introduction and respiratory anatomy

lecture 1

upper respiratory system

nose, mouth, pharynx, and larynx

lower respiratory system (tracheobronchial tree)

extrathoracic trachea and intrathoracic tracheobronchial tree

conducting pathway

air movement through tubular organs, with no exchange of gases with blood

conducting pathway movement (nose → terminal bronchioles)

nose → pharynx (nasopharynx, oropharynx, laryngopharynx) → trachea → bronchi → bronchioles → terminal bronchioles

acinus (respiratory zone)

respiratory bronchioles, alverolar ducts, alveoli

nose structure

2 asymmetrical nasal fossae, beginning with nostril, separated by septum

nose functions

olfaction, air conditioning, cleaning of air

air conditioning: warming and humidification

• warming: capillary network in nasal epithelium

• humidification: nasal goblet cells

cleaning of air: large and small particles

• large particles (10 um): removed by nasal hairs

• smaller (1 um): removed by inspiration

external nose

anterior portion, opens inferiorly to atmosphere

nasal vestibule

• lined with epithelium similar to skin (stratified squamous, kertinized)

• nostrils separated by cartilaginois and bony septum

• contains vibrissae to prevent large particle entry

• redirects air from different orientations for laminar flow

• thermoreceptors

nasal psuedovalves

narrowed opening within the nose; internal and external

external nasal psuedovalves

where nostrils open to the outside

internal nasal pseudovalves

• usually narrowest nasal segment

• upper and lower lat cart, septum, nose floor, head

• transition between skin and respiratory epithelium

• erectile tissue of nasal septum and inferior nsal conchae

internal nose

• hard & soft palate floor, cribriform plate ceiling, sphenoid posteriorly

• contains the septum, lateral wall, turbinates, and meatus

septum

superiorly by perpendicular plate (ethmoid), posteroinferiorly by vomer

lateral wall

three curved bones: superior, middle, inferior conchae

turbinates

outgrowth on conchae;

• increase SA for trasnfer of heat and moisture

• goblet cells secrete mucus to stop particles

• ciliated cells have 25-100 cilia; beat from front to nasopharynx

• highly vascular lamina propria

meatus

space below turbines

• superior, middle, inferior

• middle: semilunar hiatus opening to maxillary, frontal, and anterior ethmoid

• inferior: nasolacrimal duct drainage

epithelium of the nasal cavity

• transition from keratinized stratified squamous in nostril to pseudostratified ciliated columnar

• goblet cells throughout

• superior portion contains olfactory epithelium

mucus

• protective barrier covering mucosal surfaces

• maintains airway hydration

• traps and removes foreign particles

• antioxidant, antiprotease, antimicrobial

• hypersecretion connects mucus strands with goblet cells

2 layers of mucus blanket

• outer layer: gel

• perciliary layer: ion transport through epithelium; ciliary beating

nasal cycle

• nasal turbinates congest and decongest alternately

• duration 30 min - 6 hrs

• nasal resistance and respiratory work constant

submucosal venous sinuses plexus

• airflow regulated by erectile venous tissue of nasal mucosa

• anterior nasal septum and inferior turbinate most developed sinuses

• sinus cushions expand and shrink based on congestion

decongested side

working phase

• air through

• warm, moisturized, cleaned

congested side

resting phase

• mucosa stores heat and moisture for working phase

nasal cycle functions

• pumping mechanism for plasma exudate: water in mucus for humidification

• defense: plasma with immunoglobulins and inflammatory mediators

• entraps pollutants due to low velocity and hydration of congested side

nasal cycle patterns

classic, parallel, irregular, no pattern

nasal cycle classic pattern

reciprocal alteration and constant volume

nasal cycle parallel pattern

congestion or decongestion both sides simultaneously

nasal cycle irregular pattern

mutual alteration of volume without defined pattern; same volume

nasal cycle no pattern

total volume and nasal volume do not differ

what controls the nasal cycle?

sympathetic autonomic NS

physiology of nasal cycle (sleep and posture)

• sleep: majority of time spontaneous alterations occur in REM stage

• posture: sitting supine increases central venous pressure, leading to congestion

  • changes in nasal vasomotor tone in lateral lying position increases congestion on same side

  • positional changes can reverse congestion

paranasal sinuses

• air-filled cavities within specific bones of cranium

• maxillary sinuses, multiple ethmoid sinuses, frontal sinus, sphenoid sinus

• contain ciliated epithelium, secrete mucus, participate in mucociliary clearance

maxillary sinuses

drain into middle meatus

multiple ethmoid sinuses

• anterior cells communicate with middle meatus (3-7 cells)

• posterior cells communicate with superior meatus (2-4 cells, larger)

frontal sinus

two sinuses, separated by bony septum, drain into middle meatus

sphenoid sinus

drains to sphenoethmoid recess (between superior turbinate septum, and sphenoid front wall)

pharynx

• posterior wall against cervical vertebrae

• eustachian tubes open into lateral wall

• 3 regions: naso-, oro-, and laryngo-

nasopharynx

posterior nose to soft palate

oropharynx

behind oral cavity; posterior and lateral walls of superior and middle pharyngeal constrictors

laryngopharynx

posterior and lateral walls of middle and inferior pharyngeal constrictors

larynx

• vocal organ

• separates air and food by swallowing reflex

• 3 regions: supraglottis, glottis, and subglottis

supraglottis

epiglottis, arepoglottic folds, false vocal folds, ventricle

glottis

true vocal folds

subglottis

leads to tracea

chest wall thoracic bones

ribs, sternum, thoracic vertebrae

ribs

• true ribs 1-7 with own costal cartilage

• false ribs 8-10 share costal cartilage

• floating ribs 11-12, no costal cartilage

sternum

• manubrium 1st and 2nd costal cartilage

• sternal body 3rd-7th costal cartilage

• xiphoid process

thoracic vertebrae

T1-T12; costovertebral joint between ribs and TP of vertebrae

thoracic muscles

diaphragm, external intercostals, internal intercostals, innermost intercostals

diaphragm

• primary inspiration muscle

• separates thoracic from abdominal cavities

• inserts lower ribs, posterior xiphoid, bodies of lumbar vertebrae

• upper surface covered by pleura and pericardium

external intercostals

• oriented obliquely downward and inward from inferior to superior rib

• elevate rib cage, increase lateral, interior, and posterior thorax dimensions

internal intercostals

• oriented diagonally donward and outward

• pull ribs down and inward, decreasing thoracic volume

innermost intercostals

form deepest layer, with transversus thoracis and subcostal

mediastinum

• space located in the chest

• bordered by: sternum (anteriorly), spinal column (posteriorly), lungs (laterally)

mediastinum contains what organs

heart, thymus, main bronchi, esophagus, thoracic duct, nerves, lymph vessels, and nodes

mediastinum divisions

superior, anterior, middle, posterior

trachea and main bronchi

• tube 12-14cm length, 13-22mm width, 3-6mm sagittal

• support from 16-20 U-shaped cartilage rings

  • incorporated in a connective tissue w/ elastin and collagen fiber

  • reinforcement, but flexible

  • collapses with forced expiration and cough, widens with deep inspiration

• connective tissue and smooth muscle posteriorly

• divides at carina to L and R main bronchi

  • Rt bronchus shorter

  • Lt bronchus branches at sharper angle

epithelium of trachea

• ciliated cells, goblet cells, brush cells, basal cells, kulchitsky cells

• tight junctions prevent penetration of inhaled particles to deeper layers

ciliated cells

rows of hundred cilia at apical surface

goblet cells

single or groups between ciliated cells; secrete mucus stored in cytoplasmic vacuoles

brush cells

apical microvilli, sometimes few cilia; possibly sensors or precursors to ciliated cells

kulchitsky cells

• believed to be neuroendocrine; possibly sense gases during inspiration & have a role ventilation/perfusion

• may become neoplastic due to response to airway irritation

wall of trachea

lamina propria, submucosal layer, fibrosa, connective tissue between tracheal rings

lamina propria

collagen fibers and elastin bundles

• nervous and vascular networks

• glandular ducts travel through layer

submucosal layer

bronchial mucus glands (main source of secret); bronchial smooth muscle

fibrosa

external hyaline cartilage layer

connective tissue

tracheal rings; nerves, blood vessels, lymph nodes