2. SPR150S - Lecture 2.pptx

SPORT & PHYSICAL RECREATION STUDIES (SPR150S) DR SACHA WEST PRESENTED BY: DR JARON RAS LECTURE 2: THE CARDIOVASCULAR SYSTEM – THE HEART  LECTURE OBJECTIVES - Discuss the functions of the cardiovascular system - Demonstrate knowledge of the anatomy of the heart (...

SPORT & PHYSICAL RECREATION STUDIES (SPR150S) DR SACHA WEST PRESENTED BY: DR JARON RAS LECTURE 2: THE CARDIOVASCULAR SYSTEM – THE HEART  LECTURE OBJECTIVES - Discuss the functions of the cardiovascular system - Demonstrate knowledge of the anatomy of the heart (know how to label the heart) - Discuss the difference between the pulmonary and systemic circulation - Describe the circulation of oxygenated and deoxygenated blood through the heart - Compare the different valves in the heart and their function - Identify the function of the conduction system of the heart and its  WHAT IS THE CARDIOVASCULAR SYSTEM? - It is an organ system that consists of specific structures that circulates blood to (OXYGEN + NUTRIENTS + HORMONES) and from (METABOLIC WASTE) cells and tissues - Function of the CV System: the body’s delivery system - These 3 components – blood, heart and vessels – make up the Cardiovascular System (which we will cover in the next few lectures) - All CV functions are dependent on the heart - This lecture focuses on the primary organ of the CV System: the HEART  ANATOMY OF THE CARDIO VASCULAR SYSTEM - The CV System is represented by the: 1)Heart 2)Blood 3)Arteries, Veins and Capillaries  FUNCTIONS OF THE CV SYSTEM 1) To transport nutrients, oxygen & hormones to the organs, muscles & cells throughout the body 2) To remove metabolic waste products (carbon dioxide & nitrogenous waste) from the body 3) To protect the body from infection & blood loss 4) To help the body maintain a constant body temperature (‘thermoregulation’)  THE HEART - Heart is a muscular organ - It is a pump that provides enough pressure to enable the blood to flow through the CV system - Approximately the size of a clenched fist: weighs only 400g = very powerful muscle - Beats approximately 100,000 times per day - At rest, heart pumps 5 litres of blood per  THE HEART - Consists of four chambers: the left side & right side each have one atrium & one ventricle - The right & left atrium (upper chambers): act as a receiving chamber & contract to push blood to the lower chambers - The right & left ventricle (lower chambers): serve as the primary pumping chambers of the heart, ANATOMY OF THE HEART * ( K N O W H O W T O L A B E L T H E H E A RT ) *  CIRCULATION - Pulmonary THROUGH THE HEART Circuit: takes - Two distinct but linked circuits place between the called the pulmonary & systemic heart & the lungs circuits - Pulmonary Circuit: transports blood to & from the lungs (picks up oxygen & delivers carbon dioxide for exhalation {breathing out}) - Systemic Circuit: - Systemic Circuit: transports takes place between the heart oxygenated blood to all the tissues & the body of the body & returns relatively CIRCULATION THROUGH THE HEART  LEFT SIDE OF THE HEART - Pulmonary veins: receives highly oxygenated blood from the lungs - The pulmonary veins pass this blood into the left atrium: pumps the blood into the left ventricle - Left ventricle: pumps oxygenated blood into the aorta - Aorta: pumps oxygenated blood on to the many branches of the systemic circuit - Oxygen & nutrients exit the systemic capillaries to RIGHT SIDE OF THE HEART - Blood exiting the systemic capillaries are low in oxygen concentration than when it entered (becomes deoxygenated blood) - The capillaries will ultimately unite to form venules, joining to form even larger veins - Deoxygenated blood eventually flows into two major systemic veins called: superior vena cava & inferior vena cava - The blood in the superior & inferior vena cava flows into the right atrium, which pumps blood into the right ventricle - Deoxygenated blood is then pumped by the pulmonary artery to the lungs for gas exchange, through the pulmonary circuit, SUMMARY OF THE HEART & THE CIRCULATION  INTERNAL STRUCTURE OF THE HEART - Septum: Wall or partition that divides the heart into chambers - Valve: Specialised structure that ensures one-way blood flow - Atrioventricular Valves: The valves between the atria & ventricles - Semilunar Valves: Valves at the openings of the pulmonary trunk & the  INTERNAL STRUCTURE OF THE HEART 1) Atrioventricular Valves: - Tricuspid Valve: Opening between the right atria & ventricle - Bicuspid (Mitral) Valve: Opening between the left atria & ventricle 2) Semilunar Valves: - Pulmonary Valve: Located at the base of the pulmonary trunk in the right ventricle - Aortic Valve: Located at the SUMMARY OF THE HEART VALVES  CONDUCTION SYSTEM OF THE HEART - Cardiac Muscle (Myocardium): Only found in the heart, possesses contractile units known as sarcomeres, exhibits rhythmic contractions & is not under voluntary control - The cardiac conduction system is a group of specialised cardiac cells in the walls of the heart that sends signals of the heart muscle causing it to contract (electrical signals) - Main components of the conduction system are: SA node, AV node, bundle of His, bundle branches, and Purkinje fibers - SA node starts the sequence by causing the atrial muscles to contract  CONDUCTION SYSTEM OF THE HEART - Rhythmic contraction is regulated by the Sinoatrial Node: Internal pacemaker of the heart, found in the superior wall of the right atrium, keeps heart rate steady at 70-80bpm - Conducting system provides the heart with its automatic rhythmic beat - The signal creates an electrical current that can be seen on a graph called an  ABNORMAL HEARTBEAT - Arrhythmias are abnormal rhythms of your heartbeat: heart may beat too fast, too slowly or in an irregular pattern - Can occur when the electrical impulses coming from the heart don’t fire as they normally should - Tachycardia: faster than normal heart rate at rest - Bradycardia: td slower than  TACHYCARDIA - Faster than normal heart rate at rest: above 100 beats per minute at rest - Stimulation of the sympathetic (cardio accelerator) nerves, releases hormones (epinephrine & norepinephrine) causes the heart to beat faster - Exercise increases the influence of the sympathetic nervous system which causes tachycardia - This therefore increases cardiac output (amount of blood  BRADYCARDIA - Slower than normal heart rate at rest: below 60 beats per minute at rest - Parasympathetic nervous system releases the hormone acetylcholine, it retards/slows down the rate of the heart - Bradycardia occurs frequently in endurance athletes because heart muscle is “strong” so requires less blood to be pumped to meet higher blood/oxygen demands to the muscles  CARDIAC OUTPUT: STROKE VOLUME & HEART RATE - Cardiac Output: the volume (amount) of blood pumped by the heart in 1 minute - Stroke Volume: the volume (amount) of blood ejected by the ventricles during a single heart beat - Heart Rate (HR): the number of heart beats per minute - Cardiac output is determined by: Heart rate x amount of blood ejected with each stroke (stroke volume) CO = SV x HR Cardiac Output (ml/min) = Stroke Volume (ml/beat) x Heart  FACTORS THAT AFFECT CARDIAC OUTPUT CO = SV x HR Cardiac Output (ml/min) = Stroke Volume (ml/beat) x Heart  CARDIAC OUTPUT: SV X HR - At rest: Cardiac output is approximately 5 litres per minute - During exercise: Can increase up to 30 litres per minute as both heart rate & stroke volume - Why does it increase with exercise? - Your body may need 3 to 4 times your normal CO because your muscles need more oxygen when you exert yourself - Your heart typically beats faster so that  EXERCISE TRAINING & CARDIAC OUTPUT - Prolonged aerobic exercise training (cardiovascular exercise) can also increase stroke volume, which can result in a lower (resting) heart rate - Trained individuals have a stronger & thicker heart muscle which results in improved filling of the heart (slower heart rate allows for more filling time) & improved ANY QUESTIONS?