Download Intro to Respiration

Title: The Respiratory System
1- The body’s cells continually uses oxygen to carry out all of their metabolic
activities. At the same time these activities release carbon dioxide that has to
be removed from the body. Excess carbon dioxide acidifies the body and is
toxic to cells. The cardiovascular system and respiratory system work
synergistically to move oxygen into the body, circulate it around and remove
carbon dioxide. The respiratory system allows a mechanism for the exchange
of these two gases. Failure will result in the breakdown of homeostasis and
either death from suffocation (oxygen starvation) or from the build up of
toxic waste (carbon dioxide)
2- Anatomy of the Respiratory System
a- The respiratory system consists of the nose, pharynx (throat), larynx
(voice box), trachea (wind pipe), bronchi and lungs
b- Its parts are classified as either structural or functional
1- Structurally the respiratory system consists of two parts
ab-
2- Functionally the respiratory system also consists of two parts
ab-
3- Portions of the Respiratory Tract
a- The Nose – The nose contains both an external portion and an
internal portion housed within the skull.
b- The external portion contains a supporting network of both
bone and hyaline cartilage covered by muscle and skin and
lined with a mucus membrane
c- The cartilaginous portion of the skull consists of septal
cartilage, which forms the anterior portion of the nasal septum.
The lateral nasal cartilage is found inferior to the nasal bones
and the alar cartilage, which forms the walls of the nostrils.
d- The external nares or nostrils are the openings to the outside
of the body. The internal nares connects to the pharynx
e- The walls of the internal nose are formed by the ethmoid,
maxillae, lacrimal, palatine and inferior conchae bones
f- The nose has three functions
1- Warming, moistening and filtering incoming air
2- Detecting olfactory (smell) stimuli
3- Modifying speech vibrations as they pass through
the large hollow resonating chambers (resonance
refers to prolonging, amplifying or modifying a
sound produced by a vibration)
g- Mucus particles secreted by the goblet cells moistens the air
and traps dust particles. Drainage from this area helps to
moisten the air. The cilia in the nose move the trapped
particles toward the pharynx and which point they can be
swallowed or spit out, thus removing the particles from the
respiratory tract.
The Respiratory System
1- The Pharynx – Also known as the throat functions as a passageway for food
and air, provides a resonance chamber for sound (speech), houses the tonsils
and participates in immunological reactions against foreign invaders
a- Children who have had their tonsils removed get many more ear
infections than children who still have them
b- The pharynx is subject to lots of abrasions from food and other materials,
hence the epithelial lining is rapidly replaced in this region
2- The Larynx – also known as the voice box it a short passageway that connects
the pharynx with the trachea.
a- The thyroid cartilage (Adam’s apple) consists of hyaline cartilage and
makes up the anterior portion of the larynx. The cartilage gives it is
characteristic triangular shape
b- The Adam’s apple is typical larger in males as it is influenced by male sex
hormones during puberty
c- Why are males voiced deeper?
d- The epiglottis is a large leaf shaped structure attached to the upper
portion of the larynx. The unattached portion acts like a trap door
preventing food from passing into the trachea.
e- The Glottis lies below the epiglottis and contains the vocal cords. When
you cough the glottis stays closed until the pressure reaches a certain
point and then it opens allowing the forceful expulsion of air.
f- The cricoid cartilage is a ring of hyaline cartilage and the inferior end of
the larynx. It can be felt from the outside and is a landmark for
performing a tracheotomy.
3- Trachea – Also known as the windpipe, is a tubular passageway about 5
inches long and 1 inch in diameter. The trachea divides into the right and left
bronchi as it enters the lung
a- The walls of the trachea are lined with mucus and held in place by
cartilage. These cartilaginous rings help to keep the trachea open during
inhalation
b- The walls are filled with mucus producing goblet cells that help to protect
the lungs against dust and other foreign particles.
c- Remember the muco-ciliary elevator is damaged by nicotine. This leads to
the characteristic smokers lung. If you stop smoking the cilia will repair
themselves and the coughing will go away.
4- Bronchi – The trachea divides into the right and left primary bronchus which
goes into the right lung and the left lung respectively.
a- The right bronchus is shorter more vertical and wider than the left. As a
result swallowed objects are more likely to get stuck here.
b- The area where the bronchi split and enter the lungs is called the carina.
It is very sensitive and is often the area that triggers the cough reflex
c- Once in the lungs the primary bronchi divide into the secondary bronchi.
One goes into each lobe of the lung (right three and left two – Superior,
middle and inferior and superior and inferior)
d- The secondary bronchi further divide into the tertiary bronchi then into
the bronchioles and finally ending with the terminal bronchioles.
Collectively this is referred to as the bronchial tree.
Title: Lung Measurements
1- At rest a healthy lung breathes about 12X/ minute, or once for about every 56 heart beats.
a- With each inhalation (breathing in) or exhalation (breathing out)
about 500 mls of air is moved in and out of the lungs
b- The volume of one breath is called the tidal volume (Vt)
c- The minute ventilation (MV) is the total volume of air exchanged in
and out in one minute. It is calculated by multiplying the breathing
rate X the tidal volume
d- About 70% (350mls) of each breath makes it down to the alveoli. The
remaining 30% (150mls) stays in the nose, trachea, bronchi and
upper lobes of the lungs
1- The anatomic dead space refers to areas in the respiratory tract
not in the alveoli. If the air is not in the alveoli it is not exchanging
gases and therefore not serving a purpose.
2- An interesting factoid is that the anatomic dead space for each
individual is about equal in mls to the ideal weight of the person in
question, i.e., if your ideal weight is 135 pounds you will have an
anatomic dead space of about 135 ml.
3- The alveolar air rate is the amount of air in the alveoli times the
beats per minute
4- The inspiratory reserve volume (IRV) is the maximum amount
of air that you can take in after several deep breaths. This is
usually about 3500ml in males and 1900ml in females.
5- The expiratory reserve volume (ERV) is obtained after a
maximal expiration directly after a maximum intake of air. The
ERV is usually about 1200ml in males and 700mls in females
6- The residual volume (RV) is the amount of air remaining in the
non-collapsible alveoli after a maximal expiration. The residual
volume is about 1200ml in males and 1100ml in females
7- Calculating lung capacity. Lung capacities are combinations of
specific lung volumes
a- Inspiratory capacity – is the sum of the tidal volume (Vt) and
the inspiratory reserve volume (IRV) approximately 500ml
+ 3100ml = 3600ml in males and 500ml + 1900ml = 2400ml
in females
b- Functional residual capacity (FRC) is the sum of the residual
volume (RV) and the expiratory reserve volume (ERV). The
FRC = 1200ml + 1200ml = 2400mls in males and 1100ml +
700ml
= 1800ml in females
c- The Vital Capacity or the maximum amount of air that can
be exhaled after maximal inhalation is the sum of the IRV + Vt
+ ERV these equal about 4800ml in males and 3100ml in females
d- Total Lung Capacity is the total of the vital capacity plus the
residual volume (RV) this equals approximately 4800ml +
1200mls = 6000ml in males and 3100ml + 1100 ml = 4200ml in
females
e- Diagram