Download Respiratory System Outline

Respiratory System Outline
IV. Respiratory System - This is the system responsible for gas (oxygen and carbon dioxide) exchange.
A. Basic Anatomy
1. Nose/Nasal Cavity - As air enters the nose, dust and debris is trapped by mucus and
nostril hairs. Air is warmed and moisturized as well.
a. Smell receptors - Although part of your sensory system, smell
receptors are located at the top of the nasal cavity.
b. Sinuses - Mucus-lined cavities in the skull bones communicate with
the nasal cavity. They aid in filtering and moisturizing the air, as well
as being a cavity for resonance of sound. Unfortunately, infections and
allergies can cause sinuses to become filled with a lot of mucus, they
may become infected, and may even become clogged from draining into
your nasal cavity. This condition is termed sinusitis, and certainly
causes much discomfort.
2. Pharynx - Next, air passes into your throat.
3. Larynx - Next, air passes into your larynx. This is the structure that is the
opening into your airways and you may have referred to it as your "Adam's apple"
or your "voice box". It is made out of cartilage so that it is semi-rigid yet flexible
enough for you to be able to turn your neck.
a. Epiglottis - The epiglottis is an important component of the larynx. It
is a triangular flap that operates like a door opening and closing.
When swallowing, it closes so that you don't choke. When breathing or
speaking, it opens so that air can go back and forth in the airways.
Thought question: Why did your mother always tell you not to talk
while eating??
b. Vocal cords - Your elastic vocal cords are housed within the larynx.
They vibrate as air moves passed them. You have tiny muscles that can
shorten and lengthen the cords. Short and tightly stretched vocal cords
provide for high tones and long and loose vocal cords provide for low
tones.
Thought question: Why does the larynx enlarge as a boy goes through
puberty? Hint: The vocal cords lengthen and thus their "housing" must
enlarge.
4. Trachea - This is your windpipe. This airway is made of cartilaginous rings and
carries air from the larynx down towards your lungs. It is lined with cilia, or tiny
hairs, that function as an escalator to lift debris and dirt upward towards the
throat, rather than into the lungs.
5. Bronchi and Bronchioles - Once the trachea reaches the level of your lungs, it
branches into smaller and smaller branches that enter and spread out in each of
your lungs. The larger branches are called bronchi and the smaller ones are
bronchioles. The bronchi still have cartilage in their walls to prevent collapsing,
but the bronchioles do not have cartilage, and could collapse during an asthma
attack.
6. Lungs - You have two lungs within your chest cavity. The lungs are elastic and
filled with all of the bronchi and bronchioles. The bronchioles finally terminate on
millions of tiny air sacs called alveoli. These alveoli have very thin walls (one cell
layer) and are surrounded by numerous blood capillaries. THIS IS THE SITE
WHERE GAS EXCHANGE OCCURS.
B. Respiratory Physiology
1. Ventilation = Breathing
a. Inhalation=Inspiration - This is the process of bringing air IN to the
airways. The diaphragm (your breathing muscle located at the floor of
the chest cavity) lowers and the ribcage moves up and out. This
enlarges the chest cavity and the lungs and allows air to flow into the
lungs. You bring oxygen into your lungs from the atmosphere during
inhalation.
b. Exhalation=Expiration - This is the process of breathing OUT. As
the diaphragm raises, and your ribcage moves down and inward, air is
forced out of the lungs. You move carbon dioxide out into the
atmosphere during exhalation.
2. Diffusion - Diffusion occurs at the level of the alveoli and capillaries. Oxygen is
in high concentration in the alveoli after inhalation. It diffuses from the alveoli into
the bloodstream. Carbon dioxide is high in the bloodstream, as it is metabolic
"waste", and low in the alveoli. Therefore, carbon dioxide diffuses out of the
bloodstream and into the alveoli to be exhaled.
3. Gas transport in body ---As you recall from the blood section, the red blood cells
have hemoglobin that carries oxygen around the body in the bloodstream.
5. Respiratory Control Centers - Although you do have voluntary control over your
breathing muscles (they are skeletal muscle), you don't have to think about
breathing. The reason is, that the base of your brain, called your brainstem,
controls breathing. It tells you when to breathe, how rapidly and how deeply to
breathe.
C. Respiratory Pathology
1. Carbon monoxide poisoning - Carbon monoxide is a gas released from burning
combustible fuel such as a running car or a gas furnace. The poisonous nature of
carbon monoxide is that is readily attaches to hemoglobin, even faster than does
oxygen. Thus oxygen cannot attach to hemoglobin because it is clogged by the
carbon monoxide. The cause of death is lack of oxygen to your body tissues.
2. Laryngitis - Since the vocal cords are housed in the larynx, inflammation of the
larynx leads to voice loss.
3. Bronchitis -As the bronchi become irritated and inflamed, a deep and chronic
cough develops. It typically results in mucus being coughed up. Although a cold or
flu viral infection can move on down the airways and results in bronchitis, 75% of
all chronic bronchitis cases are due to cigarette smoking.
4. Emphysema - As bronchitis becomes chronic, it can result in inflammation of the
tiniest airways, the bronchioles. If these airways are inflamed for a long period of
time, they can scar closed, trapping any air in the alveoli. The alveoli then become
nonfunctional and eventually are destroyed. This change describes emphysema and
unfortunately is an irreversible change. Luckily, you have millions of alveoli, and
hopefully enough are functional to stay alive. This condition [sometimes called
chronic obstructive pulmonary disease (COPD)] is the fourth leading cause of
death in the U.S. Guess what the most common cause of emphysema is? 80% of the
cases are due to smoking.
5. Cancer - Lung cancer tends to be a difficult cancer to treat. The prognosis is
often poor, with estimates showing a 13% five year survival rate after lung cancer
is diagnosed. Again, about 83% of all cases of lung cancer are due to smoking.
This makes smoking the single major cause of cancer mortality in the U.S.!
6. Asthma - Most cases of asthma are due to allergies. Exposure to the allergens
(substances to which you are allergic such as pollen, molds, pet dander, peanuts,
strawberries...) results in increased mucus secretion in the airways and spasms of
the smooth muscle in the wall of the airways. Of course, the larger airways have
cartilage in their walls to prevent collapse. The bronchioles, however, have no
cartilage support in their walls and can collapse. As airways get smaller, the
person has difficulty breathing and makes a wheezing sound while breathing. It can
become a life-threatening situation when bronchioles constrict too much,
preventing oxygen from entering the alveoli. Medical inhalants contain medicines
that open the airways. If a person is unconscious from an asthma attack the
paramedic will administer epinephrine, or adrenaline, to open up the airways and
restore any heart or blood pressure complications.
7. Pneumonia - Normally, alveoli are filled with air. If they become infected and fill
with fluid, gas exchange becomes difficult or impossible. That is why pneumonia
can be a life-threatening illness. Most cases of pneumonia are caused by infection
deep within the lungs - in the alveoli.
You should now be able to answer the learning objectives on the Respiratory System.