Histology: The Study of Tissues

Flashcards covering the four major tissue types (epithelium, connective, muscle, nervous), their classifications, functions, specific types, and key components as presented in the lecture notes.

HISTOLOGY

The Study of Tissues

Tissue

A group of similar cells with a common function

Epithelium

Layer(s) of tightly connected cells lining a surface

Connective tissue

Cells scattered in a matrix

Muscle tissue

Rope-like or in the wall of a hollow organ; contracts

Nervous tissue

Star-shaped cell body with dendrites and axons; sends impulses

Basement membrane

Barrier that joins deep epithelial cells and underlying cells

Simple (Epithelium classification)

Consists of one layer of cells

Stratified (Epithelium classification)

Consists of many layers of cells

Pseudostratified (Epithelium classification)

Falsely layered appearance (one row of asymmetric cells)

Squamous (Cell shape)

Flattened, scale-like cell shape

Cuboidal (Cell shape)

Cube-shaped cell shape

Columnar (Cell shape)

Rectangle-shaped cell shape

Pseudostratified Columnar Epithelium

Characterized by one row of asymmetric cells, giving a falsely layered appearance; found in the Trachea

Simple epithelium function

Selectively permeable barrier, transport, diffusion (O2, CO2), blood filtration, nutrient absorption, secretion (gland products)

Cilia

Hair-like projections that lubricate and remove debris

Stratified Epithelium function

Protective barrier against abrasion, dehydration, germs, and chemicals; cells are rapidly replaced by mitosis

Simple Cuboidal Epithelium

One layer of cube-shaped cells; found in glands and ducts

Simple Squamous Epithelium

One layer of flattened cells; found in serous membranes, lung air sacs (alveoli), capillaries, and kidneys

Stratified Squamous Epithelium

Many layers of flat cells that protect against abrasion in skin, cornea, mouth, throat, esophagus, vagina, and rectum

Keratinized Stratified Squamous Epithelium

Stratified squamous epithelium with exposed dead surface cells filled with keratin, providing protection and waterproofing (e.g., skin)

Simple Columnar Epithelium

Single layer of rectangle-shaped cells lining digestive and reproductive tracts

Goblet cells

Vase-shaped cells in simple columnar epithelium that make mucus for lubrication and trapping debris

Microvilli

Smallest hair-like projections in the digestive tract that increase surface area for absorption

Transitional Epithelium

Layers of spherical or cuboidal-shaped cells in the empty urinary bladder that stretch and thin out when the bladder is full

Serous membranes (Serosa)

Simple squamous epithelium lining internal closed body cavities

Visceral membrane

A serous membrane that envelopes an organ

Parietal membrane

A serous membrane that lines a body cavity

Pleura

Serous membranes associated with the lungs and chest (thorax)

Pericardium

Serous membranes associated with the heart

Peritoneum

Serous membranes associated with the abdominopelvic cavity and organs

Retroperitoneal

Located behind the peritoneum (e.g., kidneys)

Pneumothorax

Air between pleural membranes, leading to a collapsed lung

Connective tissue (CT)

Tissue with specialized cells scattered in an extracellular matrix, providing diverse functions like support, connection, protection, insulation, and transport

Matrix (Connective Tissue)

Material surrounding the cells in connective tissue, composed of fibers and ground substance

Ground substance

The fluid, semisolid, or solid material component of the connective tissue matrix

Osteocyte

A mature bone cell

Chondrocyte

A mature cartilage cell

Erythrocyte

Red blood cell

Leukocyte

White blood cell

Thrombocyte

Platelet

Adipocyte

A fat cell

Loose (areolar) Connective Tissue

Characterized by loosely arranged fibers that support and connect other tissues/organs; often contains interstitial fluid

Edema

Excess water in the interstitial fluid of loose connective tissue

Dense Regular Connective Tissue

Tightly packed unidirectional collagen fibers that provide tensile strength; found in tendons and ligaments

Tendon

A type of dense regular connective tissue that attaches muscle to bone

Ligament

A type of dense regular connective tissue that attaches bone to bone

Dense Irregular Connective Tissue

Tightly packed multidirectional fibers that provide strength and withstand tension from many directions; found in skin dermis, fascia, and joint capsules

Dense Elastic Connective Tissue

Contains elastic fibers for durability, stretch, and recoil; found in the aorta and respiratory tract

Cartilage

A firm gel, water-packed matrix tissue with chondrocytes located in lacunae; lacks blood vessels, leading to slower healing

Lacunae

Small spaces within cartilage (and bone) where chondrocytes (and osteocytes) reside

Hyaline cartilage

Cartilage with a 'glassy' matrix that provides stiff, flexible support and protection; found in the nose, respiratory tract, rib cartilages, embryonic skeleton, and joint bone ends

Elastic Cartilage

Cartilage containing elastic fibers for flexible support; can distort and return to its original shape; found in the ear and epiglottis

Fibrocartilage

Cartilage made of tough, dense collagen fibers, resisting compression and preventing bone-to-bone contact; found in knee menisci and vertebral discs

Bone (Osseous tissue)

Tissue with a hard mineralized matrix encircling a central canal, containing osteocytes in lacunae; functions include support, protection, movement, mineral/fat storage, and blood production

Lamellae

Hard mineralized layers arranged concentrically (like tree rings) in bone tissue

Adipose (fat cells)

Tissue resembling honeycomb, functioning in stored energy, insulation, support, and protection; found under the skin, breasts, around eyes/organs, yellow bone marrow, and joints

Blood

A connective tissue with a transparent plasma matrix, transporting nutrients, wastes, hormones, etc.

Plasma

The transparent liquid matrix component of blood

Red Blood Cells (Erythrocytes)

Most numerous blood cells, biconcave disc shape, no nucleus, primarily responsible for carrying oxygen

White Blood Cells (Leukocytes)

Fewest blood cells, largest in size, with a large, oddly shaped nucleus; identify and kill germs

Platelets (Thrombocytes)

Smallest blood components, irregular fragments that function in blood clotting

Crenated cell

A cell that has shrunk due to water moving out into a hypertonic surrounding plasma

Skeletal muscle

Muscle tissue attached to and moving bones, also found in facial expressions and eyes; exhibits voluntary movement

Cardiac muscle

Muscle tissue found only in the heart, responsible for pumping blood; exhibits involuntary movement

Smooth muscle

Muscle tissue found in the walls of hollow organs, contracting to squeeze material within; exhibits involuntary movement

Actin and Myosin

Tiny rope-like proteins within muscle cells that slide past each other to shorten the entire muscle cell, enabling contraction

Skeletal Muscle (cellular features)

Largest cylindrical cells with perpendicular pink stripes (striations) and multiple large, flat peripheral nuclei; enables voluntary movement

Intercalated disc

Specialized junction in cardiac muscle cells that helps them contract in a coordinated way for normal blood flow

Smooth Muscle (cellular features)

Toothpick-shaped cells with a large oval central nucleus and no striations; found in hollow organ walls

Neuron

A star-shaped nervous tissue cell (with cell body, dendrites, and axon) that receives and sends electrical messages, monitoring and controlling the body

Dendrites

Short, branching extensions of a neuron that receive electrical messages

Axon

A long, typically single extension of a neuron that sends electrical messages

Neuroglia (glial cells)

Support cells for neurons, providing physical support, protection, insulation, chemical homeostasis, nutrient supply, and infection prevention