Topic 1 Flashcards
what is cardiovascular disease?
diseases of the heart and circulatory system. main form is coronary heart disease or strokes.
what is a closed circulatory system?
blood enclosed within vessels.
what is an open circulatory system?
blood diffuses through body cavities.
what is a single circulatory system?
blood is pumped straight to where gas exchange takes place and continues to the rest of the body.
what is a double circulatory system?
blood travels through the heart twice on one complete journey through the body.
what three things does a circulatory system need?
heart, blood vessels, transport medium.
what is the primary purpose of the heart and circulation?
to move substances around the body.
what is diffusion?
the random movement of molecules or ions from a region of their high concentration to a region of their low concentration.
what is mass flow?
movement down a concentration gradient of a liquid or gas and all the particles it contains due to difference in pressure e.g. blood in the circulatory system.
what is a mass transport system?
a system that transports a substance in bulk from specialised exchange organs to the body cells and to remove metabolic waste in an organism. large organisms cannot rely on diffusion alone to meet their metabolic requirements as it is too slow so they need a mass transport system to move substances rapidly over long distances e.g. xylem in a flowering plant and the circulatory system in an animal.
why is water a polar molecule (also known dipole)?
it has an unevenly distributed electrical charge. the two hydrogen atoms are pushed towards each other forming a v-shaped molecule. the hydrogen end of the molecule is slightly positive and the oxygen end is slightly negative because the electrons are more concentrated at that end. this polarity accounts for many of the biologically important properties of water.
what type of bonding holds water molecules together?
hydrogen bonding as the slightly positively charged end of a water molecule is attracted to the slightly negative ends of surrounding water molecules. this results in water being liquid at room temperature.
what is cohesion?
the attraction between molecules of the same type e.g. two water molecules.
why is water cohesive and how is that useful?
water molecules are very cohesive because they are dipolar. this helps water to flow making it great for transporting substances.
why is it important that water is a solvent?
many chemicals dissolve easily in water due to their dipole nature allowing vital biochemical reactions to occur in the cytoplasm of cells. free to move around in the aqueous environment the chemicals can react, often with water itself being involved in the reaction (hydrolysis and condensation reactions). the dissolved substances can also be transported around organisms in animals via the blood and in plants through the xylem and phloem.
what are the properties of polar molecules?
can dissolve easily in water. their polar groups become surrounded by water and go into solution. they are said to be hydrophilic.
what are the properties of non-polar substances?
do not dissolve in water so are said to be hydrophobic e.g. lipids. to enable transport in blood, lipids combine with proteins to form lipoproteins.
how is water a good solvent?
as water is dipolar, the slightly positive end of a water molecule will be attracted to the negative ion and the slightly negative end of a water molecule will be attracted to the positive ion. the ions will get surrounded by water molecules, they will dissolve.
what is specific heat capacity?
the amount of energy in joules required to raise the temperature of 1cm3 of a substance by 1 degrees.
what are the thermal properties of water?
the specific heat capacity of water is very high because a large amount of energy is required to break the hydrogen bonds. a large input of energy causes only a small increase in temperature, so water warms up and cools down slowly.
how are the thermal properties of water useful?
it helps organisms to avoid rapid changes in their internal body temperature and enables them to maintain a steady temperature even when the temperature in their surroundings varies considerably. this also means that bodies of water in which aquatic animals live do not change temperature rapdily.
what are the properties and function of the left ventricle of the heart?
thicker as have more muscular walls than the right ventricle because it needs to contract powerfully to pump blood all the way round the body. the right ventricle only needs to pump blood to the lungs which is a short distance.
what are the properties and functions of the heart ventricles?
the ventricles have thicker muscular walls than the atria as they have to pump blood out of the heart whereas the atria just pump blood a short distance to the ventricles.
where are the atrioventricular valves located and what is their function?
atrioventricular (AV) valves link the atria to the ventricles and stop backflow into the atria when the ventricles contract. tendons attach the AV valves to the ventricles to prevent them being forced up into the atria when the ventricles contract.
where are the semi-lunar valves located and what is their function?
the semi-lunar (SL) valves link the ventricles to the pulmonary artery and the aorta and stop backflow into the heart after the ventricles contract.
how do valves prevent backflow?
the valves only open one way which is dependent on relative pressure of the heart chambers. if there is higher pressure behind a valve, it is forced open but if there is higher pressure in front of the valve it is forced shut. this means blood only flows in one direction through the heart.
what is the structure of an artery?
tunica intima- endothelial cells
tunica media- smooth muscle
tunica externa- elastin and collagen (connective tissue)
how does the structure of an artery relate to it’s function?
arteries mass transport blood AWAY from the heart. smooth endothelial cells minimise friction. thick muscular walls contain the high blood pressure. smooth muscle fibers contract rhythmically on the blood, exerting pressure. elastic fibers absorb the high pressure, expand and ‘smooth’ large pressure changes and ensure a continuous blood pressure. the elastin allow the vessel to stretch as blood surges through preventing damage. the collagen provides structural support and allows a strong and flexible vessel. as pressure falls the artery recoils releasing energy and pushes the blood on it’s way.
what is vasoconstriction and vasodilation?
hormones and the sympathetic nerves can stimulate arteriole smooth muscle to contract. vasoconstriction and vasodilation control and direct blood flow in the body as required.
vasodilation= arteriole muscle relaxation
vasoconstriction= arteriole muscle constriction
what is the structure of a capillary and how does it relate to it’s function?
smaller in diameter than the cells they supply allowing close and intimate contact. the endothelium, supported on the basement membrane, is one cell thick allowing easy exchange across the capillary. fenestrations (gaps) between endothelial cells increases the rate of exchange with tissues. very low blood pressure at the capillary produces a low velocity of blood due to friction with the capillary wall preventing damage to the lung. small lumen, just large enough for a red blood cell to squeeze through. no pulse and no valves.
what is the structure of a vein?
tunica intima- endothelial cells
tunica media- less smooth muscle
tunica externa- little elastin and collagen
how does the structure of a vein relate to it’s function?
veins carry blood at low pressure and velocity. venous walls do not require the thickness and strength of arteries to contain high blood pressure. pressure differences within the venous system are low. valves ensure blood flows only towards the heart after leaving the capillaries. muscles pushing on the veins increase localised pressure and push blood producing flow. relatively large lumen. little elastic tissue in the wall due to low pressure with no surges. no pulse.
what is the cardiac cycle?
the cardiac cycle is an ongoing sequence of contraction (systole) and relaxation (diastole) of the atria and ventricles that keeps blood continuously circulating round the body. the volume of the atria and ventricles changes as they contract and relax. pressure changes also occur due to the changes in chamber volume (decreasing volume increases pressure).
what happens in phase 1 of the cardiac cycle (Atrial systole)?
blood returns to the heart due to the action of skeletal muscles involved in breathing. blood under low pressure flows into the left and right atria from the pulmonary veins and the vena cava. as the atria fill the increasing pressure of blood forces the AV valves open. the ATRIA WALLS CONTRACT forcing blood into the ventricles.
what happens in phase 2 of the cardiac cycle (Ventricular systole)?
the VENTRICLES CONTRACT from the base of the heart upwards, increasing pressure in the ventricles. the pressure forces open the SL valves and pushes blood up and out through the pulmonary arteries and aorta. the pressure of blood against the AV valves close them and prevents backflow into atria.
what happens in phase 3 of the cardiac cycle (Cardiac diastole)?
the atria and ventricles then relax. elastic recoil of the relaxing heart walls lowers pressure in the atria and ventricles. blood under high pressure in the pulmonary arteries and aorta is drawn back towards the ventricles closing the SL valves and preventing backflow into the ventricles. the coronary arteries fill during diastole. low pressure in the atria helps draw blood into the heart from the veins.
what causes the sounds we recognise as a heartbeat?
the AV and SL valves closing. the first sound ‘lub’ is caused by the closing of the AV valves and the second ‘dub’ by the closing of the SL valves.
how does the blood move at each stage of the cycle?
from high pressure to low pressure.
what is atherosclerosis?
the disease process that leads to coronary heart disease and strokes. in atherosclerosis fatty deposits can either block an artery directly or increase its chance of being blocked by a blood clot (thrombosis).
what course of events happen in atherosclerosis? (1)
endothelial dysfunction: the endothelium becomes damaged as a result of high blood pressure (puts extra strain on the layer of cells) or toxins from cigarette smoke in the bloodstream.
what course of events happen in atherosclerosis? (2)
inflammatory response: the inner lining of the artery is breached so white blood cells leave the blood vessel and move into the artery wall. these cells accumulate chemicals from the blood, particularly cholesterol. a fatty deposit builds up called an atheroma.
what course of events happen in atherosclerosis? (3)
plaque formation: calcium salts and fibrous tissue build up at the site resulting in a hard swelling called a plaque on the inner wall of the artery. the build-up of fibrous tissue means that the artery wall loses some of its elasticity.
what course of events happen in atherosclerosis? (4)
raised blood pressure: plaques caused the lumen to become narrower leading to a rise in blood pressure. this causes a positive feedback cycle- plaques lead to raised blood pressure but raised blood pressure increases the chance that further plaques will form as endothelial damage in other areas becomes more likely.
why does blood clotting occur inside arteries?
usually blood does not clot inside blood vessels due to the smooth endothelium lining that also has a substance on its surface that repels the platelets. if there is atherosclerosis however and the endothelium is damaged, due to rupture of an atheroma, platelets come into contact with the damaged surface and exposed collagen and the clotting cascade is triggered.
what are the stages in the clotting cascade? (1)
platelets stick to the damaged artery wall and to each other, forming a platelet plug. platelets and the damaged tissue release a protein called thromboplastin. thromboplastin release triggers the clotting cascade.
