Give scientific reasons:
$(1)$ Plaque stimulates/causes the formation of a blood clot on the wall of an artery.
$(2)$ Blood pressure and smoking have a direct relation with obesity.

(N/A) $(1)$ High blood pressure,smoking,and excessive fatty foods damage the endothelium. Plaque is built in such injured parts due to the deposition of fatty materials.
First,injured cells proliferate. Then,unstriated muscles beneath the endothelium associate with it.
Most lipids and cholesterol accumulate in this region. This plaque forms protrusions in the arteries,which provide resistance or obstruction to blood circulation,leading to clot formation.
$(2)$ During smoking,nicotine mixes into the blood,causing arterioles to contract,which increases blood pressure.
In the lungs,the capacity to transport oxygen decreases,causing blood pressure to rise. Carbon monoxide $(CO)$ produced during smoking decreases the oxygen-carrying capacity of hemoglobin,further increasing blood pressure.
In obese individuals,a larger volume of blood must be supplied to tissues,which increases the workload on the heart and consequently raises blood pressure.