Transcript The_Respiratory_System

The Respiratory System
Respiratory system
• A series of passages that filter
incoming air and transport it
from outside the body into the
lungs, and numerous air sacs in
which gas exchange occurs.
• Oxygen must be supplied to all
the body’s tissues and carbon
dioxide removed
Divided into 2 parts:
1. Upper Respiratory Tract- nose,
nasal cavity, pharynx, larynx,
paranasal sinuses.
• All organs superior to larynx.
2. Lower respiratory tracttrachea, bronchiole tree, lungs
Upper Respiratory Tract
The Nose•
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2 sets of openings, ext. nares,
(nostrils) and int. nares.
Divided by a septum (hyaline
cartilage)
Lined with str. Squamous epith.
Contains hairs
Function is to filter debris from the air.
The Nasal Cavity
• Chamber posterior to the nose.
• Maze of bones lined with
mucous membrane.
strat. squamous- pseudostratified.
• function is to warm, humidify,
and clean air breathed in.
Olfactory plate- chemoreceptors
located here that enable us to
smell.
• Located on a bone called the
cribiform plate.
Paranasal Sinuses
• Hollow, mucous membrane
lined bony cavities, named for
the bones they reside in.
• 2 frontal
• 2 maxillary
• Several sphenoid
• Several ethmoid
• function- to reduce the weight
of the skull and affect the
resonant quality of the voice.
Pharynx
• Carries air to the larynx on way
to the lungs.
• Dual function with digestive
system
Divided into 3 areas:
1. nasopharynx- uvula, flap of
tissue that covers the opening
to the nasopharynx when
swallowing. Palatine tonsils
2. Oropharynx- pharyngeal
tonsils
3. Laryngopharynx- space
between the oropharynx and
the larynx
Laryngopharynx
• Glottis- opening to the
trachea in which air passes
to the trachea
• Epiglottis- cartilage flap
that covers the trachea
when swallowing.
The Larynx
• An enlargement of the airway,
composed of cartilage plates.
thyroid and cricoid plates
• Contains 2 structures
1. False vocal cords-muscles that
protect the vocal cords and close the
larynx when swallowing
2. True vocal cords-elastic tissue with
muscles attached.
• Sound is produced by forcing air over
the cords.
• The vibration of the cords produces
the sounds.
• Sounds can be changed by changing
the shape of the larynx, mouth, lips,
and tongue
• Pitch is controlled by changing the
tension of the cords
• Loudness is created by the amount
of air being forced over the cords
Lower Respiratory Tract
Trachea-windpipe, 1” in
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diameter, 5” to 7 “ long.
Extends from the larynx to
bronchi which splits into the
Left and Right lung.
Lined with pseudostratified
epith. With many mucous
producing goblet cells.
This continues to filter air
leading to the lungs
Cilia moves particles trapped
upward to be expelled
Supported by about 2 cartilage
C-shaped pieces
Gaps are filled with smooth
muscle and FCT.
Prevent collapsing of trachea
Bronchial Tree
• Trachea divides into the Left
and right bronchi.
• Right bronchus is larger and
more vertical
• They are supported by cartilage
plates
• Lined with pseudostratified epi.
• Each bronchi enters the lungs
and branch into smaller
bronchioles.
• Bronchioles branch into sec.
bronchioles
• Secondary bronchioles branch
into alveolar ducts.
• Lining has changed from
pseudo to simple squamous epi
Bronchiole Tree (cont)
• There has been a transition
from cartilage rings to plates to
no support.
• These series of increasingly
smaller tubes serve as
passageways for air to enter
and exit the lungs.
Alveoli
• Functional unit of the respiratory
system.
• Site of gas exchange
• Groups of small microscopic air
sacs.
• Composed of simple squamous
epith.
• Surrounded by blood capillaries.
• Site of external respiration
• Oxygen enters blood to rbc,
carbon dioxide comes off rbc and
exits into alveolus to be exhaled.
• 300 million alveoli per lung.
• 70-80 sq meters surface area.
Size of a tennis court.
Alveoli (cont)
The Lungs
• 2 cone shaped organs.
• Left has 2 lobes, superior and
inferior
• Right has 3 lobes, superior, middle,
and inferior
• The external surface of the lungs
and the inner surface of thoracic
cavity lined with pleura.
• Visceral pleura on lungs
• Parietal pleura inner surface of
thoracic cavity
• Pleural space between the 2
surfaces.
• Alveoli of the lungs and capillaries
of the pulmonary circulation work
together to serve as highly efficient
gas exchangers. (diffusion)
Mechanics of Breathing
• Breathing is a mechanical
process of taking air into and
out of the lungs.
Respiration is the exchange of
gases:
External respiration-between rbc’s
and alveoli of lungs.
Internal respiration- between red
blood cells and the cells of the
various tissues of the body.
Composition of gases of the Earth’s atmosphere.
Nitrogen 78%
Oxygen 21%
Carbon Dioxide .03%
Rare gases .9 %
Exhaled Air:
Nitrogen 78%
Oxygen 18%
Carbon Dioxide 3%
Rare gases .9%
Inspiration-Inhalation
• Caused by the contraction of the
diaphragm.
• Moves downward increasing the
volume of the thoracic cavity
therefore reducing its pressure.
(Boyle’s Law)
Major Events of Inspiration:
1. nerve impulses are carried by the
phrenic nerve to the diaphragm
causing it to contract.
2. As the diaphragm moves downward,
the size of the thoracic cavity is
increased.
3. At the same time, the external
intercostal muscles may contract ,
raising the ribs, causing the thoracic
cavity to increase even more in size.
Events of inhalation (cont.)
4. As the size of the thoracic
cavity increases the pressure is
decreased.
5. Atmospheric pressure is now
greater on the outside than
inside the lungs, this creates a
vacuum inside the lungs and
air rushes into the lungs.
6. The lungs become inflated.
Expiration-Exhalation
• Major force being the elastic
recoil of tissue.
• Diaphragm relaxes moving up
decreasing the size of the
thoracic cavity.
• Aided by the internal intercostal
muscles and the abdominal
muscles.
Major Events of Expiration
1. The diaphragm and accessory
muscles relax.
2. The elastic tissues of the lungs,
thoracic cage, and abdominal
organs, which are stretched or
compacted during inspiration,
recoil.
Events of expiration (cont.)
3. Tissues recoiling around the
lungs cause the volume to
decrease, pressure increases
within the lungs.
4. Air is squeezed out of the lungs
into the air passages
Respiratory Air Volumes
• Measured by a device called a
spirometer.
1. Tidal Volume-amount of air moved
into and out of the lungs during a
normal breath. .5 liter
2. Inspiratory Reserve Volume- amount
of air in a forced inspiration. 3 liters
3. Expiratory reserve volume- amount of
air in a forced expiration. 1. liter
4. Residual Volume-air always in the
lungs, keeps the lungs inflated. 1.5
liters
5. Vital Capacity- IRV + TV + ERV= 4.5 L
6.
Total Lung Capacity- VC + RV= 6. L
Non-Respiratory Air Movements
• Cough- closing epiglotis, forcing
air out and releasing it. Clears
the lower respiratory tract.
• Sneeze- caused by upper resp.
tract irritation. Forced expiration
thru the nose.
• Hiccups-spasms of the diaphragm
sound produced by sucking air
over the vocal cords
• Yawning-forced inspiration.
Maybe due to the lack of oxygen.
not entirely understood.
• Laughing or Crying- emotional
response, series of expirations
and inhalations.
Control of Breathing
• Respiratory center of the brain is
located in the medulla
oblongata and pons.
• Controlled by stretch receptors
in lungs and chemoreceptors in
the carotid sinuses and aortic
arch. Sensitive to oxygen levels.
• O2 goes up breathing rate goes
down
• O2 goes down BR goes up
• CO2 goes up BR goes up
• CO2 goes down BR goes down
Breathing Disorders and
Disease
Emphysema- A chronic
degenerative destruction of the
alveoli.
• This decreases the surface area
of the lungs decreasing
diffusion rates of oxygen.
• Major cause is smoking.
Lung Cancer
• Can be epithelial or connective
tissue cancers.
• Cancerous cells crowd out the
functional cells.
• Major cause is smoking
• Exposure to toxins
Asthma
• Allergic reaction to certain
substances causing swelling and
constriction of bronchiole
tubes.
• Decreases or cuts off air
carrying capacity.
• Can be a life threatening
situation.
Tuberculosis
• A chronic bacterial infection
transmitted by the inhalation or
ingestion of infected droplets.
• Lung forms protective masses
of cells called tubercles.
Pneumonia
• Can be viral, bacterial, or
fungal.
• Causes inflammation of lung
tissue
• Decreases efficiency of oxygen
diffusion into the blood.
• Fluid can from tissues can also
accumulate in the lungs.
Common Cold
• Caused by a group of viruses
called rhinoviruses over 200
different types are known.
Cystic Fibrosis
• Autosomal recessive genetic
disorder.
• Mutation of CFTR gene
• Controls sweat, digestive juices,
and mucus production.
• 1 in 25 people of european
descent carry the mutation
• Causes the lungs and pancreas
to secrete great amounts of
mucus.
• Causes frequent lung infections
and an early death
• Most do not live into their 30’s
• No cure
• Lung transplant
Hemothorax-Pneumothorax
Hemothorax-blood in the thoracic
cavity
Pneumothorax- air in the thoracic
cavity
• Caused by punctured lung and
subsequent collapse of lung or
lobe of lung
• Lung loses its residual volume
causing it to collapse
• No diffusion of oxygen will
occur
• Fixed by inserting a chest tube
to reinflate the lung.