Exam questions- blood vessels

Describe the events leading to atherosclerosis.

High blood pressure causes damage to artery endothelium.

This causes an inflammatory response.

WBC enter behind endothelium.

WBC absorb saturated fats & cholesterol.

Fibrous plaque forms. This narrows lumen

This reduces blood flow. This reduces concentration gradients & rate of diffusion.

Blood pressure increases due to positive feedback.

Respiration can’t occur so the cells or tissues die.

Describe the events leading to formation of blood clots.

• Damage to artery endothelium exposes collagen fibres.

• Platelets are activated.

• Thromboplastin is released. Prothrombin converts into thrombin. Thrombin converts fibrinogen into fibrin.

• Fibrin polymerises to form mesh, trapping more platelets & RBC.

• Positive feedback until exposed collagen fibres are covered.

• Too much clotting can lead to blood clots in arteries.

• This reduces conc gradients, rate of diffusion and cell death

explain how atherosclerosis can lead to a heart attack.

blood clot in a coronary artery

This reduces flow of blood

This reduces oxygen supply & conc gradients

Rate of diffusion of oxygen is inadequate.

For respiration to occur, heart cell stops functioning.

Heart fails to contract which causes a heart attack.

how does atherosclerosis lead to a stroke

blood clot in brain artery

This reduces flow of blood.

This reduces oxygen supply & conc gradients

Rate of diffusion of oxygen is inadequate

For respiration to occur, ATP levels drop, brain cells stop functioning.

Significant loss of brain tissue function results in a stroke.