Alveolar epithelium contains two cell types. Type I cells completely cover the alveolar luminal surface and provide a thin surface for gas exchange. This simple squamous epithelium is so thin (-25 nm) that its details are beyond the resolution of the light microscope.

Type II cells are rounded, plump, cuboidal-like cells that sit on the basal lamina of the epithelium and contain membrane-bound granules of phospholipid and protein (lamellar bodies). The contents of these lamellar bodies are

secreted onto the alveolar surface to provide a coating of surfactant that reduces alveolar surface tension.

Alveolar macrophages (dust cells) are found on the surface of the alveoli.

Derived from monocytes that extravasate from alveolar capillaries, alveotar macrophages are part of the mononu – clear phagocyte system. Dust cells, as their name implies, continuously remove particles and other irritants in the alveoli by phagocytosis.

New words

respiratory bronchioles – дыхательные бронхиолы

hybrids – гибриды

respiratory portions – дыхательные части

airways – воздушные трассы

bronchiolar – бронхиолярный

terminal bron chioles – предельные бронхиолы

passageway – проходы

tocomprise – включить

ducts – трубочки

sinuous tubes – извилистые трубы

thin-walled – окруженный тонкой стеной

sacs – мешочки

respiratory tree – дыхательное дерево

hemoglobin – гемоглобин

apical – апикальный

38. Pleura

Visceral pleura is a thin serous membrane that covers the outer surface of the lungs. A delicate connective tissue layer of collagen and elastin, containing lymphatic channels, vessels, and nerves, supports the membrane. Its surface is covered by simple squamous mesothelium with microvilli.

Parietal pleura is that portion of the pleura that continues onto the inner aspect of the thoracic wall. It is continuous with the visceral pleura and is lined by the same me-sothelium.

Pleural cavity is a very narrow fluid-filled space that contains monocytes located between the two pleural membranes. It contains no gases and becomes a true cavity only in disease (e. g., in pleural infection, fluid and pus may accumulate in the pleural space). If the chest wall is punctured, air may enter the pleural space (pneumothorax), breaking the vacuum, and allowing the lung to recoil. Parietal pleura lines the inner surface of the thoracic cavity; visceral pleura follows the contours of the lung itself.

Pleural cavity: The pleural cavity is the space between the parietal and viscer al layers of the pleura. It is a sealed, blind space. The introduction of air into the pleural cavity may cause the lung to collapse (pneumothorax).

It normally contains a small amount of serous fluid elaborated by mesothelial cells of the pleural membrane.

Pleural reflections are areas where the pleura changes direction from one wall to the other. The sternal line of reflection is where the costal pleura is con tinuous with the mediastinal pleura behind the sternum (from costal cartilages 2–4). The pleural margin then passes inferiorly to the level of the sixth costal cartilage. The costal line of reflection is where the costal pleura becomes continuous with the diaphragmatic pleura from rib 8 in the mid-clavicular line, to rib 10 in the midaxillary line, and to rib 12 lateral to the vertebral column. Pleural recesses are potential spaces not occupied by lung tissue except during deep inspiration. Costodiaphragmatic recesses are spaces below the inferior borders of the lungs where costal and diaphragmatic pleura are in contact. Costomediastinal recess is a space where the left costal and mediastinal parietal pleura meet, leaving a space due to the cardiac notch of the left lung. This space is occupied by the lingula of the left lung during inspiration.

In nervation of the parietal pleura: The costal and peripheral portions of the diaphragmatic pleura are supplied by intercostal nerves.

The central portion of the diaphragmatic pleura and the medi astinal pleura are supplied by the phrenic nerve.

New words

visceral – висцеральный

pleura – плевра

dcollagen – коллаген

elastin – эластин

lymphatic channels – лимфатические сосуды

nerves – нервы

squamous – чешуйчатый

microvilli – микроворсинки

parietal pleura – париетальная плевра

visceral pleura – висцеральная плевра

costal – реберный

39. Nasal cavities

The anatomical structures that play a central role in the respiratory system are located in the head and neck as well as the thorax.

Nasal cavities are separated by the nasal septum, which consists of the vomer, the perpendicular plate of the ethmoid bone, and the septal cartilage. The lateral wall of each nasal cavity features three scroll-shaped bony structures called the nasal conchae. The nasal cavities communicate posteriorly with the nasopharynx through the choanae. The spaces inferior to each concha are called meatus. The paranasal sinuses and the nasolacrimal duct open to the meati. The inferior concha is a separate bone, and the superior and middle conchae are parts of the ethmoid bone

Inferior meatus. The only structure that opens to the inferior meatus is the nasolacrimal duct This duct drains lacrimal fluid (i. e., tears) from theTneaTaraspect of the orbit to the nasal cavity.

Middle meatus: the hiatus semilumaris contains openings of frontal and maxillary sinuses and americy ethmoidal air cells. The bulla ethmoidalis contains the opening for the middle ethmoidal air cells.

Superior meatus contains an opening for thff posterior ethmoidal air cells.

Sphenoethmoidal recess is located above the superior concha and contains an opening for the sphenoid sinus.

Innervation Somatic innervation General sensory information from the lateral wall and septum of the nasal cavity is conveyed to the CNS by branches of V, and V2.

Autonomic innervation. Preganglionic parasympathetic fibers destined to supply the glands of the nasal mucosa and the lacrimal gland travel in the nervus intermedius and the greater superficial petrosal branches of the facial nerve (CN VII). These fibers synapse in the pte-rygopalatine ganglion, which is located in the pterygopa-latine fossa. Postganglionic fibers traveling to the mucous glands of the nasal cavity, paranasal air sinuses, hard and soft palate, and the lacrimal gland follow branches of V2 and in some cases V1, to reach their destinations.

New words

anatomical – анатомический

respiratory system – дыхательная система

head – голова

neck – шея

nasal cavities – носовые впадины

the perpendicular plate – перпендикулярная пластина

ethmoid – решетчатый

septal – относящийся к перегородке

nasal conchae – носовой раковина

paranasal – параносовой

sinuses – пазухи

nasolacrimal – назолакримальный

duct – трубочка

drain – проток

tears – слезы

orbit – орбита

maxillary – верхнечелюстной

bulla – булла

40. Pharynx and related areas

The pharynx is a passageway shared by the digestive and respira tory systems. It has lateral, posterior, and medial walls through out, but is open interiorly in its upper regions, communicating with the nasal cavity and the oral cavity. The anterior wall of the laryngopharynx is formed by the larynx. The pharyngeal wall con sists of a mucosa, a fibrous layer, and a muscularis, which is com posed of an inner longitudinal layer and an outer circular layer.

Nasopharynx is the region of the pharynx located directly poste rior to the nasal cavity. It communicates with the nasal cavity through the choanae.

The torus tubarius is the cartilaginous rim of the auditory The pharyngeal recess is the space located directly above and behind the torus tubarius; it contains the nasopharyn-geal tonsil. The salpingopharyngeal fold is a ridge consisting of mucosa and the underlying salpingopharyngeus muscle.

Oropharynx is the region of the pharynx located directly posterior to the oral cavity. It communicates with the oral cavity through a space called the fauces. The fauces are bounded by two folds, consisting of mucosa and muscle, known as the anterior and posterior pillars.

The tonsillar bed is the space between the pillars that houses the palatine tonsil.

Laryngopharynx is the region of the pharynx that surrounds the larynx. It extends from the tip of the epiglottis to the cricoid car tilage. Its lateral extensions are known as the piriform recess.

Oral cavity: the portion of the oral cavity that is posterior to the lips and anterior to the teeth is called the vestibule. The oral cavi ty proper has a floor formed by the mylohyo-id and geniohyoid muscles, which support the tongue. It has lateral walls, consisting of the buccinator muscles and buccal mucosa, and a roof formed by the hard palate anteriorly and the soft palate posteriorly. Its posterior wall is absent and is replaced by an opening to the oropharynx, which is flanked by the pillars of the fauces.

The palate separates the nasal and oral cavities.

Hard palate is formed by the palatine process of the maxilla and the horizontal palate of the palatine bone. Its mucosa is supplied with sensory fibers from CN V2.

Soft palate consists of a fibrous membrane, the palatine aponeurosis, covered with mucosa. The portion that hangs down in the midline is the uvula.

The tongue is a mobile, muscular organ necessary for speech. It is divisible into an anterior two-thirds and a posterior one-third by the sulcus terminalis.

Muscles of the tongue. These include the intrinsic and extrinsic muscles (i. e., palatoglossus, stylogiossus, hyoglos – sus, genioglossus). All of the muscles are innervated by CN XII except the palatoglossus, which is supplied by CN X. Arterial supply: The tongue is supplied by the lingual branch of the external carotid aitery.

Venous drainage. The lingual veins, which lie on the un-der-surface of the tongue, drain to the internal jugular veins.

Lymphatic drainage. The tip of the tongue drains to the submental nodes, and the remainder of the anterior two-thirds drains first to submandibular, then to deep cervical nodes. The posterior one-third drains directly to deep cervi cal nodes.

New words

digestive – пищеварительный

pharyngeal – глоточный

mucosa – слизистая оболочка

fibrous layer – волокнистый слой

posterior nasal apertures – задние носовые апертуры

nasopharyngeal tonsil – миндалина

41. Oral cavity

The oral cavity forms in the embryo from an in-pocketing of the skin, stomodeum; it is, thus, lined by ectoderm. Functionally, the mouth forms the first portion of both the digestive and respiratory systems. In humans the margins of the lips mark the junction between the outer skin and the inner mucous lining of the oral cavity The roof of the mouth consists of the hard palate and, behind this, the soft palate which merges into the oropharynx. The lateral walls consist of the distensible cheeks. The floor of the mouth is formed principally by the tongue and the soft tissues that lie between the two sides of the lower jaw, or mandible. The tongue, a muscular organ in the mouth, provides the sense of taste and assists in chewing, swallowing, and speaking. It is firmly anchored by connective tissues to the front and side walls of the pharynx, or throat, and to the hyoid bone in the neck. The posterior limit of the oral cavity is marked by the fauces, an apperture which leads to the pharynx. On either side of the fauces are two muscular arches covered by mucosa, the glossopalatine and pharyngopalatine arches; between them lie masses of lymphoid tissue, the tonsils. Hiese are spongy lymphoid tissues composed mainly of lymphocytic cells held together by fibrous connective tissue. Suspended from the posterior portion of the soft palate is the soft retractable uvula. The palate develops from lateral folds of the primitive upper jaw. The hard palate, more anterior in position, underlies the nasal cavity The soft palate hangs like a curtain between the mouth and nasal pharynx. The hard palate has an intermediate layer of bone, supplied anteriorly by paired palatine processes of the maxillary bones, and posteriorly by the horizontal part of each palate bone. The oral surface of the hard palate is a mucous membrane covered with a stratified squamous epithelium. A submucosal layer contains mucous glands and binds the membrane firmly to the periosteum of the bony component. Above the bone is the mucous membrane that forms the floor of the nasal cavity.

The soft palate is a backward continuation from the hard palate. Its free margin connects on each side with two folds of mucous membrane, the palatine arches, enclosing a palatine tonsil. In the midline the margin extends into a fingerlike projection called uvula. The oral side of the soft palate continues as the covering of the hard palate, and the submucosa contains mucous glands. The intermediate layer is a sheet of voluntary muscle.

Besides separating the nasal passages from the mouth, the hard palate is a firm plate, against which the tongue manipulates food. In swallowing and vomiting the soft palate is raised to separate the oral from the nasal portion of the pharynx. This closure prevents food from passing upward into the nasopharynx and nose.

New words

mouth – рот

lips – губы

junction – соединение

distensible – растяжимый

cheeks – щеки

tongue – язык

taste – вкус

chewing – жевание

swallowing – глотание

42. Oral glands

All mammals are well supplied with oral glands. There are labial glands of the lips, buccal glands of the cheeks, lingual glands of the tongue, and palatine glands of the palate. Besides these, there are larger paired salivary glands. The parotid gland, near each ear, discharges into the vestibule. The submaxillary or submandibular gland lies along the posterior part of the lower jaw; its duct opens well forward under the tongue. The sublingual gland lies in the floor of the mouth. Saliva is a viscid fluid containing a mixture of all the oral secretions. It contains mucus, proteins, salts, and the enzymes ptyalin and maltase. Most of the ptyalin in human saliva is furnished by the parotid gland. The digestive action of saliva is limited to starchy food. Other uses of saliva include the moistening of food for easier manipulation by the tongue, the consequent facilitation of swallowing, and a lubrication by mucus that ensures a smoother passage of food down the esophagus to the stomach. Tonsils are spongy lymphoid tissues at the back of the throat, composed mainly of lymphocytic cells held together by fibrous connective tissue. There are three types of tonsils. The palatine tonsils, usually referred to as «the tonsils», are visible between the arches that extend from the uvula to the floor of the mouth. The pharyngeal tonsils, usually referred to as the adenoids, lie at the back of the throat. The lingual tonsils are on the upper surface of each side of the back of the tongue. The tonsils function to protect the pharynx and the remainder of the body from infectious organisms that become trapped in the mucous membrane lining the mouth, nose and throat. Chronic or acute inflammation of the tonsilses, called the tonsillitis.

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