Senario Four - The Respiratory Tract Flashcards
what separates the lungs?
heart and the mediastinum
what are the surfaces of the lungs?
costal surface - contact with ribs
mediastinal surface - centrally
what is present on the mediastinal surface of the lung?
the hilum (or ROOT) - bronchi, blood vessels, lymphatics and nerves - held together by pleura and CT
cardiac notch on (L) side - due to apex of the heart
Name the lung lobes and the fissures dividing them
right lung: superior lobe - horizontal fissure, middle lobe - horizontal and oblique fissures, inferior lobe - oblique fissure
Left lung: superior lobe and inferior lobe divided by single oblique fissure
what is a bronchopulmonary segment
further division of the lungs to form:
10 segments on the right
9 on the left
each supplied by their own tertiary bronchi
what is a lobule?
a division of a bronchopulmonary segment supplied by
1x lymphatic vessel, 1x arteriole, 1x venue and 1x nerve
wrapped in connective tissue.
Describe the function of the nose
warm, moisten and filter incoming air
detect olfactory stimuli
modifying speech vibrations
describe the structure of the nose
bony and hyaline cartilage framework - to keep it patent
inferior respiratory region - lined with ciliated psuedostratified columnar epithelium & lots of goblet cells
Anterior vestibule - coarse hairs to filter out large particles
what is the purpose of the inferior respiratory region of the nose?
goblet cells produce mucus which traps debris
ciliated psuedostratified columnar epithelium waft trapped particles down to the pharynx - to be spit out or swallowed.
what is the structure of the pharynx?
from the internal nares to the level of the cricoid cartiliage
nasopharynx - ciliated psuedostratified columnar epithelium
oropharynx and laryngopharanx - non-keratinised stratified columnar epithelium
funnel shaped 13cm tube
skeletal muscle lined with mucous membranes
what is the function of the pharynx
passageway for air and food
resonating chamber for speech sounds
tonsils for immunological reactions against foreign invaders
what is the structure of the larynx
short passageway between laryngopharynx and the trachea
supported by 9 pieces of cartiliges
coated in non-keratinised stratified squamous epithelium superior to vocal cords
ciliated psuedostratified columnar epithelia inferior to vocal cords - with goblet cells and basal cells
what is the structure and function of the epiglottis?
leaf shaped elastic cartilage - coated in epithelium
when pharynx and larynx rise, epiglottis moves down to form lid over glottis - blocking entry to the trachea and vocal cords
what is the function of the larynx
conducting pathway for food and air
what are the 9 cartilages of the larynx?
thyroid
epiglottis
cricoid
2x arytenoid
2x cuneiform
2x corniculate
Describe the shape and location of the trachea?
12cm long
2.5 cm wide
anterior to oesophagus
from larynx to T5 before divides into L and R bronchi
what are the 4 layers of the trachea, and their structure?
mucosa - internal layer of ciliated psuedostratified columnar epithelium, with underlying lamina proprietary (elastic and reticular tissues)
submucosa - areolar connective tissue containing seromucosa glands
hyaline cartilage - 16-20 C shaped rings - deficient posteriorly
- coated in fibromuscular membrane - with SM & elastic tissue
adventitia - areolar CT - joins trachea to surrounding tissues
what is the function of the mucosa?
protects against dust
what is the function of the submucosa?
produce mucus
what is the function of the hyaline cartilage?
SM contraction to adjust trachea diameter
provide semi-rigid support
allow the passage of food down oesophagus
what is the function of the adventitia?
joins trachea to surrounding tissues
what is the structure of the main, lobar and segmental bronchi?
ciliated psuedostratified columnar epithelium
main bronchi - C shaped cartilage
lobar and segmental bronchi - plates of cartilage to maintain patency
what is the pathway of the main bronchi?
divide into L and R from trachea at T5 - at the point of the carina
R bronchi is more vertical, shorter and wider than L - more likely to aspirate
what is the carina
area of division between L and R bronchi - highly sensitive - initiates the cough reflex
what is the pathway of the lobar bronchi?
when the main bronchi enter the lungs - divide into:
(R) - superior, middle and inferior lobar bronchi
(L) - superior and inferior lobar bronchi
what is the pathway of the segmental bronchi?
divisions of the lobar bronchi to supply the bronchopulmonary segments - 10 on R, 9 on L
what is the structure of the large bronchioles?
simple, ciliated columnar epithelium
- contain goblet cells
- contain more SM than bronchi
what is the structure of the small bronchioles?
simple, ciliated columnar epithelium
- contain NO goblet cells
- contain more SM than large bronchioles
what is the structure of the terminal bronchioles?
non-ciliated columnar epithelium
large amounts of SM
contain Clara - club cells
what is a clara cell
protects against inhaled carcinogens
produce surfactant
act as stem cells to produce epithelia
what is the pattern of structural changes throughout the conducting system?
ciliated psuedostratified columnar epithelium in main lobar and segmental bronchi
–> simple, ciliated columnar with goblet cells in large bronchioles –> no goblet cells in small bronchioles
–> non-ciliated simple columnar in terminal bronchioles
large amounts of cartilage decreases down conducting pathway - no cartilage in terminal bronchi
as cartilage decreases, smooth muscle increases
what is the role of the smooth muscle in the conducting pathway
forms a spiral band to maintain patency
- lack of cartilage can mean in asthma the SM spams can close off airways
what are the 5 defense mechanisms for the respiratory tract?
cough sneeze MCE wandering macrophages antiproteases
what is the effect of the sympathetic nervous system on the conducting system
fight or flight respose
during exercise
cause release of A and NA to relax SM
what is the effect of parasympathetic input to the conducting system?
release of histamine during allergic reactions
causes SM constriction
where does the conducting system end and the gas exchange system starts
ends at terminal bronchioles
starts in the respiratory bronchioles –> alveolar ducts –> alveoli
where is the MCE
all non-gas exchange surfaces
facilitated by ciliated cells
From terminal bronchioles to the larynx
what does the MCE do
Moves particles which have been trapped in mucous towards the mouth by wafting of cilia
once in the mouth either coughed out or swallowed and destroyed by stomach acid
how much mucous is produced daily?
20-30ml
what is the mucous blanket?
a layer in which the cilia project into
has two layers:
- sol layer - watery component to allow cilia wafting
- gel layer - sticky layer to trap particles
where does most wafting occur?
in the sol layer of the mucous blanket
where is the mucous of the gel layer produced?
goblet cells and mucous cells
what are the 6 parts of a reflex arc?
receptors, afferent, CNS, efferent, effector, action
what are the receptors in the cough reflex
larynx, carina, pleura, pericardium, diaphragm and auditory canal
respond to irritants in the respiratory tract or when mucous production is too high
what is the afferent to the cough reflex?
the vagus nerve
where does the CNS respond to cough reflex?
modulated in the cortex & cough centre in medulla oblangata
what is the efferents and effectors to the cough reflex?
1) vagus to superior largengeal nerve - laryngeal adductors
2) phrenic nerve - C3, 4, 5 - diaphragm
3) spinal motor nerves - T1- T11 - internal and external intercostals & T6-T12 - abdominals (oblique and rectus abdominus)
what is the action of the cough reflex?
laryngeal adductors - glottic closure
diaphragm and external intercostals - deep inspiration
internal intercostals and abs - forced expiration
what are the 4 stages to the cough sequence?
- deep inspiration (near total lung capacity)
- glottic closure
- isometric contraction of abdominals
- - glottis remains closed and increase in intraabdominal pressure - sudden opening of glottis - explosive expiration
- - creates shearing forces (>100mph)
- - unsticks secretion from airways
describe the structure of the respiratory bronchioles
microscopic subdivision of terminal bronchiole
simple cuboidal cells changing to simple squamous cells further down
no cilia and no goblet cells
describe the function of respiratory bronchioles
begin the respiratory zone
alveoli bud from the walls
gas exchange surface
describe the structure of the alveolar duct?
subdivisions of the respiratory bronchioles - with a terminal dilation of the alveolar sac
simple squamous epithelium
function of the alveolar duct?
gas exchange surface - passage way for air
produce surfactant
describe the structure of an alveolar sac?
the terminal dilation of the alveolar duct
forms outpouchings - the alveoli
simple squamous epithelium
function of the alveolar sac
gas exchange, passage way for air and surfactant production
