Respiratory System: Anatomy, Mechanics, and Volumes

Flashcards covering respiratory anatomy, lung capacities, mechanics of inspiration and expiration, and gas exchange.

What are the primary functions of the respiratory system?

To obtain oxygen ($O_2$) for use by the body's cells and to eliminate the carbon dioxide ($CO_2$) that the cells produce.

What three main structural components are included in the respiratory system?

The respiratory airways leading into the lungs, the lungs themselves, and the structures of the chest.

Which anatomical structures comprise the respiratory airways in sequential order?

Nose, nasal passages, pharynx, larynx, trachea, bronchus, bronchioles, and alveoli.

Why is the left lung smaller in size than the right lung?

The left lung is smaller due to the positioning of the heart.

What double-layered membrane surrounds the lungs, and what is the role of the fluid within it?

The lungs are enclosed in the pleural sac; the pleural fluid inside lubricates the membrane and allows the lungs to expand and contract.

What components make up the internal tissue of the lungs?

Bronchioles, alveoli, pulmonary blood vessels, and large quantities of elastic connective tissue.

What is the shape and estimated total surface area of the lungs?

They are shaped like a blunt cone with a tip pointing superiorly and a base inferiorly, possessing a surface area of $100\,\text{m}^2$.

What functions does the nasal cavity perform before air enters the lungs?

It filters, humidifies, and moistens the air.

What is the function of the pharynx and which two pathways lead off from it?

It is a chamber connecting the nose, mouth, and throat as a common passageway for air and food; air travels into the trachea (windpipe) to the lungs, and food passes to the stomach via the oesophagus.

What occurs to the trachea and oesophagus during swallowing?

The trachea is closed off by the glottis, while the oesophagus remains closed except during the act of swallowing.

What is the larynx and how does it prevent food from entering the trachea during swallowing?

The larynx (voice box) lies below the pharynx and contains vocal folds for speech; during swallowing, it rises to bend the epiglottis over the glottis, and the vocal folds close off the entrance to the trachea.

What is the physical structure and cartilage composition of the trachea?

It is a tough, flexible tube or "windpipe" made up of "c"-shaped cartilage rings.

How does the bronchial tree divide from the trachea into the lungs?

The trachea divides into the right and left primary bronchi, which enter the right and left lungs and continue branching into narrower, shorter, and more numerous airways called bronchioles.

What are alveoli and how does their structure enable gas exchange?

Alveoli are small, thin-walled, inflatable air sacs clustered at the ends of bronchioles, encircled by pulmonary capillaries, and are a single cell thick to allow diffusion of $O_2$ and $CO_2$.

What is the distinction between external respiration and internal respiration?

External respiration is the exchange of gases between the atmosphere and the blood, while internal respiration is the exchange of gases between the blood and the cells of the body.

What volume of air is typically present in the lungs during the respiratory cycle, and what are the maximum expansion and emptying limits?

Lungs normally contain about $2$ to $2.5\,\text{L}$ of air; they can be filled to more than $5.5\,\text{L}$ or emptied to about $1\,\text{L}$.

What is the average resting respiratory rate and which part of the nervous system controls it?

Respiratory rate averages $12\text{--}18$ breaths per minute and is an automatic process controlled by the lower brainstem.

Why do the lungs depend on pressure changes in the thoracic cavity to inflate and deflate?

The lungs are not directly attached to any muscle, meaning they cannot directly expand or contract on their own.

Which muscular actions and pressure changes drive inspiration (breathing in)?

Inspiration is always active; contraction of the diaphragm (moving downward) and external intercostals (elevating ribs) increases thoracic volume, creating a decrease in lung pressure that draws air in.

How does expiration occur during quiet breathing compared to exercise?

During quiet breathing, expiration is passive as the diaphragm relaxes upward and intercostals relax, increasing lung pressure to force air out; during exercise, expiration becomes more active.

How is Boyle's law described in relation to respiration mechanics?

A gas will move from an area of high pressure to that of an area of low pressure.

What concentration gradients drive gas exchange during external respiration in the lungs?

Oxygen moves from high concentration in the alveoli to low concentration in pulmonary capillaries, while carbon dioxide moves from high concentration in the capillaries to low concentration in the alveoli.

What concentration gradients drive gas exchange during internal respiration in the tissues?

Oxygen moves from high concentration in systemic capillaries into low concentration in tissues, while carbon dioxide moves from high concentration in tissues into low concentration in the blood.

What are the characteristics of optimal breathing?

Diaphragmatic, nasal, deep, smooth, even, without sound, and without pause.

Which six general factors affect breathing according to the lecture?

Age, gender, posture, stress, smoking, and respiratory infections.

What occurs during asthma and what are common triggers in children and adolescents?

It is an obstructive lung disorder where airflow through conducting airways is limited; in children and adolescents, it is linked to allergic reactions to pollen, foods, dust, animal fur, exercise, and cold air.

How does pneumonia affect respiratory function?

It causes inflammation of the lungs that fills alveoli with mucus and fluid, impairing gas exchange and affecting whole-body function.

What is Tidal Volume and what is its resting value?

The volume of air inspired or expired per breath, which is approximately half a litre ($0.5\,\text{L}$) at rest.

What is Total Lung Capacity and what is its approximate volume?

The volume of air within the lungs after maximum inspiration, approximately $5\,\text{litres}$.

What is Residual Volume and why is it necessary?

The leftover air in the lungs after expiration that prevents lungs from collapsing; it increases if fitness declines or as a result of smoking.

What is Vital Capacity and how does exercise influence it?

The maximum amount of air that can be breathed in and out in one breath; it increases because exercise requires more oxygen delivery to working muscles.

What is the difference between Inspiratory Reserve Volume and Expiratory Reserve Volume?

Inspiratory Reserve Volume is the extra air that can be inspired after a normal inspiration, whereas Expiratory Reserve Volume is the extra air that can be expired after a normal expiration.

What is Respiratory Minute Volume?

The volume of air that can be breathed in and out in one minute.