Respiratory system

1. By M.elkhatib

2.  Understanding the anatomy of the respiratory
system
 Understanding the physiology of the respiratory
system and the differences in paediatrics
 Understanding the mechanism of breathing and
gas exchange
 Clinical implications for paediatrics

4.  Respiration is achieved through the mouth, nose, trachea, lungs,
and diaphragm.
 The primary function of the respiratory system is to supply the
blood with oxygen in order for the blood to deliver oxygen to all
parts of the body. The respiratory system does this through
breathing. When we breathe, we inhale oxygen and exhale
carbon dioxide. This exchange of gases is the respiratory
system's means of getting oxygen to the blood.
 Molecules of oxygen and carbon dioxide are passively
exchanged, by diffusion, between the gaseous external
environment and the blood. The blood exchange process occurs
in the alveolar region of the lungs.

5. Oxygen enters the
respiratory system
through the mouth and
the nose.
As the oxygen enters, it
passes by the Olfactory
nerve which allows you
to smell.

6. The oxygen
then passes
through the
larynx
(where
speech
sounds are
produced)
and the
trachea
which is a
tube that
enters the
chest cavity.

7. In the chest cavity, the
trachea splits into two
smaller tubes called the
bronchi. Each bronchus
then divides again forming
the bronchial tubes.

9. The bronchial
tubes lead
directly into the
lungs where they
divide into many
smaller tubes
which connect to
tiny sacs called
alveoli.

10. The average adult's lungs
contain about 600 million of
these spongy, air-filled sacs that
are surrounded by capillaries.
The inhaled oxygen passes into
the alveoli and then diffuses
through the capillaries into the
arterial blood. Meanwhile, the
waste-rich blood from the veins
releases its carbon dioxide into
the alveoli. The carbon dioxide
follows the same path out of
the lungs when you exhale.

11. The diaphragm's job is to
help pump the carbon
dioxide out of the lungs and
pull the oxygen into the
lungs. The diaphragm is a
sheet of muscles that lies
across the bottom of the
chest cavity. As the
diaphragm contracts and
relaxes, breathing takes place.
When the diaphragm
contracts, oxygen is pulled
into the lungs. When the
diaphragm relaxes, carbon
dioxide is pumped out of the
lungs

12.  The respiratory system lies dormant in the human foetus during
pregnancy.
 At birth, the respiratory system becomes fully functional upon
exposure to air, although some lung development and growth
continues throughout childhood.
 Pre-term birth can lead to infants with under-developed lungs.
These lungs show incomplete development of the alveolar type II
cells, cells that produce surfactant.
 The lungs of pre-term infants may not function well because the
lack of surfactant leads to increased surface tension within the
alveoli.
 Thus, many of the alveoli collapse, such that no gas exchange
can occur within some or most regions of an infant's lungs, a
condition termed respiratory distress syndrome (RDS)

13.  Basic scientific experiments, carried out using cells from
chicken lungs, support the potential for using steroids as a
means of furthering development of type II alveolar cells. In
fact, once a pre-mature birth is threatened, every effort is
made to delay the birth, and a series of steroid shots is
frequently administered to the mother during this delay in
an effort to promote lung growth.
 Surfactant is now produed and manufactured. It is
administered to the pre-term infant after birth via an
endotracheal tube. Sometimes more then one dose is
required.

14.  Inhalation is initiated by the diaphragm and supported
by the external intercostal muscles. Normal resting
respirations are 10 to 18 breaths per minute, with a
time period of 2 seconds. During vigorous inhalation
(at rates exceeding 35 breaths per minute), or in
approaching respiratory failure, accessory muscles of
respiration are recruited for support. These consist of
sternocleidomastoid, platysma, and the scalene
muscles of the neck. Pectoral muscles and latissimus
dorsi are also accessory muscles.

15.  Under normal conditions, the diaphragm is the primary driver
of inhalation. When the diaphragm contracts, the ribcage
expands and the contents of the abdomen are moved
downward.
 This results in a larger thoracic volume and negative pressure
(with respect to atmospheric pressure) inside the thorax. As
the pressure in the chest falls, air moves into the conducting
zone. Here, the air is filtered, warmed, and humidified as it
flows to the lungs.
 During forced inhalation, as when taking a deep breath, the
external intercostal muscles and accessory muscles aid in
further expanding the thoracic cavity. During inhalation the
diaphragm contracts.

17. Exhalation is generally a passive process; however, active
or forced exhalation is achieved by the abdominal and the
internal intercostal muscles. During this process air is forced
or exhaled out.
The lungs have a natural elasticity: as they recoil from the
stretch of inhalation, air flows back out until the pressures in
the chest and the atmosphere reach equilibrium.
During forced exhalation, as when blowing out a candle,
expiratory muscles including the abdominal muscles and
internal intercostal muscles, generate abdominal and thoracic
pressure, which forces air out of the lungs.

19.  The major function of the respiratory system is gas
exchange between the external environment and the
circulatory system. This exchange facilitates
oxygenation of the blood with a concomitant removal
of carbon dioxide and other gaseous metabolic wastes
from the circulation.
 As gas exchange occurs, the acid-base balance of the
body is maintained as part of homeostasis. If proper
ventilation is not maintained, two opposing conditions
could occur: respiratory acidosis, a life threatening
condition, and respiratory alkalosis.

20.  Upon inhalation, gas exchange occurs at the alveoli, the tiny
sacs which are the basic functional component of the lungs. The
alveolar walls are extremely thin (approx. 0.2 micrometres).
These walls are composed of a single layer of epithelial cells
(type I and type II epithelial cells) close to the pulmonary
capillaries which are composed of a single layer of endothelial
cells.
 The close proximity of these two cell types allows permeability to
gases and, hence, gas exchange. This whole mechanism of gas
exchange is carried by the simple phenomenon of pressure
difference. When the atmospheric pressure is low outside, the air
from lungs flow out. When the air pressure is low inside, then the
vice versa.

21.  Primary function is to obtain oxygen for use by
body's cells & eliminate carbon dioxide that cells
produce
 Pathway of air: nasal cavities (or oral cavity) >
pharynx > trachea > primary bronchi (right & left) >
secondary bronchi > tertiary bronchi > bronchioles
> alveoli (site of gas exchange)