1. Pima Medical Institute BIO 120
Hole’s Essentials of Human Anatomy & Physiology
Acids, Bases, and Chemicals
BIO 120 Anatomy & Physiology
Lesson 2
David Shier, Jackie Butler, Ricki Lewis, Hole’s Essentials of Human Anatomy & Physiology, 10th Ed. CopyrightThe McGraw-Hill Companies, Inc. Created by Dr. Melissa Eisenhauer, Trevecca Nazarene University

2. F. Acids and Bases:
1. Substances that release ions in water are called electrolytes.
2. Electrolytes that release hydrogen ions in water are called acids.
3. Electrolytes that release ions that combine with hydrogen ions in water are called bases.
When ionically bound substances dissolve in water, the slightly negative and positive ends of the water molecules cause the ions to leave each other and interact with the water molecules instead. In this way, the polarity of water dissociates salts in the internal environment (see Figure 2.10, slide 26). For example, sodium chloride (NaCl) release sodium ions (Na+) and chloride ions (Cl-) when it dissolves: NaCl — Na+ + Cl-
Since the resulting solution contains electrically charged particles (ions), it will conduct an electric current. Substances that release ions in water are, therefore, called electrolytes.
Acids are electrolytes that release hydrogen ions (H+) in water. For example, in water, the compound hydrochloric acid (HCl) releases hydrogen ions (H+) and chloride ions (Cl-): HCL — H+ + Cl-
Electrolytes that release ions that bond with hydrogen ions are called bases. For example, the compound sodium hydroxide (NaOH) release hydroxide ions (OH-) when placed in water: NaOH — Na+ + OH-
The hydroxide ions, in turn, can bond with hydrogen ions to form water; thus, sodium hydroxide is a base.

3. The polarity of water dissociates salts
The polar nature of water molecules dissociates sodium chloride (NaCl0 in water, releasing sodium ions (Na+) and chloride ions (Cl).

4. F. Acids and Bases: (continued)
4. The concentrations of H+ and OH- in the body is very important to physiology.
5. pH represents the concentration of hydrogen ions [H+] in solution.
The concentrations of hydrogen ions (H+) and hydroxide ions (OH-) in body fluids greatly affect the chemical reactions that control certain physiological functions, such as blood pressure and breathing rate. Since their concentrations are inversely related (if one goes up, the other goes down), we need to keep track of only one of them. A value called pH measure hydrogen ion concentration.

5. CopyrightThe McGraw-Hill Companies, Inc
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
6. A pH of 7 indicates a neutral solution with equal numbers of hydrogen ions and hydroxyl (OH-) ions.
a. A pH of zero to less than indicates the presence of more hydrogen ions, and thus the solution is more acidic; a pH greater than 7 to 14 indicates more hydroxyl ions, or a basic
(alkaline) solution.
b. Between each whole number of the pH scale there is a tenfold difference in hydrogen ion concentration.
The pH scale ranges from 0 to 14. a solution with a pH of 7.0, the midpoint of the scale, contains equal numbers of hydrogen and hydroxide ions and is said to be neutral. A solution that contains more hydrogen ions than hydroxide ions has a pH less than 7.0 and is acidic. A solution with fewer hydrogen ions than hydroxide ions has a pH greater than 7.0 and is basic (alkaline).

6. The pH of human blood is about 7. 4, and ranges from 7. 35 to 7
The pH of human blood is about 7.4, and ranges from 7.35 to 7.45 (see Figure 2.11).
If the pH of human blood drops below 7.35, the person has acidosis; if it rises above 7.45, the condition is alkalosis. Without medical intervention, a person usually cannot survive if blood pH drops to 6.9 or rises to 7.8 for more than a few hours.
The body maintains homeostasis through a number of self-regulating control systems, or homeostatic mechanisms. The general homeostatic mechanism described in chapter 1 (p. 6 of the course text) may regulate pH.
Figure 2.11

7. Chemical Constituents of Cells:
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Chemical Constituents of Cells:
A. Organic compounds contain both hydrogen and carbon.
B. All other compounds are considered inorganic.
1. Water
a. Water is the most abundant compound in living things and makes up two-thirds of the weight of adults.
b. Water is an important solvent so most metabolic reactions occur in water.
Chemical, including those that enter into metabolic reactions or are produced by them, can be divided into two large groups. Chemicals that include both carbon and hydrogen atoms are called organic. The rest are inorganic.
Inorganic substance usually dissociate in water to release ions; thus, they are electrolytes. Many organic compounds also dissolve in water, but they are more likely to dissolve in organic liquids, such as ether or alcohol.
Organic substances that dissolve in water usually do not release ions and are therefore called nonelectrolytes.

8. Chemical Constituents of Cells: (Inorganic substances continued)
c. Water is important in transporting materials in the body since it is a major component of blood.
d. Water carries waste materials and can absorb and transport heat.
Inorganic substances:
Water is the most abundant substance in the human body. It is a major component of blood and other body fluids. It is an important solvent. It also has an important role in the transportation of chemicals in the body. For example, the aqueous (watery) portion of blood carries many vital substances, such as oxygen, sugars, salts, and vitamins, from the organs of digestion and respiration to the body cells. Additionally, water can absorb and transport heat. Blood carries heat released from muscle cells during exercise from deeper parts of the body to the surface, where it may be lost to the outside.

9. Inorganic substances (continued)
2. Oxygen
a. Oxygen is needed to release energy from nutrients and is used to drive the cell's metabolism.
3. Carbon Dioxide
a. Carbon dioxide is released as a waste product during energy-releasing metabolic reactions.
Inorganic substances:
Molecules of oxygen (O2) enter the body through the respiratory organs and are transported throughout the body by the blood. The red blood cells bind and carry most of the oxygen. Oxygen is used by cellular organelles in the process of releasing energy from glucose and certain other molecules. The resultant energy is used to drive the cell's metabolic activity.
Carbon dioxide (CO2) is a simple, carbon-containing compound of the inorganic group. It is produced as a waste product when certain metabolic processes release energy, and it is exhaled from the lungs.

10. Inorganic substances (continued)
4. Inorganic Salts
a. Inorganic salts provide necessary ions including sodium, chloride, potassium, calcium, magnesium, phosphate, carbonate, bicarbonate, and sulfate.
b. These electrolytes play important roles in many of the body's metabolic processes.
A salt is a compound composed of oppositely charged ions. Sodium (Na+), chlorine (Cl-), potassium (K+), calcium (Ca+), magnesium (Mg++), phosphate (PO4 -3), carbonate (CO3 -2), bicarbonate (HCO3 -), and sulfate (SO4 -2) are the ions that play important roles in metabolic processes—including transport of substances into and out of cells, muscle contraction, and nerve impulse conduction.
Table 2.4, slide 34 summarizes the functions of some of the inorganic substances in cells.

11. Inorganic Substances Common in Cells
Inorganic substances common in cells: inorganic molecules and inorganic ions.

12. c. Humans synthesize the polysaccharide glycogen.
C. Organic Substances:
1. Carbohydrates
a. Carbohydrates provide energy for cellular activities and are composed of carbon, hydrogen, and oxygen.
b. Carbohydrates are made from monosaccharides (simple sugars); disaccharides are two monosaccharides joined together; complex carbohydrates (polysaccharides), such as starch, are built of many sugars.
c. Humans synthesize the polysaccharide glycogen.
Important groups of organic chemicals in cells include carbohydrates, lipids, proteins, and nucleic acids.
Carbohydrates supply much of the energy for the cells. They supply building materials for certain cell structures and are often stored as reserve energy. These molecules contain atoms of carbon, hydrogen, and oxygen. Carbohydrates usually have twice as many hydrogen as oxygen atoms. The carbon atoms are joined in chains that vary in length with the kind of carbohydrate.
Simple carbohydrates are six-carbon sugars known as simple sugars (monosaccharides). The simple sugars include glucose, fructose, and galactose, as well as the 5—carbon sugar ribose and deoxyribose.
In complex carbohydrates, a number of simple sugar molecules link to form molecules of varying sizes. Disaccharides are double sugars, complex carbohydrates, such as sucrose (table sugar) and lactose (milk sugar). Other complex carbohydrates are made up of many simple sugar units joined to form polysaccharides, such as plant starch. Animals, including humans, synthesize a polysaccharide similar to starch called glycogen.

13. Figure 2.12
Structural formulas depict a molecule of glucose
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Figure 2.12, p. 41 in course text – a, b, c are structural formulas depicting a molecule of glucose.
Figure 2.13, p. 42 in course text – carbohydrate molecules vary in size, monosaccharide, disaccharide, and polysaccharide
Figure 2.13
Carbohydrate molecules vary in size: a) monosaccharide. b) disaccharide.
c) polysaccharide

14. Organic Substances (continued)
2. Lipids:
a. Lipids are organic substances that are insoluble in water and include fats, phospholipids, and steroids.
b. Fats supply energy for cellular function, and are built from glycerol and three fatty acids. Fats have a smaller proportion of oxygen atoms than carbohydrates.
i. Fatty acids with hydrogen at every position along the carbon chain are saturated; those with one or more double bonds are called unsaturated
fats.
Lipids are organic substances that are insoluble in water but soluble in certain organic solvents. They supply more energy, gram for gram, than carbohydrates. They contain carbon, hydrogen, and oxygen. Lipids contain a much smaller proportion of oxygen than carbohydrates. Lipids include a variety of compounds—fats, phospholipids, and steroids—that have vital functions in cells. The most common lipids are fats.
Fats are used primarily to store energy for cellular activities. Fat molecules can supply more energy, gram for gram, than carbohydrate molecules. Like carbohydrates, fat molecules are composed of carbon, hydrogen, and oxygen atoms.
The building blocks of fat molecules are fatty acids and glycerol. Each glycerol molecule bonds with three fatty acid molecules to produce a single fat or triglyceride, molecule.
An unsaturated fat contains one or more double bonds between its carbon atoms. A saturated fat contains no double bonds between its carbon atoms.

15. A triglyceride molecule
The building blocks of fat molecules are fatty acids and glycerol. Each glycerol molecule bonds with three fatty acid molecules to produce a single fat, or triglyceride molecule.
Figure 2.14
A triglyceride molecule (fat) consists of a glycerol portion and three fatty acid portions. This is an example of an unsaturated fat. The double bond between carbon atoms in the unsaturated fatty acid is shown in red.

16. Organic Substances (continued)
c. Phospholipids contain glycerol, two fatty acids, and a phosphate group, and are important in cell structures.
d. Steroids are complex ring structures, and include cholesterol, which is used to synthesize the sex hormones.
A phospholipid molecule is similar to a fat molecule in that is consists of a glycerol portion and fatty acid chains. Phospholipids are used as structural components in cell membranes; abundant in liver and parts of the nervous system.
Steroid molecules are complex structures that include four connected rings of carbon atoms. Among the more important steroids are cholesterol, which is in all body cells and is used to synthesize other steroids; sex hormones, such as estrogen, progesterone, and testosterone, and several hormones from the adrenal glands.

17. Important Groups of Lipids
Table 2.5, Important Groups of Lipids: triglycerides, phospholipids, steroids.

18. Organic Substances (continued)
3. Proteins:
a. Proteins have a great variety of functions in the body--as structural materials, as energy sources, as certain hormones, as receptors on cell membranes, as antibodies, and as enzymes to catalyze metabolic reactions.
Proteins can be used as structural materials, energy sources, and hormones. Some others combine with carbohydrates and function as receptors on cell surfaces that are specialized to bond to particular kinds of molecules. Others act as antibodies against foreign substances that enter the body. Still others act as enzymes in metabolic processes.
Many proteins are globular and function as enzymes, ion channels, carrier proteins, or receptors. Myoglobin and hemoglobin, which transport oxygen in muscle and blood, respectively, are globular.

19. Organic Substances (continued)
b. Proteins contain C, O, H, and nitrogen atoms; some also contain sulfur.
c. Building blocks of proteins are the amino acids, each of which has a carboxyl group, an amino group and a side chain called the R group.
Proteins contain atoms of carbon, hydrogen, and oxygen. In addition, they always contain nitrogen atoms, and sometimes contain sulfur atoms as well. The building blocks of proteins are amino acids.

20. Organic Substances (continued)
d. Proteins have complex shapes held together by hydrogen bonds.
e. Protein shapes, which determine how proteins function, can be altered (denatured) by pH, temperature, radiation, or chemicals.
Twenty different amino acids make up the proteins of most living organisms. The amino acids join in polypeptide chains that vary in length from less than 100 to more than 5000 amino acids. A protein molecule consists of one or more polypeptide chains.
Hydrogen bonding and even covalent bonding between atoms in different parts of the polypeptide give the final protein a distinctive three-dimensional shape, or conformation. The conformation of a protein determines its function. Some proteins are long and fibrous, such as the keratin proteins that form hair, or fibrin, the protein whose threads form a blood clot.
When hydrogen bonds in a protein break as a result of exposure to excessive heat, radiation, electricity, pH changes, or various chemicals a protein’s unique shape may be changed dramatically, or denatured. Such proteins lose their special properties. For example, heat denatures the protein in egg white (albumin), changing it for a liquid to a solid. This is an irreversible change—a hard-boiled egg cannot return to its uncooked, runny state. Similarly, cellular proteins that are denatured may be permanently altered and lose their functions.
Proteins have several levels of structure: Primary, secondary, and tertiary levels as shown in Figure 2.18, slide 44).

21. A protein molecule consists of one or more polypeptide chains.
The levels of protein structure sculpt the overall, three-dimensional conformation, which is vital to the protein’s function.
Figure 2.18

22. Organic Substances (continued).
4. Nucleic Acids:
a. Nucleic acids form genes and take part in protein synthesis.
b. They contain carbon, hydrogen, oxygen, nitrogen, and phosphorus, which are bound into building blocks called nucleotides.
These molecules are generally very large and complex. They include atoms of carbon, hydrogen, oxygen, nitrogen, and phosphorus, which form building blocks call nucleotides.

23. Organic Substances (continued)
c. Nucleic acids are of two major types: DNA (with deoxyribose) and RNA (with ribose).
d. RNA (ribonucleic acid) functions in protein synthesis; DNA (deoxyribonucleic acid) stores the molecular code in genes.
Each nucleotide consist of a 5-carbon sugar (ribose or deoxyribose), a phosphate group, and one of several nitrogenous (nitrogen-containing) bases (see Figure 2.20, slide 47).
Nucleic acids are of two types:
One type—RNA (ribonucleic acid)—is composed of molecules whose nucleotides have ribose. RNA usually is a single polynucleotide chain, but it can fold into various shapes that enable it to control when certain genes are accessed (see Figure 2.21 a, slide 48).
The second type—DNA (deoxyribonucleic acid)—has deoxyribose and forms a double polynucleotide chain. The two chains are held together by hydrogen bonds (see Figure 2.21 b, slide 48).
DNA molecules store information in a type of molecular code created by a the sequences of the four types of nitrogenous bases. Cells use this information to synthesize protein molecules. RNA molecules carry out protein synthesis.
Certain nucleotides, such as adenosine triphosphate (ATP), have another role providing energy to certain chemical reactions (ATP will be discussed further in chapter 4).

24. A nucleotide
A nucleotide consists of a 5-carbon sugar (S = sugar), a phosphate group (P = phosphate), and a nitrogenous base
(B = base).
Figure 2.20

25. A schematic representation of nucleic acid structure
A schematic representation of nucleic acid structure. A nucleic acid molecule consists of (a) one (RNA) or two (DNA) polynucleotide chains. DNA chains are held together by hydrogen bonds (dotted lines), and they entwine, forming a double helix.
Figure 2.21

26. Organic Compounds in Cells
Table 2.6 Organic compounds in cells.

27. What’s Next?
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