Respiratory System

Question 1

what does the respiratory system consist of?

Answer 1

the lungs and a series of airways that connect the llungs to the external enviroment

Question 2

what are the two major subdivisions of the functional respiratory system?

Answer 2

1. conductance portion - airways that deliver air to the lungs
2. respiratory portion - structures in which oxygen in the inspired air is exchanged for carbon dioxide in the blood

Question 3

what is the characteristics of the trachea?

Answer 3

the walls are supported by C-shaped cartilages, whose open ends face posteriorly. smooth muscle extends between the open ends.

dense fibroelastic connective tissue is located between the adjacent cartilage rings, which permit elongation of the trachea during inhalation.

Question 4

in the mucosa of the trachae, what cells make up the epithelium lining?

Answer 4

1. ciliated cells
2. mature goblet cells
3. small mucous granule cells
4. DNES cells
5. short (basal) cells

Question 5

what is the composition of the wall of the trachea?

Answer 5

from the trachae lumen:

• mucosa
  - epithelium
  - basement membrane
  - lamina propria
• submucosa
• adventitia

Question 6

what does the submucosa of the trachae contain?

Answer 6

seromucous glands

Question 7

what is the adventitia of the trachae contain?

Answer 7

adventitia contains C-shaped rings of hyaline cartilage and forms the outermost layer of the trachae.

Question 8

what are secondary bronchi?

• arise from
• divide to
• lined by

Answer 8

secondary bronchi arise from primary bronchi that are derived from the trachae.

they divide many times to give lobular and then segmental bronchi

their walls contain irregular cartilage
they are lined by respiratory epithelium

spiralling bundles of smooth muscle separate the lamina propria from the submucosa, which contain seromucous glands

Question 9

what is respiratory epithelium?

Answer 9

respiratory epithelium is

pseudostratified ciliated columnar epithelium with goblet cells

Question 10

what are the characteristics of primary bronchioles?

Answer 10

primary bronchioles lack cartilage (smooth muscle instead) and glands in the submucosa.

they have a diameter of 1mm or less

larger airways lined by ciliated columnar with goblet cells
smaller passages lined by ciliated cuboidal with Clara cells

divide to form several reminal bronchioles after entering pulmonary lobules

Question 11

what are the characteristics of terminal bronchioles?

Answer 11

like the primary bronchioles they arise from, they lack cartilage and glands in the submucosa.

they are less that 0.5mm in diamter

they are lines by simple cuboidal epithelium, consisting mainly of clara cells, some ciliated cells and NO goblet cells.

Question 12

where are clara cells found and what are the functions of Clara cells?

Answer 12

clara cells are found in the primary bronchioles, more numerous in the terminal and respiratory bronchioles.

functions:

1. metabolise airborne toxins - in their abundant SER
2. secrete GAGs
3. divide to form ciliated cells

Question 13

what does the respiratory portion of the respiratory system involve?

Answer 13

respiratory portion include:

the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli, all in the lung.

Question 14

what are the characteristics of the respiratory bronchioles?

Answer 14

the respiratory bronchioles mark the transition from the conducting to the respiratory protion of the respiratory system.

they are lined by simple cuboidal epithelium, contain mostly Clara cells, except where their walls are interrupted by alveoli (gas exchange sites) where the lining abruptly changes to a simple epithelium composed of highly attenuated squamous cells.

Question 15

what are alveoli?

Answer 15

alveoli are pouchlike evaginations about 200um in diameter in the walls of respiratory bronchioles, in alveolar ducts and in alveolar sacs.

they have thin walls, across which O2 and CO2 diffuses between the air and the blood.

they are separated from each other by interalveolar septa.

they are lined by a highly attenuated simple squamous epithelium composed of type I and type II pneumocytes.

Question 16

what are the alveolar cells? (3)

Answer 16

type I pneumocytes
type II pneumocytes
alveolar macrophages (dust cells)

Question 17

what is the major difference between type I and type II pneumocytes?

Answer 17

type I cover 95% of the alveolar surface, with thin cytoplasm and CANNOT divide.

type II sulge into the alveolus, can divide and regenerate both types, and synthesise pulmonary surfactant.

Question 18

what is pulmonary surfactant?

Answer 18

surfactant is secreted by type II pneumocytes in the alveoli.
they consist of phospholipids and 4 proteins.
when released it spreads to produce a monomolecular film over the alveolar surface.

the function of surfactant permits the alveoli to expand easily during inspiration and stops collapse during expiration.

Question 19

what are alveolar macrophages?

- location
- function

Answer 19

alveolar macrophages or dust cells, are found in the alveoli. they are the principle mononuclear phagocytes of the alveolar surface.

they remove inhaled dust, bacteria and other particulate matter trapped in the pulmonary surfactant.

they migrate to the bronchioles after filling with debris. carried by via ciliary action to the upper airways, where they are swallowed or expectorated.