Topic 1 Flashcards
Explain why many animals need a heart and circulatory system
- heart needed to pump/move blood around the body
- many animals have a small surface area ratio to volume
- a circulatory system is needed to overcome limitations of diffusion
- blood needs to pump molecules around body
Explain what is meant by a double circulatory system?
- blood flows twice through the heart for one circuit
- blood goes through heart to lungs and rest of the body
What are the properties of water that make it an ideal transport medium ?
- water is a solvent
- water molecules surround ions
- H bonds form between water and solute
- water is liquid so has the ability to flow
What is the difference between arteries and capillaries
- arteries have thick wall where as caps are one cell thin
- arteries have lots of collegen where as caps have none
- arteries have lots of muscle where as caps have none
- arteries have lots if elastic tissue where as cap have none
Explain how the structure of an artery wall is adapted to both withstand and maintain high blood pressure
- lots of collagen which provides strength to withstand pressure
-muscle tissue allows contraction of lumber - elastic fibres stretch and recoil which allows lumen to grow and go back
Explain how the structure of a vein relates to its function
- large lumen to reduce resistance to blood flow back to heart
- valves prevent backflow of blood
- thin layer of muscular tissue to maintain blood pressure
- smooth endothelium to reduce resistance to blood flow
Describe the Cardiac cycle
The cardiac cycle consists of three stages: atrial systole, ventricular systole and diastole.
During atrial systole, the atria contract forcing atrioventricular valves open and blood flows into ventricles
During ventricular systole, ventricles contract, semi lunar valves open as oxygenated blood is forced out of the heart through the aorta to the body and through the pulmonary artery to the lungs.
Diastole - atria and ventricles relax, semi lunar valves close
Explain differences between pressure changes in left atrium and left ventricle during cardiac cycle
- pressure changes are smaller in atrium than in ventricle
- the atrium has less cardiac muscle than ventricle
- the atrium does not have to use blood as far as ventricle has to
- the increase in pressure happens in the atrium before ventricle
-atrial systole has to happen before venatical system in order for the ventricle to fill with blood
-therefore increasing the atrial pressures which increases pressure in ventricles
Describe how atherosclerosis occurs
- damage to endothelial cells
- inflammatory response
- large white blood cells enter
- build up of cholesterol
- atheroma forms
- Calcium salts and fibrous tissue present
- elasticity reduced
- artery narrows
- blood pressure increases
How does blood clotting process occur
-thromboplastin released which starts cascade
- concerts prothrombin to thrombin
- catalysed conversion of fibrinogen to fibrin
- firin creates mesh fibres
-platelets and blood cells get trapped in mesh
-form a blood clot
Explain how the diet of a person could affect the development of CVD
- high salt intake
- increases blood pressure
- high blood pressure damages entholeoum
- higher intake on saturated fats / LDLS increase risk f atheroma forming
Describe the roll of LDLS in the development of atherosclerosis
-LDLs carry cholesterol in the blood
-cholesterol is deposited to atheroma in the endothelium of artery
Describe how very high blood pressure could result in atherosclerosis
- high blood pressure damages endothelium of artery
- this causes a inflammatory response
- white blood cells and cholesterol accumulate
- Atheroma forms
-calcium slates and fibrous tissue build up
-Plaque is formed
Explain how atherosclerosis can result in damage to heart muscle
-narrowing of lumen in arteries
- reduced blood flows and oxygen to cardiac muscles
- reduces aerobic respiration
Explain why high level of sugar in a persons diet could lead to obesity
-energy intake higher than energy output
-excess sugar can be stored as fat
- leads to weight gain
- obesity indicates by BMI above 30 or was it it hip ratio
