4.4 Circulation Flashcards
give 4 features of mass transport systems
- system of vessels that carry substances
- making sure substances move in the right direction
- moving materials fast to supply the needs of the organism
- suitable transport medium
describe a single circulatory system
heart pumps deoxygenated blood to the organs of gas exchange, where blood takes in oxygen and gives up carbon dioxide at the same time
blood then travels to the rest of the body, giving up oxygen to cells before returning to the heart
describe a double circulatory system
circulation that involves 2 systems; pulmonary and sytemic circulation
pulmonary circulation - deoxygenated blood travels from the heart to lungs and returns to heart as deoxygenated blood
systemic circulation - oxygenated blood leaves heart and flows around body, returning deoxygenated blood back to the heart
give functions of the cardiovascular system
delivers materials needed by body cells carries away waste products carries hormones forms part of the defense system distributes heat
describe function of plasma
transports food products, nutrients, hormones etc
maintains body temperature
acts as a buffer to pH changes
contains platelets
describe what erythrocytes are
red blood cells
contain haemoglobin which binds to oxygen
no nucleus and biconcave shape gives a large sa:v ratio to aid oxygen diffusion and able to pack in more haemoglobin
describe what leucocytes are
white blood cells
defend body against infection
several types: neutrophils, monocytes, eosinophils and lymphocytes
give function of neutrophils and monocytes
engulf and digest pathogens by phagocytosis
give function of eosinophils
involved in allergic reaction responses + protection against viruses and parasites
give function of lymphocytes
natural killer cells
vital to immune system
formation of antibodies
describe function of arteries and how it is adapted for the function
carries blood away from heart towards body cells.
has external layer of tough tissue
artery wall has elastic fibres and smooth muscle
smooth lining = easy blood flow
lumen is small = carries high pressure blood
lots of elastic fibres = stretches to accomodate high volumes of blood
describe function of capillaries and how it is adapted for the function
branch between cells small vessels blood travels slow - more diffusion blood is oxygenated thin walls allow rapid diffusion (epithelial cells)
describe function of veins and how it is adapted for the fucntion
carries blood back to the heart
carries low pressure blood
has a large lumen
describe the events in the cardiac cycle
- vena cava transports deoxygenated blood from the body to right atrum
2. right atrium fills with blood tricuspid valves open atrium contracts blood enters right ventricles semi-lunar valves prevent backflow
- right ventricles contract
blood flows into pulmonary artery
travels to lungs
tricuspid valves close - oxygenated blood enters left side of heart by pulmonary veins
blood retuns to left atrium
atrium contracts and blood flows into left ventricle
bicuspid valves prevent backflow - left ventricle pumps blood into aorta
aorta carried blood to rest of body
describe the process of controlling the heart beat
- heartbeat starts in sinoatrial node
SAN sends impulses across atria walls causing them to contract
annulus fibrosus (tissue between atria and ventricles) prevents impulse from spreading to ventricles - causes delay - impulses reach atrioventricular node
impulse passed via Bundle of His to the ventricles - bundle of His splits into 2 branches
impulse carried into Purkyne tissue
carries impulse down septum + through ventricles - impulse causes ventricular contraction from apex upwards, squeezing blood out of the heart.
give the equation of carbon dioxide dissolving in blood + reacting with water. name the enzyme controlling this reaction.
O2 (aq) + H2O « H2CO3 « HCO3- + H+
carbonic anhydrase controls the reaction
where is most carbon dioxide carried?
- in solution in plasma
- combines with haemoglobin to form carbaminohaemoglobin
- transported in cytoplasm of red blood cells as hydrogencarbonate ions
describe what happens in the blood when there is a high concentration of carbon dioxide
at high concentration of CO2, carbonic anhydrase catalyses the formation of carbonic acid
describe what happens in the lungs when there is low concentration of carbon dioxide
at low CO2 concentration, carbonic anhydrase catalyses reverse reaction + frees carbon dioxide out of blood and into the lungs
what ions are formed when carbonic acid dissociates?
H+ and HCO3- ions
in the formation of blood clots, platelets release serotonin + thromboplastin. give the function of both.
serotonin- causes the smooth muscle of blood vessel to contract which cuts off blood flow to damaged area
thromboplastin - enzyme that leads to the formation of clots
describe the blood clotting cascade
- thrombocytes (platelets) stick to exposed collagen fibres, forming a plug.
thrombocytes become activated + releasing clotting factors through thromboplastins - thromboplastins convert prothrombin (inactive plasma protein0 into thrombin (active plasma protein)
requires Ca2+ and vitamin K
catalysed by thrombokinase - thrombin catalyses the conversion of soluble fibrinogen into soluble fibrin
fibrin forms a mesh that traps red blood cells and strengthens platelet plug, forming a clot - blood clot is eventually reabsorbed by fibrinolysis
controlled by enzyme plasmin
define atherosclerosis
condition in which yellow fatty deposits build up on arttey linings, causing them to narrow
describe how an atheroma is formed
- slight damage to endothelial cells lining the artery can lead to a build-up of lipids
- blood platelets form a cap over the fatty plaque which narrows the artery
- any further damages causes clot formation which can block the whole artery and have fatal consequences
why does atherosclerosis usually occur in arteries?
blood in arteries flows fast under high pressure = more strain on endothelium lining
in veins, pressure is low so damage is less likely
describe the stages of atherosclerosis
- body’s inflammatory system begins + white blood cells arrive at site of damage
cells accumulate chemicals from blood e.g cholesterol - this leads to an atheroma forming on endothelial lining
- fibrous tissue + calcium salts build up around atheroma, forming a hardened plaque
- hardened area means part of the artery wall hardens so it is less elastic than it should be
what are the effects of atherosclerosis?
lumen of artery becomes smaller
this increases blood pressure so it is harder to pump blood
raised blood pressure = more endothelial damage = more plaques
=increased blood pressure
consequences of atherosclerosis
aneurysms raised blood pressure stroke angina myocardial infarction
identify the non-modifiable risks of atherosclerosis
genes
age
gender
identify the modifiable risk factors of atherosclerosis
smoking exercise weight stress diet
