Resp 4

Question 1

Scientists initially assumed the major determinant of lung compliance and lung recoil were….

Answer 1

elasticity of pulmonary cells and ECM (elastin and collagen)….FALSE

Question 2

A major determinant of lungs elastic recoil is…

Answer 2

surface tension

Question 3

surface tension

Answer 3

measure of force acting to pull a liquid’s molecules together at an air-water interface

Question 4

Laplace’s equation

Answer 4

P=(2T)/r; T=surface tension (~70dynes/cm), r=bubble radius

Question 5

surfactant

Answer 5

a detergent-like molecule secreted by Type II alveolar cells that reduces surface tension to ~25dynes/cm or less; increasing compliance

Question 6

What is surfactant composed of?

Answer 6

90% phospholipids, 10% protein

Question 7

How does surfactant reduce surface tension?

Answer 7

By decreasing density of water molecules at air-water interfaces

Question 8

Smaller alveoli have ____ surfactant because…

Answer 8

more; it equalizes the pressure between large and small alveoli

Question 9

Rapidly expanding alveolus vs slowly expanding alveolus

Answer 9

-rapidly expanding alveolus greatly reduces surface density of surfactant and increase surface tension and elastic recoil, putting a “brake” on expansion

Question 10

Infant Respiratory Distress Syndrome

Answer 10

affects 1% of new borns; developmental insufficiency of surfactant production and immaturity of the lungs

Question 11

Prevention of Infant Respiratory Distress Syndrome

Answer 11

glucocorticoid injection to the mother

Question 12

Treatment of Infant Respiratory Distress Syndrome

Answer 12

• artificial surfactant
• continuous positive airway pressure (CPAP)
• intubation

Question 13

90% of airway resistance occurs in….

Answer 13

trachea and bronchi

Question 14

Major determinant of bronchoconstriction/dilation (diameter)

Answer 14

CO2

Question 15

high levels of CO2 cause..

Answer 15

dilation

Question 16

low levels of CO2 cause..

Answer 16

constriction

Question 17

histamine

Answer 17

released by cells in response to injury and in allergic and inflammatory reactions, causing contraction of smooth muscle and dilation of capillaries

Question 18

Asthmatic airways have…

Answer 18

wall-inflamed and thickened

Question 19

Asthmatic airway during attack

Answer 19

• air trapped in alveoli

- tightened smooth muscled

Question 20

In respiratory system effectiveness of ventilation is determined by..

Answer 20

total pulmonary ventilation; volume of air moved into and out of lungs each minute

Question 21

total pulmonary ventilation =

Answer 21

ventilation rate x tidal volume

Question 22

alveolar ventilation =

Answer 22

ventilation rate x (tidal volume - dead space)

Question 23

PO2 and PCO2 remains ______________ during quiet respiration

Answer 23

relatively constant

Question 24

As alveolar ventilation increases…. alveolar PO2 ________ and PCO2__________.

Answer 24

increases, decreases (and vice versa)

Question 25

Perfusion

Answer 25

blood flow

Question 26

perfusion is absent at the..

Answer 26

apex of lungs due to more negative intrapleural pressure (gravity)

Question 27

Pulmonary arterioles primarily influenced by….

Answer 27

decreasing O2 levels

Question 28

Bronchioles are sensitive to….

Answer 28

CO2 levels; dilating with increasing levels and constriction with decreasing levels