Respiratory System PDF

Respiratory Sysem By Dr. Fatma yassine  Divisions of respiratory system The conducting system : conducting, filtering and conditioning inspired air before reaching lung The respiratory portion : exchange of gases  The trachea The trachea is...

Respiratory Sysem By Dr. Fatma yassine  Divisions of respiratory system The conducting system : conducting, filtering and conditioning inspired air before reaching lung The respiratory portion : exchange of gases  The trachea The trachea is about 12 cm long from Larynx above and bifurcate into two bronchi in the lower end kept patent with 20 C shaped incomplete rings of hyaline cartilage  Microscopic structure of the trachea 1- Mucosa (epithelium & Lamina propria) Epithelium : Psaudostratified columnar ciliated with goblet cells. Goblet cells for mucus secrection Cilia move up dust particles Lamina p.ropria: C.T rich in elastic fibers Secretion and transportation  Microscopic structure of the trachea 2- Submucosa C.T with mixed gland (mucoserous) glands Elastic membrane separating it from lamina propria  Microscopic structure of the trachea 3-The fibrocartilagenous layer: C.T with incomplete C shaped hyaline cartilage deficient posteriorly towards the esophagus Smooth muscles fibers between the cartilage ends  The extrapulmonary Lung bronchus are similar in structue to trachea The right lung : 3 lobes The left lung: 2 lobes  Microscopic structure of the Lung The intrapulmonary bronchus: 1-Mucosa: folded 2- Submucosa: Continuous thin sheath of smooth muscle. 3-Fibrocartilagenous layer: multiple plates of cartilage& glands  The bronchioles 1- Mucosa: large bronchioles S.Col.cil.ep with goblet cells and some non ciliated (Clara cells) in small one S.Cupoidal cil.with few Clara cells no goblet cells. 2- Muscle layer: well developed SM layer 3- C.T layer: no cartilage or glands  Respiratory bronchiole Lined with cuboidal cells Numerous alveoli open into it and few alveoli open into them  Alveoli Polyhedral sacs with one wall deficient Lined with alveolar epithelium. Separated by inter alveolar septa. The interalveolar septum: It is a C.T. containing elastic fibers, reticular fibers and pulmonary alveolar phagocytic cells as well as blood capillaries.  Alveolar epithelium Type 1 alveolar cells: flattened cells 97% of alveolar surface Small amount of cytoplasm Function: Provede minumum thickness for diffusion of gases Share in blood air barrier  Type 11 alveolar cells ❖Large cuboidal or rounded cells. ❖Form 3% of alveolar epithelium. ❖Apical surface contain microvilli ❖Vesicular nucleus. ❖Cell organoids. ❖Function: secrete surfactant which reduce the surface tention of alveoli preventing them from collapse at the end of expiration.