Chapter 22: The Respiratory System

Merged flashcards from Chapter 22, McGraw Hill Anatomy and Physiology Tenth Edition, by Kenneth S. Saladin.

Respiratory system

Organ system that takes in and expels air from the body

Respiration (breathing)

Ventilation of the lungs

Respiratory system functions

• Gas exchange (O₂ and CO₂)

• Acid-base balance (CO₂ pH regulation)

• Blood and lymph flow and filtration (pressure)

• Platelet production (transfer to blood)

• Blood pressure regulation

• Abdominal content expulsion

• Olfaction (smell)

• Communication (speech)

Respiratory system organs

• Nose

• Pharynx

• Larynx

• Trachea

• Bronchi

• Lungs

Respiratory system zones

• Conducting zone (airflow)

• Respiratory zone (gas exchange)

• Upper respiratory tract (nose to larynx)

• Lower respiratory tract (trachea to lungs)

Conducting zone

Area of the respiratory system that serves only for airflow, no gas exchange (nostrils)

Respiratory zone

Areas of the respiratory system that participate in gas exchange (alveoli, other structures)

Upper respiratory tract

Area of the respiratory system from the nose to the larynx

Lower respiratory tract

Area of the respiratory system from the trachea to the lungs

Nose

Part of the respiratory system made of cartilage that warms, cleanses, and humidifies air while detecting odors and amplifying voice through chambers

Ala nasi

Flared portion at the lower end of the nose made of specialized cartilage

Nasal septum

Structure that divides the nasal cavity into the left and right nasal fossae; made of cartilage

Vestibule

Small chamber inside the nostrils with guard hairs that block insects and debris from entering the nose

Nasal conchae (turbinates)

Tissue that vibrates the vestibule from behind to move mucus

Goblet cells

Mucus-producing cells

Ciliated cells

Cells with motile cilia that move mucus

Olfactory epithelium

Tissue within the nose involved in smell through chemical detection

Erectile tissue (swell body)

Tissue that restricts airflow to each nostril 30 to 60 minutes at a time by swelling with blood to allow recovery from drying

Pharynx

Muscular funnel extending about 13 cm that is divided into three regions:

1. Nasopharynx

2. Oropharynx

3. Laryngopharynx

Nasopharynx

Part of pharynx that receives the auditory tubes and contains the pharyngeal tonsil

Oropharynx

Part of the pharynx that contains the palatine tonsils

Laryngopharynx

Part of the pharynx that is posterior to the larynx and begins the esophagus

Larynx

A cartilaginous chamber to keep food and drink out of the airway and produce sound

Epiglottis

Flap of tissue over the top of the larynx that prevents airway occlusion

Thyroid cartilage

Shield-shaped and largest laryngeal cartilage; contains the laryngeal prominence (Adam’s apple) which is larger in males due to testosterone

Vestibular folds

Folds of the larynx that play no role in speech but close the larynx during swallowing; supported by vestibular ligaments

Vocal cords (vocal folds)

Folds of the larynx that produce sound when air passes between them, contains vocal ligaments to endure vibration and contact alongside muscles to create sound

Gender vocal cord differences

Males have longer and thicker vocal cords that vibrate slower and produce lower-pitched sounds

Trachea (windpipe)

Rigid tube that connects the larynx to the bronchi; is anterior to the esophagus and supported by cartilage rings

Mucociliary escalator

Mechanism for debris removal to move particle-trapping mucus upwards towards pharynx to be swallowed

Tracheotomy

A temporary opening in the trachea with a tube to allow airflow, preventing asphyxiation, but can dry out mucous membranes and increase infection risk by bypassing the nasal cavity

Intubation

Directly introducing air into the trachea with a ventilator; air is filtered and humidified

Base

The broad, concave portion of the lung resting on the diaphragm

Apex

Tip of the lung that projects above the clavicle

Costal surface

Part of the lung pressed against the ribcage (costals)

Mediastinal surface

Part of the lung that faces medially toward the heart

Hilum

Slit through the lung recieving the main bronchus, blood vessels, lymphatics, and nerves

Lobe diffferences

Right lung has three lobes (superior, middle, and inferior) while left lung has two (superior and inferior)

Cardiac impression

The left lung’s indentation to accomodate the heart

Bronchial tree

A branching system of air tubes in each lung

Main bronchi (primary bronchi)

Bronchi that arises from the fork of the trachea; right is wider and more vertical than left leading to higher aspiration rates

Lobar bronchi (secondary bronchi)

Bronchi branhcing off into each lobe of the lung into to superior, middle, and inferior lobar bronchi (superior and inferior in the left lung)

Segmental bronchi (tertiary bronchi)

Bronchi that branch off the lobar bronchi into smaller segments

Bronchioles

Continuations of the bronchi without supportive cartilage, <1 mm in diameter

Terninal bronchioles

The final branches of the conducting zone and bronchi before the alveoli; no mucous glands or goblet cells (instead moving on mucociliary escalator)

Respiratory bronchioles

Bronchioles that branch off terminal bronchioles with alveoli budding from the walls for gas exchange; considered part of the respiratory zone

Alveolar sacs

Clusters of alveoli around a central space

Alveoli

Microscopic air patches in the lungs about 0.2 to 0.5 mm in diameter for gas exchange

Alveolar macrophages (dust cells)

One of the most numerous cells in the lung, they wander the alveoli and connective tissue by phagocytizing (“eating”) dust particles then go up the mucociliar escalator

Respiratory membrane

The thin barrier between the alveolar air and blood where gases are exchanged across

Pulmonary circuit pathway

After passing through pulmonary valve:

1. Pulmonary trunk

2. Pulmonary arteries

3. Lobar arteries

4. Capillaries around alveoli

5. Pulmonary veins

Then to left atrium

RIght-to-left shunt

Blood flow pattern in the heart where some deoxygenated blood passes to the oxygenated left ventricle, diluting oxygen content

Alveolar pressure

Lower to prevent accumulation and increase aeration

Pleura

Serous membrane that lines the thoracic wall and forms the surface of the lung, split into the visceral (surface) and parietal (medastinal) pleura

Visceral pleura

Pleura that forms the surface of the lung

Parietal pleura

Pleura that adheres to the mediastinum and inner surface of the rib cage

Pleural cavity

The potential space between the pleurae for friction reduction and pressure maintenance

Inspiration

The act of inhalation

Expiration

The act of exhalation

Respiratory cycle

One complete breath measuring the cycle of inhalation and expiration; relies on pressure differences

Quiet respiration

Effortless and automatic breathing while at rest

Forced respiration

Deep or rapid breathing during an activity

Diaphragm

The prime mover of respiration; contraction flattens this muscle to enlarge the thoracic cavity and pull air in

Intercostal muscles

Muscles located between the ribs (costals) that contribute to thoracic contraction and enlargement

Accessory muscles

Muscle like the erector spinae, sternocleidomastoid, scalenes, pectoralis, and serratus that act during forced respiration, deep inspiration

Valsava maneuver

Breathing technique used to help expel contents of the abdomen

Central chemoreceptors

Brainstem neurons that respond to cerebrospinal fluid pH changes which reflect CO₂ levels for respiration stability

Peripheral chemoreceptors

Receptors in the carotid and aortic bodies that respond to pH, gas content of blood

Stretch receptors

Receptors in the bronchi, bronchioles, and visceral pleura that regulate and respond to inflation

Inflation reflex (Hering-Breuer reflex)

Reflex triggered by excessive inflation that inhibits inspiratory neurons and stops inspiration

Irritant receptors

Nerves that respond to external irritants such as smoke or dust to cause reflexes like bronchoconstriction, shallow berathing, apnea, or coughing

Atmospheric pressure

The weight of the air on Earth; lower at higher elevations

Intrapulmonary pressure

Air pressure within the lungs

Boyle’s law

At a constant temperature, the pressure of a gas is inversely proportional to volume

More lung volume results in lower pressure; less lung volume results in higher pressure

Intrapleural pressure

The slightly negative pressure between the two pleural layers to allow for expansion

Charles’s law

At a constant pressure, the volume of a gas is directly proportional to temperature

Higher air temperatures expand the lungs further as it is warmed

Pneumothorax

The presence of air in the pleural cavity where the thoracic wall is punctured and negative intrapleural pressure is loss, allowing lung collapse

Atelectasis

The collapse of part or all of a lung that can also result from airway obstruction or clots

Bronchodilation

The increase in diameter of a bronchus or bronchiole for increased airflow; can be caused by epinephrine or sympathetic stimulation

Bronchoconstriction

The decrease in diameter of a bronchus or bronchiole for decreased airflow; caused by histamine, cold air, chemicals, or parasympathetic nerves

Pulmonary compliance

The ease with which the lungs can expand given a change in pressure for lung volume

Alveolar ventilation rate

The amount of air ventilating alveoli per minute

Spirometry

Measuing pulmonary ventilation to assess disease severity

Spirometer

Device used to make spirometry measurements to recapture breath and record breathing variables

Tidal volume (TV)

The volume of air inhaled and exhaled in one cycle of breathing

Inspiratory reserve volume (IRV)

Air in excess of tidal volume that can be inhaled with maximum effort

Expiratory reserve volume (ERV)

Air in excess of tidal volume that can be exhaled with maximum effort

Residual volume

Air remaining in lungs that cannot be exhaled even with maximum effort; allows some gas exchange before next breath of fresh air arrives

Vital capacity

Total amount of air that can be inhaled then exhaled with maximum effort

Inspiratory capacity

Maximum amount of air that can be inhaled after a normal tidal expiration

Functional residual capacity

Amount of air remaining in lungs after a normal tidal expiration

Total lung capacity

Maximum amount of air the lungs can contain

Restrictive disorders

Disorders that result in a reduction in pulmonary compliance (inflation); includes black lung disease and tuberculosis

Obstructive disorders

Disorders that interfere with airflow through airway obstruction; makes inhalation or exhalation more difficult and includes asthma and chronic bronchitis

Emphysema

Disorder commonly caused by smoking that combines elements of restrictive and obstructive disorders

Air composition

• 78.6% N

• 20.9% O₂

• 0.04% CO₂

• trace amounts of Ar, Ne, He, CH₄, O₃

Dalton’s law

The total atmospheric pressure is the sum of the contributions of the individual gases

Partial pressure

The separate contribution of each gas to pressure in a mixture

Alveolar gas exchange

The movement of O₂ and CO₂ across the respiratory membrane, using a film of water to cover the epithelium to dissolve oxygen and diffuse carbon dioxide

Hyperbaric oxygen therapy

Treatment with oxygen at greater than 1 atmosphere of pressure to allow more diffusion into the blood; used to treat gangrene and CO poisoning