Answer :
Final answer:
High blood pressure can be caused by increased peripheral resistance and excess angiotensin II, both of which raise the resistance the heart must overcome to pump blood. In contrast, vasodilation lowers blood pressure and does not contribute to hypertension.
Explanation:
Understanding High Blood Pressure Causes
High blood pressure, or hypertension, can be influenced by several physiological factors. Among the options provided, let's evaluate each:
- Increased peripheral resistance - This occurs when the blood vessels become narrower (vasoconstriction), which raises the pressure required to pump blood through them. This is a key factor in high blood pressure.
- Vasodilation - This is the opposite effect, where blood vessels widen. It typically leads to lower blood pressure, so it is not a cause of hypertension.
- Excess angiotensin II - Angiotensin II is a potent vasoconstrictor that raises blood pressure by increasing peripheral resistance and stimulating the release of aldosterone, which promotes sodium retention and increases blood volume. Thus, an excess of this hormone can indeed lead to high blood pressure.
Considering the above, the correct answers include both increased peripheral resistance and excess angiotensin II, as they both contribute to elevated blood pressure. Therefore, the best choice from the options is:
Answer: Increased peripheral resistance and excess angiotensin II (Option d)
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