The Respiratory System

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The Respiratory System
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Respiration begins in the nose
Psuedostratified Columnar Ciliated epithelial
tissue lines the nose to warm and mositen the
inhaled air. Mucous cells are found within the
lining to allow moistening of the air.
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3 Areas of the Oral Cavity

• OROPHARYNX
• -soft palate to epiglottis
• -two sets of TONSILS
• a. Palatine
• b. Lingual
• -the tonsils remove pathogens that enter
  the pharynx. They contain lymphocytes

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• 2. NASOPHARYNX
• -located superior and posterior to the
  soft palate.
• -contains the PHARYNGEAL TONSILS and
  TUBAL TONSILS

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The soft palate is a muscular structure that
separates the nasal cavity from the oral
cavity. The soft palate moves superiorly to seal
the nasal cavity during swallowing.
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An 11-month-old girl's mother noted this
asymptomatic cyst on her daughters soft palate.
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• 3. LARYNGOPHARYNX
• -inferior to the epiglottis and
  posterior to the larynx.
• - this division opens into the esophagus
  and larynx.

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The Lower Respiratory Tract

• The TRACHEA begins at the level of C6 superiorly.
• Directly superior to the beginning of the trachea
  is the LARYNX (vocal cords).
• The trachea bifurcates into the BRONCHI at the
  sternal angle (T4 or T5) when supine (laying on
  the back) or T7 when standing.

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• The trachea is composed of 16-20 cartilagenous
  rings (hyaline cartilage).
• These rings are flexible but keep the trachea
  open.
• Each ring is open in the back (allows flexibility)

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• The rings are approximately 1.5 inches in
  diameter and held together by connective tissue.
• The connective tissue is dense CT.
• Air can pass through the tube without resistance.

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• The trachea must be able to filter debris (dust
  or dirt). Coughing occurs when such debris
  enters the trachea.

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Principles of Animal Physiology
Respiratory System
Air Respirers

• Mammalian respiratory pathway

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Nasal cavity and trachea.

• Psuedostratified columnar ciliated epithelium.
• Mucous cells (goblet cells)
• Sub-mucosal tubuloacinar seromucous gland
• Intraepithelial gland in chicken.

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Principles of Animal Physiology
Respiratory System
Air Respirers

• Ciliated respiratory epithelium cells

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Histology of the trachea
Ciliated epithelium
cartilage
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Principles of Animal Physiology
Respiratory System
Air Respirers

• Diagram representing the human airways

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Principles of Animal Physiology
Respiratory System
Air Respirers

• Respiratory zone structures

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Bronchi

• Psuedostratified columnar to columnar to cuboidal
  epithelium with mucous cells and mixed bronchial
  glands in all species except goat.

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Bronchioles

• Simple columnar to cuboidal epithelium
• Ciliated cells
• Bronchiolar exocrine glands.
• Both secretory and metabolizing xenobiotic
  compounds.
• Adundant in horses and sheep.
• Min in carnivores, cattle and pigs.

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Principles of Animal Physiology
Respiratory System
Air Respirers

• Alveolus and associated pulmonary capillaries
• Alveolar epithelial cells
• Type I flattened processes which cover most of
  the inner surface
• Type II produce and store surfactant
• Macropharges phagocytic cells
• pores of Kohn - permit airflow between adjacent
  alveoli, a process known as collateral ventilation

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The Larynx

• The LARYNX (voice box) is a modified portion of
  the trachea.
• It is superior to the trachea.
• There are cartilaginous rings that are connected
  by dense connective tissue forming a tube.

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• The TYROID CARTILAGE is shaped like a shield when
  viewed from the anterior surface. This is the
  ADAMS APPLE. This is not a complete ring.
• On the posterior side of the thyroid cartilage,
  the CRICOID CARTILAGE extends superiorly to where
  the thyroid cartilage would be. This cartilage
  is sometimes called the SIGNET RING CARTILAGE.

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• It has a narrow band across the anterior side.
• It is superficial to the thyroid cartilage
  posteriorly where it is connected by the
  CRICOTHYROID LIGAMENT (dense connective tissue).
• Inferiorly, the cricoid is attached to the first
  ring to the trachea by dense CT.

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• The EPIGLOTTIS is a spade shade cartilage that is
  important during swallowing.
• It tips inferiorly to seal off the glottis and
  prevents food from entering the trachea.
• The ARYTENOID CARTILAGE is below the epiglottis
  at the entrance to the GLOTTIS.
• The GLOTTIS is a passageway into the trachea.
  The thyroid cartilage forms the walls of the
  glottis. The arytenoid cartilage extends
  inferiorly into the glottis.

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• The arytenoid cartilages anchor the vocal cords.
• The true vocal cords are located inferiorly
  inside the glottis.
• As air passes over the vocal cords they flutter,
  producing sound from the vibration.
• Pitch can be changed by tightening or loosening
  the cords.
• In humans, the tongue is used to make sense of
  the sounds (make words). You cannot talk if your
  tongue is not functioning.
• There are folds covering part of the epiglottis
  called FALSE VOCAL CORDS.

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Epiglottis
Hyoid Bone
Thyrohyoid Ligament
Thyroid Cartilage
Aryetnoid cartilage
Cricoid cartilage
trachea
ANTERIOR
Tracheal rings
POSTERIOR
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Tracheostomy Step 1
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Step 2
The skin incision is made with a Colorado Needle
mounted on an electric knife (Bovie).  A steel
blade scalpel is as good and is preferred by many
surgeons.
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Step 3
After incising the subcutaneous tissue and
platysma, the strap muscles are separated in the
midline. The strap muscles is a name given to
the four infrahyoid muscles that lie in front of
the larynx. They are the sternohyoid,
sternothyroid, thyrohyoid and the omohyoid.
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Step 4
The isthmus of the thyroid gland is either
retracted or divided in the midline. (In this
picture, the isthmus has been divided and
retracted laterally, along with the strap
muscles.)  The anterior tracheal wall is divided
between the third and fourth tracheal rings.  A
clamp is used to widen the tracheal opening.  The
endotracheal tube is seen inside the tracheal
lumen
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Normal vocal cords as they appear through a 90
degree telescope. The cords are partially opened
and the opening into the trachea can be seen
between them.
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One may compare this person at a high and a low
pitch, demonstrating the elongation of the vocal
cords that takes place to raise pitch by
contracting the Cricothyroid muscles
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Acute Laryngitis
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Chronic Laryngitis
68 year old non-smoker with history of
gastroesophageal reflux. She complained of daily
belching and burning in her throat due to the
stomach acids.
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Wider, shorter, and more vertical than the left
trachea
Right Primary Bronchus
Left primary bronchus
Both primary bronchi have the same anatomic
structure as the trachea.
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• The primary bronchi divide to form SECONDARY
  BRONCHI (lobar bronchi).
• There is one secondary bronchus for each lobe of
  the lungs.
• There are 2 lobes on the left lung.
• There are 3 lobes on the right lung.
• These also have the same anatomy as the trachea.

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• The secondary bronchi branch to form TERTIARY
  BRONCHI.
• They continue to branch.
• As they get smaller, they lose their cartilage.
• When they lose their cartilage, they are called
  BRONCHIOLES which are microscopic.

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Histology of the Bronchus
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• The bronchioles terminate in the ALVEOLI through
  an ALVEOLAR DUCT.
• The walls of the alveoli are one-cell thick and
  is covered in capillaries.
• The alveoli are the functional unit of the lungs.

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Bronchiole and Alveolar Duct
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• There are air sacs, where gas exchange occurs.
• Walls of the alveoli are highly vascularized.
• The alveoli are the terminal branches of the
  BRONCHIAL TREE. This arrangement allows for a
  drastic increase in surface area.

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The Lungs

• The right lung starts 1 above rib 1 and crosses
  the clavicle at about the medial 1/3 of it. It
  progresses inferiorly to costal cartilage 6
  (midsternally). At the midaxillary region, it is
  at rib 8 and rib 10 at the vertebral border.

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• The right lung has 3 lobes (4 in the cat).
• The left lung starts about 1 above rib 1 and
  crosses deep to the manubrioclavicular joint.
  There it goes to the left and continues
  inferiorly to rib 6.
• The left lung has an indentation called the
  CARDIAC NOTCH. This area provides room for the
  HEART.

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• Lung size varies from individual to individual.
• The left lung has 2 lobes (3 in the cat).
• The lobes are anatomically and functionally
  separate. Thus, they are independent of each
  other.

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• There is a deep fissure between the lobes. The
  lobes overlap each other like shingles.
• The OBLIQUE FISSURE on each lobe begins
  posteriorly across from the root of the spine of
  the scapula at T3. They come around laterally
  and inferiorly in an oblique path and eventually
  reach rib 6 on both sides.

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• On the right side, there is also a TRANSVERSE
  FISSURE which follows rib 4 anteriorly. It joins
  the oblique fissure midaxillary.
• On the posterior surface, one can see only 2
  lobes on each lung. On the anterior surface, you
  can see the third lobe on the right lung.

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• The lobes are further divided into LOBULES.
  These cannot be separated as easily as the lobes
  can.
• They are functionally separate.
• They are also anatomically partitioned to allow
  removal of a lobule while keeping the
  functionality of the rest of the lung.

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The Pleural Cavity
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Slide of Alveoli
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• Gaseous exchange relies on simple diffusion. In
  order to provide sufficient oxygen and to get rid
  of sufficient carbon dioxide there must be
• a large surface area for gaseous exchange
• a very short diffusion path between alveolar air
  and blood
• concentration gradients for oxygen and carbon
  dioxide between alveolar air and blood.

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Intercostal Muscles

• External Intercostals
• O Inferior border of rib above I Superior
  border of rib below
• Fibers run OBLIQUE (down and forward)
• Aid in Inspiration (lift ribcage, increase
  dimensions)
• Internal Intercostals
• O Superior border of rib above I Inferior
  border of rib below
• Fibers run at RIGHT ANGLES to external
  intercostals
• Aid in expiration (depress ribcage, decrease
  dimensions)
• Innermost Intercostals
• Attachments similar to Internal Intercostals,
  Attach ribs
• Fibers run Anterior/Posterior

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Neurovascular Bundle of Intercostals

• VAN (vein, artery, nerve)
• Intercostal vein
• Intercostal artery
• Intercostal nerve
• Sit in Subcostal Groove
• Between Internal Intercostal and Innermost
  intercostal muscles

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During inspiration the diaphragm moves downward
allowing air to enter the respiratory tract. The
external intercostals contract along with the
pectoral muscles. During Expiration, the
diaphragm moves upward forcing air out the lungs.
The internal intercostals contract.