Anatomy and Physiology - Tissues, Integumentary System, and Cellular Organization

Comprehensive vocabulary flashcards covering human anatomy and physiology topics including cell structure, membrane transport, tissues, tissue repair, and the integumentary system.

Cutaneous membrane

an organ composed of epidermis (avascular) and dermis (vascular)

Epidermis

The superficial, thin, avascular layer of skin composed of keratinized stratified squamous epithelium that functions in protection and reducing water loss.

Dermis

The deep, thick, vascular layer of skin composed of dense irregular connective tissue that provides strength, elasticity, and structural support.

Hypodermis

Also known as subcutaneous tissue; a layer deep to the skin containing loose connective tissue, adipose tissue, macrophages, and fibroblasts that functions in energy storage, insulation, and padding.

Keratinocyte

The most numerous cell type in the epidermis that produces and stores the protein keratin to provide hardness and waterproofing to hair, skin, and nails.

Melanocyte

A cell located in the stratum basale of the epidermis that produces melanin to determine hair and skin color and protect against UV radiation.

Merkel cell

in the epidermis involved in detecting light touch and superficial pressure, abundant in the hands and feet.

Langerhans cell

Also known as a dendritic cell; an epidermal cell that engulfs bacteria and foreign particles, functioning as a macrophage in immune responses.

Stratum basale

The deepest layer of the epidermis attached to the basement membrane, consisting of a single layer of cuboidal basal cells actively undergoing mitosis; cells take $40$ to $56$ days to reach the surface.

Stratum spinosum

An epidermal layer consisting of eight to ten layers of living keratinocytes held together by desmososomes, active in keratin production.

Stratum granulosum

An epidermal layer where cells flatten, develop thicker membranes, and undergo cell death, containing keratohyalin granules and keratin.

Stratum lucidum

A thin, clear zone of dead keratinocytes found exclusively in the thick skin of the palms, soles, and digits.

Stratum corneum

The most superficial epidermal layer composed of $15$ to $30$ layers of dead, keratinized cells that slough off and act as a protective barrier against microbes and dehydration.

Papillary dermis

The superficial portion of the dermis composed of loose connective tissue featuring dermal papillae, capillary nets, lymph vessels, and sensory neurons.

Reticular dermis

The thick, deep layer of the dermis composed of dense irregular connective tissue rich in collagen and elastin fibers, housing hair follicles, nerves, and glands.

Cleavage lines

Also called tension lines; the orientation of collagen and elastic fibers in the dermis, where parallel surgical incisions result in less scar tissue and faster healing.

Cyanosis

A bluish discoloration of the skin that occurs when tissue oxygen levels decline and unoxygenated hemoglobin makes superficial blood appear darker.

Erythema

Redness of the skin caused by increased blood flow through dilated superficial blood vessels.

Albinism

A genetic condition characterized by a complete absence of melanin production, resulting in pale hair, skin, and eyes.

Vitiligo

A skin disorder, likely autoimmune, characterized by the loss of pigment in patches due to melanocyte destruction.

Basal cell carcinoma

The most common type of skin cancer caused by UV radiation exposure, originating in the stratum basale and frequently affecting the head, neck, arms, and back.

Squamous cell carcinoma

A skin cancer originating in the keratinocytes of the stratum spinosum that presents as scaly lesions and is more likely to metastasize than basal cell carcinoma.

Melanoma

The most deadly form of skin cancer originating in melanocytes, characterized by asymmetric, border-irregular, multi-colored, evolving lesions greater than $6\text{ mm}$ in diameter.

Lanugo

Delicate, unpigmented hair covering a fetus in utero.

Vellus hair

Short, fine, unpigmented hair covering most of the adult body, commonly called peach fuzz.

Terminal hair

Long, coarse, pigmented hair found on the scalp, eyelids, eyebrows, and axillary regions.

Hair bulb

The expanded base of the hair root deep in the dermis containing the hair matrix and hair papilla for hair growth.

Arrector pili muscle

A smooth muscle attached to a hair follicle that contracts via sympathetic nervous stimulation to pull the hair shaft erect, creating goosebumps.

Eccrine sweat gland

The most common type of sudoriferous gland, coiling in the dermis with ducts opening directly to the skin surface, primarily responsible for thermoregulation.

Apocrine sweat gland

A sudoriferous gland located in the axillae and groin with ducts terminating on hair follicles, producing an odorless secretion that creates body odor when broken down by bacteria.

Sebaceous gland

An exocrine gland associated with hair follicles that secretes sebum to lubricate and waterproof hair and skin.

Ceruminous gland

A modified sweat gland located in the external ear canal that produces cerumen (earwax) to protect against foreign bodies, bacteria, and insects.

Nail matrix

The active growth region at the proximal nail root consisting of stratum basale cells that give rise to the nail body.

Calcitriol

The active form of Vitamin D3 converted by the kidneys after cholesterol in the skin is exposed to UV light to form cholecalciferol, which is modified in the liver.

Rule of Nines

A clinical system used to estimate the percentage of total body surface area affected by burns by dividing the body into specific anatomical regions assigned $9{\%}$ or multiples thereof.

Histology

The microscopic study of tissues and their extracellular substances.

Biopsy

A diagnostic method of extracting tissue from a living organism for microscopic examination.

Ectoderm

The outer embryonic germ layer that gives rise to the epidermis, skin glands, nervous system, pituitary gland, adrenal medulla, parts of the mouth, and the anus.

Mesoderm

The middle embryonic germ layer that gives rise to connective tissues proper, bone, cartilage, blood, blood vessel endothelium, muscle, synovial membranes, serous membranes, and kidneys.

Endoderm

The inner embryonic germ layer that gives rise to the epithelial lining of the airways, digestive tract, liver, pancreas, and thyroid.

Mucous membrane

A tissue membrane lining body cavities that open to the outside of the body, including the respiratory, digestive, and urinary tracts.

Serous membrane

A tissue membrane lining sealed internal body cavities (pleural, peritoneal, pericardial) that secretes lubricating serous fluid.

Synovial membrane

A connective tissue membrane lining joint cavities that secretes lubricating synovial fluid.

Tight junction

An intercellular connection that forms a tight, impermeable seal between adjacent plasma membranes to create a permeability barrier.

Gap junction

An intercellular connection containing protein channels (connexons) that permit the passage of ions and small molecules for direct intercellular communication.

Desmosome

An anchoring junction that mechanically binds adjacent cells together using transmembrane glycoproteins attached to intermediate filaments.

Hemidesmosome

An anchoring junction that attaches the basal surface of an epithelial cell to the underlying basement membrane.

Merocrine secretion

The most common mode of glandular secretion where products are released via exocytosis while leaving the secretory cell completely intact.

Apocrine secretion

A mode of glandular secretion where the apical portion of the cell pinches off containing the secretory product, after which the cell repairs itself.

Holocrine secretion

A mode of glandular secretion in which the entire cell ruptures and is destroyed to release its accumulated secretory contents.

Intercalated disk

A specialized junctional complex containing gap junctions and desmososomes that joins cardiomyocytes to synchronize electrical and mechanical activity in heart muscle.

Granulation tissue

The vascular, delicate connective tissue composed of proliferating fibroblasts formed during early tissue repair.

Carcinoma

A malignant cancer originating from epithelial tissues, such as lung, breast, colon, prostate, and skin cancers.

Sarcoma

A relatively rare cancer originating from non-epithelial tissues, such as connective tissue, bone, or muscle.

Selective permeability

The property of the plasma membrane that regulates the passage of substances, allowing only certain materials to cross passively or actively.

Membrane potential

The difference in electrical charge across the plasma membrane, resulting in a negatively charged intracellular environment relative to the extracellular fluid.

Fluid-mosaic model

The structural model describing the plasma membrane as a dynamic, non-rigid bilayer of phospholipids with embedded floating proteins, cholesterol, and carbohydrates.

Integral membrane protein

A protein embedded deeply within or spanning completely through the lipid bilayer of the plasma membrane.

Peripheral membrane protein

A protein bound to either the inner or outer surface of the plasma membrane lipid bilayer.

Ligand

A specific chemical messenger, such as a hormone or neurotransmitter, that binds to a receptor or gated channel protein to trigger a response.

Simple diffusion

The passive movement of small, nonpolar, lipid-soluble molecules directly through the lipid bilayer from higher to lower concentration without energy.

Facilitated diffusion

The passive transport of large, polar, or charged molecules across the plasma membrane down their concentration gradient using channel or carrier proteins without ATP.

Osmosis

The passive diffusion of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Tonicity

The ability of an extracellular fluid to move water into or out of a cell by osmosis, governed by solute concentrations.

Hypertonic solution

A solution with a higher solute concentration outside the cell than inside, causing water to leave the cell and leading to cell shrinkage.

Hypotonic solution

A solution with a lower solute concentration outside the cell than inside, causing water to enter the cell and leading to cell swelling or lysis.

Isotonic solution

A solution having equal solute concentration inside and outside the cell, resulting in no net movement of water.

Active transport

The movement of substances across a plasma membrane against their concentration gradient using carrier proteins and cellular energy ($\text{ATP}$).

Sodium-potassium pump

An ATP-powered transport protein that actively pumps $3\text{ Na}^+$ out of the cell and $2\text{ K}^+$ into the cell per ATP molecule to maintain membrane potential.

Phagocytosis

A form of endocytosis known as cell eating, where a cell extends processes to engulf large solid particles or microorganisms into a vesicle or vacuole.

Pinocytosis

A form of endocytosis known as cell drinking, where a cell takes in droplets of extracellular fluid containing solutes in small vesicles.

Exocytosis

A vesicular transport process where intracellular vesicles fuse with the plasma membrane to release materials out of the cell using energy.

Nucleolus

A dense, dark-staining region within the nucleus where ribosomal RNA ($\text{rRNA}$) is synthesized and assembled with proteins to form ribosome subunits.

Ribosome

A non-membranous organelle composed of rRNA and proteins that serves as the site of protein synthesis by linking amino acids.

Rough endoplasmic reticulum

A membranous network studded with ribosomes involved in synthesizing, modifying, and transporting proteins toward the Golgi apparatus.

Smooth endoplasmic reticulum

A membranous network lacking ribosomes that synthesizes lipids and steroid hormones, regulates intracellular calcium, and detoxifies chemicals.

Golgi apparatus

An organelle composed of flattened membranous sacs (cisternae) that sorts, modifies, packages, and ships proteins and lipids received from the rough ER.

Lysosome

A membrane-bound digestive organelle formed by the Golgi apparatus that contains hydrolytic enzymes to break down waste, foreign material, and worn-out organelles.

Autophagy

The cellular process of self-eating, where lysosomes digest and recycle a cell's own unneeded or damaged organelles.

Mitochondria

Double-membrane organelles with inner folds called cristae that act as the powerhouse of the cell by generating ATP through aerobic cellular respiration.

Peroxisome

A membrane-bound organelle containing enzymes for lipid metabolism and chemical detoxification that neutralizes free radicals.

Cytoskeleton

A dynamic network of protein fibers (microtubules, microfilaments, intermediate filaments) in the cytosol that provides structural support, cell motility, and intracellular transport.

Microtubules

Hollow protein cylinders made of tubulin dimers ($25\text{ nm}$ in diameter) that maintain cell shape, form spindle fibers during mitosis, and form cilia and flagella.

Transcription

The first step of protein synthesis taking place in the nucleus, where RNA polymerase constructs an mRNA transcript complementary to a DNA gene sequence.

Translation

The second step of protein synthesis taking place at the ribosome in the cytoplasm, where mRNA codons are decoded by tRNA anticodons to assemble amino acids into a polypeptide chain.

Codon

A three-nucleotide sequence on an mRNA strand that specifies a particular amino acid during translation.

Anticodon

A three-nucleotide sequence on a tRNA molecule that pairs complementarily with a specific mRNA codon.

Interphase

The long phase of the cell cycle between divisions where routine metabolism occurs and DNA is replicated during the S phase.

Mitosis

The division of the cell nucleus consisting of prophase, metaphase, anaphase, and telophase, resulting in two identical nuclei.

Cytokinesis

The division of the cytoplasm following mitosis that completes the physical separation into two distinct daughter cells.

Apoptosis

Programmed cell death that regulates cell numbers and eliminates virus-infected, damaged, or cancerous cells.