Birds Have a Higher Body

¶ … birds have a higher body temperature when compared to mammals. One would think that mammals would have higher body temperatures, but the need to better insulate their eggs outside of their bodies creates a need for a much higher body temperature in birds. The need to insulate eggs on the outside of the body requires that birds have more heat to their bodies. Their overall metabolic rate is also higher than mammals, making them generate more heat at a metabolic cost. Moreover, birds do not have sweat glands to help regulate their internal temperatures like mammals do. Thus, birds tend not to loose heat through their skin and glands. As such, they are hotter internally than mammals.

Question 2

An injection of concentrated sodium chloride triggers osmotic thirst because the body's kidneys send a chemical message to the brain that signifies changing levels of sodium. Here, Kalat states that "if your kidneys cannot regulate your water and sodium adequately, your brain gets signals to change your drinking or sodium intake," (Kalat 308). Therefore, when you have changes in the levels of sodium, like in the case of being injected with a concentrated sodium chloride, the body sends signals that more water is needed to compensate for such high levels. But this injection also triggers osmotic thirst because the body also needs to regulate salt levels as well in cases of rising sodium in the body. On the other hand, an injection of glucose will not trigger the same reaction. Injections of glucose cause thirst, but not osmotic thirst that aim to lower sodium levels. Glucose increases blood sugar, and has nothing to do with salt levels. This is because with higher levels of glucose, there is more water expelled with urination, causing the need for thirst increasing water levels, but not necessarily salt levels.

Question 3

If the water you drank leaked out of a tube in your stomach, your drinking would definitely change. Such a loss of water would trigger hypovolemic thirst, which is typically caused by bleeding, sweating, or other types of fluid loss. Here, "thirst is based on low volume" (Kalat 307). The water you drink is being lost out of the tube. As such, it is not filling the necessary level of water within the body, causing hypovolemic thirst to induce the individual to want to drink even more. Thus, if you had a tube letting water out of your body, you would still remain thirsty and would drink even more to try to compensate.

Question 4

Some women crave salt during pregnancy because salt helps the body retain fluids. Pregnant women need to retain more water in order to help the progression of the pregnancy. Since sodium retains water, this may be a reason why some women crave salt during pregnancy. Moreover, in the first trimester, the levels of progesterone can increase the amount of sodium lost through urination. Then, pregnant women need to increase their salt intake in order to compensate for lower sodium levels in their bodies.