Chapter 22 Respiratory System

respiration

refers to ventilation of the lungs (breathing)

1) gas exchange: O2 and CO2 exchanged between blood and air 2) communication: speech and other vocalizations 3) olfaction: sense of smell 4) acid-base balance: influences pH of body fluids by eliminating CO2 5) Blood pressure regulation: by helping in synthesis of angiotensin II 6) Blood and lymph flow: breathing creates pressure gradients between thorax and abdomen that promote flow of lymph and blood 7) Blood filtration: lungs filter small clots 8) Expulsion of abdominal contents: breath-holding assists in urination, defecation, and childbirth (Valsalva maneuver)

what are the main functions of respiration?

nose, pharynx, larynx, trachea, bronchi, lungs

what are the principal organs of the respiratory system?

there are millions of thin-walled, microscopic air sacs and gases are exchanged with the bloodstream through the alveolar wall, and then flows back out

what happens when incoming air stops in the alveoli?

Conducting zone of respiratory system

this includes those passages that serve only for airflow; no gas exchange occurs here; it includes the nostrils through the major bronchioles

Respiratory zone of the respiratory system

this consists of alveoli and other gas exchange regions

Upper respiratory tract

this is in the head and neck and includes the nose through the larynx

Lower respiratory tract

this is the organs of the thorax and includes the trachea through the lungs

Warms, cleanses, and humidifies inhaled air; Detects odors; Serves as a resonating chamber that amplifies voice

what are the functions of the nose?

extends from nostrils (nares) to posterior nasal apertures (choanae) which are the posterior openings

where does nose extend from and to?

nasal fossae

right and left halves of the nasal cavity

nasal septum

what divides the nasal cavity?

Ethmoid and sphenoid bones form the roof; Hard palate forms floor which separates the nasal cavity from the oral cavity and allows you to breathe while you chew food

what forms the roof and floor of the nasal cavity?

Paranasal sinuses and nasolacrimal duct

what drains into the nasal cavity

vestibule

this is the beginning of the nasal cavity; small, dilated chamber just inside nostrils; it is lined with stratified squamous epithelium (resist frictional forces) and has vibrissae (guard hairs)

vibrissae

stiff guard hairs that block insects and debris from entering nose (in the vestibule)

into a larger chamber with not much open space

what does the nasal cavity expand into posteriorly?

nasal conchae

three folds of tissue that occupy the chamber behind the vestibule; includes superior, middle, and inferior

Project from lateral walls toward septum; a meatus is a narrow air passage beneath each concha; Narrowness and turbulence of conchae ensure that most air contacts mucous membranes; they clean, warm, and moisten the air

structure and function of nasal conchae

olfactory epithelium

this detects odor; it covers a small area of the roof of the nasal fossa and adjacent parts of the septum and superior concha; Immobile cilia on sensory cells bind odorant molecules

respiratory epithelium

lines the nasal cavity except the vestibule; has ciliated pseudostratified columnar epithelium with goblet cells and the cilia are motile; Goblet cells secrete mucus and cilia propel the mucus posteriorly toward pharynx; stuff is swallowed into digestive tract

erectile tissue (swell body)

extensive venous plexus in epithelium of inferior concha; Every 30 to 60 minutes, tissue on one side swells with blood; this restricts airflow through that fossa, so most air is directed through other nostril which allows engorged side time to recover from drying; Preponderant flow of air shifts between the right and left nostrils once or twice an hour

pharynx (throat)

muscular funnel extending about 5 in. from the choanae to the larynx

nasopharynx, oropharynx, laryngopharynx

what are the three regions of the pharynx?

nasopharynx

this receives auditory tubes and contains pharyngeal tonsil; the 90° downward turn traps large particles; this should only have air travel through it

oropharynx

Space between soft palate and epiglottis; Contains palatine tonsils; air, food, and drink can travel through it

laryngopharynx

Epiglottis to cricoid cartilage; Esophagus begins at that point

nasopharynx

what passes only air and is lined by pseudostratified columnar epithelium?

oropharynx and laryngopharynx

what passes air, food, and drink and are lined by stratified squamous epithelium

Muscles of the pharynx

what assists in swallowing and speech?

larynx (voice box)

cartilaginous chamber about 4 cm (1.5 in.) long; its primary function is to keep food and drink out of the airway, but it has an additional role of phonationp

phonation

production of sound

epiglottis

flap of tissue that guards the superior opening of the larynx

At rest, epiglottis stands almost vertically; During swallowing, extrinsic muscles of larynx pull larynx upward; Tongue pushes epiglottis down to meet larynx; which closes airway and directs food to esophagus behind it; Vestibular folds of the larynx play greater role in keeping food and drink out of the airway

structure and function of epiglottis(in the larynx)

nine

how many cartilages make up the framework of the larynx?

epiglottic, thyroid, and cricoid cartilage

what are three solitary and relatively large cartilages that make up the framework of the larynx?

epiglottic, thyroid, cricoid, arytenoid, corniculate, cuneiform

what are some of the cartilages that make up the framework of the larynx?

epiglottic cartilage

spoon-shaped supportive plate in epiglottis; most superior larynx cartilage; made primarily of elastic cartilage (flexible)

thyroid cartilage

largest larynx cartilage, laryngeal prominence (Adam’s apple); shield-shaped; Testosterone stimulates growth, larger in males

cricoid cartilage

connects larynx to trachea, ring-like (larynx cartilage)

arytenoid, corniculate, and cuneiform cartilages

what are the three smaller, paired cartilages of the larynx?

arytenoid cartilage

posterior to thyroid cartilage

corniculate cartilage

attached to arytenoid cartilages like a pair of little horns

cuneiform cartilage

support soft tissue between arytenoids and epiglottis

suspends larynx from hyoid and hold it together

what do ligaments in the larynx do?

thyrohyoid ligament

suspends larynx from the hyoid; more pronounced than the cricotracheal ligament

cricotracheal ligament

ligament that suspends the trachea from the larynx

superior vestibular folds

false vocal cords; Play no role in speech; Close the larynx during swallowing

vocal cords

Produce sound when air passes between them; Contain vocal ligaments; Covered with stratified squamous epithelium which makes them suited to endure vibration and contact

glottis

the vocal cords and the opening between them; it can change in diameter based on the tension put on the vocal cords

Usually longer and thicker; Vibrate more slowly; Produce lower-pitched sound

what are adult male vocal cords like compared to female cords?

loudness

what is determined by the force of air passing between the vocal cords?

actions of pharynx, oral cavity, tongue, and lips

what forms the words from the crude sounds produced by the vocal cords?

Higher tension results in higher pitch and lower tension in lower pitch

explain how tension and pitch relate?

trachea (windpipe)

a rigid tube about 12 cm (4.5 in.) long and 2.5 cm (1 in.) in diameter

anterior to esophagus; Supported by 16 to 20 C-shaped rings of hyaline cartilage that reinforce trachea and prevent collapse during inhalation; Opening in rings faces posteriorly toward esophagus; trachealis muscle spans the opening in rings: the gap in the C ring allows room for the esophagus to expand as swallowed food passes by and it also contracts or relaxes to adjust airflow

structure of trachea

inner lining of trachea is ciliated pseudostratified columnar epithelium and it is composed mainly of mucus-secreting cells, ciliated cells, and stem cells and it has a mucociliary escalator

explain inner lining of trachea

a mechanism for debris removal in the trachea; Mucus traps inhaled particles; Upward beating cilia drives mucus toward pharynx where it is swallowed

what is the mucociliary escalator?

it is connective tissue beneath the tracheal epithelium; Contains lymphatic nodules, mucous and serous glands, and the tracheal cartilages

explain the middle tracheal layer of the trachea

right and left main bronchi

what occurs when the trachea forks at level of the sternal angle?

carina

internal medial ridge in the lowermost tracheal cartilage that directs the airflow to the right and left lungs; has tactile receptors (light touch sensors)

tracheostomy

to make a temporary opening in the trachea and insert a tube to allow airflow

Prevents asphyxiation due to upper airway obstruction; air flow skips the larynx, pharynx, etc. and goes directly to trachea; Inhaled air bypasses the nasal cavity and is hot humidified; If left for long, will dry out mucous membranes of respiratory tract; then it would become encrusted and interfere with clearance of mucus from tract, thereby promoting infection

what does a tracheostomy do?

base

broad concave portion resting on diaphragm

apex

tip that projects just above the clavicle

costal surface

pressed against the ribcage

mediastinal surface

faces medially toward the heart

hilum

slit through which the lung receives the main bronchus, blood vessels, lymphatics, and nerves

they are crowded by adjacent organs; they don’t fill the entire ribcage; they are not symmetrical

a few characteristics of the lungs

Shorter than left because liver rises higher on the right; Has three lobes—superior, middle, and inferior—separated by horizontal and oblique fissure

characteristics of the right lung

Tall and narrow because the heart tilts toward the left and occupies more space on this side of mediastinum; has indentation (cardiac impression); Has two lobes—superior and inferior separated by a single oblique fissure

characteristics of the left lung

bronchial tree

a branching system of air tubes in each lung; goes from main bronchus to 65,000 terminal bronchioles

main (primary) bronchi

this bronchi is supported by C-shaped hyaline cartilage rings; it is the first branch point and sends air to the entire lung

lobar (secondary) bronchi

this bronchi is supported by crescent-shaped cartilage plates; there is one for each lobe of lung: right lung has 3, left lung has 2

segmental (tertiary) bronchi

this bronchi is supported by crescent-shaped cartilage plates; there are 10 on the right lung and 8 on the left lung; has the bronchopulmonary segment which is a functionally independent unit of the lung tissue

they are propped open with hyaline cartilage and has a mucociliary escalator inside

all bronchi are propped open with what that has what inside?

ciliated pseudostratified columnar epithelium;

what are all bronchi lined with?

line with ciliated pseudostratified columnar epithelium; the cells grow shorter and the epithelium gets thinner as we progress distally; All divisions of bronchial tree have a large amount of elastic connective tissue which contributes to the recoil that expel air from the lungs

common structure between all bronchi

1 mm or less in diameter; Have ciliated cuboidal epithelium; Well-developed layer of smooth muscle; Divides into 50 to 80 terminal bronchioles: these are the final branches of conducting zone, Have no mucous glands or goblet cells, Have cilia that move mucus draining into them back by mucociliary escalator, and each terminal bronchiole gives off two or more smaller respiratory bronchioles

what are characteristics of the bronchioles?

Have alveoli budding from their walls; Considered the beginning of the respiratory zone since alveoli participate in gas exchange; Divide into 2 to 10 alveolar ducts and end in alveolar sacs

characteristics of the respiratory bronchioles

alveolar sacs

clusters of alveoli arrayed around a central space called the atrium

it flows directly from one alveoli to the next door to the next via small perforations in each individual alveoli

how does air flow through alveolar ducts

squamous (type I) alveolar, great (type II) alveolar, alveolar macrophages (dust cells)

what are the types of cells of the alveolus?

thin, broad cells that allow for rapid gas exchange between alveolus and bloodstream; covers majority of alveolus surface area (95%); mucus is absent because it would inhibit rate of gas diffusion

structure and function of squamous (type I) alveolar cells

Round to cuboidal cells that cover the remaining 5% of alveolar surface; Repairs the alveolar epithelium when the squamous (type I) cells are damaged; Secretes pulmonary surfactant (amphipathic molecule that reduces the amount of hydrogen bonding - would help to reinflate alveoli if they were to deflate)

structure and function of great (type II) alveolar cells

Wander the lumens of alveoli and the connective tissue between them; Keep alveoli free from debris by phagocytizing dust particles; 100 million dust cells die each day as they ride up the mucociliary escalator to be swallowed and digested with their load of debris; they do not block surface diffusion

structure and function of alveolar macrophages (dust cells)

Each alveolus is surrounded by a basket of capillaries which is supplied by the pulmonary artery

what is each alveolus surrounded and supplied by?

respiratory membrane

thin barrier between the alveolar air and blood

squamous alveolar cells; Endothelial cells of blood capillary; Their shared basement membrane; gas exchange between gases of alveoli and gases of blood stream occur here; it is the thinnest possible membrane that still has separation of fluid

what does the respiratory membrane consist of?

lower

does blood in the lungs have a lower or higher concentration of oxygen compared to the air in the alveoli?

fluid

what is important to prevent accumulating in the alveoli?

Gases diffuse too slowly through liquid to sufficiently aerate the blood; Alveoli are kept dry by absorption of excess liquid by blood capillaries; Lungs have a more extensive lymphatic drainage than any other organ in the body; low capillary blood pressure also prevents rupture of the delicate respiratory membrane

why is it important to prevent fluid from accumulating in the alveoli and how is it done?

visceral pleura

serous membrane that covers lungs (it is against the lungs)

parietal pleura

adheres to mediastinum, inner surface of the rib cage, and superior surface of the diaphragm (it is against the wall)

pleural cavity

potential space between pleura; there is normally no room between the membranes, but it contains a film of slippery pleural fluid

reduce friction; creates pressure gradient (Lower pressure than atmospheric pressure which assists lung inflation); compartmentalization (Prevents spread of infection from one organ in mediastinum to others)

functions of the pleura and pleural fluid

breathing (pulmonary ventilation)

consists of a repetitive cycle of inspiration (inhaling) and expiration (exhaling)

respiratory cycle

one complete inspiration and expiration

quiet respiration

respiration while at rest; effortless and automatic

forced respiration

respiration that is deep, rapid breathing, such as during exercise