Respiratory System

Question 1

Functions

Answer 1

Gas exchange
body temperature control
phonation
olfaction
metabolic function

Question 2

Functional adaptations

Answer 2

gas exchange
moistening of air
warming of air
filtering of air
phonation

Question 3

Major subdivisions

Answer 3

conduction portion
transitional portion
respiratory/exchange portion

Question 4

Respiratory epithelia

Answer 4

pseudostratified columnar - with goblet cells and basal cells; found from nasal fossa to the small bronchi (number of goblet cells decreases near the small bronchi)

ciliated simple columnar or cuboidal epithelium - lines bronchioles, contains very few/no goblet cells

simple squamous epithelium - lines alveoli of lungs

Question 5

Functional morphology/general organization

Answer 5

Lumen = airway
Mucosa: epithelium on thick basal lamina - lines lumen - PSC with goblet cells
Lamina propria/submucosa - rich in vascular CT with glands in places
Tunica muscularis - muscle and/or cartilage (provides support)
Tunica adventitia - CT when present

Question 6

Nasal cavity - divisions

Answer 6

vestibule
conducting region
olfactory region

Question 7

Paranasal sinuses

Answer 7

bounded by maxillary, frontal, ethmoid, and sphenoid bones
continous with nasal cavity
lined by a thin PSC epithelium w/a few goblet cells
mucosa lacks erectile tissue
mucosa is tightly adhered to underlying bone (=mucoperiosteum)

Question 8

Vomeronasal organ

Answer 8

=Jacobsen’s organ
pair of fluid-filled tubes connected via ducts to the nasopalatine canal (runs from incisive papilla in oral cavity to nasal cavity
lined by respiratory epith
have olfactory epith in their medial walls

function: permits sampling of substances that are volatilized by licking or inhalation
sex-scent-capturing ability
scenting apparatus transmits info directly to limbic system (sets mating behavior)

Question 9

Nasopharynx

Answer 9

nasal passage dorsal to soft palate
connects nasal cavity w/laryngopharynx
lines by PSC ciliated epithelium with goblet cells
contains pharyngeal tonsil = unencapsulated lymphoid tissue on pharyngeal septum (deep to PSC epith and in lamina propria)

Question 10

Larynx

Answer 10

cartilage supported muscular tube
connects pharynx w/trachea
solely respiratory structure
several functions, including phonation
branched tubuloacinar glands
diffuse and nodular lymphoid tissue present
sensory innervation via 9th and motor via 10th CNs for gagging and coughing reflexes

Question 11

Trachea - tunica submucosa

Answer 11

Epithelium - PSC ciliated w/goblet cells on thick basement membrane
Lamina propria - loose CT
Muscularis mucosae - longitudinally oriented elastic fibers
Submucosa: loose to coarse CT & simple tubuloalveolar mucous glands

Question 12

Trachea - tunica muscularis

Answer 12

Reduced in thickness relative to larynx
supportive CT - C shaped hyaline cartilage rings
smooth tracheal muscle oriented transversely and attached to inner tracheal cartilages in all domestic spp except carnivores (attach on outside)
Sm. ms. can narrow lumen - important in cough reflex

Question 13

Trachea - tunica adventitia

Answer 13

Loose to coarse CT

Question 14

Bronchi

Answer 14

divides left and right bronchi further into secondary and tertiary bronchi
primary bronchi - extrapulmonary
secondary and tertiary bronchi - intrapulmonary
Primary bronchi are similar in structure to trachea

Question 15

Function - gas exchange

Answer 15

Taking in O2 and eliminating CO2
Also moistens air via glandular secretions to prevent desiccation of tissues
Warms air and cools body
Filters air (mucociliary escalator)

Question 16

Function - body temperature control

Answer 16

in some species

horse: 20% of heat generated during exercise is exchanged across lung surface

Question 17

Metabolic functions

Answer 17

inactivates bradykinin, serotonin, prostaglandins, nEpi

ACE converts A-I to A-II (blood pressure regulation)

Question 18

Functional adaptation - gas exchange

Answer 18

must have thin walls (i.e. alveoli)

Question 19

Functional adaptation - moistening of air

Answer 19

requires glands

simple tubuloalveolar/tubuloacinar serous or seromucous glands

Question 20

functional adaptation - filtering of air

Answer 20

hair, mucous, and cilia (particles deposited/removed)
mucous - sticky - trap foreign substances
cilia - move it toward pharynx (swallowed or coughed up)
sneezing clears nasal cavity
process = mucociliary escalator

Question 21

functional adaptation - phonation

Answer 21

production of sound

possible due to vocal apparatus

Question 22

Conducting portion

Answer 22

involved in moving air
part of tract from nasal cavity thru terminal/tertiary bronchiole in lung
specific portions are responsible for olfaction and phonation

Question 23

transitional portion

Answer 23

present only in some animals (carnivores, monkeys)

consists of respiratory bronchioles (both conduct air and exchange gases)

Question 24

respiratory/exchange portion

Answer 24

region of gas exchange

consists of alveolar ducts, alveolar sacs, alveoli

Question 25

Nasal cavity - vestibule

Answer 25

most rostral part of nasal cavity short and transitional stratified squamous epithelium - continuous with skin site of transition from keratinized stratified squamous of the skin to mucous membrane (non-keratinized) of nasal cavity hairs, sweat glands, sebaceous glands in cutaneous portion

Question 26

Nasal cavity - conducting region

Answer 26

makes up bulk of nasal cavity conchae - lines by PSC with goblet cells, non-ciliated cells, brush cells (sensory) and basal cells branched tubuloalveolar mixed (mostly serous) glands present erectile tissue common - usually collapsed but becomes engorged with blood under neural ST (acts as heat transfer, but decreases air flow) inhaled heavy particles removed here via cilia (may metabolize/detoxify compounds) conchae - shelves of tissue extending from lateral wall/cribiform plate toward septum to increase SA of nasal cavity core of conchae - bone, hyaline cartilage surrounded by loose to coarse CT with rich vascular supply, glands, and nerves convex surface of conchae - exposed to air - numerous tubuloalveolar serous glands, many blood vessels concave surface - unexposed - fewer glands, less erectile tissue

Question 27

Nasal cavity - olfactory region

Answer 27

dorsocaudal part of nasal cavity lined by thick PSC epithelium w/goblet cells associated w/ethmoconchae

Question 28

Ethmoconchae

Answer 28

Core: bone Respiratory surface - thin layer of CT, PSC with goblet cells and cilia Olfactory surface - tall PSC epithelium w/3 difft cell populations Basal cells - cuboidal with tonofilaments and free ribosomes. May replace other cell types Olfactory/neurosensory cells - bipolar neurons - give rise to nonmyelinated olfactory nn. - dark staining nucleoli and apex of cell has long, non-motile modified cilia Supporting/sustentacular cells - tall, narrow base, oval nucleus, positioned apically, microvilli - pigment granules are common - support olfactory cells mechanically and metabolically

Question 29

Larynx - epithelium

Answer 29

PSC distal to level of vocal fold | vocal fold = where stratified squamous is present

Question 30

Larynx - lamina propria

Answer 30

many elastic fivers present in CT | nodules can be here

Question 31

Larynx - tunica muscularis

Answer 31

striated muscle | cartilagenous framework - hyaline and elastic

Question 32

Larynx - tunica adventitia

Answer 32

loose CT

Question 33

Bronchi - Tunica mucosa/submucosa

Answer 33

Epithelium - changes from ciliated PSC to ciliated simple columnar. Number of goblet cells decrease from proximal to distal Lamina propria - thin layer of CT w/many leukocytes and capillaries (also lymphoid nodules) Muscularis mucosae - smooth muscle oriented circularly and/or spirally - contracts in asthma tunica submucosa - loose CT w/elastic fibers and simple tubuloalveolar mixed serous glands (=bronchial glands) that secrete a watery, protein rich secretion cartilage plates - decrease in size and become more irregular in shape distally

Question 34

Bronchioles - definition

Answer 34

``` air conducting ducts arise from bronchi branch into several generations end as terminal bronchioles NO cartilage in walls ```

Question 35

Broncioles - epithelium

Answer 35

ciliated simple columnar/cuboidal cilia disappear as terminal bronchioles become respiratory bronchiole Goblet cells - decrease distally until absent in terminal bronchioles Ciliated cells - most numerous - decrease in number distally Bronchiolar secretory cells (Clara cells) - increase distally - dome shaped apices that protrude into lumen - secrete surface-active lipoprotein to prevent luminal adhesion - metabolize/detox xenobiotics Brush cells - columnar cells w/microvilli - basal surface plays sensory role - in synaptic contact w/afferent nerve endings

Question 36

Bronchioles - lamina propria

Answer 36

loose CT many lymphocytes and elastic fibers no cartilage or glands

Question 37

Bronchioles - muscularis mucosae

Answer 37

smooth ms. 1 layer thick in tertiary/terminal bronchiole constricts in asthma

Question 38

Bronchioles - tunica submucosa

Answer 38

loose CT | many elastic fibers

Question 39

Bronchioles - innervation

Answer 39

parasympathetic - contraction of sm. ms. | sympathetic - dilation

Question 40

Transitional zone

Answer 40

between conducting and respiratory

Question 41

Respiratory bronchiole

Answer 41

both conducting and gas exchange similar to terminal bronchiole - BUT alveoli interrupt < half of wall Ciliated and Clara cells predominate well developed in monkeys and carnivores, poorly developed in horse and man

Question 42

Respiratory zone

Answer 42

where most of gas exchange occurs

Question 43

Alveolar ducts

Answer 43

similar to respiratory bronchiole, but alveoli interrupt more than half of the wall

Question 44

Alveoli

Answer 44

functional unit where gas exchange occurs spherical structures lined by alveolar epithelium two cell types: type I and type II pneumocytes Interalveolar septum - wall b/t 2 adjacent alveoli and contains capillaries, fibroblasts, reticular fibers, and MPs/lymphocytes endothelial cells - 30% of alveolar wall - continuous and non-finestrated

Question 45

Type I Pneumocytes

Answer 45

8% of cells in alveolar wall, but cover 97% of alveolar surface major cell type in alveoli squamous tight junctions - prevent fluid leakage into air space function in gas exchange readily permeable to gases

Question 46

Type II Pneumocytes

Answer 46

``` =Great alveolar cells 16% of cells, but 3% of alveolar lining cuboidal cells interposed b/t type I pneumocytes bulge into alveolar lumen Lamellar bodies in cytoplasm - synthesized and released apically Prominent golgi and rough ER Produce surfactant - coats alveoli and lowers surface tension, preventing collapse of alveoli - there is constant turnover of surfactant ```

Question 47

Alveolar macrophages

Answer 47

=dust cells 10% of alveolar wall cells derived from monocytes that migrate from capillaries In alveolar wall and alveolar lumen Contain phagocytized inclusions - e.g. dust and airborne particulates ^ in heart failure ==> "heart failure cells"

Question 48

Gas exchange barrier

Answer 48

3 layers in alveolar wall: alveolar epithelial cell fused basement membranes (type I epith and endothelium) capillary endothelial cell

Question 49

Alveolar pores

Answer 49

help alveoli communicate w/each other | equalize pressure b/t alveoli

Question 50

Neuroendocrine cells

Answer 50

``` small, contain dense granules in epithelia from larynx and bronchiole-alveolar junction Part of APUD cells involved in paracrine and regulatory functions not visible in routine staining occur single or in small groups some cells are innervated can give rise to bronchial carcinoma ```

Question 51

Blood supply - arterial

Answer 51

Pulmonary - low pressure system - few elastic/collagen fibers - receives entire RV output Bronchial - supplies large bronchi - major pulmonary blood vessels and lymph nodes - bronchial-esophageal is a branch of intercostal a.

Question 52

Blood supply - venous

Answer 52

all pulmonary vv

Question 53

Pulmonary lymphatics

Answer 53

Throughout interstitial | not in interalveolar septae

Question 54

Innervation

Answer 54

GVE from vagus nerve and thoracic nn from sympathetic trunk innervate respiratory sm. ms. GVA carried primarily in the vagus originate from mecahnoreceptors in lung and conductive passages