Respiratory System Flashcards
What does the respiratory system do?
bring oxygen to blood in lungs or gills and expel CO2 from the blood
Characteristics that make lungs able to exchange gases.
contains large surface area by folding and refolding upon itself; also exhibits:
steep diffusion gradient for O2 and CO2
short diffusion distances (thin walls)
high degree of vascularization
coordinated air and blood movement
Where does diffusion of gas occur
across 2 layers of thin simple squamous epithelium with basal lamina
gases must be dissolved in fluid in respiratory tract to diffuse (causes water loss problems in tetrapods)
max distance of diffusion barrier
2.5 microns
respiratory structures in terrestrial, aquatic, and amphibious crawlers
terrestrial: lungs
aquatic: gills. In some fish buccal cavity and anterior stomach serve as accessory respiratory structures (also some fish possess lungs)
skin (cutaneous) is also a respiratory structure in amphibians (especially lungless salamanders)
What is the respiratory “terrestrial situation”
bidirectional flow (expired and inspired air over some surfaces), except in birds (unidirectional crosscurrent system)
What is the respiratory “aquatic situation”
water flow over gills is unidirectional countercurrent exchange= blood and water pass in opposite directions.
Why is countercurrent exchange better than unidirectional or crosscurrent?
in unidirectional flow, all we can do is equilibrate the O2 concentration
when the flow is in the opposite direction, the creature can extract more than ‘equilibrium’ levels of oxygen.
Describe the terrestrial respiratory system (basic)
consists of paired lungs and branching system of airways bringing air to respiratory surface for gas exchange
Sequence the terrestrial respiratory system for mammals.
Nasal cavity pharynx larynx trachea bronchi bronchial tree: secondary bronchus tertriary bronchus bronchiole terminal bronchiole respiratory bronchiole alveolar duct alveolar sac alveolus
extrapulmonary vs intrapulmonary
the point where the bronchi penetrate the lungs (between primary and secondary bronchus)
Describe the nasal cavities
paired, divided by nasal septum
open to outside via external (anterior) nares. open interiorly to nasopharynx via internal nares =choanae)
walls of nasal vacuities of hyaline cartilage and bone to keep them open
3 regions of the nasal cavities
vestibule= lined by stratified squamous with filtering hairs, sweat and sebaceous glands present. mostly same as outside.
nasal passages: olfactory region
contains olfactory mucosa, dorsally situated (superior)
respiratory region: contains respiratory mucosa, ventrally situated.
Describe olfactory epithelium
pseudo stratified columnar containing:
olfactory receptor cells
sustentacular cells
basal cells
no goblet cells present
nuclear-free border 1/5 height of epithelium
L. propria with serous bowman’s glands to rinse away stimulus molecules and dissolve incoming stimulus molecules
thicker than respiratory epithelium
olfactory receptor cells
modified bipolar neurons with dendrite that extends to free surface with olfactory cilia and axons extending into lamina propria; large spherical nucleus found in middle of epithelium
Describe respiratory epithelium
ciliated PSC with goblet cells
nuclear free border 1/3 of epithelial height
located ventrally in nasal cavity and lines larger respiratory tubes
Describe nasal cavity respiratory epithelial lamina propria.
in nasal cavity, lamina propria composed of cavernous (erectile) tissue- swelling gives plugged nose.
l. propria also contains mucoserous glands
Nasal conchae
turbinates
shelves of bone projecting medially from lateral walls of nasal cavity
covered by a mucous membrane
act to increase surface area of nasal cavity
function as countercurrent heat exchanger: exhaled air temperature is less than body temperature and therefore decrease respiratory water loss (since cold air holds less water than warm air)
Describe the larynx
connects pharynx to trachea
consists of a tube supported by cartilage interconnected by dense CT and skeletal muscle; functions to guard respiratory tract from possible food entry and produces voice
Vestibular folds
of mucous membrane, extend from lateral walls (false vocal cords)
they lie above and protect the vocal folds (cords) beneath.
lined by respiratory epithelium
vocal ligaments
elastic fiebrs in vocal cord with skeletal muscle at core.
contraction of muscle changes tension and length of cords and opening between them, thereby creating changes in voice.
vocal folds lined by stratified squamous epithelium
epiglottis
extension of anterior wall of larynx, supported by elastic cartilage plate; covers opening to larynx to keep food out
Describe the trachea
Shares a large number of characteristics with lesser ducts
Contains mucosa, submucosa, fibro-cartilaginous coat (tunic) of adventitia and cartilage
Mucosa and submucosa separated by an elastic membrane
SEE HANDOUT FOR CROSS-SECTIONAL STRUCTURE OF RESPIRATORY TUBES
5 cell types of the respiratory tract
ciliated columnar cells goblet cells basal cells brush cells (need EM to see) small granule cells (need EM to see)
