Thoracic diaphragm. The term "diaphragm" in anatomy can refer to other flat structures such as the urogenital diaphragm or pelvic diaphragm, but "the diaphragm" generally refers to the thoracic diaphragm. Other mammals have diaphragms, and other vertebrates such as amphibians and reptiles have diaphragm-like structures, but important details of the anatomy vary, such as the position of lungs in the abdominal cavity. Structure[edit] The diaphragm is a dome-shaped structure of muscle and fibrous tissue that separates the thoracic cavity from the abdomen. The dome curves upwards. The superior surface of the dome forms the floor of the thoracic cavity, and the inferior surface the roof of the abdominal cavity.[3] As a dome, the diaphragm has peripheral attachments to structures that make up the abdominal and chest walls.
The muscle fibres of the diaphragm emerge from many surrounding structures. There are two lumbocostal arches, a medial and a lateral, on either side. Crura and central tendon[edit] Openings[edit] Base of lung. The base of the lung is broad, concave, and rests upon the convex surface of the diaphragm, which separates the right lung from the right lobe of the liver, and the left lung from the left lobe of the liver, the stomach, and the spleen.
Since the human diaphragm extends higher on the right than on the left side, the concavity on the base of the right lung is deeper than that on the left. Laterally and behind, the base is bounded by a thin, sharp margin which projects for some distance into the costodiaphragmatic recess of the pleura, between the lower ribs and the costal attachment of the diaphragm. The base of the lung descends during inspiration and ascends during expiration. See also[edit] zones of the lung External links[edit] base+of+lung at eMedicine Dictionary This article incorporates text from a public domain edition of Gray's Anatomy. Sphenoethmoidal recess. The sphenoethmoidal recess is a small space in the nasal cavity. It lies posterior and superior to the superior concha into which the sphenoidal sinus opens.
References[edit] This article incorporates text from a public domain edition of Gray's Anatomy. External links[edit] Costomediastinal recess. The costomediastinal recess is a potential space at the border of the mediastinal pleura and the costal pleura. It helps the lungs to expand during deep inspiration, although its role isn't as significant as the costodiaphragmatic recess, which has more volume. The lung expands into the costomediastinal recess even during quiet inspiration. The costomediastinal recess is most obvious in the cardiac notch of the left lung. See also[edit] External links[edit] Borders of the lung. The anterior border of the lung is thin and sharp, and overlaps the front of the pericardium. The anterior border of the right lung is almost vertical, and projects into the costodiaphragmatic recess; that of the left lung presents, below, an angular notch, the cardiac notch, in which the pericardium is exposed.
Opposite this notch the anterior margin of the left lung is situated some little distance lateral to the line of reflection of the corresponding part of the pleura. The posterior border of the lung is broad and rounded, and is received into the deep concavity on either side of the vertebral column. It is much longer than the anterior border, and projects, below, into the phrenicocostal sinus. The inferior border of the lung is thin and sharp where it separates the base from the costal surface and extends into the costodiaphragmatic recess; medially where it divides the base from the mediastinal surface it is blunt and rounded. [1] References[edit] External links[edit]
Lung. This article is about lungs in general. For human lungs, see Human lung. Sketch of the human lungs. The human lungs flank the heart and great vessels in the chest cavity[1] Air enters and leaves the lungs via a conduit of cartilaginous passageways—the bronchi and bronchioles. In this image, lung tissue has been dissected away to reveal the bronchioles[1] To understand the anatomy of the lungs, the passage of air through the nose and mouth to the alveoli must be studied.
Breathing is driven by muscular action; in early tetrapods, air was driven into the lungs by the pharyngeal muscles via buccal pumping, which is still found in amphibians. Medical terms related to the lung often begin with pulmo-, such as in the (adjectival form: pulmonary) or from the Latin pulmonarius ("of the lungs"), or with pneumo- (from Greek πνεύμων "lung").
Mammalian lungs Anatomy In humans, the trachea divides into the two main bronchi that enter the roots of the lungs. Non respiratory functions Avian lungs. Epiglottis. The epiglottis is a flap that is made of elastic cartilage tissue covered with a mucous membrane, attached to the entrance of the larynx. It projects obliquely upwards behind the tongue and the hyoid bone, pointing dorsally.
There are taste buds on the epiglottis.[2] Structure[edit] The epiglottis is shaped like a leaf, with the stem attached to the anterior part of the thyroid cartilage.[3] The epiglottis is one of nine cartilaginous structures that make up the larynx (voice box). Histology[edit] In a direct section of the epiglottis it can be seen that the body consists of elastic cartilage.
The entire lingual surface and the apical portion of the laryngeal surface (since it is vulnerable to abrasion due to its relation to the digestive tract) are covered by stratified squamous non-keratinized epithelium. Development[edit] The epiglottis arises from the fourth pharyngeal arch. Function[edit] Gag reflex[edit] Society and culture[edit] Clinical significance[edit] Inflammation[edit] History[edit] Respiratory tract. Structure[edit] Complete respiratory system The respiratory tract is divided into the upper airways and lower airways. The upper airways or upper respiratory tract includes the nose and nasal passages, paranasal sinuses, the pharynx, and the portion of the larynx above the vocal cords. The lower airways or lower respiratory tract includes the portion of the larynx below the vocal cords, trachea, bronchi and bronchioles. The lungs can be included in the lower respiratory tract or as separate entity and include the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.
The respiratory tract can also be divided into a conducting zone and a respiratory zone, based on the distinction of transporting gases versus exchanging them. From the bronchi the dividing tubes become progressively smaller with an estimated 20 to 23 divisions before ending at an alveolus. Upper respiratory tract[edit] Details of upper respiratory tract. Lower respiratory tract[edit] Respiratory tree[edit] Respiratory system. In fish and many invertebrates, respiration takes place through the gills.
Other animals, such as insects, have respiratory systems with very simple anatomical features, and in amphibians even the skin plays a vital role in gas exchange. Plants also have respiratory systems but the directionality of gas exchange can be opposite to that in animals. The respiratory system in plants also includes anatomical features such as holes on the undersides of leaves known as stomata.[2] Comparative anatomy and physiology Horses Horses are obligate nasal breathers which means that they are different from many other mammals because they do not have the option of breathing through their mouths and must take in oxygen through their noses.
Elephants The elephant is the only animal known to have no pleural space. Birds The respiratory system of birds differs significantly from that found in mammals, containing unique anatomical features such as air sacs. Reptiles Amphibians Fish Anatomy in invertebrates Insects. Type I pneumocyte. Type I pneumocyte cells (also called type I alveolar cells or squamous alveolar cells) are extremely attenuated cells that line the alveolar surfaces of the lungs. They cover 97% of the alveolar surface, with type II pneumocytes covering the remainder. These cells are so thin (sometimes only 25 nm) that the electron microscope was needed to prove that all alveoli are covered with an epithelial lining. It is important that these cells are thin so that gas exchange between the alveoli and blood can occur easily. Their main role is to provide a barrier of minimal thickness that is readily permeable to gases such as oxygen and carbon dioxide. Type I pneumocytes are unable to replicate and are susceptible to toxic insults.
In the event of damage, Type II cells can proliferate and/or differentiate into type I cells to compensate. Pleural cavity. In human anatomy, the pleural cavity is the potential space between the two pleurae (visceral and parietal) of the lungs. A pleura is a serous membrane which folds back onto itself to form a two-layered membrane structure. The thin space between the two pleural layers is known as the pleural cavity and normally contains a small amount of pleural fluid. The outer pleura (parietal pleura) is attached to the chest wall.
The inner pleura (visceral pleura) covers the lungs and adjoining structures, via blood vessels, bronchi and nerves. The parietal pleura is highly sensitive to pain, while the visceral pleura is not, due to its lack of sensory innervation.[1] Structure[edit] In humans, there is no anatomical connection between the left and right pleural cavities. The visceral pleura receives its blood supply from the bronchial circulation, which is the same as the lungs. Development[edit] Initially the intraembryonic coelom is one continuous space. Function[edit] Pleural fluid[edit] Respiratory system. Respiratory tract. Respiratory zone. The respiratory zone is the site of O2 and CO2 exchange with the blood. The respiratory bronchioles and the alveolar ducts are responsible for 10% of the gas exchange. The alveoli are responsible for the other 90%. The respiratory zone represents the 16th through the 23rd division of the respiratory tract.
See also[edit] Conducting zone External links[edit] Alveolar duct. Alveolar ducts are tiny ducts that connect the respiratory bronchioles to alveolar sacs, each of which contains a collection of alveoli (small mucus-lined pouches made of flattened endothelial cells). They are tiny end ducts of the branching airways that fill the lungs. Each lung holds approximately 1.5 to 2 million of them. The tubules divide into two or three alveolar sacs at the distal end. They are formed from the confluence openings of several alveoli. In human anatomy, respiratory bronchioles exist proximal to the alveolar ducts.
Additional images[edit] External links[edit] - "Respiratory System: lung (sheep), alveolar duct " Anatomy photo: respiratory/lung/lung7/lung3 - Comparative Organology at University of California, Davis - "Mammal, lung (EM, Medium)" Bronchiole. The bronchioles or bronchioli are the passageways by which air passes through the nose or mouth to the alveoli (air sacs) of the lungs, in which branches no longer contain cartilage or glands in their submucosa. They are branches of the bronchi, and are part of the conducting zone of the respiratory system. The bronchioles divide further into smaller terminal bronchioles which are still in the conducting zone and these then divide into the smaller respiratory bronchioles which mark the beginning of the respiratory region.
Structure[edit] A pulmonary lobule is the portion of the lung ventilated by one bronchiole. Bronchioles are approximately 1mm or less in diameter and their walls consist of ciliated cuboidal epithelium and a layer of smooth muscle. Bronchioles divide into even smaller bronchioles, called terminal, which are 0.5mm or less in diameter. Terminal bronchioles in turn divide into smaller respiratory bronchioles which divide into alveolar ducts. Bronchioles[edit] Apneustic center. The apneustic center (or apneustic area) of the lower pons appears to promote inspiration by stimulation of the I neurons in the medulla oblongata providing a constant stimulus. The apneustic center of pons sends signals to the dorsal respiratory center in the medulla to delay the 'switch off' signal of the inspiratory ramp provided by the pneumotaxic center of pons.
It controls the intensity of breathing. The apneustic center is inhibited by pulmonary stretch receptors. However, it gives positive impulses to the inspiratory (I) neurons. Pneumocyte. Borders of the lung. Internal intercostal muscles. Innermost intercostal muscle. Muscles of respiration. Pulmonary alveolus. Costal pleura. Left main bronchus. Right main bronchus. Tracheobronchial tree. Bronchopulmonary segment. Upper respiratory tract.
Lower respiratory tract. Pulmonary surfactant protein D. Intrapulmonary nodes. Conducting zone. Capillary. Lung. Bronchus. Alveolar duct. Lung receptor. Hilum of lung. Thoracic diaphragm. Terminal bronchiole. Human lung. Respiratory zone. Respiratory tract. Respiratory bronchiole.