Major Muscles of the Body_Functions

Nutrition, Metabolism, and Body Temperature Regulation. Nutrient is a substance that promotes normal growth, maintenance, and repair. Major nutrients are carbohydrates, lipids, and proteins. Other nutrients include vitamins and minerals (and technically speaking, water).Complex carbohydrates (starches) are found in bread, cereal, flour, pasta, nuts, and potatoes .Simple carbohydrates (sugars) are found in soft drinks, candy, fruit, and ice cream.Glucose is the molecule ultimately used by body cells to make ATP.Neurons and RBCs rely almost entirely upon glucose to supply their energy needs.Excess glucose is converted to glycogen or fat and stored .The most abundant dietary lipids, triglycerides, are found in both animal and plant foods.Essential fatty acids – linoleic and linolenic acid, found in most vegetables, must be ingested. Dietary fats help the body to absorb vitamins, a major energy fuel of hepatocytes and skeletal muscle, and a component of myelin sheaths and all cell membranes. Lipids functions in smooth muscle contraction, control of blood pressure and inflammation. Cholesterol stabilizes membranes and is a precursor of bile salts and steroid hormones. The dietary requirements for lipids are higher for infants and children than for adults. The American Heart Association suggests that fats should represent less than 30% of one’s total caloric intake, saturated fats should be limited to 10% or less of one’s total fat intake, and daily cholesterol intake should not exceed 200 mg. Complete proteins that meet all the body’s amino acid needs are found in eggs, milk, milk products, meat, and fish.Incomplete proteins are found in legumes, nuts, seeds, grains, and vegetables. Essential amino acids are the building blocks for nonessential amino acids. Protein supply for nonprotein nitrogen-containing substances. Daily intake should be approximately 0.8g/kg of body weight. All amino acids needed must be present at the same time for protein synthesis to occur. Protein will be used as fuel if there is insufficient carbohydrate or fat available. The rate of protein synthesis equals the rate of breakdown and loss. Anabolic hormones accelerate protein synthesis. Vitamins are organic compounds needed for growth and good health. They are crucial in helping the body use nutrients and often function as coenzymes. Only vitamins D, K, and B are synthesized in the body; all others must be ingested. Water-soluble vitamins (B-complex and C) are absorbed in the gastrointestinal tract . Vitamin B12 additionally requires gastric intrinsic factor to be absorbed. Fat-soluble vitamins (A, D, E, and K) bind to ingested lipids and are absorbed with their digestion products. Vitamins A, C, and E also act in an antioxidant cascade. There are seven minerals are required in moderate amounts . These are calcium, phosphorus, potassium, sulfur, sodium, chloride, and magnesium. Dozens are required in trace amounts. Minerals work with nutrients to ensure proper body functioning. Calcium, phosphorus, and magnesium salts harden bone.

A Brief History of Washington’s Crossing of the Delaware River, Christmas Night 1776... In the fall of 1776, General George Washington and his army had suffered a series of defeats at the hands of the British Army. The Continental Army had lost every battle with the British in the New York campaign: Long Island, Manhattan, Brooklyn Heights, Harlem and White Plains and had surrendered Fort Washington and Fort Lee. At Fort Lee, the army barely escaped and was forced to leave behind its store of provisions, ammunition, and many of its weapons. A sense of defeat had settled around Washington as he was forced to retreat across New Jersey in November and finally to Pennsylvania on December 8, 1776. The British, at least, considered the war over. By December 11th, the only reason the British had not taken Philadelphia, the seat of the Continental Congress, was that Washington had ordered every boat in the Delaware River on the New Jersey side to be brought to the Pennsylvania side, thus denying the British army transportation. Washington knew that the British would be capable of resuming an offensive by crossing the Delaware once it iced over. As the harsh winter set in, the morale of the American troops was at an all-time low. The soldiers were forced to deal with a lack of both food and warm clothing, while Washington watched his army shrink because of desertions and expiring enlistments. Now, more than ever, a victory was desperately needed. Washington devised a courageous plan to take the offensive and cross the Delaware River on Christmas night and attack the Hessian garrison at Trenton, New Jersey, nine miles south of his encampment near McConkey's Ferry. The original plan called for three divisions to cross the Delaware under the cover of darkness. Lt. Col. John Cadwalader's division was to cross at Bristol and engage the southern most contingent of British forces — Hessian troops under the command of Colonel von Donop. General James Ewing's division was to cross at Trenton Ferry and take a position south of Assunpink Creek below Trenton and hold the bridge over that stream. Washington's division was to cross at McConkey's Ferry and then divide into two corps under General Nathanael Greene and General John Sullivan. Their point of attack was Trenton and the Hessian troops quartered there under the command of Colonel Johann Gottlieb Rall. The boats to be used for the crossing were gathered earlier in the month in compliance with General Washington's orders, primarily as a defensive measure. Various types of boats had been collected, most notably the large Durham boats used to carry pig iron down the Delaware to the Philadelphia markets. There were a number of problems in moving a large number of men, cannons, and supplies in an age when overland transportation was by foot and animal power. The roads were rutted and winding. There were no bridges over major rivers because the technology did not exist to span great distances. A river like the Delaware was crossed by ferry, sometimes out of service because of ice floes or floods, and certainly not designed to carry masses of men and equipment across quickly. A river could be a formidable natural barrier to an army on the move. Washington had several logistical concerns for the crossing. In addition to the troops were the cannon; each of which required at least two horses to pull it. The heavier twelve pounders, and probably the eight pounders, had four horses. There would have been between four and six ammunitions wagons. Officers of the rank of colonel or higher may have had horses. In sum, Washington had to move 2,400 men, eighteen cannons, at least four ammunition wagons and fifty to seventy-five horses across the Delaware River the night of December 25, 1776. Fully expecting to be supported by Cadwalader's and Ewing's divisions south of Trenton, Washington assembled his own troops near McKonkey's Ferry in preparation for the crossing. By 6:00 pm, 2,400 men had begun crossing the ice-chocked river. There was an abrupt change in the weather, forcing the men to fight their way through sleet and a blinding snowstorm. The river was flooded with sheets of ice moving at eleven or twelve miles per hour. These obstacles proved to be too much for the two supporting divisions led by Generals Cadwalader and Ewing, who did not cross at their assigned points along the river. It was Washington's pure force of will and determination that led to his troops' successful crossing of the river. Increasing Washington's odds were the sailors of Marblehead, Massachusetts. This group of hardened seamen, led by Col. John Glover, were used to the Nor'easters of New England. Sheer determination and muscles conditioned to the demands of rowing under the weather conditions now facing the Continental army enabled the Marbleheaders to row back and forth across the Delaware countless times. During the time of the Revolution, American soldiers marched single file along the margins of the roads. They were only assembled into a battle line (three deep) when they reached the battlefield. The battle plan had Washington's army marching in two divisions... General Greene's and General Sullivan's. They made a night march in two columns on separate roads, a very tricky operation that was prone to failure since the columns needed to arrive at the battlefield at the same time to carry out the surprise attack planned by Washington. The American army carried out the march flawlessly. Against all odds, Washington and his men successfully completed the crossing and marched to Trenton on the morning of December 26th and, in the resulting battle, achieved a resounding victory over the Hessians. By moving ahead with his bold and daring plan, General Washington reignited the cause of freedom and gave new life to the American Revolution.

1. SA node sends an impulse causing the atria to contract 2. Blood moves from the right atrium into the right ventricle past the tricuspid valve 3. Blood moves from the left atrium into the left ventricle past the mitral or bicuspid valve 4. Impulse pauses at AV node to allow for maximum blood to be squeezed into the ventricles 5. Impulse travels to the AV bundle (or bundle of His) and down the bundle branches 6. Impulse travels out Purkinje fibers causing the apex to contract 7. The apex contraction increases the blood pressure in the ventricles causing the Mitral and Tricuspid (AV) valves to close. 8. Atria repolarize and begin to fill 9. Purkinje fibers cause the ventricle walls and papillary muscles to depolarize (contract) 10. Papillary muscles hold the AV valves shut (keep them from prolapsing) through the chordae tendineae connection 11. The aortic and pulmonary semilunar valves open when the pressure is higher in the ventricles than in the major arteries 12. Blood moves from right ventricle to pulmonary trunk/arteries past the pulmonary semilunar valve 13. Blood moves from left ventricle to aorta past the aortic semilunar valve 14. Blood pathway is arteries to arterioles, to capillaries (or capillary bed), to venules, veins and vena cava back to the right atrium 15. The ventricles start to repolarize (relax) which decreases the pressure in the ventricles 16. When the pressure is lower in the ventricles than in the major arteries, blood moves back toward heart shutting semilunar valves 17. When the aortic valve closes, the openings to the coronary arteries are exposed 18. Back pressure in the aorta pushes blood out the left and right coronary arteries supplying the heart with oxygenated blood 19. The AV valves open and blood moves from the atria into the ventricles when the ventricular pressure falls below atrial pressure. 20. The process starts again when the SA node fires causing the atria to contract.

The endoplasmic reticulum (EN-doh-PLAZ-mik ri-TIK-yuh-luhm), abbre- viated ER, is a system of membranous tubes and sacs, called cisternae (sis-TUHR-nee). The ER functions primarily as an intracellu- lar highway, a path along which molecules move from one part of the cell to another. The amount of ER inside a cell fluctuates, depending on the cell’s activity. There are two types of ER: rough and smooth. The two types of ER are thought to be continuous. Rough Endoplasmic Reticulum The rough endoplasmic reticulum is a system of interconnected, flattened sacs covered with ribosomes, as shown in Figure 4-15. The rough ER produces phospholipids and proteins. Certain types of proteins are made on the rough ER’s ribosomes. These proteins are later exported from the cell or inserted into one of the cell’s own membranes. For example, ribosomes on the rough ER make digestive enzymes, which accumulate inside the endoplasmic retic- ulum. Little sacs or vesicles then pinch off from the ends of the rough ER and store the digestive enzymes until they are released from the cell. Rough ER is most abundant in cells that produce large amounts of protein for export, such as cells in digestive glands and antibody-producing cells. Smooth Endoplasmic Reticulum The smooth ER lacks ribosomes and thus has a smooth appear- ance. Most cells contain very little smooth ER. Smooth ER builds lipids such as cholesterol. In the ovaries and testes, smooth ER produces the steroid hormones estrogen and testosterone. In skeletal and heart muscle cells, smooth ER releases calcium, which stimulates contraction. Smooth ER is also abundant in liver and kidney cells, where it helps detoxify drugs and poisons. Long-term abuse of alcohol and other drugs causes these cells to produce more smooth ER. Increased amounts of smooth ER in liver cells is one of the factors that can lead to drug tolerance. As Figure 4-15 shows, rough ER and smooth ER form an interconnected network. Copyright © by Holt, Rinehart and Winston. All rights reserved. reticulum from the Latin rete, meaning “net”; reticulum means “little net” Word Roots and Origins The endoplasmic reticulum (ER) serves as a site of synthesis for proteins, lipids, and other materials. The dark lines in the photo represent the membranes of the ER, and the narrow lighter areas between the dark lines show the channels and spaces (cisternae) inside the ER. FIGURE 4-15 Smooth ER Ribosomes Rough ER Cisternae 82 CHAPTER 4 GOLGI APPARATUS The Golgi apparatus, shown in Figure 4-16, is another system of flattened, membranous sacs. The sacs nearest the nucleus receive vesicles from the ER containing newly made proteins or lipids. Vesicles travel from one part of the Golgi apparatus to the next and transport substances as they go. The stacked membranes modify the vesicle contents as they move along. The proteins get “address labels” that direct them to various other parts of the cell. During this modification, the Golgi apparatus can add carbohydrate labels to proteins or alter new lipids in various ways. VESICLES Cells contain several types of vesicles, which perform various roles. Vesicles are small, spherically shaped sacs that are surrounded by a single membrane and that are classified by their contents. Vesicles often migrate to and merge with the plasma membrane. As they do, they release their contents to the outside of the cell. Lysosomes Lysosomes (LIE-suh-SOHMZ) are vesicles that bud from the Golgi appa- ratus and that contain digestive enzymes. These enzymes can break down large molecules, such as proteins, nucleic acids, car- bohydrates, and phospholipids. In the liver, lysosomes break down glycogen in order to release glucose into the bloodstream. Certain white blood cells use lysosomes to break down bacteria. Within a cell, lysosomes digest worn-out organelles in a process called autophagy (aw-TAHF-uh-jee). Lysosomes are also responsible for breaking down cells when it is time for the cells to die. The digestion of damaged or extra cells by the enzymes of their own lysosomes is called autolysis (aw-TAHL-uh-sis). Lysosomes play a very important role in maintaining an organism’s health by destroying cells that are no longer functioning properly. Copyright © by Holt, Rinehart and Winston. All rights reserved. The Golgi apparatus modifies many cellular products and prepares them for export. FIGURE 4-16 CELL STRUCTURE AND FUNCTION 83 Peroxisomes Peroxisomes are similar to lysosomes but contain different enzymes and are not produced by the Golgi apparatus. Peroxisomes are abundant in liver and kidney cells, where they neutralize free radicals (oxygen ions that can damage cells) and detoxify alcohol and other drugs. Peroxisomes are named for the hydrogen peroxide, H2O2, they produce when breaking down alco- hol and killing bacteria. Peroxisomes also break down fatty acids, which the mitochondria can then use as an energy source. Other Vesicles Specialized peroxisomes, called glyoxysomes, can be found in the seeds of some plants. They break down stored fats to provide energy for the developing plant embryo. Some cells engulf material by surrounding it with plasma membrane. The resulting pocket buds off to become a vesicle inside the cell. This vesicle is called an endosome. Lysosomes fuse with endosomes and digest the engulfed material. Food vacuoles are vesicles that store nutrients for a cell. Contractile vacuoles are vesicles that can contract and dispose of excess water inside a cell. Protein Synthesis One of the major functions of a cell is the production of protein. The path some proteins take from synthesis to export can be seen in Figure 4-17. In step , proteins are assembled by ribosomes on the rough ER. Then, in step , vesicles transport proteins to the Golgi apparatus. In step , the Golgi modifies proteins and pack- ages them in new vesicles. In step , vesicles release proteins that have destinations outside the cell. In step , vesicles containing enzymes remain inside the cell as lysosomes, peroxisomes, endo- somes, or other types of vesicles. 5 4 3 2 1 Copyright © by Holt, Rinehart and Winston. All rights reserved. Proteins are assembled by ribosomes on the rough ER. Vesicles carry proteins from the rough ER to the Golgi apparatus. Proteins are modified in the Golgi apparatus and enter new vesicles. Some vesicles release their proteins outside the cell. Other vesicles remain in the cell and become lysosomes and other vesicles. Nucleus

Major Muscle Groups

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