Ch. 16 Respiratory System (Day 1) Flashcards

Question

Pneumothorax

Answer 1

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)

Answer 2

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

Answer 3

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

Answer 4

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

Answer 5

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

Answer 6

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

Answer 7

Strong attractive force of hydrogen bonds between water molecules

Answer 8

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

Answer 9

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

Answer 10

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

Answer 11

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

Answer 12

Mechanisms of breathing Inspiration and Expiration Accomplished by changing thoracic cavity/lung volume

Answer 13

Breathe in

Answer 14

Breathe out

Answer 15

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

Answer 16

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

Answer 17

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

Answer 18

1. Thoracic cage expands outward | 2. Diaphragm drops down - contracts and flattens

Answer 19

Side: as ribs move up, sternum is pushed up and out, expanding the cage Front: ribs move up, expanding lateral dimension of rib cage

Answer 20

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

Answer 21

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)

Answer 22

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 - 2. Voluntary ("forced," e.g. exercise) - input from cerebral cortex Pons: 2 respiratory control centers - 1. Apneustic (stimulates inspiratory neurons in medulla) - 2. Pneumotaxic (antagonizes apneustic to inhibit inspiration)