chapter 22 respiratory system

Basic functions

Supplies body with oxygen
⚬ Disposes of carbon dioxide

Pulmonary ventilation

Air must be moved into and out of the lungs so
that the gases in the air sacs (alveoli) of the lungs
are continuously replaced

External respiration

Gas exchange must occur between the blood
and air at the lung alveoli

Transport of respiratory gases

Oxygen and carbon dioxide must be transported
between the lungs and the cells of the body

Internal respiration

At the systemic capillaries, gases must be
exchanged between the blood and the
tissue cells

The respiratory and cardiovascular systems are closely coupled, what happens if they fail

the bodys cells begin to die from oxygen starvation

upper respiratory tract

nose, nasal cavity, and paranasal sinuses

lower respiratory tract

trachea, bronchi, and smaller branches

Conducting zone

Respiratory passageways that carry air to the sites of gas exchange
￭ Filter, humidify, and warm incoming air

Respiratory zone

Site of gas exchange in the lungs

the nose

provides an airway for respiration, moistens and warms air

nasal cavity

lies in and posterior to external nose, divided by nasal septum; continuous with nasopharynx

choanae (internal nares)

posterior nasal apertures that connect with nasophraynx

vestibule

the part of nasal cavity that lies just superior to nostrils, lines with skin containing sebaceous and sweat glands with numerous hair follicles

vibrissae (nose hairs)

filter large particles such as insects and lint from inspired air

Olfactory mucosa

Near roof of nasal cavity
￭ Houses olfactory (smell) receptor

Respiratory mucosa

Lines nasal cavity
￭ Mucous membrane that lines the vast majority
of the respiratory passagewa

what does respiratory muscosa consist of

Pseudostratified ciliated columnar epithelium

what nerve supplies respiratory mucosa

CN V (trigeminal nerve)

superior and middle nasal conchae is part of

ethmoid bone

nasal conchae: particulate matter

Deflected to mucus-coated surfaces

nasal conchae During inhalation

Filter, heat, and moisten incoming air

nasal conchae During exhalation

Moisture and heat are reclaimed

Paranasal sinuses are located within

Frontal bone
⚬ Maxillary bones
⚬ Sphenoid bone
⚬ Ethmoid bone

paranasal sinuses:

open into nasal cavity and help warm and moisten inhaled air

pharynx three sections

Nasopharynx
⚬ Oropharynx
⚬ Laryngopharynx

nasopharynx o

only an air passageway, closed off during swallowing. soft palate and uvula reflects superiorly (prevents food entering)

Pharyngeal tonsil (adenoids)

located on posterior nasophranygeal wall, lymphoid organ that destroys pathogens entering

Tubal tonsil

Provides the middle ear some protection against infections that may spread from the pharynx

fauces

Archlike entranceway directly behind the mouth

Palatine tonsils

in the lateral walls of the fauces

Lingual tonsils

cover the posterior surface of the tongue

Layngopharynx

passageway for Both food and air, stratified squamous epithelium

Larynx

voice box, opens into laryngopharynx.

larynx function

Voice production (creates vocalizations)
⚬ Provides an open airway
⚬ Routes air and food into the proper channels

Thyroid cartilage

Shield-shaped, forms laryngeal prominence (Adam’s apple)

Three pairs of small cartilages

Arytenoid cartilages - most important - anchor the vocal cords
⚬ Corniculate cartilages
⚬ Cuneiform cartilages

Vocal ligaments of the larynx

Within the larynx, paired vocal ligaments run anteriorly from the arytenoid cartilages to the thyroid cartilage

Vocal folds

true vocal cords, act in sound production

Vestibular folds (false vocal cords

no role in sound production

rimma glottidis

medial opening between the vocal folds through which air passes

Glottis

—rima glottidis and vocal folds together

Epithelium of the larynx

tratified squamous—superior portion
⚬ Pseudostratified ciliated columnar—inferior portion

larynx (voice production)

As the length and tension of the vocal folds change the pitch of the produced sound changes

laryngitis

infection from a bad cold stimulates inflammation of the larynx, causing vocal folds to swell and interferes with their ability to vibrate

hoarseness causes

overuse of voice, growth of vocal cord, inhalation of irritating chemicals (as in tobacco smoking)

trachea

windpipe

Trachealis

Contraction of the trachealis muscle decreases the diameter of the trachea

Carina

Marks where trachea divides into two primary bronchi
⚬ Pseudostratified ciliated columnar

Mucosa (trachea)

a mucous membrane, consists of an inner epithelium and a lamina propria

Submucosa (trachea)

another layer of connective tissue, contains glands with both serous and mucous cells

Adventitia

external layer of connective tissue

Fibromusculocartilaginous layer of the trachea

Cartilaginous rings

Bronchial tree:

a system of respiratory passages that branches
extensively within the lungs

Secondary (lobar) bronchi

Three on the right = superior, middle, and inferior

Tertiary (segmental) bronchi

Branch from lobar bronch

Bronchioles

Little bronchi, less than 1 mm in diameter

Terminal bronchioles (smallest bronchioles)

Less than 0.5 mm in diameter

Airways widens with

sympathetic stimulation
￭ Respiratory needs are great

Airways constricts under

parasympathetic direction
￭ Respiratory needs are low

Respiratory bronchioles

Lead to alveolar ducts

where do the alveolar ducts lead

alveolar sacs = straight ducts whose walls consist almost entirely of alveoli

Alveoli

400 million air-filled alveoli account for tremendous surface area for gas exchange

Type I alveolar cells

Single layer of simple squamous epithelial cells

Alveolar and capillary walls plus their basal lamina form

Respiratory membrane = where oxygen and carbon dioxide are exchanged between the alveolus and the blood

Type II alveolar cells

Secrete secrete a fluid that coats the internal alveolar surfaces

Surfactant

detergent-like substance
⚬ Reduces surface tension within alveoli

Alveolar pores

Allow air pressure to be equalized throughout the lung
￭ Provide alternative routes for air to reach alveoli

Alveolar macrophages

Live in the air space and remove the tiniest inhaled particles
that were not trapped by mucusLive in the air space and remove the tiniest inhaled particles
that were not trapped by mucus

Apex of lung

superior tip of lung, deep to the clavicle

base of lung

concave inferior surface rests on the diaphragm

Hilum of lung

indentation on mediastinal surface
￭ Is the region where blood vessels, bronchi, and nerves enter
and exit the lung

root of lung

the structures that enter and leave the lung at the hilum attach the lung of the mediastinum

Left lung

Is divided into two lobes = the superior lobe and the inferior lobe by the oblique fissue

right lung

is partionated into three lobes, superior, inferior and middle lobes by oblique and horizontal fissure

Bronchopulmonary segments

Each of the lobes contains a number of bronchopulmonary segments separated from one another by thin partitions of dense connective tissue

Each segment receives air from an

individual segmental bronchus Parasympathetic

Parasympathetic

bronchoconstriction and vasodilation

Sympathetic

bronchodilation and vasoconstriction

parietal pleura

covers the internal surface of the thoracic wall

visceral pleura

covers the external lung surface

plueral cavity

allows lung to glide without friction over the thoracic wall during breathing movement

Inspiration

inhalation
￭ The period when air flows into the lungs

Expiration—exhalation

The period when gases exit the lungs

what happens during inspiration

decreases internal gas pressure, diaphragm moves inferiorly, and intercostal muscles (contraction raises the ribs)

Deep inspiration requires

scalenes, sternocleidomastoid, quadratura lumborum, erector spinae

quiet expiration

passive process, diaphragm moves superiorly, volumes of thoracic cavity decreases

Forced expiration

an active process, produced by internal and external oblique muscles. transversus abdominis muscle

VRG—ventral respiratory group

Located in reticular formation in the medulla
oblongata

Bronchial asthma

A type of allergic inflammation

asthma attacks characterized by

contraction of bronchiole smooth muscle or secretion of muscus airways

cystic fibrosis

inherited disease, exocrine gland function is dirsupted over secretion of viscous mucus

by week 4 development

olfactory placodes (thickened plate of ectoderm) appear

Lower respiratory organs develop from a tubular
outpocketing off the pharyngeal foregut called the

laryngotracheal bud

When do the lungs reach functional maturity?

Late in development.

How does respiratory exchange occur during fetal life?

The lungs are filled with fluid, and all respiratory exchange occurs across the placenta.

How many alveoli are present at birth?

Only one-sixth of the alveoli are present at birth.

When do the lungs finish forming most of their alveoli?

Throughout childhood, with alveoli continuing to form until young adulthood.

aging of respiratory systems

numbers of glands in nasal mucosa declines