Q.+METABOLISM

=METABOLISM =



http://www.nlm.nih.gov/medlineplus/ency/imagepages/9624.htm

__OVERVIEW __ Metabolism is defined as all of the chemical reactions in the body. These reactions include those that result in energy storage (anabolism) and those that result in energy liberation (catabolism). I generally think of metabolism in the aspect of losing or gaining weight. Of course as women we are always worried about our weight, but ‘metabolism’ goes a little deeper than just this issue. In this chapter we learned more about nutritional requirements and how the body metabolizes nutrients. The chapter also covers the regulation of energy metabolism and how hormones regulate the metabolism.



Food provides the energy needed for cell respiration. Out metabolic rate is measured by the amount of heat generated or by the amount of oxygen consumed by the body. Physical activity, temperature and eating influence the metabolic rate, and the basal metabolic rate is influenced by the rate of oxygen consumption. BMR is strongly influenced by thyroid secretion, but is primarily determined by an individual’s age, sex and body surface area. Differences in energy requirements are due to the differences in physical activity. An increase in physical activity will require higher energy expenditures. When we eat more than the body needs for energy, the excess calories are stored as fat, where weight may be lost when our calorie intake is less than the energy required for cell respiration. All in all we have to get out butts moving and eat less ‘energy’ than our body needs to sustain life. (Ok, I’ll start Monday!) Food also supplies the body with the materials needed for synthesis reactions that constantly occur in the body. This is anabolism. It includes synthesis of DNA and RNA, protein, glycogen, triglycerides and polymers. These reactions occur to replace molecules that are broken down into smaller components (monomers). Break down of molecules and the reactions of cell respiration that breakdown monomers to CO and H2O are referred to as catabolism.

Fatty acids, amino acids and other molecules are used by the body tissues for cell respiration. Molecules that are used can come from the energy reserves of glycogen, fat or protein. The glycogen and fat act as energy reserves where proteins are considered a secondary or emergency function. Body protein provides amino acids for energy; however it can only do this by the breakdown of proteins needed for functions such as muscle contraction, structural strength, or enzymatic activity. Cell respiration uses energy that is provided by the products of digestion that are absorbed in the small intestine. Glucose and fatty acids that are carried by the blood are referred to as circulating energy substrates.

Absorption of energy carriers from the intestine rises to high levels over a four hour period after eating a meal (absorptive state). The levels lower to zero between meals and after the absorptive state has ended (postabsorptive or fasting state). Although these levels fluctuate, plasma glucose and other energy substrates do not reflect the levels of energy. Digestion products are removed from the blood and deposited as energy reserves. This enables the body to have adequate concentrations of energy to sustain metabolism at all times. The rate at which the energy substrates are used is controlled by hormones. Antagonistic effects of insulin, glucagon, growth hormone, thyroxine and other hormones aid in the balance between anabolism and catabolism. Concentrations of glucose regulate the secretion of insulin and glucagon. The concentrations rise during the absorption of a meal and fall between meals. The changes in the secretion of insulin and glucagon at these times help maintain homeostasis of plasma glucose levels. Inadequate secretion of insulin can result in hyperglycemia. Hyperglycemia is characteristic of Diabetes Mellitus and occurs from insufficient secretion of insulin or the inability of secreted insulin to stimulate cellular uptake of glucose. There are two forms of DM, Type 1 and Type 2. In Type 1 (insulin-dependent) diabetes beta cells of the islets of Langerhans are destroyed and secrete little to no insulin. In Type 2 (non insulin-dependent) the tissue responsiveness to insulin is decreased to the target tissues. Diabetes is the major cause of kidney failure as well as limb amputation from decreased circulation. It is also the second leading cause of blindness. Type 2 diabetes which is associated with metabolic syndrome (high blood triglycerides and low HDL) there is an increased risk of atherosclerosis contributing to heart disease and stroke.



Metabolism is also regulated by adrenal hormones, thyroxine and growth hormone. They stimulate the catabolism of carbohydrates and lipids. Thyroxine and growth hormone also promote protein synthesis, body growth and development of the CNS. The adrenal medulla of the adrenal gland secretes catecholamines and the adrenal cortex secretes corticosteroid hormones. Catecholamines that are released by the adrenal medulla stimulate glycogenesis and release of glucose from the liver along with lipolysis and release of fatty acids from adipose tissue. Glucocorticoids are secreted by the adrenal cortex in response to ACTH secretion from the anterior pituitary. This is a general adaptation syndrome related to stress! The increased secretion of glucocorticoids during fasting or exercise supports the effects of increased glucagon and decreases of insulin secretion. Thyroid follicles secrete thyroxin as a response to TSH secretion from the anterior pituitary. Thyroxin (T4) which is converted into triiodothyronine (T3) regulates the rate of cell respiration and aids in proper growth and development. Growth hormone stimulates growth in children and adolescents. The secretion of growth hormone is controlled by a releasing and inhibiting hormone from the hypothalamus. It is stimulated by an increase in the concentrations of amino acids in the plasma and a decrease of plasma glucose levels.



LJ Fox, Stuart Ira. (2009). //Human Physiology//. New York, NY: McGraw-Hill.

__ESSENTIAL QUESTIONS __

**Find a product that says that it will boost your metabolism. Research the physiology behind how it boosts a person's metabolism.** Product: **Triple Complex Slimmer's Assist™** The company claims "Homeopathic remedy improves sluggish digestion, boosts metabolism & increases weight loss" Triple Complex Slimmer's Assist contains the following 100% homeopathic ingredients:
 * **Calc phos** (6X) supports healthy digestion at a cellular level. It also assists in the formation of new blood cells and is present in connective tissue and digestive juices making it a vital component of the body's nutrition process from digestion and assimilation through to energy expenditure. An excellent general tonic for all ages!

The skeleton stores calcium and phophate in the form of crystals known as hydroxyapatite. The calcium phosphate in the hydroxyapatite crystals comes from the action of osteoblasts. Osteoblasts secrete a matrix which is hardened by deposits of hydroxyapatite in a process called bone deposition. Bone resorption then is the dissolution of hydroxyapatite produced by ostoclasts returning the bone calcium and phosphate to the blood. Ostoclasts produce a surface receptor protein known as RANK. Osteoblasts form the ligand for the RANK receptor known as the RANK ligand or RANKL which binds to RANK and stimulates osteoclast development and activation.Osteoblasts also secrete osteoprotegerin which interferes RANKL to bind to RANK. Bone resorption begins when osteoclasts attach to the bone matrix and the osteoclast must secrete products that dissolve calcium phosphate and digest the proteins of the bone matrix. The formation and resorption of bone occurs constantly. Ultimately the plasma concentration of calcium and phosphate are maintained by hormonal control of the intestinal absorption and urinary excretion of them. The maintenance of normal plasma calcium concentrations in important because calcium does so much in our bodies. Calcium is needed for blood clotting and cell signaling functions. The cell signaling includes calcium as a second messenger of hormone action, a signal for neurotransmitter release from axons due to action potentials, and stimulus for muscle contraction in response to electrical excitation. Calcium is also important to maintain proper membrane permeability. Low plasma calcium concentration increases the permeability of cell membranes to NA+ and other ions. So calcium phosphate would help increase metabolism by having the proper level of calcium and phosphate your muscles will be working more efficiently, including peristalsis of digestion and regular muscular contractions. If the body is working at optimal performance and has the calcium and phosphate in levels that it needs it will boost metabolism and help with possible weight loss.

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**Why do crash diets not work on a physiology level?** The reason crash diets do not work on a physiological level is because most crash diets cut certain foods or nutrients out of your diet. In the short term this will encourage the body to use the nutrients it has at an extraordinary rate. This will help with short term weight loss. However in the long term the body cannot function optimally without a well balanced diet and all of the nutrients that it needs for it to function properly. When the body is not receiving proper nutrients the BMR will be lower than when eating the proper nourishment or just above what is required to maintain BMR. So when people go on crash diets their BMR is lowered making it harder to lose weight and when the quit following the diet, their metabolism does not return to normal and weight is gained back faster than pre-diet because the body has adjusted its calorie expenditure to compensate for the shortage.

__SUMMARY __

**What is metabolism? Compare and contrast anabolism and catabolism.** **What are enzymes and what role do they play in metabolism?** **What is basal metabolic rate (BMR)?**

Our bodies require energy for everything we do. The cells in our bodies converts the food we eat into vital energy. If there is no metabolism going on in our bodies we would not be able to survive. Our metabolism comes from the plants that we consume. The plants first must get their energy from the sun by a process called photosynthesis in which the plant is able to turn sunlight into energy by using carbon dioxide and water along with the suns energy and cholorophyll, the green color of the plant. We get our plant energy by either eating the plant itself or by eating meat from an animal that has eaten plants. This plant energy comes into our bodies in the form of sugar. No that the body has the sugar in it we must break down the sugar in order for it to be used as energy. Anabolism is a constructive form of metabolism because it helps to make new cells, make sure the body tissues stay in good health, and keep some energy in storage for when we need it in the future. When anabolism occurs, there are small molecules that are turned into carbohydrates, lipids or fats, and proteins, which are all much larger proteins than the starting ones. Catabolism metabolism is the driving force behind anabolism. Catabolism provides all the engery need to keep the cells in our bodies moving, provides body heat, and allows our muscles to move and fuction properly. This all happens by the carbohydrates and lipids or fats be broken down into small molecules so that anabolism can occur. Catabolism also leaves behind some waste products. The skin, lungs, kidneys and intestines are the organs that are responsible for riding the body of the waste products. There are enzymes found in your digestive tract that help to break down carbs into simple sugars such as glucose, fat into fatty acids, and proteins into amino acids. All three of these products can then be used for engery if the body needs it. They are also transported into the cells after being absorbed into the blood stream. There are additional enzymes found in the cells that will help with speeding up the metabolism of these or regulated the metabolism. The engery released from the metabolizing of these products can either be used for energy right away or the energy can be stored in the liver, body fat, muscles, or tissues. The endrocrine hormones that come from the thyroid play a huge role in how fast or how slow a persons metabolism is. The endocrine hormones that come from the pancrease play a role in what type of metabolism will occur, anabolic or metabolic. If a person consumes too many calories that the body can use right away the body will store it. When there is too many calories to be stored that is when people will start to gain weight. There are three factors that affect how quickly someone will burn calories, how much exercise they take part in, what their fat content is, and what their basal metabolic rate (BMR) is. Your BMR is how fast your body can burn energy it gets from calories at rest. Your BMR can tell you how fast you might gain weight. Even though your BMR is somewhat inherited you are still able to change it. Exercise is a good way to heighten your BMR. The more muscle and less fat that you have, the higher your BMR will be.

__APPLICATION __

**What is your BMR?****BMR calculator** **Jessica BMR of 1771.8** **BMR Info used for calculation** **Height 5ft 4 in** **Weight 220lbs** **Age 30****Female** **Figure out your Daily Calorie Needs.****calorie calculator** **Jessica Daily Calorie Needs is 1750** **Age 30** **Height 5ft 4 in** **Weight 220 lbs** **Activity Level Inactive****Female** **What are things you can do to increase your BMR and why?** For Jessica (me) exercise is a good way to heighten my BMR because the more muscle and less fat a person has, the higher your BMR will be, and since I am a fairly inactive person increasing my exercise would be a positive way to increase my BMR.

Pamela's BMR : 1451.65 BMR info. used for calculation: Height: 5 ft 6in Weight: 145lbs Age: 27 Sex: Female

Pamela's daily caloric needs: 1996 calories Age: 27 Height: 5ft 6tin Weight: 145lbs Activity Level: Light activity Sex: Female

To increase my Basal Metabolic Rate (BMR), I could eat healthier foods such as fruits and vegetables and cut back on my intake of meats, fats, and empty calorie foods. I could also eat more smaller meals instead of three big meals throughout the day, and of course exercise daily. Exercising daily at a moderate speed of 4.5 to 5 mph on a treadmill will allow me to burn fats and also build lean body mass, therefore increase my metabolic rate and decreasing my weight.

Lorey's BMR: 1510.95 BMR info used for calculations: Ht: 5 ft 2 in Wt: 173 lbs Age: 40 Sex: Female

Calories per day to maintain weight: 2078 Activity Level: Light Activity

Calories per day to lose weight: 1662

To increase my metabolic rate I can increase my exercise regime (which is pretty sad now!) I really should eat breakfast, but with working nights, my eating habits are pretty screwed up. I should eat several small meals a day so that my body is working more to digest foods which will increase my metabolism. I am already in the mindset of not eating until I feel sick so eating more meals a day shouldn't be a problem. Also getting rid of or consuming less soda pop and junk food would go a long way. My weight has been pretty stable within 10-15 pounds in the last 3 years so in reality, getting my butt moving would be the best thing for me!!!

Amanda's BMR: 1779.57 BMR infor used for calculations: Ht: 5 ft 9in Wt. 213 Age:25 Sex: F

Calories per day to maintain weight: 2444 cal/day. Calories per day to lose weight: 1955 cal/day.

I can start exercising routinely because I usually start out good then end up quitting. I could consume less soda and junk food. I can consume less fast food. I should also consume smaller portions at meals.

Jill's BMR : 2061 BMR info. used for calculation: Height: 5 ft 7in Weight: 280 lbs Age: 27 Sex: Female

Jill's daily caloric needs: 2050 calories Age: 27 Height: 5ft 7in Weight: 280 lbs Activity Level: Inactive Currently due to Pregnancy Sex: Female

In order to increase my BMR after I have my baby would be to start a regular exercise program. Increasing my activity and also eating a more balanced diet of smaller more frequent meals would be a great start to increasing my BMR and in general just be healthier.