1 / 50

Circulation

Circulation. Chapters 13 and 14. Circulatory System. Transportation nutrients, metabolic wastes (excretion), water, ions and respiratory gases (O 2 , CO 2 ), Regulatory hormonal – transportation of hormones from endocrine glands to target tissues

pete
Télécharger la présentation

Circulation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Circulation Chapters 13 and 14

  2. Circulatory System • Transportation • nutrients, metabolic wastes (excretion), water, ions and respiratory gases (O2, CO2), • Regulatory • hormonal – transportation of hormones from endocrine glands to target tissues • temperature – blood shunting to conserve or dissipate heat through the skin • Protection • blood clotting – protects against blood loss • immunity – leukocytes protect against disease

  3. Subdivisions • Cardiovascular system • heart and blood vessels • transport blood • Lymphatic system • lymph vessels and lymphoid tissues (spleen thymus, tonsils and lymph nodes) • transport lymph

  4. Cardiovascular System • Blood • transport medium (cells suspended in fluid) • Heart • pump: forces blood through BV’s • Blood vessels • tubing that carries blood (60,000 miles)

  5. Blood • Transport medium for gases, nutrients, wastes etc. • Volume • Women = 5 liters • Men = 5.5 liters • Blood is composed of: • Plasma (55% of blood volume) • fluid portion • Formed Elements (45%) • cells and cell fragments Fig 13.1

  6. Plasma • Water (90%) • dissolves materials (gases, nutrients, etc.) • acts as fluid medium for transport of blood cells and plasma proteins • Proteins (7-9%) • Maintain osmotic pressure of blood (albumins) • Lipid transport (globulins) • Immunity (antibodies, complement proteins) • Clotting factors • Various enzymes

  7. Formed Elements • Erythrocytes • Red Blood Cells • Leukocytes • White Blood Cells • Thrombocytes • Platelets Fig 13.3

  8. Erythrocytes • thin, disc-like cells • 25-30 trillion RBCs circulating at a given time • Lack nuclei and mitochondria • anaerobic respiration only • transport respiratory gases (mainly O2) Fig 13.3

  9. Erythrocytes • RBCs contain Hemoglobin • protein with 4 heme units • heme contains iron • reversibly binds O2 • Hemoglobin changes color when bound to O2 • unbound - dark maroon • bound - bright red Fig 16.33

  10. Leukocytes • Immunity • ability to resist or destroy harmful foreign invaders or abnormal cells • Functions • destroy pathogens • bacteria, viruses, protozoans and worms • destroy cancer cells • remove dead or injured cells • wound healing

  11. Leukocyte Types • Granulocytes • cytoplasmic granules • eosinophils • enhance allergic conditions chemically attack parasites (worms) • basophils / mast cells • promote inflammation response • neutrophils • phagocytes (devour pathogens and dead cells) Fig 13.3

  12. Leukocyte Types • Agranulocytes • no cytoplasmic granules • monocytes • circulating phagocytes • differentiate into macrophages in tissues • lymphocytes • found mainly in lymphatic system • specific immune responses • B Lymphocytes - produce antibodies • T Lymphocytes - destroy virally infected or cancerous cells Fig 13.3

  13. Platelets (Thrombocytes) • cell fragments from megakaryocytes in myeloid tissue • contain actin and myosin (contraction) • Formation of a blood clot to stop bleeding Fig 13.3

  14. Blood Clot Formation • platelets touch underlying collagen in connective tissue • secrete chemical messengers and “glue” • messengers induce vasoconstriction • decrease blood flow to damaged vessel • formation of platelet plug • platelets stick to collagen and to each other

  15. Blood Clot Formation • enzymatic cascade of clotting factors occurs • prothrombin (inactive enzyme)  thrombin (activated enzyme) • catalyzes fibrinogen (soluble)  fibrin (insoluble) • forms protein meshwork over the platelet clot • platelets contract to seal the breach Figs 13.7, 13.8

  16. The Heart • hollow, muscular organ • located in center of thoracic cavity • pumps constantly • variable rate Fig 13.10

  17. Blood Circuits • Pulmonary circuit • from heart (rt)  lungs  heart (left) • gas exchange with atmosphere • release CO2, pick up O2 • Systemic circuit • from heart (left)  tissues  heart (rt) • gas exchange with tissues • release O2, pick up CO2 Fig 13.9

  18. Heart Anatomy:Chambers • Four chambers • Atria (auricles) • receive blood from veins • Ventricles • pump blood into arteries Fig 13.10

  19. Cardiac Muscle • found in myocardium • striated (sarcomeres) • single nucleus in cells • fibers linked by intercalated disks • electrical synapses • allow linked fibers to contract as a unit • Atrial and ventricular fibers not linked by intercalated disks • allows atria and ventricles to contract separately Fig 12.31

  20. Heart Anatomy:Interventricular Septum • Interventricular septum • divides heart into two halves • Right side pumps deoxygenated blood • Left side pumps oxygenated blood Fig 13.10

  21. Heart Anatomy - Valves • Atrioventricular valves • Right (tricuspid) • Left (bicuspid) • Allow blood to flow from atrium to ventricle only • Chordae tendinae attached to papillary muscles • prevent valves from everting during ventricular contraction Fig 13.10

  22. Heart Anatomy - Valves • Semilunar valves • Pulmonary (Right) • Aortic (Left) • at openings of the arteries leaving the ventricles • prevent backflow of blood during ventricular relaxation Fig 13.10

  23. Blood Flow Through the Heart • Deoxygenated blood enters right side through vena cavae • right atrium • right AV valve • right ventricle • pulmonary semilunar valve • pulmonary artery • lungs (pulmonary circuit) Fig 13.9, 13.10

  24. Blood Flow Through the Heart • Oxygenated blood enters left side through pulmonary veins • left atrium • left AV valve • left ventricle • aortic semilunar valve • aorta • tissues (systemic circuit) Fig 13.9, 13.10

  25. Cardiac Cycle • contraction (systole) + relaxation (diastole) of ventricles • lasts 0.8 sec (based on 72 beats/min) Fig 13.12

  26. Cardiac Cycle - Blood Volumes • End-diastolic volume • amt of blood in ventricles at end of diastole • End-systolic volume • amt of blood in ventricles at end of systole • ~1/3 of end-diastolic vol. • Stroke volume (SV) • Amt of blood ejected by ventricles • Equal to EDV – ESV Fig 13.13

  27. Cardiac Cycle - Heart Sounds • “lub” = closing of the AV valves • “dub” = closing of the semilunar valves Fig 13.13

  28. Cardiac Excitation • Heart is generates its own APs • Pacemaker cells • undergo spontaneous depolarizations during diastole • pacemaker potentials • (-60mV  -40mV) Fig 13.17

  29. Pacemaker Potentials • Begins to depolarize due to hyperpolarization of membrane to near -60 mV • “Funny channels” – open in response to hyperpolarization • Allow Na+ and K+ to flow (depolarize) • Triggers opening of “slow” Ca2+ channels (further depolarization) • Reaches threshold for other v.g. Ca2+ channels (“fast channels”) • Ca2+ flows in • rapid depolarization and overshoot • Repolarized by opening of v.g. K+ channels and outflow of K+. Fig 13.17

  30. Pacemakers • Sinoatrial (SA) Node • pacemaker of the heart • Atrioventricular (AV) Node • Delays conduction to ventricles • Bundle of His • conducts signal through interventricular septum • Purkinje fibers • conduct signal up lateral walls of ventricle Fig 13.19

  31. Path of Cardiac Excitation • SA node cells produce APs • Atrial fibers activated • atrial contraction • APs excite AV node • delay (complete atrial contract) • APs of AV node travel down AV bundle to apex of heart • signal conducted to Purkinje fibers throughout ventricles • Myocardial fibers activated • ventricular contraction Fig 13.19

  32. Myocardial Action Potentials • Prolonged action potential duration • Influxof Na+ - depolarization • Plateau phase due to Ca2+ influxand slow opening of K+ channels • Repolarization by delayed opening of v.g. K+ channels • Prolonged refractory period ensures pumping action Fig 13.18, 13.20

  33. Cardiac Output • Amount of blood pumped by the heart in one minute • heart rate (beats/min) X stroke volume (ml) • At rest, HR = 70 bpm, SV = 70-80 ml • Cardiac Output = 5.0 - 5.5 L/min • Heart pumps entire blood volume each min. • During exercise can increase 4-5x to 25 liters/min.

  34. Heart Rate Regulation • Parasympathetic nervous system • Slows HR • Sympathetic nervous system • Speeds up HR • Hormones (Epinephrine) Fig 14.1

  35. Stroke Volume Regulation • end-diastolic volume • ↑EDV, ↑SV • function of venous return • total peripheral resistance • ↑Resistance, ↓SV • Function of blood vessel diameter

  36. Stroke Volume Regulation • contractility • function of sarcomere length in muscle fibers • sympathoadrenal stimulation (↑ Ca2+ concentrations) Figs 14.2, 14.3

  37. Blood Vessels • Tubes that conduct blood • Arteries • Aterioles • Capillaries • Venules • Veins Fig 13.25

  38. Blood Pressure • Pressure blood exerts on blood vessel walls • produced by heart contractions • main driving force for the flow of blood through the blood vessels • decreases as blood moves further from the heart Fig 14.15

  39. Arteries • Large vessel receiving blood from the heart • Functions • rapid transport of blood • large radius, high pressure • pressure reservoirs • walls expand upon systole • recoil during diastole maintains blood flow Fig 13.25

  40. Arterial Blood Pressure • Systolic blood pressure • pressure of blood in arteries during ventricular systole • Diastolic blood pressure • pressure of blood in arteries during ventricular diastole • Indicates • blood flow to the body • work load of the heart Fig 14.15

  41. Arterial Blood Pressure Regulation • Blood pressure monitored by baroreceptors in carotid sinuses and aorta • Signals sent to medulla • cardiac + vasomotor centers • response sent out via autonomic MNs • sympathetic -  HR, vasoconstriction • parasympathetic -  HR, vasodilation Figs 14.25, 14.26

  42. Arterioles • Major resistance vessels •  fluctuations in blood pressure btw systole & diastole • Control of perfusion • smooth muscle in vessel walls under autonomic control • vasoconstriction •  diameter,  blood flow • vasodilation •  diameter,  blood flow Figs 13.25, 14.15

  43. Capillaries • Single endothelial cell layer • Connect arterioles to venules • Exchange of materials between blood and interstitial fluid Fig 13.25

  44. Properties of Capillaries • Short diffusion distance • thin capillary walls • narrow diameter • High surface area • extensive branching (close to all cells) • Slow blood flow • increases time for diffusion to occur Fig 14.24

  45. Ultrafiltration • Blood passing through capillaries undergoes ultrafiltration • Blood pressure causes plasma fluid to be pushed out (proteins remain) • As fluid is pushed out, blood osmotic pressure increases • Fluid drawn back into the capillaries when osmotic pressure exceeds blood pressure • More fluid forced out than pulled in Fig 14.9

  46. Venules and Veins • Return blood to the heart after exchanging materials in capillaries • Hold most of the blood in the body • capacitance vessels • regulate rate of blood return to the heart Fig 13.25

  47. Venous Return Venous return • amt of blood veins deliver back to the heart Factors influencing return • pressure gradient • mean pressure is low • vein walls are highly elastic • large radii of veins - little resistance • modified by vasoconstriction

  48. Venous Return • Venous Valves • prevent backflow of blood • Skeletal Muscle Activity • contraction acts to “pump” veins • increases venous return with increased activity Fig 13.28

  49. Lymphatic System • Blood passing through capillaries undergoes ultrafiltration • Net loss of fluid from the blood • Must be returned to the blood Figs 14.9, 14.10

  50. Lymphatic System • Network of vessels • picks up lost fluid (lymph) and returns it to circulation • Pass through lymph nodes • Immune functions • Vessels deposit lymph into subclavian veins Figs 13.34, 13.36

More Related