Respiratory Mecanics Of Pulmonary Ventilation

Front 1

what is ventilation?

Back 1

mechanical process by which the lung parenchyma is filled and eptied

Front 2

how is ventilation accomplished?

Back 2

skeletal muscle activity accomplishes the pumping action, which is active during the inspiratory and passive during expiratory phases of normal tidal breathing in mammals

Front 3

How do the mechanics of lung expansion and contraction occur?

Back 3

(1) caudal/cranial movement of diaphragm (2) elevation/depression of the ribs

Front 4

illustrate inspiration and expiration

Front 5

what is quiet breathing a function of?

Back 5

primarily diaphragmatic movement

Front 6

what occurs during inspiration in quiet breathing?

Back 6

diaphragm conracts & lungs expand caudally

Front 7

what occurs during expiration in quiet breathing?

Back 7

diaphragm relaxes and gas is expelled by the elastic recoil of lungs and chest wall

Front 8

what is heavy breathing the result of?

Back 8

the incorporation of auxiliary muscles of inspiration (to the diaphragmatic movement)

Front 9

what occurs during inspiration in heavy breathing?

Back 9

Inspiration relies on (1) expanding the rib cage (2) increases volume of thoracic cavity by 20% (3) muscles that raise rib cage called muscles of inspiration (a) external intercostals: contract between ribs (b) primary serratus dorsalis cranialis: lift many of the ribs (c) dorsal scalenus: lifts more cranial ribs

Front 10

what occurs during expiration in heavy breathing?

Back 10

(1) elastic recoil forces (2) normally expiratory muscles are NOT actively contracting, except during 'forced' expiration such as extreme exercise or airway obstruction; then abdominal muscles contact, pull abdominal contents against diaphragm (3) expiratory muscles (a) rectus abdominus muscles: compress abdominal contents twoard the diaphragm (b) internal intercostal muscles

Front 11

what is the single most important respiratory muscle?

Back 11

diaphragm

Front 12

what causes movement of air?

Back 12

(1) pleural pressure (2) alveolar presure (3) transpulmonary pressure

Front 13

what does PPL stand for?

Back 13

pleural pressure

Front 14

what does PA stand for?

Back 14

alveolar pressure

Front 15

what does PTP stand for?

Back 15

transpulmonary pressure

Front 16

what is pleural prssure?

Back 16

PPL, pressure inside pleural space

Front 17

what is alveolar pressure?

Back 17

PA, pressure in alveoli (= atomospheric if glottis open)

Front 18

what is transpulmonary pressure?

Back 18

PTP, PA-PPL, normally PA > PPL

Front 19

what is elastic recoil?

Back 19

an attribute of the lungs that describes how they are elastic like a ballon and that without a force to keep them inflated, they deflate

Front 20

what is elasticity due to?

Back 20

elastin & collagen fibers in the lung tissue

Front 21

how are lungs positioned in the thoracic cavity?

Back 21

float in it suspended from the mediastinum having 'grown into the pleural sac

Front 22

what are the lungs covered by?

Back 22

a layer of pleura (which is intimately attached to the lung)

Front 23

what is the chest wall coverd by?

Back 23

a layer of pleura (which is intimately attached to the lung)

Front 24

what is the potential space between the lung and chest wall pleural layers filled with?

Back 24

a thin layer of pleural fluid

Front 25

where does pleural fluid come from?

Back 25

mesothelial cells secrete in into the potential space as pleura is stretched

Front 26

the continuous suction of excess fluid into lymphatic channels causes what?

Back 26

a slightly negative pleural pressure holding the lungs and pleura next to the thoracic wall

Front 27

what is the main force responsible for negative pleural pressure, even during expiration?

Back 27

elastic recoil

Front 28

describe pleural pressure?

Back 28

negative pressure in the pleural space due to the elastic recoild forces of the lungs and thoracic wall in opposing direction

Front 29

what are the values of the pleural pressure during respiration?

Back 29

(1) resting pressure = -4cm H2O (2) inspiration = -6cm H2O (3) expiration = -4cm H2O

Front 30

what does the decrease from -4 to -6 cm H2O of pleural pressure is the force that evokes what?

Back 30

expansion of the lung parenchyma during inhalation

Front 31

what is alveolar pressure equal to with the glottis open?

Back 31

pressure throughout the entire respiratory tree equals atmospheric pressure

Front 32

how are all physiological pressures expressed?

Back 32

relative to a zero value reference of atmospheric pressure (which is assigned 0 regardless of the ambient baromteric pressure)

Front 33

what are the values of alveolar pressure during respiration?

Back 33

(1) resting pressure = 0cm H2O (2) inspiration = -1cm H2O (3) expiration = +1cm H2O

Front 34

describe transpulmonary pressure?

Back 34

pressure difference between alveoli and outer surface of the lungs (pleural pressure) which is equal to the elastic forces of lung that want to collapse, also called recoil pressure

Front 35

what does PTP =?

Back 35

PA - PPL

Front 36

what is recoil pressure?

Back 36

the elastic forces of lung that want to collapse it (equal to transpulmonary pressure)

Front 37

what is another term for alveolar pressure?

Back 37

intrapulmonary presure

Front 38

what is another term for plueral pressure?

Back 38

intrapleural pressure

Front 39

what maintains lung inflation?

Back 39

transpulmonary pressure

Front 40

what happens if PTP is neutralized?

Back 40

lung deflation (pneumothorax)

Front 41

diagram the relationships between the alveolar pressure, pleural pressure, and transpulmonary pressure

Front 42

diagram the cyclic diaphragmatic activity upon alveolar, intrapleural, and transpulmonary pressures during tidal breathing

Front 43

when does flow occur?

Back 43

whenever there is a pressure difference between the proximal and distal ends of a system

Front 44

what is the direction of flow?

Back 44

always toward the area of lower pressure

Front 45

Illustrate the pressure gradients created by diaphragmatic contraction and relaxation during normal tidal breathing

Front 46

Illustrate the air flow forces during quiet breathing at rest

Front 47

Illustrate the air flow forces during quiet breathing during inspiration

Front 48

illustrate the air flow forces during quiet breathing during expiration

Front 49

what are the types of pneumothorax?

Back 49

open or closed

Front 50

what is a closed pneumothorax?

Back 50

a dicontinuity of the lung parenchyma, without an opening between the chest and atmosphere

Front 51

what are some causes of closed pneumothorax?

Back 51

(1) rib fractures (2) ruptured bulla

Front 52

what is an open pneumothorax?

Back 52

a puncture wound to the chest; aka sucking chest wound

Front 53

Illustrate the pressures in a normal resting thorax pressures

Front 54

illustrate the pressures in a pneumothorax

Front 55

what is compliance of lungs?

Back 55

volume change per unit transpulmonary pressure change; an indicator of how distensible the lung is

Front 56

the more compliant a structure is, the BLANK it is

Back 56

less stiff

Front 57

what are the components of compliance?

Back 57

(1) elastic forces of lung tissue (2) forces from surface tension

Front 58

what are the elastic forces of lung tissue in compliance?

Back 58

(1) elastin and collagen fibers interwoven among the lung parenchyma (2) in deflated lungs: fibers are contracted and kinked (3) in expanded lungs: fibers become stretched and unkinked with elastic potential energy for returning the lung to its resting volume

Front 59

what are the forces from surface tension in compliance?

Back 59

(1) fluid on inner surfaces of alveoli also have surface tension, contraction of the H2O surface attempts to force air out and collapse alveoli (2) surfactant decreases surface tension of water, helps prevent alveolar collapse (atelectasis)

Front 60

what is atelectasis?

Back 60

alveolar collapse

Front 61

what are the characteristics of surfactatnt in lungs?

Back 61

(1) reduces surface tension (2) secreted by type II alveolar epithelial cells: cells are bout 10% of alveolar surface (3) surfactant is phospholipid-containing fluid (4) as alveolar size decreases surface tension pressure increases, but surfactant concentration increases as it is spread over a smaller surface area so the surface tension of water is neutralized

Front 62

what disease states affect lung compliance?

Back 62

(1) decreased compliance (2) increased compliance

Front 63

what causes decreased compliance in lungs?

Back 63

alveolar edema (prevents inflation of alveoli); fibrosis

Front 64

what causes increased compliance in lungs?

Back 64

old age; emphysema