Respiratory System

Respiratory System

By Aleks Chernyy, Ryan Blount, Laura Tassone, Wassim

Respiratory System

1. Conducting

2. Respiratory

Conducting Portion

1. Nasal cavities2. Pharynx3. Larynx4. Trachea 5. Bronchi

Conducting-Respiratory Junction

Respiratory Bronchioles is the Conducting- Respiratory Junction.

a. Alveoli out-pocketings

b. Clara cells begin to predominate

Histology of the trachea

Cartilage

Ciliated epithelium

Trachea

C-Shaped Cartilage What is its function? maintains patency, especially during forced expiration

Within the Trachea we find?a. Pseudostratified ciliated columnar epitheliumb. Goblet cellsc. Basal cellsd. Brush cells

What types of Glands are present in RS?What do they excrete?

Mucous - MucinSerous - Glycoproteins, polysacharides & bacteriosidic proteins

Trachea

Basal Bodies are associated with cilia and are highly eosinophilic

Mucous gland vs. serous gland

Mucus Glands vs Serous Glands

Respiratory Portion Structures:1. Respiratory

bronchioles 2. Alveolar ducts3. Alveoli

The Respiratory Segment

• Respiratory Bronchioles – Give off Alveoli– Give off alveolar ducts

• Alveolar ducts– Give off Alveoli only

• Alveolar sacs– Spaces surrounded byclusters of alveoli

Upper Respiratory

The larynx first appears as an outgrowth from the foregut.

The outgrowth of tissue is called the respiratory diverticulum or the lung bud.

The formation of the lung bud occurs when two lateral folds of splanchnic mesoderm and endoderm meet in the midline and separate the larynx and trachea from the esophagus.

The lung bud is a ventral diverticulum of endoderm that arises from the floor of the foregut caudal to the pharynx. The diverticulum forms a groove in the floor of the pharynx called the laryngotracheal groove.

The Lower Respiratory System

Develops during week 4 (26-27 days)

Starts as a median laryngotracheal groove in the caudoventral wall of the primitive pharynx.

The endoderm lining the groove gives rise to the epithelium and glands of the larynx, trachea, bronchi and the pulmonary epithelium.

Connective tissue, cartilage and smooth muscle of these structures develop from the splanchnic mesenchyme surrounding the foregut.

DevelopmentThe laryngotracheal groove deepens into a diverticulum ventrally which enlarges distally into a lung bud.

The diverticulum becomes separated from the primitive pharynx by longitudinal trachoesophageal folds

The folds fuse to form the trachoesophageal septum, dividing the foregut into the ventral laryngotracheal tube and the dorsal esophagus.

Fistula

A fistula may exist connecting trachea and esophagus and resulting in abnormal communication between the two.

This is usually associated with superior esophageal atresia. In a newborn infant, this is associated with coughing and choking upon swallowing.

Gastric contents may reflux into the trachea and lungs resulting in pneumonia or pneumonitis (inflammation of the lungs).

An excess of amniotic fluid (polyhydramnios) is associated with esophageal atresia and trachoesophageal fistula because amniotic fluid may not pass to the stomach and intestines for absorption and transfer via the placenta for disposal

STAGES OF THE DEVELOPMENT OF LUNGS

Pseudoglandular 5 – 16 weeks Branching has Period continued to form terminal bronchioles

Canalucular Period 16 – 26 weeks Each terminal

bronchiole divides into

2 or more respiratory bronchioles which in turn divide into 3-6 alveolar ducts

Terminal Sac 26 weeks to birth Terminal sacs, Primitive alveoli form and capillaries establish close contact

Alveolar Period 8 month – childhood Mature alveoli have well-developed epithelial endothelial contacts.

Histology

What is the basic name for the Cells within the Respiratory System?

Pneumocytes1. Type I 2. Type II3. Clara Cell4. Goblet Cells5. Cartilage6. Alveolar Macrophages

Type I Alveolar Epithelial Cell

Features:cuboidal, lined bronchioles change into thin, flat cells

Functions?1. gas exchange between blood 2. air possible in primitive alveoli

Clinical Correlations

Type II Alveolar Epithelial Cell

Features:cuboidal, granular, alveolar septal junctions

Function:1. Produces surfactant (Lower Surface Tension

Normally produced at end of 6th month maximum production 2 weeks before birth

Clinical Correlation.Hyaline Membrane Disease (RDS)

Flattened squamous cells

Line the alveolar surfaces and are extremely attenuated.

Make up 97% of the alveolar surface.

Have occluding junctions and desmosomes

They are roughly cuboidal in shape.

Found interspresed among the type I alveolar cells with

which they have occluding and desmosomal juntions.

Make up 3% of the alveolar surface.

Contains lamellar bodies that stores pulmonary

surfactants

TYPE I vs TYPE II

Hyaline Membrane Disease (RDS)SYMPTOMS:1. Respiratory difficulty at birth that gets progressively worse2. Cyanosis 3. Flaring of the nostrils4. Tachypnea (Rapid Breathing)5. Grunting sounds with breathing6. Chest retractions (pulling in at the ribs and sternum during

breathing)

What is the problem?7. Not enough Surfactant. ( produced in the fetus 24 to 28 weeks)

8. Surfactant lowers surface tension in the airways keeping

alveoli open.9. Without Surfactant, the alveoli collapse. 10. Damaged cells collect in the airways and affect breathing

ability. 11. These cells are called hyaline membranes. The baby works

harder at breathing, trying to re-inflate the collapsed airways.12. As the baby's lung function decreases, carbon dioxide builds up

in the blood. This can lead to increased acid in the blood called acidosis, a condition that can affect other body organs.

RDS Treatment1. Placing an endotracheal (ET) tube into the

baby's windpipe2. Mechanical breathing machine3. Supplemental oxygen 4. Continuous positive airway pressure (CPAP) 5. Surfactant replacement with artificial

surfactant - most effective if started in the first six hours of birth.

6. Surfactant is given as prophylactic (Preventive) treatment for some babies at very high risk for RDS. Surfactant is usually given in several doses.

7. Medications (Pain)

Clara Cell1.Secrete CCSP2.Protect Bronchiolar epitheliem3.Detoxify harmful substances4.Act as stem cells and multiple5.Unique to Bronchioles

Historical ControversyMax Clara, product of unethical research.

The Clara Cell Controversy

What are Goblet cells?

What is their function?

Clinical Correlation?Chronic Pulmonary Emphysema

MD 3 QUIZ

Answers

Hyaline Cartilage

The LarynxCartilageWith the exception of the epiglottis, all larynx cartilage is hyaline cartilage.

The Adam's apple is really the laryngeal prominence, where the curved disc shaped thyroid cartilage bond.

Trachea Cartilage

The trachea is made up of between 16 and 20 “C” shaped rings

The trachea is flexible and twistable,

Without cartilage rings, it would collapse under the partial vacuum formed when inhaling.

The Bronchi

• The first few levels of bronchi are supported by rings of cartilage.

• Branches after that are supported by irregularly shaped discs of cartilage, while the latest levels of the tree have no support whatsoever.

Facts about alveolar macrophages?• An alveolar macrophage (or dust cell) is a type

of macrophage found in the pulmonary alveolus, near the pneumocytes, but separated from the wall.

• Alveolar macrophages are one of the many types of white blood cells(leukocytes) present in body tissues. They are important in immune response and cell stability because they mobilize in cell tissue to attack large foreign particles such as bacteria, yeast, and dead cells.

Where do alveolar macrophages derive from?

• Macrophages are derived from precursor cells called monocytes that first develop in bone marrow.

• Macrophages are any of the large, mononuclear, highly phagocytic cells derived from monocytes that occur in the walls of blood vessels (adventitial cells) and in loose connective tissue (histiocytes, phagocytic reticular cells).

Alveolar macrophage function

• Alveolar macrophages enter the blood and travel throughout the body in the circulatory system. When needed circulatory monocytes move into tissue where they become macrophages. Here a lung (alveolar )macrophage is seeking foreign bacteria (Escherichia coli) with specialized cell extensions called filopodia.

• Macrophages engulf and digest foreign materials in a process known as phagocytosis.

• Alveolar macrophages are frequently seen to contain granules of exogenous material such as particulate carbon that they have picked up from respiratory surfaces. Such black granules may be especially common in smoker's lungs or long-term city dwellers

• Inhaled air may contain particles or organisms which would be pathogenic. The respiratory pathway is a prime site for exposure to pathogens and toxic substances.

• The respiratory tree, comprising the larynx, trachea, and bronchioles, is lined by ciliated epithelia cells that are continually exposed to harmful matter [1

• When these offensive agents infiltrate the superficial barriers, the body's immune system responds in an orchestrated defense involving a litany of specialized cells which target the threat, neutralize it, and clean up the remnants of the battle.

Respiratory Histology

Epithelium of the Respiratory System

Upper 1/3 of trachea has squamous cells

Mid 1/3 of trachea is a combination

Main respiratory epithelium is tall columnar ciliated epithelium

The more you smoke, the longer the zoneof squamous cells.

Conducting EpitheliumWhat is the predominant type of epithelium that is found in the conducting portion of the respiratory system?

Pseudostratified columnar epithelium `````````````````````````````````````````````````````````````` Clinical Correlation?Metaplasia Metaplasia

Metaplasia

QUIZ

A 65-year-old man with an 80-pack-year history of smoking presents with a cough and increasing dyspnea over the past 6 weeks. A 2-cm diameter mass is seen in the left lower lobe on x-ray of the chest. A sample of nonneoplastic tissue from the lung biopsy is shown in the image. Which of the following types of epithelium not normally present in the lung lines the bronchus shown in this image?

(A) Pseudostratified columnar(B) Simple squamous(C) Stratified columnar(D) Stratified squamous(E) Transitional

AsthmaWhat is Asthma? Inflammatory process of the airways characterized by reversible bronchospasm, and increased airway secretions.

Clinical picture: Shortness of breath, wheezing andchronic cough.

Treatment:1. Steroids2. Exercise Asthma/Albuterol3. Beta 2 agonists (Short Acting)4. Anticholinergic inhalers

CiliaWhy do we have cilia in the conducting portion of the RS?a. Line the entire airwayb. Beat in one direction c. Has the 9 + 2 configuration d. 9 microtubules surrounding 2 actin proteinse. Need a Dynein arm to have flexibility

Clinical Correlation:Kartagener Syndrome

Kartagener SyndromeSymptoms:1. Chronic sinus infection 2. Frequent lung infections, such as pneumonia and bronchitis 3. Bronchiectasis - lung damage from frequent infections 4. Frequent ear infections

Whats the Problem?Dynein arm is defective

Results in ?a. Obstructive lung diseaseb. Bronchiectasisc. Infertilityd. Situs Inversus

Treatment?

Lymphoid Tissue

BALT (bronchus-associated lymphoid tissue)

Similarity to Peyer’s PatchesHigh percentage of IgALymph Drainage

Important Respiratory Functions

1. Hypoxia causes ______________everywhere in the body except the ______________, where it causes vasoconstriction.

2. CO2 is transported in the blood mainly in the form of _________ and to a lesser extent bound to___________.

3. Hering Bruer reflex: Inhibition of _____________due to stretch of lung tissue.

4. Central: In medulla, and is stimulated by high CO2 and high H.

5. Peripheral: In carotid and aortic bodies. Stimulated by low oxygen, high CO2 and high H. So when they ask you in the USMLE about how breathing is stimulated in a patient with low oxygen but normal CO2, the answer is obviously peripheral receptors.

CaseIn August 1963, First Lady Jacqueline Bouvier Kennedy was hospitalized in her 34th week of pregnancy at the Otis Air Force Base Hospital. Her fetus was in distress, but labor did not progress. On August 7, she underwent a cesarean section to deliver Patrick Bouvier Kennedy, who weighed 4 pounds, 10.5 ounces (2,112 grams). After delivery, the baby developed difficulty breathing,

The Physician ordered oxygen therapy, what was his diagnosis?

What prenatal test, if available at the time would serve to predict the Child’s condition?

What other steps would you take to improve the child probability of survival.