Anatomy & Physiology: Cell Structure, Body Organization, and Organ Systems Study Guide

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Cells contain specialized structures called organelles that perform distinct functions necessary for cellular life and homeostasis.

Rough Endoplasmic Reticulum (Rough ER): Synthesizes proteins for secretion; characterized by ribosomes on its surface.
Smooth Endoplasmic Reticulum (Smooth ER): Involved in lipid and cholesterol synthesis, and detoxification processes.
Golgi Apparatus: Packages proteins into vesicles for transport within or outside the cell.
Lysosomes: Digest worn-out organelles and foreign material; contain hydrolytic enzymes.
Mitochondria: Double-membraned organelles responsible for ATP production via cellular respiration.
Cytoskeleton: Provides structural support, enables movement, and facilitates intracellular transport.
Centrosome/Centrioles: Organize spindle fibers during mitosis for chromosome separation.

Transport across the cell membrane is essential for maintaining cellular homeostasis and involves both passive and active processes.

Passive Processes: Do not require cellular energy (ATP); include diffusion, osmosis, and filtration.
- Diffusion: Movement of molecules from high to low concentration.
- Osmosis: Diffusion of water across a selectively permeable membrane.
- Filtration: Movement driven by hydrostatic pressure (e.g., filtration in kidneys).
- Example: Red blood cells in hypotonic solution swell as water enters (hemolysis); isotonic solutions have equal solute concentrations inside and outside the cell.
Active Processes: Require energy (ATP); include phagocytosis, pinocytosis, and exocytosis.
- Phagocytosis: "Cell eating"; uptake of large particles.
- Pinocytosis: "Cell drinking"; uptake of liquids into the cell.
- Exocytosis: Release of substances out of the cell via vesicles.

Key Equation:

Body cavities house and protect internal organs, and are lined by membranes.

Abdominopelvic cavity: Large cavity containing many organs, divided into quadrants.
Pericardium: Membrane surrounding the heart.
Pleura: Membrane surrounding the lungs.
Peritoneum: Membrane lining the abdominopelvic cavity.

Planes are imaginary lines used to divide the body for anatomical study.

Transverse (Horizontal): Divides body into superior (upper) and inferior (lower) parts.
Frontal (Coronal): Divides body into anterior (front) and posterior (back) parts.
Sagittal: Divides body into left and right parts.

Directional terms describe the locations of structures relative to other structures or locations in the body.

Epithelial tissues line body surfaces and cavities, providing protection and facilitating absorption and secretion.

Simple squamous endothelium: Thin layer lining blood vessels, allowing for efficient exchange.
Transitional epithelium: Found in bladder and ureters; allows stretching.
Peritoneum: Serous membrane of the abdomen.
Microvilli: Increase surface area for absorption, especially in the intestines.

Excretory organs remove waste products and maintain internal balance.

The endocrine system regulates body functions through hormones.

Thyroid gland: Endocrine gland regulating metabolism.
Hormones: Chemical messengers controlling growth, metabolism, and calcium balance.

The nervous system enables rapid communication and control throughout the body.

Defends the body against pathogens and removes debris.

Responsible for gas exchange and transport of oxygen and carbon dioxide.

The abdominopelvic cavity is divided into regions and quadrants for anatomical reference.