HISTO RESPIRATORY

• The trachea is a tube that carries air to and from the lungs, lined with ciliated pseudostratified columnar epithelium, which helps move mucus and debris out of the lungs

  
• The respiratory system consists of organs working together to get oxygen into the body and remove carbon dioxide, with the lungs being the main organs, made up of alveoli where gas exchange occurs

  
• The diagram of the respiratory system shows parts like the nasal cavity, pharynx, larynx, trachea, bronchi, and lungs, divided into the conducting portion and the respiratory portion

  
• The respiratory system functions include supplying oxygen, filtering air, producing sound, containing smell receptors, maintaining acid-base balance, and removing excess water and heat
• Two functional divisions of the respiratory system are the conducting portion, which delivers air to the lungs, and the respiratory portion, responsible for gaseous exchange
• Two structural divisions of the respiratory system are the upper respiratory tract (nose to larynx) and the lower respiratory tract (trachea onwards)
• The nasal cavity is lined with respiratory epithelium, pseudostratified ciliated columnar epithelium with goblet cells, and contains structures like vibrissae, sebaceous and sweat glands
• The olfactory epithelium in the nasal cavity lacks goblet cells and contains olfactory cells, sustentacular cells, and basal cells in the lamina propria
• Anosmia, the loss of smell, can occur due to various reasons affecting the olfactory sensory neurons in the nose
• Paranasal sinuses are cavities in the skull bones lined with thinner respiratory epithelium, communicating with nasal cavities and producing mucus moved by ciliated epithelial cells
• Sinusitis is an inflammatory process of the sinuses often due to obstruction of drainage orifices
• The nasopharynx is continuous with the nasal cavity, lined by respiratory epithelium, while the oropharynx and laryngopharynx are lined by stratified squamous non-keratinized epithelium
• The larynx has two types of epithelium: respiratory epithelium (pseudostratified ciliated columnar epithelium with goblet cells) and stratified squamous epithelium
• The respiratory system consists of organs like the lungs, alveoli, and capillaries, working together to get oxygen into the body and remove carbon dioxide

  
• The lungs are made up of millions of tiny air sacs called alveoli, lined with capillaries where oxygen from the air passes into the blood, while carbon dioxide is removed

  
• Diagram of the respiratory system shows parts like the nasal cavity, pharynx, larynx, trachea, bronchi, and lungs, including the conducting and respiratory portions

  
• The walls of the nasopharynx are supported by bone and skeletal muscle tissue
• The pharyngeal tonsil, an unencapsulated patch of lymphoid tissue, is located in the posterior aspect of the nasopharynx
• In the larynx, there are two types of epithelium: respiratory epithelium and stratified squamous nonkeratinized epithelium
• The larynx has cartilages like hyaline cartilages (e.g., thyroid cartilage) and elastic cartilages (e.g., epiglottis)
• The trachea is a 10 to 12 cm long tube connecting the larynx and primary bronchi, with a wall reinforced by 10-12 hyaline cartilage rings
• The trachea has three layers: mucosa, submucosa, and adventitia, with the mucosa composed of respiratory epithelium, lamina propria, and elastic lamina
• The bronchial tree starts at the tracheal bifurcation, with primary bronchi leading to intrapulmonary bronchi, bronchioles, and terminal bronchioles
• Terminal bronchioles are the smallest conducting airways without alveoli, lined with simple cuboidal nonciliated epithelium
• Clara cells in terminal bronchioles secrete surfactant, detoxify, have antimicrobial peptides, and act as stem cells
• Asthma is characterized by chronic inflammation in the bronchial tree, leading to bronchospasms
• The respiratory portion of the lungs conducts air and allows for gaseous exchange, starting with the alveoli
• The trachea is lined with ciliated pseudostratified columnar epithelium, which helps move mucus and debris out of the lungs

  
• The respiratory system consists of organs that work together to get oxygen into the body and remove carbon dioxide

  
• The lungs, the main organs of the respiratory system, are made up of millions of tiny air sacs called alveoli

  
• Oxygen from the air passes through the alveoli and into capillaries, which then carry the oxygen to the heart for distribution

  
• Carbon dioxide, a waste product, is carried by the blood to the lungs, where it is exhaled

  
• The diagram of the respiratory system shows parts like the nasal cavity, pharynx, larynx, trachea, bronchi, and lungs, including the conducting and respiratory portions

  
• Respiratory bronchioles resemble terminal bronchioles but occasionally have alveoli that permit gas exchange
• Alveolar ducts branch from respiratory bronchioles and are lined by openings of alveoli, leading to alveolar sacs
• Alveoli are small sacs responsible for the spongy structure of the lungs, separated by thin interalveolar septa
• Type I pneumocytes line around 95% of the alveolar surface, while Type II pneumocytes are more numerous and secrete pulmonary surfactant
• Alveolar macrophages help maintain a sterile environment in the lungs by ingesting inhaled particulates like dust and bacteria
• The blood-air barrier consists of thin layers facilitating the exchange of oxygen and carbon dioxide between alveoli and capillaries
• Infant Respiratory Distress Syndrome is caused by insufficient pulmonary surfactant production in premature infants