chapter 22 - the respiratory system

gas exchange (across the alveolar capillary membrane in the lungs)

function of respiratory system

O2 diffuses from the alveoli in the lungs to the blood in the lung capillaries to be delivered to tissue cells to carry out cellular respiration

function of respiratory system

CO2 which is removed from tissue cells, diffuses from the blood in the lung capillaries into the alveoli in the lungs

function of respiratory system

regulation of blood pH (acid-base balance) by changing CO2 levels in blood

function of respiratory system

breathing; movement of air into and out of lungs (part of what system)

pulmonary ventilation, respiratory system

exchange of O2 and CO2 between lungs and blood (part of what system)

external respiration, respiratory system

transport of O2 and CO2 in blood (part of what system)

transport, circulatory system

exchange of O2 and CO2 between systemic blood vessels and tissues (part of what system)

internal respiration, circulatory system

voice production (phonation), olfaction, pressure-related function (ex/coughing, valsalva in lifting)

additional functions of respiratory system

nose and nasal cavity, paranasal sinuses, pharynx

major organs of the upper respiratory

larynx, trachea, bronchi and branches, lungs and alveoli

major organs of the lower respiratory

no gas exchange here; nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles

conducting zone

site for gas exchange; respiratory bronchioles → alveolar ducts → alveolar sacs → alveoli

respiratory zone

entry/exit point for air, functions= filters air, warms air, moistens air

nose and nasal cavity

admit and filter inspired air

external nares

lined with vestibular hairs and mucosa

nasal cavity

superior, middle, inferior; create turbulence for warming and humidification

3 nasal conchae

root, bridge, dorsum nasi, apex, alae, philtrum

external landmarks

nasal bones; septal cartilage (dorsum), alar cartilage
(apex/nares)

framework

anterior cartilage; posterior ethmoid and vomer

nasal septum

pseudostratified ciliated columnar epithelium with goblet cells; cilia sweep mucus posteriorly

lining

produces mucus, warms and moistens the air, lighten the skull, and influence the quality of the voice; frontal, maxillary, sphenoidal, and ethmoidal

paranasal sinuses

lines most of the nasal cavity and conducting airways

pseudostratified ciliated columnar epithelium

beat rhythmically to transport mucus toward the pharynx as a clearance mechanism

cilia

muscular tube subdivided into naso-, oro-, and laryngopharynx according to their locations

pharynx

a common passageway for the respiratory and digestive systems

pharynx

directs flow of air to the larynx (anterior) or food/liquid to the esophagus (posterior)

epiglottis

air passage; auditory tube openings; pharyngeal tonsils (adenoids); soft palate and uvula block during
swallowing

nasopharynx

food and air; palatine and lingual tonsils

oropharynx

directs food to the esophagus (posterior), and air to the larynx (anterior)

laryngopharynx

connecting pharynx to trachea, regulates air volume

cartilaginous structure

known as the voice box because it houses the vocal cords that produce the sound of the voice

larynx

prevent aspiration during swallowing

epiglottis

3 major cartilages

thyroid (largest, unpaired), cricoid (most inferior), epiglottis (unpaired, helps prevent swallowed materials from entering the larynx)

cuneiform, corniculate, aryhenoid

3 paired and posterior cartilages

throid and cricoid cartilages maintain

patency

composed of the vestibular folds, the true vocal cords, and the space between these folds

glottis

produce sound as air passes between them while vibrating

true vocal folds

protect the airway and assist in closure

vestibular folds (false cords)

intermittent release of expired air during opening and closing of glottis

speech

determined by length and tension of vocal cords

pitch

depends upon force of air

loudness

amplify and enhance sound quality

chambers of pharynx and oral, nasal, and sinus

sound is “shaped” into language by muscles of

lips, pharynx, tongue, soft palate

“windpipe”, an air passage that divides at the carina into the right and left main (primary) bronchi

trachea

formed by 16-20 C- shaped hyaline cartilage rings that maintain airway patency, pseudostratified columnar ciliated epithelium + goblet cells

trachea

adjusts diameter for airflow resistance

trachealis muscle

more horizontal than the right because it is displaced by the heart

left primary bronchus

each main stem bronchus divides into __, which subdivides into a __

lobar bronchus, segmental bronchus

right and left leading to each lung

primary bronchi

branching pattern

primary bronchi → secondary (lobar) bronchi → tertiary bronchi → bronchioles → terminal bronchioles → respiratory bronchioles → alveolar ducts → alveolar sacs → alveoli

end of conducting zone

terminal bronchioles

cartilage decreases, bronchi become smaller and smaller as they branch into the lung; smooth muscle increases, regulates airflow

changes with branching

begins at respiratory bronchioles and ends at alveoli, function= site of gas exchange best due to large surface area

respiratory zone

pathway of respiratory zone

respiratory bronchioles → alveolar ducts → alveolar sacs → alveoli

clusters of alveoli for maximal diffusion, and are surrounded by capillary networks

alveolar sacs

channels that connect adjacent alveoli to equalize pressure

alveolar pores

about 300 million with elastic walls, which represent an area of about 70m for gas exchange

alveoli

form most of the alveolar surface, it’s a simple squamous epithelium for gas diffusion (exchange)

type 1 alveolar cells

produce surfactant to decrease surface tension and maintain
the alveoli open to avoid collapse

type II alveolar cells

for debris and pathogens clearance

alveolar macrophages

where gas exchange takes place, mainly formed by the walls of the alveoli and walls of surrounding capillaries

respiratory membrane (alveoli-capillary membrane)

structure of respiratory membrane

surfactant (thin film of fluid lining the alveoli) → alveolar epithelium (type I cells) → basement membrane of alveolar ep. → interstitial space (narrow space in between alveoli and capillary) → basement membrane of the capillary endo. → capillary endothelium

a place for simple diffusion of O2 and CO2

respiratory membrane

exchange O2 and CO2 with the atmosphere

primary role

~70 m of highly permeable epithelium for gas diffusion

surface area

paired organs in thoracic cavity, base rests on diaphragm, apex extends above clavicle; enclosed by the pleurae and attached medially to the mediastinum

lungs

three lobes (superior, middle, inferior); shorter and wider

right lung

two lobes (superior and inferior) plus cardiac notch to accommodate the heart

left lung

where bronchi, vessels, nerves exit/enter lung

hilum

lobes separated by __ , each lobe contains multiple __

fissures, bronchopulmonary

bronchopulmonary segments contains its own

tertiary bronchus and segmental artery

a subdivision of a segment, bordered by interlobular septa and supplied by a large bronchiole

pulmonary lobule

delivers deoxygenated blood to alveoli; returns oxygenated blood to the heart

pulmonary circulation

deoxygenated blood; pulmonary trunk → pulmonary arteries → branches with bronchi → arterioles → pulmonary capillary network at alveoli

pulmonary artery

carry oxygenated blood away from the lungs via the hilum to the left atrium

pulmonary veins

at the lobule level, each lobule receives one _ and one _

arteriole, venule

bronchoconstriction (autonomic control of airway caliber)

parasympathetic

bronchodilation (autonomic control of airway caliber)

sympathetic

from the vagus nerve

parasympathetics

lines the thoracic wall (lateral), mediastinum (medial), and diaphragm (inferior)

parietal pleura

covers the lung surface and extends into the fissures

visceral pleura

between parietal and visceral pleura; contains pleural fluid that reduces friction during breathing, maintains negative pressure to keep the lungs adhered to the thoracic wall during breathing

pleural cavity

the process of moving air into and out of the lungs

ventilation (breathing)

the 2 phases of ventilation

inhalation, exhalation

pressure and volume are inversely related (P1V1= P2V2), as one increases the other decreases; air flows from areas of higher to lower pressure

boyles law

diaphragm contracts → moves down AND external intercostals contract → ribs up → thoracic volume increases → pressure decreases → airflows into lungs; ACTIVE PROCESS

inhalation

intrapleural pressure (pressure in pleural cavity)

always negative (prevents lung collapse)

pressure in the lungs = pressure in the alveoli

intrapulmonary pressure

diaphragm relaxes → moves up → volume decreases → pressure increases → air flows out; PASSIVE PROCESS

exhalation

diaphragm and intercostals (physical factors affecting ventilation)

muscle activity

when the radius of the airway decreases (bronchoconstriction), resistance increases, affecting the airflow (physical factors affecting ventilation)

airway resistance

surfactant lining the alveoli produced by type II cells lowers tension in the alveoli (physical factors affecting ventilation)

alveolar surface tension

compliance is a measure of the lung’s opposition to inflation, low compliance makes inflation difficult

thoracic compliance

normal breathing pattern, diaphragm + external intercostal muscles

quiet (eupnea)

accessory muscles enhance volume changes; scalenes, sternocleidomastoids, internal intercostals, abdominals, obliques

forced breathing (hypernea)

process of measuring volumes of air that move into and out of the respiratory system

spirometry

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

pulmonary volumes

functional residual capacity, inspiratory capacity, vital capacity, total capacity

pulmonary capacities

~ 500 mL per breath (quiet breath)

tidal volume