

Back 21

1.Inspiration occurs mainly because diaphragm contracts, increasing thoracic volume vertically
2.Parasternal and external intercostal contraction contributes a little by raising ribs, increasing thoracic volume laterally
3.Expiration is due to passive recoil

Front 22

What is deep breathing?

Back 22

1.Forced inspiration involves contraction of extra muscles to elevate ribs: scalenes, pectoralis minor, and sternocleidomastoid muscles
2.Forced expiration involves contraction of internal intercostals and abdominal muscles

Front 23

What is Pulmonary Function Tests

Back 23

Assessed clinically by spirometry, a method that measures volumes of air moved during inspiration and expiration

Front 24

What is Anatomical dead space

Back 24

air in conducting zone where no gas exchange occurs (about 150 ml)

Front 25

What is tidal volume?

Back 25

amount of air expired/breath in quiet breathing

Front 26

What is Vital capacity?

Back 26

amount of air that can be forcefully exhaled after a maximum inhalation
= sum of inspiratory reserve, tidal volume, and expiratory reserve

Front 27

What is Total minute volume?

Back 27

tidal volume X breath per minute

Front 28

What is partial pressure?

Back 28

pressure that a particular gas in a mixture exerts independently

Front 29

What is Dalton's Law?

Back 29

states that total pressure of a gas mixture is the sum of partial pressures of each gas in mixture

Front 30

What causes gas exchange in the lungs?

Back 30

1. Is driven by differences in partial pressures of gases between alveoli and capillaries
2. Is facilitated by enormous surface area of alveoli, short diffusion distance between alveolar air and capillaries, and tremendous density of capillaries

Front 31

When does O2 in blood reach its maximum value?

Back 31

When blood and alveolar air are at equilibrium

Front 32

What is Henry’s Law?

Back 32

1.says that this value depends on solubility of O2 in blood (a constant), temperature of blood (a constant), and partial pressure of O2
2. So the amount of O2 dissolved in blood depends directly on its partial pressure (PO2), which varies with altitude

Front 33

Why do we need pO2 and PCO2 measurements and what is normal for blood and veins?

Back 33

1.Provide good index of lung function
2.At normal PO2 arterial blood has about 100 mmHg PO2
3.PO2 is about 40 mmHg in systemic veins
4. PCO2 is 46 mmHg in systemic vein

Front 34

Describe pulmonary circulation?

Back 34

1.Rate of blood flow through pulmonary circuit equals flow through systemic circulation
2. lower pressure (15 mm Hg)
3. Pulmonary vascular resistance is low
4.Low pressure produces less net filtration than in systemic capillaries
Avoids pulmonary edema
5.Pulmonary arterioles constrict where alveolar PO2 is low and dilate where high

Front 35

Describe the Lung Ventilation/Perfusion Ratios?

Back 35

1.Normally, alveoli at apex of lungs are underperfused and overventilated
2.Alveoli at base are overperfused and underventilated

Front 36

Describe the brains effect on the respiration system?

Back 36

1. Automatic breathing is generated by a rhythmicity center in medulla oblongata
2.Consists of inspiratory neurons that drive inspiration and expiratory neurons that inhibit inspiratory neurons
3.Their activity varies in a reciprocal way and may be due to pacemaker neurons
4.Activities of medullary rhythmicity center are influenced by centers in pons

Front 37

How do chemoreceptors effect breathing?

Back 37

1. They influence automatic breathing?
2. Also monitor blood PO2, PO2. and pH
3.modify ventilation to maintain normal CO2, O2, and pH levels

Front 38

Where are central and peripheral chemoreceptors located?

Back 38

1. the medulla
2. large arteries near heart (aortic bodies) and in carotids (carotid bodies)

Front 39

What is hypocapnia?

Back 39

low CO2 caused by hyperventilation

Front 40

What is hypercapnia?

Back 40

high CO2 caused by hypoventilation

Front 41

What is the pressure of CO2 so important?

Back 41

It is the most crucial component in effecting the blood pH

Front 42

What are the Effects of Blood PCO2 and pH on Ventilation?

Back 42

1. Brain chemoreceptors are responsible for greatest effects on ventilation
2. H+ can't cross BBB but CO2 can, which is why it is monitored and has greatest effects
3.Rate and depth of ventilation adjusted to maintain arterial PCO2 of ~40 mm Hg
4. Peripheral chemoreceptors do not respond to PCO2, only to H+ levels

Front 43

What are the effects of PO2 on ventilation?

Back 43

1. Low blood PO2 (hypoxemia) has little effect on ventilation
2. Does influence chemoreceptor sensitivity to PCO2
3. PO2 has to fall to about half normal before ventilation is significantly affected

Front 44

What is hemoglobin and how does it effect O2 transport?

Back 44

1. Each Hb has 4 globin polypeptide chains and 4 heme groups that bind O2
2.Each heme has a ferrous ion that can bind 1 O2
So each Hb can carry 4 O2s
3. Loading of Hb with O2 occurs in lungs; unloading in tissues
4. Affinity of Hb for O2 changes with a number of physiological variables
5. Each RBC has about 280 million molecules of Hb
6. Hb greatly increases O2 carrying capacity of blood

Front 45

What is oxyhemoglobin?

Back 45

hemoglobin bound to oxygen found within the RBC's

Front 46

What is Methemoglobin?

Back 46

1. contains ferric iron (Fe3+) -- the oxidized form
2. Lacks electron to bind with O2
3. Blood normally contains a small amount

Front 47

What is Carboxyhemoglobin?

Back 47

1. heme combined with carbon monoxide
2. Bond with carbon monoxide is 210 times stronger than bond with oxygen
3. So heme can't bind O2

Front 48

What is anemia?

Back 48

1. Hb levels are below normal
2. causing each RBC to produce more DPG

Front 49

What is polycythemia?

Back 49

Hb levels are above normal

Front 50

What is erythropoietin (EPO) and what does it controls?

Back 50

1. it is the controlling factor of hemoglobin
2. Production stimulated by low PO2 in kidneys

Front 51

Why are Hb levels higher in males?

Back 51

because androgens promote RBC production

Front 52

What is Hb affinity?

Back 52

1.Ideally, Hb-O2 affinity should allow maximum loading in lungs and unloading in tissues
2. High PO2 of lungs favors loading; low PO2 in tissues favors unloading

Front 53

Describe the Oxyhemoglobin Dissociation Curve?

Back 53

1. Gives % of Hb sites that have bound O2 at different PO2s
2. Reflects loading and unloading of O2
3. Differences in % saturation in lungs and tissues are shown at right
4. In steep part of curve, small changes in PO2 cause big changes in % saturation
5. Is affected by changes in Hb-O2 affinity caused by pH and temperature

Front 54

What is Bohr effect?

Back 54

1. Affinity decreases when pH decreases or temperature increases.
2. Occurs in tissues where temp, CO2 and acidity are high
3. Causes Hb-O2 curve to shift right and more unloading of O2

Front 55

What is the Effect of 2,3 DPG on O2 Transport?

Back 55

1. Since RBCs have no mitochondria they can't perform aerobic respiration.
2. 2,3-DPG is a byproduct of glycolysis in RBCs
3. Its production is increased by low O2 levels
4. Causes Hb to have lower O2 affinity, shifting curve to right

Front 56

What is Fetal hemoglobin (HbF)?

Back 56

1. 2 g-chains in place of b-chains of HbA
2. HbF can’t bind DPG, causing it to have higher O2 affinity
3. Facilitates O2 transfer from mom to baby

Front 57

What is Sickle-cell anemia?

Back 57

1. affects 8-11% of African Americans
2. HbS has valine substituted for glutamic acid at 1 site on b chains
3. At low PO2, HbS crosslinks to form a “paracrystalline gel” inside RBCs
4. Makes RBCs less flexible and more fragile

Front 58

What is Myoglobin?

Back 58

1. Is a red pigment found exclusively in striated muscle
2. Slow-twitch skeletal and cardiac muscle fibers are rich in this
3. Has only 1 globin; binds only 1 O2
4. Has higher affinity for O2 than Hb; is shifted to extreme left
5. Releases O2 only at low PO2
6. Serves in O2 storage, particularly in heart during systole

Front 59

What is carbonic anhydrase?

Back 59

1. catalyzes formation of H2CO3 from CO2 + H2O in RBCs
2 CO2 transported in blood as dissolved CO2 (10%), carbaminohemoglobin (20%), and bicarbonate ion, HCO3-, (70%)

Front 60

What is the chloride shift?

Back 60

1. Cl- moves into RBC
2. caused by HCO3- diffuses down concentration and charge gradient into blood causing RBC to become more +
3. High CO2 levels is main cause

Front 61

What is the Reverse Chloride Shift?

Back 61

1. In lungs, CO2 + H2O  H2CO3  H+ + HCO3-, moves to left as CO2 is breathed out
2. Binding of O2 to Hb decreases its affinity for H+
3. H+ combines with HCO3- and more CO2 is formed
4. Cl- diffuses down concentration and charge gradient out of RBC

Front 62

Describe acid-base balance in the blood?

Back 62

1. Blood pH is maintained within narrow pH range by lungs and kidneys (normal = 7.4)
2. Most important buffer in blood is bicarbonate
3. Excess H+ is buffered by HCO3-
Kidney's role is to excrete H+ into urine

Front 63

What is difference between volatile and involatile acids in the body?

Back 63

1. can be converted to gas
2. cannot leave the blood

Front 64

Compare acidosis and alkalosis?

Back 64

1. when pH < 7.35;
2. is pH > 7.45

Front 65

Compare Respiratory acidosis and Respiratory alkalosis.

Back 65

1. caused by hypoventilation
Causes rise in blood CO2 and thus carbonic acid
2. caused by hyperventilation
Results in too little CO2

Front 66

Compare Metabolic acidosis and
Metabolic alkalosis.

Back 66

1.results from excess of nonvolatile acids
E.g. excess ketone bodies in diabetes or loss of HCO3- (for buffering) in diarrhea
2. caused by too much HCO3- or too little nonvolatile acids (e.g. from vomiting out stomach acid)

Front 67

What is Respiratory Acid-Base Balance?

Back 67

1 Ventilation usually adjusted to metabolic rate to maintain normal CO2 levels

Front 68

Compare respiratory acidosis and respiratory alkalosis?

Back 68

1. With hypoventilation not enough CO2 is breathed out in lungs
Acidity builds
2. With hyperventilation too much CO2 is breathed out in lungs
Acidity drops

Front 69

What are the effect on ventalation during exercise?

Back 69

1. arterial PO2, PCO2, and pH remain fairly constant
2. breathing becomes deeper and more rapid, delivering much more air to lungs (hyperpnea)

Front 70

Compare With neurogenic mechanism
and humoral mechanism?

Back 70

1. sensory activity from exercising muscles stimulates ventilation; and/or motor activity from cerebral cortex stimulates CNS respiratory centers
2. either PCO2 and pH may be different at chemoreceptors than in arteries

Front 71

Describe the Lactate Threshold?

Back 71

1. Is maximum rate of oxygen consumption before blood lactic acid levels rise as a result of anaerobic respiration
2. Occurs when 50-70% maximum O2 uptake has been reached
3. Endurance-trained athletes have higher this , because of higher cardiac output
4. Have higher rate of oxygen delivery to muscles and greater numbers of mitochondria and aerobic enzymes

Front 72

How does high altitude effect the respiratory system?

Back 72

increased ventilation, increased DPG, and increased Hb levels

Front 73

What is Hypoxic ventilatory response?

Back 73

1. initiates hyperventilation which decreases PCO2 which slows ventilation
2. Chronic hypoxia increases NO production in lungs which dilates capillaries there
3. NO binds to Hb and is unloaded in tissues where may also increase dilation and blood flow
4. NO may also stimulate CNS respiratory centers
5. Altitude increases DPG, causing Hb-O2 curve to shift to right
6. Hypoxia causes kidneys to secrete EPO which increases RBCs