Respiratory System (Anatomy & Physiology)

What is external respiration?

Oxygen moves from the atmosphere into the lungs and then into the bloodstream; carbon dioxide moves from the blood into the lungs and then the atmosphere.

What is internal respiration?

Oxygen moves from the blood into the tissues, while waste products move from the tissues into the blood.

According to the study pack, what percentage of inspired air is nitrogen?

79%.

According to the study pack, what percentage of expired air is nitrogen?

79%.

What percentage of oxygen is in inspired air according to the study pack?

20%.

What percentage of oxygen is in expired air according to the study pack?

16%.

What percentage of carbon dioxide is in inspired air according to the study pack?

0.04%.

What percentage of carbon dioxide is in expired air according to the study pack?

4%.

How does water vapour in expired air compare with inspired air?

Expired air is saturated with water vapour, shown as about 6%; inspired-air water vapour varies with humidity.

What structures are listed as parts of the respiratory system?

Nose, nasal cavity, pharynx, larynx, trachea, bronchi and bronchioles, and lungs.

What are the three regions of the nasal cavity listed in the study pack?

Vestibular region, respiratory region and olfactory region.

What epithelial features help the nose and nasal cavity filter inhaled air?

Ciliated columnar epithelium and goblet cells.

How does the nasal cavity moisten inhaled air?

The glandular lining of the nasal chamber makes the air moist.

How do the nasal conchae help condition inhaled air?

They increase surface area and are highly vascular.

Which region of the nasal cavity detects smell?

The olfactory epithelium.

What are the two parts of the palate?

The anterior hard palate and the posterior soft palate.

What is the uvula?

A curved fold of muscle covered with mucous membrane.

How long is the pharynx according to the study pack?

About 12–14 cm.

From where to where does the pharynx extend?

From the base of the skull to the level of C6.

Where is the pharynx located?

Behind the nose and mouth; it is wider at its upper end.

What infection-fighting tissue does the pharynx contain?

Lymphoid tissue, including the tonsils.

What are the three parts of the pharynx?

Nasopharynx, oropharynx and laryngopharynx.

Where does the nasopharynx begin?

At the rear of the nasal cavity.

What epithelium lines the nasopharynx, and what is its function?

Pseudostratified columnar epithelium; it functions as an airway.

What are the boundaries of the oropharynx in the study pack?

From the soft palate to the hyoid bone.

What epithelium lines the oropharynx?

Stratified squamous epithelium.

What passes through the oropharynx?

Food and air.

What are the boundaries of the laryngopharynx in the study pack?

From the hyoid bone to the cricoid cartilage.

What epithelium lines the laryngopharynx?

Stratified squamous epithelium.

What happens to the upper respiratory and digestive tracts after the laryngopharynx?

They diverge; the rear of the laryngopharynx merges with the oesophagus to continue the digestive tract.

What are the functions of the pharynx listed in the study pack?

Passageway for air and food; warms and humidifies air; protection through tonsils; projects speech; taste.

What is another name for the larynx?

The voice box.

Which vertebral levels does the larynx span according to the study pack?

From the level of the fourth cervical vertebra to the sixth cervical vertebra.

What does the larynx connect?

The laryngopharynx with the trachea.

Why is the larynx called the voice box?

It contains the vocal cords.

What happens if solid food enters the larynx, according to the study pack?

It is expelled by a violent cough.

Why is the larynx larger in males after puberty?

The study pack notes that it becomes larger in males following puberty.

Which single laryngeal cartilages are listed?

One thyroid cartilage, one cricoid cartilage and one epiglottis.

Which paired laryngeal cartilages are listed?

Two arytenoid, two corniculate (cartilages of Santorini), and two cuneiform cartilages.

What are the main functions of the larynx?

Sound production, air passage, humidifying/filtering/warming inhaled air, and protecting the lower respiratory tract.

How does the epiglottis protect the lower respiratory tract?

During swallowing, it closes over the larynx to help prevent food entering the trachea.

What is the trachea commonly called?

The windpipe.

Where does the trachea lie in relation to the oesophagus?

In front of the oesophagus.

What dimensions for the trachea are given in the study pack?

About 2.5 cm in diameter and 11 cm long.

Between which vertebral levels does the trachea extend according to the study pack?

From C6 to T6.

What supports the trachea?

A series of 16–20 C-shaped hyaline cartilage rings that are incomplete posteriorly.

What epithelium lines the trachea?

Pseudostratified ciliated columnar epithelium with mucus-secreting goblet cells.

What are the functions of the trachea?

Conducts air to the bronchi, provides support, moves particles and excess mucus upwards, enables the cough reflex, and warms, humidifies and filters air.

In which direction do tracheal cilia beat?

Upwards, carrying foreign particles and excess mucus towards the pharynx.

How does the trachea divide?

Into the right and left primary bronchi.

How does the study pack compare the right and left primary bronchi?

The right bronchus is shorter and broader (about 2.5 cm); the left is longer and narrower (about 5 cm).

What is the branching sequence from primary bronchi towards the gas-exchange region?

Primary bronchi → secondary bronchi → tertiary bronchi → bronchioles → respiratory bronchioles → alveolar ducts → alveoli.

How are the walls of the primary bronchi supported?

By incomplete cartilage rings, like the trachea.

What replaces the cartilage rings within the lungs?

Small plates of cartilage; smooth muscle also encircles the bronchi.

What do respiratory bronchioles lead into?

Alveolar ducts, which end in clusters of alveoli.

What is an alveolar sac?

A common chamber into which several alveoli may open.

How many lungs do humans have?

Two.

What is the general shape of each lung?

Cone-shaped.

Where is the apex of each lung located?

Close to the level of the first rib.

Where is the base of each lung located?

On the superior aspect of the diaphragm.

How many lobes does the right lung have?

Three.

How many lobes does the left lung have, and what feature does it contain?

Two lobes and a cardiac notch.

What is the pleura?

A double-layered sac enclosing each lung.

What is the visceral pleura attached to?

The lungs.

What is the parietal pleura attached to?

The thoracic wall and diaphragm.

What fills the pleural cavity?

Pleural fluid.

State Boyle's law as applied to respiration.

At constant temperature, increasing the volume of a given amount of gas decreases its pressure, and vice versa.

During inspiration, what happens to lung volume and pressure?

Lung volume increases and pressure inside the lungs decreases.

During expiration, what happens to lung volume and pressure?

Lung volume decreases and pressure inside the lungs increases.

What does Henry's law state in the study pack?

At constant temperature, the amount of gas that dissolves in a liquid is directly proportional to the gas's partial pressure and its solubility.

What is diffusion?

Movement of gases from a region of higher concentration to a region of lower concentration.

Where does gas diffusion occur in the lungs?

Between the alveoli and the capillaries.

What is tidal volume (TV)?

The amount of air inhaled or exhaled during a normal, restful breath.

What is inspiratory reserve volume (IRV)?

The extra volume of air that can be forcibly inhaled after a normal inspiration.

What is expiratory reserve volume (ERV)?

The extra volume of air that can be forcibly exhaled after a normal expiration.

What is residual volume (RV)?

The volume of air remaining in the lungs after maximal forced exhalation.

What is vital capacity (VC)?

The maximum total volume of air that can be exhaled after a maximal inhalation.

What is total lung capacity (TLC)?

The total volume of air the lungs can hold after maximal inhalation.

What breathing rate is given in the study pack?

12–18 breaths per minute.

Is inspiration an active or passive process in the study pack?

An active process.

What happens to the diaphragm during inspiration?

Its muscles contract and the diaphragm flattens, lowering its dome.

What happens to the ribs during inspiration?

External intercostal muscles contract and the ribs move outwards, forwards and upwards.

Why does air enter the lungs during inspiration?

Thoracic cavity volume increases, pressure decreases, and air flows in.

Is normal expiration described as active or passive in the study pack?

A passive process.

What happens to the diaphragm and ribs during normal expiration?

The diaphragm relaxes and becomes dome-shaped; the intercostal muscles relax and the ribs return towards their resting position.

What is the pause in breathing?

The gap between inspiration and expiration.

What happens to intrapleural and intra-alveolar pressure during inspiration?

Both decrease, according to the study pack.

How is forced expiration described?

As a voluntary, active process.

Which abdominal muscles are listed as contracting during forced expiration?

External oblique, internal oblique, transverse abdominis and rectus abdominis.

Which rib muscles are listed as contracting during forced expiration?

Internal intercostal muscles and triangularis sterni muscles.

What is alveolar ventilation?

The amount of fresh air reaching the alveoli for gas exchange.

What is pulmonary perfusion?

The volume of blood flow passing through the capillaries around the alveoli.

What does the ventilation-perfusion (V/Q) ratio describe?

How well airflow and blood flow are balanced in the lungs to maximise gas-exchange efficiency.

Why does surface area affect external respiration?

A larger available lung surface area allows more gas to exchange at once.

How does membrane thickness affect gas diffusion?

A thinner alveolar-capillary barrier allows faster diffusion of gases.

What role do partial-pressure gradients play in gas exchange?

Differences in gas pressure between the lungs and blood drive oxygen and carbon dioxide across the membrane.

How does gas solubility affect respiratory diffusion according to the study pack?

More soluble gases cross the respiratory membrane much faster.

What does elastase do to alveoli?

It breaks down elastic tissue, damages alveolar walls and decreases surface area; the study pack links this to emphysema.

What oxygen partial pressure in air on plains is given in the study pack?

158 mm Hg.

What oxygen partial pressure in the alveoli is given after inspired air mixes with residual air?

104 mm Hg.