L1 Histology Upper Respiratory System (Respiratory System) PDF

# Faculty of Medicine, Delta University for Science and Technology ## Level 2, Semester 4 - Module (Respiratory & renal) # The Respiratory System I - Contact: prof. Dr. Samar Asker - Department: Histology - Official email: [email protected] - Academic hours: - Day: 00:00-00:00 AM - Da...

# Faculty of Medicine, Delta University for Science and Technology ## Level 2, Semester 4 - Module (Respiratory & renal) # The Respiratory System I - Contact: prof. Dr. Samar Asker - Department: Histology - Official email: [email protected] - Academic hours: - Day: 00:00-00:00 AM - Day: 00:00-00:00 AM ## Learning Outcomes By the end of the lecture, the students will be able to: 1. Identify Division of the respiratory system. 2. Recognize the conducting part of the respiratory tract. 3. Correlate the structure of the conducting part respiratory tract to their functions. ## Conducting Portion: No gaseous exchange can occur in this part. It includes: 1. Nasal cavities 2. Nasopharynx 3. Oropharynx 4. Larynx 5. Trachea 6. Bronchi 7. Bronchioles ## Respiratory Portion: Gaseous exchange occurs. It includes: - Respiratory bronchioles - Lung alveoli Exchange of gases between the blood and the inspired air takes place. ## Nasal Cavities - It is divided into: - Anterior portion (Vestibule) - Posterior portion including: 1. Respiratory area 2. Olfactory area - Anterior portion (Vestibule) - It is lines with modified skin. - Epidermis: stratified squamous, keratinized epithelium - Dermis: with sweat and sebaceous glands - Function: filtration of the inspired air from the dust particles - Lined by mucous membrane formed of:  - Epithelium: pseudo- stratified columnar ciliated with goblet cells. - Corium: Dense fibro-elastic connective tissue infiltrated by: 1. Lymphocytes, macrophages and plasma cells 2. Serous and mucous glands 3. Large venous plexuses ## The Olfactory Area - Olfactory epithelium: A thick pseudo-stratified neuroepithelium; Consists of three types of cells:  - Sustentacular (Supporting) Cells: - Columnar cells with broad apexes and narrower bases - On their free surface are microvilli. - Contain a light-yellow pigment that is responsible for the color of the olfactory mucosa. - Olfactory Cells: - Bipolar neurons  - The dendrites extend towards the surface → olfactory hair vesicles which contain the basal bodies of the cilia. - About 6 to 12 cilia project into the surface from these basal bodies.  - The cilia are long, non-motile, they lie parallel to the surface of the mucosa and cover the microvilli of the supporting cells. - They respond to odoriferous substances. - The axon extend through the corium to the olfactory area in the brain. - Basal cells: - Small pyramidal cells with dark rounded nuclei. - Act as a stem cell for other cells - Corium: Dense fibro-elastic tissue, firmly adherent to the periosteum. - Highly vascular. - Contains tubulo-alveolar glands (the Bowman's glands) secrete a serous fluid - Freshens the olfactory cilia - Act as a solvent for the odorous gases ## The Larynx 1. The wall of the larynx is kept opened by several hyaline cartilages (the thyroid and cricoid) and elastic cartilages (the epiglottis, corniculate and cuneiform). 2. The larynx is lined by respiratory epithelium, except the superior surfaces of the epiglottis and vocal cords, which are covered by str. Sq. nonkeratinized epithelium. ## The Trachea - Starts at the end of the Larynx & end by dividing into 2 bronchi. - The wall of the trachea consists of 4 layers: - Mucosa: - Epithelium: Pseudo-stratified columnar ciliated with many goblet cells resting on clear but thin basement membrane. - C.T. Corium: Thin, rich in elastic fibers forming elastic membrane between the corium and the submucosa. - Submucosa: Loose areolar connective tissue contains mucoserous tracheal glands which Open into the surface epithelium by short ducts. - Fibro-Cartilaginous coat: 16-20 C-shaped rings of hyaline cartilage embedded in CT that fuse with the perichondrium of the cartilage plates. The 2 ends of the cartilage plates are connected by transverse smooth muscle fibres & flattened posteriorly opposite the oesophagus - Adventitia: Formed of CT ## The Cells of the Respiratory Epithelium 1. Ciliated cells: columnar ciliated cells. The cilia beat towards the larynx If destructed leads to chronic respiratory tract infections. 2. Goblet cells: have expanded apical parts distended with mucinogen granules. 3. Basal cells: Act as reserve stem cells for the ciliated cells and the goblet cells. 4. Serous cells: have apical electron dense granules. Produce a secretion of lower viscosity than that of the mucus. 5. Brush cells: slender columnar with many luminal microvilli, considered to be sensory receptors. 6. Neuro-endocrine cells: granule containing cells have neuroendocrine function. Secretes serotonin & calcitonin. 7. Migratory cells: Lymphocytes ## MCQ Time **Which one of the following is the lining of nasal vestibules?** a)Ps. Str . Columnar ciliated epithelium. b)Str. sq. epithelium. c)Str. col. epithelium. d)Transitional epithelium. e)Thin skin **Which one of the following describe the olfactory sensory cells?** a)Are unipolar neurons. b)The dendrites pass to the corium. c)Contains yellowish pigment which is responsible for the yellow color of the olfactory area. d)Have axonal processes confined to the epithelium surface. e)Are associated with odour specific receptors. **Which one of the following separates the lamina propria of the trachea from the submucosa?** a)A complete layer of smooth muscle fibers. b)A band of condensed fibro – elastic membrane. c)A band of elastic fibro cartilage. d)A C- shaped ring of hyaline cartilage. e)Irregular plates of hyaline cartilage. ## Practical - Epithelium of the nasal cavity: pseudo-stratified columnar ciliated with goblet cells, large venous plexuses, glands.  - Olfactory epithelium: Diagram of the olfactory epithelium after an electron micrograph.  - Olfactory hairs, pigment, micro-tubules, supporting cell, olfactory bipolar neuron, basal cell, Mucus,actory sensory/ceptor neuron , factory ithelium, Sustentacular cell, basal cell, lymphatic vessel, Bowman’s gland, blood vessel, lamina propria, cribriform plate.  - Respiratory Epithelium: cilia, goblet cell, lamina propria. - Trachea: mucosa (epithelium), submucosa (gland), cartilage, and Adventitia. # Thank You.