After reading up about Homeostasis in humans, I am able to link how humans regulate temperature, glucose and water to our OBS experience.
Regulation of Glucose in Humans
Before reading up, I thought that there will be a way that the body regulates glucose when we have excess glucose in our blood, which is after we eat, and when we have too little glucose in our blood, which is when we are doing vigorous activities.
After reading up, I realised that this is how to body regulates our blood glucose concentration:
After we eat a meal, our blood glucose concentration will rise above normal. In other words, there will be too much glucose in our blood. Thus the Islets of Langerhans in the pancreas are stimulated, causing the pancreas to secret more insulin. Insulin increases the permeability of the cell membrane to glucose. Hence, glucose is absorbed more quickly by the cells and the insulin causes the liver to convert glucose into glycogen, which is then stored in the liver and muscles. Hence, both insulin production and blood glucose concentration decreases.
Conversely, during vigorous muscular contraction, our blood glucose concentration will fall below normal. This also stimulates the islets of Langerhans in the pancreas as there is too little glucose in the blood. Thus, the islets of Langerhans are stimulated to secrete a glucagon into the bloodstream. Glucagon is transported to the liver and muscles and causes the conversion of stored glycogen back into glucose. The glucose then enters the bloodstream, causing our blood glucose concentration to increase.
This regulation of glucose in humans is applicable our OBS days as when we eat food, there will be excess glucose which will be stored in the liver and muscles. Thus glucose will sustain us throughout the strenuous activities such as trekking, rock-climbing and canoeing during OBS. When there is a lack of glucose in our blood, glucagon is produced to convert the glycogen in glucose, which then enters our bloodstream to raise the blood glucose concentration. This gives us the energy to continue on our activities.
Regulation of Water
Before reading up, I knew that when we drink more water, the amount of water in our blood increases, which causes us to produce more dilute urine, which we excrete out from our body, to maintain the water potential in our blood. On the other hand, when we are dehydrated or when we sweat a lot, we have less water in our blood, which causes less urine to be produced.
After reading up, I learnt that when we drink a large amount of water, water potential of our blood increases. Less water is reabsorbed by our kidney tubules as less antidiuretic hormone (ADH) is released by the pituitary gland. Thus more water is excreted in the form of more dilute urine. Conversely, when the water potential of our blood is low, more ADH is released by the pituitary gland, causing more water to be reabsorbed by the kindey tubules. Less water is excreted; hence, less urine is produced. This causes our blood's water potential to increase.
Hence, during OBS, when we drink a lot of water o hydrate ourselves during OBS, we will have the tendency of needed to excrete urine. When we sweat a lot due to the vigorous activities or if we do not drink enough water, we have less urine to excrete.
Regulation of Temperature
Before reading up, I know that when we gain heat, there is be a rise in our blood temperature. To maintain a constant body temperature, we produce sweat which causing more latent heat of vaporisation is removed from our body. Moreover, we breathe rapidly, which also helps to remove heat. This is why during OBS, when we are constantly under the sun, we sweat a lot and and during vigorous activities, we tend to breathe heavily and rapidly as all these are ways our body loses heat to ensure that our body temperature is regulated.
After reading up, I realised that there were other ways that our body uses to regulate our body temperature during OBS.
- Our arterioles dialate to allow more blood to flow through the blood capillaries in our skin. Hence, more heat is lost through our skin by radiation, convection and conduction.
- The shunt vessels in certain parts of our skin constrict to allow more blood to enter our capillaries, increasing heat loss
- The metabolic rate of our body slows down, thus less heat is produced within our body.
