Foundations of Anatomy & Physiology: Scientific Method, Cell Structure, and Biological Chemistry

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The scientific method is a systematic approach used in scientific study to investigate observations, solve problems, and test hypotheses.

Steps of the Scientific Method: Observation, Question, Hypothesis, Experiment, Data Collection, Analysis, Conclusion.
Variables: Independent variable is manipulated; dependent variable is measured.
Control Group: A group not exposed to the experimental variable, used for comparison.
Placebo: An inactive substance or treatment used as a control in experiments.
Example: Testing a new drug, with one group receiving the drug (experimental) and another receiving a placebo (control).

Understanding and interpreting data is essential in scientific research.

Reading Graphs: Identify variables on the x-axis (independent) and y-axis (dependent).
Correlation: Positive correlation means both variables increase together; negative correlation means one increases as the other decreases.
Example: Height and weight often show positive correlation.

Living organisms share certain defining features that distinguish them from nonliving things.

Main Features: Organization, metabolism, responsiveness, growth, development, reproduction, homeostasis, adaptation.
Comparison: Living systems exhibit metabolism and reproduction; nonliving systems do not.

Homeostasis is the maintenance of a stable internal environment in the body.

Definition: The body's ability to maintain internal conditions within a narrow range.
Feedback Loops: Negative feedback reduces the effect of a stimulus (e.g., body temperature regulation); positive feedback amplifies it (e.g., blood clotting).
Examples: Blood glucose regulation (negative feedback), childbirth contractions (positive feedback).

Atoms and molecules form the basis of all living organisms.

Common Elements: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), Sulfur (S).
Electron Arrangement: Electrons are arranged in shells around the nucleus.

Biological macromolecules are large molecules essential for life.

Four Classes: Carbohydrates, lipids, proteins, nucleic acids.
Monomers: Building blocks (e.g., monosaccharides for carbohydrates, amino acids for proteins).
Dehydration Synthesis: Joins monomers by removing water.
Hydrolysis: Breaks polymers into monomers by adding water.

Water's unique properties are vital for life.

Cohesion: Water molecules stick together.
Polarity: Water has a partial positive and negative charge, allowing hydrogen bonding.
Solute vs. Solvent: Solute is dissolved; solvent does the dissolving (water is the universal solvent).
Acids, Bases, Neutrals: Acids release H+, bases release OH-, neutral solutions have equal H+ and OH-.
Example: Blood pH is slightly basic (about 7.4).

Cells are the basic units of life, containing specialized structures called organelles.

Major Organelles: Nucleus, mitochondria, endoplasmic reticulum (ER), Golgi apparatus, lysosomes, peroxisomes.
Ribosomes: Free ribosomes synthesize proteins for the cytosol; ribosomes on the ER synthesize proteins for export or membranes.
Detoxification: Peroxisomes and smooth ER are involved in detoxifying substances and breaking down waste.

Cell membranes are primarily composed of a phospholipid bilayer.

Phospholipids: Have hydrophilic heads and hydrophobic tails, forming a bilayer in water.

Cells regulate the movement of substances across their membranes.

Passive Transport: Movement down a concentration gradient (e.g., diffusion, osmosis).
Facilitated Diffusion: Passive transport via membrane proteins.
Active Transport: Requires energy (ATP) to move substances against a gradient (e.g., sodium-potassium pump).
Sodium-Potassium Pump: Moves 3 Na+ out and 2 K+ into the cell, using ATP.
Endocytosis: Cell engulfs material into vesicles.
Exocytosis: Vesicles fuse with the membrane to release contents outside the cell.
Osmosis: Diffusion of water across a semipermeable membrane.
Cell Solutions: Hypotonic (cell swells), isotonic (no change), hypertonic (cell shrinks).

Microscopes are essential tools for studying cells and tissues.

Cells require energy to perform work, which is provided by ATP.