Ch 2

This chapter builds the chemistry foundation you'll use throughout anatomy and physiology. Many later topics (muscles, nerves, pH, ATP, action potentials) depend on these concepts, so it's worth learning them well.

1. Matter ⭐⭐⭐⭐⭐

Key Terms

• Matter = anything that has mass and occupies space

• Everything in the human body is matter.

States of Matter

Types of Changes

Physical Change

• Changes appearance

• No new substance

• Example: Ice melting, chopping wood

Chemical Change

• Produces a new substance

• Example: Burning wood, digestion

Memory Trick

Physical = Looks different

Chemical = Becomes different

2. Elements & Atoms ⭐⭐⭐⭐⭐

Element

A pure substance made of one type of atom.

Example:

• Oxygen

• Carbon

• Sodium

Atom

The smallest unit of an element.

Know the 4 major body elements (96% of body weight):

• Oxygen (O)

• Carbon (C)

• Hydrogen (H)

• Nitrogen (N)

Know these symbols:

• Na = Sodium

• K = Potassium

• Ca = Calcium

• Mg = Magnesium

• Cl = Chloride

• Fe = Iron

Mnemonic

Our Cells Have Nutrients

(O, C, H, N)

3. Atomic Structure ⭐⭐⭐⭐⭐

Know the three particles.

Remember:

• Protons never leave.

• Neutrons rarely matter for bonding.

• Electrons do all the "moving."

Memory Trick

Proton = Positive

Neutron = Neutral

Electron = Electricity

4. Atomic Number vs. Atomic Mass ⭐⭐⭐⭐

Atomic Number

Number of protons

Determines the element.

Atomic Mass

Protons + Neutrons

Formula:

Neutrons = Atomic Mass − Atomic Number

5. Isotopes ⭐⭐⭐

Isotopes:

• Same number of protons

• Different number of neutrons

Some isotopes are radioactive.

Radioisotopes are used in medical imaging and treatments.

6. Electron Shells ⭐⭐⭐⭐

The outer shell determines how atoms react.

Atoms become stable by:

• Gaining electrons

• Losing electrons

• Sharing electrons

Think of the outer shell as wanting to be "full."

7. Chemical Bonds ⭐⭐⭐⭐⭐

Know all three.

Ionic Bond

Electrons are transferred.

Example:

Na → Cl

Na⁺ + Cl⁻

Memory:

Ionic = I Give

Covalent Bond

Electrons are shared.

Example:

H₂O

Memory:

Cooperate = Share

Hydrogen Bond

Weak attraction between polar molecules.

Example:

Water molecules sticking together.

Memory:

Hydrogen = Hold together

Easy Bond Table

If you remember these three verbs, you'll answer many exam questions correctly.

8. Cations & Anions ⭐⭐⭐⭐⭐

This is tested often.

Cation (+)

Lost electrons

Positive charge

Examples:

Na⁺

K⁺

Ca²⁺

Anion (−)

Gained electrons

Negative charge

Examples:

Cl⁻

HCO₃⁻

Memory Trick:

CATion = PAWsitive

9. Electrolytes ⭐⭐⭐⭐⭐

Electrolytes become ions in water and conduct electricity.

Functions:

• Nerve impulses

• Muscle contraction

• Heart rhythm

• Fluid balance

Know these normal ranges:

10. Functions of Each Electrolyte ⭐⭐⭐⭐⭐

High-Yield Memory

Na = Water

K = Heart

Ca = Bones

Mg = Muscles

P = Power (ATP)

HCO₃ = Buffer

11. Molecules vs. Compounds ⭐⭐⭐

Molecule

Two or more atoms bonded.

Example:

O₂

Compound

Two or more different elements.

Example:

H₂O

Remember:

O₂ = Molecule only

H₂O = Molecule + Compound

12. Water ⭐⭐⭐⭐

Know its five jobs.

Water:

• Universal solvent

• Transports nutrients

• Participates in reactions

• Lubricates tissues

• Regulates body temperature

13. Oxygen & Carbon Dioxide ⭐⭐⭐

Oxygen:

• Used to make ATP

Carbon dioxide:

• Waste product

• Exhaled through lungs

• Affects blood pH

14. Enzymes ⭐⭐⭐⭐

Enzymes:

• Speed up reactions

• Are not used up

• Work best at normal pH and temperature

Remember:

Enzymes = Biological catalysts

15. Acids, Bases & pH ⭐⭐⭐⭐⭐

Acid

• Releases H⁺

• Lowers pH

Base

• Accepts H⁺

• Raises pH

pH Scale

Blood pH:

Normal:

7.35–7.45

Below 7.35:

Acidosis

Above 7.45:

Alkalosis

Memory Trick

More H⁺ = More Acid

16. Blood pH Regulation ⭐⭐⭐⭐

Three systems work together:

1. Buffers (immediate)

2. Lungs (minutes)

3. Kidneys (hours to days)

Think:

Buffer → Lungs → Kidneys

from fastest to slowest.

17. Forms of Energy ⭐⭐⭐

Know all six:

• Mechanical

• Chemical

• Electrical

• Radiant

• Thermal

• Nuclear

Most important:

Chemical energy (food) is converted into mechanical work and heat.

18. ATP ⭐⭐⭐⭐⭐

One of the biggest topics.

ATP is the cell's energy currency.

ATP → ADP + Phosphate + Energy

Breaking the last phosphate bond releases usable energy.

Food rebuilds ATP.

Memory Trick

ATP = Charged Battery

ADP = Drained Battery

19. Solutions, Suspensions & Precipitates ⭐⭐⭐

Know the differences.

Clinical pearl:

Never administer IV medication containing a visible precipitate.

⭐ Most Important Topics (Study These First)

If you're short on time, focus on these:

1. ⭐⭐⭐⭐⭐ Atomic Structure (protons, neutrons, electrons)

2. ⭐⭐⭐⭐⭐ Ionic, Covalent & Hydrogen Bonds

3. ⭐⭐⭐⭐⭐ Cations vs. Anions

4. ⭐⭐⭐⭐⭐ Electrolytes and their functions

5. ⭐⭐⭐⭐⭐ ATP

6. ⭐⭐⭐⭐⭐ Acids, Bases & Blood pH

7. ⭐⭐⭐⭐ Matter & Chemical vs. Physical Changes

8. ⭐⭐⭐⭐ Elements & Atomic Number/Mass

9. ⭐⭐⭐⭐ Enzymes

10. ⭐⭐⭐⭐ Water's functions

11. ⭐⭐⭐ Blood pH regulation (buffers, lungs, kidneys)

12. ⭐⭐⭐ Molecules vs. Compounds

13. ⭐⭐⭐ Solutions, Suspensions & Precipitates

🔥 Since you've already been studying the nervous and muscular systems, pay extra attention to these Chapter 2 concepts because they connect directly to later chapters:

• Electrolytes (Na⁺, K⁺, Ca²⁺) → nerve impulses and muscle contraction.

• ATP → powers muscle contraction and active transport.

• Chemical bonds → explain how molecules like water and proteins form.

• Acids, bases, and blood pH → affect enzyme activity and normal body function.

• Electrons and ions → are the basis of action potentials, depolarization, and repolarization you'll continue to study.