L 27

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Questions and Answers

What is the primary driving force for air movement during pulmonary ventilation?

Air moves based on the viscosity of the air itself.

Air moves from an area of lower temperature to an area of higher temperature.

Air moves from an area of higher pressure to an area of lower pressure. (correct)

Air moves from an area of lower pressure to an area of higher pressure.

Which physiological change occurs during expiration?

Increased intra-thoracic pressure. (correct)

Increased vertical and antero-posterior diameter of the chest cavity.

Decreased alveolar pressure from 763 mm Hg to 760 mm Hg.

Contraction of the inspiratory muscles.

What aspect of thoric volume is directly affected by the contraction of inspiratory muscles during inspiration?

Increased volume of the thoracic cavity. (correct)

Decreased alveolar pressure.

Decreased total lung capacity.

Increased intra-thoracic pressure.

How does surface roughness affect airflow?

It decreases the airflow due to increased turbulence. Signup and view all the answers

What is the effect of increased alveolar pressure on air movement during expiration?

It forces air from the lungs towards lower pressure areas outside. Signup and view all the answers

Which muscles are primarily responsible for normal expiration?

Elastic recoil of the lungs Signup and view all the answers

During forced expiration, which muscle is NOT typically engaged?

External intercostal muscles Signup and view all the answers

Which process of external respiration involves the movement of air into the lungs?

Pulmonary ventilation Signup and view all the answers

Inhalation is characterized by which of the following?

Requires contraction of skeletal muscles Signup and view all the answers

What is primarily responsible for quiet exhalation?

Relaxation of respiratory muscles Signup and view all the answers

Which of the following statements about respiratory muscles is true?

The diaphragm is the most important muscle for breathing. Signup and view all the answers

Transport of O2 and CO2 occurs via which mechanism?

Movement via RBCs in alveolar capillaries Signup and view all the answers

How does the role of accessory muscles change during respiration?

They become active only during increased respiratory demand. Signup and view all the answers

What is the alveolar pressure during inspiration?

758 mm Hg Signup and view all the answers

What primarily prevents the collapse of the lungs?

Intrapleural pressure Signup and view all the answers

During expiration, what is the approximate value of alveolar pressure?

763 mm Hg Signup and view all the answers

How does transpulmonary pressure change during forced expiration?

It becomes substantially more positive Signup and view all the answers

How does the intrapleural pressure at the apex of the lungs compare to the base during inspiration?

It is more negative Signup and view all the answers

What is pulmonary ventilation primarily concerned with?

The inflow and outflow of air Signup and view all the answers

What happens to the pressure gradient during inspiration?

Pressure inside the lungs decreases Signup and view all the answers

Which statement about pleural pressure during normal breathing is true?

It varies from -5 to -7.5 cm H2O Signup and view all the answers

What structures form the laryngeal inlet?

Anteriorly by the superior margin of the epiglottis and laterally by aryepiglottic folds Signup and view all the answers

Which cartilages are classified as unpaired in the larynx?

Cricoid, thyroid, and epiglottis Signup and view all the answers

Which nerve is responsible for the motor supply of all laryngeal muscles except for the cricothyroid?

Recurrent laryngeal nerve Signup and view all the answers

What is the primary function of the vestibular folds in the larynx?

To protect the airway by closing during swallowing Signup and view all the answers

Which of the following best describes 'lung recoil' in the context of breathing mechanics?

It is influenced by elastic and collagen fibers within the lung tissue Signup and view all the answers

What is the space between the two vocal folds known as?

Rima glottidis Signup and view all the answers

In the mechanics of breathing, which factor primarily affects airflow?

Alveolar pressure changes Signup and view all the answers

Which statement accurately reflects the anatomy of the cavity of the larynx?

The sinus of the larynx intervenes between the vestibular and vocal folds Signup and view all the answers

Study Notes

Respiratory System Overview

The respiratory system is responsible for gas exchange, bringing oxygen into the body and removing carbon dioxide.
Learning outcomes include describing the gross anatomy of the larynx, ventilation and lung mechanics, and factors affecting airflow.

Larynx

The larynx is a hollow, musculo-ligamentous structure with a cartilaginous framework that caps the lower respiratory tract.
It's composed of three large unpaired cartilages (cricoid, thyroid, and epiglottis), and three pairs of smaller cartilages (arytenoid, corniculate, and cuneiform).
It also contains a fibroelastic membrane and intrinsic muscles.
The larynx is located in the anterior midline of the neck, extending from the root of the tongue to the trachea.

Laryngeal Inlet

The laryngeal inlet is formed by the superior margin of the epiglottis and aryepiglottic folds.
Lateral borders are composed of mucosal folds (aryepiglottic folds).
The posterior part is formed by a transverse mucosal fold between the two arytenoids.

Cavity of Larynx

The larynx's interior contains vestibular and vocal folds.
The space between the two vestibular folds is called the rima vestibuli.
The space between the two vocal folds is called the rima glottidis.
The space between vestibular and vocal folds is the ventricle of the larynx or sinus of the larynx.

Summary of Larynx Cavities

The larynx's compartments are defined by folds: the spaces between the aryepiglottic folds form the laryngeal inlet; the spaces between the vestibular folds form the rima vestibuli; and the spaces between the vocal folds form the rima glottidis.
The vestibular folds and vocal folds bound the superior and inferior parts of the laryngeal cavity.
The sinus of the larynx is located between the vestibular and vocal folds.
The space below the vocal folds is called the infraglottic cavity.

Nerve Supply

Sensory nerves above the vocal cord are supplied by the internal laryngeal nerve.
Sensory nerves below the vocal cord are supplied by the recurrent laryngeal nerve.
Motor nerves for all muscles besides the cricothyroid are supplied by the recurrent laryngeal nerve.
Cricothyroid is supplied by the external laryngeal nerve.

Mechanics of Breathing

Breathing mechanics involve pressure, volume, and flow changes during the breathing cycle.
Breathing mechanics are the interplay of forces generated by pressure, volume, and flow changes.
Important components include respiratory muscles, alveolar, pleural, and transpulmonary pressures; lung compliance, and lung recoil.
Work of breathing is also important.

Muscles of Respiration

Muscles of inspiration include the diaphragm and external intercostals.
Accessory muscles include the sternocleidomastoid, scalenes, serratus anterior, and pectoralis minor.
Muscles of expiration include the internal intercostals, external oblique abdominis, internal oblique abdominis, rectus abdominis, and transversus abdominis.
Normal expiration is due to elastic recoil of the lungs and associated structures.
Forced expiration requires additional abdominal muscles.

Functions of Respiratory Muscles

Accessory muscles elevate the sternum, and fix ribs during inspiration.
Principal external intercostal muscles elevate the ribs, increasing the width of the thoracic cavity.
The diaphragm's dome descends, increasing the thoracic cavity's longitudinal dimension.

Alveolar Pressure

Alveolar pressure is the pressure inside the alveoli, vital for inspiration and expiration.
Normal alveolar pressure is equal to atmospheric pressure (760 mm Hg).
During inspiration, alveolar pressure is lower than atmospheric pressure.
During expiration, alveolar pressure is higher than atmospheric pressure.

Pleural and Transpulmonary Pressure

Pleural pressure is the pressure in the space between the lung and chest wall pleura.
Negative pleural pressure prevents lung collapse.
Transpulmonary pressure is the difference between alveolar and pleural pressure.

Pulmonary Ventilation

Pulmonary ventilation involves moving air in and out of the lungs.
Inspiration requires active contractions of respiratory muscles.
Expiration can be passive or active, depending on the need.

Thoracic Volume

Thoracic volume changes during breathing, due to movements of the diaphragm and ribs.
Inspiration increases thoracic volume.
Expiration decreases thoracic volume.

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Description

Explore the key components and functions of the respiratory system, focusing on the anatomy of the larynx and its importance in gas exchange. Understand ventilation mechanics and the factors affecting airflow. Enhance your knowledge about the structure and function of respiratory organs.