A&P II Respiratory system

respiratory system

organ system that takes in air and expels if from the body

respiration

ventilation of the lungs (breathing)

gas exchange, communication, olfaction, acid-base balance, blood pressure regulation, blood and lymph flow, platelet production, blood filtration, and expulsion of abdominal contents

functions of the respiratory system

gas exchange

oxygen and carbon dioxide exchanged between blood and air

communication

speech and other vocalizations

olfaction

sense of smell

acid-base balance

influences pH of body fluids by eliminating carbon dioxide

blood pressure regulation

assists with synthesis of angiotensin II, a hormone that regulates blood pressure

blood and lymph flow

breathing creates pressure gradients between thorax and abdomen that promote flow of lymph and blood

platelet production

more than half of platelets are made by megakaryocytes in lungs

blood filtration

lungs filter small clots

expulsion of abdominal contents

breath-holding assists in urination, defecation, and childbirth

nose, pharynx, larynx, trachea, bronchi, and lungs

priciple organs of the respiratory system

conducting zone

passages that serve only for airflow (no gas exchange)

respiratory zone

regions that participate in gas exchange

upper respiratory tract

airway from nose through larynx (nose, pharynx, and larynx)

lower respiratory tract

regions from trachea through lungs (trachea, bronchi, lungs)

nose

warms, cleanses, and humidifies inhaled air; detects odors; and serves as a resonating chamber that amplifies voice

nasal bones and maxillae

superior half of nose

hyaline cartilage

inferior half of nose

nasal septum

divides nasal cavity into right and left nasal fossae

vestibule

small, dilated chamber just inside nostrils, lined with stratified squamous epithelium

guard hairs or vibrissae

stiff hairs that block insects and debris from entering nose

goblet cells

produce most of the mucus, supplemented by mucous glands in lamina propria

ciliated cells

have motile cilia that propel that mucus posteriorly toward pharyx to be swallowed

olafactory glands

secrete serous fluid to assist diffusion of odor molecules to receptors on the cilia

pharynx

muscular funnel extending about 13cm from posterior nasal apertures to larynx, divided into 3 regions

nasopharynx

posterior to nasal apertures and above soft palate; receives auditory tubes and contains pharyngeal tonsil; 90 degree downward turn traps large particles; passes only air and is lined by pseudostratified columnar epithelium

oropharynx

space between soft palate and epiglottis; contains palatine tonsils; passes air, food, and drink, and is lined by stratified squamous epithelium

laryngopharynx

posterior to larynx, from epiglottis to cricoid cartilage; espohagus begins at that point; passes air, food, and drink, and is lined by stratified squamous epithelium

larynx

cartilaginous chamber about 4cm long; primary function is to keep food and drink out of airway; also involved in production of sound, so commonly called the “voice box”

epiglottis

flap of tissue that guards superior opening of larynx; at rest, it stands almost vertically; during swallowing extrinsic muscles pull larynx upward; tongue pushes epiglottis down to meet it; 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

epiglottic cartilage

most superior; spoon-shaped supportive plate in epiglottis

thyroid cartilage

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

cricoid cartilage

ring-like shape; connects larynx to trachea

vestibular folds

play no role in speech, but close the larnyx during swallowing; supported by the vestibular ligaments

vocal cords (vocal folds)

produce sound when air passes between them; contians vocal ligaments covered with stratified squamous epithelium, suited to endure vibration and contraction

glottis

the vocal cords and the opening between them

trachea

tube that connects larynx to bronchi; commonly called the “windpipe”; rigid tube 12cm long and 2.5cm in diameter; anterior to esophagus; supported by 16 to 20 C-shaped rings of hyaline cartilage- prevent collapse during inhalation; opening in cartilage rings faces posteriorly toward esophagus; allows esophagus to expand as swallowed food passes by

trachealis

muscle spans opening in rings; contracts or relaxes to adjust airflow

carina

lowermost tracheal cartilage has internal medina ridge

mucociliary escalator

mechanism for debris removal; mucus traps inhaled particles, upward beating cilia moves mucus to parynx to be swallowed

mucosa

lined by ciliated pseudostratified columnar epithelium; contains mucus-secreting cells, ciliated cells, and stem cells

submucosa

connective tissue beneath the tracheal epithelium contains lymphoid nodules, mucous and serous glands, and the tracheal cartilages

adventitia

outermost layer of trachea; fibrous connective tissue that blends into adventitia of other, nearby organs (esophagus)

tracheotomy

to make a temporary opening in the trachea and insert a tube to allow airflow; prevents asphyxiation due to upper airway obstruction

intubation

when a patient is on a ventilator, air is introduced directly into trachea; air must be filtered and humidified

base of lung

broad concave portion resting on diaphragm

apex of lungs

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 branches, blood vessels, lymphatics, and nerves

right lung

shorter than left because liver rises higher on the right; has 3 lobes- superior, middle, and inferior lobes; horizontal fissure separates superior and middle lobes, and oblique fissure separates middle and inferior lobes

left lung

tall and narrow because the heart tilts toward the left and occupies more space on this side of mediastinum; has indentation to accomodate heart- cardiac notch; has 2 lobes- superior and inferior lobes, separated by a single oblique fissure

bronchial tree

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

main (primary) bronchi

arise from fork of trachea; right main bronchus is wider and more vertical than left main bronchus

lobar (secondary) bronchi

a lobar bronchus serves each lobe of the lung; right main bronchus gives off 3 branches: superior, middle, inferior lobar bronchi; left main bronchus gives off 2 branches: superior and inferior lobar bronchi

bronchopulmonary segment

functionally independent unit of lung ventilated by a segmental bronchus

bronchioles

continuations of the airway that lack supportive carilage and are 1mm or less in diameter

pulmonary lobule

portion of lung ventilated by one bronchiole

alveolar sacs

clusters of alveoli around a central space

alveoli

microscopic air pouches in the lungs, each about 0.2 to 0.5 mm in. diameter

squamous (type 1) alveolar cells

thin cells allow rapid gas diffusion between air and blood; cover 95% of alveolar surface area

great (type 2) alveolar cells

round to cuboidal cells that cover the remaining 5% of alveolar surface; repair the alveolar epithelium when the squamous (type 1) cells are damaged; secrete pulmonary surfactant

pulmonary surfactant

mixture of phospholipids and proteins that coats the alveoli and prevents them from collapsing during exhalation

alveolar macrophages (dust cells)

most numerous of all cells in the lungs; wander lumens of alveoli and connective tissue between them; keep alveoli free from debris by phagocytizing dust particles; millions of dust cells die each day as they ride up the mucociliary escalator to be swallowed and digested witht their load of debris

respiratory membrane

thin barrier between the alveolar air and blood

pulmoary circiut

serves to unload carbon dioxide from blood so it can be exhaled, and pick up oxygen from inhaled air

bronchial arteries

arise from aorta, supply lung tissue with blood supply

bronchial veins

drains the blood into aztgos vein of thorax

right-to-left shunt

some bronchial venous blood mixes with pulmonary venous blood, diluting the oxygen content somewhat

pleura

serous membrane that lines thoracic wall and forms surface of lung

visceral pleura

forms surface of the lung

parietal pleura

adheres to mediastinum, inner surface of the rib cage, and superior surface of the diaphragm

pleural cavity

potential space between pleurae

pleural effusion

pathological seepage of fluid into the pleural cavity

reduaction of friction, creation of pressure gradient (assists with lung inflation), and compartmentalization (prevents spread of infection throughout organs)

functions of the pleurae and pleural fluid

diaphragm

prime mover of respiration

internal and external intercostal muscles

assist diaphragm

normal quiet respiration

energy-saving passive process achieved by the elasticity of the lungs and thoracic cage

valsalva maneuver

breathing technique used to help expel contents of certain abdominal organs

ventral respiratory group (VRG)

in medulla; primary generator of the respiratory rhythm

dorsal respiratory group (DRG)

in medulla; modifies the rate and depth of breathing

pontine respiratory group (PRG)

in pons; modifies rhythm of ventral respiratory group by outputs to both VRG and DRG; adapts breathing to special circumstances such as sleep, exercise, vocalization, and emotional responses

central chemoreceptors

brainstem neurons that respond to changes in pH of cerebrospinal fluid

peripheral chemoreceptors

cartoid and aortic bodies; respond to the oxygen and carbon dioxide and the pH of blood

stretch receptors

in smooth muscle of bronchi and bronchioles, and in the visceral pleura; respond to inflation of the lungs

inflation (Hering-Breuer) reflex

triggered by excessive inflation; protective reflex that inhibits inspiratory neurons and stops inspiration

irritant receptors

nerves endings amid the epithelial cells of the airway; respond to smoke, dust, pollen, chemical fumes, cold air, and excess mucus; trigger protective reflexes such as bronchoconstriction, shallower breathing, breath-holding (apnea), or coughing

breaking point

when carbon dioxide levels rise to a point where automatic controls override one’s voluntary will when holding breath

atmosperic (barometric) pressure

the weight of the air above us

intrapulmonary pressure

air pressure within lungs

boyle’s law

at a constant temperature, the pressure of a given quantity of gas in inversely proportional to its volume

intrapleural pressure

the slightly negative pressure that exists between the 2 pleural layers

charle’s law

the volume of a gas is directly proportional to its absolute temperature

bronchodilation

increase in diameter of bronchus or bronchiole; increases airflow

bronchoconstriction

decreases in diameter of bronchus or bronchiole; decrease airflow

pulmonary compliance

ease with which the lungs can expand; change in lung volume relative to a given pressure change

infant respiratory distress syndrome (IRDS)

premature babies lacking surfactant are treated with artificial surfactant until they can make their own

physiological (total) dead space

sum of anatomical dead space and any pathological dead space