Body Tissues, Integumentary System, and Cell Structures

A complete set of vocabulary flashcards covering tissues, histology, integumentary structures, cell organelles, chemical bonding, and cellular transport mechanisms.

Tissue

A group of cells with similar structure and function.

Histology

The scientific study of tissues.

Epithelial Tissue

A primary body tissue class composed of layers of closely spaced cells that cover organ surfaces, line cavities, and serve for protection, secretion, and absorption.

Connective Tissue

A primary body tissue class with more extracellular matrix than cell volume, specialized to protect, support, and bind body tissues together.

Muscular Tissue

Tissue composed of elongated, excitable cells specialized for contraction and movement.

Nervous Tissue

Tissue containing excitable cells specialized for receiving stimuli and rapidly conducting coded electrical impulses to other cells.

Avascular

The characteristic of lacking direct blood vessels, as seen in epithelial tissue.

Simple Epithelium

An epithelial tissue classification consisting of a single layer of cells.

Stratified Epithelium

An epithelial tissue classification consisting of more than one layer of cells.

Pseudostratified Epithelium

An epithelial tissue that has a single layer of cells but appears to have two or more layers because the nuclei are located at different levels.

Transitional Epithelium

A specialized stratified epithelium that can be greatly stretched, appearing cuboidal when unstretched and squamous when stretched by fluid.

Endocrine Glands

Glands that lack ducts and secrete hormones directly into the blood.

Exocrine Glands

Glands containing ducts through which secretions are released onto a surface or into a body cavity.

Merocrine Secretion

A mode of exocrine secretion where products are released with no loss of cellular material, such as in sweat glands.

Apocrine Secretion

A mode of exocrine secretion where a portion of the cell pinches off with the secretion, such as in mammary glands.

Holocrine Secretion

A mode of exocrine secretion where the entire cell is shed during secretion, such as in sebaceous glands.

Proteoglycans

Molecules in the ground substance of connective tissue matrix that hold water, allowing tissues to return to their original shape after compression.

Loose (Areolar) Connective Tissue

Connective tissue that serves as the loose packing material of the body, filling spaces between organs and holding them in place.

Compact Bone

Strong, dense bone tissue with more matrix than spaces, organized into functional units called Haversian systems or osteons.

Cancellous Bone

Bone tissue with more spaces than matrix, composed of interconnecting plates called trabeculae; also known as spongy bone.

Skeletal Muscle

Voluntary, striated muscle tissue containing large, multinucleated cylindrical cells attached to bones that make body movement possible.

Cardiac Muscle

Involuntary, striated muscle tissue found in the heart, consisting of branched cells with a single central nucleus connected by intercalated disks.

Smooth Muscle

Involuntary, non-striated muscle tissue with single-nucleus tapered cells found in the walls of hollow organs, skin, and eyes.

Intercalated Disks

Specialized cell-to-cell junctions containing gap junctions that connect cardiac muscle cells together.

Action Potential

Electrical signals used by nervous tissue cells to communicate with one another and with other tissue cells.

Neurons

The functional nerve cells responsible for conducting action potentials in nervous tissue.

Neuroglia

Support cells of the nervous tissue that function to nourish, protect, and insulate neurons.

Mucous Membranes

Membranes lining body cavities that open to the outside environment, containing glands that secrete mucus.

Serous Membranes

Membranes lining closed internal trunk cavities that do not open to the outside, lacking glands and secreting serous fluid.

Synovial Membranes

Membranes that line freely movable body joints.

Mediators of Inflammation

Chemical substances released or activated in injured tissues and blood vessels following damage, including histamine, kinins, prostaglandins, and leukotrienes.

Labile Cells

Cells that divide continuously throughout life and readily undergo regeneration.

Stable Cells

Cells that do not ordinarily divide but retain the capacity to regenerate if injured, such as liver and pancreas cells.

Permanent Cells

Cells with little or no ability to divide that are repaired strictly by replacement if destroyed, such as neurons and skeletal muscle cells.

Regeneration

A type of tissue repair where new cells are of the same type as those destroyed, fully restoring normal tissue function.

Replacement

A type of tissue repair where a new type of tissue develops, leading to scar production and loss of some tissue function.

Epidermis

The outermost layer of the skin, composed of stratified squamous epithelium resting on the dermis.

Keratinization

The process occurring as epidermal cells move from the stratum basale toward the surface, filling with the protein keratin to make the cells hard.

Stratum Basale

The deepest layer of the epidermis, consisting of cuboidal or columnar cells that undergo mitotic division every $19\text{ days}$.

Stratum Corneum

The most superficial layer of the epidermis, composed of dead, flattened squamous cells filled with keratin.

Melanocytes

Cells located in the deepest epidermal layers that produce the pigment melanin inside melanosomes.

Langerhans Cells

Epidermal macrophages located in the stratum spinosum that assist in activating the immune system.

Merkel Cells

Epidermal touch receptors located in the stratum basale associated with sensory nerve endings.

Proprioception

The awareness of body position and motion in space.

Rule of Nines

A diagnostic guideline that estimates burn severity by dividing the total body surface area into sections representing approximately $9\%$ or multiples of $9\%$.

Callus

An abnormal thickening of the stratum corneum caused by continuous friction.

Alopecia

The partial or complete loss of hair.

Malignant Melanoma

The deadliest form of skin cancer arising from melanocytes, characterized by a high metastatic rate and evaluated using ABCDE clinical features.

Matter

Anything that occupies space and has mass.

Mass

The quantity of matter in an object, measured internationally in kilograms ($\text{kg}$).

Weight

The gravitational force exerted on an object of a given mass.

Atom

The smallest particle of an element that retains the chemical characteristics of that element.

Isotopes

Atoms of the same element containing the same number of protons and electrons but a different number of neutrons.

Valence Shell

The outermost electron shell of an atom.

Octet Rule

The chemical rule stating that atoms combine by transferring or sharing electrons to achieve $8$ electrons in their valence shell.

Ionic Bonding

A chemical bond formed when valence electrons are transferred between atoms, creating oppositely charged ions.

Covalent Bonding

A chemical bond formed when atoms with similar electronegativity share pairs of electrons.

Electronegativity

The measure of the ability of an atom's nucleus to pull electrons toward itself.

Electrolytes

Solutions or substances containing charged ions that have the capacity to conduct electrical currents.

Anabolism

The collective synthesis reactions in the body that combine smaller reactants into larger, more complex products.

Catabolism

The collective decomposition reactions in the body that break down complex reactants into smaller, less complex products.

Enzyme

A protein catalyst that increases the rate of chemical reactions without being consumed or permanently changed.

Acid

A proton donor that increases the hydrogen ion ($H^+$) concentration of a solution relative to hydroxide ions ($OH^-$).

Base

A proton acceptor that lowers the hydrogen ion ($H^+$) concentration of a solution relative to hydroxide ions ($OH^-$).

Acidosis

A pathological condition resulting from blood pH dropping below $7.35$, leading to nervous system depression and potential coma.

Alkalosis

A pathological condition resulting from blood pH rising above $7.45$, leading to nervous system overexcitability and convulsions.

Buffers

Chemicals that resist changes in solution pH when either an acid or a base is added.

Monosaccharide

A simple sugar unit that serves as the primary building block of carbohydrates.

Glycogen

A polysaccharide that serves as the primary storage form of glucose in animals.

Plasma Membrane

The outer lipid bilayer boundary of a cell that regulates the passage of substances in and out of the intracellular space.

Simple Diffusion

The passive movement of solute particles from an area of higher concentration to an area of lower concentration without cellular energy expenditure.

Facilitated Diffusion

Carrier-mediated transport of substances across a membrane down their concentration gradient using specific protein channels without using ATP.

Osmosis

The passive movement of fluid across a semi-permeable membrane from low osmotic pressure to high osmotic pressure.

Hypertonic Solution

A solution with a higher concentration of solutes than the cytoplasm, causing water to leave the cell and the cell to shrink.

Hypotonic Solution

A solution with a lower concentration of solutes than the cytoplasm, causing water to enter the cell and the cell to swell or burst.

Phagocytosis

A form of active endocytosis termed cell-eating, where solid particles are ingested into membrane-bound vesicles.

Pinocytosis

A form of active endocytosis termed cell-drinking, where liquid vesicles are internalized by the cell.

Rough Endoplasmic Reticulum

An organelle with attached ribosomes on its outer surface that functions as a primary site of protein synthesis.

Smooth Endoplasmic Reticulum

An organelle lacking attached ribosomes that functions in lipid and steroid synthesis, lipogenesis, and cellular chemical detoxification.

Golgi Apparatus

A system of flattened membrane-bound sacs that collects, modifies, packages, and distributes proteins and lipids synthesized in the endoplasmic reticulum.

Lysosome

A membrane-bound vesicle containing hydrolytic enzymes (lysozymes) that digests phagocytized cellular debris and mediates apoptosis.

Mitochondria

The powerhouse organelle of the cell featuring inner cristae, which serves as the major site of ATP generation and the Citric Acid Cycle.

Karyolysis

A nuclear change during apoptosis characterized by the complete dissolution of the nucleus.

Pyknosis

A nuclear change during apoptosis characterized by nuclear shrinkage and condensation of chromatin.

Karyorrhexis

A nuclear change during apoptosis characterized by fragmentation of the nucleus and disintegration of chromatin.

Codon

A specific sequence of three consecutive nucleotides in mRNA that specifies a single amino acid.

Cytokinesis

The division of the cell cytoplasm into two separate cells during the final phase of cell division.

Apoptosis

Regulated, programmed cell death where the cell breaks into apoptotic bodies that are phagocytosed without triggering tissue inflammation.