1: Lifestyle, Health + Risk (1) Flashcards
Spec points 1.1 - 1.7 - the heart and circulation
why do many animals have a heart and circulation
mass transport is used to overcome limitations of diffusion in meeting the requirements of organisms
What is mass transport?
system of delivering substances around the body
What features must a mass transport system have? (in context of the human body)
requires a pump (heart) ,
medium (blood) for substances to move around the body in
a network of vessels, controlled direction (flow controlled by valves), maintenance of speed (elastic recoil from arteries)
open circulatory system
the blood flows freely through cavities since there are no vessels to conduct the blood.
Closed circulatory system
has vessels that conduct blood through
Why do bigger animals have a closed circulatory system
Bigger animals -> higher metabolic needs, diffusion distance increases, SA:V decreases so open system is inefficient
Single circulatory system
blood enters the heart once, both deoxygenated and oxygenated blood/ blood is mixed
double circulatory system
blood enters the heart twice.
Understand the importance of water as a solvent in transport:
Water is a polar molecule, delta positive hydrogen atoms, delta negative oxygen atoms forms dipole which helps form hydrogen bonds with other water molecules and other polar substances.
why is water a good solvent
Charged nature means that other polar substances are easily dissolvable in it.
High specific heat capacity = a lot of energy is required to change the temperature of water, minimising temperature fluctuations in living things
Liquid = mobile, can carry a lot of substances
hydrogen bonds between water molecules creates adhesion and cohesion which enables effective transport of water. (in plants)
Arteries function + features
- carry oxygenated blood to the body tissues
- small lumen to maintain high blood pressure
smooth inner endothelial lining - thick layer of smooth muscle
- elastic fibres
- lots of collagen fibres in tunica media for strength and support and recoil
Veins
carry deoxygenated blood to the lungs
- large lumen
- thinner layer of muscle and elastic fibres
reduced collagen fibres
valves
why do veins have large lumens and valves
lumens minimise the resistance to flow and valves prevent backflow of blood
why do arteries have smooth endothelial lining and elastic fibres
elastic fibres aid in the stretch and recoil which is used to pump blood around the body
smooth endothelial lining reduces resistance to high pressure blood flow (less friction)
** also thick muscular wall is able to withstand high blood pressures.
why do arteries have a thick layer of smooth muscle
they contract and reax to dilate and constrict blood vessels
Layers of artery wall from out in
Tunica externa, tunica media, tunica intima, endothelium
What are some features of capillaries
1 cell thick = short diffusion distance
Narrow lumen
Small enough to fit between cells
Specialisations of capillaries
many capillaries/ capillary beds + large supply of blood = large diffusion gradient, cover alveoli = large diffusion gradient
1 cell thick = short diffusion distance,
The cardiac cycle:
> Atrial systole - contraction of the atria, blood is expelled from the atria, through the atrioventricular valves to the ventricles.
Ventricular systole - contraction of the ventricles, blood from the ventricles is forced through the semilunar valve into the aorta/ pulmonary artery
Cardiac diastole, heart muscles relax, blood enters into the arteries again from the vena cava and pulmonary vein
What is the heart cycle
Deoxygenated blood from the body -> Vena cava -> Right Atrium (Atrial systole)-> Right AV -> Right ventricle (ventricular systole)-> R. SLV -> Pulmonary artery -> Lungs to get oxygenated -> diastole
Oxygenated blood from lungs -> Pulmonary vein -> Left atrium (atrial systole) -> Left AV -> Left ventricle (ventricular systole) -> L. SLV -> Aorta -> diastole -> rest of the body
why does the left side of the heart have more cardiac muscle?
Left side of the heart has more cardiac muscle because it pumps blood all around the body.
Process of events leading to atherosclerosis
1) damage to endothelium (endothelial dysfunction)
2) Inflammatory response- White blood cells => LDL cholesterol and calcium salts
3) Plaque formation
4) Raised blood pressure because lumen becomes more narrow
Blood clotting process
1) Increased blood pressure,
Further damage to endothelium
2) Cascade of chemical changes, thromboplastin released.
Thromboplastin catalyses the conversion of prothrombin to thrombin.
3) Thrombin catalyses change of fibrinogen to fibrin = fibrin mesh
4) Fibrin mesh collects platelets and calcium ions resulting in blood clot formation
5) Narrows artery = increased blood pressure, blood clot blocs artery further, less blood = less oxygen = less respiration = cell death. 6) Coronary arteries starved of oxygen = heart attack
Brain = stroke
Factors that increase risk of CVD
Age, gender, high blood pressure, smoking, Inactivity, diet
age
heart wall thickens
gender
men at a higher risk of developing CVD
high blood pressure
more risk of damage to arterial walls, resulting in blood clots and atherosclerosis, narrowing artery lumens and increasing risk of heart attack
smoking
nicotine makes platelets more sticky = increasing risk of blood clot + reduces amount of antioxidants in blood
CO binds to haemoglobin in RBCs so RBCs carry less oxygen
inactivity
fat buildup, cholesterol buildup in arteries, narrowing them, increasing blood pressure
diet
high salt intake, fat intake, increases buildup of plaque/ LDLs in arteries
treatments for CVD
antihypertensives, statins, anticoagulants, platelet inhibitors
antihypertensives
- Reduce HBP
Benefits: can take combination of different hypertensives, easy for patients to monitor BP at home using BP monitor
Risks: Low BP = Nausea, fainting, thirst, lack of concentration, arrhythmia
statins
Reduce cholesterol
Benefits: Reduce risk of CVD
Risks: Headaches, dizzy, nausea, tired, weak, constipation, diarrhoea, low platelet count
anticoagulants
reduce blood clotting by preventing platelets from sticking together
Benefits: prevent new atheromas and existing ones from getting larger
Risks: side effects, blood loss, internal bleeding, gastrointestinal bleeding.
Platelet inhibitors
prevents platelets from sticking together
Benefits: Stop new clots from getting larger.
Risks: bruise more easily, heavy bleeding
