Respiratory Histology Flashcards
Conducting Airway
- what is its purpose
- what are the structures associated
purpose: functions to warm, filter and humidify the air taken in
structures:
nasal cavity
nasopharynx
oropharynx
larynx
trachea
bronchi
bronchioles (conducting and terminal)
** ends at the terminal bronchiole**
Structures within the Nasal Cavity
Vestibule
Respiratory Region
Olfactory Region
Vestibule -part of the conducting portion
- purpose
- histology
purpose: communicate with the external environment; contains hairs which act as coarse filters as the air is taken in
histology:
continuous with the skin
therefore –> epidermis is the cell layer
epidermis: STRATIFIED SQUAMOUS EPITHELIUM
contains sebaceous glands, sweat glands and hair follicles within the epidermis
Respiratory Region -nasal cavity (part of the conducting pathway)
Structure
structure: medial wall = nasal septum
lateral wall = made up of the inferior, middle and superior turbinates
** turbinates are coiled boney projections lined in mucosa**
floor = smooth and sits on the hard palate anterior to the maxilla
Respiratory Region of the nasal cavity
Histology
respiratory epithelium
- CILATED PSEUDOSTRATIFIED COLUMNAR EPITHELIUM
-GOBLET CELLS: secrete mucus
- basal cells too
** terbinates, septum and floor all contain respiratory epithelium**
- lamina propria contains seromucous glands –> vessels which drain to the surface to warm the air
-terbinates have bone at central core
Olfactory Region of the Nasal Cavity – structure
majority of the roof of the nasal cavity
- includes…
part of the superior nasal septum
superior portion of the superior
turbinate
Olfactory Region of the Nasal Cavity – histology
OLFACTORY EPITHELIUM –> contains 3 types of cells
1. basal cells
2. ciliated columnar supporting cells
olfactory neural cells
**NO GOBLET CELLS IN OLFACTORY **
Nasopharynx/Oropharynx
(of the conducting airway)
Structure
connect the nasal and oral cavities to the larynx/esophagus
Nasopharynx/Oropharynx
(of the conducting airway)
Histology
Nasopharynx: stratified squamous AND respiratory epithelium
– so the squamous shape, stratified (multiple layers)
– and the respiratory –> which was ciliated, pseudostratified and columnar in shape AND CONTAINS GOBLET CELLS (MUCOUS!!)
Oropharynx: stratified squamous epithelium ONLY
** both contain lymphoid stoma –> area of HIGH AMOUNTS of lymphocytes***
Larynx (of the conducting airway)
Structure & function
structure
-cartilage framework with ligaments to attach to each
function
- phonation (speaking)
-prevent aspiration
specific structures of the larynx & their function
- Supraglottis (protection)
- epiglottis (protective flap)
- false vocal cords
- ventricles (the space between
false and true cords)
- Glottis (phonation)
- true vocal cords –> sound
- Subglottis
from the glottis to the cricoid cartilage
Larynx (condcuting airway)
histology
- false vocal cords –> respiratory OR squamous epithelium
- ventricle –> respiratory epithelium only
- true vocal cords –> stratified squamous epithelium
- mucoserous glands throughout all three areas to supply mucous
Trachea (conducting airway)
Structure & Histology
structure:
- 25 cm in length
- c-shaped cartilaginous rings in the anterior (hyaline cartilage)
- branches at the carina into primary bronchi
histology:
- lined with respiratory epithelium (goblet cells !!)
outline the pathway of the trachobronchial tree (all still part of the conducting pathway)
trachea
primary bronchi (mainstem)
secondary bronchi (lobar)
tertiary bronchi (segmental)
conducting bronchioles
terminal bronchioles
histology of the bronchi
(primary - mainstem, secondary -lobar, tertiary-segmental)
respiratory epithelium
- contains cilated, psuedostratified, columnar cells
- contains goblet cells
- contains basal cells
histology of the bronchioles
(conducting bronchioles, terminal bronchioles)
bronchiolar epithelium
- cilated, psuedostratified, columnar cells
- clara cells (club cells): responsible for secreting PROTEINS that protect the bronchiole lining AND act as stem cells to produce new damanged epithelial cells
** NO GOBLET**
primary function of the respiratory portion of the respiratory tract
gas exchange
(where are in comparison, the conducting airway was responsible for filtering and warming the air)
components of the respiratory portion of the tract
respiratory bronchioles
alveolar duct
alveolar sac (the termination of a duct)
Respiratory Bronchiole (RB) and Alveolar Duct (AD)
function and histology
Respiratory bronchiole (RB)
function: gas exchange AND conduction
histology:
- simple, cuboidal epithelium
-clara cells still present (protein protection of the bronchioles)
-sometimes rare ciliated cells
** simple = single layer of cells**
Alveolar Duct (AD)
function: connection between the RB and the alveolar sac
histology:
-simple, cuboidal epithelium
- NO clara or ciliated cells
Alveolar Sac
structure and function
-a collection of individual alveolus (multiple = alveoli)
- each alveolus is wrapped in capillary network
- alveolar wall made of elastic fibers for stretch and recoil
- responsible for gas exchange with the capillary surrounding
histology of the alveoli
3 cell types present
1. Type 1 pneumocyte: squamous cell
- responsible for gas exchange
** squamous = thin = good for gas exchange!!**
- Type 2 pneumocyte: cuboidal cell
- responsible for producing surfactant (decrease surface tension– prevents collapse alveoli)
- alveolar macrophage: a macrophage
- scavenges for invaders
** alveolar macrophages can be pigmented –> such as with tar in smokers or hemosiderin in pulmonary hemorrhage( trying to eat up and breakdown the blood**
what is alpha-1- antitrypsin
- an enzyme produced by the liver
- responsible for protection tissue from the breakdown process of neutrophil elastase during inflammation
in inflammation –> neutrophil elastase breakdown forgein objects – but sometimes breakdown own body –> A1A’s are released to help combat that breakdown in the lung tissue
what happens in A1A deficiency
- the body produces A1A–> but its mutated
- the mutated A1A cannot leave the liver
- therefore it cannot help to protect in the respiratory tract tissue , results in damange
how is A1A related to emphysema
- A1A can cause a specific type of emphysema –> panacinar emphysema
- this is when the permanent enlargement of the air spaces occurs first at the DISTAL structures –> alveolus and alveolar ducts then later to the bronchioles
what is normal emphysema
- perminent enlargement of the air spaces past the terminal bronchioles, destroying the walls without fibrosis
- centriacinar emphysema –> when the more proximal parts of the acunus (respiratory bronchioles) are damanged before the alveoli are
emyphsema results in enlarged air spaces within the alveoli –> becuase the alveolar walls are destroyed –> leading to decreased gas exchange because decreased SA
clinical information about A1A deficiency
- onset between 20-50
-SOB with activity - unable to exercise
-wheezing - 15% develop cirrhosis (because buildup of A1A in the liver leads to damage as it cant leave)
- increase HCC risk
dx. with an A1A blood test to see in those without obvious symptoms
