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level: 6.2 The Blood Sytem

Questions and Answers List

level questions: 6.2 The Blood Sytem

QuestionAnswer
What is the role of a pacemaker?it causes the cardiac cells to act in unison to cause a sinus rhythm
What are the functions of the cardiovascular system?(3)circulates important materials such as oxygen, nutrients and water removes waste products maintains a constant body temp and transports hormones
What are the components of the cardiovascular system? (3)blood = fluid medium where materials are transported vessels = functions as a network which move blood through Heart = acts as a pump to drive the movement of blood through the vessels
Who discovered the circulatory system?William Harvey
What did William Harvey find out about the circulatory system? (3)major vessels (Arteries and veins) are part of a single, connected network The heart works as a central pump (arteries = away from heart ; veins = return to heart) Blood flow is continuous (not consumed) and unidirectional (with valves)
Draw a basic labelled heart (5)2 atria and 2 ventricles
why does the left side have a thicker muscular wall?myocardium = has to pump blood further than the right side as it contains oxygenated blood
What does the left and right side of the heart do?left side: oxygenated blood around the body (systemic circulation) = thicker muscular wall (myocardium) as it has to pump blood further than the right side Right side: deoxygenated blood to the lungs (pulmonary circulation)
What are ventricles in the heart? (3)pumps, remove blood from the heart at high pressures from the arteries left ventricle = bicuspid valve + aortic valve right ventricle = tricuspid valve + pulmonary valve
What is the atria (atrium) in the heart? (3)reservoirs, blood returning to the heart is collected in veins and passed onto ventricles left atrium = bicuspid and aortic valve right atrium = tricuspid and pulmonary valve
What are the 4 valves in the heart?Atrioventricular valves (between atria and ventricles) – bicuspid valve on left side ; tricuspid valve on right side Semilunar valves (between ventricles and arteries) – aortic valve on left side ; pulmonary valve on right side
What are the names of the veins and arteries attached to the heart? Which part of the heart are they attached to? (5)vena cava (inferior and superior) = right atrium and returns deoxygenated blood pulmonary artery connects to the right ventricle to send deoxygenated blood to the lungs pulmonary veins goes into the left atrium with oxygenated blood from the lungs aorta goes from the left ventricle to send oxygenated blood around the body veins = atriums artery = ventricles
What do vessels do?transport blood in the cardiovascular system
What are the 3 different types of blood vessels?Arteries = transports blood from heart at high pressure (thick walls) Capillaries = exchanges material bw blood and tissue (single endothelial layer) SMALLEST Veins = transports blood back to heart at low pressure (thin walls)
How are the vessels connected? (4)Arteries branch into arterioles which form capillaries = decreases pressure as the total volume increases the branching into capillaries makes sure blood is moving slowly capillaries is the smallest vessels and connects the arteries and the veins capillaries pool into venules which becomes veins
What is the function of the arteries?moves blood at high pressure from the ventricles to the body
How are arteries specialized? (4)narrow lumen compared to the wall thickness - high blood pressure thick wall with outer layer of collagen = stops artery from rupturing from high pressure inner layer of muscle + elastic fibres = maintains pulse flow don't have valves bec backflow isn't possible with high pressures
How would you describe the way blood flows through the arteries?repeated, rhythmic surges = pulses
How do the arteries maintain a high blood pressure between pump cycles?with the muscle and elastic fibers
How do muscle fibres help maintain a high blood pressure in arteries? (3)rigid arterial wall for high blood pressure without rupturing to narrow the lumen = increase pressure bw pumps maintains blood pressure throughout cycle
How do elastic fibres help maintain a high blood pressure in arteries? (3)arterial wall stretches and expands with pulse flow through lumen = pressure releases on arterial wall is returned to blood when artery becomes normal size again (elastic recoil) = pushes blood forwards + maintains pressure
What do capillaries do?material exchange between blood and tissues
How are capillaries specialized? (3)very small lumen = only a single red blood cell at a time transports blood at low pressure = maximizes material exchange walls are a single endothelial cell layer, surrounded with a basement membrane = minimizes diffusion distance and is permeable extensive
How are capillary walls different in different locations? (3)continuous w endothelial cells, held together with tight junctions = limits absorption of large molecules Absorption tissues (kidneys, intestine) = fenestrated (many pores) permeable to large molecules (in liver) = sinusoidal , open spaces between cells
What materials enter and exit blood in capillaries? (4)materials that exit blood = nutrients and oxygen (cell respiration) materials that enter = carbon dioxide and urea (waste products
How does blood flow through capillaries? (4)very slow at very low pressure = max material exchange extensive branching and narrower lumen reduces the high BP from arteries high hydrostatic pressure at arteriole end = good materials to exit (O2) low hydrostatic pressure at venule end = bad materials to enter (CO2)
What do veins do?carry blood back to the heart at low pressure
How are veins specialized? (4)wide lumen thin walls bec of low BP, no elastic recoil valves to stop backflow and pooling of blood can be compressed by skeletal muscle contraction which allows blood flow against gravity
How do valves prevent backflow? Where is it found?causes unidirectional blood flow which stops blood pooling in veins and heart
How does blood flow through veins? (2)travels at low pressure which makes it difficult to move against gravity has one way valves to maintain circulation of blood and prevent backflow
How do veins transport blood against gravity? (2)they are compressed by contractions of skeletal muscles which causes blood to flow veins run parallel to arteries and can be compressed by arterial bulges created by a pulse
How do you identify the 3 different blood vessels under a microscope?arteries = thick walls with 3 distinct layers small lumen veins = thin walls and wider lumen capillaries = small and not detected under same magnification as arteries and veins
How does the heartbeat occur?started with a group of specialized muscle cells in the right atrium
How is the contraction of the heart myogenic? what does myogenic mean?myogenic means that the signal for cardiac compression comes from the heart muscles itself (cardiomyocytes) not from brain signals
What are the muscles that contract the heart called and where is it located?cariomyocytes are in the wall of the right atrium = the cluster of cells are collectively called the sinoatrial node
How does the sinoatrial node act as a primary pacemaker? (4)it controls the rate at which the heart beats causes around 60 - 100 contractions / minute if it fails then a secondary pacemaker (AV node) maintains the contractions at 40-60 bpm the last tertiary pacemaker (bundle of his) can do contractions at 30-40 bpm
What would happen if there was no pacemaker?fibrillation = the cardiac cells would act independently = irregular and uncoordinated contractions
What is the role of a pacemaker?it causes the cardiac cells to act in unison to cause a sinus rhythm
How does the sinoatrial node stimulate contraction? (4)it sends out an electrical signal and is spread through the walls of the atria and then the walls of the ventricle = stimulates contraction of myocardium (heart muscle tissue) the impulse causes the atria to contract and stimulates another node between the atrium and ventricle 2nd node = atrioventricular node (AV) sends signals down the septum via Bundle of His Bundle of His supplies nerve fibres (purkinje fibres) in the ventricular wall = ventricular contraction
How does the electrical conduction cause 2 beats? (2)due to the delay between the atrial and ventricular contractions this delay causes the ventricles to fill with blood following the atrial contractions = maximizes blood flow
How can the heart rate be increased or decreased? (4)hormonal signalling = sustained slower changes nerve signalling = quick changes changes to blood pressure levels or CO2 concentrations
How does nerve signalling work? (5)pacemaker is under involuntary control from medulla oblongata (Brain stem) 2 nerves that are connected to the medulla regulate the heart rate sympathetic nerve = releases NT noradrenaline = increase heart rate parasympathetic nerve = releases NT acetylcholine = decrease Heart rate triggers quick changes
What are hormones?chemical messengers that are released into the bloodstream to act on target sites
How do hormones change heart rate? example(2 names)HT can have a sustained increase to prep for physical activity w/ hormonal signalling adrenaline (epinephrine) is released by adrenal glands (Above kidney) which increases HT by activating the same chemical pathways as the NT noradrenaline
Describe the cardiac cycle (sis , diarrhea) (4)a heart beat is made up of contraction (systole) and relaxation (diastole) contraction = increases P in atria and ventricles = blood flows from area of high pressure to low pressure Systole: when ventricles contract, AV valves close to stop backflow into atria = blood into arteries (1st sound) bicuspid and tricuspid valves close Diastole: when ventricles relax, semilunar valves close = stops backflow into ventricles = blood into arteries (2nd sound) blood flows out of the heart through the arteries (pulmonary and aortic arteries)
Describe what happens during systole in the cardiac cycle? (5)blood flows into atria + ventricles bec low P bec low V of blood when ventricles is full = atria contacts = increase P in atria to force all blood into ventricles When ventricles contract AV valves close to stop backflow = first sound P increases in contracting ventricles = isovolumetric contraction when ventricular P > BP in aorta = AV opens = blood released in aorta
Describe what happens during diastole? (2)as bllod exits, ventricular P decreases = when below Aortic p the Aortic valve closes to stop backflow (2nd sound) when VP is below AP the AV valve opens - blood can flow from atria to ventricle
Why is aortic pressure always high?because muscles and elastic fibres in artery wall maintains BP
What can happen to the coronary arteries? What does it do?supplies the cardiac tissue with oxygen and nutrients = if it becomes blocked = part of the heart will die and stop working
What causes coronary occlusion?Atherosclerosis = hardening + narrowing of arteries bec of cholesterol
Describe the process of atherosclerosis developing? (6)1) fatty deposits (Atheromas) develop in arteries = reduces lumen size (stenosis) 2) restricted flow = increases P in artery = damaged arterial wall 3) damaged region repaired with fibrous tissue = reduces elasticity of the wall 4) as the smooth lining is degraded = lesion forms (atherosclerotic plaque) 5) if it ruptures = blood clotting starts = forms thrombus (blood clot in vessel) 6) if thrombus is moved = embolus = blockage in a smaller arteriole
What can happen because of coronary occlusion? (3)blood clots = CHD in coronary arteries myocardial tissue needs nutrients from coronary arteries to function so when completely blocked = acute myocardial infarction = heart attack
How is blockage of coronary arteries treated? (3)by-pass surgery creating a stent (tiny tube that can be placed ina vessel to hold it open Balloon angioplasty = balloon inserted in narrow area nad inflated to flatten plaque = artery widened = blood flow improves
What causes CHD? A GODDESS (8)Age = vessels beocme less flexible with age Genetics = hypertension predisposes individuals Obesity = additional strain Diseases = increase risk (diabetes) Diet = rich in saturated fats, salts and alcohol increase risk Exercise= lack of it will increase risk Sex = males are more likely to develop it bec of lower estrogen levels Smoking = nicotine causes vasoconstriction = increases BP
Describe the flow of blood as it completes 1 full circulationBlood enters the heart through the inferior and superior vena cava, to carry deoxygenated blood into the right atrium. The blood the flows into the right ventricle through the open tricuspid valve and once the ventricles are full the valves are closed to prevent backflow of blood. The blood leaves through the pulmonic valve into the pulmonary artery into the lungs to be oxygenated. The pulmonary vein carries oxygenated blood from the lungs into the left atrium. The oxygenated blood goes into the left ventricle. The blood leaves the heart through the aorta and to the body.