Transcript Key Questions for Understanding Respiratory Physiology

Key Questions for Understanding
Respiratory Physiology
1. 4 Steps of Respiration
1. Pulmonary ventilation: also called
breathing; air moves into and out of the
lungs
2. External respiration: gas exchange
between the alveoli and the pulmonary
blood
3. Respiratory gas transport: oxygen and
carbon dioxide must be transported to and
from lungs and cells by the blood
4. Internal respiration: at systemic
capillaries, gas exchange occurs between
blood and tissue cells
2. Breathing depends on
volume changes occurring in
the thoracic cavity.
What are inspiratory muscles?
When the diaphragm and the external
intercostals contract, the size of the
thoracic cavity increases.
Since the lungs adhere tightly to the
thorax walls, they are stretched to
the larger size of the thorax
What causes the partial vacuum?
 As the volume of the lungs increases,
the gases in the lungs spread out,
which decreases the pressure of the
gas, producing a partial vacuum.
Why is expiration a passive
process?
 As the inspiratory muscles relax, the
ribcage descends and the lungs
recoil. This causes intrapulmonary
gases to flow out to relieve pressure
in the lungs. It requires no muscular
effort.
What are the effects of the decrease in
intrapulmonary volume?
 The gases in the lungs are forced
together, causing an increase in
pressure. To equalize the pressure
inside and outside the lungs, air flows
out.
What is pneumothorax?
 It is the presence of air in the
interpleural space.
 It is caused by a rupture of the
visceral pleura, often the result of a
chest wound.
What is normal tidal volume?
 It is the volume of air moved by
normal, quiet breathing.
 It averages about 500 mL, or 1 pint
What is the inspiratory reserve
volume?
 IRV is the amount of air that can be
taken forcibly over the tidal volume.
 It is between 2100 and 3200 mL
What is the residual volume?
 Residual volume is the amount of air
that remains in the lungs and cannot
be expelled. It normally equals 1200
mL.
What is vital capacity?
 Vital capacity is the total amount of
exchangeable air in the lungs. It
normally equals 4800 mL
 Tidal Volume (TV) + Inspiratory
Reserve Volume (IRV) + Residual
Volume (ERV) = Vital Capacity
Explain the difference between
external and internal respiration.
 External respiration is the actual
exchange of gases between the
alveoli and the blood
 Internal respiration is the gas
exchange process that occurs
between the systemic capillaries and
the tissue cells
13. Internal respiration, the exchange
of gases that takes place between the
blood and tissue cells is opposite to
what occurs in the lungs.
What is hypoxia?
 Hypoxia is inadequate oxygen
delivery to body tissues. It is easy to
recognize in fair-skinned people
because their skin and mucosae take
on a bluish cast (they become
cyanotic)
Why is carbon monoxide
dangerous?
 Carbon monoxide competes
vigorously with oxygen for the same
binding sites on hemoglobin. It often
displaces oxygen on the hemoglobin
molecule. Therefore, oxygen is
unable to be transported to the cells
of the body.