1B Heart, Circulatory system Flashcards
veins
vessels that carry blood towards the heart
arteries
vessels that carry blood away from the heart
capillaries
tiny vessels that spread throughout the tissues of the body
lumen
then central space inside the blood vessel
arterial system
the system of arteries in the body
arterioles
the very smallest branches of the arterial system, furthest form the heart
peripheral arteries
arteries further away from the heart but before the arterioles
venules
the very smallest branches of the venous system, furthest from the heart
inferior vena cava
the large vein that carries the returning blood from the lower parts of the body to the heart
superior vena cava
the large vein that carries the returning blood form the supper parts of the body to the heart
venous system
the system of veins in the body
semilunar valves
half-moon shaped, one-way valves found at frequent intervals in veins to prevent the backflow of blood
name the semi-lunar valves in the heart
pulmonary valve
aortic valve
name the atrioventricular valves
tricuspid valve
mitral valve / bicuspid valve
septum
the thick muscular dividing wall through the centre of the heart that prevents oxygenated and deoxygenated blood form mixing
cardiac muscle
the special muscle tissue of the heart, which has an intrinsic rhythm and does not fatigue
myoglobin
a respiratory pigment with a stronger affinity for oxygen than haemoglobin
right atrium
the upper right-hand chamber of the heart that receives deoxygenated blood form the body
left atrium
the upper left-hand chamber of the heart that receives oxygenated blood form the lungs
right ventricle
the lower chamber that receives deoxygenated blood form the right atrium and pumps it to the lungs
left ventricle
the chamber that receives oxygenated blood form the left atrium and pumps it around the body
tricuspid valve
the valve between the right atrium and the right ventricle that prevents backflow of blood form the ventricle to the atrium when the ventricle contracts
bicuspid valve
the valve between the left atrium and the left ventricle that prevents backflow of blood into the atrium when the ventricle contracts
tendinous cords / valve tendons / heartstrings
cord-like tendons that make sure the valves are not turned inside out by the large pressure exerted when the ventricles contract
pulmonary artery
the blood vessels that carry deoxygenated blood from the heart to the lungs
pulmonary veins
the blood vessels that carry oxygenated blood back form the lungs to the heart
aorta
the main artery of the body; it leaves the left ventricle of the heart carrying oxygenate blood under high pressure
systole
the contraction of the heart
diastole
when the heart relaxes and fills with blood
cardiac cycle
the cycle of contraction and relaxation in the heart
double circulation system
a circulation that involves two separate circuits
one of deoxygenated blood flowing from the heart to the gas exchange organs to be oxygenated before returning to the heart
and one of oxygenated blood leaving the heart and flowing around the body, returning as deoxygenated blood to the heart
systemic circulation
carries oxygenated blood from the heart to the cells of the body where the oxygen is used, and carries the deoxygenated blood back to the heart
oxygenated blood
blood that is carrying oxygen
deoxygenated blood
blood that has given up its oxygen to cells in the body
pulmonary circulation
carries deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart
Why do unicellular organisms not need specialised transport systems?
• small diffusion distance
• large sa:vol ratio
• low metabolic demands
advantages of a closed circulatory system are:
• the pressure can be increased to make blood flow more quickly
• the flow can be directed more precisely to the organs that need most oxygen and nutrients
Risk
the probability that an event will take place
risk factors
factors which affect the risk of an event happening contribute to the chances of developing a disease
correlation
a strong tendency for two sets of data to change together
e.g. mortality data from atherosclerosis may change in a similar pattern to smoking
causation
when a factor directly causes a specific effect
leucocytes
white blood cells; there are several different types which play important roles in defending the body against the entry of pathogens and in the immune system
explain why the total surface area of capillaries needs to be high
- more plasma is able to leave the capillaries
- results in faster diffusion
- more capillaries are in contact with the cells in the tissue
- diffusion distance is short
explain the advantages of storing thromboplastin inside platelets
- to keep thromboplastin separate from prothrombin
- so that prothrombin will not be converted into thrombin
- the blood clotting process will be prevented
- to have thromboplastin available when needed
platelets
cell fragments involved in the clotting mechanism of the blood
megakaryocytes
large cells that are found in the bone marrow and produce platelets
oxyhaemoglobin
the molecule formed when oxygen binds to Hb
carbaminohaemoglobin
the molecule formed when carbon dioxide combines with haemoglobin
carbonic anhydrase
the enzyme that controls the rate of the reaction between carbon dioxide and water to produce carbonic acid
Bohr effect
the name given to changes in the oxygen dissociation curve of haemoglobin that occur due to a rise in carbon dioxide levels and a reduction of the affinity of haemoglobin for oxygen
fetal haemoglobin
a form of haemoglobin found only in the developing fetus with a higher affinity for oxygen than adult haemoglobin
serotonin
a chemical that causes the smooth muscle of the blood vessels to contract, narrowing them and cutting off the blood flow to the damaged area
thromboplastin
an enzyme that sets in progress a cascade of events that leads to the formation of a blood
clot
prothrombin
a large, soluble protein found in the plasma that is the precursor to an enzyme called thrombin
thrombin
an enzyme that acts on fibrinogen, converting it to fibrin during clot formation
precursor
a biologically inactive molecule which can be converted into a closely related biologically active molecule when needed
fibrinogen
a soluble plasma protein which is the precursor of the insoluble protein fibrin
fibrin
an insoluble protein formed from fibrinogen by the action of thrombin that forms a mesh of fibres that trap erythrocytes and platelets to form a blood clot
explain why antioxidants in the diet reduce the risk of CVD
• because antioxidants reduce free radicals
• therefore damage to the lining of blood vessel will be reduced
• therefore reducing atheroma formation
