Chapter 8.1 – Structures of the Circulatory System

1. Chapter 8.1 – Structures of the Circulatory System Pages 268 - 281

2. Introduction: Launch Lab – Watching Blood Flow(Page 267) • Procedure: • Watch the video clip showing blood circulation in the tail of a gold fish. • Answer the analysis question. Circulation in a Goldfish Tail

3. Structures of the Circulatory System • The circulatory system is the transportation system of the body. • 3 Main Functions • Transports gases • Regulates internal temperature • Protects against blood lose and -disease –causing microbes

4. Major Components • 3 Major Components: • The heart – an organ that pushes blood through the body with its pumping action. • The blood vessels – serve as the “roadways” through which the blood moves. • The blood – carries nutrients, oxygen, carbon dioxide, water, wastes and many other materials throughout the body.

5. The Cardiovascular System • Together the heart and the blood vessels are known as the cardiovascular system.

6. The Structure of the Heart • The heart is located on the left side of the chest • The heart has several important functions: • Pumping blood through the body • Keeping oxygen-rich blood separated from oxygen-poor blood • Ensuring that blood only flows in one direction

7. The walls of the heart are made up of cardiac muscle tissue (found only in the heart) • The contractions of the cardiac muscle tissues are rhythmical and involuntary • The muscle cells relax completely for the milliseconds between contraction to prevent muscle fatigue

8. The human heart has 4 chambers: • 2 top chambers are called the atria: right atrium and left atrium – fill with blood from the body or lungs. • 2 bottom chambers are called the ventricles – receive blood from the atria and pump it out to either the body or lungs. • The chambers are separated by a thick wall called the septum

10. Blood Flow through the Heart • Oxygen-poor blood enters the heart from two large vessels, the vena cavae. • Superior vena cava collects blood from tissues in the head, chest and arms • Inferior vena cava collects blood from regions below the chest

11. Oxygen-poor blood flows from the vena cavae into the right atrium • Oxygen-poor blood is then pumped onto the right ventricle • Oxygen-poor blood exits the right ventricle via the pulmonary arteries • Pulmonary arteries carry blood to the right and left lungs for gas exchange

12. Oxygen-rich blood flows from the lungs through the pulmonary veins to the left atrium • Oxygen-rich blood is then pumped into the left ventricle • Oxygen-rich blood exits the heart via the aorta (largest vessel in the body)

13. Valves of the Heart • The heart has four valves to ensure blood flows in the correct direction: • Right atrioventricular valve: • Separates the right atrium and right venticle • Tricuspid valve; made of 3 flaps • Left atrioventricular valve: • Separates the left atrium and left ventricle • Bicuspid valve; made of 2 flaps

14. Atrioventricular valves are held into place by chord-like tendons called the chordaetendinaeto ensure the valves are not pushed back into the atria by flowing blood. • Semilunar valves control the flow of blood into the aorta and pulmonary artery

16. Using blue and red pencils or pens, diagram the pathway of blood through the heart using arrows. Use blue to represent deoxygenated blood and red for oxygenated blood.

17. Blood enters the right atrium through the ________________. • Blood flows from the right atrium into the right ventricle through the _________________. • Blood is pumped from the right ventricle into the pulmonary trunk that splits into the right and left _____________________. • Blood returns from the lungs by way of the right and left ____________________. • Blood enters the ____________________ when it returns from the lungs. • Blood flows past the ________________________ as it enters the left ventricle. • The left ventricle pumps out past the ______________________ into the aorta.

18. The Structure of Blood Vessels • Three types of blood vessels: • Arteries: • carry oxygen-rich blood away from the heart • thick and highly elastic walls • Veins: • carry oxygen-poor blood towards the heart • thinner walls and large inner circumference • have one-way valves to prevent back flow

19. Capillaries: • network of fine vessels where gas and nutrient transfer to tissues occurs. Capillaries join arteries to veins • Capillary walls are a single cell thick

20. Label the diagram • Use blue and red to indicate whether the vessel carries oxygenated blood (red), deoxygenated blood (blue) or both.

21. Compare the structure and function of the three types of blood vessels.

22. The Beating Heart • The stimulus that triggers a heartbeat is an electrical signal that originates from within the heart itself. • The sinoatrial (SA) node is a bundle of specialized muscle tissue that stimulates the muscle cells to contract and relax rhythmically • Located in the wall of the right atrium • SA node is also called the “pacemaker” because it sets the pace for cardiac activity

23. The SA node generates an electrical signal that spreads over the two atria simutaneously. • As the atria contract, the signal reaches the atrioventricular (AV) node. • The AV node transmits the electrical signal through the bundle of specialized fibres called the bundle of His. • The bundle of His relays the signal through two bundle branches that divide into fast-conducting Purkinje fibres • Purkinje fibres initiate the simultaneous contraction of all cells of the right and left ventricles Heartbeat signal

24. ECG • Changes in voltage of the heart can be measured using an electrocardiogram (ECG) • An ECG measures the electrical activity of the heart as it contracts and relaxes • Irregular spikes or changes in the spacing of waves can be used to diagnose different heart conditions

25. Blood Pressure • Blood passing through vessels exerts pressure against vessel walls, called blood pressure • Changes in blood pressure corresponds to phases of the heartbeat • Maximum pressure is called systolic pressure, during ventricle contraction • Lowest pressure is called diastolic pressure, occurs just before the ventricles contract • Sphygmomanometer (blood pressure cuff) measures blood pressure

26. Cardiac Output and Stroke Volume • Cardiac output is the amount of blood pumped by the heart, measured in mL/min • Cardiac output is an indicator of the level of oxygen delivered to the body and the amount of work the body’s muscles can perform • Heart rate is the number of heartbeats per minute • Stroke volume is the amount of blood forced out of the heart with each heartbeat. • cardiac output = heart rate x stroke volume

27. Stroke volume depends on: • How easily the heart fills with blood, related to “stretchiness” of ventricular walls and volume returning to heart from veins • How readily the heart empties, related to the strength of the ventricular contraction • Average person has a stroke volume of 7o mL and a resting heart rate of 70 beats/min • Cardiac output = 70 mL x 70 beats/min = 4900 mL/min • Average person has 5 L of blood in their body; the total volume of blood circulates through the heart about once every minute.

28. Pathways of the Circulatory System • The circulatory system has 3 pathways: • Pulmonary pathway – transports blood between the heart and the lungs • Systemic pathway – moves blood from the left ventricle to the tissues and back to the right atrium • Coronary pathway – provides blood to the heart itself

29. Tracing the Pathways… • Tracing the pathway of blood beginning in right atrium… pulmonarypulmonary  systemic  systemic (to lungs) (to heart) (to tissues) (to heart)

31. Tracing the pathway of blood through coronary… • Heart does not use blood inside chambers to get nutrients/ remove wastes; walls are too thick for diffusion • The heart is covered in a network of vessels • Oxygenated blood is supplied from the coronary artery coming off of the aorta • Deoxygenated blood enters the right ventricle before heading to the lungs.

33. Cardiovascular Disorders and Treatments • Cardiovascular disease is the leading cause of death for Canadians • Can be reduced with lifestyle changes: • not smoking • Eating healthy diet • Exercising • Arteriosclerosis: • thickening of artery walls • Elastic properties diminished

34. Atherosclerosis: • Build-up of fatty deposits on wall of artery • Blood flow is decreased, blood pressure is increased • Especially dangerous in arteries of heart, neck, brain, legs, kidneys • Treated with asprin to prevent platelets from sticking together (clots) • Treated with medication to breakdown existing clots Atherosclerosis

35. Surgical treatments such as angioplasty; permanent stent is inserted into artery to “re-open” passage way Angioplasty

36. Coronary bypass operation – healthy vessels are taken from elsewhere in the body and used to create a new pathway around a blocked vessel. Coronary Bypass Surgery

37. Congenital Heart Defects • Some heart defects are congenital, they are present since birth • Common congenital defects: • walls dividing chambers • valves of the heart • structure of the blood vessels near the heart

38. Heart murmur – describes any misflow of blood through the heart • Ie. One or more of the valves not opening properly • Valve defects can be heard with a stethoscope as a whooshing or rasping sound (caused by blood “leaking” through the valve • Can be also be diagnosed with CT scan, CAT scan, MRI scan by creating a 3D image of the organ Bicuspid/ Mitral valve Regurgitation Mitral Regurgitation Sound Heart Transplant

39. 8.2 – Blood and Circulation Pages 282 - 291

40. The Components of Blood • Blood is considered to be a tissue because it consists of a solid and fluid portion • Plasma – fluid component of blood, making up 55% of volume • Consists of: • dissolved gases • Proteins • Sugars • Vitamins • Minerals • Hormones • Waste products

41. Formed portion – solid component of blood, making up 45% of volume • Consists of: • Red blood cells • White blood cells • Platelets • Formed portion components are produced in the bone marrow, found in the bones. The Components of Blood

42. The Formed Portion of Blood • Red blood cells: • Called erythrocytes (red + cell) • Make up 44% of blood volume • Specialized for oxygen transport • O2 carrying capacity of blood depends of # of RBCs and amount of hemoglobin attached to the RBCs

43. Mature red blood cells are disk-shaped • Lack anucleus • Covered in respiratory pigment hemoglobin • Hemoglobin: • Contains iron • Readily “picks-up” oxygen • Transfers to cells via diffusion • Carries away carbon dioxide

44. Anemia – due to shortage of RBCs or hemoglobin • Reduces the amount of O2 transferred to tissues • Sufferers experience fatigue, may appear pale • Can be caused by an iron deficiency

45. Normal number of red blood cells VS anemic number of red blood cells. Role of Red Blood Cells in Anemia

46. White blood cells: • Called leucoytes • Part of immune system, respond to infection • Make up 1% of blood volume, may double during infection • Contain nuclei • Colourless

47. Types of White Blood Cells: • Granulocytes – can leave the blood stream to destroy bacteria • Monocytes and lymphocytes– found in blood stream, engulf and destroy foreign bodies

48. Platelets: • Fragments of cells • Form when larger cells in marrow break apart • Fragments have no nucleus • Break down quickly in the blood • Play a key role in clotting

49. How a clot is formed: • Blood vessel is injured • Platelets are attracted to the site via chemical response • A buildup of platelets stops the bleeding • Fibrin, strand-like material formed in the blood, reinforces the clot from the inside of the vessel Blood Clotting Animation

50. Plasma • Plasma: • Suspends blood cells • Plays key role in CO2 transport • Contains: • 92% water • 7% proteins • 1% ions • Trace amounts of organic substances