Respiratory System By : dr. Sutrisno Darmosumarto, Sp.A Histology & Cell Biology Department Faculty of Medicine Gadjah Mada University

dr. INDRASTO H

The main function of respiratory system is to supply oxygen to cells

To fulfill that duty :pulmonary ventilation, diffusion of O2 and CO2 transport of O2 and CO2regulation of ventilation

Pulmonary ventilation :1.The inflow of air (inspiration) A. the downward of the diaphragm B. the elevation of the ribs 2. The outflow of air (expiration) : the elastic recoil of the lung alveoli.

In bronchial asthma : the abdominal recti musclethe diaphragmthe intercostal muscle

Conditioning of respiratory airA major function of conducting portion : cleansed moistened warmed

Cleaning the respiratory air :Large vibrissae Nasal fossae, Conchae (superior, medial, and inferior) by: 1. increasing the surface area 2. creating turbulence in the air flow Macrophages (dust cell)

Respirator epitheliumPseudostratified columnar ciliated epithelium Cilia on its apical surfaceGoblet cellsThe mucus

Moistening respiratory airThe mucusSerous secretions by :sero-mucous gland protects the alveoli from desiccation

Warming respiratory airConcha nasalisLarge venous plexuses (plexus Kiesselbachi) Every 20-30, the nasal fossae engorged with blood distention of the conchal mucosa decrease in the air flow reduce the air flow the incoming air is efficiently warmed

The respiratory air must flow freely is guaranteed by :nasal cavity is provided by osseus tissuethe wall of trachea, larynx, and bronchus are provided by cartilage tissue.

Diffusion of oxygen and carbon monoxide between respiratory air and blood capillary in the alveoliThe air in the alveoli is separated from capillary blood by:1.the cytoplasm of the epithelial cells2.the basal lamina of the epithelium3.the basal lamina of the endothelial cells4.the cytoplasm of the endothelial cellsThe thickness is 0.2 - 0.5 m

Capacity of exchange The oxygen and CO2 passes into the capillary blood is catalyzed by carbonic anhydrase The lungs contain 300 million alveoli increasing the internal exchange surface (70-80 m2)

Endothelial cellsExtremely thin The capillaries is continuous and not fenestratedCytologically, the nuclei and other organelles are clustered the remaining areas become extremely thin to increase the efficiency of gas exchangeNumerous pinocytotic vesicles

Squamous alveolar cells

So thin (25 nm)The nuclei and organelles are clusteredContains pinocytotic vesicles, desmosome bind adjacent cells occluding junction prevent the leakage of tissue fluidThe main role : a barrier of minimal thickness and permeable to gases

Great alveolar cellsInterspersed Have occluding and desmosome junctions Cuboidal Found in group (2 or 3) at the alveolar walls form anglesSit on the basal lamina

Great alveolar cells Mitochondria, GER, Golgi apparatus, and microvilli on their free apical surface vesicular or foamy cytoplasm multilamellar bodies (cytosomes) (0.2 m) granules with concentric/parallel lamellas limited by membranePhospholipids, mucopolysaccharides, and proteins, continuously synthesized and released an extracellular coating, surfactant surface activity

An aqueous proteinaceous hypophase covered by a monomolecular phospholipid film, primarily of dipalmitoyl lecithinFunctions in the economy of the lung Reducing the surface tension The surfactant

The surfactant

Reduction of surface tension less inspiratory force is needed to inflate the alveoli reducing the work of breathingIn premature birth infants exhibit labored breathing respiratory distress Hyaline membrane disease insufficient surfactant production difficulty in expanding the alveoliSurfactant synthesis can be induced problem

The surfactant Facilitates the transport of gases between the air and liquid phaseHas a bactericidal effect Not static constantly being turned over

The surfactant Gradually removed by the pinocytotic vesicles transport through the cell release into the interstitium continuous cycle of secretion and reabsorptionAlveolar lining fluids removed via the conducting passages by ciliary activity combined with bronchial mucus broncho-alveolar fluid aids in the removal of particulate and noxious components Within the fluids several lytic enzymes (e.g. lysozyme, collagenase, and beta-glucuronidase) derived from the alveolar macrophages

Microstructure of Respiratory OrganBlcok IV, Jan 25, 2006 Week 1 International ProgammeMicrostructure of Respiratory OrganBlcok IV, Jan 25, 2006 Week 1 International Progamme