Patho 1

Organelle

A functional component inside a cell (e.g., nucleus, mitochondria, lysosomes).

Cell

The basic structural and functional unit of life.

Tissue

A group of similar cells performing the same function.

Organ

A group of tissues working together.

Organ System

Multiple organs functioning cohesively.

Somatic Cells

Non-sex cells such as red blood cells, muscle cells, osteocytes, neurons.

Plasma Membrane

The outer boundary of the cell; a phospholipid bilayer that creates a selective barrier.

Phospholipid Bilayer

The structure of the plasma membrane, consisting of hydrophilic (water-loving) polar heads on outside/inside surfaces and hydrophobic (water-fearing) fatty acid tails facing inward.

Cytosol

The intracellular fluid inside the cell but outside organelles.

Nucleus

The brains/center of the cell; contains genetic material (DNA) directing cell activities.

Nuclear Envelope

A double-layered, porous membrane that regulates entry/exit of signals to and from the nucleus.

Nucleolus

A spherical structure within the nucleus; the primary site for ribosome production and assembly.

Ribosomes

Organelles that carry out protein synthesis, often found on the rough endoplasmic reticulum or free in the cytoplasm.

Lysosomes

Digestive organelles containing enzymes that break down waste materials, damaged components, and are integral to apoptosis.

Peroxisomes

Organelles containing enzymes that decompose hydrogen peroxide (H_2O_2) and other toxins.

Apoptosis

Programmed cell death; a controlled dismantling of a cell with little/no inflammatory response, essential for development, homeostasis, and immune function.

Mitochondria

The 'powerhouses' of the cell; convert food/materials into usable energy (ATP) and contain their own DNA.

ATP (Adenosine Triphosphate)

The energy currency of the cell, providing energy through hydrolysis into ADP and inorganic phosphate.

Endoplasmic Reticulum (ER)

A network of membranous tubules that communicates with the nucleus and other membranes, involved in protein and lipid synthesis.

Rough ER

Endoplasmic reticuluem studded with ribosomes; the site of protein synthesis destined for secretion or membranes.

Smooth ER

Endoplasmic reticuluem that lacks ribosomes; involved in lipid synthesis.

Golgi Apparatus

The 'FedEx/UPS of the cell'; modifies, sorts, and packages proteins and lipids for transport within or outside the cell.

Cytoskeleton

A network of protein filaments (microtubules, intermediate filaments, microfilaments) that provide structural support, maintain cell shape, position organelles, and aid in movement.

Passive Transport

Movement of substances across the plasma membrane that does not require cellular energy (e.g., diffusion, facilitated diffusion).

Diffusion

Passive movement of solutes down their concentration gradient (from an area of high concentration to low concentration).

Facilitated Diffusion

Passive movement of substances across the membrane via channel proteins (tunnels) or carrier proteins (one molecule at a time).

Active Transport

Movement of substances against their concentration gradient (from low to high) that requires energy, usually ATP.

Osmosis

The movement of water across a selectively permeable membrane, aiming to balance solute concentrations across compartments.

Homeostasis

The cell's goal to maintain proper volume and composition, often referring to isotonic balance.

Exocytosis

An active process to eject material from the cell, requiring energy for vesicle formation and transport.

Endocytosis

Cellular uptake of materials; includes phagocytosis (engulfment of solids) and pinocytosis (uptake of liquids).

Phagocytosis

A form of endocytosis involving the engulfment of large solid particles (e.g., debris or pathogens), forming a phagosome/food vacuole.

Pinocytosis

A form of endocytosis involving the uptake of extracellular fluid and dissolved solutes via small vesicles.

Hyperplasia

An increase in the number of cells in a tissue or organ due to controlled cell division in response to increased demand or stimulation.

Hypertrophy

An increase in the size of individual cells (not the number), often seen in muscles due to exercise or cardiac cells due to high blood pressure.

Metaplasia

A reversible change in one adult cell type to another type due to chronic irritation/inflammation (e.g., squamous metaplasia in smokers’ respiratory epithelium).

Dysplasia

Abnormal growth/development of cells within a tissue; characterized by variation in cell size/shape and often considered precancerous.

Necrosis

Uncontrolled cell death due to irreversible damage (toxins, infection, ischemia), characterized by cell swelling, organelle dysfunction, and inflammation.

Leber’s Hereditary Optic Neuropathy (LHON)

A mitochondrial disease resulting from defects in mitochondrial function, leading to energy deficits affecting retinal ganglion cells and causing sudden vision loss.

Cystic Fibrosis (CF)

An endoplasmic reticulum-associated disease caused by a mutation in the CFTR gene, affecting chloride ion transport and leading to misfolding of the CFTR protein and thick mucus buildup.

Gaucher’s Disease

A lysosomal storage disease caused by a deficiency of the enzyme glucocerebrosidase, leading to the accumulation of undigested materials in lysosomes.

Epithelium

One of the four major tissue classes; lines surfaces and cavities, forms glands, is avascular, and includes parenchymal cells.

Connective Tissue

One of the four major tissue classes; the most abundant tissue type, providing structure and support, including fibrous, elastic, and reticular fibers (e.g., bone, blood, adipose tissue).

Muscle Tissue

One of the four major tissue classes; responsible for generating force and enabling movement, with three types: cardiac, skeletal, and smooth.

Nervous Tissue

One of the four major tissue classes; composed of neurons (transmit electrical signals) and glia (supporting cells).

Simple Squamous Epithelium

A single layer of flat cells, specialized for diffusion and filtration, found in the air sacs of lungs and lining of heart/blood vessels.

Simple Cuboidal Epithelium

A single layer of cube-shaped cells, specialized for secretion and absorption, found in secretory portions of small glands and kidney tubules.

Simple Columnar Epithelium

A single layer of tall, column-shaped cells, specialized for absorption and may secrete mucus/enzymes, found in the digestive tract.

Pseudostratified Columnar Epithelium

Appears to have multiple layers but is a single layer of cells of varying heights, typically secretory and ciliated, lining the upper respiratory tract (trachea).

Stratified Squamous Epithelium

Multiple layers of flat cells, providing protection against abrasion, lining the mouth, esophagus, and skin surface.

Transitional Epithelium

Specialized stratified epithelium that allows urinary organs (bladder, ureters) to expand and stretch to accommodate urine volume changes.

Collagen Fibers

Strong and flexible protein fibers (most abundant protein) found in connective tissue, providing tensile strength (e.g., in tendons/ligaments).

Elastic Fibers

Fibers in connective tissue that provide distensibility and flexibility, essential for organs like arteries to accommodate blood pressure changes.

Reticular Fibers

Fine collagenous fibers that form supporting networks (stroma) in soft organs like the spleen, lymph nodes, and kidneys.

Cardiac Muscle

Striated, branched, usually uninucleated muscle tissue found only in the heart walls (myocardium), under involuntary control.

Skeletal Muscle

Striated, tubular, multinucleated muscle tissue responsible for voluntary body movement.

Smooth Muscle

Non-striated, spindle-shaped, uninucleated muscle tissue that lines internal organs (e.g., intestines) and vessels, under involuntary control.

Neurons

Cells in nervous tissue that transmit electrical signals (nerve impulses).

Glial Cells (Neuroglia)

Supporting cells in nervous tissue that aid neurons, including astrocytes, oligodendrocytes, Schwann cells, microglia, and satellite cells.

Myelin Sheath

An insulating layer formed by Schwann cells (PNS) and oligodendrocytes (CNS) around axons, which speeds up nerve signal transmission.

Inflammation

A complex, essential, rapid, and coordinated tissue response to injury or infection, characterized by pain, warmth, swelling, and redness.

Polymorphonuclear Leukocytes (PMNs/Neutrophils)

First responders in acute inflammation; highly phagocytic cells that exit blood vessels to reach the injury site.

Cytokines

Chemical messengers (proteins) that amplify and regulate the inflammatory response, often released by immune cells.

Chemokines

A type of cytokine that acts as a chemoattractant, guiding leukocytes to the site of inflammation.

Histamine

A key mediator released by mast cells during inflammation, acting as a vasodilator and increasing vascular permeability.

Prostaglandins

Lipid mediators derived from arachidonic acid that coordinate inflammation, contributing to pain, fever, and vasodilation.

Bradykinin

A plasma-derived mediator that causes vasodilation and increased vascular permeability during inflammation.

Complement System

A cascade of 9 proteins in the blood plasma that are activated by antigen–antibody reactions and play a crucial role in immunity and inflammation.

Pattern Recognition Receptors (PRRs)

Receptors on immune cells that recognize PAMPs (pathogen-associated molecular patterns) and DAMPs (damage-associated molecular patterns), initiating an inflammatory response.

Cytokine Storm

An uncontrolled and excessive release of pro-inflammatory cytokines, which can lead to systemic inflammatory response syndrome (SIRS) and organ dysfunction.

Systemic Inflammatory Response Syndrome (SIRS)

A severe, generalized inflammatory state often triggered by a cytokine storm, potentially leading to organ failure.

Chronic Inflammation

Inflammation that fails to resolve, persisting over a long period and potentially leading to tissue damage, fibrosis, and organ dysfunction.