The Circulatory System: A Closed Network of Blood Vessels and the Heart

The Circulatory System: A Closed Network of Blood Vessels and the Heart

The circulatory system is an essential part of the human body that ensures that all the organs and tissues receive the oxygen and nutrients they need to function

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Slide1The Circulatory SystemThe Heart, Blood Vessels, Blood Types

Slide2The Closed Circulatory System• Humans have a  closed circulatory system , typical of all vertebrates, in which blood is confined to vessels and is distinct from the interstitial fluid. – The heart pumps blood into large vessels that branch into smaller ones leading into the organs. – Materials are exchanged by diffusion between the blood and the interstitial fluid bathing the cells.

Slide3The Cardiovascular System• Three Major Elements – Heart, Blood Vessels, & Blood – 1.   The Heart - cardiac muscle tissue – highly interconnected cells – four chambers • Right atrium • Right ventricle • Left atrium • Left ventricle

Slide5Pathway of the blood• Superior Vena Cava • Right Atrium • Tricuspid Valve • Right Ventricle • Pulmonary Semilunar Valve • Lungs • Pulmonary Vein • Bicuspid Valve • Left Ventricle • Aortic Semilunar Valve • Aorta • To the bodies organs & cells

Slide6Circuits• Pulmonary circuit – The blood pathway between the right side of the heart, to the lungs, and back to the left side of the heart. • Systemic circuit – The pathway between the left and right sides of the heart.

Slide7The Cardiovascular System2.  Blood Vessels -A network of tubes – Arteries  arterioles  move away from the heart • Elastic Fibers • Circular Smooth Muscle – Capillaries  – where gas exchange takes place. • One cell thick • Serves the Respiratory System – Veins  Venules  moves towards the heart • Skeletal Muscles contract to force blood back from legs • One way values • When they break - varicose veins form

Slide9The Cardiovascular System3. The Blood A. Plasma Liquid portion of the blood. Contains clotting factors, hormones, antibodies, dissolved gases, nutrients and waste

Slide10The Cardiovascular System• The Blood B. Erythrocytes - Red Blood Cells – Carry hemoglobin and oxygen.  Do not have a nucleus and live only about 120 days. – Can not repair themselves.

Slide11The Cardiovascular System• The Blood C. Leukocytes – White Blood cells – Fight infection and are formed in the bone marrow – Five types – neutrophils, lymphocytes, eosinophils, basophils, and monocytes.

Slide12The Cardiovascular SystemThe Blood • D. Thrombocytes – Platelets. – These are cell fragment that are formed in the bone marrow from magakaryocytes . – Clot Blood by sticking together – via protein fibers called  fibrin.

Slide13Disorders of the Circulatory System• Anemia  -  lack of iron in the blood, low RBC count • Leukemia  -  white blood cells proliferate wildly, causing anemia • Hemophilia  -  bleeder’s disease, due to lack of fibrinogen in thrombocytes • Heart Murmur  -  abnormal heart beat, caused by valve problems • Heart attack  -  blood vessels around the heart become blocked with plaque, also called  myocardial infarction

Slide14Unit 9 – The HeartCardiovascular System The  Heart The  Heart

Slide15Functions of the Heart• Generating  blood  pressure • Routing  blood – Heart separates pulmonary and systemic circulations • Ensuring one-way  blood  flow – Heart valves ensure one-way flow • Regulating  blood  supply – Changes in contraction rate and force match blood delivery to changing metabolic needs

Slide16Size, Shape, Locationof the Heart • Size of a closed fist • Shape – Apex : Blunt rounded point of cone – Base : Flat part at opposite of end of cone • Located in thoracic cavity in mediastinum

Slide17Heart Cross Section


Slide19Heart Wall• Three layers of tissue – Epicardium : This serous membrane of smooth outer surface of heart – Myocardium : Middle layer composed of cardiac muscle cell and responsibility for heart contracting – Endocardium : Smooth inner surface of heart chambers

Slide20Heart Wall

Slide21External Anatomy• Four chambers – 2 atria – 2 ventricles • Auricles • Major veins – Superior vena cava – Pulmonary veins • Major arteries – Aorta – Pulmonary trunk

Slide22External Anatomy

Slide23Coronary Circulation

Slide24Heart Valves• Atrioventricular – Tricuspid – Bicuspid or mitral • Semilunar – Aortic – Pulmonary • Prevent blood from flowing back

Slide25Heart Valves

Slide26Function of the Heart Valves

Slide27Blood Flow Through Heart

Slide28Systemic and PulmonaryCirculation

Slide29Heart Skeleton• Consists of plate of fibrous connective tissue between atria and ventricles • Fibrous rings around valves to support • Serves as electrical insulation between atria and ventricles • Provides site for muscle attachment

Slide30Cardiac Muscle• Elongated, branching cells containing 1-2 centrally located nuclei • Contains actin and myosin myofilaments • Intercalated disks : Specialized cell-cell contacts • Desmosomes hold cells together and gap junctions allow action potentials • Electrically, cardiac muscle behaves as single unit

Slide31Conducting System of Heart

Slide32Electrical Properties• Resting membrane potential ( RMP ) present • Action potentials – Rapid depolarization followed by rapid, partial early repolarization.  Prolonged period of slow repolarization which is plateau phase and a rapid final repolarization phase – Voltage-gated channels

Slide33Action Potentials inSkeletal and Cardiac Muscle

Slide34SA Node Action Potential

Slide35Refractory Period• Absolute : Cardiac muscle cell completely insensitive to further stimulation • Relative : Cell exhibits reduced sensitivity to additional stimulation • Long refractory period prevents tetanic contractions

Slide36Electrocardiogram• Action potentials through myocardium during cardiac cycle produces electric currents than can be measured • Pattern – P wave • Atria depolarization – QRS complex • Ventricle depolarization • Atria repolarization – T wave: • Ventricle repolarization

Slide37Cardiac Arrhythmias• Tachycardia : Heart rate in excess of 100bpm • Bradycardia : Heart rate less than 60 bpm • Sinus arrhythmia : Heart rate varies 5% during respiratory cycle and up to 30% during deep respiration • Premature atrial contractions : Occasional shortened intervals between one contraction and succeeding, frequently occurs in healthy people

Slide38Alterations in Electrocardiogram

Slide39Cardiac Cycle• Heart is two pumps that work together, right and left half • Repetitive contraction ( systole ) and relaxation ( diastole ) of heart chambers • Blood moves through circulatory system from areas of higher to lower pressure. – Contraction of heart produces the pressure

Slide40Cardiac Cycle

Slide41Events during Cardiac Cycle

Slide42Heart Sounds• First heart sound or “lubb” – Atrioventricular valves and surrounding fluid vibrations as valves close at beginning of ventricular systole • Second heart sound or “dupp” – Results from closure of aortic and pulmonary semilunar valves at beginning of ventricular diastole, lasts longer • Third heart sound  (occasional) – Caused by turbulent blood flow into ventricles and detected near end of first one-third of diastole

Slide43Location of Heart Valves

Slide44Mean Arterial Pressure (MAP)• Average blood pressure in aorta • MAP=CO x PR – CO is amount of blood pumped by heart per minute • CO=SV x HR – SV : Stroke volume of blood pumped during each heart beat – HR : Heart rate or number of times heart beats per minute • Cardiac reserve: Difference between CO at rest and maximum CO – PR is total resistance against which blood must be pumped

Slide45Factors Affecting MAP

Slide46Regulation of the Heart• Intrinsic regulation : Results from normal functional characteristics, not on neural or hormonal regulation – Starling’s law of the heart • Extrinsic regulation : Involves neural and hormonal control – Parasympathetic stimulation • Supplied by vagus nerve, decreases heart rate, acetylcholine secreted – Sympathetic stimulation • Supplied by cardiac nerves, increases heart rate and force of contraction, epinephrine and norepinephrine released

Slide47Heart Homeostasis• Effect of blood pressure – Baroreceptors monitor blood pressure • Effect of pH, carbon dioxide, oxygen – Chemoreceptors monitor • Effect of extracellular ion concentration – Increase or decrease in extracellular K +  decreases heart rate • Effect of body temperature – Heart rate increases when body temperature increases, heart rate decreases when body temperature decreases

Slide48Baroreceptor and ChemoreceptorReflexes

Slide49Baroreceptor Reflex

Slide50Chemoreceptor Reflex-pH

Slide51Effects of Aging on the Heart• Gradual changes in heart function, minor under resting condition, more significant during exercise • Hypertrophy of left ventricle • Maximum heart rate decreases • Increased tendency for valves to function abnormally and arrhythmias to occur • Increased oxygen consumption required to pump same amount of blood