Anatomy review

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=90 BGCOLOR="#006699" TEXT="#080000" background="044fd5a3.jpg"> <div> <FONT SIZE="5" COLOR="#000000" FACE="Arial" ><B>Imene Benayache. MD</B></FONT><B>    </B><B> |     </B><A HREF="index.htm" TARGET="_top" TITLE="Imene Benayache. 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The respiratory or pulmonary system.</div> <bR> <div> A/. Anatomy review.</div> <bR> <div> Ø   The respiratory system includes:</div> <bR> <div> ·       The upper respiratory tract.</div> <bR> <div> ·       The lower respiratory tract.</div> <bR> <div> ·       The lungs.</div> <bR> <div> ·       A neuromuscular system.</div> <bR> <div> Ø   The upper respiratory system is composed of:</div> <bR> <div> ·       Nasal cavity (nose) and the mouth</div> <bR> <div> ·       Pharynx (nasopharynx) and (oropharynx).</div> <bR> <div> ·       Larynx.</div> <bR> <div>  </div> <bR> <div> Ø   The lower respiratory system is composed of:</div> <bR> <div> ·       Trachea</div> <bR> <div> ·       Main bronchi (one to the left and one to the right) ® secondary or lobular bronchi ® tertiary bronchi.</div> <bR> <div> ·       Bronchioles ® terminal ® respiratory bronchioles ® alveolar sacs ® alveoli.</div> <bR> <div>  </div> <bR> <div> Ø    Lungs: consist of 2 lobes on the left and 3 on the right.</div> <bR> <div>  </div> <bR> <div> Ø    Location: in the thorax cavity, composed of the ribs (12 pairs), supported in the back by spine and in front by the sternum.</div> <bR> <div> Ø    Each lungs lies within its own side of the thorax cavity and is surrounded by the visceral layer of the pleura.</div> <bR> <div>  </div> <bR> <div>  </div> <bR> <div>  </div> <bR> <div> Ø    From outside to the inside:</div> <bR> <div> ·       Parietal pleura</div> <bR> <div> ·       Pleural cavity in between</div> <bR> <div> ·       Visceral pleura, which is adherent to surface of the lungs and extends into the fissures of the lungs.</div> <bR> <div> Ø    Each lobe has a main bronchus, one pulmonary artery and 2 pulmonary veins.</div> <bR> <div> v   If trauma or ribs fracture, a pneumothorax or hemothorax occur in the cavity.</div> <bR> <div>  </div> <bR> <div> Ø    Neuromuscular system:</div> <bR> <div> Ø    Consists of the respiratory center in the brain (medulla), the nerves to the muscles of respiration (phrenic nerve) and the muscles of respiration.</div> <bR> <div> Ø    Muscles of respiration:</div> <bR> <div> Diaphragm: is a dome-shaped sheet of muscle separating the thorax and abdominal cavity. Is attached to the margin of the lower ribs, which extends from front to back. “Is the major muscle of respiration”.</div> <bR> <div> ·       The external intercostal muscles: fibers originate from an upper rib and insert on a lower rib more anteriorly.</div> <bR> <div> ·       Accessory muscles: include the sternomastoid and other strap of the neck.</div> <bR> <div>  </div> <bR> <div> v   N.B:</div> <bR> <div> v   Alveoli: are millions of air sacs that hold CO2 and O2 and are lined by a membrane. On the other side of the membrane is a fine network of capillaries.</div> <bR> <div> v   The pulmonary arteries: carry blood with low O2 and high in CO2 from the right heart.</div> <bR> <div> v   The pulmonary veins: carry blood with high O2 to the left of the heart.</div> <bR> <div>  </div> <bR> <div> B/. Physiology review.</div> <bR> <div> Ø    The primary role of the respiratory system is to maintain a constant internal environment by providing O2 for metabolic needs and excreting CO2.</div> <bR> <div> ·       External respiration: involves the exchange of gas between the environment and the lungs, the transfer of gas across the respiratoy membrane, and the transport of gas by the blood to and from the body cells.</div> <bR> <div> ·       Internal respiration: is the intracellular O2 utilization through metabolic transformation.</div> <bR> <div>  </div> <bR> <div> Ø    The secondary role is to balance the acid and base equilibrium.</div> <bR> <div> Ø    The stimulus to breath comes from the respiratory center the (medulla), which travels along the spinal cord either voluntary or involuntary pathway, but the primary stimulus for altering the depth and rate of breaths in the level of CO2 in the arterial blood and pH</div> <bR> <div>  </div> <bR> <div> Ø    The breathing rate and depth are increased, until the level of CO2 falls, then ® breathing rate slows.</div> <bR> <div>  </div> <bR> <div> Ø    At the level of the alveoli, O2 from the air passes into the circulation through the alveolar and capillary walls, and CO2 passes in the opposite direction.</div> <bR> <div>  </div> <bR> <div> Ø    Composition of the air: is a mixture of gases, primarily nitrogen (N2) and O2, with a variable amount of water vapor, and a small amount of CO2 and inert gases.</div> <bR> <div>  </div> <bR> <div> Ø    Dry atmospheric air contain: 79% N2 and 21% O2.</div> <bR> <div>  </div> <bR> <div> Ø    Because only ¼ of O2 in the inhaled air is taken up by the RBC (hemoglobin) in the lungs during respiration.</div> <bR> <div>  </div> <bR> <div> Ø    Exhaled air contains 16% of O2, 5% of CO2 and some vapor H2O.</div> <bR> <div>  </div> <bR> <div> Ø    In CPR, the exhaled air of rescue breaths contains enough O2 to support the life of the victim.</div> <bR> <div>  </div> <bR> <div> Ø    Inspiration: is an active process. As the intercostal muscles contract, it descends toward the abdominal cavity.</div> <bR> <div>  </div> <bR> <div> ·       The lungs expand and the pressure within the lungs becomes lower than the outside of the thorax</div> <bR> <div> ·       The difference in pressure draws air into the airways and the lungs.</div> <bR> <div>  </div> <bR> <div> Ø    Expiration: is a passive process. As the muscles relax, the ribs descend and the diaphragm rises, decreasing the capacity of the thorax or chest cavity.</div> <bR> <div> Ø    The elastic lung passively becomes smaller, and the air inside the lung moves out.</div> <bR> <div>  </div> <bR> <div>  </div> <bR> <div>  </div> <bR> <div>  </div> <bR> <div>  </div> <bR> <div>  </div> <bR> <div> II/. The cardiovascular system.</div> <bR> <div> A/. Anatomy review.</div> <bR> <div> Ø   The circulatory system includes:</div> <bR> <div> ·       The heart</div> <bR> <div> ·       Arteries</div> <bR> <div> ·       Capillaries</div> <bR> <div> ·       Veins.</div> <bR> <div>  </div> <bR> <div> Ø    The heart: is a muscular (myocardium) pump that propels blood through the circulatory system. There are 2 circulatory loops:</div> <bR> <div>  </div> <bR> <div> ·       Pulmonary circulation: blood is pumped from the right side of the heart through the lungs to the left side of the heart.</div> <bR> <div> ·       Systemic circulation: blood is pumped from the left side of the heart through the tissues of the body and returned to the right side of the heart.</div> <bR> <div>  </div> <bR> <div> Ø    Location: middle mediastinum.</div> <bR> <div>  </div> <bR> <div> Ø    Shape: hollow chambers.</div> <bR> <div>  </div> <bR> <div> Ø    From outside to the inside of the heart:</div> <bR> <div> ·       Epicardium or visceral pericardium, surrounded by a space the pericardial cavity, enclosed by a fibrous sac the pericardium (parietal pericardium).</div> <bR> <div> ·       Myocardium</div> <bR> <div> ·       Endocardium, which is the tunica intima of the heart.</div> <bR> <div>  </div> <bR> <div> v   Trauma to the anterior chest wall can result in bleeding into the pericardial cavity and cardiac tamponade happen.</div> <bR> <div>  </div> <bR> <div> Ø    Coronary circulation: supplies the myocardium with blood.</div> <bR> <div> ·       Right and left coronary arteries begin the sinuses behind the right and left semilunar cups of the aortic valve. They distribute blood in a large part to their own half of the heart.</div> <bR> <div> ·       Blood flow in the coronary arteries is maximal during diastole and minimal during systole.</div> <bR> <div>  </div> <bR> <div> B/. Physiology of the heart.</div> <bR> <div> Ø   Heart: is a double pump in series (right and left) that are connected by the pulmonary and the systemic circulation.</div> <bR> <div> ·       It provides the driving force for the cardiovascular system.</div> <bR> <div> ·       Each side is equipped with 2 valves that maintain a one-way blood flow.</div> <bR> <div> ·       The principal role is to pump blood to the lungs and the entire body.</div> <bR> <div>  </div> <bR> <div> Ø   Arteries: serve as distribution channels to the organs.</div> <bR> <div> Ø   Capillaries: serve as exchange region.</div> <bR> <div> Ø   Veins: serve as blood reservoirs and collect the blood to return it to the heart.</div> <bR> <div> Ø   All body cells require O2 continuously to carry out normal function. CO2 is produced as a waste product and is eliminated through the lungs.</div> <bR> <div> Ø   Heart pumps about 5-6 L each minute at rest (5l/mn), which is the cardiac output {CO = SV X HR} =70 ml of blood and a normal HR = 70-75 b/mn.</div> <bR> <div> Ø   During exercise, the heart may require to pump 4-7 times this amount.</div> <bR> <div> Ø   HR is under sympathetic efferent activity ®  HR, and parasympathetic (vagal) efferent impulses ¯ HR.</div> <bR> <div> Ø   Each cardiac muscle contraction or heartbeat is initiated by an electrical impulse that arises from the pacemaker, which is specialized conducting tissue of the heart.</div> <bR> <div> Ø   It is the sinoatrial (SA) node located near the junction of the superior vena cava and the right atrium.</div> <bR> <div> Ø   The depolarization of the heart follow this pathway:</div> <bR> <div>  </div> <bR> <div>  </div> <bR> <div> SA node</div> <bR> <div>  </div> <bR> <div>  </div> <bR> <div> Right atrium                                      Left atrium</div> <bR> <div>  </div> <bR> <div>                                 AV node</div> <bR> <div>  </div> <bR> <div>                                 Bundle of His</div> <bR> <div>  </div> <bR> <div>  </div> <bR> <div>                                 R and LBB</div> <bR> <div>  </div> <bR> <div>                                 Purkinje fibers</div> <bR> <div>  </div> <bR> <div>                                 Ventricular muscle</div> <bR> <div>  </div> <bR> <div>  </div> <bR> <div> Ø   HR can be altered by nerve impulses from the brain (ANS) and rise in temperature, thyroid hormones, and other substances that influence the pace maker and the conduction system.</div> <bR> <div>  </div> </td> </tr></table></body>