The Circulatory System

1. The Circulatory System Chapter 15

2. The Cardiorespiratory System • Includes function of the heart, blood vessels, circulation, and gas exchange, between the blood and atmosphere. • Heart pumps blood through the body through pathways (arteries, veins, and capillaries) • Blood is enriched with oxygen when it passes through the lungs • As oxygen enters the bloodstream, carbon dioxide leaves it (respiration)

3. The Circulatory System • Course taken by blood through the arteries, capillaries, and veins & back to heart • Uses blood to transport dissolved materials throughout body • Oxygen, carbon dioxide, nutrients, waste • Picks up waste products of cell metabolism & takes to lungs and kidneys (to be expelled from body)

4. The Heart • Two major circulations • Each has its own pump • Both pumps are incorporated into the heart • Location • Middle of chest, behind sternum, within ribcage • Pericardial cavity • Above diaphragm • Structure • Primarily a shell with four chambers inside

5. Heart Facts • Adult human heart approx size of closed fist • About 5 inches long and 3 ½ inches wide • Weighs just less than 1 pound • Beats about 100,000 times each day • Pump about 8,000 gallons of blood through 12,000 miles of vessels each day • Contracts and relaxes 70-80 bpm

6. Structure of Heart • Four cavities • Atria • Form curved top of heart • Ventricles • Meet at bottom of heart to form pointed base • Points toward left side of chest

7. Structure of Heart Left Side Right Side • One ventricle • One atrium • Mitral valve—connects left atrium to left ventricle • One ventricle • One atrium • Tricuspid valve—connects right atrium to right ventricle • Wall, septum, separates right and left sides

8. Structure of Heart • Aorta • heart’s main artery • carries blood away from heart to body’s cells • Pulmonary artery • artery that connects heart to lungs • Two largest veins: • Superior vena cava • Inferior vena cava

9. Heart Anatomy

10. Blood Flow • Two sides of heart are anatomically and functionally separate pumping units • Right side pumps blood through pulmonary circulation • Left side pumps blood through systemic circulation

11. Blood Flow • As heart contracts, it pushes blood though chambers and into the vessels • Nerves connected to the heart regulate the speed of contractions • Greater the activity, faster the heart will pump; faster heart pumps, more oxygen and nutrient are carried throughout body

12. Heart’s Conduction System • Heart’s electrical system • Consisting of specialized cells within heart muscle that carry an electrical signal • Regulates pumping of heart

13. Heart Muscle • Pericardium • Epicardium • Myocardium • Endocardium

14. Blood • Only tissue that flows throughout body • Carries oxygen & nutrients to all parts of body and transports waste products back to lungs, kidneys, and liver for disposal • Essential part of immune system • Crucial for fluid and temperature balance • Hydraulic fluid for certain functions • Highway for hormonal messages • Composed of plasma and billions of cells

15. Plasma • The yellowish, liquid part of blood • River in which blood cells travel • Makes up 55% of total volume • Carries blood cells + • Nutrients (sugars, amino acids, fats, salts, minerals) • Waste products (CO2, lactic acid, urea) • Antibodies • Clotting proteins (called clotting factors) • Chemical messengers (hormones) • Proteins that help maintain body’s fluid balance

16. Blood—RBCs & Hemoglobin • Red Blood Cells (erythrocytes) • Highly specialized cells that have been “stripped” of everything, including nucleus • Major job: transporting oxygen • Percentage of RBCs in total blood volume called hematocrit • Hemoglobin • Special red-colored molecule that fills RBCs • Picks up oxygen in areas where O2 is abundant and releases O2 in tissues where O2 concentration lowest

17. Blood—White Blood Cells • 5 distinct kinds • Neutrophils, monocytes, lymphocytes, eosinophils, basophils • Able to change according to need and situation in body • Can leave blood stream , sliding out through vessel walls & attacking invaders at site of infections

18. Blood—Platelets • Fragments of much larger cell (megakaryocyte) which stays in bone marrow after it differentiates and matures from stem cell • Platelets leave bone marrow & circulate throughout the body • When stimulated by substance from damaged tissue, platelets release substance to help clot blood

19. Blood Vessels • Hollow tubes running throughout the body • 5 types • Arteries • Arterioles • Veins • Venules • Capillaries • Provide 2 measurements: • Pulse • Blood pressure

20. Arteries • Blood vessels that carry blood from the heart to organs & cells • Muscular walls that allow them to dilate or constrict • Arterioles: very small arteries • Largest artery=aorta • Runs from chest into abdomen • Receives blood directly from left ventricle

21. Veins • Blood vessels that carry blood back to heart • Thinner wall • Contain numerous one-way valves (keep blood moving toward heart) • Deep veins in LE surrounded by large muscle groups; compress the deep veins when muscles contract • Contractions in extremities helps propel blood toward heart; increase venous return

22. Veins • Largest vein=superior & inferior vena cava • Bring blood from upper and lower body into right atrium • Venules: smallest veins

24. Capillaries • Tiny, microscopic blood vessels that connect arteries to veins • Responsible for transferring oxygen and nutrients to cells • Wall so thin that O2 passes from arterial blood through them into cells in organs/tissues • Waste products (CO2) pass into capillaries to be carried back by veins to heart/lungs

25. Coronary Arteries • The heart’s own system of blood vessels • Located around heart muscle to provide blood and oxygen to all parts of heart • Two primary coronary arteries branch off into smaller vessels • Right coronary artery: feeds right atrium & ventricle and bottom of left ventricle • Left main coronary artery: supplies blood to rest of heart • Left anterior descending • Circumflex

26. Blood Pressure • Heart pumps blood into arteries; surge of blood filling vessels creates pressure against vessel walls • Pressure measured by 2 numbers: • Systolic: highest pressure in heart • Correlates to ventricular ctx • Average 120 mm/Hg • Diastolic: lowest pressure in heart • Relates to ventricular ctx • Average 80 mm/Hg • Pulse pressure: difference between diastolic and systolic pressures

27. Pulse • Rhythmical beating of heart • Created by alternating expansion and contraction of artery as blood flows through • 7 areas where pulse can be felt • Brachial artery • Common carotid artery • Femoral artery • Dorsalispedis artery • Popliteal artery • Radial artery • Temporal artery

28. Target Heart Rate • Percentage of the maximum heart rate that is safe to reach during exercise • AHA recommends 50-75% for average healthy person • Calculated 220-age • THR is sliding scale that decreases with age • Tool for measuring cardiovascular exercise • Maintain THR for 15-30 min daily health benefits

29. Flow of Blood through Heart • Superior/inferior vena cava • Right atrium • Tricuspid valve • Right ventricle • Semi-lunar valve • Pulmonary artery • Lungs http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_pumping.html

30. Flow of Blood through Heart • Back to heart via pulmonary vein • Left atrium • Bicuspid valve • Left ventricle • Semi-lunar valve • Aorta • Organs in the body

31. Flow of Blood through Heart

34. Can you label the heart?