Study Notes — Organized by Source Flashcards

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Anatomical Terminology

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The system of prefixes, suffixes, and roots used to name body structures and locations precisely. It enables clear communication in the lab and workplace by standardizing how structures and relationships are described. Mastery helps in understanding more complex anatomical and clinical concepts.

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Anatomical Position

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The standard reference posture in which the body is erect, feet slightly apart, palms facing forward, and thumbs pointing laterally. Directional terms are always applied as if the body is in this position. Using this position prevents ambiguity when describing locations.

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Directional Terms

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Words that describe the locations of structures relative to other structures (e.g., anterior, posterior, medial, lateral). They assume the anatomical position and provide consistent spatial reference across contexts. Proper use avoids misunderstandings in anatomy and clinical settings.

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Body Planes

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Imaginary flat surfaces (sagittal, frontal/coronal, transverse) used to divide the body for dissection and imaging. Sagittal divides right and left, frontal divides anterior and posterior, and transverse divides superior and inferior. These planes help describe cross-sections and interpret scans like MRI and CT.

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Homeostasis

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The maintenance of a stable internal environment despite external change. Homeostatic mechanisms use receptors, a control center, and effectors to monitor and adjust variables around a set point. Proper homeostasis is essential for health and normal physiological function.

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Negative Feedback

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A homeostatic mechanism where effectors work to return a variable toward its set point, reducing the deviation. It is the most common feedback type and prevents sudden, large changes in conditions. Examples include regulation of body temperature, blood pressure, and blood glucose.

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Positive Feedback

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A feedback mechanism that intensifies a deviation instead of reversing it, often producing rapid, short-lived effects. Though uncommon, it is important in processes that must proceed to completion like blood clotting and childbirth contractions. Positive feedback typically operates until an event ends the cycle.

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Organ Systems

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Groups of organs that work together to perform major body functions such as circulation, respiration, digestion, and control. Each system has specialized structures and coordinated roles that maintain the organism’s survival. Understanding systems helps integrate anatomy and physiology across levels.

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Medical Imaging

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Techniques used to visualize internal body structures, including radiographs (X-rays), CT scans, MRI, PET, and ultrasound. Each modality has strengths: X-rays for dense structures, CT for detailed cross-sections, MRI for soft tissues, PET for metabolic activity, and ultrasound for real-time imaging. Choice depends on diagnostic need and safety considerations.

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Requirements of Life

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Environmental factors organisms need to survive: water, food, oxygen, heat, and pressure. Water (e.g., $H_2O$) is the most abundant and is essential for metabolic reactions and transport. These requirements support metabolism, growth, and homeostasis.

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Hypothesis vs Theory

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A hypothesis is a suggested explanation or testable prediction for an observed phenomenon. A theory is a well-substantiated, extensively tested unifying explanation supported by reproducible data. Theories are not mere guesses but represent the highest level of scientific understanding.

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Histology

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The microscopic study of tissues, including their structure, function, and location. Histology examines epithelial, connective, muscle, and nervous tissues to understand how cell groups form organs. It provides the basis for correlating structure with physiological function.

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Epithelial Tissue

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Tissue that covers body surfaces and lines cavities, serving functions such as protection, secretion, absorption, diffusion, filtration, and sensory reception. Epithelia are cellular, polarized, supported by connective tissue, avascular, innervated, and have high regenerative capacity. They form continuous sheets held together by specialized junctions.

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Cellularity

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A feature of epithelial tissue characterized by being composed almost entirely of closely packed cells with minimal extracellular material. High cellularity allows efficient barrier and transport functions but requires specialized junctions for cohesion. This contrasts with connective tissues that have abundant extracellular matrix.

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Tight Junctions

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Cell junctions in the apical region of epithelia that form an impermeable seal to prevent molecules from passing between cells. They help maintain distinct apical and basolateral environments by restricting diffusion. Tight junctions are essential for barrier and absorptive functions.

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Desmosomes

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Anchoring junctions that bind adjacent cells together and distribute mechanical stress via an internal network of fibers. They function like a zipper to resist tearing and maintain tissue integrity under tension. Desmosomes are abundant in tissues subject to stretching, such as skin and cardiac muscle.

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Gap Junctions

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Communicating junctions that allow ions and small molecules to pass directly between adjacent cells through channels. They enable rapid electrical and metabolic coupling, important in tissues like cardiac muscle and some epithelia. Gap junctions support coordinated activity across cell networks.

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Basement Membrane

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A thin, non-cellular layer of proteins separating epithelium from underlying connective tissue, composed of the basal lamina plus reticular fibers. It acts as a selective filter and scaffold for tissue repair and cell migration. Basement membrane alterations can lead to clinical problems such as kidney and retinal dysfunction.

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Microvilli

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Finger-like extensions of the apical plasma membrane of epithelial cells that greatly increase surface area for absorption. They are common on absorptive surfaces such as intestinal and kidney tubule epithelia. Microvilli enhance transport capacity without increasing tissue thickness.

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Cilia

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Motile, hair-like projections on the apical surface of certain epithelial cells that move mucus and other substances across the epithelial surface. They are abundant in the respiratory tract and female reproductive tract, where they help clear particles or transport ova. Ciliary dysfunction impairs these clearing and transport processes.

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Simple Squamous

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A single layer of flattened cells with central, flattened nuclei, adapted for rapid diffusion and filtration. It forms structures like alveoli of the lungs and the lining of blood vessels (endothelium). Because it is thin, protection is not its primary role.

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Stratified Squamous

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A thick epithelial membrane composed of several cell layers that primarily provides protection against abrasion and invasion. The skin epidermis is keratinized for waterproofing, while mucosal linings (esophagus, mouth, vagina) are non-keratinized. Basal cells divide to replace eaten surface cells.

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Transitional Epithelium

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An epithelium with multiple cell layers whose surface cells are dome-shaped and can stretch to allow distension. It lines the urinary bladder, ureters, and part of the urethra and accommodates fluctuation in urine volume. Its unique shape provides both protection and elasticity.

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Gland

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A cell or group of cells that synthesizes and secretes an aqueous fluid or lipid/steroid-rich product. Glands are classified by site of product release: endocrine glands are ductless and release hormones into the blood, while exocrine glands use ducts to secrete onto body surfaces or into cavities. Gland structure reflects their secretory role.

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Connective Tissue

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Tissue type that supports, binds, and protects other tissues, characterized by relatively few cells embedded in abundant extracellular matrix. The matrix consists of fibers (collagen, elastic, reticular) and ground substance, which together determine strength and elasticity. Connective tissues range from loose areolar to dense, cartilage, bone, and blood.

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Extracellular Matrix

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The nonliving material between cells composed of ground substance and fibers that provides structural support and biochemical cues. It can be liquid, gel-like, or solid (as in bone) and accounts for a substantial portion of body mass. The extracellular matrix integrates tissues and influences cell behavior and organ function.

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Ground Substance

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The amorphous, gel-like component of the extracellular matrix that fills spaces between cells and fibers, facilitating diffusion of nutrients and waste. It contains water, proteoglycans, glycosaminoglycans, and adhesion proteins; in some contexts blood-related fluid is about 90% $H_2O$. Ground substance helps resist compressive forces and cushions tissues.

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Cartilage Types

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Three cartilage varieties are hyaline (glassy, at articular surfaces and nose), fibrocartilage (tough, in intervertebral discs), and elastic cartilage (flexible, in the ear). Each type differs in fiber content and mechanical properties to suit its functional demands. Cartilage is avascular and heals slowly compared with many tissues.

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Inflammation

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The nonspecific, local tissue response to injury characterized by heat (calor), redness (rubor), swelling (tumor), and pain (dolor). Chemical signals dilate blood vessels and increase capillary permeability, producing edema and bringing immune cells and nutrients to the site. Inflammation limits damage and initiates repair.