cardiovascular-and-respiratory-systems.ppt

Cardiovascular system A level PE

1. Component 1 ‒ 1.1.b. Cardiovascular and respiratory systems

2. Learning outcomes By the end of this topic you should be able to demonstrate knowledge and understanding of the cardiovascular and respiratory systems at rest, during exercise and during recovery including: heart rate, stroke volume and cardiac output cardiac cycle – conduction system neural, intrinsic and hormonal regulation of HR the vascular shunt mechanism mechanisms of venous return respiratory volumes mechanics of breathing at rest and during exercise neural and chemical control of breathing gaseous exchange at the alveoli and muscles.

3. Timings Topic Allocated time Heart rate, stroke volume and cardiac output 1 Hour Cardiac Cycle – Conduction System 1 Hour Neural, Intrinsic and Hormonal regulation of HR 2 Hours The Vascular Shunt Mechanism 2 Hours Mechanisms of Venous Return 1 Hour Respiratory volumes 1 hour Mechanics of breathing at rest and during exercise 3 hours Neural and Chemical control of breathing 1 hour Gaseous Exchange at the alveoli and muscles 3 hours Total 15 hours

4. The Cardiovascular system is responsible for delivering oxygen extracted from the air around us to the muscle tissues for respiration. It includes the heart, a dual-action pump, the blood vessels and the blood which actually transports the oxygen. Oxygenated blood exits the left side of the heart and is transported to muscle tissues via the SYSTEMIC circulatory system. Oxygen is released to the muscles and deoxygenated blood returns to the right side of the heart. It then travels to the lungs via the PULMONARY circulatory system to take on more oxygen and the process continues. The circulatory systems

5. The heart is a network of blood vessels, valves and chambers directing blood flow around the circulatory system. The top two chambers are known as ATRIA. They receive blood from the circulatory systems. The bottom two chambers, the VENTRICLES, receive blood from the atria to pump onwards to the next stage of the cycle. Structure of the heart

6. Cardiac cycle The heart is a dual-action pump responsible for the transport of blood around the body. The right and left side of the heart will contract at the same time delivering blood to the two circulatory systems. The right side of the heart to the pulmonary circulatory system and the left side to the systemic circulatory system. ATRIAL SYSTOLE – the phase when both atria contract to force blood into the ventricles through the bicuspid and tricuspid valves. VENTRICULAR SYSTOLE – the phase when both ventricles contract to eject blood into the pulmonary artery and aorta for transportation around the circulatory systems. DIASTOLE – the relaxation phase of the cardiac cycle, no contraction takes place and blood enters the atria from the vena cava and pulmonary vein

7. Conduction system The cardiac cycle is controlled by the conduction system of the heart. The heart is MYOGENIC which means it has the capacity to generate its own electrical impulse. The impulse is transmitted through the cardiac muscle to stimulate contraction. The SINO-ATRIAL (SA) NODE initiates the impulse which is transported through both atria where it is received by the ATRIO-VENTRICULAR (AV) NODE . This causes Atrial Systole. Blood is ejected out of both atria and into the ventricles. The AV node delays the impulse briefly then releases it onwards to the BUNDLE OF HIS . The bundle of His splits the impulse down the left and right bundle branches where they reach the PURKINJE FIBRES . Once the impulse reaches these fibres both ventricles will contract causing the blood to be ejected into the circulatory systems. There is a brief break where no impulse is generated allowing blood to enter the atria.

8. Conduction system STAGE CYCLE / Blood movement CONDUCTION 1 Blood enters the atria from the vena cava and the pulmonary vein. Atria and Ventricles are relaxed DIASTOLE   No impulse 2 Both Atria contract. Blood is forced from the atria to the ventricles.   ATRIAL SYSTOLE Impulse from SA NODE to AV NODE 3 Blood is forced from the ventricles to the Aorta and Pulmonary Artery. VENTRICULAR SYSTOLE AV NODE to BUNDLE OF HIS to  PURKINJE FIBRES

9. Heart rate, stroke volume and cardiac output Definition Rest Maximal Heart Rate The number of beats of the heart per minute 60-75 220 - age Stroke Volume The volume of blood ejected from the left ventricle per beat 70ml/beat 100- 120ml Cardiac Output The volume of blood ejected from the left ventricle per minute 5l/min 20-30l/min Rest Maximal Heart Rate 50 220 - age Stroke Volume 100ml/beat 160- 200ml Cardiac Output 5l/min 30-40l/min Untrained performer Trained athlete

10. Heart rate regulation – neural control SYMPATHETIC NERVOUS SYSTEM The body systems must adapt to the environment around it to allow them to perform as efficiently as possible. When exercise is undertaken, the muscles require greater volumes of oxygen to help in the breakdown of fats and glucose to produce ATP for muscular contractions. The sympathetic nervous system responds by stimulating the SA node to increase heart rate. PARASYMPATHETIC NERVOUS SYSTEM Once exercise has finished and the body begins to recover the parasympathetic nervous system will act to reduce stimulation of the SA node reducing heart rate. This will eventually return to resting levels.

11. Sympathetic nervous system SYMPATHETIC NERVOUS SYSTEM The sympathetic nervous system is responsible for increasing heart rate. This is controlled by the CARDIAC CONTROL CENTRE situated in the MEDULLA OBLONGATA of the brain. The Cardiac Control Centre receives information from receptors concerning various changes in the body as a result of exercise being undertaken. The CCC then sends impulses down the ACCELERATOR NERVE to increase the firing rate of the SA Node, thus increasing heart rate meaning more oxygen is delivered to the working muscles.

12. RECEPTORS BARO CHEMO PROPRIO DETECT WHAT? INCREASE IN PRESSURE INCREASE IN ACIDITY/ DECREASE IN pH MOVEMENT WHERE? IN THE BLOOD VESSELS IN THE BLOOD IN TENDONS AND MUSCLE FIBRES

13. Parasympathetic nervous system PARASYMPATHETIC NERVOUS SYSTEM The parasympathetic nervous system is responsible for reducing heart rate. This is also controlled by the CARDIAC CONTROL CENTRE situated in the MEDULLA OBLONGATA of the brain. The Cardiac Control Centre receives information from receptors concerning various changes in the body as a result of exercise ceasing. The CCC then sends impulses down the VAGUS NERVE to decrease the firing rate of the SA Node, thus decreasing heart rate meaning less oxygen is delivered to the working muscles.

14. Heart rate regulation – hormonal control In response to exercise the ADRENALIN and NOR-ADRENALIN are released from the ADRENAL GLAND. These hormones have a direct effect on the force of contraction of the heart muscle, thus increasing Stroke Volume and the firing rate of the SA node, thus increasing Heart Rate. The combined effect will increase Cardiac Output and delivery of oxygenated blood to the working muscles.

15. The vascular system The vascular system is a dense network of blood vessels. It includes the blood which travels through the system transporting oxygen, carbon dioxide and essential nutrients throughout the body. The blood vessels include: ARTERIES – transport oxygenated blood from the heart. The largest of these is the AORTA which receives blood from the LEFT VENTRICLE . VEINS – larger blood vessels carrying deoxygenated blood back towards the heart. The largest of these is the VENA CAVA which delivers deoxygenated blood back to the RIGHT ATRIA of the heart.

16. The vascular system ARTERIOLES – smaller arteries which have a large layer of smooth muscle allowing the lumen diameter to be altered.  CAPILLARIES – are vessels of a single layer of cells which penetrate the muscle and organ cells. They allow for gas, nutrient and waste exchange. VENULES – the smaller blood vessels carrying deoxygenated blood back towards the heart.

17. Venous return mechanisms POCKET VALVES – one way valve located in the veins which prevent the backflow of blood. MUSCULAR PUMP – the contraction of skeletal muscle during exercise which compresses the veins forcing blood back towards the heart. RESPIRATORY PUMP – During inspiration and expiration a pressure difference between the thoracic and abdominal cavities is created which squeezes blood back towards the heart. SMOOTH MUSCLE – The layer of smooth muscle in the walls of the veins venoconstricts to create VENOMOTOR TONE maintaining pressure in the vein and thus helping the transport of blood back to the heart. GRAVITY – Blood from above the heart returns towards the heart with the help of gravity.

18. Redistribution of cardiac output Cardiac output at rest is approximately 5 litres per minute . During maximal exercise this can increase to 25-40 litres per minute depending on fitness levels. To further aid performance during exercise the increased cardiac output is redistributed to areas of the body which need it most, namely the working muscles. This is done by the VASCULAR SHUNT MECHANISM . The redistribution of blood is controlled by the VASOMOTOR CONTROL CENTRE in the medulla oblongata. The VCC receives information from CHEMORECEPTORS about increases in blood acidity and BARORECEPTORS regarding pressure changes on arterial walls.  This causes the VCC to alter stimulation of arterioles in different areas of the body via the vasomotor nerves.

19. Vasomotor control VASOCONSTRICTION is where increased stimulation from the vasomotor nerve causes the smooth muscle layer to contract reducing lumen diameter and therefore blood flow. VASODILATION is where decreased stimulation from the vasomotor nerve causes the smooth muscle layer to relax increasing lumen diameter and therefore blood flow.

20. Vascular shunt mechanism Distribution At rest During exercise     To organs   Arterioles Pre-Capillary Sphincters Arterioles   Pre-Capillary Sphincters Vasodilate Relaxed Vasoconstrict Contract   To working muscles     Arterioles Pre-Capillary Sphincters Arterioles Pre-Capillary Sphincters Vasoconstrict Contract Vasodilate Relaxed Effect More blood travels to organs than muscles More blood travels to muscles than organs

21. Structure of the respiratory system The respiratory system has two main functions: Pulmonary ventilation – the inspiration and expiration of air from the atmosphere around us. Gaseous exchange – the extraction of oxygen from the air into the blood stream and then into the muscle tissues. The respiratory muscles work to cause volume changes within the thoracic cavity to cause air to be inhaled and exhaled.

22. Gas transport Blood consists of 55% plasma and 45% blood cells. Once oxygen as passed from the alveoli into the blood it is carried in two ways: 97% combines with haemoglobin to produce oxyhaemoglobin HbO2 3% is dissolved within the blood plasma.

23. Gas transport The waste product of aerobic respiration Carbon Dioxide is also transported in the blood this time in three ways: 70% Dissolved in water and carried as Carbonic Acid 23% Combines with haemoglobin to create Carbaminohaemoglobin 7% Dissolved in blood plasma

24. Breathing frequency, tidal volume and minute ventilation response to exercise There are three main measures of respiration: BREATHING FREQUENCY – represents the number of breaths taken per minute. TIDAL VOLUME – is the volume of air INSPIRED or EXPIRED per breath measured in ml or litres . MINUTE VENTILATION – is the volume of air INSPIRED or EXPIRED per minute measured in ml or litres .

25. Breathing frequency, tidal volume and minute ventilation   Tidal volume Frequency Minute ventilation (Pulmonary) Definition Volume of air breathed in or out per breath Number of breaths per minute Volume of air breathed in or out per minute Resting value 0.5 litres 12 -16 6 – 8 litres Maximal value 3 - 5 litres 40+ 200+ litres

26. Mechanics of breathing: rest The Diaphragm contracts and flattens. External Intercostal muscles contract. Rib cage moves up and out Volume of the Thoracic Cavity increases. Pressure of the Thoracic Cavity decreases. Air moves from higher pressure outside to lower pressure in the lungs. Inspiration

27. Mechanics of breathing: rest The Diaphragm relaxes and returns to a dome shape.  External Intercostal muscles relax. Rib cage moves down and in Volume of the Thoracic Cavity decreases. Pressure of the Thoracic Cavity increases. Air moves from higher pressure inside to lower pressure outside lungs. The process is PASSIVE. Expiration

28. Mechanics of breathing: exercise The Diaphragm contracts and flattens  MORE than at rest. External Intercostal muscles contract  MORE than at rest. Additional muscles are recruited. Sternocleidomastoid, scalenes   and pectoralis minor. Rib cage moves up and out  FURTHER  than at rest. Volume of the Thoracic Cavity increases  MORE than at rest. Pressure of the Thoracic Cavity decreases MORE than at rest. MORE air than at rest  moves from higher pressure outside to lower pressure in the lungs. Inspiration

29. Mechanics of breathing: exercise The Diaphragm relaxes. External Intercostal muscles relax. Additional muscles are recruited. Rectus Abdominus, External Obliques, Internal Obliques contract Rib cage moves down and in FURTHER than at rest. Volume of the Thoracic Cavity decreases MORE than at rest. Pressure of the Thoracic Cavity increases MORE than at rest. MORE  air moves from higher pressure outside to lower pressure in the lungs The process is ACTIVE. Expiration

30. Mechanics of breathing: rest ID: 228014470 . REST EXERCISE INSPIRATION DIAPHRAGM EXTERNAL INTERCOSTALS INCREASE VOLUME OF THORACIC CAVITY DECREASE PRESSURE AIR MOVES IN DIAPHRAGM EXTERNAL INTERCOSTALS CONTRACT HARDER EXTRA MUSCLES GTER INCREASE VOLUME OF THORACIC CAVITY GTER DECREASE PRESSURE MORE AIR MOVES IN EXPIRATION PASSIVE DIAPHRAGM EXTERNAL INTERCOSTALS DECREASE VOLUME OF THORACIC CAVITY INCREASE PRESSURE AIR MOVES OUT INTERNAL INTERCOSTALS CONTRACT RECTUS ABDOMINUS CONTRACTS GTER DECREASE VOLUME OF THORACIC CAVITY GTER INCREASE PRESSURE MORE AIR MOVES OUT

31. Control of breathing: exercise Much like the neural control of the heart, increased contraction of the respiratory muscles during exercise occurs as a response to information received in the receptors. Chemical Control Increased acidity in the blood and decreased pH is detected by the CHEMORECEPTORS.   They send messages to the INSPIRATORY CONTROL CENTRE in the Medulla Oblongata to increase INSPIRATION.

32. Control of breathing: exercise Neural Control Movement in the joints is detected by the PROPRIORECEPTORS.   THERMORECEPTORS detect an increase in temperature which causes an increase in respiratory rate. BARORECEPTORS (stretch receptors) detect stretch in the lungs stimulating the EXPIRATORY CONTROL CENTRE to increase EXPIRATION.

33. Gaseous exchange carbon dioxide: alveoli External respiration There is a low partial pressure of carbon dioxide in the alveoli. High Partial Pressure of carbon dioxide in the pulmonary capillary/blood. Steep concentration gradient between alveoli and capillary Carbon Dioxide diffuses from the blood into the alveoli.

34. Gaseous exchange oxygen: alveoli External respiration There is a high partial pressure of oxygen in the alveoli. Low partial pressure of oxygen in the pulmonary capillary/blood. Steep concentration gradient between alveoli and capillary. Oxygen diffuses from the alveoli into the blood.

35. Gaseous exchange oxygen: Alveoli during exercise External respiration There is a high partial pressure of oxygen in the alveoli. The same as at rest. Due to internal respiration consuming oxygen in the muscle cell there is a Lower Partial Pressure of oxygen in the pulmonary capillary/blood returning to the alveoli. Steeper concentration gradient between alveoli and capillary than at rest. More oxygen diffuses from the alveoli into the blood.

36. Gaseous exchange carbon dioxide: alveoli during exercise External respiration There is a low partial pressure of carbon dioxide in the alveoli. The same as at rest. Due to internal respiration producing more carbon dioxide in the muscle cell there is a higher partial pressure of carbon dioxide in the pulmonary capillary/blood returning to the alveoli. Steeper concentration gradient between alveoli and capillary than at rest. More carbon dioxide diffuses from the blood into the alveoli.

37. Gaseous exchange oxygen: muscle cell Internal respiration There is a high partial pressure of oxygen in the blood. Low Partial Pressure of oxygen in the muscle cell Steep concentration gradient between blood and muscle cell. Oxygen diffuses from the blood into the muscle cell.

38. Gaseous exchange carbon dioxide: muscle cell Internal respiration There is a high partial pressure of carbon dioxide in the muscle cell Low partial pressure of carbon dioxide in the pulmonary capillary/blood. Steep concentration gradient between blood and muscle cell. Carbon dioxide diffuses from muscle into the blood.

39. Gaseous exchange oxygen: muscle cell during exercise Internal respiration There is a high partial pressure of oxygen in the muscle. The same as at rest. Due to internal respiration consuming oxygen in the muscle cell there is a lower partial pressure of oxygen in the muscle cell than at rest. Steeper concentration gradient between blood and muscle cell than at rest. More oxygen diffuses from the blood into the muscle cell.

40. Gaseous exchange carbon dioxide: muscle cell during exercise Internal respiration There is a low partial pressure of carbon dioxide in the blood. The same as at rest. Due to internal respiration producing more carbon dioxide in the muscle cell there is a higher partial pressure of carbon dioxide in the pulmonary muscle cell than at rest. Steeper concentration gradient between alveoli and capillary than at rest. More carbon dioxide diffuses from the blood into the alveoli.

41. Gaseous exchange . FROM TO PARTIAL PRESSUREAT REST DIFFUSION GRADIENT AT REST PARTIAL PRESSURE EXERCISE DIFFUSION GRADIENT EXERCISE Alveoli Capillary Alveoli Capillary EXTERNAL Alveoli Blood Capillary High Low Steep High LOWER STEEPER INTERNAL Blood Capillary Muscle Cell Capillary Muscle DIFFUSION GRADIENT AT REST Capillary Muscle DIFFUSION GRADIENT EXERCISE High Low Steep High LOWER STEEPER

42. Oxygen dissociation from haemoglobin In order for efficient transport of oxygen in the blood it has a high attraction to haemoglobin .  This is known as AFFINITY .   However oxygen must release from haemoglobin when it is required at the muscle cell. During exercise the volumes of oxygen released increases .  As the partial pressure of oxygen in the blood reduces so does the affinity of oxygen to haemoglobin .

43. Bohr's Shift During exercise there is an increase in blood acidity due to the increased production of Lactic Acid and Carbonic Acid . This reduces the blood pH. The reduction in blood pH also causes a reduction in the affinity of blood to haemoglobin .  This allows more oxygen to be released to the muscle cell during exercise. The graph shows the increased release of oxygen during exercise. The graph shifts down and to the right. This is known as BOHR'S SHIFT.

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