GCSF 2013 Human Structure & Function PDF

GCSF 2013 Human Structure & Function Topic: The Cardiovascular System  Blood Heart List of Blood vessels contents Cardio Lymphatic system Introduction A closed system of the heart and blood vessels. The heart pumps blood. Blood vesse...

GCSF 2013 Human Structure & Function Topic: The Cardiovascular System  Blood Heart List of Blood vessels contents Cardio Lymphatic system Introduction A closed system of the heart and blood vessels. The heart pumps blood. Blood vessels allow blood to circulate to all parts of the body. The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products. 4.1 Blood: Learning outcomes 1. Describe the components of whole blood, blood plasma and the structure of blood cells. 2. Explain the functions of blood, blood plasma and blood cells. 3. State blood groups. Blood Components Plasma (55%) Water (90%), ions, proteins, gases, nutrients, wastes, hormones. Cells (45%) RBCs, WBCs, platelets. Develop from stem cells in bone marrow. Blood Cell Formation Haematopoiesis: blood cell formation Occurs in red bone marrow Skull, pelvis, ribs, sternum, humerus, femur Erythrocytes Red blood cells (RBCs). Transport O2, in blood. Biconcave discs. Anucleate (no nucleus). Hemoglobin: iron-containing protein, binds to O2. Life span: 100-120 days. Common Health-related Problem with RBC Anemia: decrease in oxygen- carrying ability of blood Low RBC count or deficient hemoglobin content Sickle-cell Disease: abnormal hemoglobin Genetic disorder Leukocytes White blood cells (WBCs). Defend body against infection and tumors. Locate areas of tissue damage by responding to chemicals. Types: neutrophils, eosinophils, basophils, lymphocytes, monocytes. Common Health-related Problem with WBC Leukaemia: bone marrow becomes cancerous huge numbers of WBCs Treatment: chemotherapy, radiotherapy, stem cell transplant. Platelets Cell fragments (irregularly-shaped bodies) Needed for clotting blood.  The Functions of Blood O2 & Nutri Deliver O2, nutrients to all body cells. Waste Transport waste products from cells for elimination. Hormones Transport hormones. Temp Maintain body temperature (distribute heat). pH Maintain pH (carry buffers). Blood volume Maintain flued volume. Clotting Prevent blood loss (clotting). Antibodies Prevent infection (WBCs, antibodies)  Vascular spasm – constrict damaged blood vessels Platelet plug forms Hemostasis: Platelets stick and bind to damaged site Stoppage of Release chemicals to attract more platelets Bleeding Coagulation Blood clotting Fibrin threads forms mesh that traps RBCs Time: blood clot normally forms within 3-6 mins. Clotting 1 2 Factors 3 4 5 6 7 8 9 10 11 12 13 Blood Clotting Disorders Embolus- thrombus Hemophilia- hereditary Thrombus- clot in breaks away from vessel bleeding disorder, lack unbroken blood vessel wall and floats freely clotting factors Coronary thrombosis = Cerebral embolus = Haemophilia A and B – heart attack stroke Haemophilia A means low levels of factor (8) and Haemophilia B is low levels of factor (9)  Antigen- foreign substance that immune system recognizes Antibodies- Y-shaped proteins secreted by WBC’s that attach to antigens Human Blood Groups Agglutination- clumping caused by antibodies binding to antigens on RBCs A antigen RBC surface proteins: B antigen Rh antigen ABO Blood Grouping Blood Grouping ABO Rh(+/-) Blood Grouping Hemolytic Newborn Disease 4.2 Structure & Organization of The Heart 1. Describe the location, structure of the heart wall, the chambers, heart valves and major blood vessels that enters and exit the heart. 2. Explain the functions of the heart valves. 3. Explain the mechanism of blood flow through the heart and blood supply of the heart. The Heart Location Thorax between the lungs. At the mediastinum. Pointed apex directed toward the left, 5th intercostal muscle. About the size of your fist. The Heart Figure The Heart: Coverings Pericardium – a double serous membrane Visceral pericardium, next to heart. Parietal pericardium, outside layer. Build up of connective tissue. Serous fluid fills the space between the layers of pericardium. To protect the heart, mesothelial cells secrete lubricating fluids to reduce friction with surrounding environment. External Heart Anatomy The Heart: Chambers Right and left side act as separate pumps Four chambers Atria- Receiving chambers 1. Right atrium 2. Left atrium Ventricles- Discharging chambers 1. Right ventricle 2. Left ventricle The Heart: Valves Allow blood to flow in only one direction Four valves Atrioventricular valves – between atria and ventricles 1. Bicuspid valve (left) 2. Tricuspid valve (right) Semilunar valves between ventricle and artery 1. Pulmonary semilunar valve 2. Aortic semilunar valve Operation of Heart Valves Valves are flapping (leaflets) that act as one-way inlets for blood coming into a ventricle and one-way outlets for blood leaving a ventricle. The papillary muscles pull on the chordae tendineae and help to open the cusps when the ventricles are relaxing and filling with blood. The chordae tendineae prevent the cusps of the AV valves from being shoved up into the atria when the ventricles contract. If this were to happen, blood would regurgitate back into the atria. The Heart: Associated Great Vessels Aorta - Leaves left ventricle Pulmonary arteries - Leave right ventricle Vena cava - Enters right atrium Pulmonary veins (four) - Enter left atrium Coronary Circulation Blood in the heart chambers does not nourish the myocardium The heart has its own nourishing circulatory system Coronary arteries Cardiac veins Blood empties into the right atrium via the coronary sinus 4.3 Cardiac Cycle 1 2 3 State the Explain the phases Explain the components and of cardiac cycle and regulation of heart pathway of the cardiac output. rate and stroke conducting system. volume.  The Heart: Conduction System Intrinsic conduction system (nodal system). Heart muscle cells contract, without nerve impulses, in a regular, continuous way. Special tissue sets the pace or rhythm Sinoatrial node (SA)- Pacemaker Atrioventricular (AV) node Atrioventricular bundle- Bundle branches – Bundle of HIS Purkinje fibers  Heart Conduction & Contraction Contraction is initiated by the SA node. Sequential stimulation occurs at other autorhythmic cells. The SA node starts the sequence by causing the atrial muscles to contract. Next, the signal travels to the AV node. Through the bundle of HIS, down the bundle branches, and through the Purkinje fibers, causing the ventricles to contract. Cardiac Cycle The cardiac cycle is the performance of the human heart (heartbeat → heartbeat) It consists of two periods: Diastole – the heart muscle relaxes and refills with blood. Systole – the contraction and pumping of blood. 5 Phases of the Cardiac Cycle 1. Atrial Systole 2. Early Ventricular Systole 3. Ventricular Systole 4. Early Ventricular Diastole 5. Late Ventricular Diastole Cardiac Output Amount of blood your heart pumps in 1 minute. Normal output - It’s different from one to another, depending on their body size. Usually, an adult heart pumps about 5 liters of blood/minute at rest. But when you run or exercise, it increases 3-4 times more than the normal output. To make sure your body gets enough oxygen and required nutrients, especially glucose. Therefore, the cardiac output is the heartbeats (rate) per minute multiplied by the amount of blood pumped with each beat. Measurement tools: Pulmonary artery catheter; Echocardiogram; Arterial pulse waveform analysis. Stroke Volume (SV) Stroke Volume (SV) is the volume of blood in millilitres ejected from each ventricle due to the contraction of the heart muscle which compresses these ventricles. SV is the difference between end diastolic volume (EDV) and end systolic volume (ESV). Stroke volume is the amount of blood each ventricle pumps out in one cardiac cycle. Stroke volume is approximately 70 ml. Regulation of Heat Rate & Stroke Volume HR - During exercise, your heart typically beats faster so that more blood gets out to your body. SV - Heart can also increase its stroke volume by pumping more forcefully. SV - Increasing the amount of blood that fills the left ventricle before it pumps. 4.4 Structure of Blood Vessel, Function and Circulatory Routes 1 2 3 4 Describe the Explain the Describe the Explain the structure of the functions of various regulation of blood vessels. blood vessels. circulatory blood pressure. routes. Blood Vessel Structure & Function Tunica Intima Arteries and veins are comprised of the inner layer three distinct layers while the much it is the thinnest layer smaller capillaries are composed of a single continuous layer of endothelial cells a single layer. supported by connective tissue and supportive cells Tunica Media surrounding the tunica intima comprised of smooth muscle cells and elastic and connective tissues arranged circularly around the vessel Tunica Externa the outermost layer also called tunica adventitia composed entirely of connective fibers and surrounded by an external elastic lamina to anchor vessels with surrounding tissues. Differences Between Blood Vessels  Double-closed Blood Circulation 1. Pulmonary 2. Systemic Systemic Circulatory System Systemic Circulatory System Regulation of Blood Pressure Blood pressure is measured using an automated blood pressure monitor, or manually using a stethoscope and sphygmomanometer. It is given as two values (e.g. 120/80 mmHg), measured in “millimeters of mercury (mmHg)”: Systolic pressure – the first number (120 mmHg in the example) is the pressure of the blood during the heart contraction (systole). Diastolic pressure – the second number (80 mmHg in the example) is the pressure of the blood when the heart is at rest between heart beats (diastole). Short-Term BP Regulation Short-term regulation of blood pressure is controlled by the autonomic nervous system (ANS). Changes in blood pressure are detected by baroreceptors. These are in the arch of the aorta and the carotid sinus. Increased arterial pressure stretches the wall of the blood vessel, triggering the baroreceptors. These baroreceptors then feedback to the ANS. The ANS then acts to reduce the heart rate via the efferent parasympathetic fibers (vagus nerve). This reduces the blood pressure. Short-Term BP Regulation Decreased arterial pressure is detected by baroreceptors, which trigger a sympathetic response. This stimulates an increase in heart rate and cardiac contractility leading to increased blood pressure. Baroreceptors cannot regulate blood pressure long-term. This is because the mechanism that triggers baroreceptors resets itself once a more adequate blood pressure is restored. Diagram: Baroreceptors (Arch of Aorta and Carotid Sinus) Long-Term BP Regulation There are several physiological mechanisms that regulate blood pressure in the long-term, the first of which is the renin-angiotensin- aldosterone system (RAAS). Renin-Angiotensin-Aldosterone System (RAAS) (Increasing BP) Renin is a peptide hormone released by the granular cells of the juxtaglomerular apparatus in the kidney. It is released in response to: 1. Sympathetic stimulation. 2. Reduced sodium-chloride delivery to the distal convoluted tubule. 3. Decreased blood flow to the kidney. 4. Renin facilitates the conversion of angiotensinogen to angiotensin I. This is then converted to angiotensin II using angiotensin-converting enzyme (ACE). Long-Term BP Regulation Angiotensin II is a potent vasoconstrictor. It acts directly on the kidney to increase sodium reabsorption in the proximal convoluted tubule. Sodium is reabsorbed via the sodium-hydrogen exchanger. Angiotensin II also promotes the release of aldosterone. Aldosterone promotes salt and water retention by acting at the distal convoluted tubule to increase expression of epithelial sodium channels. Long-Term BP Regulation Furthermore, aldosterone increases the activity of the basolateral sodium-potassium ATP-ase. This, consequently, increases the electrochemical gradient for movement of sodium ions. More sodium collects in the kidney tissue and water then follows by osmosis. This results in decreased water excretion and therefore increased blood volume and blood pressure. ACE also breaks down a substance called bradykinin which is a potent vasodilator. Therefore, the breakdown of bradykinin increases the constricting effect. This potentiates the overall increase in blood pressure. Long-Term BP Regulation Anti-Diuretic Hormone (ADH) (Increasing BP) The second mechanism by which blood pressure is regulated is via the Anti-Diuretic Hormone (ADH). It is produced in the hypothalamus and stored and released from the posterior pituitary gland. This is usually in response to thirst or an increased plasma osmolarity. ADH acts to increase the permeability of the collecting duct to water by inserting aquaporin channels (AQP2) into the apical membrane. It also stimulates sodium reabsorption from the thick ascending limb of the loop of Henle. This increases water reabsorption thus increasing plasma volume and decreasing osmolarity. Long-Term BP Regulation Further Control of Blood Pressure (Reducing BP) Other factors that can affect long-term regulation of blood pressure are natriuretic peptides. These include: Atrial natriuretic peptide (ANP) is synthesized and stored in cardiac myocytes. It is released when the atria are stretched and indicates high blood pressure. ANP acts to promote sodium excretion. It dilates the afferent arteriole of the glomerulus, increasing the glomerular filtration rate (GFR). Moreover, ANP inhibits sodium reabsorption along the nephron. Conversely, ANP secretion is low when blood pressure is low. Prostaglandins act as local vasodilators to increase GFR and reduce sodium reabsorption. Moreover, they act to prevent excessive vasoconstriction triggered by the RAAS and sympathetic nervous system. Diagram: Glomerulus (Afferent & Efferent Arterioles) 4.5 Lymphatic System 01 02 03 State the Explain the Describe the lymph components of functions of the circulation. lymphatic system. lymphatic system. Components of Lymphatic System The lymphatic system primarily consists of lymphatic vessels, which are similar to the veins and capillaries of the circulatory system. The vessels are connected to lymph nodes, where the lymph is filtered. The tonsils, adenoids, spleen and thymus are all part of the lymphatic system. There are hundreds of lymph nodes in the human body. They are located deep inside the body, such as around the lungs and heart, or closer to the surface, such as under the arm or groin. The lymph nodes are found from the head to around the knee area. Diagram: Lymphatic vessels, lymph nodes, Diagram: Location of lymph nodes Diagram: Lymphatic organs Functions of Lymphatic System The primary function of the lymphatic system is to make sure leaked blood returns back to the bloodstream. Like lymph nodes, the spleen acts as a blood filter; it controls the amount of red blood cells in the body. It also part of our immune system, produce lymphocytes (antibodies) to fight against infection. Thymus stores immature lymphocytes (specialized white blood cells) and prepares them to become active T cells, which help destroy infected or cancerous cells. Tonsils are the body's "first line of defense. They take sample of bacteria and viruses that enter the body through the mouth or nose. The secondary function of the lymphatic system, the lacteals is to absorb fats and fat-soluble vitamins through the digestive system and the subsequent transport of these substances back to the venous circulation. Diagram: Villi (Small intestine) Lacteal Lymphatic Circulation When a small amount of fluid leaks out from the blood vessels, it collects in the spaces between cells and tissues (interstitial space). Some of the fluid returns to the cardiovascular system, and the rest is collected by the lymph vessels of the lymphatic system. The fluid that collects in the lymph vessels is called lymph. The lymphatic system then returns the lymph to the cardiovascular system. Unlike the cardiovascular system, the lymphatic system is not closed circulatory system and has no central pump (or heart). Lymph moves slowly in lymph vessels. It is moved along in the lymph vessels by the squeezing action of smooth muscles and skeletal muscles. Diagram: Lymphatic circulation Thank you