Respiratory Anatomy

Question 1

Upper respiratory tract

Answer 1

Nostrils, nasal cavity, pharynx, larynx

Question 2

Lower respiratory tract

Answer 2

trachea, lungs

Question 3

External nostrils

Answer 3

Externally covered by skin, cartilage on medial, dorsal and ventral surface. Margins of nostrils are mobile.

Question 4

Nasal cavity

Answer 4

Extends from external nostril -> internal nostrils (choanae) at caudal extremity of hard palate

Question 5

Nasal septum

Answer 5

median partition of nasal cavity = cartilage rostrally, bone caudally

Question 6

Concha (turbinate)

Answer 6

bony scroll protruding into nasal cavity - covered with mucosa. Defines the passageways for air = meatuses.

Question 7

Paranasal Sinuses

Answer 7

Air filled cavities the skull bones - arise from nasal cavity and retain very narrow connections with it

Question 8

Nasal cavity functions and histology

Answer 8

Nasal cavity modifies incoming air. Air warmed as it passes over vascular mucosa. Humidified by vaporization of tears and serous nasal secretions. Cleansed by contact with secretions from mucous glands - mucus moves towards pharynx and is swallowed. Mucosa has ‘typical respiratory epithelium’ - except olfactory area.

Question 9

Typical Respiratory Epithelium (TRE)

Answer 9

Ciliated, pseudostratified columnar epithelium with goblet cells. Lies on CT with numerous blood vessels and glands. Lines most of nose and respiratory tract.

Question 10

Pharynx

Answer 10

Common chamber of digestive and respiratory tracts

Question 11

Larynx

Answer 11

Connection between pharynx and trachea. Made of a number of individual cartilages, joined by ligaments, membranes and associated muscles.

Question 12

Function of Larynx

Answer 12

Regulation of airflow. Prevention of inspiration of food. Vocalization.

Question 13

Trachea

Answer 13

C-shaped cartilage rings interspersed with annular ligaments. Gap in rings closed by elastic connective tissue and trachealis muscle dorsally. Bifurcates into 2 bronchi dorsal to heart.

Question 14

Terminal bronchiole

Answer 14

last component of conducting airways (no gas exchange)

Question 15

Respiratory bronchiole

Answer 15

Smallest bronchiole. Connect conducting passages to primary structures involved in gas exchange between air and blood - outpouchings called alveoli.

Question 16

Alveolus

Answer 16

functional unit of lung. Single layer flattened epithelial cells. Form groups called alveolar sacs, which are the end of the respiratory tree. Gas exchange occurs readily across the thin fragile wall of the alveoli to capillaries on the external surface.

Question 17

Lung anatomy

Answer 17

Lungs - paired. Right lung > Left lung. soft organs - change in size and shape depending on stage of respiration. Subdivided into lobes according to divisions of bronchi (air supply).

Question 18

Hilus

Answer 18

site where structures enter or exit lung (bronchi, arteries, veins, nerves)

Question 19

Patterns of lobation

Answer 19

Left lung - cranial, caudal. Right lung - cranial, middle, caudal.

Question 20

Lobules

Answer 20

Internal subdivisions of lungs (lobulation). -> marbled surface appearance. The extent of lobation and lobulation can be used to differentiate lung tissue between species.

Question 21

Thoracic cavity

Answer 21

Space enclosed by ribs, vertebrae, sternum, diaphragm. Contains lungs in their pleural sacs + central mediastinum. Lungs and thoracic wall covered by Pulmonary pleura. Two pleural sacs. Maintains negative pressure. Each sac has a pleural cavity.

Question 22

Mediastinum

Answer 22

part of the thoracic cavity between the lungs: heart, esophagus, blood vessels, thymus, trachea.

Question 23

Pulmonary pleura

Answer 23

thin membrane of simple squamous epithelium and connective tissue

Question 24

Thoracic cavity - breathing

Answer 24

Lateral surfaces of lungs push against walls of thorax. Medial surfaces push against other thoracic organs.

Question 25

Steps of breathing

Answer 25

1. Inspiratory muscles contract
2. Thoracic cavity expands - Lateral surfaces of lungs push against walls or thorax - Medial surfaces push against other thoracic organs
3. Increase in negative pressure
4. Air flows into lungs until alveolar pressure equals atmospheric pressure