12/1 Upper Resp. Passageways- Structural/Functional Considerations

Question 1

Describe the concept of aerodynamic reach.

Answer 1

When a dog breathes in, it can tell which nostril the odor is coming into because each nostril’s aerodynamic reach is so small.

Question 2

What is the respiratory system lined with?

Answer 2

Respiratory epithelium (except ethmoidal conchae)

Question 3

What is respiratory epithelium made up of and what is the function of each component?

Answer 3

Goblet cells and sub-mucosal glands:
- Produce mucus that traps particulate matter
Cilis lines cells:
- Moves mucus towards pharynx
Serous glands:
- moisten inhaled air
Highly vascular lamina propria:
- warms air
- erectile tissue (can swell and go back down)

Question 4

What type of cells makes up respiratory epithelium?

Answer 4

Pseudostratified columnar ciliated epithelium with goblet cells

Question 5

What cells/glands exist in the ethmoidial conchae?

Answer 5

Olfactory epithelium:

• olfactory receptor cells
• bowman’s glands: secretion solubilises odors so they can be picked up by receptors
• supporting cells
• basal cells (stem cells)

Question 6

What is the vomeronasal organ?

Answer 6

Special olfactory mucosa located in ventral nasal meatus, either side of nasal septum

Function: chemoreceptor of liquid-borne compounds (picking up chemicals in urine etc)
–> Flehmen reaction

Question 7

What is special about equine breathing?

Answer 7

Obligate nasal breathers

Question 8

What characteristics help horses when breathing demand increases?

Answer 8

Nostril dilation
Constriction of blood vessels in nasal cavity
Larynx (glottis- abduction) opens up
Muscles of respiration

Question 9

What is special about the equine nasal vestibule?

Answer 9

Doesn’t communicate directly with nasal cavity

Nasal diverticulum:

• blind end pouch extends caudally to nasoincisive notch
• clinically relevant in passing stomach tubes/cameras

Question 10

What are some of the comparative difference of the nasal cavity between animals?

Answer 10

Ruminants + Equine:
- dorsal and ventral nasal conchae form sinuses at 4th-5th cheek teeth

Mucosa respiratory epithelium very vascular in equines (blood volume alters width of airways)

Pig:
- middle + ethmoidal conchae less developed

Question 11

What is the nose like in sheep and goats?

Answer 11

Called nasal planum:

• narrow
• philtrum (division) extends and divided upper lip
• skin hairless but glandular

Question 12

What is the nose of a cow like?

Answer 12

Nasolabial plate:

• planum fused with upper lips
• no philtrum
• long, tactile hairs

Question 13

What is the nose like in a pig?

Answer 13

Snout or Rostral plate:

• fused with upper lip
• contain rostral bones (strengthing, rooting)
• skin hairless, glandular

Question 14

What is special about ruminant nasopharynx?

Answer 14

Pharyngeal septum partially divides nasopharynx

- caudal edge of pharyngeal septum= pharyngeal tonsil