Histology Respiratory System Ii

Front 1

General characteristics of the bronchioles:

Back 1

- 1mm or less in diameter
- NO cartilage in their walls
- smooth muscle replaces the cartilage plates
- NO glands

Front 2

What lines the bronchioles?

Back 2

Epithelium varies from ciliated columnar with goblet cells ( in primary bronchioles) to ciliated cuboidal with secretory (Clara) cells (in terminal and respiratory bronchioles)
*Goblet cells only in larger bronchiole

Front 3

Intra-pulmonary conducting division of the respiratory tract can be divided into 3 regions:

Back 3

secondary bronchi
bronchioles
terminal bronchiole

Front 4

Terminal bronchiole is supported by:

Back 4

Smooth muscle

Front 5

Glands found within the terminal bronchiole?

Back 5

NO glands!

Front 6

What lines the terminal bronchiole?

Back 6

simple cuboidal consisting of Clara (secretory) cells and ciliated cells
*HAS SOME cilia
*NO goblet cells

Front 7

What does Clara cells contain?

Back 7

- abundance of SER (whose enzymes may be involved in metabolizing toxins from the inspired air)

Front 8

Features of the terminal bronchiole?

Back 8

less than 0.5 mm in diameter
Clara cells = Club cells

Front 9

Back 9

Terminal Bronchiole
*No cartilage (not Bronchi)
*No Goblet cells (not primary bronchiole)

Front 10

Location of the terminal bronchiole within the respiratory system:

Back 10

It is the most distal part of the conducting portion

Front 11

This is a slide of:

Back 11

Terminal bronchiole

Front 12

Is cartilage present within the terminal bronchiole?

Back 12

NO!
has an incomplete ring of smooth muscle

Front 13

The red arrow is pointing to?

Back 13

Clara cells = Club cells
- dome-like structure

Front 14

What does Club cells/ Clara cells produce?

Back 14

1. surfactant-like substance
2. cytochrome P450 enzymes
3. stem cell-like activity

Front 15

Respiratory bronchiole marks the transition between:

Back 15

conducting and respiratory portion of the system

Front 16

What is the function of the Respiratory bronchiole?

Back 16

It is the first portion of pulmonary tree in which gaseous exchange takes place

Front 17

What lines the respiratory bronchiole?

Back 17

simple cuboidal epithelium consisting of Clara cells and ciliated cells

Front 18

Respiratory portion of the pulmonary tree includes:

Back 18

Three regions:
1. Respiratory bronchiole
2. Alveolar duct
3. Alveolus

Front 19

Are there any glands within the respiratory portion?

Back 19

NO!

Front 20

What lines the alveolar duct?

Back 20

Simple squamous
*NO cilia
*No goblet cells

Front 21

Features of the Alveolar duct:

Back 21

Outpocketings of alveoli
type I pneumocytes
type II pneumocytes
dust cells (= macrophages)

Front 22

What lines the Alveolus?

Back 22

Simple squamous
*NO cilia
*NO goblet cells

Front 23

Features of the alveolus:

Back 23

Type I pneumocytes
Type II pneumocytes
dust cells (=macrophages)

Front 24

Identify structures and different regions.

Back 24

Terminal bronchiole (thicker with smooth muscles) dividing into 2 respiratory bronchioles, in which alveoli appear
- sponge-like appearance of the lung is due to the abundance of alveoli and alveolar sacs

Front 25

Red circles indicate?

Back 25

smooth muscles of the alveolar duct
- respiratory bronchiole is situated to the right of the alveolars (A)

Front 26

Back 26

smooth muscles are present throughout the structure but is thicker in the terminal bronchiole

Front 27

Alveolar duct is continuous with...

Back 27

the respiratory bronchiole

Front 28

Wall of alveolar duct consists of closely spaced alveoli that are separated from one another by:

Back 28

Interalveolar septum
*smooth muscle is present in the septum at the opening of adjacent alveoli
* Alveolar duct is most distal portion of the respiratory system to contain smooth muscle in its wall

Front 29

Structure of the respiratory bronchiole

Back 29

Front 30

Last portion of the bronchial tree that contains smooth muscle?

Back 30

Alveolar duct

Front 31

Characteristics of Alveolar sac?

Back 31

An expanded irregular space at the distal end of an alveolar duct
wall consists of adjacent alveoli

Front 32

Importance of the Alveoli?

Back 32

*Permits gaseous exchange between air and blood (oxygen from air to blood, and carbon dioxide from blood to air)

Front 33

Communication between alveoli occurs via?

Back 33

Alveolar pores (of Kohn)

Front 34

Structures of the alveoli?

Back 34

Rims of the openings into alveoli contain elastic fibers and supportive reticular fibers

Front 35

Epithelium lining the alveoli are composed of which 3 types of cells?

Back 35

Simple squamous epithelium composed of:
1. Type I pneumocyte
2. Type II pneumocyte
3. Alveolar Macrophage

Front 36

Characteristics of Type I pneumcoyte:

Back 36

- forms part of the blood-gas barrier
- has an extremely thin cytoplasm (< 80 nm thick)
- type I alveolar cell covers about 95% of alveolar surface
- tight junctions with neighboring cells

Front 37

Back 37

Slide of aliveoli and interalveolar septum
Type I (red circle)
Type II (blue circle)
alveolar spaces (clear spaces)

Front 38

Structure of type II pneumocyte:

Back 38

- bulging free surface contains short microvilli that are located peripherally
- (Type II alveolar cell, great alveolar cell, granular pneumocyte, septal cell) is low cuboidal and is located most often near septal intersections
- tight junctions between neighboring cells

Front 39

What does Type II pneumocytes do?

Back 39

- release of surfactant from the lamellar bodies produces a monomolecular film that spreads over the alveolar surface
- synthesizes pulmonary surfactant which is stores in lamellar bodies in its cytoplasm
- able to divide and regenerate both cell types in the alveolar epithelium

Front 40

What are the bload arrows pointing to?

Back 40

EM of a type II cell
- Lamellar bodies (BLE arrow) containing newly synthesized pulmonary surfactant
- note Junctional complexes (JC), microvilli

Front 41

What are the alveolar macrophages?

Back 41

(Dust cell, alveolar phagocyte)
=principal mononuclear phagocyte of the alveolar surface

Front 42

Function of the alveolar macrophages:

Back 42

removes inhaled dust, bacteria and other particulate matter
= vital line of defense in the lung

Front 43

Exit route of alveolar macrophages:

Back 43

1. when filled with debris, it migrates to the bronchioles and is carried via ciliary action to the upper airways and pharynx, where it is swallowed
2. migrate into interstitium and leave via lymphatics

Front 44

Back 44

(LEFT): alveolar macrophage of a Non-smoker; numerous small lysosomes are present
(RIGHT): Alveolar macrophage of a Smoker; cytoplasm is crowded with pigment masses = undigestible residues of material phagocytized from the alveoli

Front 45

Identify structures in this EM.

Back 45

Front 46

A thin Interalveolar septum is important for:

Back 46

Providing efficient gaseous exchange between blood and air

Front 47

Characteristics of the interalveolar septum:

Back 47

- septum = wall, or partition between two alveoli
- continuous capillaries occupy its central (interior) region
- elastin and reticular fibers are present in some of the thicker regions of the septal wall
- elsewhere the septum constitutes the site of the blood-gas barrier

Front 48

What lines the interalveolar septum?

Back 48

an attenuated (=thin) simple squamous epithelium

Front 49

What is the blood-gas barrier?

Back 49

it is the barrier to diffusion of gases between the alveolar air and the blood

Front 50

In the thinnest areas of the blood-bas barrier, it consists of:

Back 50

1. layer of surfactant
2. thin epithelium of the type 1 pneumocyte
3. fused basal laminae of the type I pneumocyte and capillary endothelium
4. endothelium of the continuous capillary

Front 51

Average distance across the blood-gas barrier:

Back 51

~0.5 µm

in areas where the 2 basal lamina fuse, to eliminate the thin interstitial space, the distance across the barrier is reduced to 0.2 µm or less

Front 52

Vascular supply of lungs:

Back 52

Pulmonary artery

Front 53

Pulmonary artery:

Back 53

- carries blood to the lungs to be oxygenated
- enters the root of each lung and extends branches along the divisions of the bronchial tree

Front 54

Pulmonary veins:

Back 54

- Run independently of the arteries in the intersegmental CT
- after leaving the lobules of the lung the veins come into close association with branches of the bronchial tree
- from this point to the root of the lung the veins accompany the bronchi

Front 55

Branches of the pulmonary artery and veins follow...

Back 55

branches of the bronchial tree, except within the lobules, where only arteries follow the bronchioles

Front 56

Pulmonary artery carries (oxygenated / deoxygenated) blood?

Back 56

DEOXYgenated

Front 57

Pulmonary vein carries (oxygenated / deoxygenated) blood?

Back 57

OXYgenated

Front 58

learn all structures

Back 58

.

Front 59

What does this slide show?

Back 59

Alveolar capillary network

Front 60

Characteristics of lung lobules:

Back 60

- Each bronchiole that arises from a bronchus enters what is known as a lung lobule
- an incomplete septum separates each lobule from its neighbor
- lymphatics run within the dense connective tissue but are not present within the interalveolar wall

Front 61

Shape of the lobules:

Back 61

~pyramid
has an apex and a base
varies greatly in size and shape
- an incomplete septum separates each lobule from its neighbor

Front 62

Nerve innervation to smooth muscle of bronchi and bronchioles are:

Back 62

By both divisions of the autonomic nervous system
- Axons are within thicker parts of the interalveolar septa

Front 63

Lung characteristics during breathing:

Back 63

- During inspiration, the thoracic cage enlarges, becoming deeper wider and longer
- lung has large amount of elastic tissue, which permits extensive expansion and relaxation
- Each lung is enclosed in a pleural sac and the pleural space is under negative pressure

Front 64

As thoracic wall increases in size, the visceral pleura which is firmly attached to the lung is also drawn outward, what happens to the pressure within the lungs when this happens?

Back 64

Air pressure within the lungs DECREASES and air is drawn INTO them

Front 65

Expel of air is done by:

Back 65

elastic recoil of the lungs, which decreases the thoracic cage to its initial size