Pulmonary Ventilation

Question 1

lungs can be contracted or expanded in two ways which are

Answer 1

(1) by downward and upward movement of the diaphragm to lengthen or shorten the chest cavity, and (2)
by elevation and depression of the ribs to increase and
decrease the anteroposterior diameter of the chest cavity

Question 2

quite breathing is accomplished by

Answer 2

movement of diaphragm

Question 3

during inspiration diaphragm moves?

Answer 3

pulls the lungs downwards

Question 4

during expiration the diaphragm?

Answer 4

, the diaphragm simply relaxes, and the

elastic recoil of the lungs, chest wall, and abdominal structures compresses the lungs and expels the air

Question 5

during inspiration the rib cage moves?

Answer 5

forwards and upwards away from the sternum ( increasing the anteroposterior thickness of chest by 20%)

Question 6

the muscles that elevate

Answer 6

muscles of inspiration (opposite are muscles of expiration)

Question 7

The most important muscles that raise the rib cage

are

Answer 7

external intercostals, but others that help are the
(1) sternocleidomastoid muscles, which lift upward on the
sternum; (2) anterior serrati, which lift many of the ribs;
and (3) scaleni, which lift the first two ribs

Question 8

The muscles that pull the rib cage downward during

expiration are mainly

Answer 8

(1) the abdominal recti, which have
the powerful effect of pulling downward on the lower ribs
at the same time that they and other abdominal muscles
also compress the abdominal contents upward against the
diaphragm, and (2) the internal intercostals

Question 9

tell the contraction and relaxation of intercoastal muscles and external coastal muscles during inspiration

Answer 9

external intercoastal muscles contract
inter intercoastal muscles relax
ribs move forward (elevate)

Question 10

pleural pressure

Answer 10

Pleural pressure is the pressure of the fluid in the thin

space between the lung pleura and the chest wall pleura.

Question 11

The normal

pleural pressure at the beginning of inspiration is

Answer 11

-5 cm of h2o

Question 12

During normal inspiration, expansion of the chest cage
pulls outward on the lungs with greater force and creates
more negative pressure, to an average of abou

Answer 12

-7 cm of h20

Question 13

whne the glottis is open what is the pressure inside the lungs?

Answer 13

the pressures in all parts of the
respiratory tree, all the way to the alveoli, are equal to
atmospheric pressure, which is considered to be zero reference pressure in the airways—that is, 0 centimeters
of water pressure.

Question 14

the cause inspiration the pressure falls inside the alveoli to

Answer 14

-1 cm of h20 (makes 0.5 liter of o2 to flow inwards into the lungs)

Question 15

transpulmonary pressure

Answer 15

transpulmonary pressure is the pressure difference between that in the alveoli and that on the outer surfaces of the lungs (pleural pressure), and it is a measure
of the elastic forces in the lungs that tend to collapse the lungs at each instant of respiration, called the recoil pressure.

Question 16

what is lung compliance

Answer 16

a measure of the lung expandability

It refers to the ability of the lungs to stretch and expand

Question 17

The total compliance of both lungs together

Answer 17

200 milliliters of air

per centimeter of water transpulmonary pressure.

Question 18

The characteristics of the compliance diagram are
determined by the elastic forces of the lungs. These forces
can be divided into two parts:

Answer 18

1. elastic forces of lung tissue
   2) elastic forces caused by surface tension of the
   fluid that lines the inside walls of the alveoli and other lung
   air spaces.

Question 19

if the lungs are filled with saline what happes

Answer 19

there is no interaction between the air and the alveolar fluid so there is no surface tension present

Question 20

surface tension elastic force

Answer 20

the nect effect is to cause an elastic contractile force of the entire lung

Question 21

function of surfactant

Answer 21

reduces the surface tension of water molecules

Question 22

It is

secreted

Answer 22

type II alveolar epithelial cells,

Question 23

most important component of surfactant

Answer 23

phospholipid dipalmitoyl phosphatidylcholine,

surfactant apoproteins, and calcium ions.

Question 24

dipalmitoyl phosphatidylcholine,

surfactant apoproteins works how

Answer 24

They perform this function by not dissolving uniformly
in the fluid lining the alveolar surface. Instead, part of the
molecule dissolves while the remainder spreads over the
surface of the water in the alveol

Question 25

respiratory distress syndrome of the newborn.

Answer 25

the less the radius of the alveoli the more will be the alveolar pressure
so premature infants have alevoli radii less than 25% of that an adult and have no production of surfactants (starts at 7-6th month of gestation or later) so their lungs have more tendency to collapse

Question 26

compliance of lungs and thorax

Answer 26

110 ml/cm of H2O

Question 27

Thus,
under resting conditions, the respiratory muscles normally
perform “work” to cause ……… and why?

Answer 27

inspiration because during inspiration the respiratory muscles contract and while expiration its recoil effect of the lungs, chest wall and other muscles

Question 28

The work of inspiration can be divided into three fractions:

Answer 28

(1) that required to expand the lungs against the lung
and chest elastic forces, called compliance work or elastic
work; (2) that required to overcome the viscosity of the lung
and chest wall structures, called tissue resistance work; and
(3) that required to overcome airway resistance to movement of air into the lungs, called airway resistance work.

Question 29

tidal volume

Answer 29

is the volume of air inspired or
expired with each normal breath; it amounts to
about 500 milliliters in the average adult male.

Question 30

The inspiratory reserve volume i

Answer 30

e is the extra volume
of air that can be inspired over and above the
normal tidal volume when the person inspires
with full force; it is usually equal to about 3000
milliliters.

Question 31

The expiratory reserve volume

Answer 31

is the maximum
extra volume of air that can be expired by forceful
expiration after the end of a normal tidal expiration;
this volume normally amounts to about 1100
milliliters.

Question 32

The residual volume

Answer 32

is the volume of air remaining
in the lungs after the most forceful expiration; this
volume averages about 1200 milliliters

Question 33

inspiratory capacity

Answer 33

equals the tidal volume
plus the inspiratory reserve volume. This capacity is
the amount of air (about 3500 milliliters) a person
can breathe in, beginning at the normal expiratory
level and distending the lungs to the maximum
amount.

Question 34

The functional residual capacity

Answer 34

expiratory reserve volume plus the residual volume. This
capacity is the amount of air that remains in the
lungs at the end of normal expiration (about 2

Question 35

vital capacity

Answer 35

expiratory reserve volume plus the residual volume. This
capacity is the amount of air that remains in the
lungs at the end of normal expiration (about 2

Question 36

The total lung capacity

Answer 36

is the maximum volume to
which the lungs can be expanded with the greatest
possible effort (about 5800 milliliters); it is equal to
the vital capacity plus the residual volume

Question 37

4 pulmonary capacities

Answer 37

inspiratory capacity
function residual capacity
vital capacity
total lung capacity

Question 38

The minute respiratory volume is

Answer 38

s the total amount of new
air moved into the respiratory passages each minute and
is equal to the tidal volume times the respiratory rate per
minute

Question 39

what is normal respiratory volume

Answer 39

Therefore, the minute respiratory volume averages about 6 L/min.

Question 40

The ultimate importance of pulmonary ventilation

Answer 40

is to continually renew the air in the gas exchange areas of the lungs, where air is in proximity to the pulmonary blood. These areas include the alveoli, alveolar sacs, alveolar ducts, and respiratory bronchioles.

Question 41

alveolar ventilation

Answer 41

The rate at which new

air reaches these areas alveoli, alveolar sacs, alveolar ducts, and respiratory bronchioles.

Question 42

dead space

Answer 42

Some of the air a person breathes never reaches the gas
exchange areas but simply fills respiratory passages where
gas exchange does not occur, such as the nose, pharynx,
and trachea. This air is called dead space air because it is
not useful for gas exchange.

Question 43

normal dead space volume

Answer 43

150ml

Question 44

physiological dead space

Answer 44

the non functional alveoli are counted in the anatomical dead space then it is called the physiological dead space

Question 45

Alveolar ventilation per minute

Answer 45

is the total volume of new
air entering the alveoli and adjacent gas exchange areas
each minute.

Question 46

resistance to airflow in bronchial tree is usually caused by

Answer 46

larger bronchiole than smaller because there are many small bronchioles comparatively to larger ones

Question 47

In some disease conditions, the smaller bronchioles play

a far greater role in determining airflow resistance because

Answer 47

(1) muscle contraction in their walls, (2) edema occurring
in the walls, or (3) mucus collecting in the lumens of the
bronchioles

Question 48

sympathetic stimulation of bronchiole tree

Answer 48

norepinephrine and epinephrine has a direct affect on the bronchiole causing them to dilate

Question 49

parasympathetic effect

Answer 49

acethylcholine causes the brioncholes to constrict

in asthma the parasympathetic effect worsens the situation

Question 50

drug the blocks the effect of acytelcholine

Answer 50

atropine

Question 51

Sometimes the parasympathetic nerves are also activated by reflexes that originate in the lungs which are

Answer 51

irritation of the epithelial membrane of
the respiratory passageways, initiated by noxious gases,
dust, cigarette smoke, or bronchial infection. Also, a bronchiolar constrictor reflex often occurs when microemboli
occlude small pulmonary arteries.

Question 52

local secretory factors causing contraction in bronchiole are

Answer 52

histamine and slow reacting substance of anaphylaxis released during allergic reactions like asthma causes constriction or cause’ of some irritant like SO2 or acidic elements in smog

Question 53

cough reflex

Answer 53

The bronchi and trachea are so sensitive to light touch that
slight amounts of foreign matter or other causes of irritation initiate the cough reflex. The larynx and carina (i.e., the point where the trachea divides into the bronchi) are especially sensitive, and the terminal bronchioles and even the alveoli are sensitive to corrosive chemical stimuli
such as sulfur dioxide gas or chlorine gas. Afferent nerve
impulses pass from the respiratory passages mainly through the vagus nerves to the medulla of the brain