Circulatory System / Lifestyle and Disease

Right Side - Deoxygenated Blood

Vena Cava --> R. Atrium --> Atrioventricular Valve --> R. Ventricle --> Semi-Lunar Valve --> Pulmonary Artery --> Lungs

Left Side - Oxygenated Blood

Pulmonary Vein --> L. Atrium --> Atrioventricular Valve --> L. Ventricle --> Semi-Lunar Valve --> Aorta --> Rest of Body

Left ventricle has thicker, muscular wall - better contraction to pump blood round body

Arteries

• Carry blood away from heart
• Thick walled, muscular
• Elastic tissue - withstand high pressure
• Folded endothelium - expansion

Veins

• Take blood to heart
• Wide
• Contains valves - stop blood flowing backwards

Capillaries

• Smallest vessel
• Metabolic exchange occurs
• Capillary beds - increase surface area
• One cell thick - speeds up diffusion 

Thromboplastin ---> Prothrombin ---> Thrombin ---> Fibrinogen --->  Fibrin + Platelets + Red Blood Cells

• Thromboplastin (protein) released from damaged blood vessel

• Thromboplastin triggers conversion of prothrombin (soluble protein) into thrombin (enzyme)

• Thrombin catalyses conversion of fibrinogen (soluble protein) to fibrin (solid insoluble fibres)

• Fibrin fibres tangle together and form mesh

• Platelets and red blood cells get trapped - forms blood clot

• Wall of artery is made up off several layers

• Endothelium (inner lining) is smooth and unbroken

• Damage occurs to endothelium (e.g. high blood pressure) = inflammatory response - white blood cells move into area

• White blood cells and lipids from blood clump together under endothelium

• form fatty streaks

• Over time, white blood cells, lipids, connective tissue build up and harden

• Form fibrous plaque called ATHEROMA

• Plaque partially blocks lumen of artery - restricts blood flow = increased blood pressure

• Hardened arteries = ATHERSCLEROSIS

• Atheromas increase risk of thrombosis

• Atheroma ruptures endothelium

• Damages artery wall - leaves rough surface

• Thrombosis  is triggered  - blood clot forms at site of rupture

• Blood clot causes blockage of artery or dislodges and blocks another blood vessel

• Blood flow to tissues is restricted - less oxygen reaches tissue = damage

• Heart attack, stroke and deep vein thrombosis - CARDIOVASCULAR DISEASE

Heart Attacks

• Heart muscle supplied with blood by coronary arteries
• Blood contains oxygen needed by heart muscle cells for respiration
• Coronary artery becomes blocked by blood clot 
• Area of heart muscle cut off from blood supply
• Causes myocardial infarction (Heart Attack)

Stroke

• A rapid loss of brain function due to disruption in blood supply to brain
• Caused by blood clot in artery, reduces amount of blood and oxygen to brain

Deep Vein Thrombosis (DVT)

• Formation of blood clot in vein deep inside body - usually happens in leg veins
• Caused by prolonged inactivity

• High blood cholesterol increases risk of CVD
• Cholesterol is a lipid
• Needs to be attached to protein to be moved
• Body forms lipoproteins

High Density Lipoproteins (HDLs)

• Mainly protein
• Transport cholesterol from body tissues to liver - recycled or excreted
• FUNCTION: Reduce total blood cholesterol when level too high

Low Density Lipoproteins (HDLs)

• Mainly lipid
• Transport cholesterol from liver to blood - circulates until needed
• FUNCTION: Increase total blood cholesterol when level too low

High total blood cholesterol level + high LDL level - linked to increased risk of CVD

Antihypertensives - Reduce High Blood Pressure

• Decrease risk of atheromas/blood clots forming

• Diuretics - More urine so amount of blood decreased

• Beta-Blockers - Reduces strength of heart beat

• Vasodilators - Widens blood vessels

Benefits 

Blood pressure monitored at home

Risks 

Palpitations / Fainting / Headaches / Drowsiness / Allergic Reaction / Depression

Plant Statins - Reduce Cholesterol in Blood

• Contain Stanols / Sterols

• Reduce blood cholesterol

• Reduce amount absorbed by gut

Benefits

Reduces risk of CVD

Risks

Reduces risk of absorption of vitamins

Anticoagulants - Reduce Formation of Blood Clots

• E.g. warfarin / heparin

• Artery walls less likely to get damaged

Benefits

Treat people with CVD / blood clots

Prevent new blood clots forming

Risk

Excessive bleeding if injured

Fainting / Allergic Reactions / Osteoporosis

Platelet Inhibitory Drugs - Reduce Formation of Blood Clots

• Prevent platelets clumbing

• Reduce chances of blood clotting = reduce chance of blocked blood vessels

Benefits

Treat those with blood clots / CVD

Risks

Rashes / Nausea / Liver Function Problems / Constant Bleeding

• Organisms take in and use up energy

• Energy for growing, moving, reproducing

Energy budget - amount of energy taken in by organism and amount of energy used up

Energy Input - Energy output = Energy Budget

• Higher intake than output = weight gain

• Lower intake than output = weight loss