In this unit, we established the difference between digestion in absorption. Digestion involves the breakdown of food these nutrients, while absorption involves the body's physical reception of these nutrients. In digestion, organs are separated into two main groups: the alimentary canal and the accessory digestive organs. Absorption involves the small intestine, the liver, and the large intestine.
The digestive system, which contains the alimentary canal, performs many basic functions including ingestion, secretion, propulsion, digestion, absorption, and defecation. The stomach provides a physical and chemical change in which proteins break down. The small intestine has 3 parts: the duodenum, jejunum, and the ileum. In the large intestine, food passes through the large intestines: cecum, appendix, ascending colon, transverse colon, descending colon, sigmord colon, rectum, and anus.
Diabetes has become more prevalent in our modern day society. Insulin is the hormone produced by the beta cells of the pancreas and is involved in the stimulation of glycogen synthesis. It is the key which unlocks cells allowing glucose to enter. Glucose is transported into muscle and fat cells by glucose transporter GLUT 4. In the presence of insulin, GLUT 4 travels to the plasma membrane. In Type 1, blood glucose levels are sensitive to small changes in diet. In Type 2 diabetes, the body does not react to insulin properly.
Fuel metabolism is an essential part of how we function in our daily lives. There are 3 stages of energy extraction: the large molecules are broken down, small molecules are turned into Acetyl CoA, and common pathways in oxidation of fuel molecules. The fed state, or absorptive state occurs directly after a meal. The fasting state occurs within one hour of a meal. A ketone body is produced from Acetyl CoA by the liver. The Cori cycle occurs during exercise, as muscles must rely on glycolysis for ATP, consequently producing lactic acid.
In our "Stress Metabolism, and Liquidating Your Assets" article, I learned that stress can affect appetite in a huge way. AcTH stimulates appetite while CRH represses it. When a stressful event occurs, there is a burst of CRH secretion. It takes many minutes to see a surge in glucocorticoid levels in the blood stream. CRH makes its effects clear in seconds while glucocorticoids take minutes to hours. When the stressor is released, CRH takes seconds to clear while glucocorticoids take hours to clear.
The endocrine system controls the processes involved in movement and physiological equilibrium. Steroid hormones are lipid soluble and diffuse through the cell membrane. Nonsteroid hormones are not lipid soluble and are received by receptors external to the cell membrane. The pituitary gland is controlled by the hypothalamus or other neural mechanisms. The thyroid gland regulates metabolism and increases protein synthesis. The parathyroid glands regulate phosphate levels.
Finally, the lymphatic system functions as a fluid recovery gutter by returning fluid to the bloodstream. Lymph flows within lymphatic vessels and is similar to plasma. A large number of T cells develop in the thymus, while the lymph nodes filter lymph trapping foreign substances, then destroyed by immune cells. The spleen is the largest lymphoid organ and contains both red pulp[ and white pulp.
In terms of my New Years resolution, I have been able to get more sleep, just because I'm better at managing my time as a second semester senior. I plan to sleep even earlier by setting an alarm to remind myself to sleep, even when I don't feel especially tired. In terms of my Anatomy goals, I have been able to adhere to those as well. Everyday before bed, I have been reviewing my notes, which allows me to do better on my temp checks. My next step is to begin reviewing earlier, which would enable me to sleep earlier as well.
