Anatomy & Physiology: Foundational Concepts and Key Principles

Anatomy & Physiology: Foundational Concepts and Key Principles

Negative Feedback & Positive Feedback

Feedback mechanisms are essential for maintaining homeostasis in the body. They regulate physiological processes by responding to changes in the internal environment.

• Negative Feedback: A process that reverses a deviation from the set point, restoring balance. Most homeostatic mechanisms use negative feedback (e.g., body temperature regulation).

• Positive Feedback: A process that amplifies a change, moving the system further from the set point (e.g., blood clotting, childbirth contractions).

• Example: When blood glucose rises, insulin is released to lower it (negative feedback).

Levels of Organization

The human body is organized into hierarchical levels, each building upon the previous one.

• Chemical Level: Atoms and molecules

• Cellular Level: Cells and their organelles

• Tissue Level: Groups of similar cells

• Organ Level: Two or more tissue types

• Organ System Level: Organs working together

• Organismal Level: The complete living being

Anatomical Position

The standard reference position for the body in the study of anatomy.

• Body stands upright, facing forward

• Arms at the sides, palms facing forward

• Feet slightly apart

Serous Membrane – Pleura, Pericardium

Serous membranes line body cavities and cover organs, producing serous fluid to reduce friction.

• Pleura: Surrounds the lungs

• Pericardium: Surrounds the heart

Abdominal Pelvic Regions

The abdomen is divided for anatomical study and clinical reference.

• Commonly divided into nine regions or four quadrants

• Examples: Right upper quadrant (RUQ), left lower quadrant (LLQ)

Homeostasis

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

• Involves dynamic equilibrium

• Regulated by feedback mechanisms

Characteristics of Life

All living organisms share certain characteristics.

• Organization

• Metabolism

• Responsiveness

• Growth

• Development

• Reproduction

Sagittal, Frontal, Transverse Sections

Body planes are used to describe anatomical sections.

• Sagittal: Divides body into left and right

• Frontal (Coronal): Divides body into anterior and posterior

• Transverse (Horizontal): Divides body into superior and inferior

Body Cavities

Body cavities house and protect internal organs.

• Dorsal cavity: Cranial and vertebral cavities

• Ventral cavity: Thoracic and abdominopelvic cavities

Anatomy vs. Physiology

Anatomy is the study of body structure; physiology is the study of body function.

• Anatomy: What structures are present?

• Physiology: How do those structures work?

pH and H+

pH measures the concentration of hydrogen ions in a solution.

• pH scale: Ranges from 0 (acidic) to 14 (basic), 7 is neutral

• Formula: $pH = -\log[H^+]$

Carbohydrates – Glucose, Glycogen

Carbohydrates are organic molecules that provide energy.

• Glucose: Main energy source for cells

• Glycogen: Storage form of glucose in animals

Electron Numbers in the Energy Levels

Electrons are arranged in energy levels (shells) around the nucleus.

• First shell: up to 2 electrons

• Second shell: up to 8 electrons

• Third shell: up to 18 electrons

Organic vs. Inorganic Molecule

Organic molecules contain carbon and hydrogen; inorganic molecules do not.

• Organic: Glucose, proteins, lipids

• Inorganic: Water, salts, acids, bases

Dehydration Synthesis (Anabolic) vs. Hydrolysis (Catabolic) Chemical Reactions

These reactions are essential for building and breaking down biomolecules.

• Dehydration Synthesis: Joins molecules by removing water (anabolic)

• Hydrolysis: Breaks molecules by adding water (catabolic)

H+, OH-, H2O

Key ions and molecules in biological systems.

• H+: Hydrogen ion (proton)

• OH-: Hydroxide ion

• H2O: Water molecule

Valence Electrons

Valence electrons are electrons in the outermost shell, important for chemical bonding.

• Determine reactivity of an atom

• Example: Oxygen has 6 valence electrons

Interpreting Chemical Formulas

Chemical formulas show the types and numbers of atoms in a molecule.

• Example: H2O = 2 hydrogen atoms + 1 oxygen atom

DNA, RNA

DNA and RNA are nucleic acids that store and transmit genetic information.

• DNA: Double-stranded, stores genetic code

• RNA: Single-stranded, involved in protein synthesis

Osmosis: Isotonic, Hypotonic, Hypertonic

Osmosis is the movement of water across a semipermeable membrane.

• Isotonic: Equal solute concentration; no net water movement

• Hypotonic: Lower solute concentration outside; water enters cell

• Hypertonic: Higher solute concentration outside; water leaves cell

Plasma Membrane Components

The plasma membrane controls entry and exit of substances in cells.

• Lipid bilayer: Phospholipids with hydrophilic heads and hydrophobic tails

• Proteins: Channels, carriers, receptors

• Carbohydrates: Cell recognition

Biomolecules: Carbohydrates, Proteins, Lipids, Nucleic Acids

Major classes of biological macromolecules and their building blocks.

Type	Monomer	Function
Carbohydrates	Monosaccharides	Energy, structure
Proteins	Amino acids	Enzymes, structure, transport
Lipids	Glycerol + fatty acids	Energy storage, membranes
Nucleic Acids	Nucleotides	Genetic information

ATP

Adenosine triphosphate (ATP) is the primary energy carrier in cells.

• Energy is released when ATP is hydrolyzed to ADP + Pi

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

Cell Organelles

Organelles are specialized structures within cells.

• Nucleus: Contains DNA

• Mitochondria: Produce ATP

• Golgi apparatus: Modifies and packages proteins

• Ribosomes: Protein synthesis

• Endoplasmic reticulum: Protein and lipid synthesis

Cell Division: Mitosis

Mitosis is the process of cell division that produces two identical daughter cells.

• Phases: Prophase, metaphase, anaphase, telophase

• Interphase: Cell growth and DNA replication

Cellular Processes

Cells perform various processes to maintain life.

• Phagocytosis: Cell engulfs particles

• Receptor-mediated endocytosis: Specific uptake of molecules

• Exocytosis: Release of substances from cell

Atomic Structure: Atomic Number, Atomic Mass

Atoms are composed of protons, neutrons, and electrons.

• Atomic number: Number of protons

• Atomic mass: Protons + neutrons

Label a DNA Molecule

DNA is a double helix composed of nucleotides.

• Sugar-phosphate backbone

• Nitrogenous bases: Adenine, thymine, cytosine, guanine

Body Cavities

Major body cavities and their contents.

Cavity	Contents
Cranial	Brain
Vertebral	Spinal cord
Thoracic	Heart, lungs
Abdominal	Digestive organs
Pelvic	Reproductive organs, bladder