Respiration: Non-Respiratory Fx Of The Lung

Front 1

facts

Back 1

- airways and alveoli present a large area for gas exchange
- respiration continuously exposed airways to potentially harmful substances
- variety of defense mechanisms

Front 2

potentially hazardous substances

Back 2

1. solid particles: various sizes, dust, food, smoke
2. aerosols: fluid particles in air, oil-air
3. gases: ammonia, oxides of nitrogen, fuel fumes
4. biological agents: pollen, spores
5. infectious agents: bacteria, viruses, fungi

Front 3

mechanism of particle deposition

Back 3

- location of deposition depends on particle size
- >5microm: bends of larger airways
- 1-5 microm: sedimentation onto the walls of smaller airways
- <1microm: peripheral airways, diffusion to surface or exhaled again

Front 4

excretion of solid particles

Back 4

1. mucociliar escalator: particles entrapped in the mucous layer on top of the ciliated epithelium transported to the pharynx and swallowed
2. more hazardous, irritating mucous: cleared by coughing
3. injured epithelia become hyper-responsive: eg viral infection--> damage of epithelium --> coughing

Front 5

macrophages

Back 5

- first line of defense
- 85% cells in liquid layer lining the alveoli are macrophages
- phagocytize particles and microorganisms
- complement, osponins and lysozyme contribute to the destruction of microorganisms
- messengers to lymphoid tissues: critical role in immune system activation

Front 6

large particles

Back 6

- eg soot, cigarette smoke
- too large for mucociliar escalator
- moved into interstitium and deposited
- chronic exposure: destruction and reduced fx of mucociliar epithelium which contributes to inability to remove these agents

Front 7

very large particles

Back 7

- inspired food
- too big for transport to the pharynx
- enveloped by CT and remain

Front 8

deposition of toxic gases and aerosols

Back 8

determined by [] and solubility:
1. highly soluble gases in low []: SO2, entrapped in upper airways (nose, pharynx)
2. less soluble gases or higher concentrated gases: penetrate deeper into lungs, may reach alveoli

Front 9

toxic gasses: protective mechanisms

Back 9

1. bronchospasm
2. mucous hypersecretion
3. cough
4. sneeze

Front 10

metabolic fx of capillary bed

Back 10

- all blood returning from systemic circulation flows through lung
- large surface area
- ideal place for cleansing blood of agents produced or released by other body tissues

Front 11

vasoactive substances

Back 11

1. serotonin: cleared almost totally
2. NorEpi: cleared to some degree
3. bradykinin: inactivated by angiotensin-converting enzyme
4. angiotensin I: converted to a II
5. prostaglandins: majority degraded in lung

Front 12

ACH, Epi and histamine

Back 12

not removed

Front 13

leukotrienes

Back 13

degraded by neutrophils

Front 14

exogenous toxic substances

Back 14

removed from blood