Lecture 15 LRT

Question 1

what does the lower respiratory tract (LRT) consist of?

Answer 1

• Trachea
• Bronchi
• Bronchioles
• Alveoli

Question 2

whats the functions of the LRT?

Answer 2

conducts air to/from site of gas exchange

completes cleaning, warming, humidification of inhaled air

Question 3

where does gas exchange occur?

Answer 3

Alveolus (pl Alveoli)

Question 4

LRT: Trachea

where is it located?

Answer 4

• anterior to esophagus

* larynx to primary bronchus

Question 5

LRT: Trachea

whats it lined with?

Answer 5

respiratory mucosa

Question 6

LRT: Trachea

whats its functions?

Answer 6

Maintain patent (open) airway

Cleans, warms and humidifies inhaled air

Cilia -> mucociliary escalator (‘tracheal elevator’)

Question 7

LRT: Trachea

how does it Maintain patent (open) airway?

Answer 7

– “C”-shaped cartilage rings
– trachealis muscle
– CT with elastic fibres

Question 8

trachealis muscle

Answer 8

Trachea

Band of smooth muscle connect ends of a rings

• Contracts on coughing

Question 9

LRT: Trachea

how does it Cleans, warms and humidifies inhaled air?

Answer 9

– RS epithelium
• Mucous cells, ciliated cells
• Mucociliary escalator
– Glands

Question 10

Left bronchus

Answer 10

Narrower
Steeper angle
- blockages

Question 11

LRT: Bronchial Tree

what does it consist of?

Answer 11

• Trachea
• 1° bronchi
• 2° (lobar) bronchi
• 3° tertiary bronchus
• branching (tree like)
• alveolus

Question 12

LRT: Bronchial Tree

How many lobes does the right side have?

Answer 12

3

Question 13

LRT: Bronchial Tree

How many lobes does the left side have?

Answer 13

2

Question 14

1° Bronchi histology

Answer 14

– extra and intrapulmonary
– cartilaginous plates
– complete layer of smooth muscle

Question 15

3° bronchi histology

Answer 15

bronchopulmonary segments

branch

Question 16

bronchioles histology

Answer 16

<1mm, no cartilage

ring of smooth muscle

Question 17

As the bronchi decrease in diameter

Answer 17

– Cartilage – decreases
– Height of epithelium decreases
– Number of mucous secreting cells decrease

bronchioles – No cartilage

Question 18

If airborne debris gets to alveoli

Answer 18

– macrophages

Question 19

End of airway is the air sacs

Answer 19

alveoli

Question 20

alveoli

Answer 20

Arranged like bunches of grapes
Each lung around 150 million
- has large SA
- most of lung volume

Question 21

The walls of the alveoli are composed of

Answer 21

single layer of thin, flattened epithelial cells with a thin basement membrane (aka basal laminae).

Question 22

basal laminae

Answer 22

alveoli

single layer of thin, flattened epithelial cells with a thin basement membrane

Question 23

what are the external surfaces of the alveoli covered in?

Answer 23

pulmonary capillaries.

Question 24

LRT: Alveolus

whats the structure?

Answer 24

• pocket like - open at one side
• dense capillary network covering (cobweb basket)
• pneumocytes (lung epithelial cells)

Question 25

what are Type 1 pneumocytes?

Answer 25

squamous epithelial cells gas exchange scattered amongst type 1 are type 2 cells

Question 26

what are type 2 pneumocytes?

Answer 26

cuboidal surfactant secreting cells mix of phospholipids and proteins to decrease surface tension of alveolus

Question 27

LRT: Alveolus whats surfactant?

Answer 27

complex glycolipid / phospholipid that acts to reduce the surface tension of the alveolar fluid

Question 28

macrophage (dust cells)

Answer 28

release elastase | enzyme destroys elastin

Question 29

what makes up the blood air barrier?

Answer 29

surfactant coating alveolar surface alveolar cell layer fused basement membranes of alveolar epithelium and capillary endothelium capillary endothelium endothelial cell fused basement membrane type 1 epithelial cell

Question 30

lungs in thoracic cavity

Answer 30

breathing / ventilation | pleural cavity

Question 31

whats pleura?

Answer 31

serous membrane - parietal pleura - visceral pleura

Question 32

thoracic contents

Answer 32

``` Mediastinum (heart vessels, pericardium) Pleural cavities (lungs separate, if 1 not function got another 1) ```

Question 33

where does 1° bronchius vessels enter?

Answer 33

Hilum of lung

Question 34

LRT: | Difference between right and left lung

Answer 34

Right lung - 3 lobes (sup, middle, inf) - 2 fissures (horiz, oblique) Left lung - 2 lobes (sup, inf) - 1 fissure (oblique) - cardiac notch

Question 35

what makes up the left and right lungs? | medial view

Answer 35

``` Apex groove for aorta root of lung hilum base inferior surface on diaphragm = domed ```

Question 36

apex of lung is

Answer 36

superior region of lung

Question 37

coastal surface

Answer 37

outer surface against ribs

Question 38

base of lung is

Answer 38

inferior sits on diaphragm

Question 39

How are the trachea and primary bronchi held open so that they do not collapse?

Answer 39

by cartilage

Question 40

``` Which of the following structures does not have cartilage in its wall A. Intrapulmonary bronchus B. 2 ̊ bronchus C. trachea D. bronchiole E. Nasal septum ```

Answer 40

D. bronchiole

Question 41

Name the features of the mucous membrane that are very important in the gas exchange barrier

Answer 41

flattened type 1 pneumocytes sharing basement membrane. type 2 pneumocytes provide surfactant to keep the gas barrier moist and prevent sticking to the surface of other alveoli, strong basement membrane, elastic fibres near to help inspiratory recoil.