Unit IV- Respiratory System

Question 1

Respiratory System Components

Answer 1

• conduits for air passage
• muscle and CT for movement of gases
• gas exchange tissues

Question 2

Respiratory system functions

Answer 2

• conduction of air
• conditioning of air
• gas exchange
• host defense

Question 3

Inspiration

Answer 3

• active at rest through contraction of external intercostals (between ribs) and diaphragm
• the pressure is directed out, gets negative

Question 4

Expiration

Answer 4

• passive at rest through the elastic recoil properties of the connective tissue in lungs and chest wall
• pressure directed in, gets positive

Question 5

Air conditioning

Answer 5

• 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 6

Gas exchange

Answer 6

• highly specialized epithelial
• maximize surface area
• minimize diffusion distance

Question 7

Respiratory Epithelial

Answer 7

• conducting portion: pseudostratified columnar with cilia
• gas exchange- simple squamous
• changes gradually from one type to the other

Question 8

Cell types of respiratory epithelial

Answer 8

• cilated pseudostratified columnar cells- most abundant, 250 cilia on apical surface, have basal bodies
• mucous goblet cells
• brush cells- sensory receptors, extend from basement to lumen, have microvilli
• basal cells (regenerative0- on basement membrane but are short and rounded
• granule cells- neuroendocrine, fail to reach lumen but do sit on basement membrane

Question 9

Mucociliary elevator

Answer 9

• coordinated beating of cilia toward exit
• particles trapped in mucous floating on aqueous layer
• cilia deeper into respiratory tract than goblet cells to prevent retrograde flow

Question 10

Kartagener syndrome

Answer 10

• dynein dysfunction
• no ciliary beating
• respiratory infections

Question 11

Conducting portion

Answer 11

• nasal cavity
• larynx
• trachea
• bronchi
• bronchioles; regular and terminal

Question 12

Nasal cavity (vestibule)

Answer 12

• transition from keratinized to respiratory epithelium
• sebaceous and sweat glands
• Vibrissae for filtration (nose hairs)

Question 13

Nasal Cavity (Fossae)

Answer 13

• chambers in skull separated by septum
• 3 conchae- bone covered with CT and epithelium (inferior, middle, superior); venous plexus in CT to warm air (swell bodies)
• 3 meati- spaces between conchae; inferior and middle lined with respiratory epithelium, and superior is lined with olfactory epithelium

Question 14

Countercurrent Exhange

Answer 14

-in the conchae and meati, the air gains heat that is given off by the blood in the venous plexus

Question 15

Olfactory epithelium

Answer 15

• 10 sq cm of superior conchae
• supporting cells- apical microvilli, apical nuclei
• olfactory cells- bipolar neurons, basal nuclei
• basal cells- regenerative, basal
• Olfactory (Bowman’s) glands- produce serous secretions to clear cilia and facilitate access of new odorants, found a little bit before olfactory epithelium

Question 16

Paranasal Sinus

Answer 16

• chambers in bones of skull lined with respiratory epithelium
• connected to nasal cavity via small passages
• chambers in frontal, maxillary, ethmoid, sphenoid bones

Question 17

Larynx

Answer 17

• connects pharynx and trachea
• epiglottis prevents food entering trachea
• vocal cords permit phonation
• vestibular fold- false
• true vocal cord

Question 18

Vestibular fold

Answer 18

• false vocal cord
• respiratory epithelium
• serous glands in lamina propria
• lie superior to vocal cords
• no dense ligaments
• no skeletal muscle

Question 19

Vocal cords

Answer 19

• phonation
• vocal ligament (fibroelastic0
• vocalis muscle (skeletal)
• stratified squamous epithelium- abrasion resistance

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 (1/2 cm apart) 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 cilated simple columnar/cuboidal
• increase in smooth muscle for ventilation
• few goblet cells or glands
• Clara cells take over secretory function
• regular: mostly columnar with folded intima because of smooth muscle
• 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

• 300 million alveoli
• 150 sq meters of gas exchange surface
• highly specialized epithelium
• diffusion path for gas (IN)
• surfactant
• epithelium (two membranes and cytoplasm)
• epithelial basal lamina
• endothelial basal lamina- fused as one basement membrane
• endothelium (two membranes and cytoplasm)
• red blood cell membrane

Question 28

Alveolar Cells

Answer 28

• Type II- surfactant source, regenerative, found at septal junctions
• Type I- 8% by number, 97% by surface area
• endothelial 30%- very thin, crescent shaped nuclei
• alveolar macrophages 10%- dust cells, found from capillary to outer epithelium, bone marrow
• RBC
• fibroblasts, mast cells
• Type I-

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 interstitium

Answer 30

• type III collagen, elastic fibers, proteoglycans

- critical for pulmonary mechanics

Question 31

Pores of Kohn

Answer 31

• equalize air pressure between alveoli

- promotes collateral air circulation

Question 32

Pulmonary Circulation

Answer 32

• Nutrient (systemic)- brings oxygen and nutrients to lung tissue
• found in submucosa
• functional (pulmonary)- blood from pulmonary artery to be oxygenation
• thin walled, low pressure
• follows bronchial tree
• branches to capillaries at sites of gas exchange

Question 33

Pulmonary Host Defense

Answer 33

• Acid-Base Balance: regulate CO2, short term pH regulator
• Metabolic: pulmonary capillary endothelium- inactivate bradykinin, serotonin, acetylcholine, etc
• convert angiotension I to angiontensin II
• Immunologic- cellular- vibrissae, muco-cilary 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 34

Pleura

Answer 34

• serous membrane which encapsulates entire lung
• fusion of parietal and visceral layers at hilus
• mesothelial layer

Question 35

Innervation

Answer 35

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