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Similar to The respiratory system
The respiratory system
- 1. THE RESPIRATORY SYSTEM The Exchange of Gases
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- 4. Breathing Breathing is theexchange of gases. The respiratory and cardiovascular systems combine to provide an efficient delivery system that carries oxygen to our body tissues and removes carbon dioxide from them. This transportation involves four separate processes:
- 5. - 1. Pulmonary ventilation(breathing), which is the movement of gases into and out of the lungs 2. Pulmonary diffusion, which is the exchange of gases between the lungs and the blood 3. Transport of oxygen and carbon dioxide via the blood 4. Capillary gas exchange, which is the exchange of gases between the capillary blood and the metabolically active tissue.
- 6. - The first twoprocesses are referred to as external respiration because they involve moving gases from outside the body into the lungs and then the blood. Once the gases are in the blood they must travel to the tissues. When blood arrives at the tissues, the fourth step of respiration occurs. This gas exchange between the blood and the tissues is called internal respiration. Thus external and internal respiration are linked by the circulatory system.
- 7. Pulmonary Ventilation Pulmonary ventilation,commonly referred to as breathing, is the process by which we move air into and out of our lungs. Air is typically drawn into the lungs through the nose, although the mouth must also be used when the demand for air exceedes the amount that can comfortably be brought in through the nose. Bringing air in through the nose has certain advantages over mouth breathing. The air is warmed and humidified as it swirls through the irregular surfaces (turbinates) inside the nose.
- 8. - Of equal importance,the turbinates churn the inhaled air, causing dust and other particles to contact and adhere to the nasal mucosa. This filters out all but the tiniest particles, minimizing irritation and the threat of respiratory infections. From the nose and mouth, the air travels through the pharynx, larynx, trachea, bronchi, and bronchioles, until it finally reaches the smallest respiratory units: alveoli. The alveoli are the sites of gas exchange in the lungs
- 9. - • The lungsare not directly attached to the ribs. Rather, they are suspended by the pleural sacs. These sacs envelop the lungs and contain a thin layer of pleural fluid that reduces friction during respiratory movements. In addition, these sacs are connected to the lungs and to the inner surface of the thoracic cage, causing the lungs to take the shape and size of the cage as the chest expands and contracts. • These relationships between the lungs, the pleural sacs, and the thoracic cage determine air flow into and out of the lungs. There are two phases: inspiration and expiration
- 10. Inspiration • Inspiration isan active process involving the diaphragm and the external intercostal muscles. The ribs and sternum are moved by the external intercostal muscles. The ribs swing up and out. The sternum swings up and forward. At the same time. the diaphragm contracts, flattening down toward the abdomen. When the lungs are expanded, the air within them has more space to fill, so the pressure within the lungs decreases. As a result, the pressure in the lungs (intrapulmonary pressure) is less than pressure of the air outside the body. Because the respiration tract is open to the outside, air rushes into the lungs to reduce this pressure difference. Thus air is brought into the lungs during inspiration.
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- 14. Expiration • At rest,expiration is usually a passive process involving the relaxation of the inspiratory muscles and elastic recoil of the lung tissue. As the external intercostal muscles relax, the ribs and sternum lower back into their resting position. This increases the pressure in the thorax, so air is forced out of the lungs. Thus expiration is accomplished. During forced breathing, expiration becomes a more active process.
- 15. Pulmonary Diffusion • Gasexchange in the lungs, called pulmonary diffusion, serves two major functions: 1. It replenishes the blood oxygen supply that has been depleted at the tissue level where it is used for oxidative energy production. 2. It removes carbon dioxide from returning venous blood.
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- 17. - • Pulmonary diffusionhas two requirements: air that brings oxygen into the lungs and blood to receive the oxygen and give up carbon dioxide and give up carbon dioxide. Air was brought into the lungs during pulmonary ventilation; now gas exchange must occur between this air and the blood.
- 18. The Respiratory Membrane Gasexchange between the air in the alveoli and the blood in the pulmonary capillaries occurs across the respiratory membrane (also called the alveolar-capillary membrane) which is composed of a) the alveolar wall b) the capillary wall, and c) their basement membranes.
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- 20. Partial Pressure ofGases • The air we breathe is a mixture of gases. Each exerts pressure in proportion to its concentration in the gas mixture. The individual pressures from each gas in a mixture are referred to as partial pressures. According to Dalton`s law, the total pressure equals the sum of the partial pressures of the individual gases in that mixture.
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- 23. - • The airwe breathe is composed of 79.04% nitrogen (N2), 20.93% oxygen (O2), and 0.03% carbon dioxide (CO2). If the total atmospheric pressure is 760 mmHg, then the partial pressure of nitrogen (PN2) in air is 600.7 mmHg (79.04% of the total 760 mmHg pressure). Oxygen`s partial pressure (PO2) is 159.0 mmHg (20.93% of 760 mmHg ), and carbon dioxide`s partial pressure (PCO2) is 0.03% of 760 mmHg ).
- 24. Gas Exchange inthe Alveoli • Differences in the partial pressures of the gases in the alveoli and the gases in the blood create a pressure gradient across the respiratory membrane. This forms the basis of gas exchange during pulmonary diffusion
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- 26. Oxygen Transport • Oxygenis transported by the blood either combined with hemoglobin (Hb) in the red blood cells (>98%) or dissolved in the blood plasma (<2%). Each molecule of hemoglobin can carry four molecules of oxygen. When oxygen binds to hemoglobin, it forms oxyhemoglobin; hemoglobin that is not bound to oxygen is referred to as deoxyhemoglobin. The binding of oxygen to hemoglobin depends on the Po2 in the blood and the bonding strength or affinity, between hemoglobin and oxygen.
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- 28. - There are otherfactors which affect this bonding affinity, such as the level of pH and blood temperature – higher pH and lower blood temperature increase the bonding affinity between hemoglobin and oxygen. The The pH in the lungs is generally high, so hemoglobin passing through the lungs has a strong affinity for oxygen, encouraging high saturation. At the tissue level, however, the pH is lower, causing oxygen to dissociate from hemoglobin, thereby supplying oxygen to the tissues. In the lungs, where the blood might be a bit cooler, hemoglobin`s affinity for oxygen is increased. This encourages oxygen binding.
- 29. Carbon Dioxide Transport •Carbon dioxide also relies on the blood for transportation. Once carbon dioxide is released from the cells, it is carried in the blood primarily in three forms: 1) Dissolved in plasma (7-10%) 2) As bicarbonate ions resulting from the dissociation of carbonic acid (60-70%) 3) Bound to hemoglobin (20-30%) – when carbon dioxide binds to hemoglobin, they form a compound called carbaminohemoglobin. Carbon dioxide binding depends on the oxygenation of the hemoglobin and the partial pressure of CO2
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- 31. The Regulation ofPulmonary Ventilation • The respiratory muscles are under the direct control of motor neurons, which are in turn regulated by respiratory centers located within the brainstem (in the medulla oblongata and pons). These centers establish the rate and depth of breathing by sending out periodic impulses to the respiratory muscles. However, the respiratory centers don`t act alone in controlling breathing. Its regulation is also determined by a changing chemical environment in the body
- 32. Voluntary Control • Wecan exert some voluntary control over our breathing through the cerebral motor cortex. However, this voluntary control can be overridden by the involuntary control of the respiratory centerIf we try to hold our breath, at some point, regardless of our conscious decision to suppress breathing, our carbon dioxide and H+ levels become quite high, our oxygen level drops, and our inspiratory center decides that breathing is imperative and it forces us to inhale,.
- 33. Respiratory System –Anatomy and Physiology The respiratory system is made up of the organs involved in the interchanges of gases and consists of the: • nose • mouth (oral cavity) • pharynx (throat) • larynx (voice box) • trachea (windpipe) • bronchi • lungs
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- 35. The Upper RespiratoryTract • The upper respiratory tract includes the following: • nose • nasal cavity • mouth • pharynx • larynx • trachea
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- 38. Nose and NasalCavity The nose is the uppermost part of the respiratory tract. It is made up to two bones and cartilage. It forms a hollow passage that connects the nostrils and the top of the throat. This passage is called the nasal cavity . It is lined with a mucous membrane which bears tiny hairs. The function of the nose is to filter, warm and moisten the air before it moves on to other parts of the respiratory tract. The tiny hairs trap the dust particles, bacteria and other foreign bodies that enter the nose. These hairs also induce sneezing to remove foreign bodies lodged in the nose.
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- 40. Mouth and Pharynx Thepharynx is a passageway from the back of the mouth (oropharynx) and nose (nasopharynx) to the upper part of the esophagus (laryngopharynx) and into the voice box, or larynx. The pharynx acts like a station where the food tube and the air tube meet. Food beings swallowed is prevented from entering the air tube by a thin structure, called epiglottis , that closes the air tube. This is why we cannot breathe while we are swallowing.
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- 42. Larynx and Trachea At the lower end of the pharynx is the larynx which forms part of the air tube. It is made of cartilage. One of its functions is production of voice. It does this with the help of either one of two pairs of vocal cords. When air from the lungs passes over the stretched vocal cords, vibrations are produced. The tongue palate and lips modify the vibrations to produce speech. Another function of the larynx is to prevent choking. The elongated space between the vocal cords is called glottis .
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- 46. - The epiglottis foldsback over the glottis when we swallow food, so the food cannot enter the trachea or air tube. The trachea, or windpipe , begins just below the larynx and ends behind the upper part of the breastbone where it divides to form two tubes. The trachea is made of elastic tissue and smooth muscle. It also has rings of elastic cartilage that keep the trachea open when the neck moves. It is lined with a mucous membrane and hair like projections called cilia . Mucus helps trap dust and bacteria in the incoming air. The cilia move the mucus upward to clear the respiratory tract.
- 47. The Lower RespiratoryTract The lower respiratory tract includes the following: • airways (bronchi and bronchioles) • air sacs (alveoli) • lungs
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- 50. Bronchi, Bronchioles andAlveoli The trachea branches into two tubes-the bronchi. Each bronchus (singular of bronchi) enters the lung and branches into narrower tubes called bronchioles . The walls of the bronchi and larger bronchioles are supported by cartilage. Their walls produce mucus which is moved upward by the cilia to clear the air passage. Each bronchiole ends in balloon like air sacs called alveoli .
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- 53. - The alveoli havethin walls which are surrounded by blood vessels. The bronchi and bronchioles form the air passage into the lungs. The exchange of oxygen and carbon dioxide takes place in the alveoli. There are about 300 million alveoli in the lungs. These alveoli increase the surface area of the lungs and allow many blood vessels to collect oxygen.
- 54. Lungs The lungs area pair of conical organs present in pleural cavities; both the lungs together form an important part of the human respiratory system. Left lung is divided into 2 lobes (superior and inferior) while the right one in 3 (superior, inferior and middle). Each lung has a median slit and hilus (or hilum).
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- 56. Bye Bye –See You Soon!