Transcript The Respiratory System

The Respiratory System
Chapter 10
• http://www.youtube.com/watch?v=HiT621
PrrO0&feature=related
Introduction
• Main job of respiratory system is to bring
oxygen (O2) into the body and to carry
carbon dioxide (CO2) out of body.
• Body’s cells need a constant supply of
oxygen to burn nutrients to produce
energy.
• How does this take place in a simple,
single celled animal?
• How does this differ from a complex
animal such as a dog or cat?
Two types of Respiration
• External Respiration
• Occurs in the lungs.
• Is the exchange of oxygen and carbon dioxide
between the air that is inhaled into the lungs
and the blood flowing through the pulmonary
capillaries.
• Without which, there would be no oxygen in the
blood to be transmitted to the system.
• Internal Respiration
• Takes place between the body’s cells and the
blood.
• Cells receive oxygen and dispose of their
carbon dioxide
External Respiration
Internal Respiration
The Respiratory System
• Composed of:
• Lungs
• Nostrils
• Nasal passages
• Pharynx
• Larynx
• Trachea
• Bronchi
• Bronchioles
• Alveolar ducts
• Alveoli
Functions of the Respiratory
System
• Primarily:
• Oxygen- carbon dioxide exchange.
• Secondarily:
• Voice production
• Body temperature regulation
• Acid-base balance regulation
• Sense of smell
Voice Production
• Also called phonation.
• Begins in the larynx (voice box).
• Two fibrous connective tissue bands
called the vocal cords (or vocal folds)
stretch across the lumen of the larynx
and vibrate as air passes over them.
• Other structures such as thorax (chest
cavity), nose, mouth, pharynx (throat),
and sinuses may contribute resonance
and other characteristics to the vocal
sounds.
Body Temperature Regulation
• Cold conditions:
• Superficial blood vessels just under the
epithelium of the nasal passages helps warm
inhaled air before it reaches the lungs.
• Keeps chilled air from circulating through the
lungs.
• What could be the problem with this?
• Hot Conditions:
• Aids in cooling through panting.
• Rapid respiration movements caused during
panting cause increased evaporation of fluid
from the lining of the respiratory passages and
mouth, which helps to cool the blood just under
the epithelium.
Acid Base Balance
• Important homeostatic mechanism in the
body.
• pH- unit used to measure relative acidity or
alkalinity.
• Lower the pH, the more acidic the
environment
• Higher the pH, the more alkaline the
environment.
• A pH of 7 is neutral, neither acidic or
alkaline.
• Normal pH of the blood is 7.4
(acceptable range of 7.35-7.45).
Acid-Base Balance Continued…
• Respiratory system contributes to the process of acidbase control by its ability to influence the amount of
CO2 in the blood.
• Higher CO2, lower the blood pH, more acidic the blood.
• Respiratory system can alter CO2 content in the blood
by adjusting how fast air is breathed in and out.
Sense of Smell
• Also called the olfactory
sense.
• Receptors are contained in
patches of sensory
epithelium located up high
in the nasal passages.
Structure of Respiratory System
• Consists of lungs and system of tubes that
connects them with the external
environment.
• Upper Respiratory Tract
• All of the respiratory structures outside
the lungs.
• Lower Respiratory Tract
• All of the respiratory structures within
the lungs.
Upper Respiratory Tract
• Includes:
(all air that enters and leaves lungs does so through
the upper respiratory structures).
• Nose
• Pharynx (throat)
• Larynx (voice box)
• Trachea (wind pipe)
Nose
• Begins with nostrils also known as nares.
• Are external openings of the respiratory
tube that lead into the nasal passages.
Nasal Passages
• Located between the nares and the
pharynx.
• Nasal Septum- a wall that separates the
left nasal passage from the right.
• Hard and Soft palates- separates the nasal
passages from the mouth.
• Contain turbinates (nasal conchae)-thin,
scroll-like bones covered with nasal
epithelium that occupy most of the lumen
of the nasal passages.
Nasal Turbinates
•
Two sets are found in each nasal passage.
• Dorsal Turbinate
• Ventral Turbinate
• These divide each nasal passage into 3 main
passageways, each called a nasal meatus.
• Ventral nasal meatus is located between the
ventral turbinate and the floor of the nasal
passage
• Middle nasal meatus is located between the
two turbinates.
• Dorsal nasal meatus is located between the
dorsal turbinate and the roof of the nasal
passage.
• Common nasal meatus is located on either
side of the nasal septum, is continuous with
other 3 meatuses.
Lining of the nasal passages
• Consists of pseudostratified columnar
epithelium with cilia projecting from the cell
surfaces up into a layer of mucus that is
secreted by many mucous glands and
goblet cells.
• Cilia project from the cell surfaces up into
a layer of mucus
• Extensive complex of large blood vessels
lies just beneath the nasal epithelium.
Functions of the Nasal Passages
• Housing receptors for sense of smell.
• Condition the inhaled air
• Warming
• Warmed by blood flowing in blood vessels
• Humidifying
• By the mucus and other fluids on the
epithelial surface
• Filtering
• Helps to remove particulate matter before it
reaches lungs.
• Due to twists and turns of turbinates.
• Respiratory infections cut down on this
filtering. Why?
Paranasal Sinuses
• Usually just called sinuses
• Outpouchings of the nasal passages that are
contained within spaces in certain skull bones.
• Each sinus is named after the skull bone that
houses it.
• Most animals have two frontal sinuses and
maxillary sinuses.
• Some animals (including humans) have two more.
• Sinuses have same ciliated lining as the nasal
passages. Cilia keep fluid and debris from
accumulating in sinuses and obstructing the
openings of the nasal passages.
Sinusitis
• Inflammation of the sinuses. Due to infection,
tumors, etc.
• Build up of pressure can be very uncomfortable for
the animal.
• Can be treated with medication but if ineffective,
hole may need to be drilled into the sinus to allow
drainage.
Pharynx (Throat)
• Common passageway for both respiratory
and digestive systems.
• Rostral end is divided into:
• Nasopharynx (respiratory passageway)
• Oropharynx (digestive passageway)
• Caudal end is divided into:
• Esophagus (digestive passageway)
• Larynx (respiratory passageway)
Breathing and Swallowing
• Pharynx has to stay open to allow airflow.
• Larynx and pharynx work together to prevent
swallowing from interfering with breathing and vice
versa.
• Swallowing requires:
• stopping the process of breathing,
• covering the opening of the larynx,
• moving material to rear of pharynx,
• open the esophagus,
• move material into it,
• open covering to larynx,
• breathing resumes.
G=Oropharynx
H=Larynx
J=Nasopharynx
K=Esophagus
I=Trachea
Larynx
• Commonly called the “voice box” .
• Short, irregular tube that connects the
pharynx with the trachea.
• Made of segments of cartilage that are
connected to each other and the
surrounding tissues by muscles.
• Supported in place by the hyoid bone.
Cartilage components of the
Larynx
•
•
•
•
Epiglottis
• single, leaf-shaped; projects forward from the ventral
portion of the larynx
• During swallowing, the epiglottis is pulled back to
cover the opening of the larynx
Arytenoid cartilages
• paired; attachment site of the vocal cords
• Muscles adjust the tension of the vocal cords by
moving the cartilages.
• Arytenoid cartilages and the vocal cords form the
boundaries of the glottis-the opening into the larynx.
Thyroid cartilages
• Shaped as a V that forms and supports the ventral
portion of the larynx.
Cricoid cartilage
• Ring-shaped, helps from and support the caudal
portion of the larynx.
Larynx continued
• Vestibular folds (false vocal cords) - are
found in nonruminant animals. Are a
second set of connective tissue bands.
• Not involved in voice production.
• Each side of larynx, blind pouches called
lateral ventricles project laterally into the
space between the vocal cords and the
vestibular folds.
• These lateral ventricles are often
involved in the treatment of a condition
in horses called roaring (laryngeal
hemiplegia).
Laryngeal Hemiplegia (Roaring)
or Laryngeal paralysis
• Occurs when muscles that tighten
cartilage are paralyzed.
• At rest usually does not cause a problem
• When animal exercises , may result in
obstruction of the glottis.
• Surgery may remove ventricle to allow
scar tissue to tighten cartilage.
Laryngeal Intubation
• Process in which an endotracheal
tube is placed through the glottis to
the trachea.
• May be helped by the use of a
laryngoscope- an instrument that
helps to hold down epiglottis.
• Laryngospasms –sometimes seen
in cats, when glottis is touched,
larynx slams shut. Is reflex.
Aspiration Pneumonia
• Inflammation of the lungs produced by inhalation
of a foreign material.
• Use caution when administering liquids to animals
(remember the swallowing process).
• May see during anesthesia.
• May potentially be fatal.
Laryngeal Functions
• 1. Voice Production
• Originates at vocal cords in the larynx.
• Vocal cords are attached to arytenoid cartilages
and stretch across the lumen of the larynx.
• As air passes over vocal cords, they vibrate and
produce sounds.
• Muscles attached to arytenoid cartilages control
the tension of the vocal cords.
• Lessening tension of the vocal cords allows for
lower pitched sounds.
• Tightening of the vocal cords allows for higher
pitched sounds.
Laryngeal Functions
• 2. Prevention of Foreign material being
inhaled.
• Accomplished by trapdoor action of the
epiglottis.
• The moving up and down of the adam’s
apple is part of this process.
• 3. Control of airflow to and from lungs.
• Partially through epiglottis action when
swallowing occurs but also through
adjustments in the size of the glottis.
• Adjustments in the size of the glottis.
• May even be helpful in straining.
Coughing
• Cough is generated behind a closed
glottis.
• Breathing muscles contract, compressing
the thorax.
• Builds pressure behind the closed glottis.
• When glottis suddenly opens, the forceful
release of air results in a cough.
• Purpose of coughing is to clear mucus and
other matter from lower respiratory
passages.
Trachea
• Windpipe- short, wide
tube that extends from
the larynx down through
the neck region into the
thorax.
• Lined with ciliated
epithelium.
• Bifurcation of the
Trachea- occurs at
about the level of the
heart.
Trachea
• Structurally, trachea is a tube of fibrous
tissue and smooth muscle held open by
hyaline cartilage rings and lined by the
same ciliated epithelium that is present in
the nasal passages.
• Hyaline cartilage rings are C shaped.
Trachea continued
• Ciliated lining of the trachea is similar to
the nasal passages.
• The mucous layer on its surface traps tiny
particles of debris that have made it down
this far into the respiratory tube.
• Eventually reaches pharynx and is
swallowed.
Collapsing Trachea
• Pushing down of the cartilage
area, obstructs air flow.
• Causes dry, honking cough.
Lower Respiratory Tract
• Consists of:
• Bronchi
• Bronchioles
• Alveolar ducts
• Alveoli
Bronchial Tree
• Air passageways that lead from the
bronchi to the alveoli.
• Divide into smaller and smaller
passageways.
• After enters the lung, each main bronchus
divide into smaller bronchi, which divide
into smaller bronchi, eventually getting to
bronchioles.
• Bronchioles continue to subdivide down
to alveolar ducts.
• Alveolar ducts end in alveolar sacs.
Bronchial Tree continued
• Bronchial tree are not just rigid tubes.
• Diameter of each can be adjusted by smooth
muscle fibers in the wall.
• What kind of smooth muscle is this?
• Autonomic Nervous system controls this smooth
muscle.
• During times of intense physical activity, bronchial
smooth muscle relaxes, allowing air passageways
to dilate to their maximum. Called Bronchodilation
• During relaxed time, smooth muscle partially
contracts, reducing size of air passageway. Called
Bronchoconstriction.
Asthma
• Bronchioles are sometimes overly
sensitive to certain irritants
• Results in bronchoconstriction
• Can range from mild and annoying
to life-threatening
• More common in humans
• Occurs most commonly in cats in the
summer
Alveoli
• Where external respiration takes place.
• Where oxygen and carbon dioxide are
exchanged.
• All respiratory structures exist to move air
in and out of alveoli.
• Tiny, thin walled sacs surrounded by
capillaries.
• Walls are composed of simple squamous
epithelium.
• These thin layers allow for easy movement
of oxygen and carbon dioxide.
Alveoli Continued
• Each alveolus is lined with surfactant – a
fluid that helps reduce surface tension of
the fluid.
• This prevents the alveoli from collapsing
as air moves in and out during breathing.
Lungs
•
•
•
•
Two lungs form a shape like a cone.
Base of lungs are on the diaphragm.
Apex of the lung is near the top (pointed like area).
Mediastinum- area between the two lungs, also called
what??
Lobes of the Lungs
• Left Lung
• Cranial lobe
• Caudal lobe
• Right Lung
• Cranial lobe
• Middle lobe
• Caudal lobe
• Accessory lobe
Horse lung is different… How?
Lungs continued
• Hilus- where air, blood, lymph, and nerves
enter and leave the lung.
• Only area of lung that is fastened in
place.
1. Oblique fissure
2. Vertebral part
3. Hilum of lung
4. Cardiac impression
5. Diaphragmatic surface
Lungs Continued
Circulation through the lungs
• Blood supply to and from the lungs is
called pulmonary circulation
• Blood enters via pulmonary artery
• Blood reenters heart via pulmonary vein
Consistency of Lungs
• Light and have a spongy consistency
• Fetal lungs have a solid consistency.
Why??
• Testing used to determine if a breath was
taken.
Thorax
• Also known as the thoracic cavity – chest cavity.
• Bound by thoracic vertebrae dorsally, ribs and
intercostal muscles laterally, and the sternum
ventrally.
• Contains:
• Lungs
• Heart
• Large blood vessels
• Nerves
• Trachea
• Esophagus
• Lymphatic vessels
• Lymph nodes
Thorax Continued
• Pleura- thin membrane that covers the organs and structures in the
thorax and lines the inside of the thoracic cavity.
• Visceral layer of pleura- covers the thoracic organs and structures.
• Parietal layer of pleura- lines the cavity
• Between pleural layers is a lubricating fluid.
Diaphragm
• Dome shaped.
• Thin sheet of skeletal muscle
that forms caudal boundary of
the thorax.
• When diaphragm contracts,
dome flattens out and enlarges
thorax.
• Helps with inspiration
Respiration
• Process requires effective movement of air
into and out of lungs at an appropriate rate
and in sufficient volume to meet the body’s
needs at any particular time.
• Pressure within the thorax is negative with
respect to atmospheric pressure.
• Pulls lungs tight against the thoracic
wall
• Flexible nature of lungs allows them to
conform with shape of the thoracic wall.
• Pleural fluid provides lubrication.
• Lungs follow thoracic wall.
Respiration continued
• Negative pressure also aids in the return
of blood to the heart.
• Helps to pull blood into the large veins of
the mediastinum.
• Helps to draw blood from the midsize
veins and then dump these into the atria.
Pneumothorax
• Loss of air into thorax.
• Disrupts the negative pressure.
• Causes can be due to trauma or lung
disease.
Inspiration
• Process of drawing air into the lungs.
• Also called inhalation
• Basic process is enlargement of the
volume of the thoracic cavity by the
inspiratory muscles.
• Main inspiratory muscles:
• Diaphragm
• External Intercostal muscles.
• Located in the external portion of
the spaces between the ribs
(intercostal spaces).
Expiration
• Process of pushing air out of the
lungs.
• Also called exhalation.
• Thoracic cavity is decreased in size,
compresses lungs and pushes air out
through the respiratory passages.
• Main muscles are the internal
intercostal muscles and the abdominal
muscles.
• How do muscles work??
• Does not require as much work as
inspiration
Respiratory Volumes
• Tidal volume – volume of air inspired and expired
during one breath.
• Varies according to body’s needs.
• Smaller when animal is at rest and larger when
excited and active.
• Minute volume – volume of air inspired and expired
during one minute.
• Calculated by multiplying the tidal volume by
breaths per minute.
• Measured in mL or Liters
• Residual volume – volume of air remaining in the
lungs after maximum expiration.
• Residual volume always remains.
• Lungs will never be completely emptied of air.
Lung volumes continued
• Measured with a spirometer.
Exchange of Gases in Alveoli
• Simple diffusion process from areas of
high concentration to areas of low
concentration.
• Atmospheric air contains 21 % oxygen and
0.03 % carbon dioxide.
• Blood in lungs is high in carbon dioxide
and low in oxygen.
• Oxygen diffuses from alveolar air to blood,
carbon dioxide diffuses to alveolus which
is refreshed with oxygen from next breath.
Partial Pressure of Gases
• Dalton’s law- states that the total pressure of a
mixture of gases is the sum of the pressure of
each individual gas.
• Partial pressure- the pressure of each individual
gas.
• Partial pressure is expressed with a P before
chemical symbol for gas.
• Partial pressures of O2 and CO2 in the blood of
alveolar capillaries is determined by the partial
pressures of O2 and CO2 in alveolar air
• the greater the amount of a gas in the air you
breath, the more concentrated it will be in the
blood.
Control of Breathing
• Breathing does not require conscious effort
although use skeletal muscles that are under
voluntary control.
• Is controlled by an area in the medulla oblongata of
the brain stem.
• Known as the respiratory center.
• Houses control systems for inspiration,
expiration, and breath holding.
• Subconsciously sends nerve impulses to the
muscles to direct them how to contract.
• Usually can only control breathing
consciously for a short period of time before
autonomic system kicks back in.
Two systems to control breathing
• 1. Mechanical system
• Sets routine inspiration and expiration
limits.
• 2. Chemical system
• Monitors that the levels of certain
substances in the blood and directs
adjustments in breathing if they get out
of balance.
Mechanical Control
• Operates through stretch receptors in the
lungs that set limits on routine expiration
and inspiration.
• When lungs inflate to a certain point, nerve
impulse says that lungs are full and stops
muscle contractions that allow lungs to fill.
• Then will notify muscles to contract to
start expiration
Chemical Control
• Monitors blood and affects breathing if something
gets out of balance.
• Monitors:
• CO2 content
• The pH
• O2 content
• Blood level of CO2 and blood pH are linked. As
CO2 rises, pH goes down. If this occurs,
chemical control system signals to increase rate
and depth of breathing to even it out.
• Vice versa if pH goes up.
Chemoreceptors
• Peripheral- aortic bodies and carotid
bodies
• Central- found in the medulla of the brain.
• Normal respiratory rates:
• 10-30 breaths per minute in dog
• 20-30 breaths per minute in cat.
Bagging a Patient
• Term used to describe manual control of an
anesthetized patient’s breathing by squeezing and
releasing the rebreathing bag.
• May cause more CO2 than normal to be removed
from lungs, so may trigger that patient will not
breathe once bagging stops.
• Hypoxia- Decrease in blood O2.
• If this occurs, chemical control system signals
the respiratory center to increase rate and
depth of breathing so more O2 will be taken in.
Terms
• Sneeze- similar to a cough, but originates in the
nasal passages, burst of air is directed through the
nose and mouth in effort to eliminate the irritant.
• Yawn- slow, deep breath taken through a wideopen mouth. May be stimulated by slight decrease
in oxygen levels, drowsiness, fatigue, and
boredom.
• Sigh- slightly deeper than normal breath. May
serve to expand lungs more than normal. May hear
“sighing” patient under anesthesia.
• Hiccups- spasmodic contractions of the diaphragm
accompanied by sudden closure of the glottis.
Usually self-limiting
• http://www.youtube.com/watch?v=sU_8ju
D3YzQ&NR=1&feature=fvwp
• http://www.med.ucla.edu/wilkes/lungintro.h
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