Respiratory System
Chapter 9
Respiratory System Functions



To get oxygen into the red blood cells
To release carbon dioxide from the blood
“pulmonary”- refers to the lungs
Respiration
Inhalation- air enters nose and mouth
 Air gains heat and moisture as it enters the lungs
 filtered by nose hairs and cilia within the trachea
to remove contaminants
Exhalation- warm air cools as it leaves the bodycondenses on a cold day and looks like smoke
Pathway of air
Nose- has odor receptors, hairs filter air, tear ducts
and sinuses drain here
Nasopharynx- just above the back of throat
Pharynx- connects mouth and nasal passages
Tonsils- right behind tongue- part of the immune
system
Into the windpipe
Glottis- opening from pharynx to trachea
Epiglottis- flap of tissue that covers the glottis when you
swallow so food/liquid doesn’t enter your lungs
Larynx- just below glottis- has vocal cords
Trachea- windpipe- has cartilage rings- similar to rings on
a vacuum cleaner hose- prevent the trachea from
collapsing and being sucked shut when you inhale
Bronchi- forks of trachea that lead to the lungs
The lungs




Bronchi fork into smaller bronchioles
bronchi and bronchioles are surrounded by
smooth muscles- they can contract and cause
asthma- difficulty breathing
end in tiny air sacs called alveoli
The lungs are located in the thoracic cavity of
the upper chest
Alveoli




Made of simple squamous epithelium
surrounded by tiny capillaries
gas exchange takes place here
All these tiny sacs increase surface area for gas
exchange- lungs have 60m2 of area
lined with surfactant that prevents them from
sticking closed by h-bonding of water
Mechanics of breathing




The thoracic cavity is sealed so when the
diaphragm muscle on the bottom contracts, the
cavity gets bigger
the vacuum that this creates pulls the lungs open
and air rushes in
diaphragm relaxes- lungs expel the air because
they are elastic
damage to this cavity= loss of vacuum seal=
lung collapse
Other muscles
External intercostal muscles- expands rib cage to
help with inhalation
Internal intercostal muscles- cause rib cage to get
smaller= forced exhalation
 Contraction of abdominal muscles can also
force more air out of the lungs by pushing up
against the diaphragm
Control of breathing
Medulla- control center- generates continuous
impulses to stimulate diaphragm
Chemoreceptors sensing carbon dioxide and
acidity in the carotid (neck) arteries and the aorta
can increase rate
Gas exchange


Carbon dioxide is carried in blood plasma as
bicarbonate
Hemoglobin in red blood cells picks up oxygen
and changes to oxyhemoglobin
In tissues



The oxyhemoglobin drops off oxygen
Carbon dioxide enters red blood cells and is
then converted into bicarbonate
The bicarbonate leaves the red blood cell and
enters the plasma
Upper Respiratory Infections
Sinusitis- infection of the sinuses- hollow areas of
the skull- most drain into the nose
 Results in clogged drains and pressure build up
 Pain usually increases as you lean forward
 Treated with spray decongestants, breathing in
water vapor during a hot shower may loosen the
clogs and provide some relief
Otitis media




Bacterial infection of middle ear
bacteria from throat get in through auditory tube
Treatment= antibiotics
tubes sometimes are inserted to drain fluid
Tonsilitus




Tonsils become inflamed and enlarged
Tonsils normally fight pathogens
If severely swollen, they can interfere with
breathing so they are sometimes removed
immune system is impaired if removed
laryngitis


Infection of larynx
Causes hoarseness
Lower respiratory diseases
Acute bronchitus- a bacterial infection of the
bronchi after a viral Upper respiratory infection
 dry cough becomes a deep cough that
expectorates mucus and pus
Pneumonia- viral or bacterial infection of part of
the lungs- alveoli fill with fluid- reduced gas
exchange
 usually occurs after the flu
 fever, headache, chest pain
More Lower Resp. Infections
Pulmonary tuberculosis- bacterial
 Bacteria are encased by lung cells- called
tubercules
 skin test reveals exposure
 some people can recover naturally
 sanatoriums- quarantine areas
 Treatment= antibiotics- but now some strains
are partially resistant
Other lung disorders
Pulmonary fibrosis- the inhalation of dust and
fibers such as asbestos causes fibrous connective
tissue to build up in the alveoli
 the elasticity of the lungs is reduced and they
cannot inflate properly
 poor respiration
Chronic bronchitus




Airways are inflamed and filled with mucus
Cleaning cilia have been lost
more prone to infection
caused by smoking and exposure to pollutants
Emphysema




Alveoli are stretched out and damaged so that
less surface area is available for gas exchange
chronic
lungs aren’t as elastic and don’t exhale all the air
present- inefficient because lots of stale air
remains in the lungs
supplemental oxygen is sometimes needed
Asthma
Wheezing, breathlessness and coughing
 affects bronchi and bronchioles
 when airways are exposed to an irritant, the
smooth muscle spasms and constricts them
 triggered by immune system
Treatment- inhalers to stop spasms and dilate
airways

Lung cancer



Steps- caused by smoking and other chemicals1. thickening of cells in airway, 2. cilia are lost, 3.
nucleus becomes abnormal (damaged DNA), 3.
cancerous cells break free and spread to other
parts of the body
surgery can remove the affected part of the lung
if it the cancer hasn’t spread
also caused by second hand smoke