Canvas Notes - Cardiovascular & Tissue Types PDF

CANVAS NOTES Monday, 29 July 2024 10:58 am Learning outcome Understand Identify structures and functions of the cardiovascular system Trace the blood flow through the vessels and chambers of the heart Describe the intrinsic con...

CANVAS NOTES Monday, 29 July 2024 10:58 am Learning outcome Understand Identify structures and functions of the cardiovascular system Trace the blood flow through the vessels and chambers of the heart Describe the intrinsic conduction system of the heart and how nerve impulses are initiated and propagated through the heart muscle to initiate and sustain the heartbeat Describe the form of an ECG and relate this to events in the intrinsic conduction system of the heart Name disorders affecting the cardiovascular system Differentiate between arteries, veins, and capillaries Describe how blood pressure is controlled and how it can be measured Explain the coronary and foetal circulation TISSUE TYPES Each of the body systems is composed of a group of organs working together to perform a common purpose. e.g. the heart and blood vessels of the cardiovascular alve system work together to pump blood (containing oxygen + nutrients) throughout the body Each organ system is composed of a number of organs performing a specific function within that system e.g. in the cardiovascular system the heart pumps blood (blood contains oxygen) Each organ is composed of two or more tissue Line types TISSUES = a collection of similar cells that act together to perform a function. There are 4 main tissue types in the human body: 1) EPITHELIAL TISSUE Cover + line organs - May be classified according to the d Covered on notes Covered on cheat sheet eoli of the lungs e small intestine together to perform a function. There are 4 main tissue types in the human body: 1) EPITHELIAL TISSUE Cover + line organs - May be classified according to the shape/arrangement of the cells Epithelial tissues come in 4 shapes: 1) squamous (flat, thin + scale-like) Ski 2) Cuboidal (square + cube-like) mo 3) Columnar (tall, think + look like columns) 4) Transitional (change their shape from cuboidal to squamous as they are stretched e.g. found in bladder) Epithelial tissues can be arranged in 2 ways: 1) Simple (single layer of cells) 2) Stratified (many cells stacked on top of one another Ma Pseudostratified = appears to have many layers glan but only has one layer - Epithelial tissues are unique because they don't have a blood supply (no blood vessels present) - Substances diffuse from blood vessels in the underlying connective tissue to nourish these cells e.g. the respiratory, digestive and Genito-urinary systems are all lined with epithelial tissue e.g. Skin (type of epithelial tissue) covers the outside of the body 2) CONNECTIVE TISSUE Joins or glues tissues together - In many organs connective tissue glues epithelial and muscle tissue together - Most common tissue found in the body - Diverse tissue (consistency ranges from a fluid to a solid) 5 different types of connective tissue found in the human body: 1) Blood/lymph (found in blood and lymph vessels) 2) Cartilage (found in the ends of bone e.g. in ears + septum of the nose) 3) Dense connective tissue (attached to bones + muscles) (a) Ligaments (b) Tendons in + inside of the outh ammary + salivary nds  2) Cartilage (found in the ends of bone e.g. in ears + septum of the nose) 3) Dense connective tissue (attached to bones + muscles) (a) Ligaments (b) Tendons 4) Loose connective tissue (wrapped around organs as a protective layer) a) Fat b) Areolar 5) Bone 3) MUSCLE TISSUE Provides the means for movement of the body + substances within it - Classified according to its ability to contract voluntarily + the presence of striations (stripes) in the muscle cells 3 types of muscle tissue: Skeletal = found in the muscles attached to the skeleton - Contract voluntarily - contain striations Cardiac = found in the heart - Contract involuntarily - Contain striations Smooth = found in internal organs + blood vessels - Contract involuntarily 4) NERVOUS TISSUE A rapid messenger system, delivering messages from one part of the body to another part very quickly. There are 2 categories of nerve cells found in nervous tissue: The basic messaging unit of nervous tissue is a cell = neuron (receives/transmits electrical impulses over a distance) a) Contains a cell body b) Contains dendrites (cell extensions) c) Contains axons (receive + send information from one nerve cell to another) i. Axons are covered by the myelin sheath (acts as insulation + speeds up the rate of nerve impulse transmission) Number of different types of support cells = glia (cells provide metabolic support for the  from one nerve cell to another) i. Axons are covered by the myelin sheath (acts as insulation + speeds up the rate of nerve impulse transmission) Number of different types of support cells = glia (cells provide metabolic support for the neurons) At the centre of the cardiovascular system = the heart that pumps blood to the lungs to pick up oxygen and to body tissues to deliver oxygen. - The blood vessels that carry blood also transport nutrients and chemical messages (in the form of hormones) to tissue cells and waste to the kidneys and lungs for excretion. - It is vital that these substances are delivered to their destination in a timely manner ANATOMY + PHYSIOLOGY COMPONENTS OF THE CARDIOVASCULAR SYSTEM (ANATOMY) Cardiovascular system is a multi-organ body system with 3 major components (work together to ensure that chemical substances are transported around the body in an efficient manner): 1) HEART - organ that pumps blood through the system 2) BLOOD VESSELS - network of passages that transport the blood to and from the body's cells 3) BLOOD - a form of connective tissue that has a fluid component called plasma and a variety of cells + substances FUNCTION OF THE CARDIOVASCULAR SYSTEM (PHYSIOLOGY) The cardiovascular system has 4 essential functions: Pumps materials throughout the body Transports blood throughout the body Delivers important substances like nutrients and oxygen gas to body cells and removes (PHYSIOLOGY) The cardiovascular system has 4 essential functions: Pumps materials throughout the body Transports blood throughout the body Delivers important substances like nutrients and oxygen gas to body cells and removes metabolic waste Returns excess tissue fluid back to the bloodstream THE HEART - Approximately the size of a fist - Contains a series of chambers through which circulating blood passes HEART WALL The heart is surrounded by a serous membrane (reduces friction on organs with body cavities) = pericardium - Outer layer of membrane is tough + fibrous Under the serous pericardium comprises a parietal layer next to the fibrous heart covering and a visceral layer that is fused to the heart surface. - Between the two layers = pericardial cavity The walls of the heart also contain numerous layers The outer layer of the heart wall = epicardium The middle layer of the heart wall = made of heart muscle called myocardium The heart is lined by epithelium = endocardium HEART CHAMBERS The heart is located in the thoracic cavity. - The base of the heart is proximal to the head while the apex is distal - The heart may also be divided into right and left sides which act as separate pumps The heart has 4 separate chambers (two on each side). Each side of the heart has a chamber that receives blood and another that discharges it. The atria (receive blood and move it to the ventricles) are receiving chambers. Located at the top of the heart The ventricles (must contract and send blood over a distance to other parts of the body) are discharging chambers. Located at the bottom of the heart. - Atria are smaller than the ventricles + the  the top of the heart The ventricles (must contract and send blood over a distance to other parts of the body) are discharging chambers. Located at the bottom of the heart. - Atria are smaller than the ventricles + the walls are thinner BLOOD VESSELS (transport system of the cardiovascular system) The blood vessels form a continuous network of tubes that transport blood away from and back towards the heart (continuous loop) ARTERIES = large, elastic blood vessels that take blood AWAY from the heart to body tissues. - As the blood moves away from the heart, these arteries branch becoming smaller arterioles CAPILLARIES = when the transport network reaches important tissues, these very small vessels (found in tissue beds) are the site of transfer for materials in and out of the blood - As the blood returns to the heart the capillaries merge together into larger vessels called venules which then become larger vessels called VEINS which return blood back to the heart ARTERIES VEINS - Large vessels - Large - Arteries take blood away from the heart - Veins - Arteries carry blood under pressure, so their walls are thicker than veins - Walls e.g. tunica media is thicker e.g. the lum ARTERIES CONNECTED TO THE HEART VEINS CON 2 main arteries that take blood away from the heart: - Blood 1) Aorta = takes blood that is rich in oxygen from the left ventricle of the ATRIU heart to the body and systemic circulation - Oxyg 2) Pulmonary artery (only arteries in the body that transport deoxygenated ATRIU blood)= takes blood that is low in oxygen from the right ventricle to the lungs where gas exchange occurs e vessels s return blood to the heart s are less thick than arteries men (space inside) is smaller in arteries NNECTED TO THE HEART d from the body that is low in oxygen enters the RIGHT UM of the heart via the superior and inferior vena cava gen rich blood coming from the lungs enters the LEFT UM via the pulmonary veins HEART VALVES As the heart pumps, blood is moving through the different heart chambers. So that the pumping works efficiently, heart valves ensure that blood flows in only one direction to prevent backflow. There are 4 valves in total (two for each side): 1) ATRIOVENTRICULAR VALVES (AV valves) = located between atria and ventricles 2) BICUPSID/MITRAL VALVE = separates the atrium + ventricle on the left side of the heart - Has two flaps 3) TRICUPSID VALVE = separates the atrium + ventricle on the right side of the heart - Has three flaps 4) SEMILUNAR VALVES (SL valves) = located between a ventricle + an artery (exit points  - Has two flaps 3) TRICUPSID VALVE = separates the atrium + ventricle on the right side of the heart - Has three flaps 4) SEMILUNAR VALVES (SL valves) = located between a ventricle + an artery (exit points where blood leaves the heart) - On the right side of the heart, blood leaves the right ventricle via the pulmonary SL valve (blood passes into the pulmonary artery to travel to the lungs) - On the left side of the heart, blood leaves the left ventricle via the aortic SL valve (blood passes into the aorta to travel to the body) THE CARDIAC CYCLE Comprises the events of one complete heartbeat. 2 phases defined by what is happening to the ventricles (both sides of the heart undergo the same events at the same time) - When the lower chambers are contracting = systole/systolic phase (Blood is forced out of the heart) - When the lower chambers are relaxed = diastole/diastolic phase (blood fills the heart) HEART RATE = the number of heart beats (cardiac cycles) per minute At the beginning of the cardiac cycle, both the atria + ventricles are relaxed (in diastole). - Blood flows into the right atrium from the superior and inferior venae cavae and the coronary sinus. - Blood flows into the left atrium from the 4 pulmonary veins. - The right + left AV valves are open (blood is able to pass from the atria into the ventricles) - The two semilunar valves are closed Next, the left + right atria contract, pressure rises and blood is forced into the ventricles as the atria empties. - As the ventricles continue to fill, they contract closing the AV valves - Strong contraction at the base of the ventricles causes the SL valves to open and blood is ejected from the heart. This completes the cycle and the heart is again relaxed  closing the AV valves - Strong contraction at the base of the ventricles causes the SL valves to open and blood is ejected from the heart. This completes the cycle and the heart is again relaxed CIRCULATION - The heart acts a double pump with each side pumping blood at the same time to 2 different locations. In systemic circulation (circulation to body tissues), the blood is circulated from heart to body to heart. Oxygen rich blood leaves the heart from the left ventricle, circulates around the body and returns to the right atrium of the heart with a low oxygen concentration. In pulmonary circulation (circulation to the lungs), the blood is circulated from heart to lungs to heart. Oxygen depleted blood leaves the heart from the right ventricle, circulates to the lungs where gas exchange occurs and returns to the left atrium with a high oxygen concentration. PULMONARY CIRCULATION Pulmonary circulation takes oxygen depleted blood from the heart to the lungs to receive more oxygen. - Blood enters the right atrium via the superior vena cava. VENA CAVAE = veins that return blood (low in oxygen gas) to the heart from the body - Blood enters the right atrium, passes through the tricuspid valve and enters the right ventricle. - When the ventricle contracts the blood is forced through the pulmonary SL valve where the blood enters the pulmonary arteries and goes to the lungs. In the lungs the blood picks up oxygen gas before being returned to the heart to enter systemic circulation. - Blood (rich in oxygen gas) enters the left atrium via the pulmonary veins - After entering the left atrium, the blood passes through the bicuspid valve and enters being returned to the heart to enter systemic circulation. - Blood (rich in oxygen gas) enters the left atrium via the pulmonary veins - After entering the left atrium, the blood passes through the bicuspid valve and enters the left ventricle. This ends the pulmonary circuit SYSTEMIC CIRCULATION Takes oxygen rich blood from the heart to the body tissues to pass the oxygen to cells. - When the left ventricle contracts, the blood is forced through the aortic SL valve where the blood enters the aorta for circulation around the body - Once the blood has circled the body it returns (depleted of oxygen) back to the heart for the process to be repeated CORONARY CIRCULATION The heart pumps blood to the lungs and body but heart muscle also requires a rich supply of blood for optimal functioning. Coronary blood vessels supply the heart muscle with oxygenated blood. - Cardiac cells require oxygen to function. Oxygen rich blood is diverted from the aorta to the left and right coronary arteries (branch into smaller branches - heart muscle gets a consistent supply of oxygen rich blood) - The coronary veins return the oxygen depleted blood back to the heart via the coronary sinus. - The blood will re-enter pulmonary circulation and be sent to the lungs to pick up more oxygen Blockage of coronary vessels can lead to serious health implications FOETAL CIRCULATION A pre-term foetus doesn't have fully developed lungs, access to oxygen gas in the outside word and blood vessels that service the lungs. - As a result more blood bypasses the pulmonary circuit and the foetus relies on the mother's bloodstream to obtain vitally important oxygen gas and nutrients + to remove waste blood vessels that service the lungs. - As a result more blood bypasses the pulmonary circuit and the foetus relies on the mother's bloodstream to obtain vitally important oxygen gas and nutrients + to remove waste - Nutrient + gas exchange occurs through the placenta. Two shunts ensure blood supply bypasses the underdeveloped foetal lungs: foramen ovale that connects the two atria ductus arteriosus connecting the aorta and pulmonary trunk. These structures close at birth when the newborn takes its first breaths THE INTRINSIC CONDUCTION SYSTEM (ICC) THE ICC is an example of electricity in the body. Skeletal muscles in the human body contract in response to nervous impulses. - ICC is not made of nerve tissue, but specialised heart/cardiac cells that contract spontaneously The function of the ICC is to maintain regular beating of the heart (auto rhythmicity). - coordinates the contraction of atria + ventricles so the pumps don’t malfunction Components of the system: Sinoatrial node (SA node) A collection of pacemaker cells located at the top of the right atrium. Atrioventricular node (AV node) Second collection of pacemaker cells. Atrioventricular bundle (AV bundle/bundle of His) Right and left bundle branches Purkinje fibres PACEMAKER CELLS = send out an electrical stimulus that regulates the contraction of heart muscle (set the pace) ○ During the cardiac cycle the SA node fires an electrical stimulus across the walls of both atria causing them to contract (sets the pace at which the heart beats). ○ This impulse is carried, in one direction, into the AV node where there is a short delay  ○ During the cardiac cycle the SA node fires an electrical stimulus across the walls of both atria causing them to contract (sets the pace at which the heart beats). ○ This impulse is carried, in one direction, into the AV node where there is a short delay before the impulse passes via the AV bundle and right and left bundle branches to the apex of the heart ○ The Purkinje fibres distribute the impulse to contractile cells in the ventricles causing them to contract (contractions results in a heartbeat) This sequence of events may be measured with an electrocardiograph HEART MEASUREMENT - ELECTROCARDIOGRAM (ECG) An ECG is an instrument for measuring electrical activity of the heart. - Electrodes are placed at specific locations on the chest of the patient and a ECG is generated. This output can be used to study the electrical activity of the heart to detect any abnormalities. A normal ECG has 3 distinct components/waves that correspond to events in the cardiac cycle: P WAVE = first wave on the ECG and corresponds to the contraction of the atria (represents the electrical signal/impulse generated by the SA node prior to the atrial contraction) QRS COMPLEX = corresponds to the contraction of the ventricles which begin to contract at the peak (wave is large because the ventricles of the heart are larger than the atria) T WAVE = represents the ventricle at rest awaiting the next contraction (the repolarisation of the atria is not visible on an ECG because it lies under the much larger QRS complex) Specific measurement e.g. height, length + depth of each component are used to determine cardiac performance. Abnormal waves may result due to cardiac arrythmias.  complex) Specific measurement e.g. height, length + depth of each component are used to determine cardiac performance. Abnormal waves may result due to cardiac arrythmias. CARDIOVASCULAR DISEASE Diseases of the cardiovascular system can have serious health consequences as the efficient pumping of the heart is necessary to provide the body with oxygen + nutrients (necessary for life). It also transports metabolic waste for elimination from the body. - Brief disruption of this vital function may lead to death Disease may involve mechanical or electrical issues with the heart or blockages of the vessels that transport the vital blood to the lungs and body tissues. HEART DISEASE MECHANICAL ELECTRICAL Myocardial infarction (heart attack) occurs when the heart muscle is Problems of an electric starved of oxygen. This occurs when blood vessels that supply in abnormal heart rhyt blood to the heart become blocked. e.g. bradycardia, sick s - Cardiac muscle cells can be irreversibly damaged and lead to long term mechanical problems Infection of the heart muscle may also lead to irreversible damage to the heart = cardiomyopathy. In both cases heart transplant may become necessary for long term survival as cardiac muscle cannot repair itself. VASCULAR DISEASE Atherosclerosis = disease of the blood vessels - hardening of the arteries (common to all of us as we age) CAUSE = thickening of the inner layer of blood vessels (reduces flexibility and results in brittleness which can increase their tendency to rupture - resulting in an elevation of blood pressure of hypertension). - Healthy vessels have a smooth interior allowing blood to pass freely through the network with minimal resistance. - In atherosclerosis, fatty deposits of plaque accumulate on the inside of the vessels and  cal nature lead to conduction defects. These can result thms. sinus syndrome and atrioventricular block hypertension). - Healthy vessels have a smooth interior allowing blood to pass freely through the network with minimal resistance. - In atherosclerosis, fatty deposits of plaque accumulate on the inside of the vessels and impede blood flow increasing the peripheral resistance (vessels can become blocked) TREATMENT = angioplasty to open the lumen of the vessel Insertion of stents to mechanically hold the affected vessel open