anatomy & histology of respiratory system

Question 1

What are the functions of the respiratory system?

Answer 1

* airflow - allow movement of air in and out of site of gaseous exchange
* **gas exchange and transport **of oxygen and CO2
* conditions air : warm, filter and humidify air
* temperature regulation
* immune protection - against microbes and foreign matter

Question 2

What is inspiration?

Answer 2

• the movement of air from the external environment into the alveoli

Question 3

what is expiration?

Answer 3

• the movement of air from the alevoli **to the external environment **

Question 4

Compare and contrast the conducting vs respiratory zone

Answer 4

1. Conducting zone - nasal cavity functions to get air in, moisten and clean air
2. respiratory zone - (alveoli) gas exchange

Question 5

how does air enter the nasal cavity?

Answer 5

through 2 nostrils

Question 6

what is the pharynx?

Answer 6

• passageway that connects the nasal and oral cavity

Question 7

what are the** functions of the larynx**?

Answer 7

• maintains open passageway for** air movement **
• prevents swallowed materials from entering the trachea
• sound production

Question 8

Describe the branching of the respiratory tract

hint: what are the 2 main zones? start from trachea

Answer 8

1. Conducting zone
   * the trachea branches into the left and right bronchi
   * the bronchi branches into** bronchioles** which then split into terminal bronchioles **
   2. Respiratory zone**
   * terminal bronchioles branch into **respiratory bronchioles **
   * respiratory bronchioles branch into alveolar ducts which then branch into alveolar sacs

Question 9

what is the** function** of the trachea?

Answer 9

• warm, clean & conduct air

Question 10

What is present in the mucosa of the trachea?

Answer 10

• respiratory epithelium (pseudostratified ciliated tall columar cells )
• goblet cells
• serous cells
• basal cells
• brush cells
• basement membrane

Question 11

what glands does the submucosa of the trachea contain?

Answer 11

seromucous glands (mixed)

Question 12

What type of cartilage is present in the trachea and what is it’s** function**?

Answer 12

• C shaped hyaline cartilage
• function : allows trachea to maintain an open position, providing respiratory support

Question 13

What is the smooth muscle in the trachea called & what happens when it contracts?

Answer 13

trachealis muscle
* contraction of this muscle **reduces the diameter **

Question 14

How is the basic structure of the bronchus different to the trachea?

Answer 14

• respiratory epithelium is **less tall with fewer goblet cells **
• the lamina propia has** more elastin fibres** and is separated from the submucosa
  * smooth muscle becomes more prominent in distal bronchi
• submucosa has less seromucous glands
• cartilage is flattened interconnected plates rather than distinct rings

Question 15

Describe the structure of bronchioles (in comparison to bronchus)

Answer 15

• no cartilage!
• no submucosal glands !
• few goblet cells
• ciliated columnar epithelium which later becomes squamous

Question 16

what elements of the lower respiratory tract are in the respiratory zone?

Answer 16

• respiratory bronchioles
• alveolar ducts
• alveolar sac’s
• alveoli

Question 17

what do respiratory bronchioles divide into?

Answer 17

• they divide into several alverolar ducts (AD) which have several alveoli
• the alveolar ducts end in an alveolar sac which in turn opens to several alveoli

Question 18

Describe alveoli

Answer 18

• aprrox 300 mill air sacs
• very **large surface area **
• 1 cell thick
• surrounded by capillaries
• alveolar pores (of Kohn) (discrete holes between adjacent alveoli) which allow some movement of air between alveoli

Question 19

what are the alveolar pores of Kohn and what is their function?

Answer 19

• discrete holes in the walls of alveoli
• they allow the movement of air between adjacent alveoli

Question 20

what does the alveolar wall consist of?

Answer 20

• surface epithelium
• supporting tissue
• **blood vessel **
• Type I pneumocytes (alveolar lining cells)
  * Type II pneumocytes P2
• capillaries with red blood cells
• alveolar** macrophages **

Question 21

what is the function of alveolar macrophages?

Answer 21

• phagocytic cell
• contributes to immunity

Question 22

What are type I pneumocytes & function?

Answer 22

• large flattened cells
• 95% surface area of alveoli
• facilitate gas exchange
• communicate with type II cells

Question 23

What are type II pneumocytes and function?

Answer 23

• these cells** produce and secrete pulmonary surfactant **( which prevents alveolar collapse)
• they can regenerate alveoli after injury

Question 24

what is the pleura?

Answer 24

• the pulmonary pleura are 2 opposing layers of serous membrane overlying the lungs and inside of the surrounding chest walls

Question 25

what are the** 2 layers** of the pleura?

Answer 25

• parietal pleura - forms the internal lining of the chest cavity
• visceral pleura - externally coats the lung