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Physiology (MPP 3202) > Ch. 16 Respiratory System (Day 1) > Flashcards

Ch. 16 Respiratory System (Day 1) Flashcards

1
Q

Ventilation

A

(Breathing)

Mechanical process that moves air into and out of the lungs

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2
Q

Gas Exchange occurs between?

A

Blood and lungs; blood and tissues

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3
Q

Cellular Respiration

A

Oxygen utilization by tissues to make ATP

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4
Q

External Respiration

A

Ventilation and gas exchange in lungs

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5
Q

Internal Respiration

A

Oxygen utilization and gas exchange in tissues

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6
Q

Gas Exchange in Lungs

A
  • Occurs via diffusion
  • O2 concentration in higher in lungs than in blood, so O2 diffuses into blood
  • CO2 concentration in the blood is higher than in lungs, so CO2 diffuses out of blood
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7
Q

Respiratory System Functions (4)

A
  1. Exchange of gases between the atmosphere and the blood - brings in O2, eliminates CO2
  2. Homeostatic regulation of body pH - via selective retention vs excretion of CO2
  3. Protection from inhaled pathogens and irritating substances - via trapping and either expulsion or phagocytic destruction of potentially harmful substances, pathogens
  4. Vocalization - vibrations created by air passing over vocal cords
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8
Q

Overall Structure/Anatomy

A

Trachea –> primary bronchus –> bronchial tree –> terminal bronchioles –> respiratory bronchioles –> alveolar sacs –> alveolus

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9
Q

Conduction Zone function? Includes?

A

Gets air to the respiratory zone

Trachea –> primary bronchus –> bronchial tree –> terminal bronchioles

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10
Q

Respiratory Zone is the site of? Includes?

A

Site of gas exchange

Terminal bronchioles –> respiratory bronchioles –> alveolar sacs –> alveolus

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11
Q

Airways

A

Connect lungs to external environment and warm, humidify, and filter inspired air

Mucus traps small particles, and cilia move it away from the lungs

As progress from trachea through progressive bronchial branchings, total surface area increases by greater than 5 orders of magnetite (greater than 10^5)

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12
Q

Follow the path of air through the airway (starting at nasal cavity)

A

Nasal cavity –> pharynx –> larynx (through the glottis and vocal cords) –> trachea –> R and L primary bronchi –> secondary bronchi –> tertiary bronchi (more branching) –> terminal bronchioles –> respiratory zone (respiratory bronchioles) –> terminal alveolar sacs

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13
Q

Structure of Lung Lobule

A

Each cluster of alveoli is surrounded by elastic fibers and a network of capillaries

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14
Q

Respiratory Zone

A

Alveoli

  • -air sacs where gas exchange occurs
  • -300 * 10^6; provide large surface area (760 ft^2) to increase diffusion rate
  • -each alveolus: one cell layer thick
  • -form clusters at the ends of respiratory bronchioles
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15
Q

What are the 2 types of Alveolar Epithelial Cells?

A

Type 1:
–95-97% total surface area where gas exchange occurs

Type 2:
–secrete pulmonary surfactant and reabsorb sodium and water, preventing fluid buildup

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16
Q

Thoracic Cavity

A

Contains the heart, trachea, esophagus, and thymus w/in the central mediastinum

The lungs fill the rest of the cavity

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17
Q

Parietal Pleura

A

Lines thoracic wall

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18
Q

Visceral Pleura

A

Covers the lungs

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19
Q

Intrapleural Space (Pleural Cavity)

A

The parietal and visceral pleura are normally pushed together, w/ a fluid-filled space between called the Intrapleural Space

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20
Q

Diaphragm

A

Dome-shaped skeletal muscle of respiration that separates the thoracic and abdominal cavities

21
Q

Physical Aspects of Ventilation

A

Air moves from higher to lower pressure

Pressure differences between the two ends of the conducting zone occur due to changing lung volumes

Compliance, elasticity, and surface tension are important physical properties of the lungs

22
Q

Types of Pressure

A
  1. Atmospheric pressure: pressure of air outside the body
  2. Intrapulmonary or intra-alveolar pressure: pressure in the lungs
  3. Intrapleural pressure: pressure w/in the intrapleural space (between parietal and visceral pleura); contains thin layer of fluid to serve as lubricant
23
Q

Pressure Differences when Breathing

A
  1. Inspiration (inhalation): intrapulmonary pressure less than atmospheric pressure
    - -pressure LESS than atmospheric = sub-atmospheric or negative pressure (generally about -3mmHg)
  2. Expiration (Exhalation): intrapulmonary pressure GREATER than atmospheric pressure (generally about +3mmHg)
24
Q

Intrapleural Pressure

A

Less than P(intrapulmonary) and P(atmospheric) in both inspiration and expiration

P(intrapulmonary) - P(intrapleural) = P(trans pulmonary)

Keeps lungs against thoracic wall, allowing lungs to expand during inspiration

In the normal lung at rest, pleural fluid keeps the lung adhered to the chest wall

25
Q

Pneumothorax

A

If the sealed pleural cavity is opened to the atmosphere, air flows in. The bond holding the lung to the chest wall is broken, and the lung collapses, creating a pneumothorax (air in the thorax)

26
Q

Boyle’s Law

A

P is proportional to 1/V

  • -P = pressure; V = volume
  • -assumes temperature constant and closed system

Increased lung volume during inspiration, decreases P(intrapulmonary) to less than P(atmospheric) –> air flows in

Decreased lung volume during expiration –> P(intrapulmonary) greater than P(atmospheric) –> air flows out

27
Q

Lung Compliance

A

Physical property of lungs

  1. Lungs expand when stretched
  2. Defined as change in lung volume per change in transpulmonary pressure: (delta)V/(delta)P
  3. Index of the ease w/ which the lungs expand under pressure
    - High compliance:
    - ->easily stretched
    - Low Compliance:
    - ->requires more force, restrictive lung diseases, e.g. pulmonary fibrosis, surfactant deficiency
28
Q

Lung Elasticity

A
  1. Return to initial size after being stretched
  2. Lungs have elastin fibers
  3. Because the lungs are stuck to the thoracic wall, they are always under elastic tension
  4. Tension increases during inspiration and is reduced by elastic recoil during expiration
29
Q

Surface Tension

A

Exerted by fluid in the alveolus

Resists distention, promotes collapse of alveolar space

Exerted by fluid secreted on the alveoli

Fluid is absorbed by active transport of Na+ and secreted by active transport of Cl-
–any imbalance between these can result in viscous fluid that is difficult to clear –> raises the pressure of the alveolar air as it acts to collapse the alveolus

People w/ cystic fibrosis have a genetic defect that causes such an imbalance of fluid absorption and secretion

30
Q

So what is surface tension?

A

It’s the force holding fluid molecules together at an air-fluid interface

31
Q

Surface tension results from?

A

Strong attractive force of hydrogen bonds between water molecules

32
Q

Law of Laplace

A

Pressure is directly proportional to surface tension and inversely proportional to radius of alveolus

Small alveoli would be at greater risk of collapse w/o surfactant

Ex: 2 different sized bubbles in diagram (notes, p.14) have same surface tension. According to Law of Laplace, pressure is greater in the smaller bubble

33
Q

Surfactant

A

Surface active agent

Secreted by type II alveolar cells

Consists of hydrophobic protein and phospholipids

Reduces surface tension between water molecules by reducing the number of hydrogen bonds between water molecules

More concentrated as alveoli get smaller during expiration

Prevents collapse

Allows a residual volume of air to remain in lungs

34
Q

Surfactant reduces? (2 things)

A
  1. Surface tension. In the lungs, smaller alveoli have more surfactant per unit surface area, which equalizes pressure between large and small alveoli
  2. The work of breathing and prevents smaller alveoli from tempting into bigger alveoli
35
Q

Respiratory Distress Syndrome (RDS)

A

Production of surfactant begins late in fetal life, so premature babies have higher risk for alveolar collapse - Respiratory Distress Syndrome (RDS); treated w/ surfactant

Similar problems may occur in adults w/ septic shock - decrease in lung compliance, decrease in surfactant - acute RDS; not treatable w/ surfactant

36
Q

Pulmonary Ventilation

A

Mechanisms of breathing

Inspiration and Expiration

Accomplished by changing thoracic cavity/lung volume

37
Q

Inspiration (inhalation)

A

Breathe in

38
Q

Expiration (exhalation)

A

Breathe out

39
Q

Muscles of Inspiration

A
  1. Sternocleidomastoid and Scalenes
    - -used for forced inspiration
  2. External Intercostals
    - -raises rib cage during inspiration
  3. Parasternal Intercostals
    - -works w/ external intercostals
  4. Diaphragm
    - -contrats in inspiration - lowers –> enlarging thoracic cavity
    - -relaxes in expiration - raises –> thoracic cavity smaller
40
Q

Muscles of Expiration

A

Quiet expiration occurs w/ the relaxation of the inspiratory muscles (passive process)

  1. Internal Intercostals
    - -lowers rub cage during forced expiration
  2. External Abdominal Oblique, Internal Abdominal Oblique, Transversus Abdominis, Rectus Abdominis
    - -abdominal muscles are also used for forced expiration
  3. Diaphragm
    - -relaxes in expiration - raises –> thoracic cavity smaller
41
Q

Diaphragm at Rest: relaxed or contracted?

A

Relaxed

42
Q

Mechanisms of Breathing: Inspiration

A

Volume of thoracic cavity (and lungs) increases vertically when diaphragm contracts (flattens) and laterally when parasternal and external intercostals raise the ribs
–thoracic and lung volume increase –> intrapulmonary pressure decreases –> air in

43
Q

Inspiration occurs when alveolar pressure ____?

A

Decreases

44
Q

Inspiration: Thoracic Volume Increasing

A
  1. Thoracic cage expands outward

2. Diaphragm drops down - contracts and flattens

45
Q

Inspiration: Side and Front Views

A

Side: as ribs move up, sternum is pushed up and out, expanding the cage

Front: ribs move up, expanding lateral dimension of rib cage

46
Q

Expiration

A

Volume of thoracic cavity (and lungs) decreases vertically when diaphragm relaxes (dome) and laterally when external and parasternal intercostals relax for quiet expiration or internal intercostals contract in forced expiration to lower the ribs
–thoracic and lung volume decreases –> intrapulmonary pressure increases –> air out

Diaphragm and chest wall muscles between ribs relax, and thoracic volume increases

47
Q

Regulation of Ventilation

A

Unlike cardiac muscle, skeletal muscles are NOT spontaneously active, so they must be stimulated by nerve signals

Rhythmic pattern of contraction and relaxation of breathing muscles arises from a neural network of spontaneously discharging motor neurons from cerebral cortex (voluntary breathing) and respiratory control centers of Medulla Oblongata and Pons (involuntary breathing)

Motor neurons - innervate diaphragm/other breathing muscles; regulated by descending neurons from the brainstem (Medulla and Pons)

48
Q

Control of Breathing

A

Medulla:

  • -2 rhythmicity centers: excitatory inspiratory neurons vs neurons which inhibit those inspiratory neurons - intrinsic rhythmicity, but influenced by other factors
    1. Involuntary breathing (e.g. at rest) - intrinsic to medulla
    1. Voluntary (“forced,” e.g. exercise) - input from cerebral cortex

Pons: 2 respiratory control centers

    1. Apneustic (stimulates inspiratory neurons in medulla)
    1. Pneumotaxic (antagonizes apneustic to inhibit inspiration)
49
Q

Regulation of Ventilation is controlled by which nervous system?

A

CNS

Physiology (MPP 3202) (32 decks)

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