Respiratory system

Nose, pharynx,larynx,trachea,bronchi, and the lungs.

Nose The nostril is the external nose opening. Nasal cavity is divided by nasal septum. The olfactory receptors are found in superior part of nasal cavity just below ethmoid bone Respiratory nasal mucosa rest on a rich network of thin walled veins, that warms the air as it flow past Epistaxis is common and profuse Sticky mucus produced by mucosal glands, moistened and trap bacteria air posteriorly The rest is ciliated respiratory mucosa, cilia moves contaminated mucus to pharynx

The lateral wall has three bony projections the chonchae. It increase the surface area of mucosa exposed to air, and cause air turbulence to trap foreign particles The nose is separated from the mouth by the palate, the anterior part is bony, posterior part is fleshy.

paranasal sinuses Surround nasal cavity Amplify sounds we speak Make bone of skull lighter Mucosal lining of sinuses is continuous with nasal passages and throat, so infection spread to them sinusitis Headache and upper jaw pain is usual result

Pharynx Is muscular passage 13 cm in length? It is divided in to Nasopharynx Oropharynx Laryngopharynx

Auditory tube opens into naso- pharynx. Tonsil is a cluster of lymphoid tissue. Otitis media result from spread of infection from naso-pharynx Pharyngeal tonsil is located high in nasopharynx called adenoids The palatine tonsils located in Oropharynx, lingual tonsil at base of the tongue.

Larynx Is the voice box, below pharynx? It is formed of nine cartilages, the largest are thyroid, cricoid, and the leaf like which cover the laryngeal opening, the epiglottis

The true vocal cords are ligaments covered by mucous membrane. They vibrate with expelled air Glottis is the slit like pathway between vocal cords The lower part of larynx and upper part of trachea.

Trachea Is cm in length? Begins at lower border of cricoid cartilage. Ends at level of T4-5, at Sternal angle. The trachea has C shaped cartilaginous rings, to keep it open, and allow food to pass to esophagus. Lined by ciliated epithelium moves upward Tracheostomy is life saving open in trachea

Tracheostomy and T tube

Primary bronchi Start at angle of Lewis, by division of trachea RT is wider, shorter and more in line with trachea. Foreign bodies usually enter right bronchus

Continue The primary bronchi enter lung,divide into secondary and tertiary bronchi Smallest of conducting passages is bronchioles This is called respiratory tree Respiratory bronchioles, alveolar duct and alveolar sacs and alveoli are site of gas exchange Rest are conducting zone structure

Lungs Occupy most of thoracic cavity except, the central part called the mediastinum (heart, big vessels). Lung has apex below the clavicle, base rest on diaphragm. Divided by fissures into lobes, RT has three lobes, LT has two lobes. The lung is covered by glistening membrane the pleura which has parietal and visceral layer Pleurisy inflammation of pleura

Alveoli the functional units of the lungs are the air sacs called alveoli. There are millions of alveoli in each lung, and their total surface area is estimated to be 700 to 800 square feet. Each alveolus is surrounded by a network of pulmonary capillaries. there are only two cells between the air in the alveoli and the blood in the pulm.capillaries.

The respiratory membrane The respiratory membrane consists of the alveolar and capillary walls. Gas exchange occurs across this membrane.  Characteristics of this membrane :..Type I cells are thin, squamous epithelial cells that constitute the primary cell type of the alveolar wall. Oxygen diffusion occurs across these cells...Type II cells are cuboidal epithelial cells that are interspersed among the type I cells. Type II cells secrete pulmonary surfactant (a phospholipid bound to a protein) that reduces the surface tension of the moisture that covers the alveolar walls...Alveolar macrophage (dust cells) wander among the other cells of the alveolar wall removing debris and microorganisms...A thin epithelial basement membrane forms the outer layer of the alveolar wall...A dense network of capillaries surrounds each alveolus. The capillary walls consist of endothelial cells surrounded by a thin basement membrane. The basement membranes of the alveolus and the capillary are often so close that they fuse.

Cont, Respiratory membrane consists of 1.Alveolar type 1 epithelium 2.Fused basement membrane of both alveolar and endothelial cells 3.Endothelial cells of capillaries

PSEUDOSTRATIEIED EPITHELIUM CILIATED This epithelium may be ciliate with goblet cells Example: Trachea Larger bronchi