"Microscopic Anatomy Respiratory System Scott Blystone" GABY

Question 1

Respiratory System Functions

Answer 1

• Conduction of air
• Conditioning of air
• Gas exchange
• Host defense

Question 2

Inspiration

Answer 2

Active at rest through contraction of external intercostals and diaphragm

Question 3

Expiration

Answer 3

Passive at rest through the elastic recoil properties of the connective tissue in the lungs and chest wall

Question 4

Air Conditioning

Answer 4

• Inspired air is filtered to prevent entry of pathogens or irritants
• Inspired air is warmed and humidified to promote gas exchange and to prevent tissue damage due to cold air or desiccation

Question 5

Gas Exchange

Answer 5

• Highly specialized epithelia
– Maximize surface area
– Minimize diffusion distance

Question 6

Respiratory Epithelia

Answer 6

• Conducting Portion
– pseudostratified columnar with cilia

• Respiratory Portion (Gas Exchange)
– simple squamous

Question 7

Respiratory Epithelia

Answer 7

• *Ciliated pseudostratified columnar cells
• *Mucous goblet cells
• *Brush cells (sensory receptors)
• Basal cells (regenerative)
• Granule cells (neuroendocrine)

*extend to apical lumen

Question 8

Mucociliary elevator

Answer 8

• Coordinatedbeatingof cilia toward exit
• Particlestrappedin mucous floating on aqueous layer
• Cilia deeper into respiratory tract than goblet cells to prevent retrograde flow

Question 9

Kartagener syndrome

Answer 9

• dynein dysfunction
• no ciliary beating
• respiratory infections

Question 10

Conducting Portion

Answer 10

• Nasal Cavity 
• Larynx
• Trachea
• Bronchi
• Bronchioles 
– Regular
– Terminal

Question 11

Nasal Cavity (Vestibule)

Answer 11

– transition from keratinized to respiratory epithelium
– Sebaceous and sweat glands
– Vibrissae for filtration

Question 12

Fossae of Nasal Cavity

Answer 12

• Chambers in skull separated by septum
– 3 Conchae, bony projections covered with epithelium
– 3 Meati, spaces between conchae

Question 13

Nasal Meati and Conchae

Answer 13

• Dense venous plexus 
– warmth & humidity
• Inferior&Middle
– ciliated pseudostratified columnar epithlium
• Superior
– olfactory epithelium

Question 14

Olfactory epithelium

Answer 14

• 10 sq. cm. Of superior conchae
• Supportingcells
– microvilli NOT cilia 
– apical nuclei
• Olfactorycells
– bipolar neurons, basal nuclei
• Basalcells
– regenerative, basal

Question 15

Paranasal Sinus

Answer 15

• Chambers in bones of skull lined with respiratory epithelium
• Connected to nasal cavity via small passages

Question 16

Larynx

Answer 16

• Connects pharynx and trachea
• Epiglottis prevents food entering trachea
• Vocal cords permit phonation
– Vestibular fold 
– True vocal cord

Question 17

Vestibular Fold (false vocal cord)

Answer 17

• Respiratory Epithelium
• Serous glands in lamina propria
• Lie superior to vocal cords
• No dense ligaments
• No skeletal muscle

Question 18

Vocal Cords

Answer 18

• Phonation
– vocal ligament (fibroelastic)
– vocalis muscle (skeletal)
• Stratified squamous epithelium
– abrasion resistance

Question 19

Laryngeal cartilage

Answer 19

• Thyroid
• Cricoid
• Subject to ossification

Question 20

Trachea

Answer 20

• 10 cm tube connecting larynx and bronchi
• ciliated pseudostratified columnar epithelium
• Goblet cells, mixed serous and mucous glands
• Limited elastic fibers
• 16-20 incomplete rings of hyaline cartilage connected dorsally by smooth muscle and fibroelastic ligament

Question 21

Bronchi

Answer 21

• One primary bronchi per side
• 3 lobar bronchi in right lung, 2 in left lung
• Branches of lobar bronchi are small bronchi
• Histologically similar to trachea, however:
• Cartilage is in irregular plates
• Smooth muscle in irregular bands
– postmortem constriction induces folds

Question 22

Conducting Bronchioles

Answer 22

• Regular and Terminal
• NO cartilage
• Epithelial transition to ciliated simple columnar/cuboidal
• Increase in smooth muscle for ventilation control
• Few goblet cells or glands
• Clara cells take over secretory function
• Regular:
– mostly columnar with folded intima
• Terminal:
– cuboidal with no folding

Question 23

Respiratory Portion

Answer 23

• Bronchioles 
– Respiratory
• Alveolar 
– Ducts
– Sacs
– Alveoli

Question 24

Respiratory Bronchiole

Answer 24

• Histologically identical to terminal bronchiole
– some cilia remain on cuboidal epithelium
• Outpockets of alveoli in bronchiolar walls permits gas exchange

Question 25

Alveolar Ducts and Sacs

Answer 25

* Air passage completely lined with alveolar openings * Simple squamous epithelium * NO cilia or clara cells * Alveolar Sacs are common space share by multiple alveolar openings

Question 26

Alveolar Cusps

Answer 26

• At common alveolar openings (sacs, ducts), there are knoblike projects containing innervated smooth muscle for regulation of pulmonary ventilation

Question 27

Alveolar septum

Answer 27

``` • Diffusion path for gas (IN) – surfactant – epithelium • (two membranes + cytoplasm) – epithelial basal lamina – endothelial basal lamina • fused as one basement membrane – endothelium • (two membranes + cytoplasm) – red blood cell membrane ```

Question 28

Alveolar Cells

Answer 28

``` • Type II – surfactant source – regenerative • Type I – 8% by number, 97% by surface area • Endothelial • Dust • RBC • Fibroblasts, Mast cells ```

Question 29

Alveolar macrophage

Answer 29

* Dust cells * Found from capillary to alveolar space * Bone marrow origin, differentiate on site * Critical to host defense against inspired pathogens or irritants

Question 30

Acellular alveolar features

Answer 30

``` • Acellular interstitium – type III collagen, elastic fibers, proteoglycans – critical for pulmonary mechanics • Pores of Kohn – equalize air pressure between alveoli – promotes collateral air circulation ```

Question 31

Pulmonary Circulation

Answer 31

• Nutrient (systemic) – Brings oxygen and nutrients to lung tissue – Found in submucosa • Functional (pulmonary) – Blood from pulmonary artery to be oxygenated – thin walled, low pressure – follows bronchial tree – branches to capillaries at sites of gas exchange

Question 32

Pulmonary Host Defense

Answer 32

• Acid-Base Balance – Regulate CO2 , short term pH regulator • Metabolic – Pulmonary capillary endothelium • Inactivate bradykinin, serotonin, acetylcholine, etc • Convert angiotensin I to angiotensin II • Immunologic – Cellular • vibrissae, muco-ciliary elevator, alveolar macrophages – Humoral • BALT (Bronchus-Associated Lymphoid Tissue) • Immunoglobulins A and E • Monitor for specific antigens in the respiratory tree – Mast cells reactive to allergens

Question 33

Pleura

Answer 33

– serous membrane which encapsulates entire lung – fusion of parietal and visceral layers at hills – mesothelial layer

Question 34

Innervation

Answer 34

– both sympathetic and parasympathetic innervation – regulation of bronchial dilation (ventilation) – poorly localized pain responses