****BIOLOGY-VASCULAR-SYSTEM PRESENTATION

Vascular System

1. Vascular system Prepared by: Jowelson V. Matias

2. LEARNING objectives At the end of the lesson, the students will be able to: Explain the function of vascular system. Discuss the function of the heart and its chambers Classify the function of arteries, capillaries, and veins Differentiate the two pathways of circulation and velocity of blood flow Distinguish the importance of understanding blood pressure and its regulation. Determine the importance of healthy lifestyle to ageing of vascular system Relate the importance of the vascular system to other different organ systems of the body.

3. What is vascular system?

4. The vascular system The vascular/cardiovascular system is the organ system that transports nutrients (digestive products), gases, hormones, and other materials to and from the cells of the body. It also functions in fighting diseases and helps stabilize body temperature and pH to maintain homeostasis.

5. Technology break Search for the main function of the heart and; Give its four (4) chambers and their function.

6. THE ORGANS OF THE VASCULAR SYTEM

7. Heart

8. HEART The heart is the muscular organ that pumps blood to the different parts of the body. It is located at the middle of the chest cavity with its tip or apex slightly tilted towards the left. Its base lies just below the second ribs. The hear is just big as one’s own clenched fist. A sac known as Pericardium enclose it

9. HEART Three layers of tissues form the walls of the heart. Epicardium - outer layer Myocardium - middle layer Endocardium - inner layer

10. chambers of the HEART

11. The chambers of the HEART ATRIUM/ATRIA VENTRICLES

12. valves

13. Technology break Search for 2 common types of arteries, veins, and capillaries.

14. Blood vessels

15. Blood vessels Blood vessels are the network of channels that convey blood to all parts of the body. As the blood travels throughout the body, it remains confined within these blood vessels. Blood vessels are connected to the heart. The “Vena Cava” is the largest vein that is connected to the heart. This vein conveys oxygen-poor blood coming from all parts of the body back to the right atrium. It is divided into two: The superior vena cava and inferior vena cava.

16. Blood vessels AORTA The largest artery. It conveys oxygen-rich blood pumped by the left ventricle to all parts of the body. PULMONARY ARTERY It conveys blood pumped by the right ventricle to the lungs for oxygenation. It branches into two, connecting to each lungs. PULMONARY VEINS It conveys oxygen-rich blood back to the left atrium of the heart

17. Types of Blood vessels

18. Arteries

19. VEINS

20. Capillaries

21. Velocity of blood flow

22. Blood flow Blood flow refers to the movement of blood through the vessels from arteries to the capillaries and then into the veins. Pressure is a measure of the force that the blood exerts against the vessel walls as it moves the blood through the vessels. Like all fluids, blood flows from a high-pressure area to a region with lower pressure. Blood flows in the same direction as the decreasing pressure gradient: arteries to capillaries to veins. The rate, or velocity, of blood flow varies inversely with the total cross-sectional area of the blood vessels. As the total cross-sectional area of the vessels increases, the velocity of flow decreases. Blood flow is slowest in the capillaries, which allows time for exchange of gases and nutrients.

23. Resistance is a force that opposes the flow of a fluid. In blood vessels, most of the resistance is due to vessel diameter. As vessel diameter decreases, the resistance increases and blood flow decreases. Very little pressure remains by the time blood leaves the capillaries and enters the venules. Blood flow through the veins is not the direct result of ventricular contraction. Instead, venous return depends on skeletal muscle action, respiratory movements, and constriction of smooth muscle in venous walls.

24. PATHWAYS OF BLOOD CIRCULATION

25. Pulmonary circulation

26. Systemic circulation

27. Blood pressure

28. Blood pressure Blood pressure is the force exerted by the circulating blood upon the walls of the blood vessels. Blood pressure is obtained using an instrument called “Sphygmomanometer”. Blood pressure is always given as two numbers. One number is written above or below the other number. Both numbers are important. For example, the blood pressure is 120/80. The number above (120) is the systolic pressure and the number below (80) is the diastolic pressure.

29. Blood pressure At rest, the heart beats from 60-70 times per minute. Blood pressure is its highest every time the heart beats (systolic pressure). In between beats, blood pressure falls. This is because every in-between beats, the heart is at rest (diastolic pressure) Blood pressure is also the force that moves the blood from the heart to the different blood vessels. The pressure causes the arteries to rhythmically stretch.

30. Regulation of blood pressure

31. Blood pressure is measured using an automated blood pressure monitor, or manually using a stethoscope and sphygmomanometer. It is given as two values ( e.G.  120/80 mmhg ), measured in “ millimetres of mercury ( mmhg )”: Systolic pressure – the first number (120 mmhg in the example) is the pressure of the blood during the heart contraction (systole). Diastolic pressure – the second number (80 mmhg in the example) is the pressure of the blood when the heart is at rest between heart beats (diastole).

32. SHORT-TERM REGULATION OF BLOOD PRESSURE Short-term regulation of blood pressure is controlled by the autonomic nervous system (ANS). Changes in blood pressure are detected by baroreceptors. These are located in the arch of the aorta and the carotid sinus. Increased arterial pressure stretches the wall of the blood vessel, triggering the baroreceptors. These baroreceptors then feedback to the autonomic nervous system. The ANS then acts to reduce the heart rate via the efferent parasympathetic fibres  ( vagus nerve). This reduces the blood pressure.

33. Decreased arterial pressure is detected by baroreceptors, which trigger a sympathetic response. This stimulates an increase in heart rate and cardiac contractility leading to increased blood pressure. Baroreceptors cannot regulate blood pressure long-term. This is because the mechanism that triggers baroreceptors resets itself once a more adequate blood pressure is restored.

34. LONG-TERM REGULATION OF BLOOD PRESSURE There are several physiological mechanisms that regulate blood pressure in the long-term, the first of which is the renin-angiotensin-aldosterone system (RAAS). Renin-angiotensin-aldosterone system ( raas ) Renin  is a peptide hormone released by the granular cells of the juxtaglomerular apparatus in the kidney. It is released in response to: Sympathetic stimulation Reduced sodium-chloride delivery to the distal convoluted tubule Decreased blood flow to the kidney

35. Renin facilitates the conversion of angiotensinogen to angiotensin I. This is then converted to angiotensin II using angiotensin-converting enzyme (ACE). Angiotensin ii is a potent vasoconstrictor. It acts directly on the kidney to increase sodium reabsorption in the proximal convoluted tubule. Sodium is reabsorbed via the sodium-hydrogen exchanger.  Angiotensin II  also promotes the release of aldosterone. Aldosterone promotes salt and water retention by acting at the distal convoluted tubule to increase expression of epithelial sodium channels. Furthermore, aldosterone increases the activity of the basolateral sodium-potassium atp-ase . This consequently, increases the electrochemical gradient for movement of sodium ions. More sodium collects in the kidney tissue and water then follows by osmosis. This results in decreased water excretion and therefore increased blood volume and blood pressure.

36. Anti-diuretic hormone (ADH) The second mechanism by which blood pressure is regulated is via the anti-diuretic hormone (ADH). It is produced in the hypothalamus and stored and released from the posterior pituitary gland. This is usually in response to thirst or an increased plasma osmolarity. Adh acts to increase the permeability of the collecting duct to water by inserting aquaporin channels (aqp2) into the apical membrane. It also stimulates sodium reabsorption from the thick ascending limb of the loop of henle . This increases water reabsorption thus increasing plasma volume and decreasing osmolarity.

37. Further control of blood pressure Other factors that can affect long-term regulation of blood pressure are natriuretic peptides. These include: Atrial natriuretic peptide (ANP) is synthesised and stored in cardiac myocytes. It is released when the atria are stretched and indicates high blood pressure. Anp acts to promote sodium excretion. It dilates the afferent arteriole of the glomerulus, increasing the glomerular filtration rate (GFR). Moreover, ANP inhibits sodium reabsorption along the nephron. Conversely, ANP secretion is low when blood pressure is low. Prostaglandins act as local vasodilators to increase gfr and reduce sodium reabsorption. Moreover, they act to prevent excessive vasoconstriction triggered by the RAAS and sympathetic nervous system.

38. Ageing and vascular system

39. Vascular changes CARDIAC CHANGES CARDIAC FUNCTION BLOOD PRESSURE

40. activity Direction: Answer the following question comprehensively. What is the importance of understanding blood pressure and its regulation? How does healthy lifestyle help in keeping our vascular system organs stable? How does vascular system help other organ system to function properly?