Respiratory Flashcards
tight junctions (zona occludens)
close off intercellular space
found at apical region of most epithelial tissue types
belt-like junction extends around the periphery of each cell
some proteins in plasma membrane are fused which forms a seal that closes off intercellular space
prevent certain molecules from passing between cells of epithelial tissue
where are the tightest tight junctions food?
epithelium of small intestine
to keep digestive enzymes and intestinal microbes from seeping into bloodstream
adhesive belt junctions (zonula adherens)
located just below tight junctions in epithelial tissue
transmembrane linker proteins attach to actin microfilaments of the cytoskeleton and bind adjacent cells
reinforce tight junctions, particularly when tissues are stretched
desmosomes
anchoring junctions which bind adjacent cells together and form an internal tension-reducing network of fibers
cells joined by linker glycoproteins (adherins)
common in cardiac muscle and epithelial tissue
gap junctions
channel between cells (connexon)
hollow cylinders of protein which connect cells
allow ions and small molecules to move directly between neighboring cells
function in intercellular communication
cytoskeleton
microtubules - cylindrical structures made of proteins
microfilaments - filaments of contractile protein actin
intermediate filaments - protein fibers
microvilli
fingerlike extensions of the plasma membrane of apical epithelial cells
each contains a core of actin filaments that extend into actin microfilaments of the cytoskeleton
occur in almost every moist epithelium of the body
where are the longest and most abundant microvilli found?
epithelia of the small intestine (for nutrient absorption and digestion) and kidneys (for ion transport)
cilia
whiplike, highly motile extensions of apical surface membranes
contain a core of nine doublets of microtubules encircling one middle doublet
doublets have attached motor proteins (dynein arms)
cilia produce propulsive stroke followed by nonpropulsive recovery
Kartagener’s syndrome
dynein arms do not form
cilia cannot propel
exocrine glands
ducts carry products of exocrine glands to epithelial surface
include: mucus-secreting glands, sweat glands, oil glands, salivary glands, liver and pancreas (secrete digestive fluids)
unicellular exocrine gland: the goblet cell
produces mucin
mucin + water = mucus
2 basic parts of a multicellular exocrine gland
epithelium-walled duct (simple or compound) secretory unit (tubular, alveolar, or tubuloalveolar)
functions of the respiratory system
absorbs oxygen from air into blood
disposes of carbon dioxide into air from blood
organs of the respiratory system
- nose, nasal cavity, paranasal sinuses
- pharynx, larynx, trachea
- lung bronchi, bronchioles, and alveoli
the nose: functions
provides an airway from respiratory filters inhaled air humidifies and warms air resonating chamber for speech houses olfactory receptors