What is the chemical composition of the body? The smallest unit of a chemical element is an atom. Atoms contain electrons, neutrons and protons. We find out how these things act together to form chemical bonds, molecules and ionic compounds. Molecules do not always share equally when it comes to electrons. The molecule could be polar or non-polar, meaning does it have a positive and negative charge or is it just negatively charged. Water is the most abundant molecule in the body.
The unit also talks about how carbohydrates and lipids are similar. They both serve as a major source of energy in our bodies. Proteins are very important to our system and they perform a variety of very specific functions. Nucleic acids include DNA and RNA which are needed for genetic regulation. There was a lot of information in this unit.




Chemical Bonds: When two or more atoms share electrons to make a molecule. This bond is an attraction between opposite charges; so the positively charged protons in the nucleus are attracted to the negatively charge electrons orbiting the nucleus.

Covalent Bonds: When identical atoms share electrons their bond is the strongest because the negatively charged electrons are shared equally to positive charges of each nuclei. This is a nonpolar (molecule lacking + and - charges) covalent bond.

Ionic Bonds: This happens when the electrons are not shared at all but are transferred between two atoms. The atom losing its electron will become positively charged because the number of electrons is smaller than the number of protons. The atom which received the electron now has more electrons than protons so it is now negatively charged. Take note that when an atom or a molecule has either a positive or negative charge they are now called ions. The +ion is called a cation, because it will move toward the negative pole. The -ion is called an anion because it moves toward the positive pole. These two attract each other forming an ionic compound.

external image 3D_model_hydrogen_bonds_in_water.jpg
http://commons.wikimedia.org/wiki/File:3D_model_hydrogen_bonds_in_water.jpg

Hydrogen Bonds: When a hydrogen atom bonds with either oxygen or nitrogen it will have a slight positive charge because of the way it is pulled towards the other atom. It then has a weak attraction for any other atoms that may be near by. What is interesting, is that even with being weak, when everything is brought together the total forces are responsible for bending and folding long molecules of protein. These bonds are also responsible for holding a molecule of DHA together. Hydrogen bonds are also made by joining water molecules. This bond is responsible for many biological properties of water, including surface tension.






Carbohydrates and Lipids: Are similar with both consisting of atoms of carbon, hydrogen and oxygen. Both are major sources of energy in the body. There are several differences within their chemical structures and physical properties. These differences are going to affect how the molecules in the body function.

Carbohydrates are organic molecules which include simple sugars. Monosaccharides, like glucose, fructose and galactose, have the same ratio of atoms but are arranged in different ways. Disaccharides (double sugars) contain two monosaccharids, which share electrons. Sucrose (table sugar) is glucose and fructose. Lactose (milk sugar) is glucose and galactose and Maltose (malt sugar) which is two glucoses. When many monosaccharides or simple sugars are joined together the molecule becomes a polysaccharide.

This polysaccharide molecule is used to store energy. One polysaccharide stores thousands of glucoses. This is good because these larger molecules do not need to draw as much water into them. If all these molecules were separate monosaccharides, an excessive amount of water would need to be drawn into the cell which could damage or even kill it.

Lipids differ greatly in chemical structure of their molecules. The one thing that they all have in common is that they are insoluble in polar solvents such as water. Some of the lipids are triglycerides, phospholipids, steroids and prostaglandins.

Hydrocarbon chains and rings make up a triglyceride. The carbon and hydrogen are shared equally. One molecule of glycerol and three molecules of fatty acids are in a triglyceride. These can then be broken down into saturated fats or unsaturated fats. When the molecule is totally full of hydrogen on both sides of the carbon, it is saturated. When there are areas where the hydrogen is just on one side of the carbon and the carbons are double bonded together it is unsaturated.



Proteins: Shape is everything! There are 20 different amino acids that can be used to build a protein. They start as a chain and then are able to twist and bend because of the chemical interactions between the amino acids.
Proteins have a wide variety of functions in the body. They are used to develop tissue structure and help with the function of the tissues. Proteins are also in enzymes and antibodies that our bodies need and use. Proteins can also serve as receptors and carriers of molecules.

Here is a video regarding proteins that I though was fun to watch. please view.
http://www.youtube.com/embed/iaHHgEoa2c8

All information was taken from our book Human Physiology, 12th Edition, Stuart Ira Fox



With this chapter the talk of triglycerides really makes me want to crack down on my diet and exercise a few more minutes than what I am already doing. My triglycerides are elevated, not bad enough to be on any medicine but because of great family genes from my mother and father, I need to be monitoring it better.
I work in the clinic and see people getting their lab results. Their total cholesterol maybe ok but the LDL, HDL and triglycerides are not. They need to have some teaching from our dietician to really understand what is all involved with eating healthy. Another connection with elevated triglycerides is having an abnormal glucose level. If your blood sugars are elevated it can cause your triglycerides to be elevated also. Patients with an elevated fasting blood sugar will have a HGBA1C checked to get the average of what their blood sugar levels have been running for the last 3 months. Not everyone is diagnosed with diabetes but they certainly need to get a better handle on their eating habits.
Everyone has an excuse (me included) as to why they do not have enough time to exercise. I work for a doctor who is crazy about exercising. He has kept track and has not missed a day for the last 3 years. I think one of his motivations is to show others that yes you can make time and you will feel better.


Buffers are molecules and ions that are used to stabilize the pH of a solution when there have been changes in the hydrogen concentration. Blood pH normally does not decrease but remains constant at 7.40. This happens because of the action of bicarbonate ions. If the blood pH rises then carbonic acids will help buffer to stop the increase. These two, bicarbonate ions and carbonic acids, act as a buffer pair to keep the pH of blood from becoming acidic or alkaline.

Acidosis refers to an excess of acid in the blood that causes the pH to fall below 7.35. This could be caused by increased production of acid within the body, consumption of substances that are metabolized to acids, decreased in acid excretion or increase in excretion of bases. Alkalosis refers to an excess of base in the blood that causes the pH to rise above 7.45. This can happen from vomiting, dehydration or hyperventilating. Many conditions and diseases can interfere with blood pH. The lungs and the kidneys are involved in regulating the blood pH also. The lungs flush the acid out of the body by exhaling CO2. The kidneys excrete acids in the urine.

Enzymes are proteins that act as a catalyst. They increase the rate of a chemical reaction in the human body. Enzymes do not control the direction of the reaction. They are very specific and work to bind molecules together until the reaction can occur. There are hundreds of genetic diseases that result from a deficiency of a single enzyme. One is Phenylketonuria (PKU), which results from a deficiency of the enzyme phenylalanine hydroxylase. This converts the amino acid phenylalanine tyrosine. It causes mental retardation due to defective formulation of myelin. PKU can be detected at birth by a screening test for phenylalanine in the blood. Clinical symptoms can be avoided by keeping to a strict low phenylalanine diet.

Information from our textbook Human Physiology, 12th Edition, Stuart Ira Fox. WebMD, Encyclopedia & Dictionary of Medicine, Nursing & Allied Health, 5th Edition