Respiratory system

Question 1

Hila/lung roots

Answer 1

Complicated structures consisting of bronchi and pulmonary arteries and veins

Question 2

hilum of lungs

Answer 2

• Location where bronchioles enter the lungs
• the large triangular depression where the connection between the parietal pleura (covering the rib cage) and the visceral pleura (covering the lung) is made

Question 3

root of lung

Answer 3

Enters at hilum. Where structures enter and leave the lung

Question 4

Conducting portion

Answer 4

Structure: varying levels of wall thickness.
Location: portions inside (bronchi, bronchioles, terminal broncioles) and outside (nasal cavity to extrapulmonary bronchi) lung. Terminal bronchiole marks end of conducting zone.
Function: conduct and condition (filter, heat, humidify)

Question 5

Respiratory portion

Answer 5

structure: thin walled for efficient gas exchange
location: only in lungs. Respiratory bronchioles and alveolar ducts and sacs.
function: gas exchange

Question 6

Bronchial circulation

Answer 6

• nutrient arteries
• bronchial arteries are branches of aorta
• provide nourishment for CT, walls of bronchi and brionchioles and pleura

Question 7

Pulmonary arteries

Answer 7

• carry deoxygenated blood from right side of heart

- travel with branches of bronchi and bronchioles down to capillary level

Question 8

Pulmonary veins

Answer 8

• oxygenated blood carried from capillary level to venules to four veins that go to left atrium
• do NOT run with pulmonary artery
• located in CT segments of lung

Question 9

Pulmonary capillary bed

Answer 9

• largest capillary bed in body

- strictly continuous capillaries (tight junctions only)

Question 10

Respiratory cartilage

Answer 10

• hyaline cartilage
• C-shaped rings in trachea (open on posterior surface)
• plates in bronchi become progressively smaller down the respiratory system.

Question 11

Respiratory smooth muscle

Answer 11

regulates diameter of airway

-gone at level of alveolar duct

Question 12

Collagen and elastic fibers in respiratory system

Answer 12

• together form network that allow expansion/recoil of lung

- extracellular proteins secreted by fibroblasts that play a major role in lung physiology

Question 13

Emphysema

Answer 13

• enlargement of airspace distal to terminal bronciole and destruction of walls without fibrosis (lowers surface area)
• COPD (chronic obstructive pulmonary disease)
• enzymatic degredation of elastin
• caused mostly by cigarette smoking

Question 14

pleura (serous membrane)

Answer 14

mesothelium and CT underlay

two major types:

1: parietal pleura associated with walls of body cavity
2: visceral pleura which adheres to and covers surface of lung

Question 15

Turbinates or Conchae

Answer 15

Structure: bony shelf like projections lined with pseudostratified epithelium; well vascularized. 3 nasal concha
Function: increase surface area and create turbulent airflow
Location:lateral walls of nasal cavities

Question 16

Trachea layers (3)

Answer 16

• mucosa (elastic rich lamina propria, no muscularis mucosae)
• submucosa
• adventitia/cartilage

Question 17

longitudinal folds

Answer 17

• seen in trachea and major bronchi

- formed by elastic fibers

Question 18

5 types tracheal epithelium

Answer 18

ciliated cells (most common), mucous cells, brush cells, small granule cells, basal cells

Question 19

Ciliated cells (in tracheal epithelium)

Answer 19

• maintain level of pericilary fluid (layer of water and electrolytes)
• 250 cilia per cell that provide coordinated sweeping motion
• forms mucocilary escalator
• clears mucous coat

Question 20

mucous cells (in tracheal epithelium)

Answer 20

• mucinogen granules in cytoplasm
• mucus floats on a serous fluid (perciliary fluid)
• cilia moves both serous and mucus toward the oral cavity

Question 21

brush cells

Answer 21

• columnar cells with blunt microvilli
• basal surface in synaptic contact with afferent nerve ending
• receptor cell

Question 22

small granule cells

Answer 22

AKA enteroendocrine cells

• contain secretory granules
• may function in reflexes

Question 23

basal cell

Answer 23

-stem cell for individual cell replacement in epithelium

Question 24

metaplasia

Answer 24

change from one epithelium type to another in response to an irritant

Question 25

Process of metaplasia in respiratory system

Answer 25

- pseudostratified respiratory epithelium changes to stratified squamous non keratinized epithelium - removal of mucous impaired - excessive mucous secretions in the lumen of repiratory tree - marked increase in size of the mucus secreting glands of the submucosa in the trachea and the large bronchi - must cough to clear secretions

Question 26

layers in wall of bronchus (4)

Answer 26

- mucosa: same epithelium and cells as trachea - muscularis: regulates diameter of airway - submucosa: glands present - adventitia/cartilage: plates smaller with decreasing diameter

Question 27

Intrapulonary bronchus

Answer 27

- has plates of cartilage instead of rings - layer of smooth muscle, the muscularis found below the mucosa layer - increase in elastic fibers

Question 28

bronchioles

Answer 28

- airways 1mm or less - in CT of lung, so diameter increases and decreases with lung volume - includes terminal and respiratory bronchiles - pseudostratified to simple columnar to simple cuboidal epithelium - gradual changes

Question 29

terminal vs respiratory bronchioles

Answer 29

Terminal: non-respiratory in conducting airways, smallest most distal part of the conducting portion, epithelium has club cells and some ciliated cuboidal cells. Respiratory: first region where gas exchange occurs, wall is interrupted with alveoli, club cells and some cilia cells (club cells dominate)

Question 30

Changes at level of bronchioles

Answer 30

- bronchioles lack cartilage - bronchiole lack submucosal glands - thick layer of smooth muscle is present - simple cuboidal epithelium: ciliated cells decreasein number and club cells increase when proceeding to respiratory zone

Question 31

Club cells (Clara cells)

Answer 31

Structure: simple columnar, nonciliated, dome shaped apical aspect projects into lumen Function: Detoxify harmful compounds in the air, secrete a lipoprotein that prevents luminal adhesion, mitotically active stem cell Location: bronchioles

Question 32

Alveoli

Answer 32

- site of gas exchange - lined type I and II pneumocytes, occasional brush cells - Type I and II pneumocytes most important epithelial cells in epithelium of alveolus

Question 33

Alveolar ducts

Answer 33

- smooth muscle disappears at the end of the duct | - elastic and collagen fibers are only support for alveoli

Question 34

Alveolar sacs

Answer 34

-spaces surrounded by clusters of alveoli

Question 35

Type I pneumocytes

Answer 35

Structure: squamous, attenuated cells, many of the organelles are clustered around nucleus leaving cytoplasm free for gas exchange. Very thin and streched. Function: provide barrier of minimal thickness that is optimal for gas exchange Location: occupies 95% of the surface area of the alveolus

Question 36

Type II pneumocytes

Answer 36

AKA septal cells Structure: rounded cells, apical cytoplasm contains lamellar bodies Location: typically found in corners and occupy 5% of the surface area Function: 1) undergo mitosis to regenerate themselves and type I pneumocytes. 2)continuously produce surfactant to prevent collapse of alveoli

Question 37

Interalveolar septum (thin region)

Answer 37

- wall between air sacs - site of air-blood barrier - houses capillaries that function in gas exchange - no CT - only type I pneumocyte

Question 38

Interalveolar septum (thick portion)

Answer 38

-Composed of collagen fibers, elastic fibers, capillaries, lymphatic vessels, fibroblasts, mast cells, alveolar macrophages.

Question 39

Blood-air barrier (respiratory membrane)

Answer 39

Four components: layer of surfactant, alveolar epithelium (type I pneumocyte cytoplasm), fused basement membranes of the alveolar cell and the endothelial cell, endothelial cell -all type I and type II pneumocytes have desmosomes and occlusing junctions

Question 40

Alveolar pores

Answer 40

AKA pores of Kohn - Function: equalizes pressures in the alveoli, enable collateral ventilation, allow macrophage migration - type II pneumocytes seen at thick portions like junctions

Question 41

defense mechanisms

Answer 41

- nose and trachea - mucociliary escalator (transport) - alveolar macrophages (dust cells)

Question 42

Mucociliary escalator

Answer 42

- traps and removes debris, bacteria, and particles. Moves particles and toxic substances from distal to proximal - components: cilia, serous fluid (periciliary fluid), mucous layer (produced by mucous cells and submucousal layers), alveolar macrophages

Question 43

Alveolar macrophages

Answer 43

- function in CT and airspaces of alveoli - some pass up the bronchial tree in mucus to reach the pharynx - some migrate to CT where they may stay with particles for the life of the individual (can cause blocked lung)