Answer:Ultraviolet radiation. Invisible rays that are part of the energy that comes from the sun, can burn the skin, and cause skin cancer. UV radiation is made up of three types of rays -- ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC).
Explanation:Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays.
Increasing evidence supports the importance of hemodynamic forces that are directly related to the work of the heart as the primary triggering event of atherosclerosis and atherothrombosis. The factors that primarily determine the work of the heart include systolic blood pressure (BP), blood viscosity, and the volume of blood the myocardium has to pump.
The relationship between BP and viscosity is such that, given a constant systolic BP, if blood viscosity increases, then the total peripheral resistance (TPR) will necessarily increase, thereby reducing blood flow. Conversely, when viscosity decreases, blood flow and perfusion will increase. Because of the dependence of systemic arterial BP on cardiac output and TPR, if blood viscosity and TPR rise, systolic BP must then increase for cardiac output to be maintained. Consequently, blood viscosity has been established as a major determinant of the work of the heart and tissue perfusion [1]. Since increased viscosity requires a higher BP to ensure the same circulating volume of blood, both the burden on the heart and the forces acting on the vessel wall are directly modulated by changes in blood viscosity.
Three important studies helped establish the relationship between blood pressure and blood viscosity. The earliest study observed 49 normal subjects and 49 patients with untreated essential hypertension, showing a direct correlation between BP and blood viscosity among both normotensive and hypertensive subjects (p<0.001). Systolic blood viscosity was 8 to 10% higher in hypertensive patients compared with normotensive controls, and diastolic blood viscosity was 16 to 28% higher in hypertensive patients. Subgroups each comprised of 25 subjects having matched hematocrits were also compared, and viscosity remained significantly higher in hypertensive subjects (p<0.05). [2]
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Answer:
B) difference in water density
Explanation:
The deep ocean currents are the cold ocean currents. They appear in the Arctic and Antarctic circles. As the warm ocean currents come from the low latitudes toward the high latitudes, they bring in warmer water on the surface. They start to cool off though as the near the high latitudes, so gradually they become cold ocean currents. As they become cold, the water is sinking below the less dense warmer water that is coming from behind, making a turn in the opposite direction and moving as deep ocean current toward the low latitudes. Once it reaches the low latitudes, this water will get warmer, and it will move toward the high latitudes, and the process constantly continues.
Answer:
Invasive species compete for the same natural resources such as food and water which the native species also need for survival.
Explanation:
Invasive species upset the stability of the ecosystem because the prey in their new environment does not have the needed defense against them. They also upset the food chain, consume so much, and overpopulate in the new territory thus causing the extinction of the native species.
The introduction of brown tree snakes in Guam disrupted the ecological system as their population increased rapidly because their preys in this new environment lacked the ability to defend themselves against the brown tree snakes. For this reason, more than twelve native birds in the Guam Islands went into extinction. They also consumed the natural resources needed for the survival of the native species.
