respiratory system by: hailey ortega, isabella manley, and aislonn rouse
TRANSCRIPT
Respiratory System
By: Hailey Ortega, Isabella Manley, and Aislonn Rouse
Function of Respiratory When breathing, the body takes in oxygen = inhaling
(inspiration). Then releases carbon dioxide = exhaling (expiration). Inhaling causes the rib cage to expand while muscles
contract. Exhaling causes the rib cage to return to normal while the
muscles relax. Attraction of water molecules creates surface tension
which makes it difficult to inflate the alveoli & can cause them to collapse.
Certain alveolar cells create surfactant, synthesized mixture of lipids & proteins that reduces alveoli’s tendency to collapse.
Respiratory Center Groups that compromise Respiratory Center in the
brainstem control both inspiration & expiration. Neurons are scattered throughout Pons & the
Medulla Oblongata. The Medullary rhythmicity area includes dorsal &
ventral respiratory groups which extend the length of the medulla oblongata.
The Dorsal Respiratory group controls the basic rhythm of inspiration.
The Ventral respiratory group generates impulses that increase inspiratory movements when more forceful breathing is required.
Major Structures
The major structures consist of: Nasal cavity Pharynx Larynx Trachea Lungs Bronchi Bronchioles Alveoli Diaphram
Nasal cavity The purpose of the sinuses is unclear, one theory is that sinuses help
humidify the air we breathe in; another is that they enhance our voices. The Nasal cavity is a hollow space behind the nose, divided into right and
left portions by the nasal septum. Bones that curl out from lateral walls of nasal cavity are nasal conchae. They
divide the cavity into passageways. They also support the mucous membrane and help increase its surface area. The Mucous membrane includes a network of blood vessels. As air passes over the membrane, heat leaves the blood & warms the air,
adjusting the temperature to that of the body’s. Incoming air is moistened as water evaporates from the mucous lining. The Membrane also secretes a mucus that traps dust & particles entering
with the air.
Paranasal SinusesIncludes: ► The Maxillary sinuses (the largest), in the
cheekbones.► The Frontal sinuses, in the low-center of the
forehead.► The Ethmoid sinuses, between the eyes, at the
nasal bridge.► The Sphenoid sinuses, in bones behind the nasal
cavity. These sinuses are resonant chambers that affect the
quality of voice and also reduce weight of skull. The sinuses are lined with soft, pink tissue called
mucosa. Normally, the sinuses are empty except for a thin layer of mucus.
The inside of the nose has ridges called turbinates. Normally, these structures help humidify and filter air.
Pharynx► located behind larynx, oral & nasal cavities.► Serves both the Respiratory & Digestive systems by passing air
between the Nasal cavity & Larynx, food & water from the oral cavity to the esophagus.
► Produces sounds of speech.► The Pharynx is divided into three regions according to location:
the Nasopharynx, the Oropharynx, and the Laryngopharynx (Hypopharynx).
► The Nasopharynx is the portion of the Pharynx that is posterior to the Nasal Cavity and extends inferiorly to the Uvula.
► The Oropharynx is posterior to the Oral Cavity.► The most inferior portion of the Pharynx, the Laryngopharynx,
extends from the Hyoid bone down to the lower margin of the Larynx.
► The upper part of the pharynx (throat) lets only air pass through while Lower parts permit air, foods, and fluids to pass.
Larynx
Is an Enlargement in the airway, below Pharynx, at top of Trachea.
Conducts air in & out of trachea and prevents foreign objects from entering.
Composed of cartilages such as Cricoid, epiglottic cartilages & the thyroid (Adam’s apple).
Epiglottic cartilage supports the Epiglottis, a flaplike structure which allows air to enter the Larynx.
The Larynx rises during swallowing & Epiglottis presses downward, partially covering opening into Larynx & prevents foods & liquids from entering the air passages.
The Larynx also contains vocal cords.
The Larynx plays an essential role in human speech. During sound production, vocal cords close together & vibrate as air expelled from lungs passes between them.
False vocal cords have no role in sound production, but help close off the larynx when food is swallowed.
Air forced between true vocal cords causes cords to vibrate side to side and generates sound waves.
Changes the shape of the Pharynx & oral cavity. The tongue & lips transform sound waves into words.
During breathing, the vocal cords are relaxed and the Glottis is a triangular slit. When food is swallowed muscles close the glottis, preventing food from entering the trachea.
Continued…
Trachea The trachea, commonly called the windpipe, is the
main airway to the lungs. Divides into right and left bronchi at level of the fifth thoracic vertebra, channeling air to right or left lung.
The hyaline cartilage in the tracheal wall provides support and keeps the trachea from collapsing.
The mucous membrane that lines the trachea is ciliated pseudostratified columnar epithelium, similar to that in the nasal cavity and nasopharynx.
Goblet Cells produce mucus that trap airborne particles and microorganisms. The cilia propel mucus upward, where it is either swallowed or expelled.
Bronchial Tree
Begins with the right & left Primary Bronchi. First, divides into secondary bronchi then into tertiary bronchi then into finer tubes such as Bronchioles & continue to divide into terminal & respiratory bronchioles and then finally into alveolar ducts.
Ducts lead to the thin-walled outerpouchings. Alveolar sacs lead to microscopic air sacs called alveoli.
Structure of bronchus is similar to the trachea, but tubes that branch have less cartilage and the bronchioles lack cartilage.
The Alveoli provide large surface area through which gases can be exchanged.
Oxygen diffuses through alveolar walls & enters the blood in nearby capillaries.
Carbon dioxide diffuses from blood though walls & enters alveoli.
Lungs
Soft, spongy, cone-shaped organs contained in thoracic cavity.
The Diaphragm & thoracic cavity enclose the lungs. Right & left lungs are separated medially by mediastinum.
Visceral pleura is a layer of serous membrane that attaches to each lung surface & folds back to become Parietal Pleura.
Parietal Pleura forms part of the mediastinum & also lines inner wall of the thoracic cavity.
Potential space between visceral and parietal pleura is called the Pleural Cavity which contains serous fluid that reduces friction during breathing.
The lungs also hold the pleural membranes together.
Gas Exchange Alveoli carry on the vital process of exchanging gases
between air & blood.
Layers of epithelial cells, tissue & collagenous fibers together compromise the Respiratory Membrane which blood & alveolar air exchange across.
Gas molecules from air may enter or dissolve in liquid such as when inspired gases dissolve in blood in the alveolar capillaries.
When a mix of gases dissolve in blood, the resulting concentration of gas is proportional to its partial pressure.
Gas diffuses between blood & surroundings from areas of higher partial pressure to lower until pressures in both regions reach equilibrium.
Oxygen Transport
► Almost all the oxygen that blood transports binds to the protein, hemoglobin in red blood cells. The remainder oxygen dissolves in plasma.
► In the lungs, oxygen dissolves in blood and combines with iron atoms of hemoglobin to form oxyhemoglobin.
► These molecules release oxygen as Po2 decreases, the oxygen is diffused into nearby cells that have been depleted of their oxygen supply during cellular respiration.
► More oxygen is released as the blood concentration of carbon dioxide increases, as the blood becomes more acidic, or as the temperature increases.
► A defiency of o2 reaching the tissues known as hypoxia, may occur because of decreased arterial Po2, diminished ability of the blood to transport o2, inadequate blood flow, or a defect at the cellular level.
Carbon Dioxide Transport► Blood transports carbon dioxide in one of three forms: as carbon
dioxide dissolved in plasma, part of compound formed by bonding to hemoglobin, or in the form of a bicarbonate ion.
►The amount of carbon dioxide that dissolves in plasma is determined by its partial pressure. The higher the Pco2 of the tissues, the more carbon dioxide will go into solution.
►Unlike oxygen, carbon dioxide bonds with amino groups of the globin (protein) portion of hemoglobin molecules.
►Carbon dioxide bonds with hemoglobin forming carbaminohemoglobin which releases carbon dioxide when decomposing in regions of low Pco2.
►Carbonic anhydrase speeds the reaction between carbon dioxide and water, the resulting carbonic acid then dissociates, releasing hydrogen ions and bicarbonate ions.
►Blood passes through capillaries of the lungs, its dissolved carbon dioxide diffuses into alveoli because of low Pco2 of alveolar air. Meanwhile, hydrogen and bicarbonate ions in red blood cells recombine to form carbonic acid which quickly breaks down to yield carbon dioxide and water.
Diseases/Disorders Asthma: The airways are persistently inflamed, and may
occasionally spasm, causing wheezing and shortness of breath. Allergies, infections, or pollution can trigger asthma’s symptoms
Chronic Obstructive Pulmonary Disease (COPD): lung conditions defined by an inability to exhale normally, which causes difficulty breathing
Chronic Bronchitis: A form COPD characterized by a chronic productive cough
Emphysema: Lung damage allows air to be tripped in the lungs in this form of COPD. Difficulty blowing air out is its hallmark
Acute Bronchitis: A sudden infection of the airways, usually by a virus
Cystic Fibrosis: A genetic condition causing poor clearance of mucus from the bronchi. The accumulated mucus results in repeated lung infections