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Human Physiology > Respiratory System > Flashcards

Respiratory System Flashcards

1
Q

What are the 4 key functions of the respiratory system

A

Exchange of gases between the atmosphere and blood, homeostatic regulation of body pH, protection from inhaled pathogens and irritating substances, and vocalization

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2
Q

What is external respiration

A

Movement of gases between atmosphere and body’s cells

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3
Q

What are the 4 parts of external respiration

A

Ventilation, gas exchange between lungs and blood, gas transport, and gas exchange between blood and body tissues

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4
Q

What is ventilation

A

Exchange of air between atmosphere and lungs (inspiration and expiration) in airways

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5
Q

What does gas exchange between the lungs and blood happen

A

O2 and CO2 exchanged between alveoli and pulmonary capillaries

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6
Q

Where does gas exchange between blood and body cells occur

A

O2 and CO2 exchanged between capillaries and cells

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7
Q

What is cellular respiration

A

Intracellular processes (Krebs cycle, etc.) using O2 to generate ATP, CO2, and H2O

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8
Q

What do the conducting airways do

A

Warm air to body temperature, add water vapor until the air reaches 100% humidity, and filter out foreign material

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9
Q

Why do the conducting airways branch

A

To increase surface area and thus diffusion (Fick’s Law)

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10
Q

What are alveoli

A

Air sacs and capillaries made of 1 epithelial layer for pulmonary circulation

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11
Q

What are the 2 cell types of the alveoli epithelial layer and what do they do

A

Type I (95%) is involved in gas exchange, and type II secretes alveolar fluid and surfactant

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12
Q

What is surfactant

A

Mixes with alveolar fluid (saline-like) to decrease surface tension (helps lungs inflate and expand), be a protective layer, solvent, and environment for macrophages

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13
Q

What is airflow proportional to

A

Pressure gradient/R

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14
Q

What drives airflow (ventilation)

A

Muscular contractions create pressure gradient (quiet breathing and forced expiration)

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15
Q

What are the 2 phases of the respiratory cycle

A

Inspiration (inhalation) and expiration (exhalation)

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16
Q

What is Boyle’s law

A

P1V1 = P2V2 –> Pressure is inversely related to the size of the container

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17
Q

How do the diaphragm and thoracic cage change during inspiration

A

Diaphragm contracts and flattens, while ribs move up and away from the spine like a water lever

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18
Q

How do the diaphragm and thoracic cage change during expiration

A

Diaphragm relaxes, thoracic volume decreases as ribs move outward laterally (like water bucket handle)

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19
Q

What contributes to 60-75% of inspiratory volume change

A

Diaphragm movement

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20
Q

What contributes to remaining 25-40% of inspiratory volume change?

A

Movement of the rib cage (external intercostals and scalenes)

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21
Q

What are pleural sacs

A

Balloon like structures surrounding each lung

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22
Q

What is the space between the lungs and the pleural membrane called

A

Intrapleural space filled with pleural fluid

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23
Q

What are the 2 functions of pleural fluid

A

To create a moist, slippery surface that allows pleural membranes to slide across each other (pleurisy when lack of pleural fluid), as well as keep lungs adhered to the chest wall

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24
Q

What happens if the pleural cavity is opened to the atmosphere

A

Air flows in (because of smaller subatomic pleural cavity pressure), the bond holding the lung to the chest wall is broken, and the lung collapses (pneumothorax)

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25
Q

What is most of the work in breathing

A

Overcoming resistance of elastic lungs to stretching (like a rubber band)

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26
Q

What is compliance

A

Ability of the lungs to stretch (high = easy, low = needs more force)

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27
Q

What are restrictive lung diseases

A

The lungs have low compliance and require more work to expand, eg. with fibrotic lung diseases (scar tissue/collagen) or inadequate surfactant production (like in newborn respiratory distress system)

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28
Q

What is elastance

A

The ability of the lungs to return to normal after stretch (elastic recoil)

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29
Q

What decreases elastance

A

Smoking (macrophages degrade elastic fibers) and emphysema (high compliance but poor elastance)

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30
Q

What paracrine influence the smooth muscle of bronchioles

A

Primarily CO2, but also histamines and the ANS

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31
Q

How does CO2 affect bronchioles

A

Increased concentrations in expired air relaxes smooth muscles and causes dilation (less resistance and more flow)

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32
Q

How does histamine affect bronchioles

A

Released by mast cells (due to damage or allergic reaction) it causes constriction to prevent pathogens from coming in (increase resistance, decrease flow)

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33
Q

How does the ANS affect bronchioles

A

PSNS bronchioconstricts while SNS (epinephrine and B-2) has no direct innervation

34
Q

What device measures volume of air moved with each breath

A

Spirometers

35
Q

What is the difference between end of normal inspiration and end of normal expiration

A

Tidal volume (~500 mL)

36
Q

What is minute (total pulmonary) ventilation (VeATP)

A

Volume of air moved in or out of the lungs each minute (~6L/min)

37
Q

What is the equation for minute ventilation

A

VeATP = breathing rate (breaths/min) * tidal volume (ml/breath)

38
Q

What is hypoxia

A

Insufficient O2 availability to cells

39
Q

What is hypercapnia

A

Elevated CO2 levels that change blood pH

40
Q

What is it called when alveolar ventilation decreases

A

Hypoventilation

41
Q

What is it called when alveolar ventilation increases

A

Hyperventilation

42
Q

What happens during hypoventilation

A

Alveolar P(O2) decreases and (P(CO2) increases

43
Q

What can cause hypoventilation

A

CNS depression (alcohol poisoning, drug overdose)

44
Q

What happens during hyperventilation

A

Alveolar P(O2) increases and P(CO2) decreases

45
Q

What can cause hyperventilation

A

Anxiety, panic stress, stimulants, and/or severe pain

46
Q

What is P(O2) and P(CO2) in the alveoli

A

P(O2) = 100mmHg
P(CO2) = 40mmHg

47
Q

What is P(O2) and P(CO2) in the arterial blood

A

P(O2) = 100mmHg
P(CO2) = 40mmHg

48
Q

What is P(O2) and P(CO2) in the cells

A

P(O2) <= 40mmHg
P(CO2) >= 46mmHg

49
Q

What is P(O2) and P(CO2) in the venous blood

A

P(O2) <= 40 mmHg
P(CO2) >= 46mmHg

50
Q

What is the concentration of gases in the atmosphere

A

79% N2, 21% O2, 0.03% CO2

51
Q

What is Dalton’s law

A

Total pressure exerted by a mixture of gases = sum of pressures exerted by the individual gases

52
Q

What is partial pressure

A

The pressure of a single gas

53
Q

What is the equation for partial pressure

A

P(gas) = P(atm) * % of gas in atmosphere

54
Q

Does the % of gas in the atmosphere ever change

A

No, but P(atm) does

55
Q

What 3 things does alveolar gas exchange (diffusion rate) depend on

A

Partial pressure (concentration) gradient (directly proportional), surface area available for gas exchange (directly proportional), and diffusion distance including membrane thickness (inversely proportional) –> None usually vary

56
Q

What is emphysema

A

Damage from smoking, etc. to alveolar sacs that merges them to decrease surface area)

57
Q

What affects partial pressure gradients of gases (respiratory system)

A

Altitude and hypoventilation

58
Q

What effects diffusion distance

A

Fibrotic lung disease and pulmonary edema

59
Q

What is pulmonary edema

A

Fluid in the lungs (e.g congestive heart failure, pneumonia)

60
Q

What is Henry’s Law

A

Movement of gases from air to liquid is proportional to the pressure gradient, temperature, and solubility (how easily gas dissolves in a liquid)

61
Q

Which is more soluble, O2 or CO2

A

CO2 (20x more soluble)

62
Q

How is O2 carried in blood

A

98% is reversibly bound to hemoglobin in red blood cells, the rest is dissolved

63
Q

What is the law of mass action

A

High O2 (PO2) concentration = high binding vs. low O2 concentration = low binding = O2 released to diffuse into cells

64
Q

How many O2 can 1 hemoglobin bind

A

4

65
Q

What is % Hb saturation

A

% of available binding sites that are being used (normal is 98%)

66
Q

What is the primary determinant of %Hb saturation

A

Plasma PO2

67
Q

What is affinity

A

Degree to which a protein is attracted to it’s ligand, affected by protein shape (allosteric modulation)

68
Q

What effect does pH have on hemoglobin’s affinity for O2

A

Bohr effect/shift: Decrease in pH, increases H+, increases O2 release at tissues (left shift)

69
Q

What effect does temperature have on hemoglobin’s affinity for O2

A

Increase in temp increases O2 release at tissues

70
Q

What effect does PCO2 have on hemoglobin’s affinity for O2

A

Increase in PCO2 increases O2 release at tissues

71
Q

What effect does 2,3-BPG have on hemoglobin’s affinity for O2

A

Released in response to prolonged hypoxia (from altitude or anemia): Increase in BPG increases O2 release at tissues

72
Q

What 3 ways is CO2 transported in the blood

A

Dissolved in plasma (7%), bound to hemoglobin different from O2 binding site(23%), converted to bicarbonate ion (70%)

73
Q

Describe bicarbonate ion (HCO3-)

A

Buffers metabolic acid, reversible bicarbonate buffering reaction driven by carbonic anhydrase enzyme (antiporter transports HCO3-)

74
Q

What is hypercapnia

A

Too much CO2

75
Q

What effect does hypercapnia have on the bicarbonate buffering reaction

A

Right shift, increases H+, decreasing pH, and causing acidosis

76
Q

What effect does alkalosis have on the bicarbonate buffering reaction

A

Right shift, increases CO2, increases H+, decreasing pH

77
Q

How are respiratory skeletal muscles activated

A

By somatic motor neurons controlled by CNS

78
Q

What neurons drive the rhythmic breathing pattern

A

Central pattern generating network (pre-Boetzinger complex) in the medulla oblongata

79
Q

What is the pre-Boetzinger complex

A

Pacemaker neurons controlling inspiratory (DRG) and expiratory (VRG) muscles

80
Q

What 3 sensory signals modify output signals for breathing

A

Chemoreceptors (O2, CO2, and H+), limbic (emotions), and fever

81
Q

What are the 2 types of chemoreceptors that change output signal for breathing and what do they do

A

Central chemoreceptors (medulla) sense change in CO2 and H+ in cerebrospinal fluid, and peripheral chemoreceptors (carotid and aortic arteries) that sense changes in PO2, pH, and PCO2 in blood

82
Q

What is the primary stimulus for changes in ventilation

A

Changes in CO2 affect tidal volume and breathing rate (sensed by peripheral and central chemoreceptors)

Human Physiology (12 decks)

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