a. elastic arteries b. muscular arteries c. arterioles Factors that aid venous r

Question

a. elastic arteries b. muscular arteries c. arterioles Factors that aid venous return include all except: a. activity of skeletal muscles b. venous valves 20. b. pressure change in d. urinary output The pulse pressure is a. systolic pressure plus diastolic pressure b. systolic press c. systolic pressure divide by diastolic pressure d. none of t 21. 22. Peripheral resistance a. decrease with increasing length of the blood vessel b. increase as blood diameter of blood vessel increase c. increase as blood viscosity increases d. all of the above are correct 2. Which of the following chemicals does not help reg a. ADH 23. b. atrial natriuretic peptide c. angiote Mechanisms that help regulate blood pressure include a. nervous control that operates via reflex arcs involving ba chemoreceptors and higher brains receptors b. chemical receptors such as atrial natriuretic factors c. renal via the renin-angiotensin system d. all of the above are correct 24. 25. The hepatic portal vein a. is actually an artery b. carries nutrient-rich blood to the liver c. carries oxygen-rich blood from blood to the viscera d. carries blood from the liver to the inferior vena cava

Explanation / Answer

20. Factors that aid venous return include all except:

D. Urinary Output

Note: Venous return is the rate of blood that returns to the heart from whole body. It is generallly affected by many factors. Veins are arranged around the skeletal muscle. So when the muscle contracts it makes the veins squeeze, that makes blood flow through the veins. Also the venous valves makes blood flow through unidirectionally, enhancing the blood flow through vein. An increased pressure in the abdomen and thorax increase the pressure gradient making blood flow towards the heart. But Urinary output has no direct effect in venous return.

21. The pulse pressure is:

B. Systolic pressure minus diastolic pressure.

Note: Pulse pressure is measured as the difference between systolic and diastolic pressure in mm Hg unit. For example, in resting blood pressure the systolic and diastolic pressure are 120 / 80 mmHg, so the pulse pressure is 40 mm Hg. Normal range of pulse pressure is 30-50 mm Hg. It is an important indicator of heart health.

22. Peripheral resistance:

C. increases as blood viscosity increases.

Note: Peripheral resistance is the resistant of blood flow through blood vessels that needs to be overcome to circulate properly. It generally follows fluid dynamic and can be measured using Poiseuille equation:

Resistance = (8 * Length of the vessels * viscocity of blood) / [? * (radius of blood vessel)4]

So as you see Peripheral Resistance increases as length of the vessel and blood viscocity increases and it decreases as diameter (or radius) of the vessels increases. So among the 4 options only one is given correctly, that is it increases as viscocity increases.

24. Mechanisms that help regulate blood pressure include:

D. all of the above are correct.

Note: There are many factors that regulate blood pressure. Managing the cardiac output and blood vessel diameter is effective way to control blood pressure. Baroreceptors on blood vessels detects arterial blood pressure and chemoreceptors detect blood concentration of CO2, O2 and blood pH. Higher brain regions asuch as cortex, limbic region and hypothalamus gives signal to cardiovascular system to control blood pressure. Vassomotor center regulates blood vessels diameter, controlling the blood pressure.

Atrial natriuretic peptide (ANF) are released from atria of the heart, and it lowers blood pressure by vasodillation and increasing exretion of water and Na+ from kidney.

Renin-angiotensin system is a very effective in increasing blood pressure. Renin which is secreted from Juxtaglomerullar cells, converts angiotensinogen to angiotensin I, which is then converted to angiotensin II. Angiotensin II effectively increase blood pressure by making kidney reabsorb/retain water and Na+, constricting blood vessels, releasing of aldosteron.

25.. The hepatic portal vein:

B. Carries nutrient rich blood to liver.

Note: Hepatic portal vein is very important vein of the body. It takes blood from small and large intestine, pancrease, spleen and gall bladder. Hepatic portal vein is formed by conjunction of splenic and super mesenteric veins. The blood is taken into the liver from all these area for filtration, before going back to heart.

P.S. The question number 23. is cropped. But judging from the options given I am assuming that the question is:

Which of the following chemicals does not help regulate blood pressure?

The correct option should be D.

As ADH, atrial natriuuretic peptide and renin-angiotensis all helps in blood regulation. I have discussed about ANP and renin-angiotensin in an answer previously given.

Anti diuretic hormone (ADH) is produced by hypothalamus and secreted by posterior pituitary. It helps increasing blood pressure by making kidney retain more water.

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