Compendium 6 Flashcards
Main functions of the cardiovascular system
Transports fluids, wastes, gases, hormones around the body
Exchange of materials between blood, cells and extracellular fluid
Plays role in immune response, blood pressure, regulation body temperature
What makes up the cardiovascular system
Heart
Blood vessels
Capillary beds
Blood
What are the functions of the heart
Generate blood pressure through contractions
Routes blood through either systemic or pulmonary circulation
Ensures one way blood flow
Regulates blood supply to match body’s needs
“2 pumps in 1”
-right side receives blood coming from body (low O2) and pumps through right side into pulmonary circulation towards lungs
- left side received oxygenated blood from lungs, pumped through left side to systemic circulation around body
Where is the heart located
Located in thoracic cavity in mediastinum between lungs
Apex= most inferior part
Base= flat part with major blood vessels
Lies slightly obliquely, with apex towards left
2/3 heart lie on left side of midline, which makes left lung smaller than right
Transverse width heart ~ 132mm, transverse width chest ~224mm
Explain the pericardium of the heart
Tough, fibrous outer layer that prevents overstretching and overfilling and anchors heart into mediastinum
Serous: thin, transparent, inner layer made of simple squamous epithelium (smooth to allow good flow)
- parietal: lines outer fibrous layer
- visceral: covers whole heart
- fluid in pericardial cavity
Explain the walls of the heart
Surrounds each chamber (2 ventricles, 2 atria)
Consist of 3 tissue layers:
1) epicardium: serous membrane, smooth outer surface
2) myocardium: middle layer composed of cardiac muscle cells for contractibility (thickest layer)
3) endocardium: smooth, inner surface of chambers in contact with blood in heart
Also muscles that increase movement and turbulence of blood flow:
Pectinate: muscular ridges and columns on inside walls of atria
Trabeculae: muscular ridges and columns on side walls on ventricles
Explain the atria of the heart
Superior
Thinner than ventricles
Right atrium:
-3 major openings receiving deoxygenated blood from body: superior vena cava (top half body), inferior vena cava (bottom half body) and coronary sinus (blood from heart itself)
Left atrium:
-four openings receiving oxygenated blood: left and right pulmonary veins (2 on either side of the heart)
Explain ventricles of the heart
Inferior
Atrioventricular canals= openings between atria and respective ventricles
-contain atrioventricular valves
Wall of left ventricle thicker as does most contractions with high pressure in order to pump blood through whole systemic circulation
RV opens to pulmonary trunk and contains trabeculae corneae muscles on inside to increase turbulence and blood flow
LV opens to aorta, is very muscular wall
Interventricular septum is between the two ventricles
Explain greater vessels of the heart
Blood flow:
Superior and inferior vena cava –> right atrium
Right ventricle exits through PULMONARY TRUNK which branches into left and right pulmonary arteries
From lungs goes through left and right PULMONARY VEIN to left atrium
Once in left ventricle exits via AORTA into systemic circulation
Explain atrioventricular valves of the heart
Ensure blood flows in one direction and helps generate pressure
Between atrium and ventricles there are valves which have leaf-like cusps attached to papillary muscles by strong fibrous tendons called chordae tendineae – allow 1 way flow as when muscles contract, it pulls on tendons and prevents valves opening into atria and therefore prevents backflow
Left atrioventricular/bicuspid/mitral valve has 2 cusps
Right atrioventricular/tricuspid valve has 3 cusps
Blood flows when valve opens from atrium to ventricles
Explain how the cusps of valves work in the heart
Cusps filled = valve closed = no backflow
Ventricle fills up which generates greater pressure so greater blood flow through systemic circulation
Cusps empty = valve open = blood exits heart
Explain aortic and semilunar valves of the heart
Pulmonary semilunar valves found at base of pulmonary trunk
Aortic semilunar valve found in aorta
Explain arteries
Elastic, muscular Arterioles =smallest type Carry blood AWAY from heart Contain blood under pressure Two major arteries leaving heart are pulmonary trunk from right ventricle and aorta from left ventricle
Explain capillaries
Site of exchange with tissues
Smallest, most request blood vessel
Form capillary beds
Explain veins
Take blood to heart
Thinner walls than arteries, contain less elastic tissue, less smooth muscle
Contain valves to prevent backflow
Venules = smallest type, veins get bigger as they go towards the heart
Two major veins entering heart are superior and inferior vena cava into right atrium and pulmonary veins into left atrium
Describe walls of veins and arteries
TUNICA INTIMA: endothelium (touches blood)
TUNICA MEDIA: smooth muscle cells involved in vasoconstriction and vasodilation
TUNICA EXTERNAL/ADVENTITIA: connective tissue, goes from dense and becomes looser when it move further from media layer and towards surrounding vessels so they can merge
Explain walls of capillaries
Walls contain simple squamous endothelial cells, basement membrane, delicate connective tissue layer (not all have this)
List functions of blood
Transport wastes, gases, nutrients, process molecules, hormones, enzymes Regulation pH and osmosis (~7.4) Maintenance body temp Protection against foreign substances Clot formation
Explain composition of blood
Connective tissue
Formed elements: platelets, white blood cells, red blood cells
Plasma: proteins, water, other solutes
Platelets needed for blood clotting and sealing holes in blood vessels
Describe red blood cells
No nucleus
Bi-concave shape to increase SA and O2 carrying capacity
Do not live for long
Explain pulmonary circulation
Deoxygenated blood enters right atrium and moves to right ventricle then exits ventricle through pulmonary trunk to either left or right pulmonary artery then to left or right lung where gas exchange occurs
Deposit CO2, obtains O2
O2 goes from high conc in lungs to low conc. in blood
Oxygenated blood then flows through left or right pulmonary vein to left atrium
Explain systemic circulation
Oxygenated blood enters left atrium and flows through bicuspid valve to left ventricle which contracts and pushes blood out of heart via aorta which branches into ascending aorta, aortic arch and descending aorta
Blood is then delivered to all cells and tissue in body for gas/nutrient/fluid exchange
Blood exits capillary beds and moves towards veins travelling back to heart and re enters right atrium through vena cava
List the blood flow through the heart
1) deoxygenated blood enters right atrium via superior or inferior vena cabs
2) flows through tricuspid valve into right ventricle
3) as right ventricle contracts, blood flows through pulmonary semi lunar valve into pulmonary trunk
4) trunk divides into left and right pulmonary arteries to travel to lungs
5) oxygenated blood re enters left and right pulmonary veins and travels to left atrium
6) flows through bicuspid valve to left ventricle
7) left ventricle contracts moving blood through aortic semilunar valve in aorta and then exits to body
How does the heart get its own blood supply
Blood would continue from aorta to coronary arteries which travel to heart tissue
Blood is now is coronary circulation
Travels through coronary sinus and cardiac veins then towards right atrium
What forces the movement of blood through the circulatory system
Moves from areas of high pressure to areas of low pressure
What is the cardiac cycle
Repetitive contraction (systole) and relaxation (diastole) of heart chambers moving blood through the heart and body
Relax=fill up, contract=pump
What is cardiac output
The amount of blood leaving the heart each minute
CO= HR x SV
HR= number of beats per minute SV= amount of blood pushed out of heart with each contraction (usually around 70mls/beat)
How do you calculate the % increase of cardiac output after exercise
Increase CO in L/min divide CO at rest in L/min x 100
What is pulse
Pressure caused by the ejection of blood from left ventricle which travels along arteries in body to create pulse points
Pulse points- facial, neck, near elbow, wrist, underarm, very top inner thigh, near ankles
Pulse points cause when large arteries are closer to the skin or close to/on top of a bone
How can other parts of the body control the cardiovascular system
Nervous system- maintains blood pressure and flow through cardiac centre
Hormonal- adrenaline increase heart rate, vasoconstriction, stroke volume in response to stress or exercise
Explain how the heart beats itself
Heart generated own action potential to contract
1) action potential in sinoatrial node
2) spreads across atrium towards atrioventricular node
3) passes through AV node and AV bundle
4) passes fibrous skeleton towards interventricular septum
5) each AV bundle divides into left and right branches so continues to travel down heart and then towards side of heart to reach purkinjie fibres (conducting cells of heart located in wall)
6) now ventricles told to contract
Heart diseases
Arrhythmia: heart skips beats, require medical attention
Cardiomyopathy: heart muscle gradually weakens, need to adopt lifestyle changes
Coronary heart disease: coronary arteries become clogged and narrow over time, needs medical attention
