Introduction to Anatomy & Physiology

Anatomy vs. Physiology

Anatomy and physiology are foundational sciences for understanding the human body. Anatomy focuses on the structure of body parts, while physiology studies their functions.

• Anatomy: Study of the structure of body parts.

• Physiology: Study of the function of body parts.

• Example: Anatomy describes the chambers of the heart; physiology explains how those chambers pump blood.

Levels of Organization in the Human Body

Structural Hierarchy

The human body is organized into a hierarchy of increasing complexity, from atoms to the whole organism.

• Levels: Atoms → Cells → Tissues → Organs → Systems → Organism

• Example: Heart muscle cell (Cellular) → Cardiac muscle tissue (Tissue) → Heart (Organ) → Cardiovascular System (System) → Human (Organism)

Homeostasis

Definition and Importance

Homeostasis is the dynamic maintenance of a stable internal environment despite external changes.

• Definition: The body's dashboard, keeping internal conditions stable.

• Example: Your body sweats to cool down when it's hot and shivers to warm up when it's cold, maintaining a ~98.6°F set point.

Feedback Loops

Negative vs. Positive Feedback

Feedback loops regulate physiological processes. Negative feedback reverses a change to return to a set point, while positive feedback amplifies a change to complete a process.

• Negative Feedback: Stops the stimulus. Example: Insulin lowering high blood sugar.

• Positive Feedback: Amplifies the stimulus. Example: Oxytocin intensifying contractions until childbirth.

Gradients in Physiology

Definition and Examples

A gradient is a difference that makes things flow from high to low.

• Example: Concentration Gradient: Perfume spreading across a room. Pressure Gradient: Blood moving from high-pressure heart to low-pressure vessels.

Atomic Structure and Elements

Subatomic Particles

Atoms are composed of protons, neutrons, and electrons, each with distinct properties and locations.

• Protons: Positive, in the nucleus, mass of 1 amu.

• Neutrons: Neutral, in the nucleus, mass of 1 amu.

• Electrons: Negative, in orbitals, negligible mass.

• Example: In a Carbon atom, 6 protons and 6 neutrons are in the center; 6 electrons whirl around it.

Major Elements in the Human Body

Four elements constitute about 96% of the human body mass.

• Elements: Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N)

Atomic Number, Mass Number, and Isotopes

Atoms are identified by their atomic number and mass number. Isotopes are atoms of the same element with different neutron counts.

• Atomic Number: Number of protons in the nucleus.

• Mass Number: Number of protons + neutrons.

• Isotopes: Same element, different neutron counts.

• Example: Carbon-12 (6p, 6n) and Carbon-14 (6p, 8n) are isotopes of Carbon.

Mixtures and Chemical Bonds

Types of Mixtures

Mixtures are combinations of substances that retain their individual properties.

• Solution: Salt water (homogeneous)

• Colloid: Milk (particles do not settle)

• Suspension: Blood in a test tube (cells settle)

Valence Electrons and Stability

The number of electrons in an atom's valence shell determines its chemical stability and bonding ability.

• Full valence shell: Stable (e.g., Neon)

• Incomplete valence shell: Reactive (e.g., Sodium)

Molecule, Compound, and Ion

These terms describe different chemical entities.

• Molecule: Bonded atoms (O2, H2O)

• Compound: Atoms of different elements (H2O)

• Ion: Charged atom/molecule (Na+, Cl-)

Chemical Bonds: Ionic, Nonpolar Covalent, Polar Covalent

Chemical bonds form by electron transfer or sharing.

• Ionic Bond: Steals electrons. Example: NaCl

• Nonpolar Covalent Bond: Shares electrons equally. Example: H2

• Polar Covalent Bond: Shares electrons unequally. Example: H2O

Water and Its Properties

Surface Tension and Hydrogen Bonds

Water molecules stick together due to hydrogen bonds, creating surface tension.

• Hydrogen Bond: Weak attraction between a hydrogen atom and an electronegative atom (O or N).

• Surface Tension: Cohesive hydrogen bonding at the water's surface.

• Example: Water strider insect can walk on water due to surface tension.

Factors Affecting Chemical Reaction Rates

Chemical reaction rates are influenced by concentration, heat, catalysts, and surface area.

• Higher concentration, temperature, presence of catalyst, and greater surface area increase reaction rates.

• Example: A glowing splint bursts into flames in pure oxygen (higher concentration).

Energy in Chemical Reactions

Forms of Energy

Energy exists as potential (stored) or kinetic (motion). Chemical bonds represent potential energy.

• Potential Energy: Stored energy (e.g., in chemical bonds)

• Kinetic Energy: Energy of motion (e.g., heat, light)

Exergonic vs. Endergonic Reactions

Exergonic reactions release energy; endergonic reactions absorb energy.

• Exergonic: Products have less energy than reactants. Example: Burning wood.

• Endergonic: Products have more energy than reactants. Example: Photosynthesis.

Enzymes

Properties and Actions

Enzymes are biological protein catalysts that speed up reactions by lowering activation energy.

• Specificity: Each enzyme acts on a particular substrate.

• Example: Lactase breaks down lactose in milk.

Water: Physiological Importance

Key Properties

Water is essential for life due to its high heat capacity, heat of vaporization, universal solvent properties, cohesion, and chemical reactivity.

• High heat capacity and heat of vaporization help regulate body temperature.

• Universal solvent: Dissolves many substances.

• Example: Sweat cools you because water has a high heat of vaporization.

Solubility in Water

Polar and ionic compounds dissolve in water; nonpolar compounds do not.

• Like dissolves like: Polar/ionic = yes. Nonpolar = no.

Acids, Bases, and pH

Properties of Acids and Bases

Acids are H+ donors; bases are H+ acceptors.

• Acid: Increases H+ concentration. Example: HCl (stomach acid).

• Base: Decreases H+ concentration. Example: NaOH (lye).

pH Scale

The pH scale measures the concentration of hydrogen ions (H+) in a solution.

• Acidic: pH < 7

• Neutral: pH = 7

• Basic: pH > 7

• Example: Lemon juice (pH ~2), pure water (pH 7), bleach (pH ~13)

Buffers

Buffers resist changes in pH by absorbing excess H+ or OH- ions.

• Example: The bicarbonate buffer system in your blood maintains a stable pH around 7.4.

Electrolytes and Salts

Definitions

Salts are ionic compounds; electrolytes are ions that conduct electricity in solution.

• Salt: Ionic compound.

• Electrolyte: Substance that produces ions in water, allowing it to conduct electricity.

Summary Table: Types of Chemical Bonds

Summary Table: Types of Mixtures

Additional info:

• Some prompts and explanations were expanded for clarity and completeness.

• Scientific terms and examples were inferred and clarified based on standard Anatomy & Physiology curriculum.