Cardiovascular System PDF

Acupuncture Biomedical Foundation Acupuncture 1160 W3-1,2 The Cardiovascular System Di Wu, R.TCM.P. Relationship between two circulations Blood vessels The Cardiovascular System Arteries and arterioles Arterial walls are thicker than venous wall...

Acupuncture Biomedical Foundation Acupuncture 1160 W3-1,2 The Cardiovascular System Di Wu, R.TCM.P. Relationship between two circulations Blood vessels The Cardiovascular System Arteries and arterioles Arterial walls are thicker than venous walls Largest arteries: their tunica media has lots of elastic tissue and little smooth muscle Arterioles: the tunica media is mostly smooth muscle Systemic blood pressure is mainly determined by the resistance these small muscular arteries provide to blood flow Anastomotic arteries: collateral circulation provides a backup route for blood flow if one artery gets blocked. End-Arteries: if an end-artery gets blocked, the tissue it supplies dies because there is no other blood supply. The Cardiovascular System Capillaries Capillaries are permeable to water the other small molecules, but blood cells and large molecules are too large to pass through Capillaries are about 3-4 μm in diameter Blood-brain barrier: some capillaries are less porous to protect delicate neural tissue. Capillary Refill Time: a prolonged capillary refill time suggests poor perfusion or dehydration The Cardiovascular System Veins and venules Vein walls are thinner than artery walls Some large veins: have valves to prevent blood from flowing backward Veins hold a large portion of the body’s blood (2/3) Venous bleeding is easier to stop The Cardiovascular System Capillary exchange Exchange of other substances Exchange of gases The Cardiovascular System Heart-Position The heart is positioned obliquely in the chest cavity within the mediastinum and tilts slightly to the left. The bottom tip of the heart, known as the apex, is about 9 cm to the left of the midline at the level of the 5th intercostal space and points downward and to the left. The flat upper surface of the heart is called the base The Cardiovascular System Heart-Structure Pericardium: Fibrous pericardium Serous pericardium parietal pericardium visceral pericardium Myocardium: rich in mitochondria, intercalated discs Endocardium: thin membrane made up a single layer of flattened epithelial cells, minimize friction as blood flow over it. The Cardiovascular System Heart-Interior of the Heart Interior of the Heart The Cardiovascular System Heart-Blood Flow Blood Flow Through the Heart The Cardiovascular System Heart-The Conducting System Nerve supply to the heart: Cardiovascular centre: medulla oblongata Vagus nerve (parasympathetic): slow down heart rate T1-5 thoracic segments (sympathetic) : increase heart rate The Cardiovascular System Heart-The Cardiac Cycle cardiac cycle animation - YouTube At rest, the healthy adult heart is likely to beat at a rate of 60–90 beats per minute (bpm). During each heartbeat or cardiac cycle, the heart contracts (systole) and then relaxes (diastole). At a typical heart rate of 74 bpm, each cycle lasts about 0.8 seconds and has three stages The Cardiovascular System Heart-Electrocardiogram The Cardiovascular System Heart-Cardiac Output Cardia output = Stroke volume x Heart rate 5L (70mL x 72bmp) at rest 25L or 35 L during exercise (cardiac reserve: 20-30L) Factors affecting stroke volume Factors affecting heart rate Ventricular end-diastolic volume (VEDV – Autonomic Nervous System preload) Circulating Chemicals Venous return: Exercise and Fitness Level Position of the body Position Skeletal muscle pump Gender Respiratory pump Age Strength of myocardial contraction Temperature Blood volume The Cardiovascular System Blood pressure (BP) BP = 120/80 mmHg systolic pressure/diastolic pressure Factors determining blood pressure Blood pressure = Cardiac output x Peripheral resistance The Cardiovascular System Pulse The pulse provides valuable information Heart rate Regularity: Strength Artery wall tension Factors affecting the pulse Peripheral artery narrowing or blockage Certain heart conditions Pulse diagnose Pulse checking The Cardiovascular System Circulation of the blood Venae Cavae and its main branches Aorta and its main branches The Cardiovascular System Circulation in the head and neck Circle of Willis Arterial Supply The Cardiovascular System Circulation in the head and neck Venous Return The Cardiovascular System Circulation in the upper limb The main veins of the right arm The main arteries of the right arm The Cardiovascular System Circulation in the thorax The Cardiovascular System Circulation in the abdomen The Cardiovascular System Portal circulation The Cardiovascular System Circulation in the pelvis and lower limb Aorta and its main branches The Cardiovascular System Shock The metabolic needs of cells are not met because of inadequate blood flow A drop in: - blood volume - blood pressure - cardiac output Types of shock： Hypovolemic shock: lose a significant amount of blood or fluids Cardiogenic shock: the heart is too damaged to pump enough blood Septic shock: the immune system overreacts to an overwhelming infection Neurogenic shock: spinal cord injury which leads to sever low blood pressure Anaphylactic shock: severe allergic reaction causes rapid blood vessel dilation Physiological changes during shock Compensated shock Uncompensated shock The Cardiovascular System Thrombosis and embolism Thrombosis: a thrombus blocks the blood flow to the tissues - slow blood flow - damage to blood vessels - increased blood clotting A. Partial blockage Embolism：an embolus travels through the with reduced bloodstream and blocks a blood vessel perfusion. - Arterial emboli: stroke, heart attack, B and C complete gangrene in limbs blockage causes - Venous emboli: pulmonary embolism distal tissue ischemia and Infarction: the death of tissue due to a infarction lack of blood supply Ischemia: the tissue function is impaired due to a lack of oxygen and the buildup of waste products The Cardiovascular System Oedema Excess tissue fluid accumulates cause swelling Sites of oedema: - superficial oedema: indentation after pressing the skin - dependent oedema: swelling happens in areas affected by gravity. - pulmonary oedema: fluid builds up in the lungs Causes of oedema： - Increased venous pressure: - Low plasma protein levels: - Impaired lymphatic drainage: - Increased capillary permeability Effusions: abnormal accumulation of fluid in body spaces - Pleural effusion: fluid builds up in the pleural cavity around the lungs - Ascites: effusion in the peritoneal cavity. The Cardiovascular System Diseases of the heart - Heart failure It happens when the heart can’t pump enough blood to meet the body's needs. Compensatory mechanisms in heart failure of oedema: - cardiac muscle mass increases - heart chambers enlarge - decreased renal blood flow activates the RAAS Right-sided heart failure: swelling in the limbs and organs Left-sided heart failure : fluid buildup in the lungs The Cardiovascular System Diseases of the heart - Ischemic heart disease Angina pectoris - heart needs more oxygen - it occurs when heart’s workload increase, Rest may relieve symptoms - chest pain, may spread to the arms, neck or jaw Myocardial infarction (heart attack) - a branch of a coronary artery is blocked - it occurs when heart’s workload increase - severe chest pain, rest may not relieve Complications of Myocardial Infarction - ventricular fibrillation - cardiogenic shock - rupture of a heart wall - pulmonary or cerebral embolism - pericarditis The Cardiovascular System Diseases of the heart - Cardiac arrhythmias Sinus bradycardia heart beat drops below 60 bpm with normal rhythm Sinus tachycardia heart beat exceeds 100 bpm with normal rhythm Asystole no electrical activity in heart’s ventricles resulting in no cardiac output Fibrillation Atrial fibrillation (AF) Ventricular fibrillation: medical emergency The Cardiovascular System Disorders of blood pressure - Hypertension Essential hypertension most common (95%), unknown causes Malignant hypertension diastolic pressure > 120 mmHg Secondary hypertension 5%, caused by other underlying diseases Complications of hypertention - heart: hypertrophy - brain: stroke - kidneys: kidney dysfunction or kidney failure - blood vessels: atheroma -> aneurysms, retinal damage The Cardiovascular System Case study Chandler flew back from holiday two days ago. His flight home was a long one – twelve hours – and he is still recovering from jet lag. However, he has noticed a nagging, throbbing pain in his right calf, and the area is swollen, red and tender to touch. His colleague at work suggests this could be a blood clot, specifically a deep venous thrombosis, probably secondary to having sat still in a cramped aeroplane seat over an extended period of time. 1. In which of the following blood vessels is it most likely that Chandler’s clot has formed? a. Femoral vein b. Radial vein c. Tibial vein d. Iliac vein 2. Why has obstruction of blood flow in Chandler’s leg caused swelling? a. Increased blood hydrostatic pressure b. Increased blood osmotic pressure c. Increased lymphatic osmotic pressure d. Increased interstitial fluid hydrostatic pressure The Cardiovascular System Case study 3. Chandler puts off going to the doctor because he is catching up with work following his holiday. Two days after the conversation with his colleague, he is woken in the morning with pain in his chest and difficulty breathing. What is the likeliest cause? a. Myocardial infarction b. Bacterial pneumonia c. Acute bronchitis d. Pulmonary embolism 4. The pain in Chandler’s chest is caused by accumulation of tissue wastes and inadequate blood supply. The correct term for inadequate blood supply to a tissue is: a. Necrosis b. Ischemia c. Infarction d. Embolism The Cardiovascular System Review and revise 10. Starting at the right atrium in List A, place the items in List B in the correct order to describe the circulation of the blood: List A List B Right atrium A. Pulmonary vein 1 ________ B. Left ventricle 2 ________ C. Pulmonary capillaries 3 ________ 4 ________ D. Left atrioventricular valve 5 ________ E. Systemic capillaries 6 ________ F. Right ventricle 7 ________ G. Aorta 8 ________ H. Pulmonary artery 9 ________ 10 ________ I. Systemic veins 11 ________ J. Right atrioventricular valve 12 ________ K. Aortic valve 13 ________ L. Left atrium Right atrium M. Systemic arteries The Cardiovascular System