Blood Circulation: Components, Function, and Structure

1. 0 Chapter 23 Circulation

2. Standards CORE: • I can describe the components and function of blood. • I can describe structure and function of blood vessels. • I can compare and contrast systemic and pulmonary systems. • I can outline blood flow through the heart. • I can explain why blood pressure is related to overall heath. • I can compare and contrast adult and fetal circulation. ADVANCED: • I can trace a red blood cell through the body and back to its starting point. • I can describe nervous control of the heartbeat.

3. 0 How Does Gravity Affect Blood Circulation? • Few animals seem less alike than the giraffe and the corn snake • Despite their differences they have many features in common • What do you think they have in common??

4. Most animals have a circulatory system that transports O2 and nutrients to cells and takes away CO2 and other wastes • The circulatory system of land animals must deal with the problem of gravity

5. Hank – circulatory system • 23.1 The circulatory system connects with all body tissues • In many animals, microscopic blood vessels called capillaries form an intricate network among the tissues • These capillaries are fed by arteries and empty into veins Red blood cell Nuclei of smooth muscle cells Capillary LM 700 Figure 23.1A

6. Plasma (55%) Constituent Major functions Water Solvent for carrying other substances Salts (ions) Osmotic balance, pH buffering, and nerve and muscle function Sodium Potassium Calcium Magnesium Chloride Bicarbonate Centrifuged blood sample Plasma proteins Osmotic balance and pH buffering Fibrinogen Immunoglobulins (antibodies) Clotting Immunity Substances transported by blood Nutrients (e.g., glucose, fatty acids,vitamins) Waste products of metabolism Respiratory gases (O2 and CO2) Hormones Bloody Blood! STRUCTURE AND FUNCTION OF BLOOD Figure 23.13 (left part) • 23.13 Blood consists of red and white blood cells suspended in plasma • Plasma is about 90% water • And contains various inorganic ions, proteins, nutrients, wastes, gases, and hormones

7. Cellular elements (45%) Functions Number per L (mm3) of blood Cell type Erythrocytes (red blood cells) Transport of oxygen (and carbon dioxide) 5–6 million Centrifuged blood sample Leukocytes (white blood cells) 5,000–10,000 Defense and immunity Lymphocyte Basophil Eosinophil Neutrophil Monocyte Platelets 250,000– 400,000 Blood clotting • Red blood cells (erythrocytes) • Transport O2 bound to hemoglobin • White blood cells (leukocytes) • Function both inside and outside the circulatory system to fight infections and cancer Figure 23.13 (right part)

8. Colorized SEM 3,400 CONNECTION • 23.14 Too few or too many red blood cells can be unhealthy • Anemia is an abnormally low amount of hemoglobin or red blood cells • The hormone erythropoietin regulates red blood cell production • Some athletes artificially increase their red blood cell production, a dangerous practice – why would they want to do this?? Figure 23.14

9. Right atrium Left atrium Semilunar valve Semilunar valve Atrioventricular (AV) valve Atrioventricular (AV) valve Right ventricle Left ventricle THE MAMMALIAN CARDIOVACULAR SYSTEM • 23.4 The human heart and cardiovascular system are typical of mammals • The mammalian heart • Has two thin-walled atria that pump blood into the ventricles • Has thick-walled ventricles that pump blood to all other body organs Figure 23.4A

10. Capillaries of head, chest, and arms Superior vena cava 8 • Blood flow through the human cardiovascular system Pulmonary artery Pulmonary artery Aorta 9 Capillaries of right lung Capillaries of left lung 2 7 2 3 3 5 4 10 4 Pulmonary vein Pulmonary vein 6 1 9 Right atrium Left atrium Left ventricle Right ventricle Aorta Inferior vena cava Capillaries of abdominal region and legs Figure 23.4B 8

11. Capillary Basement membrane Epithelium Valve Epithelium Epithelium Smooth muscle Smooth muscle Connective tissue Connective tissue Artery Vein Arteriole Venule • 23.5 The structure of blood vessels fits their functions • A single layer of epithelial cells forms the walls capillaries • Arteries and veins have smooth muscle and connective tissue Figure 23.5

12. Direction of blood flow in vein Valve (open) Skeletal muscle Valve (closed) Figure 23.9B • Muscle contractions and one-way valves keep blood moving through the veins to the heart

13. Capillary Interstitial fluid Diffusion of molecules Tissue cell • Capillaries are the sites of exchange between blood and interstitial fluid and are one cell layer thick Figure 23.1B

14. Interstitial fluid Iumen Capillary wall Nucleus of epithelial cell Cleft between two epithelial cells of the capillary wall Muscle cell TEM 5,000 Figure 23.12A • 23.12 Capillaries allow the transfer of substances through their walls

15. CONNECTION • Not all of our capillaries can be used at the same time – if they are you will go into shock! • Our body controls entry of blood into capillary networks using sphincters in the arterioles prior to a capillary network • Apart from avoiding shock, when and why would our bodies want to do this?

16. Flow of blood through the heart

17. Atria contract. 2 Heart is relaxed. AV valves are open. 1 Ventricles contract. Semilunar valves are open. 3 Heart Beat, Beat, Beat 23.6 The heart contracts and relaxes rhythmically Figure 23.6 • During diastole blood flows from the veins into the heart chambers • During systole • Contractions of the atria push blood into the ventricles • Stronger contractions of the ventricles propel blood into the large arteries • Cardiac output is the amount of blood/minute pumped into the systemic circuit • Heart valves prevent the backflow of blood 0.1sec Systole 0.3 sec 0.4 sec Diastole

18. Specialized muscle fibers Pacemaker (SA node) AV node Right atrium Right ventricle Apex 1 2 3 4 ECG • 23.7 The pacemaker sets the tempo of the heartbeat • The pacemaker (SA node) generates electrical signals that trigger contraction of the atria • The AV node relays these signals to the ventricles Figure 23.7

19. ECG / EKG • An electrocardiogram (ECG) records the electrical changes in the heart • Heart rate adjusts to body needs

20. Aorta Superior Vena cava Left coronary artery Pulmonary artery Right coronary artery Blockage Dead muscle tissue CONNECTION • 23.8 What is a heart attack? • A heart attack is damage to cardiac muscle usually resulting from a blocked coronary artery Figure 23.8A

21. Smooth muscle Connective tissue Plaque Epithelium LM 60  LM 160  Figure 23.8B Atherosclerosis • In atherosclerosis plaques develop in the inner walls of arteries and can block blood flow

22. Is a serious cardiovascular problem resulting from consistent high blood pressure in the arteries Hypertension

23. 120 Systolic pressure 100 80 Pressure (mm Hg) 60 40 Diastolic pressure 20 0 Relative sizes and numbers of blood vessels 50 40 30 Velocity (cm/sec) 20 10 0 Aorta Vains Arteries Venules Arterioles Capillaries Venae cavae Figure 23.9A • 23.9 Blood exerts pressure on vessel walls • Blood pressure • Is the force blood exerts on vessel walls • Depends on cardiac output and the resistance of vessels • Pressure is highest in the arteries and lowest in the veins

24. Bloodpressure110 systolic70 diastolic(to be measured) Pressurein cuffabove 110 Pressurein cuffat 110 Pressurein cuffat 70 Rubber cuffinflatedwith air 110 110 70 Soundsaudible instethoscope Soundsstop Arteryclosed Artery 2 1 3 4 CONNECTION • 23.10 Measuring blood pressure can reveal cardiovascular problems • Blood pressure is measured as systolic and diastolic pressures Figure 23.10

25. Tissue cells Osmotic pressure Osmotic pressure Venous end of capillary Arterial end of capillary Blood pressure Blood pressure Interstitial fluid Net fluid Movement out Net fluid Movement in • The transfer of materials between the blood and interstitial fluid occurs • By diffusion • By pressure flow through clefts between epithelial cells • Blood pressure forces fluid out of the capillary at the arterial end and osmotic pressure draws fluid at the venous end Figure 23.12B

26. Colorized SEM 3,400 • 23.15 Blood clots plug leaks when blood vessels are injured • When a blood vessel is damaged platelets help trigger the conversion of fibrinogen to fibrin, forming a clot that plugs the leak Figure 23.15B

27. Fibrin clot traps blood cells Platelets adhere to exposed connective tissue Platelet plug forms 1 2 3 The blood-clotting process Epithelium Connective tissue Platelet Platelet plug Figure 23.15A

28. Stem cells Stem cells Basophils Erythrocytes Platelets Eosinophils Monocytes Neutrophils Lymphocytes CONNECTION • 23.16 Stem cells offer a potential cure for blood cell diseases • Stem cells divide in bone marrow to produce all blood cells and may be used to treat some blood disorders Figure 23.15B

30. Fetal Circulation • The fetus does not use lungs for acquiring oxygen. • Why???

32. Placenta - organ responsible for delivery of nutrients, removal of waste products and delivery of oxygenated blood to the fetus via diffusion and active transport mechanisms.  Fetal Circulation

34. Fetal Circulation – 4 differencesAKA: The Fetal Four • Umbilical cord • Umbilical vein (1)- A vessel which delivers oxygenated and nutrient rich blood from the placenta to the fetus. • Umbilical arteries (2) vessels that carries deoxygenated blood from iliac arteries out to the placenta. 2. Venous duct - receives blood from the umbilical vein and directs it to the posterior/inferior vena cava. This venous duct acts as a liver bypass and moves blood into the fetal systemic circulation. Function – to bypass the liver Why bypass the liver??

36. Fetal Circulation 3. Foramen Ovale - an opening between the right atrium and left atrium Function – to bypass the lungs Why bypass the lungs??

37. Fetal Circulation • Ductus Arteriosus - A vessel that connects the pulmonary artery to the aorta. Function – to bypass pulmonary circuit.

40. Lymph System • Is a one way transport system (tissues to blood) • Takes excess fluid from capillary beds of body and returns it to the blood • CONSISTS of lymph veins (have valves) and capillaries • Fluid is called lymph • Joins blood at subclavian vein

41. Main Functions of Lymphatic System • Take up excess tissue fluid • Transport fatty acids (from LACTEAL) • Fight infection (lymphocytes) • lymph system

42. Parts of Lymphatic System 1. LACTEAL: dead ends of lymph vessels in villi of the small intestine. 2. LYMPH NODES - small oval structures that produce and store lymphocytes, filter the lymph of damaged cells and debris. • SPLEEN: stores blood. • THYMUS GLAND -production and maturation of some lymphocytes.