Anaphy-Lecture-Week-5 PDF

CIRCULATORY SYSTEM Blood - contributes to homeostasis by transporting oxygen, carbon dioxide, nutrients, and hormones to and from PHYSICAL CHARACTERISTIC OF BLOOD your body’s cells. - It also helps regulate body pH and Blood temperat...

CIRCULATORY SYSTEM Blood - contributes to homeostasis by transporting oxygen, carbon dioxide, nutrients, and hormones to and from PHYSICAL CHARACTERISTIC OF BLOOD your body’s cells. - It also helps regulate body pH and Blood temperature and provides protection - Is denser and more viscous (thicker) than against disease through phagocytosis water and feels slightly sticky and the production of antibodies. - Blood temperature: is 38° (100.4°F), about - is a liquid connective tissue that 1°C higher than oral or rectal body temperature consists of cells surrounded by a liquid - Slightly alkaline pH ranging from 7.35 to 7.45 extracellular matrix (blood plasma) (average = 7.4) - The color of blood varies with its oxygen Interstitial Fluid content - is the fluid that bathes body cells and is BRIGHT RED – if saturated with constantly renewed by the blood oxygen DARK RED - if unsaturated with oxygen FUNCTIONS OF BLOOD FORMED ELEMENTS OF BLOOD Transportation – blood transports inhaled oxygen from the lungs to the cells of the Red blood cells (RBCs) or erythrocytes body and carbon dioxide from the body cells to - transport oxygen from the lungs to body cells the lungs for exhalation. and deliver carbon dioxide from body cells to the lungs. (lives until 120 days only, produced Regulation – blood helps regulate pH using in the bone marrow) buffers (chemicals that convert strong acids or bases into weak ones). It also helps adjust White blood cells (WBCs) or leukocytes body temperature through the heat-absorbing - protect the body from invading pathogens and and coolant properties of the water in blood other foreign substances. These are several plasma and its variable rate of flow through the types of WBCs: neutrophils, basophils, skin, where excess heat can be loss from the eosinophils, monocytes, and lymphocytes blood to the environment. - Lymphocytes are further subdivided into B lymphocytes (B cells), T lymphocytes (T Protection – blood can clot (become gel-like), cells), and natural killer (NK) cells. which protects against its excessive loss from the cardiovascular system after an Platelets injury. In addition, its white blood cells protect - the final type of formed element, are against disease by carrying on phagocytosis. fragments of cells that do not have a nucleus, release chemicals that promote vascular - Heart pumps more vigorously when you are spasm and blood clotting active. Actual blood volume your heart pumps in a single day is much larger ANATOMY OF THE HEART Location of the Heart Heart - relatively small, roughly the same size (but not the same shape) as your closed fist, rests on the diaphragm, near the midline of the thoracic cavity - Long axis: about 12 cm (5 in) - Width: 9 cm (3.5 in) at its broadest point - Depth: 6 cm (2.5 in) anterior to posterior - Average mass: 250 g (8 oz) in adult females and 300 g (10 oz) in adult males - heart lies in the MEDIASTINUM, about two- thirds of the mass of the heart lies to the left of the body’s midline Apex - pointed part, formed by the tip of the left ventricle (a lower chamber of the heart). It is directed anteriorly, inferiorly, and to the left. HEART Base – is opposite the apex and is its posterior - contributes to homeostasis by pumping aspect. It is formed by the atria (upper blood through blood vessels to the tissues of chamber) of the heart, mostly the left atrium the body to deliver oxygen and nutrients and remove wastes - The heart beats about 100,000 times every day, which adds up to about 35 million beats in a year, and approximately 2.5 billion times in an average lifetime - Even while you are sleeping, your heart pumps 30 times its own weight each minute (about 5 liters) to the lungs and the same volume to the rest of the body. - At this rate, your heart pumps more than about 14,000 liters (3600 gal) of blood in a day, or 5 million liters (1.3 million gal) in a year  SEROUS PERICARDIUM Parietal Layer of Serous Pericardium - Outermost layer that lines the inside of the fibrous pericardium Visceral Layer of Serous Pericardium/Epicardium - innermost layer of the heart wall and adheres tightly to the surface of the heart. Pericardial Fluid - is a thin film of a few milliliters of lubricating serous fluid - a slippery secretion of pericardial cells that reduces friction between the layers of the serous pericardium as the heart moves. Pericardial Cavity - space that contains the few milliliters of pericardial fluid PERICARDIUM - membrane that surrounds and protects the heart and confines its position in the mediastinum, while allowing sufficient freedom of movement for vigorous and rapid contraction. The pericardium consists of two main parts: 1. Fibrous Pericardium - superficial, and is composed of tough, inelastic, dense irregular connective tissue. - prevents overstretching of the heart, provides protection, and anchors the heart in the mediastinum. 2. Serous Pericardium - deeper, thinner, more delicate LAYERS OF THE HEART WALL mesothelial membrane that forms a double layer around the heart 1. Epicardium (external layer) – imparts a smooth, slippery texture to the outermost surface of the heart that contains blood vessels, lymphatics, and nerves that supply the myocardium  A. Visceral Layer of the Serous Pericardium – thin, transparent outer layers of the heart wall that is composed of Auricle mesothelium - wrinkled pouchlike structure on the anterior Beneath the mesothelium is a variable surface of atrium. It increases the capacity of layer of delicate fibroelastic tissue and an atrium so that it can hold a greater volume adipose tissue. of blood. B. Adipose Tissue – predominates and Sulci becomes thickest over the ventricular - series of groove on the surface of the heart, surfaces, where it houses the major that contain coronary blood vessels and a coronary and cardiac vessels of the heart. variable amount of fat - Deep CORONARY SULCUS (coron = 2. Myocardium (middle layer) resembling a crown) encircles most of the - responsible for the pumping action of the heart and marks the external boundary heart and is composed of cardiac muscle between the superior atria and inferior tissue. It makes up approximately 95% of the ventricles heart wall. - cardiac muscle fibers are organized in - Anterior Interventricular Sulcus – is a bundles that swirl diagonally around the shallow groove on the anterior surface of the heart and generate the strong pumping heart that marks the external boundary actions of the heart between the right and left ventricles on the anterior aspect of the heart 3. Endocardium (innermost layer) - is a thin layer of endothelium overlying a thin - Posterior Interventricular Sulcus – marks layer of connective tissue. the external boundary between the - it provides a smooth lining for the ventricles on the posterior aspect of the chambers of the heart and covers the valves heart of the heart The smooth endothelial lining minimizes the surface friction as blood passes through the heart. CHAMBERS OF THE HEART Atria/Atrium - 2 superior receiving chambers - The paired atria receive blood from blood vessels turning blood to the heart, called veins, while the ventricles eject the blood from the heart into blood vessels called arteries Ventricle - 2 inferior pumping chambers RIGHT ATRIUM RIGHT VENTRICLE forms the right surface of the heart and receives blood from three veins: o the superior vena cava, inferior vena cava, and coronary sinus is about 4–5 mm (0.16–0.2 in.) in average thickness and forms most of about 2–3 mm (0.08–0.12 in.) in the anterior surface of the heart. average thickness. TRABECULAE CARNEAE – series of The anterior and posterior walls of the ridges formed by raised bundles of right atrium are very different. cardiac muscle fibers inside the right o inside of the posterior wall is ventricle. smooth; o inside of the anterior wall is rough CORDAE TENDINAE – tendon-like due to the presence of muscular cords where cusps of right AV valve are ridges called PECTINATE MUSCLES connected. which also extend into the auricle PAPILLARY MUSCLES - cone-shaped INTERATRIAL SEPTUM – thin partition in trabeculae carneae where cordae between the right atrium and left atrium tendinae is connected. FOSSA OVALIS - an oval depression on INTERVENTRICULAR SEPTUM – the septum, the remnant of the internal partition that separates the foramen ovale, an opening in the right ventricle from the left ventricle interatrial septum of the fetal heart that normally closes soon after birth RIGHT ATRIOVENTRICULAR VALVE/tricuspid valve – where blood passes from the right atrium into the right ventricle (consists of 3 cusps/leaflets) The valves of the heart are composed of dense connective tissue covered by endocardium.  branch from the ascending aorta and carry blood to the heart wall. The remainder of the blood passes into the AORTIC ARCH (thoracic aorta) and DESCENDING AORTA (abdominal aorta). Branches of the aortic arch and descending aorta carry blood throughout the body. During fetal life, a temporary blood vessel, called the DUCTUS ARTERIOSUS, shunts blood from the LEFT ATRIUM pulmonary trunk into the aorta. Hence, only a small amount of blood enters the nonfunctioning fetal lungs The ductus arteriosus normally closes shortly after birth, leaving a remnant known as the LIGAMENTUM is about the same thickness as the right ARTERIOSUM which connects the atrium and forms most of the base of aortic arch and pulmonary trunk the heart It receives blood from the lungs through four pulmonary veins. anterior and posterior internal wall of left atrium is smooth. Blood passes from the left atrium into the left ventricle through the LEFT ATRIOVENTRICULAR VALVE (bicuspid or mitral) - has two cusps. LEFT VENTRICLE HEART VALVES is the thickest chamber of the heart, ATRIOVENTRICULAR VALVE (AV Valve) averaging 10–15 mm (0.4–0.6 in.), and - valves located between an atrium and forms the apex of the heart a ventricle Like the right ventricle, the left ventricle o MITRAL/BICUSPID VALVE – between contains trabeculae carneae and has left atrium and left ventricle chordae tendineae that anchor the o TRICUSPID VALVE – between right cusps of the bicuspid valve to papillary atrium and right ventricle muscles. SEMILUNAR VALVE (SL Valve) - aortic Some of the blood in the aorta flows and pulmonary valves, because they into the CORONARY ARTERIES, which  are made up of three crescent moon– o INFERIOR (posterior) shaped cusps INTERVENTRICULAR ARTERY - follows the posterior interventricular sulcus and supplies the walls of the two ventricles with oxygenated blood. o MARGINAL BRANCH - beyond the coronary sulcus runs along the right margin of the heart and transports oxygenated blood to the wall of the right ventricle. CORONARY CIRCULATION - Nutrients are not able to diffuse quickly enough from blood in the chambers of the heart to supply all layers of cells that make up the heart wall. - For this reason, the myocardium has its own network of blood vessels, the CORONARY CIRCULATION or cardiac circulation (coron- = crown). - The CORONARY ARTERIES branch from the ascending aorta and encircle the heart as a LEFT CORONARY ARTERY - passes crown encircles the head inferior to the left auricle and divides - While the heart is contracting, little blood into: flows in the coronary arteries because they are o CIRCUMFLEX ARTERY - lies in the squeezed shut. coronary sulcus and distributes - When the heart relaxes, however, the high oxygenated blood to the walls of pressure of blood in the aorta propels blood the left ventricle and left atrium. through the coronary arteries, into capillaries, o ANTERIOR INTERVENTRICULAR and then into CORONARY VEINS ARTERY or left anterior descending (LAD) artery - is in the anterior CORONARY ARTERIES interventricular sulcus and supplies RIGHT CORONARY ARTERY - supplies oxygenated blood to the walls of small branches (atrial branches) to the both ventricles. right atrium. It continues inferior to the right auricle and ultimately divides into: CORONORY VEINS After blood passes through the arteries of the coronary circulation, it flows into capillaries, where it delivers oxygen  and nutrients to the heart muscle and PHYSIOLOGIC PROPERTIES OF THE HEART collects carbon dioxide and waste, and then moves into CORONARY Electrical properties: VEINS. Excitability = bathmotropy Most of the deoxygenated blood from Automaticity chronotropy the myocardium drains into a large Conductivity = dromotropy vascular sinus in the coronary sulcus Mechanical properties: on the posterior surface of the heart, Contractility = inotropy = systole called the CORONARY SINUS. Distensibility = lusitropy = The deoxygenated blood in the diastole coronary sinus empties into the right atrium. The principal tributaries carrying blood into the coronary sinus are the following: GREAT CARDIAC VEIN in the anterior interventricular sulcus, which drains the areas of the heart supplied by the left coronary artery (left and right ventricles and left atrium) MIDDLE CARDIAC VEIN in the posterior interventricular sulcus, which drains the areas supplied by the inferior interventricular artery of the right CARDIAC TISSUES coronary artery (left and right ventricles) SMALL CARDIAC VEIN in the coronary 1. Myocytes sulcus, which drains the right atrium and right ventricle ANTERIOR CARDIAC VEIN, which drain the right ventricle and open directly into the right atrium 2. SPECIALIZED TISSUES Excitability - ability of a cell to respond to external stimulus by depolarization - ability of cardiac cells to initiate AP in response to inward depolarizing current THE HEART: CONDUCTION SYSTEM Intrinsic conduction system (nodal system) 1% of cardiac cells are self-excitable Heart muscle cells contract, without nerve impulses, in a regular, continuous way However, these cells are synchronized by the sinoatrial (SA) node, or pacemaker, located in the wall of the right atrium. Sinoatrial node- Pacemaker o 70-8- bpm Atrioventricular node o 40-60 bpm Atrioventricular bundle Bundle branches Purkinje fibers o 20-40 BPM  THE HEART: REGULATION OF HEART RATE Starling’s law of the heart – more stretch = stronger contraction Changing heart rate is the most common way to change cardiac output ELECTROCARDIOGRAM - Recording of electrical changes that occur in the myocardium: P wave – atrial depolarization QRS wave – ventricular depolarization CONTROL T wave – ventricular repolarization While the SA node sets the tempo for the entire heat, it is influenced by a variety of physiological cues. - Two sets of nerves affect heart rate with one set speeding up the pacemaker and the other set slowing it down. - The pacemaker is also influenced by hormones. o For example, epinephrine from the adrenal glands increases heart rate. - The rate of impulse increases in response to increases in body temperature and with exercise. BLOOD VESSELS - contribute to homeostasis by providing the structures for the flow of blood to and from THE HEART: CARDIAC CYCLE the heart and the exchange of nutrients and - Atria contract simultaneously wastes in tissues - Atria relax, then ventricles contract - they also play an important role in adjusting - Systole = contraction the velocity and volume of blood flow. - Diastole = relaxation - The five main types of blood vessels are 1. Arteries THE HEART: CARDIAC OUTPUT 2. Arterioles Cardiac output (CO) 3. Capillaries o CO = (heart rate [HR] x (stroke 4. Venules volume [SV]) 5. Veins - 5.25 L/min up to 35 L/min Stroke volume o The average stroke volume for a FIVE MAIN TYPES OF BLOOD VESSELS human is about 75 mL 1. Artery – carries oxygenated blood away Heart rate from the heart to other organs o Varies but at rest is 70 bpm 2. Arterioles – smaller artery that branched off 2. Muscular Artery/medium sized arteries from medium sized arteries - so called because their tunica media 3. Capillaries/Blood Capillaries – smallest BV, contains more smooth muscle and fewer numerous tiny vessels where arterioles elastic fibers than elastic arteries branched off as it enters a tissue. - due to thick walls, they are capable of The thin walls of capillaries allow the greater vasoconstriction and vasodilation exchange of substances between the adjust the rate of blood flow blood and body tissues. - because of the reduced amount of elastic 4. Venules – small veins formed by a group of tissue in the walls of muscular arteries, these capillaries reunited within a tissue vessels do not have the ability to recoil and 5. Veins – merged venules, larger blood vessels help propel the blood like the elastic arteries that convey deoxygenated blood from the o Femoral artery and Axillary artery tissues back to the heart Distributing Arteries – muscular artery continues to branch and ultimately distribute blood to each of the various organs o Brachial artery, Radial artery ARTERIOLES meaning small arteries, an abundant microscopic vessel that regulate the flow of blood into the capillary ARTERY networks of the body’s tissues - The wall of an artery has the three layers of a METARTERIOLE – terminal end of the typical blood vessel but has a thick muscular- arteriole, tapers toward the capillary to-elastic tunica media. junction - Due to their plentiful elastic fibers, arteries At the metarteriole junction, the distal- normally have high compliance, which means most muscle cell forms the that their walls stretch easily or expand PRECAPILLARY SPHINCTER which without tearing in response to a small monitors the blood flow into the increase in pressure. capillary; the other muscle cells in the arteriole regulate the resistance 1. Elastic Artery/conducting arteries – largest (opposition) to blood flow in the body, perform an important function - Aka RESISTANCE VESSEL – because it PRESSURE RESERVOIR (help propel plays a key role in regulating blood blood onward while the ventricles are relaxing) flow from arteries into capillaries by o Aorta and Pulmonary trunk regulating resistance, the opposition  to blood flow due to friction between Postcapillary venules – initially receive blood and the walls of blood vessels blood from capillaries Muscular venules - (50 μm to 200 μm) have thicker walls across which exchanges with the interstitial fluid can no longer occur CAPILLARIES VEINS - very thin walls relative to their total diameter (range in size from 0.5 mm in diameter for small veins to 3 cm in the large superior and interior - smallest of blood vessels, have diameters of venae cava entering the heart) 5-10 μm and form the U-turns that connect the - many veins, especially in the limbs, also arterial outflow to the venous return contain valves (thin folds of tunica intima that - primary function: MICTURATON (exchange of form flaplike cusps) substances between the blood and interstitial - The VALVE CUSPS projects into the lumen, fluid) pointing toward the heart that aids in venous return by preventing the backflow of blood. VENULES smallest venules, measuring 10 μm to 50 μm in diameter have thin walls that do not readily maintain their shape, drains the capillary blood and begin the return flow of blood back toward the heart Function: significant sites of exchange of nutrients and wastes and white blood cell emigration, and for this reason form part of the microcirculatory exchange unit along with the capillaries  SUMMARY OF FUNCTION - Exchange of nutrients and gases occurs across the thin capillary walls. - Blood unloads O2 (oxygen) and picks up CO2 (carbon dioxide). - In most cases, blood flows through only one capillary and then enters a systemic venule. - Venules carry deoxygenated (oxygen-poor) blood away from tissues and merge to form larger systemic veins. - Ultimately the blood flows back to the right atrium. CIRCULATORY ROUTE - In post-natal (after birth) circulation, the heart pumps blood into two closed circuits with PULMONARY CIRCULATION each beat— - The right side of the heart is the pump for 1. Systemic Circulation PULMONARY CIRCULATION; it receives all of 2. Pulmonary Circulation the dark-red deoxygenated blood returning - The left side of the heart is the pump for from the systemic circulation. SYSTEMIC CIRCULATION; it receives bright - Blood ejected from the right ventricle flows red oxygenated (oxygen-rich) blood from the into the pulmonary trunk, which branches into lungs. pulmonary arteries that carry blood to the - The left ventricle ejects blood into the aorta. right and left lungs. - From the aorta, the blood divides into - In pulmonary capillaries, around pulmonary separate streams, entering progressively alveoli, blood unloads CO2, which is exhaled, smaller systemic arteries that carry it to all and picks up O2 from inhaled air. organs throughout the body—except for the - The freshly oxygenated blood then flows into pulmonary alveoli (air sacs) of the lungs, which pulmonary veins and returns to the left are supplied by the pulmonary circulation. atrium. - In systemic tissues, arteries give rise to smaller-diameter arterioles, which finally lead into extensive beds of systemic capillaries.  FETAL CIRCULATION LYMPHATIC SYSTEM AND IMMUNITY - exists only in the fetus and contains special IMMUNITY/resistance - is the ability to structures that allow the developing fetus to ward off damage or disease through our exchange materials with its mother via defenses. PLACENTA SUSCEPTIBILITY - vulnerability or lack - It differs from the postnatal (after birth) of resistance circulation because the lungs, kidneys, and The two general types of immunity: digestive canal organs do not begin to function until birth. 1. INNATE (nonspecific) IMMUNITY - The fetus obtains O2 and nutrients from the - refers to defenses that are present at birth. maternal blood and eliminates CO2 and other - does not involve specific recognition of a waste into it. microbe and acts against all microbes in the - As soon as a full-term fetus is delivered, there same way. is increased uptake of oxygen by the lungs - components of innate immunity are during the infant’s first and subsequent - the first line of defense (the physical and inhalations. chemical barriers of the skin and mucous - Once breathing begins, placental blood flow membranes) ceases. As a direct result of aeration of the - the second line of defense (antimicrobial lungs, the ductus arteriosus and ductus substances, natural killer cells, phagocytes, venosus undergo vasoconstriction and the inflammation, and fever). foramen ovale closes. Innate Immune Responses - represent immunity’s early warning system and are designed to prevent microbes from entering the body and to help eliminate those that do gain access. 2. ADAPTIVE (specific) IMMUNITY - refers to defenses that involve specific recognition of a microbe once it has breached the innate immunity defenses. - is based on a specific response to a specific microbe; that is, it adapts or adjusts to handle a specific microbe. - involves LYMPHOCYTES (a type of white blood cell) called T lymphocytes (T cells) and B lymphocytes (B cells).  LYMPHATIC SYSTEM This long duct, approximately 38–45 cm (15–18 in.), begins as a dilation called LYMPHOID/LYMPHATIC SYSTEM - the CISTERNA CHYLI anterior to the contributes to homeostasis by draining second lumbar vertebra. interstitial fluid as well as providing the mechanisms for defense against disease LYMPH PLASMA – fluid flowing in the lymph vessel LYMPHATIC VESSELS – vessel that transport the lymph plasma The major difference between interstitial fluid and lymph plasma is location: Interstitial fluid is found between cells, and lymph plasma is located within lymphatic vessels and lymphoid tissue. LYMPHOID TISSUE - is a specialized form of reticular connective tissue that contains large numbers of lymphocytes (agranular white blood cells) LYMPHATIC TRUNK AND DUCTS - The lymph plasma passage from the lymphatic trunks to the venous system differs on the right and left sides of the body. - On the RIGHT SIDE, the three lymphatic trunks usually open independently into the venous system on the anterior surface of the junction of the internal jugular and subclavian veins 1. RIGHT JUGULAR TRUNK 2. RIGHT SUBCLAVIAN TRUNK 3. RIGHT BRONCHOMEDIASTINAL TRUNK - Rarely, the three trunks will join to form a short RIGHT LYMPHATIC DUCT that forms a single junction with the venous system. - On the LEFT SIDE of the body, the largest lymph vessel, the THORACIC DUCT forms the main duct for return of lymph plasma to the blood.  THYMUS - bilobed organ located in the mediastinum between the sternum and the aorta. - It extends from the top of the sternum or the inferior cervical region to the level of the fourth costal cartilages, anterior to the top of the heart and its great vessels - high content of lymphoid tissue and a rich blood supply – reddish appearance With age, fatty infiltrations replace the lymphoid tissue – yellowish color SPLEEN Largest single mass of lymphatic tissue in the body Soft, oval, encapsulated organ of variable size (about 12 cm or 5 in.) located in the left hypochondriac region between the stomach and diaphragm WHITE PULP - carries out immune functions similar to lymph nodes (via phagocytosis) RED PULP - performs three functions related to blood cells: 1. removal by macrophages of ruptured, worn out, or defective LYMPH NODES blood cells and platelets 2. storage of platelets, up to one- Around 600 bean-shaped structures third of the body’s supply around lymphatic vessels scattered 3. production of blood cells throughout the body, 1–25 mm (0.04–1 (hemopoiesis) during fetal life in.) long Functions as a type of filter, trapping foreign substances and the filtered lymph then leaves the other end of the lymph node LYMPHOID NODULES - are egg-shaped masses of lymphoid tissue TONSILS - masses of lymphoid tissue covered with a mucous membrane. participate in immune responses against inhaled or ingested foreign substances  NOTES: Bright red – oxygenated blood Dark red – deoxygenated blood Left ventricle – thickest layer wall among all the chambers Pulmonary arteries – carry deoxygenated blood from the heart to the lungs for oxygenation Pulmonary veins – carry oxygenated blood from the lungs back to the heart Arteries (except for pulmonary arteries) – carry oxygenated blood away from the heart to the body Veins (except pulmonary veins) – carry deoxygenated blood back to the heart Aorta – largest blood vessel and largest artery Inferior vena cava – largest vein Largest capillary (sinusoids) – found at the liver Arterioles – site for greatest resistance Arteries – considered as stressed volume Capillaries – largest cross-sectional area Veins – capacitance vessels Phagocytosis – cell eating Pinocytosis – cell drinking Neutrophils – bacteria Lymphocytes – viral infections Monocytes – phagocytosis Eosinophils – allergies Basophils – parasites