Respiratory System Flashcards
Functions
Gas exchange body temperature control phonation olfaction metabolic function
Functional adaptations
gas exchange moistening of air warming of air filtering of air phonation
Major subdivisions
conduction portion
transitional portion
respiratory/exchange portion
Respiratory epithelia
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
Functional morphology/general organization
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
Nasal cavity - divisions
vestibule
conducting region
olfactory region
Paranasal sinuses
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)
Vomeronasal organ
=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)
Nasopharynx
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)
Larynx
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
Trachea - tunica submucosa
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
Trachea - tunica muscularis
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
Trachea - tunica adventitia
Loose to coarse CT
Bronchi
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
Function - gas exchange
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)
Function - body temperature control
in some species
horse: 20% of heat generated during exercise is exchanged across lung surface
Metabolic functions
inactivates bradykinin, serotonin, prostaglandins, nEpi
ACE converts A-I to A-II (blood pressure regulation)
Functional adaptation - gas exchange
must have thin walls (i.e. alveoli)
Functional adaptation - moistening of air
requires glands
simple tubuloalveolar/tubuloacinar serous or seromucous glands
functional adaptation - filtering of air
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
functional adaptation - phonation
production of sound
possible due to vocal apparatus
Conducting portion
involved in moving air
part of tract from nasal cavity thru terminal/tertiary bronchiole in lung
specific portions are responsible for olfaction and phonation
transitional portion
present only in some animals (carnivores, monkeys)
consists of respiratory bronchioles (both conduct air and exchange gases)
respiratory/exchange portion
region of gas exchange
consists of alveolar ducts, alveolar sacs, alveoli
Nasal cavity - vestibule
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
Nasal cavity - conducting region
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
Nasal cavity - olfactory region
dorsocaudal part of nasal cavity
lined by thick PSC epithelium w/goblet cells
associated w/ethmoconchae
Ethmoconchae
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
Larynx - epithelium
PSC distal to level of vocal fold
vocal fold = where stratified squamous is present
Larynx - lamina propria
many elastic fivers present in CT
nodules can be here
Larynx - tunica muscularis
striated muscle
cartilagenous framework - hyaline and elastic
Larynx - tunica adventitia
loose CT
Bronchi - Tunica mucosa/submucosa
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
Bronchioles - definition
air conducting ducts arise from bronchi branch into several generations end as terminal bronchioles NO cartilage in walls
Broncioles - epithelium
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
Bronchioles - lamina propria
loose CT
many lymphocytes and elastic fibers
no cartilage or glands
Bronchioles - muscularis mucosae
smooth ms.
1 layer thick in tertiary/terminal bronchiole
constricts in asthma
Bronchioles - tunica submucosa
loose CT
many elastic fibers
Bronchioles - innervation
parasympathetic - contraction of sm. ms.
sympathetic - dilation
Transitional zone
between conducting and respiratory
Respiratory bronchiole
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
Respiratory zone
where most of gas exchange occurs
Alveolar ducts
similar to respiratory bronchiole, but alveoli interrupt more than half of the wall
Alveoli
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
Type I Pneumocytes
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
Type II Pneumocytes
=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
Alveolar macrophages
=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”
Gas exchange barrier
3 layers in alveolar wall:
alveolar epithelial cell
fused basement membranes (type I epith and endothelium)
capillary endothelial cell
Alveolar pores
help alveoli communicate w/each other
equalize pressure b/t alveoli
Neuroendocrine cells
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
Blood supply - arterial
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.
Blood supply - venous
all pulmonary vv
Pulmonary lymphatics
Throughout interstitial
not in interalveolar septae
Innervation
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
