Lung Histology

Question 1

Two divisions of the respiratory tract + definitions

Answer 1

conducting zone- pathway taken by inspired air from the mouth and nose to the gas exchange region of the lungs

respiratory zone- gas exchange region

Question 2

what does the conducting zone consist of?

Answer 2

nasal passages, pharynx, larynx, trachea, bronchi and most of the bronchioles

Question 3

what does the respiratory zone consist of?

Answer 3

respiratory zone proper, formed of the bronchioles, alveolar ducts and definitive alveoli

Question 4

anatomical divisions of the respiratory tract + what they consist of

Answer 4

upper respiratory tract- extends down to , including the larynx

lower respiratory tract- trachea, lungs and respiratory tree

Question 5

epithelia in the nasal passage

Answer 5

pseudostratified columnar epithelium except for the vestibule which shows keratinizing stratified squamous epithelium

Question 6

what is respiratory type epithelium?

Answer 6

pseudostratified columnar epithelium that is present in the upper respiratorytract

Question 7

where is the respiratory type not present?

Answer 7

orthopharynx, vocal cords and anterior margins of the epiglottis

Question 8

what epithelia are present here?

Answer 8

stratified squamous

Question 9

what supports respiratory epithelia?

Answer 9

lamina propria

Question 10

what does the lamina propria and epithelia form?

Answer 10

mucous membrane

Question 11

functions of the mucosa?

Answer 11

warm and humidify inspired air

provide an immunological defense and a ciliary clearing mechanism against infection and inspired particles

provide a sense of smell- olfactory epithelium

Question 12

what is found beneath the mucosa?

Answer 12

submucosa

Question 13

what is present in the lamina propria? + functions

Answer 13

blood vessels- warm the surrounding air

elastin- allow recoil

Question 14

what is secreted? + where from

Answer 14

mucus

submucosal glands in the submucosa

Question 15

mucus definition

Answer 15

viscous fluid containing glycoproteins

serous components contain immunoglobulins, lysozymes and enzymes directed against bacteria

Question 16

mucus function

Answer 16

lines the respiratory tract up until the ends of the bronchi

Question 17

what is present behind the C shape hyaline cartilage in the trachea?

Answer 17

trachealis muscle

Question 18

cells present in the upper respiratory tract epithelium

Answer 18

cilliated cells + goblet cells

Question 19

cilliated cells function

Answer 19

move mucus continually towards the pharynx via the muco ciliary escalator

beat upwards and outwards

move inhaled particles, liquids and microorganisms within the viscous layer out of the body

Question 20

goblet cell function

Answer 20

produce a viscous film containing mucins, Igs, lysozymes and anti proteases which disable bacterial functions

produce mucinogen that becomes hydrated to mucin when released

Question 21

difference between bronchi and trachea

Answer 21

almost none

Question 22

difference between bronchi and bronchioles

Answer 22

bronchi contain cartilage in their walls

bronchioles lack cartilage but have smooth muscle in their walls

Question 23

other bronchiole structures

Answer 23

no submucosal glands

incomplete bundles of smooth muscle form rings

simple columnar epithelium slowly become cuboidal

ciliated cells persist

goblet cells disappear

Question 24

acini definition

Answer 24

chief unit of lung function capable fo gaseous exchange

consisting of respiratory bronchioles, alveolar ducts and alveoli

Question 25

what are the respiratory bronchioles also termed? + why?

Answer 25

transitional airways

conduct air (bronchiolar like) but also participate in gaseous exchange (alveolar like)

Question 26

gross alveoli structure

Answer 26

many sacs

pores of Kohn provide a potential route of communication between alveoli

within septa of adjacent alveolar walls abundant capillaries are present

Question 27

how many cell types in alveoli epithelium?

Answer 27

three

Question 28

what cells? + type and how abundant

Answer 28

Type I alveolar cells- squamous, cover most of alveolar wall

Type II alveolar cells- cuboidal, account for less than 10% of alveolar surface

macrophages

Question 29

other name for alveolar cells

Answer 29

pneumocyte

Question 30

Type I pneumocyte structure

Answer 30

very thin cystoplasm

stretched over and conform to the shape of capillaries

Question 31

what do the type 1 pneumocytes and blood vessles form? + structure

Answer 31

blood-air barrier

thin alveolar walls and thin endothelium

basal lamina of each cell fuse together to form a single layer

Question 32

type II pneumocyte functions

Answer 32

secrete surfactant

Question 33

surfactant structure

Answer 33

mixture of lipids and proteins

Question 34

surfactant function

Answer 34

forms a monolayer on the inner alveolar surface and reduces surface tension

prevents the collapsing of alveoli during exhalation

Question 35

location of alveolar macrophages

Answer 35

abundant within the alveoli, lesser extent in the septa

Question 36

macrophage function

Answer 36

phagocytes directed against irritants, particulate matter and microorganisms

Question 37

structure of pulmonary circulation

Answer 37

abundant capillaries within the septa

supported by collagen and elastic fibres

Question 38

explain cystic fibrosis

Answer 38

autosomal recessive disorder that leads to airway obstruction due to excessive and hyper viscous mucus secretion

mutation in CFTR

leads to chronic lung infection

Question 39

venous plexus definition

Answer 39

vascular network found in the lamina propria of the nasal cavity that heat inspired air