1- histology Flashcards
what is respiratory epithelium?
pseudostratified columnar epithelial ciliated with goblet cells
what are goblet cells?
unicellular glands, they secrete mucous and keeps surface moist (found in respiratory epithelium)
what special cells are in root of nasal cavity?
specialised olfactory epithelium which is where get neuro-olfactory cells and get smell
what is function of nasal cavity?
- warming
- moistening
- filtering the inspired air
what is the initial part of nasal cavity called and what is it lined by?
called the vestibule = lined by keratinized stratified squamous epithelium
what changes from the vestibule to deeper into nasal cavity?
vestibule = keratinised stratified squamous epithelium
deeper= loses keratin and changes epithelial cells to respiratory epithelium (pseudostratified ciliated columnar epithelial with goblet cells)
what are seromucosal glands?
serous glands =produce liquid
mucous glands = produce sticky mucous
seromucosa glands = produce both
what causes a blocked nose?
the lamina propria, a band of loose connective tissue containing seromucous glands (SM) and thin-walled venous sinuses (V) which can quickly engorge with blood and ‘block’ the nose.
what is lamina propria?
a band of loose connective tissue containing seromucous glands & thin walled venous sinuses
*found under respiratory epithelium
what lines the oral pharynx?
oral pharynx = middle part of pharynx that has both air and swallowed food
- this means it must resist abrasion so lined by non-keratnized stratified squamous epithelium
what is general rule that i can use to try remember when keratanized or not?
keratonized = dry surfaces
non-keratonized = wet surfaces
what lines the epiglottis?
lid bit of larynx (skeleton of cartilage)
the anterior part (sublingual part) of epiglottis touches tongue so lines by same as oral pharynx and is lined by non-keratinized stratified squamous epithelium
- this covers anterior surface over the apex and the upper part of posterior surface
the larynx walls are made of cartilage and muscles & lined with respiratory epithelium - what is the exception to this?
the vocal cords that are covered with stratified squamous epithelium
what composes the vocal cords?
true vocal cords = continuous with posterior surface of epiglottis so respiratory epithelium and seromucous glands
false cords = ventricles are spaces between the cords - bilateral and after that the cells change to non-keratinized stratified squamous epithelium
what is trachea made up of?
15-20 C shaped cartilaginous rings, they’re deficient posteriorly (bits without cartilage) to allow expansion. These deficient bits have fibroelastic tissue & smooth muscle (trachealis muscle)
the rest of it has the normal respiratory epithelium then lamina propria (connective tissue & abundant elastic fibres) then submucosa of connective tissue with seromucous glands then cartilage then adventitia
what type of cartilage is in trachea?
hyaline
what are the different parts of the bronchi?
part outside lung = extra-pulmonary bronchi (structure similar to trachea)
part inside = intrapulmonary bronchi
what are the 2 main changes between extrapulmonary bronchi and intrapulmonary bronchi?
extra to intra
- smooth muscle = muscularis consisting of a ring of smooth muscle
- cartilage = the rings are replaced by irregularly shaped cartilage plates
what is the wall of bronchus made up of?
respiratory epithelium, lamina propria, muscularis consisting of smooth muscle & submucosa with adipose tissue and some seromucous glands
*also irregularly places cartilage plates
when does bronchi turn to bronchiole?
bronchiole form when 1 mm
what do bronchioles consist of?
- lack cartilage & glands but may contain a few goblet cells in initial bit
epithelium decreases in height from columnar to cuboidal as you progress down
- lamina propria composed of smooth muscle, elastic & collagenous fibres
what is main difference between bronchi & bronchioles?
no cartilage
what is the smallest bronchiole that before gas exchange?
terminal bronchioles
what are the first part of bronchioles that have respiratory function?
respiratory bronchioles
how do bronchioles play a role in asthma attacks and allergic reactions?
the smooth muscle of bronchioles respond to parasympathetic innervation, histamine and other factors by contracting and constricting the diameter of the bronchiole
what makes up the terminal bronchioles?
lined with cuboidal ciliated epithelium and contain non-ciliated club cells (previously called Clara cells) that project above the level of adjacent ciliated cells
what are the roles of club cells?
- Stem cells
- Detoxification
- Immune modulation
- Surfactant production
list the cells that alveoli are made up of
- type 1 alveolar cells
- type 2 alveolar cells
- alveolar macrophages
*alveolar cells also called pneumocytes
when does gas exchange start?
in alveoli which are associated with respiratory bronchioles, alveolar ducts and alveolar sacs
what are respiratory bronchioles lined with?
cuboidal epithelium
what part of bronchial tree are responsible for spongy nature of lungs?
alveoli (about 300 million in each lung)
what are type 1 alveolar cells?
simple squamous epithelium that lines alveolar surfaces (covering 90% of surfaces)
provide minimal thickness that is permeable to gases
what are type 2 alveolar cells?
polygonal in shape, the free surface is covered by microvilli and the cytoplasm displays dense membrane bound lamellar bodies which contain surfactant.
The surfactant is released by exocytosis and spreads over the pulmonary surface to reduce the surface tension at the air-fluid interface. This reduces the tendency for the alveoli to collapse at the end of expiration.
where are alveolar macrophages found? and what is their function?
in the septa or migrating over the luminal surfaces of the alveoli, phagocytosing inhaled particles that may have escaped entrapment by the mucous lining of the airway
- they then migrate up the bronchial tree, transported by ciliary action, to the pharynx where they are swallowed or will move into the septal connective tissue where they will remain
what is in septa of alveoli?
type 2 alveolar cells and macrophages - also permeated by capillary networks
what does the air blood barrier consist of?
type 1 cells, the endothelial cell & basal lamina of each
what is the visceral pleura?
= multi layered and immediately surrounding lungs & faces parietal pleura which lines thoracic cavity (pleural cavity between the 2)
outer layer = simple squamous epithelium called mesothelium backed by layers of fibrous and elastic connective tissue
