Foundations of Anatomy & Physiology: Structure, Function, and Basic Chemistry

Why Anatomical and Physiological Knowledge Matters

Understanding anatomical terminology and physiological principles is essential for effective communication and practice in the health sciences. Mastery of these concepts allows students and professionals to accurately describe the human body and its functions.

Anatomy and Physiology: Definitions and Scope

Anatomy

Anatomy is the study of the structure of body parts and their relationships to one another.

• Gross (macroscopic) anatomy: Study of large, visible structures.

• Regional anatomy: Examines all structures in a particular region of the body.

• Systemic anatomy: Focuses on organ systems (e.g., cardiovascular system).

• Surface anatomy: Studies internal structures as they relate to the overlying skin.

• Microscopic anatomy: Examines structures too small to be seen with the naked eye.

  • Cytology: Study of cells.

  • Histology: Study of tissues.

• Developmental anatomy: Studies anatomical and physiological development throughout life.

  • Embryology: Study of development before birth.

Physiology

Physiology is the study of the function of body parts and how they work to carry out life-sustaining activities.

• Often focuses on organ systems (e.g., renal physiology, neurophysiology).

• Physiological abilities depend on chemical reactions in individual cells.

Complementarity of Structure and Function

Function always reflects structure. What a structure can do depends on its specific form. This is known as the principle of complementarity of structure and function.

Levels of Structural Organization in the Human Body

The human body is organized into several levels, each building on the previous one:

• Chemical level: Atoms combine to form molecules.

• Cellular level: Cells are made up of molecules.

• Tissue level: Groups of similar cells form tissues. There are four basic tissue types:

  • Epithelial

  • Connective

  • Muscle

  • Nervous

• Organ level: Organs are made up of two or more types of tissues.

• Organ system level: Organ systems consist of different organs that work closely together. There are 11 organ systems in the human body.

• Organismal level: The human organism is made up of many organ systems working together.

Requirements for Life: Necessary Life Functions

To maintain life, humans must perform several essential functions:

1. Maintaining boundaries: Separation between internal and external environments (e.g., skin, plasma membranes).

2. Movement: Includes movement of body parts (skeletal muscle), substances (cardiac and smooth muscle), and cellular movement.

3. Responsiveness: Ability to sense and respond to stimuli (e.g., withdrawal reflex, control of breathing rate).

4. Digestion: Breakdown of ingested foodstuffs, followed by absorption of simple molecules into the blood.

5. Metabolism: All chemical reactions that occur in body cells, including:

   • Catabolism: Breakdown of molecules.

   • Anabolism: Synthesis of molecules.

6. Excretion: Removal of wastes from metabolism and digestion (e.g., urea, carbon dioxide, feces).

7. Reproduction: Cellular division for growth or repair; production of offspring.

8. Growth: Increase in size of a body part or of the organism.

Basic Chemistry for Anatomy & Physiology

Structure of Atoms

Atoms are the smallest units of matter that retain the properties of an element. They are composed of subatomic particles:

• Protons: Carry a positive charge (+), located in the nucleus, mass = 1 atomic mass unit (amu).

• Neutrons: No charge (neutral), located in the nucleus, mass = 1 amu.

• Electrons: Carry a negative charge (–), orbit the nucleus, mass is negligible.

Identifying Elements

• Each element contains different numbers of subatomic particles, which determines its chemical and physical properties.

• Atomic number: Number of protons in the nucleus. Written as a subscript to the left of the atomic symbol.

• Mass number: Total number of protons and neutrons in the nucleus. Written as a superscript to the left of the atomic symbol.

• Isotopes: Structural variations of the same element; differ in the number of neutrons.

• Atomic weight: Average of mass numbers of all isotopes of an atom.

Table: Comparison of Subatomic Particles

Particle	Charge	Location	Mass (amu)
Proton	+1	Nucleus	1
Neutron	0	Nucleus	1
Electron	–1	Electron cloud/orbitals	~0

Radioisotopes

• Isotopes that decompose to more stable forms by emitting radiation.

• As radioisotopes decay, subatomic particles are released, sometimes resulting in a different element.

• Radioisotopes are used in medical imaging and cancer treatment.

Chemical Bonds and Compounds

Types of Matter

• Elements: Pure substances composed of only one type of atom.

• Compounds: Two or more different kinds of atoms chemically bonded together.

• Mixtures: Two or more components physically intermixed; can be homogeneous (solutions) or heterogeneous.

Chemical Bonds

Chemical bonds are energy relationships between electrons of reacting atoms. They determine whether a chemical reaction will take place and what type of chemical bond is formed.

• Electrons are the subatomic particles involved in all chemical reactions.

• Electrons occupy regions called electron shells around the nucleus.

• Each shell has a specific energy level and a maximum number of electrons:

  • Shell 1: 2 electrons

  • Shell 2: 8 electrons

  • Shell 3: 18 electrons

• The outermost shell is called the valence shell. Electrons in this shell are involved in chemical reactions.

Octet Rule

Atoms tend to interact in such a way that they have eight electrons in their valence shell (except for smaller atoms like hydrogen and helium, which are stable with two electrons).

• Atoms will gain, lose, or share electrons to achieve stability.

Major Types of Chemical Bonds

1. Ionic bonds: Transfer of electrons from one atom to another.

2. Covalent bonds: Sharing of electrons between atoms.

3. Hydrogen bonds: Weak attractions between a hydrogen atom and an electronegative atom.

Summary Table: Levels of Organization and Life Functions

Level	Description	Example
Chemical	Atoms and molecules	Water (H2O), glucose
Cellular	Cells and their organelles	Muscle cell
Tissue	Groups of similar cells	Muscle tissue
Organ	Contains two or more tissue types	Heart
Organ System	Organs that work closely together	Cardiovascular system
Organismal	All organ systems combined	Human being

Key Equations and Concepts

• Atomic number: $\text{Atomic number} = \text{Number of protons}$

• Mass number: $\text{Mass number} = \text{Number of protons} + \text{Number of neutrons}$

• Atomic weight: $\text{Atomic weight} = \text{Average mass of all isotopes of an element}$

Additional info:

• Some context and terminology were expanded for clarity and completeness, such as the full list of life functions and the explanation of chemical bonds.

• Tables were reconstructed and summarized based on standard academic knowledge.