LPN-C

1. LPN-C Unit Two Anatomy and Physiology of the Circulatory, Pulmonary, and Renal System

2. Circulatory, Pulmonary, and Renal System

3. The Heart

4. The Heart • Apex • Points forward, downward, and to the left at the 4th or 5th intercostal space • Base • “Broad” side that faces upward • The heart is 12cm long and 8cm wide at its base, and is 6cm thick • The heart weighs an average of 280g, and weighs more in men than in women • The layers of the heart are the pericardium, epicardium, myocardium, and endocardium

5. The Heart (cont’d) • The pericardium is a fibroserous sac that surrounds the heart and the roots of the great vessels; it provides the heart with physical protection and a barrier to infection • The epicardium is known as the visceral layer, and covers the entire heart and great vessels; the epicardium also forms the parietal layer that lines the pericardium • The myocardium is the muscular portion of the heart, which forms the walls of the atria and ventricles

6. The Heart (cont’d) • The endocardium is a thin, 3-layered membrane that lines the heart. • Inner layer = smooth endothelial cells supported by connective tissue • Middle layer = dense connective tissue • Outer layer = irregularly arranged connective cells • There are 4 chambers of the heart • Right and left atrium • Right and left ventricle

7. The Heart (cont’d) • The right atrium receives deoxygenated blood from the superior vena cava, inferior vena cava, and coronary sinus • The left atrium receives oxygenated blood from the pulmonary veins • Blood is emptied into the ventricles from the atria during diastole • The ventricles are thick, muscular walls that make up the bulk of the heart • A septum separates the ventricles and extends between the atria, dividing the heart into the right and left sides

9. The Heart (cont’d) • The great vessels of the heart are the superior vena cava, the inferior vena cava, the coronary sinus, pulmonary arteries, pulmonary veins, and the aorta • Superior Vena Cava • 2nd largest vein in the body • Returns deoxygenated blood from the upper half of the body to the right atrium • 2cm in diameter and 7cm long • Inferior Vena Cava • Returns deoxygenated blood to the heart from parts of the body below the diaphragm

10. The Heart (cont’d) • Coronary Sinus • Drains 5 coronary veins through a single semilunar valve • Coronary veins include the great cardiac vein, the small cardiac vein, the middle cardiac vein, the posterior vein of the left ventricle, and the oblique vein of the left atrium • Pulmonary Arteries • Deoxygenated blood leaves the right heart through the pulmonary artery, which divides into the left pulmonary artery (which enters the left lung) and the right pulmonary artery (which enters deoxygenated blood into the right lung)

11. The Heart (cont’d) • Pulmonary Veins • One of two pairs of large vessels that return oxygenated blood from each lung to the left atrium of the heart • Aorta • The main trunk of arterial circulation; consists of 4 parts • Ascending aorta • Arch of the aorta • Thoracic aorta • Abdominal aorta

12. The Heart (cont’d) Valves of the heart -- • Atrioventricular (AV) valves • Control the flow of blood between the atria and the ventricles • Form cusps: 2 on the left side of the heart (bicuspid, or mitral, valve) and 3 on the right side of the heart (tricuspid valve) • Supported by papillary muscles, which project from the walls of the ventricles, and chordae tendinae, which are chord-like structures that prevent the AV valves from reverting into the atria during systole

13. The Heart (cont’d) Valves of the heart -- • Semilunar valves • The aortic valve controls the flow of blood into the aorta • The pulmonic (or pulmonary) valve controls the flow of blood into the pulmonary artery

15. The Heart (cont’d) Blood supply of the heart – • 2 coronary arteries that arise from the coronary sinus, just above the aortic valve • The left coronary artery extends for 3½cm, then divides into the anterior descending artery and the circumflex branch • Anterior descending artery • Passes between the two ventricles • Forms diagonal branches, which supply the left ventricle • Forms perforating branches, which supply the anterior portion of the heart

16. The Heart (cont’d) Blood supply of the heart – • Circumflex branch • Passes through the left and moves posteriorly in the groove that separates the left atrium and ventricle • Forms branches that supply the left lateral wall of the left ventricle • The right coronary artery lies in the right AV groove, and its branches supply the right ventricle; the right coronary artery moves to the back of the heart, where it forms the posterior descending artery, which supplies the interventricular septum, AV node, and posterior papillary muscle

18. The Heart (cont’d) The conduction system – • Sinoatrial (SA) node • Pacemaker of the heart • Located in the right atrium, next to the superior vena cava • Impulses initiated at the SA node at an intrinsic rate of 60-100 beats per minute • Atrioventricular (AV) node • Connects the two conduction systems • Atrial activity • Ventricular activity • Provides a “one-way” conduction between the atria and ventricles

19. The Heart (cont’d) The conduction system – • Bundle of His (AV Bundle) • Causes a delay in conduction that provides a mechanical advantage by allowing the atria to complete their ejection of blood before ventricular contraction begins • Penetrates into the ventricles and divides into the right and left bundle branches • The bundle branches subdivide into the Purkinje fibers, which branch out and supply the outer walls of the ventricles • The Purkinje system supplies rapid conduction and excitation of the right and left ventricles

21. The Heart (cont’d) The physiology of the cardiac cycle – • The cardiac cycle refers to the events related to the flow of blood that occur from the beginning of one heartbeat to the beginning of the next; used to describe the pumping action of the heart • Isometric ventricular relaxation = both ventricles are relaxed and both AV and semilunar valves are closed • Ventricular filling = AV valves open and blood fills the ventricles • Ventricular contraction = blood is forced out of the ventricles

22. The Heart (cont’d) The physiology of the cardiac cycle – • Systole = contraction of the ventricles • Atrial systole is the contraction of the atria of the heart that precedes ventricular contraction by a fraction of a second • Ventricular systole is the contraction of the ventricles, which begins with the closure of the AV valves • Diastole = relaxation of the ventricles during which they are filling with blood • Ventricular diastole marks the closure of the semilunar valves; this constitutes ventricular filling

24. The Heart (cont’d) The physiology of cardiac output – • Cardiac output = the output of blood by the heart per minute; determined by the stroke volume and the heart rate • Heart rate = the frequency with which blood is ejected from the heart; as the heart rate increases, cardiac output tends to increase • Stroke volume = the amount of blood pumped by the left ventricle of the heart in one contraction; this is not all the blood contained in the ventricle

25. The Heart (cont’d) The physiology of cardiac output – • Preload = the amount of blood that the heart must pump with each beat at the end of diastole; measured by central venous pressure or “pulmonary wedge pressure” • Afterload = the pressure or tension that impedes the flow of blood out of the heart • Cardiac contractility = the ability of muscle tissue to contract when its thick (myosin) and thin (actin) filaments slide past each other

26. The Heart (cont’d) Heart rate regulation – • Autonomic regulation of cardiac function • Parasympathetic nervous system • Regulates heart rate through the vagus nerve: increased vagal activity produces a slowing of the heart rate • Acts to conserve energy, promote bowel/bladder elimination, pupil contraction, etc • Sympathetic nervous system • Excitatory influence on heart rate and contractility • Increases blood pressure and blood sugar, dilates bronchioles and pupils (i.e. “fight-or-flight” response)

27. The Heart (cont’d) Heart rate regulation – • Electrolytes • Sodium • Due to fluid retention in the blood vessels from high levels of sodium (hypernatremia), the heart has to work harder to pump blood to the body • Potassium • Both hypo- and hyperkalemia can have profound effects on cardiac contractility • High levels of serum potassium can result in tachycardia, then bradycardia, and death • Low levels of serum potassium can result in bradycardia and death • Important electrolyte for patients on diuretics or heart medications

28. The Heart (cont’d) Heart rate regulation – • Electrolytes • Calcium • Necessary for muscle contractility, cardiac function, neural transmission, and blood clotting • Body Temperature • Hyperthermia can lead to tachycardia, cardiac dysrhythmias, labile blood pressure, postural instability • Hypothermia can result in a gradual decline in heart rate and cardiac output • Blood pressure initially rises, then falls • Dysrhythmias • Ventricular fibrillation

29. The Heart (cont’d) Heart rate regulation – • Emotions: the average person’s heart rate increases with any intense emotion, including anger, fear, happiness, and anxiety • Gender: a woman’s heart rate is typically higher than that of a man because the female heart is smaller, requiring more beats to pump the same amount of blood • Age: the heart rate decreases with age; the average heart rate is 60-80 beats per minute, whereas an infant’s is much faster and an elderly person’s is slower

30. The Heart (cont’d) Veins and arteries – What is the Difference? • Arteries take blood away from the heart, whereas veins bring blood back to the heart; generally speaking, blood found in arteries is oxygenated, and blood found in veins is deoxygenated; the exception is the pulmonary arteries, which carry deoxygenated blood from the heart to the lungs, and the pulmonary veins, which carry oxygenated blood from the lungs to the heart

31. The Heart (cont’d) Veins and arteries – • Arteries • Tough, elastic tubes that divide into smaller vessels as they move away from the heart • Must be able to withstand immense pressure as they receive blood directly from the heart • The largest artery in the body is the aorta, which originates from the heart and branches out into smaller arteries • The smallest arteries are termed arterioles • Intra-arterial pressure is the force applied against the walls of the arteries as the heart pumps blood through the body

32. The Heart (cont’d) Veins and arteries – • Veins • Elastic vessels that transport blood to the heart • The smallest veins in the body are called venules • Venules receive blood from the arteries via arterioles and capillaries, then branch into larger veins which carry the blood to the largest vein in the body, the vena cava • The vena cava transports blood directly to the right atrium of the heart • Intravenous pressure is the pressure in the veins and is difficult to measure noninvasively

33. Veins Arteries

34. The Heart (cont’d) Veins and arteries – • Venous and arterial walls • The walls of both the arteries and the veins consist of 3 layers, the tunica adventitia, tunica media, and tunica intima • In arteries, the tunica intima has an elastic membrane lining • In most veins, the tunica intima contains valves, which are flap-like structures that allow blood to flow in only one direction • Capillaries are located within the tissues of the body and transport blood from the arterioles to the venules; walls are very thin

36. Identify the location of veins in the upper torso commonly used for central line and peripheral line insertion:JugularSubclavianSuperior Vena CavaBasilicCephalicDorsal Metacarpal

39. Digital dorsal vein • Dorsal metacarpal vein • Dorsal venous network • Cephalic vein • Basilic vein

40. The Lungs

41. The Lungs • The respiratory system consists of air passages where gas exchange takes place • Air passages are divided into conducting airways and respiratory tissues • Conducting airways are passages through which air moves as it passes into and out of the lungs; consists of the mouth, nasal passages, nasopharynx, larynx, and the tracheobronchial tree (trachea, bronchi, and bronchioles) • Respiratory tissues are the functional unit of the lungs; this is where gas exchange actually occurs; consists of the respiratory bronchioles, alveoli, and pulmonary capillaries

42. The Lungs (cont’d) Conducting airways -- • Air is warmed, filtered, and humidified as it passes through the conducting airways • The trachea divides to form the right and left primary bronchi • The primary bronchi divide into secondary (or lobular) bronchi, which supply each of the lobes of the lung • The secondary bronchi branch to form smaller bronchi, which are named terminal bronchioles; these are the smallest of the conducting airways

43. The Lungs (cont’d) Respiratory tissues -- • The lungs are the functional structures of the respiratory system; they activate substances such as bradykinin, which is a potent vasodilator, and convert angiotensin 1 to angiotensin 2 (which is a potent vasoconstrictor) • If the lungs are the functional structures of the respiratory system, then lobules are the functional units of the lungs; lobules consist of respiratory bronchioles, alveoli, and pulmonary capillaries

44. The Lungs (cont’d) Respiratory tissues -- • Oxygen from the alveoli diffuses across the alveolar capillary membrane into the blood; carbon dioxide from the blood diffuses into the alveoli

45. The Lungs (cont’d) Inhalation and exhalation -- • Inhalation (inspiration): the diaphragm, assisted by external intercostal muscles, causes the size of the chest cavity to increase; intrathoracic pressure becomes more negative; air is drawn into the lungs • Exhalation (expiration): occurs as the elastic components of the chest wall and lung structures that were stretched during inspiration recoil, which causes the size of the chest cavity to decrease and the intrathoracic pressure to increase

46. The Lungs (cont’d) Inhalation and exhalation -- • The act of breathing normally is effortless and does not require conscious thought • Normal rate of respiration is usually between 16-18 breaths per minute, which is approximately 1 breath for every 4 heartbeats • In normal breathing, expiration is largely passive, and is accomplished within 4-6 seconds • Movements are smooth, with equal expansion bilaterally

47. The Lungs (cont’d) Inhalation and exhalation -- • Gender plays a role in the act of breathing • In men, respiratory movements are diaphragmatic • In women, there is greater movement of the intercostal muscles • When breathing becomes labored, the accessory muscles of the neck are used, and nostrils may flare • The suffix “pnea” refers to breathing • Tachypnea = rapid breathing • Hyperpnea = increased rate/depth of breathing

48. The Lungs (cont’d) Inhalation and exhalation – • Hyperventilation causes excessive intake of oxygen and excessive elimination of carbon dioxide; leads to dizziness, faintness, and numbness to the fingers and toes • Hypoventilation is ventilation that is inadequate for alveolar-capillary exchange of carbon dioxide and oxygen; causes increased PaCO2 and hypoxia

49. The Lungs (cont’d) Breath sounds -- • “Normal” breath sounds = bronchial sounds, bronchiovesicular sounds, and vesicular sounds • Abnormal (or adventitious) breath sounds are those that can not be categorized as “normal” • Stridor = intense, continuous monophonic wheezes that are accentuated during inspiration; stridor can often be heard without a stethoscope; indicates upper airway obstruction

50. The Lungs (cont’d) Breath sounds – • Abnormal breath sounds – • Wheezes (or rhonchi) = continuous musical tones most commonly heard at the end of inspiration or early expiration; indicate narrowed airway due to a thickening of reactive airway walls, or collapse of airways due to pressure from surrounding pulmonary disease • Pleural friction rub = low-pitched, grating or creaking sound that occurs when inflamed pleural surfaces rub together during respiration; more often heard on inspiration than expiration; may indicate pleural effusion, pneumothorax, bacterial pneumonia