UNIT 5 - CARDIOVASCULAR SYSTEM : HEART AND BLOOD VESSELS Flashcards
what is included in the cardiovascular system?
-heart
-blood vessels
what is the function of the cardiovascular system?
-TRANSPORT (oxygen, carbon dioxide, other waste products, nutrients, and hormones)
-PROTECTION (immune cells are transported to prevent infection)
-REGULATION (maintains homeostasis of different body conditions, ex: pH + electrolyte levels)
what system assists the cardiovascular system? how does it do so?
-lymphatic system
-collects excess tissue fluid and returns it to the blood (lymph when enters the lymphatic vessels)
what are the types of blood vessels?
-arteries
-arterioles
-veins
-venules
-capillaries
where do arteries carry blood?
-away from the heart
what are the 3 layers of the artery walls?
-endothelium (thin inner epithelium)
-middle layer (smooth muscle +elastic tissue)
-outer layer (CT)
how do the different aspects of the middle layer of the artery walls provide function?
-smooth muscle (allows arteries to expand)
-elastic tissue (allows arteries to recoil)
what are arterioles?
-small arteries
how does the smooth muscle layer of the arteries and arterioles affect blood flow and pressure?
-contracts to constrict the vessel (reduce blood flow, increase blood pressure)
-relaxes to dilate the vessel (increase blood flow, reduce blood pressure)
where are the capillaries located?
-between arterioles and venules
what are the characteristics of capillaries?
-microscopic vessels
-form capillary beds
-have precapillary sphincters
-only have an endothelium layer
what occurs at the capillary beds
-gas, nutrient, and waste exchange
what is the purpose of the precapillary sphincters? what happens if they close?
-control blood flow through the capillary bed
-when closed the blood flows through an arteriovenous shunt to bypass the capillaries
what are venules?
-smaller veins that receive blood from the capillaries
where do veins carry blood?
-towards the heart
what are the layers of vein and venule walls?
-same 3 layers as arteries
-less smooth muscle in the middle layer (thinner walls to hold more blood)
how much of the blood are held in the veins?
-70%
how do veins carry blood against gravity?
-contain valves
what happens if blood is lost? (hemorrhage)
-nervous system causes some veins to constrict in order to increase blood volume available to the main organs
-causes skin to become pale (constriction)
what are the characteristics of the heart?
-located between the lungs
-tip (apex) points toward the left hip
-consists mainly of myocardium (cardiac muscle tissue)
-double pump
-divided internally by the septum (left/right)
what are the characteristics of cardiac muscle fibres?
-branched
-connected by intercalated discs (contain gap junctions)
-connected by desmosomes (prevents overstretching)
how is the heart a double pump?
-right side pumps blood toward the lungs
-left side pumps blood toward the rest of the body
what surrounds the heart?
-a sac called the pericardium
-secretes pericardial fluid for lubrication
what are the 4 chambers of the heart?
-2 upper atria
-2 lower ventricles
what are the 2 types of valves in the heart?
-atrioventricular valves (AV)
-semilunar valves
what are the 2 atrioventricular valves?
-tricuspid valve (right)
-bicuspid/mitral valve (left)
what reinforces the atrioventricular valves?
-chordae tendineae
what are the 2 semilunar valves?
-pulmonary valve
-aortic valve
what are the parts of coronary circulation?
-coronary arteries (supply blood to the heart, first branches off the aorta)
-coronary veins (drain blood from the heart, empty into right atrium)
what is coronary artery disease?
-blockage in the coronary artery
-causes a heart attack (myocardial infarction)
-circulation is decreased (less oxygen going to the heart)
how does blood flow through the right side of the heart?
-superior and inferior vena cava carry O2 poor and CO2 rich blood from the body to the right atrium
-blood flows through the tricuspid valve into the right ventricle
-right ventricle pumps blood through the pulmonary valve into the pulmonary trunk (branches to the left/right pulmonary arteries)
how does flood flow through the left side of the heart?
-pulmonary veins carry O2 rich and CO2 poor blood from the lungs to the left atrium
-blood flows through the bicuspid valve into the left ventricle
-left ventricle pumps blood through the aortic valve into the aorta (goes into smaller arteries)
what is special about the walls of the left ventricle compared to the right ventricle?
-left ventricle walls are thicker since it must pump blood to the entire body
-right ventricle only pumps blood to the lungs
are the walls of the atria or ventricles thicker?
-ventricles (pushing against gravity)
what is the cardiac cycle?
-atria first contract together
-ventricles then contract together
-heart then relaxes
what are the 2 parts of the cardiac cycle? when do they occur?
-systole (contraction) (pumping)
-diastole (relaxation) (filling)
what are the 2 sounds of the heart? when do they occur?
-lub (closure of AV valves)
-dub (closure of the semilunar valves)
how many times does the cardiac cycle occur per minute?
-70 times
what is a heart murmur?
-swishing sound between lub + dub
-regurgitation of blood (valves don’t close properly)
what is the internal conduction system?
-nodal cells send signals spontaneously
what are the 2 nodes within the heart? which chamber are they in?
-sinoatrial node
-atrioventricular node
-both in the right atrium
what signal does the sinoatrial node send?
-initiates each heartbeat
-causes the atria to contract
-pacemaker of the heart
what signal does the atrioventricular node send?
-sends a signal to the AV bundle of his and purkinje fibres
-causes the ventricles to contract
what do the signals sent by the nodes travel through?
-gap junctions in the intercalated discs
what is the external control of heartbeat?
-cardiac control center in the brain increases or decreases heartbeat depending on the bodies needs
-increase = sympathetic nervous system (fight or flight)
-decrease = parasympathetic nervous system (relaxation)
what is an example of a hormone that increases heart rate?
-adrenaline
what is an example of a neurotransmitter that decreases heart rate?
-acetylcholine
what is an ECG/EKG?
-recording of the electrical changes in the heart muscle during a cardiac cycle
what are the different aspects shown on an EKG?
-P wave (atria produce an electrical current when stimulated by the SA node)
-QRS complex (electrical current travelling through the ventricles, signals that the ventricles are about to contract)
-T wave (recovery of the ventricles)
what does an EKG detect?
-abnormalities within the electrical signals of the heart
what is ventricular fibrillation?
-uncoordinated rhythm of electrical signals in the ventricles
-heart cannot pump properly (tissues become starved of oxygen)
how does ventricular fibrillation get solved?
-defibrillation
-apply a strong electrical signal to reset the heart (SA node will begin to fire)
what is blood pressure? how is it measured?
-pressure that blood exerts against the blood vessel wall
-created by the contraction of ventricles (propels blood into the arteries)
-measured with a sphygmomanometer (in the brachial artery)
where is the blood pressure highest?
-in the aorta
-decreases as it flows through the bodies vessels
-very low in veins (does not contribute much to movement of blood)
what is a pulse?
-surge of blood into an artery
-causes the walls to stretch and then recoil
-measurement of heart rate
where can you best detect a persons pulse?
-radial artery
-carotid artery
-60/80 per minute
what is systolic pressure?
-the highest pressure when blood is ejected from the heart
what is diastolic pressure?
-the lowest pressure when the ventricles relax
what is the average blood pressure?
120/80 mmHg (systolic/diastolic)
what is hypertension?
-high blood pressure
-140 systolic or 90 diastolic (or greater)
-silent killer because few symptoms until a heart attack, stroke, or kidney failure occurs
what is hypotension?
low blood pressure
why is it key that blood flow is slowest in the capillaries?
-to increase gas, nutrient, and waste exchange
what adjusts blood flow?
-precapillary sphincters
what can decrease blood pressure?
-drugs that dilate the arterioles
what are the 3 factors that venous return depends on?
-skeletal muscle pump
-respiratory pump
-valves
how does the skeletal muscle pump work together with valves in the veins?
-skeletal muscle contracts and pushes blood to open the valve
how does the respiratory pump work in the veins?
-dependent on breathing (diaphragm movement)
what is the pulmonary circuit?
-circulates blood through the lungs
what is the systemic circuit?
-circulates blood through the body tissues
what is the pathway of the pulmonary circuit?
-right atrium pumps deoxygenated blood to the right ventricle which then pumps it to the pulmonary trunk
-pulmonary trunk splits into right and left pulmonary arteries which go to the lungs (gas exchange in capillaries)
-4 pulmonary veins empty into the left atrium (carrying oxygenated blood)
what is the pathway of the systemic circuit?
-left ventricle pumps oxygenated blood into the aorta which branches to all the tissues of the body
-veins eventually lead to the superior and inferior vena cavae
-the vena cavae empties deoxygenated blood into the right atrium
what is a special route that does not follow the typical systemic circuit?
-hepatic portal system
what is the hepatic portal system?
-deoxygenated but nutrient rich blood flows from the digestive system into the hepatic portal vein to the liver
-the liver synthesizes blood proteins from amino acids brought by the hepatic portal vein and stores glucose as glycogen
-the liver also removes toxins and pathogens that enter the blood through the digestive system
-blood is drained from the liver into the hepatic veins which drain into the inferior vena cava
what are the two forces that drive fluid in and out of the capillaries?
-blood pressure (out @ arteriole end)
-osmotic pressure (in @ venule end)
what fluid is leaving capillaries? where does some of this fluid go?
-contains everything that blood contains except cells and plasma proteins
-into the lymphatic system
what are disorders of the blood vessels? what do these often lead to?
-hypertension and atherosclerosis
-often lead to a stroke, heart attack, or aneurysm
how is hypertension treated?
-diuretics that increase urine production
-other drugs
what is atherosclerosis?
-a buildup of atherosclerotic plaque in the walls of blood vessels
-plaque narrows blood vessel diameter (decreasing tissue blood supply)
-can cause clots to form in the walls of arteries
what are the 2 types of clots?
-thrombus (stationary clot)
-embolus (clot that detaches and moves to distant sites)
what is a thromboembolism?
-an embolus that becomes lodged in a blood vessel
when and why does a stroke occur? what are the symptoms?
-when a cranial artery is blocked or bursts
-part of the brain dies due to a lack of oxygen
-numbness of hands/face, difficulty speaking, inability to see in one eye
when and why does a heart attack occur? what can it begin with?
-blocked coronary artery
-part of the heart dies due to a lack of oxygen
-can begin with angina pectoris
what is angina pectoris?
-partially blocked coronary artery
-causes chest pain
-treated with drugs that dilate blood vessels
what are 3 ways you can treat a clogged artery?
-angioplasty
-gene therapy
-coronary bypass operation
what is an angioplasty?
-insert a tube into the clogged artery with a stent (mesh cylinder to hold it open)
-stents are usually coated in drugs to dissolve blockages
-also typically contains a balloon to expand the stent
what is gene therapy?
-injection of the gene for vascular endothelial growth factor to induce growth of new vessels
-will not need a bypass surgery
what is a coronary bypass operation?
-a vein from the leg is taken and used to bypass a clogged artery
what is an aneurysm?
-ballooning of a blood vessel
-typically the abdominal aorta or blood vessels in the brain
-atherosclerosis or hypertension can weaken a vessel and cause ballooning
-if major artery ruptures, death can result
what are ways to treat heart failure?
-wrapping the heart (prevent enlargement)
-implant a cardioverter-defibrillator (corrects irregular rhythm)
-heart transplant
-injection of stem cells (repair)
-battery powered pump to assist the heart
-total artificial heart (temporary)
