Introduction to Anatomy & Physiology

Definitions and Scope

Anatomy and physiology are two closely related branches of biology that study the human body. Anatomy focuses on the structure of body parts and their relationships to one another, while physiology concerns the function of the body, explaining how body parts work and carry out life-sustaining activities.

• Anatomy: The study of the structure of body parts and their relationships.

• Physiology: The study of the function of body parts and how they work together to sustain life.

Levels of Structural Organization

The human body is organized into hierarchical levels, each with increasing complexity:

• Chemical level: Atoms and molecules, the building blocks of matter.

• Cellular level: Cells, the basic units of life.

• Tissue level: Groups of similar cells performing a common function (e.g., blood, muscle, nerves).

• Organ level: Structures composed of two or more tissue types that perform specific functions.

• Organ system level: Groups of organs working together to accomplish a common purpose.

• Organismal level: The complete living organism.

Essential Life Functions

Maintaining Boundaries

Separation between internal and external environments is vital for homeostasis.

• Plasma membranes separate cells.

• Skin separates the organism from the environment.

Movement

• Muscular system allows movement of body parts via skeletal muscles.

• Movement of substances via cardiac muscle (blood) and smooth muscle (digestion, urination).

Responsiveness

• Ability to sense and respond to stimuli.

• Withdrawal reflex prevents injury.

• Control of breathing rate in response to activity.

Digestion

• Breakdown of ingested foodstuffs.

• Absorption of simple molecules into blood.

Metabolism

• All chemical reactions that occur in body cells.

• Sum of catabolism (breakdown of molecules) and anabolism (synthesis of molecules).

Reproduction

• Cellular level: division of cells for growth or repair.

• Organismal level: production of offspring.

Growth

• Increase in size of a body part or of the organism.

Organ Systems Overview

Humans are multicellular; organ systems are designed to service the cells. All cells depend on organ systems to meet their survival needs. There are 11 organ systems that work together to maintain life:

1. Integumentary System: Forms the external body covering, protects deeper tissues, synthesizes vitamin D, and houses cutaneous receptors and sweat/oil glands.

2. Skeletal System: Protects and supports body organs, provides a framework for muscles, and produces blood cells.

3. Muscular System: Allows locomotion, maintains posture, and produces heat.

4. Nervous System: Fast-acting control system; responds to internal/external changes by activating muscles and glands.

5. Endocrine System: Glands secrete hormones that regulate growth, reproduction, and metabolism.

6. Cardiovascular System: Blood vessels transport blood carrying oxygen, carbon dioxide, nutrients, and wastes; heart pumps blood.

7. Lymphatic/Immune System: Returns fluid to blood, disposes of debris, houses lymphocytes, and mounts immune responses.

8. Respiratory System: Keeps blood supplied with oxygen and removes carbon dioxide; gaseous exchanges occur in lungs.

9. Digestive System: Breaks down food and absorbs nutrients; eliminates indigestible foodstuffs.

10. Urinary System: Eliminates nitrogenous wastes; regulates water, electrolytes, and acid-base balance.

11. Reproductive System: Produces offspring; male and female systems have specialized structures and functions.

Survival Needs

Humans require several factors for survival, each in appropriate amounts:

• Nutrients

• Oxygen

• Water

• Normal body temperature

• Appropriate atmospheric pressure

Homeostasis

Definition and Mechanisms

Homeostasis is the maintenance of a stable internal environment despite changes in external conditions. It is a dynamic process involving constant monitoring and adjustment.

• Homeostatic control mechanisms are generally self-regulating and maintain a steady state.

• All mechanisms involve at least three components: receptor, control center, and effector.

Feedback Mechanisms

• Negative feedback: Output shuts off the original effect of the stimulus or reduces its intensity. Most homeostatic mechanisms use negative feedback (e.g., body temperature regulation).

• Positive feedback: Response enhances the original stimulus so that the response is accelerated. Rare in life (e.g., blood clotting, labor contractions).

Basic Chemistry for Anatomy & Physiology

States of Matter

Matter exists in three states:

• Solid: Definite shape and volume.

• Liquid: Definite volume, changeable shape.

• Gas: Changeable shape and volume.

Energy

• Energy does not have mass or occupy space.

• The greater the work done, the more energy is used.

Kinetic vs. Potential Energy

• Kinetic energy: Energy in action.

• Potential energy: Stored (inactive) energy.

• Energy can be transformed from potential to kinetic.

Forms of Energy

• Chemical energy: Stored in bonds of chemical substances.

• Electrical energy: Results from movement of charged particles.

• Mechanical energy: Directly involved in moving matter.

• Radiant energy: Energy that travels in waves (e.g., light).

Energy Conversions

• Energy may be converted from one form to another (e.g., electrical to light energy).

• Energy conversion is inefficient; some energy is lost as heat.

Atoms and Elements

• All matter is composed of elements.

• Four elements make up 96% of the body: carbon (C), hydrogen (H), oxygen (O), nitrogen (N).

• Periodic table lists all known elements.

• Elements are made up of atoms, which are unique building blocks for each element.

Atomic Structure

• Atoms are composed of three subatomic particles:

  • Protons: Positive charge, found in nucleus.

  • Neutrons: No charge, found in nucleus.

  • Electrons: Negative charge, orbit around nucleus.

• Number of protons is balanced by number of electrons, making atoms electrically neutral.

• Protons and neutrons are found in a centrally located nucleus; electrons orbit around the nucleus.

Atomic Number and Mass Number

• Atomic number: Number of protons; written as subscript to left of atomic symbol (e.g., 6C).

• Mass number: Total number of protons and neutrons; written as superscript to left of atomic symbol (e.g., 12C).

Isotopes

• Structural variations of the same element; same atomic number, different mass numbers.

Molecules and Compounds

• Molecule: General term for two or more atoms bonded together.

• Compound: Specific molecule that has two or more different kinds of atoms bonded together.

Mixtures

• Solutions: Homogeneous mixtures; particles evenly distributed.

• Colloids: Heterogeneous mixtures; particles not evenly distributed, appear cloudy.

• Suspensions: Heterogeneous mixtures with large, visible solutes that settle out.

Chemical Bonds

• Ionic bonds: Transfer of electrons from one atom to another, resulting in ions.

• Covalent bonds: Sharing of electrons between atoms.

• Polar covalent bonds: Unequal sharing of electrons, resulting in partial charges (e.g., water).

• Nonpolar covalent bonds: Equal sharing of electrons.

• Hydrogen bonds: Weak attractions between polar molecules.

Chemical Reactions

• Synthesis (combination) reactions: Atoms or molecules combine to form larger molecules.

• Decomposition reactions: Molecules are broken down into smaller molecules or atoms.

• Exchange reactions: Bonds are both made and broken (e.g., AB + CD → AD + CB).

Energy Flow in Chemical Reactions

• Exergonic reactions: Net release of energy; products have less potential energy than reactants.

• Endergonic reactions: Net absorption of energy; products have more potential energy than reactants.

Rate of Chemical Reactions

• Influenced by temperature, concentration of reactants, and particle size.

Water, Salts, Acids, and Bases

Water

• Most abundant inorganic compound in the body.

• High heat capacity, solvent properties, cushioning, and reactivity.

Salts

• Compounds that dissociate into ions in water.

• Electrolytes conduct electrical currents in solution.

• Ionic balance is vital for homeostasis.

Acids and Bases

• Acids: Proton donors; release H+ ions.

• Bases: Proton acceptors; release OH- ions.

• pH scale: Measures concentration of hydrogen ions; ranges from 0 (acidic) to 14 (basic), with 7 being neutral.

Organic Compounds

Carbohydrates

• Include sugars and starches; contain C, H, and O in a 2:1 ratio.

• Monosaccharides: Simple sugars (e.g., glucose).

• Disaccharides: Double sugars (e.g., sucrose, maltose, lactose).

• Polysaccharides: Polymers of monosaccharides (e.g., starch, glycogen).

Lipids

• Contain C, H, O (less O than carbohydrates); sometimes P.

• Triglycerides: Composed of three fatty acids bonded to glycerol; function in energy storage, insulation, and protection.

• Saturated fats: Single bonds; solid at room temperature.

• Unsaturated fats: One or more double bonds; liquid at room temperature.

• Phospholipids: Important in cell membrane structure; have hydrophilic head and hydrophobic tail.

• Steroids: Four interlocking rings; cholesterol is the most important steroid.

Proteins

• Comprise 20-30% of cell mass; contain C, H, O, N, sometimes S and P.

• Polymers of amino acids joined by peptide bonds.

• Four levels of structure: primary, secondary, tertiary, quaternary.

• Fibrous proteins: Strand-like, water-insoluble, stable.

• Globular proteins: Compact, spherical, water-soluble, sensitive to environmental changes.

• Enzymes: Biological catalysts that speed up chemical reactions by lowering activation energy.

Nucleic Acids

• Composed of C, H, O, N, P; largest molecules in the body.

• Polymers of nucleotides (nitrogen base, pentose sugar, phosphate group).

• DNA: Double-stranded helix; genetic blueprint for protein synthesis.

• RNA: Single-stranded; links DNA to protein synthesis.

ATP (Adenosine Triphosphate)

• Chemical energy released from glucose breakdown is captured in ATP.

• ATP directly powers chemical reactions in cells.

Key Equations and Formulas

• General formula for monosaccharides: $C_nH_{2n}O_n$

• pH calculation: $pH = -\log[H^+]$

• ATP hydrolysis: $ATP + H_2O \rightarrow ADP + P_i + \text{energy}$

Summary Table: Major Organ Systems and Functions

Additional info: Some content was inferred and expanded for clarity and completeness, including the list of survival needs and the summary table of organ systems.