Respiratory System Function and Anatomy

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Questions and Answers

What is the normal value of tidal volume in a healthy adult?

1200 ml

3300 ml

1000 ml

500 ml (correct)

Which maneuver describes the condition when intra-alveolar pressure falls to -80 mmHg?

Valsalva maneuver

Muller maneuver (correct)

Normal inspiration

Normal expiration

Which type of lung function tests are based on the volume of air flowing in and out of the lungs?

Obstructive lung function tests

Dynamic lung function tests

Volumetric lung function tests

Static lung function tests (correct)

What is the significance of residual volume in the lungs?

It maintains lung contours and allows for gas exchange. Signup and view all the answers

At the end of normal expiration, what is the intra-alveolar pressure?

+1 mmHg Signup and view all the answers

Which lung volume can be expelled forcefully after a normal expiration?

Expiratory reserve volume Signup and view all the answers

What is the definition of transpulmonary pressure?

Difference between intra-alveolar pressure and intrapleural pressure Signup and view all the answers

What is the normal value of expiratory reserve volume in a healthy adult?

1000 ml Signup and view all the answers

What occurs during systole in terms of blood flow?

Blood flow increases. Signup and view all the answers

Which muscles are classified as inspiratory muscles?

Sternocleidomastoid. Signup and view all the answers

What factors contribute to the collapsing tendency of the lungs?

Elastic properties of lung tissue. Signup and view all the answers

How does surfactant assist in lung function?

Decreases surface tension of fluid lining pulmonary alveoli. Signup and view all the answers

What is the intrapleural pressure at the end of normal expiration?

-2 mmHg. Signup and view all the answers

During forced expiration with a closed glottis, what is the intrapleural pressure?

+50 mmHg. Signup and view all the answers

What maintains the inflation of the lungs?

Negative intrapleural pressure. Signup and view all the answers

What happens to the thoracic cavity during expiration?

It contracts. Signup and view all the answers

What two structures does the trachea lead to in the lungs?

Bronchi and bronchioles Signup and view all the answers

What are the tiny air sacs in the lungs called?

Alveoli Signup and view all the answers

What happens to the pressure in the thorax when we inhale?

It decreases Signup and view all the answers

During gas exchange in the lungs, what occurs?

Oxygen passes into the blood and carbon dioxide passes out of the blood Signup and view all the answers

What is the correct pathway through which air travels in the human respiratory system?

Nose, pharynx, trachea, lungs Signup and view all the answers

Which structure is responsible for preventing food from entering the trachea?

Epiglottis Signup and view all the answers

Approximately how many alveoli are found in the human lungs?

300 million Signup and view all the answers

Which factor causes pulmonary blood flow to increase during exercise?

Decreased vascular resistance Signup and view all the answers

Study Notes

Respiratory System Structures and Function

The trachea leads to the bronchi in the lungs.
The tiny air sacs in the lungs are called alveoli.
The epiglottis prevents food from entering the trachea.
Approximately 300 million alveoli are found in human lungs.

Gas Exchange in the Lungs

During gas exchange, oxygen passes into the blood and carbon dioxide passes out of the blood.

Respiratory Pathway

Air travels through the nose, pharynx, trachea, and lungs.

Pressure Changes During Respiration

When inhaling (breathing in), the pressure in the thorax increases.

Regulation of Pulmonary Blood Flow

Pulmonary blood flow is proportional to cardiac output.
Pulmonary blood flow is inversely proportional to vascular resistance.
During inspiration, pulmonary blood vessels are distended due to decreased intrathoracic pressure.
During exercise, vascular resistance decreases, and pulmonary blood flow increases.

Factors Affecting Pulmonary Blood Vessels

Sympathetic nervous system causes vasoconstriction (b2).
Excess carbon dioxide and lack of oxygen cause vasoconstriction.

Gravity and Hydrostatic Pressure

In a standing position, blood pressure is high in the lower extremities and low in parts above the heart.
Blood flow distribution in the lung varies across different zones (apex, zone 2, zone 3, base).

Zones of Blood Flow in the Lungs

Zone 1: Pulmonary capillary pressure is similar to alveolar pressure; zero blood flow.
Zone 2: Alveolar pressure is below pulmonary systolic pressure and above diastolic pressure; intermittent blood flow.
Zone 3: Pulmonary arterial pressure is higher than alveolar pressure; continuous blood flow.

Respiratory Movements

Respiratory muscles include inspiratory muscles (diaphragm and external intercostals) and expiratory muscles (internal intercostals and abdominal muscles).

Mechanisms of Respiration

During inspiration, the diaphragm moves down and the ribs move out, expanding the thoracic cavity.
During expiration, the diaphragm moves up and the ribs move in, compressing the thoracic cavity.

Lung Movement and Pressure

During inspiration, the negative pressure in the thoracic cavity causes lung expansion.
During expiration, the thoracic cavity decreases in size, compressing the lungs and expelling air.

Collapsing Tendency of the Lungs

Factors causing collapse include: elastic lung tissue properties and surface tension of alveolar fluid.
Factors preventing collapse include: negative intrapleural pressure and surfactant.

Surfactant

Surfactant is a lipoprotein complex secreted by type II alveolar epithelial cells.
It lowers surface tension in the alveoli, preventing collapse.

Respiratory Pressures

Two types of pressures are exerted: intrapleural (intrathoracic) and intra-alveolar (intrapulmonary).
Transpulmonary pressure is the difference between alveolar and intrapleural pressures.
Transthoracic pressure is the difference between pleural and atmospheric pressures.
Transthoraco-pulmonary pressure is the difference between alveolar and atmospheric pressures.
Driving pressure is calculated as plateau pressure—PEEP.

Intrapleural Pressure

The pressure within the pleural cavity, normally negative, keeps the lungs inflated.

Intra-alveolar Pressure

The pressure within the alveoli, fluctuating with breathing. It's equal to atmospheric pressure at the end of inspiration and expiration.

Lung Function Tests

Types of lung function tests: static (volume-based) and dynamic (flow-based).
Static tests measure volumes and capacities (e.g., tidal volume, inspiratory reserve volume, expiratory reserve volume, residual volume).

Lung Volumes

Tidal volume: Volume of air inhaled and exhaled during a normal breath.
Inspiratory reserve volume: Maximum volume of air that can be inhaled after a normal breath.
Expiratory reserve volume: Maximum volume of air that can be exhaled after a normal breath.
Residual volume: Volume of air remaining in the lungs after a maximum exhalation.

Other Key Terms

Spirometer: A device used to measure respiratory volumes.

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Description

Test your knowledge on the structures and functions of the respiratory system, including gas exchange, airflow, and regulation of pulmonary blood flow. This quiz covers essential concepts like alveoli, trachea, and pressure changes during breathing.