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topic 1 bio lifestyle, health and risk - Coggle Diagram
topic 1 bio lifestyle, health and risk
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water in transport
water is medium where all metabolic reactions happen and where all substances are transported around the body
- water composed of hydrogen and oxygen
- one atom of oxygen combines with two atoms of hydrogen by sharing electrons (covalent bonding)
- sharing of electrons is uneven between oxygen and hydrogen atoms
- oxygen atom attracts electrons more strongly than hydrogen atoms causing weak negatively charged region on oxygen atom and opposite on hydrogen
- separation of charge due to electrons in covalent bonds being unequally shared is called a dipole
- when a molecule has one end that is - and one that is + charged it is a polar molecule
- water is polar
- hydrogen bonds form between the positive and negatively charged regions of water molecules as a result of the polar nature of water
- hydrogen bonds are weak when few in number so are constantly breaking and reforming so means water molecules flow in a liquid state
polar nature of water gives it properties that make it good at transporting substances
- water is cohesive
- water is solvent
cohesion and adhesion
- hydrogen bonds between water molecules allow for strong cohesion between molecules
- cohesion attraction of water molecules to eachother
- water also able to bond to other molecules (adhesion)
- forces of cohesion and adhesion between water and surroundings means it can flow easily
- water pulls other water molecules along
- water adheres to sides of a vessel
solvent
- as water is polar molecule ions e.g sodium and chloride ions and covalently bonded polar substances e.g glucose will dissolve in it
- water molecules surround charged particles; positive parts of water are attracted to negatively charged particles and vice versa
- ions separate from each other e.g sodium chloride separates into sodium ions and chloride ions
- ions surrounded by water molecules dissolve
- allows chemical reactions to occur in cells as dissolved solutes are more chemically reactive when free to move about
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cardiac cycle
- a series of events take place in one heart beat including muscle contraction and relaxation
- contraction called systole and relaxation called diastole
volume and pressure changes
- contraction causes decrease in volume in corresponding chamber of the heart which then increases when muscle relaxes
- volume changes lead to corresponding pressure changes
- volume decrease pressure increase and vice versa
- throughout cycle valves open and close as a result of pressure changes
atrial systole
- walls of atria contract, atrial volume decreases, atrial pressure increases
- pressure in atria rises above that in ventricles and blood forced through the open av valves into ventricles
- slight increases in ventricular pressure and chamber volume as ventricles get blood
- ventricles relaxed atp so ventricular diastole concedes with atrial systole
ventricular systole
- walls of ventricles contract, ventricular volume decreases, ventricular pressure increases
- pressure on ventricles rise above that in atria so forces av valves to close preventing back flow
- pressure in ventricles rise above that in aorta and pulmonary artery so forces semi lunar valves open and blood forced into arteries and out of heart
- during atria is relaxing so atrial diastole coincides with ventricular systole
- blood flow to heart continues so relaxed atria begin to fill with blood again
cardiac diastole
- ventricles and atria both relaxed
- pressure in ventricles drops below that in aorta and pulmonary artery forcing semi lunar valves to close
- atria continue to fill with blood
- blood returns to heart via vena cava and pulmonary vein
- pressure in atria rises above that in ventricles forcing av valves open and blood flows into ventricles without needing atrial systole
- cycle then begins again
atherosclerosis
- known as hardening of arteries caused by damage to endothelium of an artery followed by inflammatory response
- progressive disease
- in healthy artery endothelium is smooth and reduces friction
steps
- damage to endothelium cause by high blood pressure or high levels of cholesterol, smoking, diabetes, obesity and old age
- inflammatory response occurs and wbc e.g macrophages accumulate in the damaged area
- lipids and cholesterol clump together with macrophages under endothelium and form fatty build up
- platelets can also adhere to fatty deposit
- this all forms plaque called an atheroma
- atheroma narrows the lumen of artery reducing and restricting blood flow and raises bp
- over time can harden reducing elasticity of artery wall and increasing bp
blood clotting
- prevents excess blood loss, entry of pathogens, and provides a barrier or scab under which wound healing can occur
- process of blood clotting is known as thrombosis
steps
- damaged blood vessel releases a protein called thromboplastin
- calcium ions from the plasma, with thromboplastin trigger conversion of soluble prothrombin protein into enzyme thrombin
- thrombin catalyses conversion of soluble protein fibrinogen into insoluble protein fibrin
- fibrin fibres mesh together trapping platelets and rbc
- forming a blood clot
- atheromas can increase risk of a blood clot as plaque deposit of atheroma can rupture through endothelium damaging and forming rough surface
- then triggers thrombosis
- combo of atheroma and blood clotting can completely block an artery restricting blood flow and oxygen in the blood so reducing respiration of surrounding cells, tissue and organs
- blood clots can dislodge and move around body; if reach brain can cause a stroke
- blood clotting can cause heart attacks and strokes
stroke
- a sudden loss of brain function in a localised area due to disruption of blood flow to brain
- blood clot blocks arteries supplying the brain
- leads to reduced blood flow and oxygen to cells and brain reducing respiration
- cells in affected part of brain cannot produce ATP so function reduced
- stroke cause by blood clot is ischemic stroke
heart attack
- coronary heart disease caused by formation of atheromas and blood clots in the coronary arteries
- blood flow to areas of heart is restricted and oxygen delivery to effected cells is decreased reducing respiration
- cells can't produce ATP
- cells can no longer contract reducing force generated by heart when beats
- cells can die causing permanent damage
- leads to myocardial infarction
- complete failure may occur if large areas of heart are affected
- symptoms include chest pain, shortness of breath, sweating