| 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 circulation | Blood 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. |
