Cooked 5 Cardiovascular System PDF

**5.1 Overview of the Cardiovascular system (COOKED 5)** **Cardiovascular system** - Made up of the heart and blood vessels. - The heart pumps blood through blood vessels - It brings nutrients to cells and helps get rid of waste - Exchange of substances occurs through interstitial fluid...

**5.1 Overview of the Cardiovascular system (COOKED 5)** **Cardiovascular system** - Made up of the heart and blood vessels. - The heart pumps blood through blood vessels - It brings nutrients to cells and helps get rid of waste - Exchange of substances occurs through interstitial fluid **Circulation allows for exchange of materials** - The system works with all other organ systems - Thousands of miles of blood vessels move the blood and its contents to and from all organs ***Gas exchange*** - Working with the respiratory system, blood drops off carbon dioxide and picks up oxygen in the lungs ***Nutrient exchange*** - From digestive system - Works with the liver at the kidneys **Functions of the Cardiovascular system** Transport: oxygen, co2, waste products, nutrients, hormones, and immune system cells. - Immune system cells and their associated antibodies and chemical signals help protect the body from infection Homeostasis: plays a central role in maintaining homeostasis for various internal conditions (temp, ph balance, water, electrolyte levels. ***Lymphatic system*** - Works with the immune system and assists the cardiovascular system by collecting excess interstitial fluid and returning it to the blood - When fluid enters the lymphatic vessels, it is called lymph. **5.2 The types of Blood Vessels** - **Arteries**: carries blood away from the heart. Walls have 3 layers -endothelium: the thin, inner epithelium -middle layer: smooth muscle and elastic tissue (arteries can expand and recoil from this) -outer layer: connective tissue ***Arterioles*** - Small arteries. Middle layer has mostly smooth muscle - It contracts to constrict the vessel, reducing blood flow and raising blood pressure - When relaxed, the vessel dilates, increasing blood flow and reducing blood pressure. - **Capillaries**: microscopic vessels between arterioles and venules. - Walls are only made of endothelium - Capillary beds form where gas, nutrients, and waste exchange occur - Precapillary sphincters, which control blood flow through the capillary bed. - When closed, blood instead flows through an arteriovenous shunt. ***Venules***- small veins that receive blood from the capillaries - **Veins:** carry blood toward the heart - Small middle layer - Contain valves - Thinner walls **5.3 The Heart is a Double Pump** **The Heart** - The heart points towards the left hip - It consists mostly of the myocardium, which is made of cardiac muscle tissue. - Intercalated disks (gap junctions, desmosomes) - Surrounded by a sac called the pericardium, which secretes pericardial fluid for lubrication - Internally, the septum divides the heart into right and left sides - Consists of 4 champers, 2 upper atria and two lower ventricles ***Two Types of Valves: Semilunar valves and atrioventricular valves (AV)*** - The AV values are reinforced by chordae tendineae. - Left AV valve- bicuspid, or mitral valve - Right AV valve- tricuspid valve - Semilunar valves: pulmonary valve and aortic valve **Coronary Circulation: The Heart's Blood Supply** - The myocardium needs its own blood supply Coronary arteries supply it. - They are the first branches off the aorta Coronary veins drain it - Empty into the right atrium Coronary artery disease- blockage in the coronary arteries causes a myocardial infarction (heart attack) **Passage of Blood through the Heart** Structure and Function Details - The walls of the left ventricle are thicker than the right ventricle because it must pump blood to the entire body, not just to the lungs. - The walls of atria are thinner than ventricles - Pulmonary capillaries within the lungs allow gas exchange - O2 enters the blood, co2 waste is excreted from the blood. **The Cardiac Cycle** - First the atria contract together, then the ventricles, then the heart relaxes. - Systole: heart contraction - Diastole: heart relaxation - Occurs 70 times per minute on average - First sound: closure of the AV valves - Second sound: closure of the semilunar valves - Murmur: a swishing sound between the sounds from regurgitation of blood (leaky valves) **Internal Control of the Heartbeat** Internal Conduction System - SA node (pacemaker)-\>AV Node (delay switch)-\> bundle of his/av bundle-\>Rt and left bundle branches-\> Purkinje fibers **External Control of the Heartbeat:** - The cardiac control center in the brain increases or decreases the heart rate depending on the body's needs - Some hormones increase heart rate **Electrocardiogram (ECG)** - Recording of the electrical changes in the heart during a cardiac cycle - The atria produce an electrical current, called the P wave, when stimulated by the SA node QRS complex- waves of electrical currents traveling through the ventricles - Signals that the ventricles are about to contract - The recovery of the ventricles is represented as the T wave ***Detects abnormnalities*** - Ventricular fibrillation- caused by uncoordinated, irregular electrical signals in the ventricles - The heart can't pump blood; tissues become starved of oxygen - Defibrillation- applying a strong electrical signal to reset the heart; hopefully, the SA node will start firing again. **5.4 Blood Pressure** Blood pressure: the pressure that blood exerts against a blood vessel wall. - Highest in the aorta, right next to the heart - It progressively decreases as blood moves through the body's vessels- arteries, arterioles, capillaries, venules, and finally the veins. - Lowest in the superior and inferior venae cave, which enter the right atrium **Pulse = heart rate** - Pulse- surge of blood into an artery causes the walls to stretch, and then recoil - Usually measured in the radial artery at the wrist or carotid artery in the neck - A measurement of the heart rate; averages 60-80 beats per minute **Blood Flow is Regulated** ***Blood pressure moves blood in arteries*** - Contraction of ventricles creates blood pressure, which propels blood through the arteries - Measured with a sphygmomanometer, in the brachial artery of the arm. - Systolic pressure- the highest pressure, when blood is ejected from the heart. - Diastolic pressure- the lowest pressure, when the ventricles relax - Average is 120/80 mmHg (systolic/diastolic) - Hypertension- high blood pressure - Hypotension- low blood pressure ***Blood Flow is Slow in the Capillaries*** - Blood pressure decreases as it flows away from the heart - It is slowest in the capillaries to increase the exchange of gases, nutrients, and waste - Adjusted by the precapillary sphincters. ***Blood Flow in Veins Returns Blood to Heart*** - Blood pressure is very low in the veins, so doesn't contribute much to the movement of blood - Venous return is dependent on three additional factors - Skeletal muscle pump (depends on skeletal muscle contraction) - Respiratory pump (depends on breathing) - Valves present in veins **5.5 Two Cardiovascular Pathways** - A pulmonary circuit circulates blood through the lungs. - Systemic circuit circulates blood through the body tissues. **Pulmonary Circuit: Exchange of Gases** - Right atrium (deoxygenated blood-\>right ventricles-\>pulmonary trunk-\>right and left pulmonary arteries-\>pulmonary arterioles-\>pulmonary capillaries (blood becomes oxygenated) -\>pulmonary veins-\>left atrium **Systemic Circuit: Exchanges with Interstitial Fluid** - Left Atrium (oxygenated blood) -\> left ventricle-\> aorta-\> arterioles-\>tissue capillaries (gas exchange occurs) -\> venules (deoxygenated blood) -\> veins-\> superior and inferior vena cava-\> right atrium Usually, blood flows from the aorta into an artery that supplies an organ, then through veins back to one of the vena cava Aorta-\>renal artery-\>kidney-\>renal vein-\>inferior vena cava However, there are special routes that don't follow this pathway (hepatic portal system) **Hepatic Portal System: Specialized for Blood Filtration** *Hepatic Portal Vein:* - Brings nutrient rich blood from the digestive tract to the liver - The liver synthesizes blood proteins from the amino acids in the hepatic portal vein and stores the glucose as glycogen - The liver also removes toxins and pathogens that enter the blood through the digestive system - Blood is drained from the liver into the hepatic veins, which drain into the inferior vena cava. **5.6 Exchange at the Capillaries** Two forces drive fluid in and out of capillaries - Blood pressure drives fluid out of the capillary, mainly at the arterial end of the capillary bed - This fluid contains everything that blood contains except cells and plasma proteins - Osmotic pressure draws water into the capillary by osmosis, mostly at the venule end. - Some tissue fluid enters lymphatic capillaries and becomes lymph, which is eventually returned to the cardiovascular system **5.7 Cardiovascular Disorders** Cardiovascular disease (CVD) - Leading cause of early death in western countries - Disorders of the blood vessels. - Hypertension (high blood pressure) and atherosclerosis often lead to a stroke, heart attack, or aneurysm **Disorders of blood vessels** - A systolic pressure of 140 or greater or a diastolic pressure of 90 or greater - A "silent killer" because there are a few symptoms until it causes kidney failure, a heart attack, or stroke - Treated with diuretics, which increases the production of urine, and other drugs. **Disorders of the BVs** ***Atherosclerosis*** - Buildup of atherosclerotic plaque in the walls of blood vessels. - Plaques narrow blood vessel diameter, decreasing blood supply to tissues - Can cause clots to form in the roughened walls of arteries - Thrombus- stationary clot - Embolus- clot that detaches and moves to distant sites. ***Stroke (cerebrovascular accident, or CVA*** - Occurs when a cranial artery is blocked or bursts - Part of the brain dies due to lack of oxygen - Symptoms may include numbness of hands or face, difficulty speaking, and inability to see in one eye ***Myocardial infarction (MI, or heart attack)*** - Part of the heart dies due to lack of oxygen - Caused by a blocked coronary artery - Begins with angina pectoris, pain in the chest from a *partially* blocked coronary artery - Can be treated with drugs that dilate blood vessels ***Aneurysm*** - A ballooning of a blood vessel, most often the abdominal aorta or blood vessels in the brain - Atherosclerosis and hypertension can weaken a vessel and cause ballooning - If a major artery ruptures, death can result ***Dissolving blood clots*** - Medical treatment for thromboembolism- tissue plasminogen activator (t-PA) - That is, a biotechnology drug - Converts plasminogen, a protein in blood, into plasmin, an enzyme that dissolves blood clots - Prevention of thromboembolism-aspirin - Lowers probability of clot formation and first heart attacks, among other health benefits, when taken at low doses ***Treating Clogged Arteries*** - Coronary bypass operation: a vein from the leg is taken and used to bypass a clogged artery - Gene therapy: injection of the gene for vascular endothelial growth factor induces the growth of new vessels (no need for bypass surgery) - Angioplasty: a tube is inserted into the clogged artery to insert a stent- a mesh cylinder to hold it open (stents are usually coated in drugs to dissolve the blockages ***Heart Failure*** **Treatments:** - Wrapping the heart to prevent enlargement - Implantable cardio-defibrillator corrects an irregular rhythm - Heart transplant - Injection of stem cells to repair damaged heart - Left ventricular assist device- battery powered pump to assist the heart - Total artificial heart- temporary solution