Respiratory System Quiz: Bronchi and Alveoli

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Questions and Answers

What is the primary function of Type I pneumocytes in the alveoli?

Produce surfactant to reduce surface tension

Support the structural integrity of the alveolar wall

Facilitate gas exchange by forming a blood-air barrier (correct)

Act as macrophages to remove pathogens

Which of the following structures are included in the acinus of the lung?

Pleura, lobule, fissures

Bronchus, bronchiole, alveoli

Alveolar sac, interstitial fibroblasts, types I and II cells

Terminal bronchiole, respiratory bronchiole, alveolar duct (correct)

What is the function of Type II pneumocytes in the alveoli?

They facilitate blood flow in the alveolar capillaries

They serve as immune cells

They form a barrier for gas exchange

They produce surfactant (correct)

How is the gas exchange barrier structured in the alveolus?

Type I cells, fused basal laminae, and capillary endothelial cells Signup and view all the answers

What is the role of fibroblasts in the interstitial space of the alveoli?

Provide structural support and produce extracellular matrix components Signup and view all the answers

What describes empysema in relation to lung anatomy?

It involves destruction and enlargement of the airspaces in the lungs Signup and view all the answers

What is the primary function of alveolar ducts?

Connect the respiratory bronchioles to alveolar sacs Signup and view all the answers

What anatomical feature helps maintain the structure of alveoli during ventilation?

Pores of Kohn allowing airflow between alveoli Signup and view all the answers

What is the primary function of surfactant in the alveoli?

To prevent the collapse of alveoli during expiration Signup and view all the answers

Which cells are responsible for producing surfactant in the alveoli?

Type II pneumocytes Signup and view all the answers

What is the consequence of having low or no surfactant in the alveoli as described by LaPlace's law?

Higher pressure is required to keep alveoli open Signup and view all the answers

What is the role of pulmonary alveolar macrophages?

To remove debris and particles from the alveoli Signup and view all the answers

Which type of blood vessels provides a low-pressure blood supply to the alveoli?

Pulmonary arteries Signup and view all the answers

Which layer of pleura covers the lungs?

Visceral pleura Signup and view all the answers

What composes the pleural cavity?

Serous fluid Signup and view all the answers

What does interstitial fibrosis in conditions like ARDS indicate?

Thickening of hyaline membranes Signup and view all the answers

Which structure functions to line the thoracic cavity?

Parietal pleura Signup and view all the answers

What is the function of bronchiolar lymphatics?

Follow bronchovascular structures and drain lymph Signup and view all the answers

What is the primary function of Clara cells found in terminal bronchioles?

To make surfactant components Signup and view all the answers

What structural change occurs as the bronchi undergo branching?

Disappearance of cartilage Signup and view all the answers

Which component is NOT present in bronchioles?

Glands Signup and view all the answers

As bronchioles narrow, what type of epithelium is primarily found?

Simple cuboidal epithelium Signup and view all the answers

What anatomical unit is defined as the structure distal to the last terminal bronchiole?

Acinus Signup and view all the answers

What is a major consequence of bronchiectasis?

Dilated airways with elevated mucus secretion Signup and view all the answers

Which of the following statements about the wall of the bronchus is true?

It contains respiratory epithelium, lamina propria, smooth muscle, and cartilage. Signup and view all the answers

Which type of tissue increases as bronchi undergo multiple branchings?

Smooth muscle and elastic tissue Signup and view all the answers

Which of the following statements is false regarding respiratory bronchioles?

They are lined with ciliated epithelium. Signup and view all the answers

What happens to goblet cells as one moves down the respiratory tract?

They decrease in number. Signup and view all the answers

Study Notes

Respiratory Epithelium

Bronchi divide into bronchioles, then membranous bronchioles, and finally terminal bronchioles
Conducting to respiring epithelium
The respiratory system can be split into two sections: conducting and respiring
Conducting portion serves to get air to the respiring portion
Conducting system includes: trachea, bronchi, and bronchioles
Trachea has cartilage rings that are C-shaped
Bronchi start with cartilage rings which transition to smooth muscle
Bronchioles contain no cartilage and have smooth muscle, lining with respiratory epithelium

Respiratory Bronchioles

Respiratory bronchioles are the transition zone between the conducting airways and the gas-exchanging alveoli
Branching occurs to form alveolar ducts and sacs
Cilia in the respiratory bronchioles disappear distally
Respiratory bronchioles have alveoli along their walls. Alveoli increase in number as the respiratory bronchioles get more distal.

Alveolar Ducts and Sacs

Back-to-back alveolar openings along the walls of alveolar ducts
Smooth muscle between alveolar openings looks like knobs.
Alveolar ducts open into alveolar sacs

Acinus

The acinus is the functional unit of the lung.
Consists of the terminal bronchiole, respiratory bronchiole, alveolar duct, and alveolar sacs

Alveoli

Tiny air sacs at the end of the respiratory bronchioles
Walls are thin to allow for gas exchange between air and blood
Separated by interalveolar septae, which contain capillaries.
Lined by Type I cells (thin, flat squamous cells), Type II cells (produce surfactant), and alveolar macrophages
Type I cells cover 95% of alveolar surface, Type II cells cover 5% of alveolar surface

Surfactant

Surfactant is made by Type II pneumocytes and decreases surface tension in alveoli. This prevents alveoli from collapsing during expiration.
Decreases surface tension in alveoli, requiring less pressure to keep them open
If there is no or low surfactant, alveoli collapse.
Composed of phospholipids and proteins

Pulmonary Alveolar Macrophages

Found on the surface of alveoli and within the lumen of alveoli
Derived from blood monocytes
Remove debris and particles that escape mucus and cilia in the conducting portion of the respiratory tract
Also called "dust cells"

Interstitium

Connective tissue between the alveoli
Consists of the basement membrane of the endothelial and epithelial cells, collagen and elastic fibers, fibroblasts and a few mononuclear cells

Respiratory Blood Supply

The lung receives a dual arterial supply
Pulmonary arteries are low pressure and branch alongside the bronchi and bronchioles
Pulmonary arteries divide into capillary networks in the alveolar wall
Bronchial arteries are high pressure and originate from the aorta
Bronchial arteries branch alongside the bronchi to the respiratory bronchioles

Parietal and Visceral Pleura

The outer surface of the lung and the inner surface of the thoracic cavity are covered by the pleura
Parietal pleura lines the thoracic cavity
Visceral pleura covers the lungs
Serous membranes consist of simple squamous epithelial cells called mesothelium plus a thin layer of connective tissue
The pleural cavity contains serous fluid made by the pleura

Clinical Correlations

Injury to Type I pneumocytes can lead to pulmonary edema
Smoking can lead to "smokers’ macrophages"
Fibrosis in ARDS can cause thickened hyaline membranes and interstitial fibrosis
Bronchiectasis is a condition where the airways are dilated, mucus secretion and inflammation are increased.

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Description

Test your knowledge on the structure and function of the respiratory epithelium, including bronchi, bronchioles, and alveolar ducts. This quiz covers how air travels through the conducting and respiring portions of the respiratory system. Explore the key features from trachea to alveoli, and understand their transitions.