Lecture 8 - Role of the airway in conducting clean air to the lungs

Question 1

what are the 4 different cell types within respiratory epithelium?

Answer 1

outlying cells - pseudostratified columnar epithelium
within epithelium - GOBLET cells.
within epithelium - BASAL cells
within epithelium - BRUSH cells

Question 2

do pseudostratified cells have cilia? if so what is there function?

Answer 2

yes - function to move mucus towards the mouth.

Question 3

what is the function of goblet cells? do they have cilia?

Answer 3

mucus secretion, no cilia

Question 4

what is the function of basal cells, where do they attach to?

Answer 4

attach at base of epithelium, stem like cell that can differentiate into any other epithelial cell

Question 5

what is the function of brush cells?

Answer 5

they are a sensory cell with thick microvilli, sense foreign material associated with trigeminal nerve

Question 6

what are the two types of glands? where are they located?

Answer 6

glands: sit ontop of nasal septum
1. serous - watery gland secretions
2. mucus - thick, trap foreign particles

Question 7

what are the 3 cell types within the olfactory mucosa?

Answer 7

1. olfactory cells
2. support cells
3. basal cells

Question 8

how does the olfactory cell detect and process odours to the brain?

Answer 8

microvilli of olfactory cell protrude into nasal cavity
–> receptors for odours –> trigger AP when odour bind –> if AP reach threshold, AP will be sent down to olfactory nerve to brain

Question 9

what is the cell shape and function of basal cells within the olfactory mucosa?

Answer 9

cuboidal cell, function as a regenerative cell

Question 10

what is the main function of the olfactory mucosa?

Answer 10

sense odours

Question 11

what is the function of support cells?

Answer 11

provision of metabolic support?

Question 12

describe the mylenation of the olfactory cell?

Answer 12

unmyelniated

Question 13

what are the 5 microscopic layers of the trachea?

Answer 13

1. epithelium (w/ basement membrane)
2. laminapropria
3. smooth muscle
4. cartilage
5. adventitia

Question 14

what is the function of the laminapropria?

Answer 14

provide nourishment to airway wall e.g. blood vessels, lymphatics

Question 15

house is the smooth muscle bound? what is its function

Answer 15

bound by lamina propria, contracts to make airway smaller, also engaged in immune response

Question 16

what type of cartilage is the cartilage within the trachea, what is its function?

Answer 16

hyaline cartilage

stops trachea from collapsing under negative pressure

Question 17

what is the the function of the adventitia

Answer 17

binds airway to the rest of the lung

Question 18

where does the smooth muscle sit in the dog, ox and horse?

Answer 18

dog - smooth muscle sits ontop of cartilage ring

ox & horse - smooth muse sis under cartilage ring

Question 19

do the bronchus (primary and secondary) and the segmental bronchi have cartilage?

Answer 19

interlocking and small plates of cartilage respectively.

Question 20

conducting and respiratory bronchioles do not have cartilage plates, how do they stop them from collapsing?

Answer 20

smooth muscle control - smooth muscle tone keep little more rigid
elastic fibres - “alveolar attachment” when lung expand, stretch fibres and pull on small airways keeping them open

Question 21

what are the various defence mechanisms of the respiratory system?

Answer 21

nasal hairs --> stop large particles
cough & sneeze reflex
lymphoid organs
luminal epithelium 
mucociliary clearance
specialised small airway cells - club cells
alveolar macrophages

Question 22

what are the defence mechanisms of the respiratory columnar epithelium?

Answer 22

boundary to the outside world
interact with immune cells
secrete cytokines and mediators –> support dendritic cell processes to sample the lumen

Question 23

describe the action and function of the mucociliary clearance

Answer 23

cilia on epithelium beat in one direction –> towards mouth
epitheium secrete water solution allowing cilia to beat
stop of water secretion = mucus secreted by goblet cells
traps foreign material w/ ciliary beating moved towards mouth for swallowing or to be coughed out

Question 24

what is cystic fibrosis?

Answer 24

mucociliary clearance doesn’t work

–> ion channels broken, no water secretion from epithelium –> mucus layer stuck and doesnt get expelled

Question 25

what is the role of club cells?

Answer 25

smaller airways have no mucus secretions –> they would clog up
detoxify toxins by metabolising them (engulf)
secrete IgA
secrete surfactant, decreasing surface tension

Question 26

what nerve innervates the sneezing reflex

Answer 26

trigeminal nerve - CN V

Question 27

how is the trigeminal nerve innervated to initiate the sneezing reflex?

Answer 27

brush cell receives irritant, CN V triggered

Question 28

describe anatomically what occurs during the sneezing reflex

Answer 28

• deep inspiration
• lung full of air
• closure of glottis
• forced contraction - internal intercostal and abd. muscle
• contraction, pushes against glottis
• forces air out through nose

Question 29

what nerve innervates the coughing reflex?

Answer 29

glossopharyngeal nerve - CN IX

Question 30

how is the glossopharyngeal nerve innervated to initiate the coughing reflex?

Answer 30

mechanoreceptors in trachea, larynx and bronchus detect foreign particle

Question 31

describe anatomically what occurs during the coughing reflex

Answer 31

• deep inspiration
• brief closure of glottis
• contraction of forced inspiratory muscles - internal intercostal and abd. muscle
• abrupt force of air directed through the mouth
• • cough can also be voluntary