CARDIOVASCULAR AND RESPIRATORYSYSTEM SUMURY.pptx

Be ready to learn how it works
This is about cardiovascular system , consisting of heart and blood vessels
And also respiratory system of how we breath and the mechanisms behind.

1. ANATOMY AND PHYSIOLOGY OF CARDIOVASCULAR SYSTEM ( Unit Summary) By Adrien UWIZEYIMANA RN,MSN

2. WHAT IS CARDIOVASCULAR SYSTEM? The heart and blood vessels make up the circulatory system. The main function of the circulatory system is to provide oxygen, nutrients and hormones to muscles, tissues and organs throughout the body. Another part of the circulatory system is to remove waste from cells and organs so your body can dispose of it.

3. CONT’D The heart  pumps blood to the body through a network of arteries and veins (blood vessels). The circulatory system can also be defined as your cardiovascular system. Cardio means heart , and vascular refers to blood vessels .

4. Cardiac layers view

5. The four chambers of the heart 1.left atrium: left upper chamber 2.Right atrium: Right upper chamber 3.left ventricle: Left lower chamber 4.Right ventrical : Right lower chamber The septal wall separates the right lower chamber Valves Atrioventricular (AV) Valves : Control blood flow between the upper and lower chambers Tricuspid valve: On the right side between the atria and the ventricles Mitral valve: On the left side between the atria and the ventricles Pulmonic valve: Controls the flow between the right ventricle and pulmonary artery Aortic valve: Controls the flow between the left ventricle and the aorta

6. T he circulatory system circuits The circulatory system has three circuits. Blood circulates through ythe heart and through these circuits in a continuous pattern: The pulmonary   circuit:  This circuit carries blood without oxygen from the heart to the lungs. The pulmonary veins return oxygenated blood to the heart. The systemic circuit:  In this circuit, blood with oxygen, nutrients and hormones travels from the heart to the rest of the body. In the veins, the blood picks up waste products as the body uses up the oxygen, nutrients and hormones. The coronary circuit:  Coronary refers to the heart’s arteries . This circuit provides the heart muscle with oxygenated blood. The coronary circuit then returns oxygen-poor blood to the heart’s right upper chamber (atrium) to send to the lungs for oxygen.

7. Pulmonary and systemic circuit

8. Coronary circuit

9. Where coronary circulation begins The coronary arteries  originate as the right and left main coronary arteries which exit the ascending aorta just above the aortic valve (coronary ostia) . These two branches subdivide and course over the surface of the heart (epicardium) as they traverse away from the aorta.

10. Blood flow unoxygenated blood empties into the right atrium from the systemic circulation via the inferior vena cava and superior vena cava. The right atrium contracts and the tricuspid valve opens, allowing the blood to flow into the right ventricle The right ventricle contracts and the pulmonic valve opens, allowing the unoxygenated blood to enter the pulmonary artery to go to the lungs to pick up oxygen

11. Blood flow CONT' 4.Oxgenated blood returns from the lungs to the heart via the pulmonary vein and enters the left atrium. 5.The left atrium contracts and the mitral valve opens, allowing the blood to follow into the left ventricle The left ventricle contracts and the aortic valve opens, allowing the blood to flow into the aorta and systemic circulation. 6. Blood returns to the heart from the lower body via the inferior vena cava and from the upper body via the supper vena cava.

12. 4. Oxgenated blood returns from the lungs to the heart via the pulmonary vein and enters the left atrium. 5.The left atrium contracts and the mitral valve opens, allowing the blood to follow into the left ventricle The left ventricle contracts and the aortic valve opens, allowing the blood to flow into the aorta and systemic circulation. 6. Blood returns to the heart from the lower body via the inferior vena cava and from the upper body via the supper vena cava.

13. Blood flow summary

14. Heart Sounds Heart sounds are primarily generated from vibrations of cardiac structures caused by changes that create turbulent flow Under normal conditions, blood flow is laminar. With structural or hemodynamic changes turbulent flow results, which causes vibrational waves. These waves are transmitted through the chest wall and are the sounds practitioners auscultate with their stethoscopes. The sound transmits in the same direction as the blood flow.

15. Physiologic Heart Sounds Normal heart sounds are S1 and S2 The first heart sound (S1)  represents closure of the atrioventricular (mitral and tricuspid) valves as the ventricular pressures exceed atrial pressures at the beginning of systole . S1 is normally a single sound because mitral and tricuspid valve closure occurs almost simultaneously. Clinically, S1 corresponds to the pulse. The second heart sound (S2)  represents closure of the semilunar (aortic and pulmonary) valves S2 is normally split because the aortic valve closes before the pulmonary valve . 

16. Electrical conduction summary

17. The heart's electrical system Going back to the analogy of the central heating system, the pumps, pipes and radiators are of no use unless connected to a power supply. The pump needs electricity to work. The human heart has a similar need for a power source and also uses electricity. Thankfully we don’t need to plug ourselves in to the mains, the heart is able to create it’s own electrical impulses and control the route the impulses take via a specialized conduction pathway. This pathways is made up of 5 elements: 1.The sino -atrial (SA) node 2. The atrio-ventricular (AV) node 3. The bundle of his 4.The left and right bundle branches 5. The Purkinje fibers

18. Cont’d The SA node is the natural pacemaker of the heart. The SA node releases electrical stimuli at regular rate, the rate is dictated by the needs of the body. The electrical stimulus from the SA node eventually reaches the AV node and is delayed briefly so that the contracting atria have enough time to pump all the blood into the ventricles. One the atria are empty of blood the valves between the atria and ventricles close. At this point the atria begin to refill and the electrical stimulus passes through the AV node and bundle of his into the bundle branches and purkinje fibers.

19. Cont’d At this point the ventricles contract,(see blood flow). After contraction the ventricles are empty the atria are full and the valves between them are closed. The SA node is about to release another electrical stimulus and the process is about to repeat itself.

20. PRELOAD and AFTERLOAD Preload, also known as the left ventricular end-diastolic pressure (LVEDP), is the amount of ventricular stretch at the end of diastole. Think of it as the heart loading up for the next big squeeze of the ventricles during systole. Some people remember this by using an analogy of a balloon – blow air into the balloon and it stretches; the more air you blow in, the greater the stretch. Afterload, also known as the systemic vascular resistance (SVR), is the amount of resistance the heart must overcome to open the aortic valve and push the blood volume out into the systemic circulation. If you think about the balloon analogy, afterload is represented by the knot at the end of the balloon. To get the air out, the balloon must work against that knot. 

21. Control of Blood Pressure Changes in blood pressure are routinely made in order to direct appropriate amounts of oxygen and nutrients to specific parts of the body. For example, when exercise demands additional supplies of oxygen to skeletal muscles, blood delivery to these muscles increases, while blood delivery to the digestive organs decreases. Adjustments in blood pressure are also required when forces are applied to your body, such as when starting or stopping in an elevator.

22. Blood pressure can be adjusted by producing changes in the following variables: Cardiac output can be altered by changing stroke volume or heart rate. Resistance to blood flow in the blood vessels is most often altered by changing the diameter of the vessels (vasodilation or vasoconstriction). Changes in blood viscosity (its ability to flow) or in the length of the blood vessels (which increases with weight gain) can also alter resistance to blood flow.

23. The following mechanisms help regulate blood pressure: The cardiovascular center provides a rapid, neural mechanism for the regulation of blood pressure by managing cardiac output or by adjusting blood vessel diameter. Located in the medulla oblongata of the brain stem, it consists of three distinct regions:

24. Cont’d The cardiac center stimulates cardiac output by increasing heart rate and contractility. These nerve impulses are transmitted over sympathetic cardiac nerves. The cardiac center inhibits cardiac output by decreasing heart rate. These nerve impulses are transmitted over parasympathetic vagus nerves. The vasomotor center regulates blood vessel diameter. Nerve impulses transmitted over sympathetic motor neurons called vasomotor nerves innervate smooth muscles in arterioles throughout the body to maintain vasomotor tone, a steady state of vasoconstriction appropriate to the region.

25. The cardiovascular center receives information about the state of the body through the following sources: Baroreceptors  are sensory neurons that monitor arterial blood pressure. Major baroreceptors are located in the carotid sinus (an enlarged area of the carotid artery just above its separation from the aorta), the aortic arch, and the right atrium. Chemoreceptors  are sensory neurons that monitor levels of CO  2  and O  2 . These neurons alert the cardiovascular center when levels of O  2  drop or levels of CO  2  rise (which result in a drop in pH). Chemoreceptors are found in carotid bodies and aortic bodies located near the carotid sinus and aortic arch. Higher brain regions, such as the cerebral cortex, hypothalamus, and limbic system, signal the cardiovascular center when conditions (stress, fight‐or‐flight response, hot or cold temperature) require adjustments to the blood pressure.

26. The kidneys provide a hormonal mechanism for the regulation of blood pressure by managing blood volume The renin‐angiotensin‐aldosterone system of the kidneys regulates blood volume. In response to rising blood pressure, the juxtaglomerular cells in the kidneys secrete renin into the blood. Renin converts the plasma protein angiotensinogen to angiotensin I, which in turn is converted to angiotensin II by enzymes from the lungs. 

27. Angiotensin II activates two mechanisms that raise blood pressure: Angiotensin II constricts blood vessels throughout the body (raising blood pressure by increasing resistance to blood flow). Constricted blood vessels reduce the amount of blood delivered to the kidneys, which decreases the kidneys' potential to excrete water (raising blood pressure by increasing blood volume).

28. Cont’d Angiotensin II stimulates the adrenal cortex to secrete aldosterone, a hormone that reduces urine output by increasing retention of H  2 O and Na  +  by the kidneys (raising blood pressure by increasing blood volume).

29. Various substances influence blood pressure. Some important examples follow Epinephrine and norepinephrine, hormones secreted by the adrenal medulla, raise blood pressure by increasing heart rate and the contractility of the heart muscles and by causing vasoconstriction of arteries and veins. These hormones are secreted as part of the fight‐or‐flight response. Antidiuretic hormone (ADH), a hormone produced by the hypothalamus and released by the posterior pituitary, raises blood pressure by stimulating the kidneys to retain H  2 O (raising blood pressure by increasing blood volume).

30. Cont’d Atrial natriuretic peptide (ANP), a hormone secreted by the atria of the heart, lowers blood pressure by causing vasodilation and by stimulating the kidneys to excrete more water and Na  + (lowering blood pressure by reducing blood volume).

31. Cont’d Nitric oxide (NO), secreted by endothelial cells, causes vasodilation. Nicotine in tobacco raises blood pressure by stimulating sympathetic neurons to increase vasoconstriction and by stimulating the adrenal medulla to increase secretion of epinephrine and norepinephrine. Alcohol lowers blood pressure by inhibiting the vasomotor center (causing vasodilation) and by inhibiting the release of ADH (increasing H  2 O output, which decreases blood volume).

32. THANK YOU!

33. Anatomy of the Lymphatic and Immune Systems T he  immune system  is the complex collection of cells and organs that destroys or neutralizes pathogens that would otherwise cause disease or death. The lymphatic system, for most people, is associated with the immune system to such a degree that the two systems are virtually indistinguishable. The  lymphatic system  is the system of vessels, cells, and organs that carries excess fluids to the bloodstream and filters pathogens from the blood. The swelling of lymph nodes during an infection and the transport of lymphocytes via the lymphatic vessels are but two examples of the many connections between these critical organ systems.

34. Functions of the Lymphatic System A major function of the lymphatic system is to drain body fluids and return them to the bloodstream. Blood pressure causes leakage of fluid from the capillaries, resulting in the accumulation of fluid in the interstitial space—that is, spaces between individual cells in the tissues. In humans, 20 liters of plasma is released into the interstitial space of the tissues each day due to capillary filtration. Once this filtrate is out of the bloodstream and in the tissue spaces, it is referred to as interstitial fluid. Of this, 17 liters is reabsorbed directly by the blood vessels. But what happens to the remaining three liters? This is where the lymphatic system comes into play.

35. CONT’D It drains the excess fluid and empties it back into the bloodstream via a series of vessels, trunks, and ducts.  Lymph  is the term used to describe interstitial fluid once it has entered the lymphatic system. When the lymphatic system is damaged in some way, such as by being blocked by cancer cells or destroyed by injury, protein-rich interstitial fluid accumulates (sometimes “backs up” from the lymph vessels) in the tissue spaces. This inappropriate accumulation of fluid referred to as lymphedema may lead to serious medical consequences. As the vertebrate immune system evolved, the network of lymphatic vessels became convenient avenues for transporting the cells of the immune system. Additionally, the transport of dietary lipids and fat-soluble vitamins absorbed in the gut uses this system.

36. CONT’D Cells of the immune system not only use lymphatic vessels to make their way from interstitial spaces back into the circulation, but they also use lymph nodes as major staging areas for the development of critical immune responses. A  lymph node  is one of the small, bean-shaped organs located throughout the lymphatic system.

37. Structure of the Lymphatic System The lymphatic vessels begin as open-ended capillaries, which feed into larger and larger lymphatic vessels, and eventually empty into the bloodstream by a series of ducts. Along the way, the lymph travels through the lymph nodes, which are commonly found near the groin, armpits, neck, chest, and abdomen. Humans have about 500–600 lymph nodes throughout the body. Lymph flows from the lymphatic capillaries, through lymphatic vessels, and then is dumped into the circulatory system via the lymphatic ducts located at the junction of the jugular and subclavian veins in the neck. The lymphatic capillaries empty into larger lymphatic vessels, which are similar to veins in terms of their three-tunic structure and the presence of valves. These one-way valves are located fairly close to one another, and each one causes a bulge in the lymphatic vessel, giving the vessels a beaded appearance.

38. CONT’D The superficial and deep lymphatics eventually merge to form larger lymphatic vessels known as  lymphatic trunks On the right side of the body, the right sides of the head, thorax, and right upper limb drain lymph fluid into the right subclavian vein via the right lymphatic duct. On the left side of the body, the remaining portions of the body drain into the larger thoracic duct, which drains into the left subclavian vein. The thoracic duct itself begins just beneath the diaphragm in the  cisterna chyli , a sac-like chamber that receives lymph from the lower abdomen, pelvis, and lower limbs by way of the left and right lumbar trunks and the intestinal trunk.

39. The Organization of Immune Function The immune system is a collection of barriers, cells, and soluble proteins that interact and communicate with each other in extraordinarily complex ways. The modern model of immune function is organized into three phases based on the timing of their effects. The three temporal phases consist of the following: Barrier defenses  such as the skin and mucous membranes, which act instantaneously to prevent pathogenic invasion into the body tissues The rapid but nonspecific  innate immune response , which consists of a variety of specialized cells and soluble factors The slower but more specific and effective adaptive immune response , which involves many cell types and soluble factors, but is primarily controlled by white blood cells (leukocytes) known as lymphocytes, which help control immune responses

40. CONTD’ The cells of the blood, including all those involved in the immune response, arise in the bone marrow via various differentiation pathways from hematopoietic stem cells. These cells can be divided into three classes based on function: Phagocytic cells, which ingest pathogens to destroy them Lymphocytes, which specifically coordinate the activities of adaptive immunity Cells containing cytoplasmic granules, which help mediate immune responses against parasites and intracellular pathogens such as viruses

41. Lymphocytes lymphocytes are the primary cells of adaptive immune responses. The two basic types of lymphocytes, B cells and T cells, are identical morphologically with a large central nucleus surrounded by a thin layer of cytoplasm. They are distinguished from each other by their surface protein markers as well as by the molecules they secrete. While B cells mature in red bone marrow and T cells mature in the thymus, they both initially develop from bone marrow. T cells migrate from bone marrow to the thymus gland where they further mature. B cells and T cells are found in many parts of the body, circulating in the bloodstream and lymph, and residing in secondary lymphoid organs, including the spleen and lymph nodes. The human body contains approximately 10 12  lymphocytes.

42. B Cells B cells  are immune cells that function primarily by producing antibodies. An  antibody  is any of the group of proteins that binds specifically to pathogen-associated molecules known as antigens. An  antigen  is a chemical structure on the surface of a pathogen that binds to T or B lymphocyte antigen receptors. Once activated by binding to antigen, B cells differentiate into cells that secrete a soluble form of their surface antibodies. These activated B cells are known as plasma cells.

43. T Cells The  T cell , on the other hand, does not secrete antibody but performs a variety of functions in the adaptive immune response. Different T cell types have the ability to either secrete soluble factors that communicate with other cells of the adaptive immune response or destroy cells infected with intracellular pathogens.

44. Plasma Cells Another type of lymphocyte of importance is the plasma cell.   plasma cell  is a B cell that has differentiated in response to antigen binding, and has thereby gained the ability to secrete soluble antibodies. These cells differ in morphology from standard B and T cells in that they contain a large amount of cytoplasm packed with the protein-synthesizing machinery known as rough endoplasmic reticulum.

45. Natural Killer Cells A fourth important lymphocyte is the natural killer cell, a participant in the innate immune response. A  natural killer cell (NK)  is a circulating blood cell that contains cytotoxic (cell-killing) granules in its extensive cytoplasm. It shares this mechanism with the cytotoxic T cells of the adaptive immune response. NK cells are among the body’s first lines of defense against viruses and certain types of cancer.

46. Lymphocytes summary

47. Primary Lymphoid Organs and Lymphocyte Development The  primary lymphoid organs  are the bone marrow, spleen, and thymus gland. The lymphoid organs are where lymphocytes mature, proliferate, and are selected, which enables them to attack pathogens without harming the cells of the body.

48. Lymph Nodes Lymph nodes function to remove debris and pathogens from the lymph, and are thus sometimes referred to as the “filters of the lymph”. Any bacteria that infect the interstitial fluid are taken up by the lymphatic capillaries and transported to a regional lymph node. Dendritic cells and macrophages within this organ internalize and kill many of the pathogens that pass through, thereby removing them from the body.

49. RESPIRATORY SYSTEM I.Parts of respiratory system Nasal cavities: Nose and linked air passages Mouth Larynx Trachea Bronchi Bronchioles: small, thin tube Alveoli :air sac connected to the bronchioles Capillaries: a network of tiny blood vessels that cover the alveoli. Capillaries connect to a network of arteries and veins. Pulmonary artery: delivers blood containing carbon dioxide to the capillaries of the alveoli. Diaphragm: The main muscle for breathing located below the lungs;it separates the chest cavity from the abdominal cavity. Intercostal muscles: located between the ribs, intercostal muscles assist in breathing

50. RESPIRATORY SYSTEM Abdominal muscles: used to exhale when breathing fast Accessory muscles (neck and collarbone): used for breathing when the patient is having difficulty breathing. II.RESPIRATORY SYSTEM FUNCTION Nose and mouth wet and warm the air: cold and dry air irritate the lungs. Cilia in the nose and airway trap germs and other foreign particles in the air. Particles are swallowed, coughed, or sneezed out of the body The lungs exchange oxygen and carbon dioxide from blood vessels.

51. II.RESPIRATORY SYSTEM FUNCTION The pulmonary artery delivers blood containing carbon dioxide to the capillaries of the alveoli. Gas exchange takes, replacing carbon dioxide from hemoglobin in red blood cells with oxygen Respiration: Airway : carries oxygenated air to the lungs and removes carbon dioxide Muscle around the lungs expand and contract to force the lungs to exhale and inhale. These muscles are: inhalation muscles Diaphragm contracts, moving down increased space in the chest cavity, and enabling lungs to expand. Intercostal muscles pull the rib cage out and up, enlarging the chest cavity Air sucked through the nose and mouth as the lungs expand and travels down the trachea and bronchi, bronchioles and alveoli, where gas exchange occurs.

52. II.RESPIRATORY SYSTEM FUNCTION exhalation muscles The diaphragm and intercostals muscles contract, reducing space in the chest cavity and forcing air out of the lungs. RESIRATORY CONTROL The medulla oblongata portion of the brain controls breathing. Sensors in the carotid artery and aorta detect carbon dioxide and oxygen levels in the blood. These sensors signal when respiration should increase or decrease. sensors in the airways detect irritants and trigger the brain to cause coughing or sneezing by tightening smooth muscles around the airway, increasing the air pressure on exhalation. Sensors in the alveoli detect fluid buildup and signal the brain to trigger rapid, shallow breathing.

53. Breath Sounds Breath sounds come from the lungs when you breathe in and out. These sounds can be heard using a stethoscope or simply when breathing. Breath sounds can be normal or abnormal. Abnormal breath sounds can indicate a lung problem, such as: obstruction inflammation infection fluid in the lungs asthma

54. Types of breath sounds A normal breath sound is similar to the sound of air. However, abnormal breath sounds may include: rhonchi (a low-pitched breath sound) crackles (a high-pitched breath sound ) wheezing (a high-pitched whistling sound caused by narrowing of the bronchial tubes. Heard during exhalation ) stridor (a harsh, vibratory sound caused by narrowing of the upper airway, heard during inhalation)

55. What are the causes of abnormal breath sounds? Abnormal breath sounds are usually indicators of problems in the lungs or airways. The most common causes of abnormal breath sounds are: pneumonia heart failure chronic obstructive pulmonary disease (COPD), such as emphysema asthma bronchitis foreign body in the lungs or airways

56. Various factors cause the sounds described above: Rhonchi occur when air tries to pass through bronchial tubes that contain fluid or mucus. Crackles occur if the small air sacs in the lungs fill with fluid and there’s any air movement in the sacs, such as when you’re breathing. The air sacs fill with fluid when a person has pneumonia or heart failure.

57. CONT’ Wheezing occurs when the bronchial tubes become inflamed and narrowed. Stridor occurs when the upper airway narrows.

58. AUSCULTATION LAND MARKS

59. https://accesssurgery.mhmedical.com/content.aspx?bookid=1317&sectionid=72435493 Anatomy, Thorax, Lung Pleura And Mediastinum https://www.ncbi.nlm.nih.gov/books/NBK519048/

60. The Anatomy of the Pleura The pleura is a vital part of the respiratory tract whose role it is to cushion the lungs and reduce any friction which may develop between the lungs, rib cage, and chest cavity. The pleura consists of a two-layered membrane that covers each lung. The layers are separated by a small amount of viscous lubricant known as pleural fluid

61. Pleural fluid Pleural fluid is a serous fluid produced by the serous membrane covering normal pleurae Under normal conditions, pleural fluid is secreted by the parietal pleural  capillaries at a rate of 0.6 millilitre per kilogram weight per hour, and is cleared by lymphatic absorption leaving behind only 5–15 millilitres of fluid, which helps to maintain a functional  vacuum  between the parietal and visceral. Excess fluid within the pleural space can impair  inspiration  by upsetting the functional vacuum and hydrostatically   increasing the resistance against lung expansion, resulting in a fully or partially collapsed lung.

62. GAZ EXCHANGE The primary function of the  respiratory system is to take in oxygen and eliminate carbon dioxide. Inhaled oxygen enters the lungs and reaches the alveoli. The layers of cells lining the alveoli and the surrounding capillaries are each only one cell thick and are in very close contact with each other. This barrier between air and blood averages about 1 micron ( 1 / 10,000  of a centimeter, or 0.000039 inch) in thickness. Oxygen passes quickly through this air-blood barrier into the blood in the capillaries. Similarly, carbon dioxide passes from the blood into the alveoli and is then exhaled.

63. Blood–air barrier The  blood–air barrier or air–blood barrier, (alveolar–capillary barrier or membrane) exists in the gas exchanging region of the lungs. It exists to prevent air bubbles from forming in the blood , and from blood entering the alveoli . It is formed by the  types I pneumocytes  of the alveolar wall, the endothelial  cells of the capillaries  and the basement membrane between the two cells. The barrier is permeable  to molecular oxygen , carbon dioxide, carbon monoxide  and many other gases.

64. GAZ EXCHANGE

65. Mechanics of Ventilation Ventilation , or breathing, is the movement of air through the conducting passages between the atmosphere and the lungs. The air moves through the passages because of pressure gradients that are produced by contraction of the diaphragm and thoracic muscles.

66. Pulmonary ventilation Pulmonary ventilation is commonly referred to as breathing. It is the process of air flowing into the lungs during inspiration ( inhalation ) and out of the lungs during expiration  ( exhalation ). Air flows because of pressure differences between the atmosphere and the gases inside the lungs. Air, like other gases, flows from a region with higher pressure to a region with lower pressure. Muscular breathing movements and recoil of elastic tissues create the changes in pressure that result in ventilation.

67. Pulmonary ventilation involves three different pressures: Atmospheric pressure Intraalveolar (intrapulmonary) pressure Intrapleural pressure Atmospheric pressure is the pressure of the air outside the body. Intra alveolar pressure is the pressure inside the alveoli of the lungs. Intrapleural  pressure is the pressure within the pleural Capacity . These three pressures are responsible for pulmonary ventilation.

68. Inspiration Inspiration (inhalation) is the process of taking air into the lungs. It is the active phase of ventilation because it is the result of  muscle contraction. During inspiration, the diaphragm contracts and the thoracic cavity increases in volume. This decreases the intraalveolar pressure so that air flows into the lungs. Inspiration draws air into the lungs. Expiration Expiration (exhalation) is the process of letting air out of the lungs during the breathing cycle. During expiration, the relaxation of the diaphragm and elastic recoil of tissue decreases the thoracic volume and increases the intraalveolar pressure. Expiration pushes air out of the lungs.

69. Lung Capacity Lung capacity or total lung capacity (TLC) is the volume of air in the lungs upon the maximum effort of inspiration.   Among healthy adults, the average lung capacity is about 6 liters. Age, gender, body composition, and ethnicity are factors affecting the different ranges of lung capacity among individuals. TLC rapid increases from birth to adolescence and plateaus at around 25 years old. Males tend to have a greater TLC than females, while individuals with tall stature tend to have greater TLC than those with short stature.

70. CONT’D Clinicians can measure lung capacity by plethysmography, dilutional helium gas method, nitrogen gas washout method, or radiographically by a relatively new technique using by computed tomography (CT). Methodically, the TLC is calculated by measuring the lung capacities: inspiratory capacity (IC), functional residual capacity (FRC), and the vital capacity (VC). the lung capacities can be further divided into the following lung volumes: tidal volume (TV), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and the residual volume (RV). 

71. Self reading 1. Describe following lung capacities; inspiratory capacity (IC), functional residual capacity (FRC), and the vital capacity (VC). 2. Describe following lung volumes tidal volume (TV), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and the residual volume (RV). 

72. THANK YOU