Module 7: The Respiratory System

Question 1

The respiratory system

Answer 1

Consists of the: nose, larynx, trachea, bronchial tree,and lungs
Critical for breathing in oxygen and breathing out carbon dioxide

Question 2

Respiration

Answer 2

Regwated by centers in the brain
A coordinated effort among the nostrils, lungs, intercostal muscles, diaphragm, and the heart

Question 3

Nostrils aka nares

Answer 3

The external openings through which the animal inhales and exhales air

Question 4

Functions of the nose

Answer 4

Filter air
Humidify air
Modify the temperature of inhaled air
Smell
Eliminate irritants and infections agents entering the nose by secreting mucous or serous (watery) secretions
Local immune response

Question 5

Nasal cavity: structure

Answer 5

Divided into 2 halves by a septum
Each half → 3-4 turbinate bones (turbinates aka concha)
Mucous membrane lines the turbinates and walls of the nasal cavity
Very back of nasal cavity has the ethmoturbinate

Question 6

Turbinates aka concha

Answer 6

Turbinate bones within each half of the nasal cavity that look like delicate scrolls
Lined by a mucous membrane along with the walls of the nasal cavity

Question 7

Ethmoturbinate

Answer 7

A special turbinate bone located at the very back of the nasal cavity
Lined with a specialized mucous membrane that has a large number of sensory neurons for olfaction (aka the sense of smell)

Question 8

The septum

Answer 8

Divides the 2 sides of the nasal cavity
Cartilaginous
Covered by the nasal mucosa
2 turbinates: dorsal and ventral

Question 9

Dorsal and ventral turbinates

Answer 9

The dog: the ventral turbinate is more elaborate than the dorsal turbinate
Larger species: both turbinates are equally elaborate
They divide the nasal cavity into 3 meati (aka channels or passages) → the dorsal, middle, and ventral nasal meatus

Question 10

Meatus (singular) → plural= meati (pronounced mee-yay-tie)

Answer 10

Means channel or passage
3 are seen in the nasal cavity due to its division by 2 turbinates = the dorsal nasal meatus, the middle nasal meatus, and the ventral nasal meatus

Question 11

Hard palate

Answer 11

Lies underneath the nasal cavity
Its core → made of the palatine process of the maxillary bone
Lined by oral mucosa on the ventral aspect and by the nasal mucosa on the dorsal aspect

Question 12

The nasal mucosa

Answer 12

Highly vascular
Contains cells that have cilia → help trap particulate matter and some organisms
Contains goblet cells that produce mucous
Has glands that secrete a serous fluid → keeps nasal cavity moist and humidifies air passing through

Question 13

The horse’s nasal structure

Answer 13

The nasal septum extends the whole length of the hard palate → thus, each nasal cavity communicates with the pharynx directly
The result = horses cannot vomit → if they do, they expel through their nostrils and it’s not a good sign

Question 14

Nasal structure in dogs and ruminants

Answer 14

The caudal portion of the nasal septum does not meet the hard palate
The hard palate is shorter and is followed by the soft palate
Thus, there’s only one common opening from the nasal cavity to the pharynx → In ruminants = this facilitates cud chewing

Question 15

Cud chewing (by ruminants)

Answer 15

The animal will regurgitate coarse food particles into the oral cavity, chew them into finer particles and swallow them once again

Question 16

The paranasal sinuses

Answer 16

Closely associated with the nasal cavities → they are diverticula of the nasal cavity that delve into the bones of the skull
They open into the nasal cavity either directly or indirectly → but the openings are small and narrow
Thus, blockages of these openings = congestion and is of clinical relevance

Question 17

Types of sinuses

Answer 17

Most species → both frontal and maxillary sinuses in each halfof the skull → the sinuses of the 2 sides don’t communicate with each other
Horses → maxillary sinuses are very elaborate
Bovine → frontal sinuses are very elaborate
Dog → instead of a distinct maxillary sinus, there’s a maxillary recess.

Question 18

Function of the sinuses

Answer 18

Still unclear
Believed they may provide protection, enlarge the surface area, provide resonance to the voice, etc.

Question 19

Larynx aka the voice box

Answer 19

Connects the pharynx to the trachea (through it to the lungs)
Situated below the pharynx and is connected to the base of the skull via a series of bones → the hyoid apparatus
Composed of cartilages → epiglottis, arytenoid, thyroid,and cricoid
Is covered by muscles

Question 20

Function of the larynx

Answer 20

Most important: to protect the lower portions of the respiratory tract from entry of food and water
This is achieved by a set of muscles associated with the larynx

Question 21

Trachea aka the wind pipe

Answer 21

Runs from the larynx and splits into 2 branches above the heart → the bronchi that enter the lungs
Innermost layer → lined by mucous membrane
Made of tracheal rings

Question 22

Tracheal rings

Answer 22

Form the fibro- cartilaginous part of the trachea
The rings = cartilaginous and incomplete → to facilitate expansion
Ends of the rings are connected by a smooth muscle → trachealis muscle

Question 23

Bronchi (plural) → bronchus (singular)

Answer 23

The 2 main branches that the trachea splits into above the heart
Bronchi divide into smaller branches = bronchioles

Question 24

Bronchioles

Answer 24

Finally terminate in the alveolar duct → into alveolar sacs → air exchange takes place
Tertiary bronchioles → end in alveoli → fill the surface of the lung

Question 25

Alveoli

Answer 25

Lined by a thin epithelium
Have lots of capillaries → to facilitate air exchange
Have specialized cells = pneumocytes

Question 26

The lungs: structure

Answer 26

Left and right lungs= very similar
Right lung is larger than the left lung
Lobation = number of lobes → of the lung → different among different domestic animal species
Lined by pleura, a serous membrane

Question 27

The dog’s lungs

Answer 27

The left lung → divided into: the cranial lobe, the middle lobe, and the caudal lobe
The right lung → additional lobe = the accessory lobe

Question 28

Pleura

Answer 28

A serous (watery) membrane that lines the lungs → also lines the corresponding area in the thoracic cavity
Visceral pleura aka pulmonary pleura = the pleura that lines the lungs
Diaphragmatic pleura= the pleura that lines the diaphragm
Costal pleura = the pleura that lines the ribs

Question 29

What happens to air during respiration?

Answer 29

Inhales air = is humidified and warmed by the nostrils
Passes through the pharynx into the larynx → trachea → bronchi → bronchioles → alveolar duct = reaches the alveoli
In the alveoli: Oxygen is transferred to the blood and carbon dioxide from the blood is transferred to the air
Air passes out the body in the same way = gets exhaled

Question 30

What happens to blood in respiration?

Answer 30

In the alveoli: Oxygen is transferred to the blood and carbon dioxide from the blood is transferred to the air
Pulmonary artery brings in unoxygenated blood to the lungs → gets oxygenated
Oxygenated blood travels via the pulmonary vein → reach the heart → pumps to it the rest of the body

Question 31

What happens if respiration stops?

Answer 31

The brain will lose its oxygen supply → thus, so will the other tissues
The heart may pump a little longer but will also eventually stop.