Chapter 16: The Respiratory System: Pulmonary Ventilation

external respiration

exchange of gases between lungs and blood

internal respiration (cellular respiration)

the exchange of gases within the cells of the blood and tissues

pulmonary ventilation

movement of air into and out of the lungs

upper airways

nose, mouth, pharynx, larynx

respiratory tract

The passageway that makes breathing possible.

series of branching tubes that conduct air to and from the respiratory zone for gas exchange

conducting zone

Includes respiratory passageways, cleanses, humidifies and warms incoming air

respiratory zones

respiratory bronchioles, alveolar ducts, alveoli

pharynx

the membrane-lined cavity behind the nose and mouth, connecting them to the esophagus.

larynx

voice box; passageway for air moving from pharynx to trachea; contains vocal cords

trachea

a large membranous tube reinforced by rings of cartilage, extending from the larynx to the bronchial tubes and conveying air to and from the lungs; the windpipe.

primary bronchi

The first branches of the trachea. There are two primary bronchi, one for each lung.

secondary bronchi

branches of the primary bronchi that lead to each lobe of the lung; also called lobar bronchi

tertiary bronchi

branches of the secondary bronchi that divide into bronchioles; also called segmental bronchi

bronchioles

smallest branches of the bronchi

terminal bronchioles

smaller than 0.5 millimeter and these mark the end of the conducting zone

dead space

The portion of the tidal volume that does not reach the alveoli and thus does not participate in gas exchange.

goblet cells

a column-shaped cell found in the respiratory and intestinal tracts, which secretes the main component of mucus.

ciliated cells

can catch dust and microbes and move them out of the breathing system

mucus escalator

The upward movement of mucus in the lungs caused by the coordinated movement of cilia.

respiratory bronchioles

branches of the terminal bronchioles that subdivide into several alveolar ducts

alveolar ducts

the subdivisions of the respiratory bronchioles, which terminate in the alveolar sacs that resemble clusters of grapes.

alveolar sacs

two or more alveoli that share a common duct or opening

alveoli

tiny sacs of lung tissue specialized for the movement of gases between air and blood

alveolar pores

Small opening in the wall of an air sac that permits air to pass from one alveolus to another

gas exchange

the process of obtaining oxygen from the environment and releasing carbon dioxide

pulmonary circuit

system of blood vessels that carries blood between the heart and the lungs

Type I alveolar cells

allow rapid diffusion of gases through their thin membranes

Type II alveolar cells

secrete a chemical known as surfactant.

surfactant

any substance that interferes with the hydrogen bonding between water molecules and thereby reduces surface tension

alveolar macrophages

dust cells

respiratory membrane

the barrier between the alveolar air and blood

thoracic cavity

cavity housing lungs and heart

pleura

double-layered membrane surrounding each lung

pleural sac

the thin, double-walled serous membrane that surrounds the lungs

visceral pleura

parietal pleura

outer layer of pleura lying closer to the ribs and chest wall

intrapleural space

Space between the two membranes, visceral pleura and parietal pleura, that cover the lungs.

pressure gradients

-difference between atmospheric and intrapulmonary pressure

-created by changes in volume of thoracic cavity

inspiration (inhalation)

breathing air into the lungs

expiration (exhalation)

breathing out, expelling air from lungs

atmospheric pressure (Patm)

pressure exerted by the air surrounding the body

Intra-alveolar pressure (Palv)

pressure of the air in the alveoli; varies with each phase of respiration

Intrapleural pressure (Pip)

pressure within the pleural cavity

transpulmonary pressure

difference between intrapulmonary and intrapleural pressure

pneumothorax

air in the pleural cavity caused by a puncture of the lung or chest wall

Boyle's Law

A principle that describes the relationship between the pressure and volume of a gas at constant temperature

ideal gas law

the relationship PV=nRT, which describes the behavior of an ideal gas

diaphragm

Large, flat muscle at the bottom of the chest cavity that helps with breathing

external intercostals

elevates ribs during inspiration

internal intercostals

depresses ribs

resistance

the resistance of the respiratory tract to airflow during inhalation and exhalation.

lung compliance

measure of change in lung volume that occurs with given change in trans pulmonary pressure

elasticity

the rebound of the lungs after having been stretched by inhalation, or rather, the ease with which the lung rebounds. With inhalation, the intrapleural pressure (the pressure within the pleural cavity) of the lungs decreases

surface tension of alveolar fluid

draws alveoli to their smallest possible size

infant respiratory distress syndrome

lung condition most commonly found in premature infants that is characterized by tachypnea and respiratory grunting

bronchoconstriction

reduction in diameter of a bronchus

autonomic nervous system

the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.

asthma

A chronic allergic disorder characterized by episodes of severe breathing difficulty, coughing, and wheezing.

COPD (chronic obstructive pulmonary disease)

A group of lung diseases that block airflow and make it difficult to breathe.

chronic bronchitis

a condition in which the bronchi in the lungs are constantly swollen and clogged with mucus

emphysema

A serious disease that destroys lung tissue and causes breathing difficulties.

spirometry

a measurement of breathing (or lung volumes)

lung volumes

tidal volume, inspiratory reserve volume, expiratory reserve volume, residual volume

tidal volume (VT)

Amount of air that moves in and out of the lungs during a normal breath

inspiratory reserve volume

Amount of air that can be forcefully inhaled after a normal tidal volume inhalation

expiratory reserve volume

Amount of air that can be forcefully exhaled after a normal tidal volume exhalation

residual volume

Amount of air remaining in the lungs after a forced exhalation

lung capacities

measurements that are the sum of two or more lung volumes

inspiratory capacity

tidal volume + inspiratory reserve volume

vital capacity

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

functional residual capacity

expiratory reserve volume + residual volume

total lung capacity

vital capacity + residual volume

obstructive pulmonary diseases

emphysema, chronic bronchitis, asthma

forced expiratory volume

amount of gas expelled during specific time intervals of FVC

anatomical dead space

the conducting zone; airways that fill with air but cannot perform gas exchange

minute ventilation

The volume of air moved through the lungs in 1 minute minus the dead space; calculated by multiplying tidal volume (minus dead space) and respiratory rate; also referred to as minute volume.

alveolar ventilation

The volume of air that reaches the alveoli. It is determined by subtracting the amount of dead space air from the tidal volume.