Compendium 6 Cardiovascular System Notes PDF

Compendium 6 Lecture 1 Components of the cardiovascular system - Heart - A pump used to generate pressure in the blood to move it around the body - Blood vessels - In the form of arteries, veins and capillaries - Form the conduits to carry the blood around the bo...

Compendium 6 Lecture 1 Components of the cardiovascular system - Heart - A pump used to generate pressure in the blood to move it around the body - Blood vessels - In the form of arteries, veins and capillaries - Form the conduits to carry the blood around the body - Blood - Carries the substances or material either dissolved or suspended in it and takes it from one location to another or distributes throughout the body Functions of the cardiovascular system - Transport - Gases - Oxygen, carbon dioxide, nitrogen - Nutrients - Glucose, amino acids, viamins, proteins and lipids - Metabolic waste - Urea, uric acid, creatine, ammonium ions - Regulatory molecules - Hormones, enzymes - Processed molecules - Proteins, enzymes, carbohydrates, lipids - Protection - Inflammation - Phagocytosis - Antibodies - Platelets for clotting - Regulation - Fluid balance - pH - Body temperature - Blood pressure - Exchange between blood, extracellular fluid and cells Heart - Function - Pump - Generates pressure in the blood which moves blood through the blood vessels - The heart is a vital organ, it is pumping before birth - Routs blood - Separate pulmonary and systemic circulation - This is caused by its specific design separating the deoxygenated blood from the oxygenated blood - One way flow - Caused by pressure - Regulates blood supply - Effected by cardiac output - The heart matches the needs of the body (homeostasis) - Protection - Rib cage, protective membranes, fluid - Pericardium - Location - Located in the thoracic cavity, obliquely in the mediastinum, medial to the two lungs and superior to the diaphragm - It is the size of a closed fist and weighs about 300g (250-350) - Females generally smaller and proportionate to the size of the person - Blunt cone shaped 2/3^rd^ towards the left side of midline - The rounded end is the apex, anteriorly and interiorly pointed, above the diaphragm - Broader end is the base, directed posteriorly and slightly superiorly - Sits between the second rib and the 5^th^ intercostal space Pericardium - Fibrous pericardium: tough fibrous outer layer which prevents over distension (overfilling) and it acts as an anchor by connecting it to adjoining tissue - Serous pericardium: thin, transparent inner layer, simple squamous epithelium - Parietal: lines the fibrous outer layer - Visceral: covers the hearts surface (similar in nature to cling film) - The two are continuous and have a pericardial cavity between them filled with pericardial fluid (the pericardial fluid reduces friction and distributes pressure on the heart) - They are protective - The pericardium is attached to the large blood vessels too (aorta and pulmonary trunk) - An infection of the pericardia is called pericarditis Morphology - Anterior and posterior side - Major vessels - Sulci (grooves) - Coronary sulcus - Separates the atria and ventricles - Anterior interventricular sulcus - Separates the right and left ventricle on the anterior side - Posterior interventricular sulcus - Separates the right and left ventricle on the posterior side - Pericardial and epicardial fat - Pericardial fat - Between the visceral and parietal pericardium - Epicardial fat - Between outer layer of myocardium and visceral layer of pericardium (epicardium) - Superior chambers (collecting) -- atria - Walls are thinner - Inferior chambers (discharging) -- ventricles - Walls are thicker Heart wall - Three layers of tissue - Epicardium -- serous membrane, simple squamous epithelium over areolar tissue, smooth outer surface of the heart (visceral pericardium) - Myocardium -- middle layer, thickest layer, composed of cardiac muscle cells, contractability, branched cells, uninucleate - Endocardium -- smooth inner surface of heart chambers, simple squamous epithelium over areolar tissue, covers valve surface and continuous with endothelium, very smooth Heart anatomy - Interventricular septum: the separation between the two ventricles - Interatrial septum: the wall between the atria, contains a depression, fossa ovalis, a remanent of the foetal opening (foramen ovale) between the atria - The left ventricle wall is much thicker than the right ventricle wall - Pectinate muscles: muscular ridges in auricle and atrial walls which allow for the stretching of the muscle when blood is coming in and helps in contraction - Trabeculae carnae: muscular ridges and columns on the inside of the ventricle wall which create turbulence in the blood Chambers - Right atrium - Thin walled receiving chamber, most part on the posterior side - Auricles are extensions to increase volume - Contain pectinate muscles for large force of contraction - Receives deoxygenated blood returning from the blood through three openings - Superior and inferior vena cava, coronary sinus - Right ventricle - Pumping chamber, mostly on the anterior side - Thicker walled than the atria - Receives deoxygenated blood from the right atrium - Opens to the pulmonary trunk - Contains trabeculae carnae - Left atrium - Thin walled receiving chamber, most part on posterior side, forms the hearts base - Auricles are extensions to increase volume - Contain pectinate muscles for large force of contraction - Receives deoxygenated blood returning from the lungs through 4 openings - Four pulmonary veins - Left ventricle - Pumping chamber, forms apex and posteroinferior aspect - Thickest walled chamber of the heart - Receives oxygenated blood from the left atrium - Opens to aorta - Contains trabeculae carnae Great blood vessels of the heart - Blood into the heart: - Into the right atrium: by the superior and inferior vena cava from systemic circulation and coronary sinus from coronary circulation (deoxygenated) - Into the left atrium: by left and right pulmonary veins from pulmonary circulation (oxygenated) - Blood out of the heart: - Out of right ventricle: by pulmonary trunk (which splits into 2 pulmonary arteries, one for each lung) to pulmonary circulation (deoxygenated) - Out of left ventricle: by aorta to systemic circulation (oxygenated) Valves of the heart - Atrioventricular valves - Valves between atria and ventricles - Valves have leaf-like cusps - The cusps are attached to papillary muscles by tendons -- chordae tendineae - Open valves have a canal -- atrioventricular canal - Right side has three cusps (tricuspid, right AV valve) - Left side has 2 cusps (bicuspid, left AV valve) - When the valve is open blood flows from atrium to ventricle - When it is closed blood exits the ventricle and enters the atrium - Semilunar valves - Valves at the base of large blood vessels (exit of ventricles) - Valves are cup shaped - Pulmonary SL valve is at the base of the pulmonary trunk - Aortic pulmonary valve is at the base of the aorta - When the cups are filled the valves close preventing the backflow of blood into the heart - When cups are empty the valve is open and blood can flow freely out of the heart - Very thin membrane however very strong in nature - Function - Valves -- prevent backflow of blood (when asked about this be sure to be specific about which spaces the blackflow would occur in and from and the relevant valve) - Chordae tendineae -- strings connecting valve cusps to papillary muscles to prevent the atrioventricular valves from bulging into the aorta - Papillary muscles -- pillar like muscles in ventricles which prevent the prolapse of atrioventricular valves Blood flow - Superior and inferior vena cava and coronary sinus -\> right atrium -\> tricuspid valve \--\> right ventricle -\> pulmonary semilunar valve -\> pulmonary trunk -\> pulmonary arteries -\> lung tissue -\> pulmonary veins -\> left atrium -\> bicuspid valve -\> left ventricle -\> aortic semilunar valve -\> aorta -\> coronary arteries or body tissues Pump - Pulmonary circulation -- deoxygenated blood is transported to the lungs for oxygenation then returned to the heart meaning that there is double circulation for one cardiac cycle - Deoxygenated blood enters the right atrium and flows into the right ventricle - Exits through the pulmonary trunk - The pulmonary trunk divides into left and right pulmonary arteries - The blood travels to the left and right lung for gas exchange - Oxygenated blood travels in the pulmonary veins back to the heart and enters the left atrium - Systemic circulation -- oxygenated blood is transported to the body tissues and then returned to the heart - Oxygenated blood enters the left atrium and blood flows into the left ventricle - Left ventricle contracts and pushes blood out of the heart through the Aorta - The aorta branches into the ascending aorta, aortic arch and descending aorta - Blood is delivered to all cells in the body for gas/nutrient/fluid exchange - Deoxygenated blood travels back to the heart and re-enters the right atrium through the vena cava - Coronary circulation is a part of systemic circulation which occurs only to the heart Lecture 2 Cardiac cycle - Contraction of the heart produces the pressure - Blood moves through the circulatory system from areas of higher to lower pressure - Cardiac cycle - Repetitive contraction (systole) and relaxation (diastole) of the heart chambers -- moves blood through the heart and body - Blood flow is proportional to the metabolic needs of tissues - The brain, kidneys, liver and exercising skeletal muscles have very high metabolic needs - Cardiac output = heart rate x stroke volume - Stroke volume: the amount of blood ejected from the heart - Heart rate: the number of times the heart beats in a minute - Cardiac output is calculated in millilitres per minute, in a normal adult this is 5-6L/minute at rest - Nervous system control - The autonomic nervous system maintains blood pressure and thus blood flow - Rerouting blood flow e.g. increase in blood pressure with exercise - Rerout blood flow away from viscera and skin and towards the brain and the cardiac muscles in response to blood loss/injury - Hormonal control - Epinephrin (adrenaline) from the adrenal gland, has the ability to increase heart rate and stroke volume by triggering vasoconstriction as a response to stress Conducting systems - Cardiac conducting system - Internal pacemaker and nerve like pathways through the myocardium - Action potential - A rapid change in membrane potential which acts as an electrical signal/impulse - Action potentials spread through the conducting system of the heart to all cardiac muscle cells -- as a result the cardiac muscle cells contract 'pumping' the blood - The heart can generate its own action potentials - Auto-rhythmicity - Repetitive contractions caused by autorhythmic contractile cells - Sinoatrial nodes -- pacemaker: these are located in the atrial wall. Its function is to create action potentials at regular intervals - Atrioventricular nodes: this is located at the junction of the atrium and ventricle - Atrioventricular bundle: nerve tissue in the form of atrioventricular bundle that continues from the node - Right and left bundle branches: once the bundle passes through the atrioventricular septum it splits into two bundle branches which go to the apex of the heart and through the myocardium and move up to the atrioventricular wall - Purkinje fibres in ventricular walls: the branches given off by the right and left bundle branches and re purkinje branches (maybe look these definitions up in the text book) Blood composition - Life sustaining fluid - Blood is the most commonly studied tissue for disease diagnosis - If blood is left to stand or centrifuged it separates into: - Plasma 55% - Extracellular matrix of blood - 91% water - 7% proteins - Albumins (58%): very large proteins which help in controlling osmotic balance - Globulins (38%): transport proteins which carry lipid soluble molecules and antibodies - Fibrinogen (4%): fibrous proteins which aid clotting - 2% other solutes - Ions (Na, K, Ca, Mg) - Nutrients (glucose, amino acids, lipids, cholesterol) - Waste products - Gases - Regulatory substances - Buffy Coat - White blood cells (5-10 thousand/cubic mm) - Platelets (250-400 thousand/cubic mm) - Formed elements 45% (Haematocrit) - Red blood cells (4.2-6.2 million/cubic mm) - Blood is a connective tissue meaning it has few cells with lots of extracellular matrix - In the context of blood the cells are the red and white blood cells which form the formed elements and buffy coat - Usually males have 5-6L of blood while females have 4-5L - The pH of blood is 7.35-7.45 Blood cells - Erythrocytes - Red blood cells - Biconcave disc shaped - 7.5um - Non nucleate with no organelles therefore it can not reproduce and has a fixed lifecycle of 120 days - By having no nucleus or organelles it increases the surface area to volume ratio helping it to carry more oxygen - Contains haemoglobin, a pigmented protein, haemoglobin contains iron - Carries oxygen -- from lungs to tissues, 1.5% dissolved in plasma and 98.5% attached to haemoglobin - Carries carbon dioxide -- from tissues to the lungs, 7% in plasma, 23% is attached to haemoglobin, 70% as HCO3 (bicarbonate ions) - Leukocytes - White blood cells - A high white blood cell count could mean there is an infection in the body - Complete cells with uncle and organelles - Various types e.g. neutrophils, lymphocytes, monocytes, eosinophils, basophils - Mainly help in protection -- phagocytosis, immune response (cell mediated and antibody mediated), develop into macrophages and release histamines ect. - Platelets - Platelets are not true cells but cytoplasmic fractions of very large cells - Important for clotting blood - We can bleed to death from minor cuts if there are no platelets - When a blood vessel is damaged the platelets stick to the fibroin and create a plug/clot stopping blood flow Blood vessels - Arteries - Take blood away from the heart - Contain blood under pressure - Elastic: the large arteries like the aorta and pulmonary trunk, these are elastic so that they can withstand the high pressure caused by their proximity to the heart - Muscular: facilitates vasoconstriction and vasodilation - Arterioles: smaller arteries which feed into capillaries - Precapillary sphincters - reduce blood flow to certain areas when required so that blood can be directed to essential areas - Capillaries - Site of exchange with tissues (interstitial fluid) - Veins - Cary blood towards the heart - Blood is not under pressure - Thinner walls than arteries, contains less elastic tissue and less smooth muscle - The types of vains are venules, small, medium, large, venules are the smallest Histology of blood vessels - Tunica intima (interna): simple squamous endothelium, basement membrane, lamina propria then elastic tissue are the layers of the interna, the interna is closest to the lumen - Tunica media: smooth muscle cells and elastin arranged circularly - Smooth muscle changes the diameter of the lumen - Elastic tissue allows for distension and recoil - Vasoconstriction: smooth muscles contract, there is a decrease in blood flow - Vasodilation: smooth muscles relax, there is an increase in blood flow - Tunica externa (adventitia): connective tissue transitions from dense to loose connective tissue as it merges with surrounding tissue - Nerves and blood vessels pass through the tunica externa as the smooth muscle needs its own blood supply - Lumen: the inside of the blood vessel, where the blood flows - These are the typical features of a blood vessel but depending on the type it may vary to suit the vessels specific needs Blood vessels comparison table Arteries Veins -------------------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------------- Carries blood away from the heart to the tissues Carries blood to the heart from the tissues Located deep in the muscle Located closer to the surface of your body Have very thick walls Have thinner walls than arteries Carry mainly oxygenated and some deoxygenated blood (pulmonary and umbilical artery) Carry mainly deoxygenated and some oxygenated blood (pulmonary and umbilical vein) Have no valves due to the high pressure valves are not required Have valves to prevent the backflow of blood as there is little pressure gravity may try and pull the blood backwards Carry blood under very high pressure Carry blood under very low pressure Round lumen (holds its shape) Flat lumen (looks collapsed) Capillaries - Smallest of the 3 blood vessel types - The capillary wall consists of endothelial cells (simple squamous epithelium) basement membrane and a delicate layer of loose connective tissue - Continuous: no gaps between the endothelial cells, less permeable to large molecules as other types of capillaries e.g. muscle and nervous tissue - Fenestrated: have pores in endothelial cells called fenestrae, these are highly permeable e.g. intestinal villi, glomeruli of kidney - Sinusoidal: large diameter, irregular incomplete wall of endothelial cells, less basement membrane e.g. endocrine glands, liver (as large molecules cross their walls) - Capillaries only have tunica intima, no media or externa - Capillaries have a diameter of 7-9 microns compared to a red blood cell which has a diameter of 7.5 microns Capillary exchange - In order for exchange to occur the cells must bath in interstitial fluid (extracellular fluid) - A substance cant just go from capillary to cell, it must pass through the interstitial fluid - Transport by diffusion in and out of cells requires a pressure gradient - Interstitial fluid needs constant turnover - Source and sink - As the cells are metabolising they are using oxygen so the concentration of oxygen is constantly decreasing but as freshly oxygenated blood is constantly flowing there is a consistent supply of oxygenated blood creating a concentration gradient encouraging the flow of oxygen out of blood vessels, into the interstitial fluid and inter the cells - As the cells are metabolising they are producing carbondioxide so the concentration of carbon dioxide is constantly increasing but as freshly oxygenated blood with low levels of CO2 is constantly flowing there is a consistent supply of blood creating a concentration gradient encouraging the flow of carbon dioxide out of cells, into the interstitial fluid and inter the blood - Capillary exchange: the movement of substances into and out of capillaries - Diffusion: oxygen, hormones and nutrients diffuse from high concentration in the capillary to low concentration in the interstitial fluid - Lipid soluble substances such as O2, CO2, steroid hormones and fatty acids diffuse through the plasma membrane of endothelial cells - Water soluble molecules such as glucose and amino acids diffuse through intercellular spaces or through fenestrations of capillaries - As there are very small spaces between cells, very few molecules can pass for example blood brain barrier (specialised capillaries only allow certain substances into the brain environment) - There are large spaces between endothelial cells so that proteins of whole cells can pass through for example in the liver or spleen Lymphatic system - Lymphoid organs - Spleen, thymus, tonsils - Lymphoid tissues and cells - MALT, Peyer's patches, lymphocytes, B and T cells - Lymph: the fluid which passes through the vessels of this system - Lymphatic ducts, trunks, vessels and capillaries - Lymph nodes The link between cardiovascular and lymphatic systems - Capillary permeability, blood pressure and osmotic pressure effect the movement of fluid from capillaries - Fluid moves out of capillaries and into interstitial space and most returns to the capillaries (osmotic pressures) - The fluid which remains in the tissues is picked up by the lymphatic capillaries and eventually returned to venous circulation - If the lymphatic system did not pick it up there would be fluid accumulation in the area and swelling - If it was not returned by the lymphatic system the blood could thicken and reduce in volume - The lymphatic system is vital for homeostasis of the blood and circulatory system - Maintains blood volume, pressure and fluid balance - Oedema: swelling caused by excess fluid in body tissues (interstitial space) - This can be caused by problems with capillaries, heart failure, kidney disease, liver problems, pregnancy, problems with the lymphatic system, standing or walking in hot weather and eating too much salt - If capillaries become leaky to blood, proteins can leak into the interstitial fluid. This increases the osmotic pressure (osmolarity) outside of the capillary and draws more fluid out of the capillary and into the interstitial fluid Tutorial notes 1. Define pulse The pressure caused by the injection of blood from the left ventricle 2. you can only feel pulse in certain spaces because if there is tissue (not bone) the blood vessel will just press further down and in the particular areas where a pulse can be found the blood vessel is big enough for a pulse to be felt. Blood vessel must be superficial 3. the tongue has its own pulse Pulse point used: neck ------------------------ ----- 1 92 2 90 3 90 Total 272 Average 91 Experiment HR (BPM) SV ml x min L x min ------------ ---------- ---- ---------- --------- Rest 56 70 3920 3.92 2 min 76 70 5320 5.32 5 min 112 70 7840 7.84 1 min post 100 70 7000 7.00 5 min post 68 70 4760 4.76 3\. Yes, we noticed this change, in 1 minute slow decrease but after 5mins heart rate had returned to normal 4\. To increase generation off ATP 5\. 7.84 - 3.92 = 3.92 3.92/3.92 = 1 6\. No because stroke volume increases as we exercise Station 1 1. bicuspid and tricuspid valves, aorta, pulmonary trunk station 2 2. because the left ventricle pumps blood to the whole half compared to the right which pumps blood only to the lungs 3. the most superior part of the heart is the aorta