Histology

Tissues

Collections of similar cells that work together.

Fundamental tissues

Tissues that give rise to more specialized tissues, derived from embryonic germ layers (endoderm, mesoderm, ectoderm).

Epithelial tissue

Covers and lines surfaces in the body.

Connective tissue

Composed of widely spaced cells with an extracellular matrix; includes solid and liquid tissues.

Muscular tissue

Made up of contractile cells known as fibers.

Nervous tissue

Consists of neurons and supportive neuroglial cells.

Squamous cells

Flat, scale-like epithelial cells.

Cuboidal cells

Cube-shaped epithelial cells with spherical nuclei.

Columnar cells

Elongated epithelial cells with oval nuclei.

Simple layer

A single layer of epithelial cells.

Stratified layer

More than one layer of epithelial cells.

Extracellular matrix

Basement membrane containing collagen fibers that supports epithelial tissues.

Avascular

Lacking blood vessels, except in specific areas like the cochlear duct.

Tight junctions

Continuous bands of proteins that attach adjacent epithelial cells. (cell to cell)

Adherens junctions

Points of attachment between adjacent cells anchored by actin filaments.

Desmosomes

Strong "spot welds" that hold adjacent cells together under stress through intermediate filaments.

Gap junctions

Pores that allow communication between adjacent cells, important in cardiac muscle.

Hemidesmosomes

Junctions that anchor cells to the extracellular matrix.

Actin-linked cell-matrix junctions

Junctions that connect cells to the extracellular matrix via actin filaments.

Connective tissues

Include bone, cartilage, tendons, ligaments, blood, and adipose tissue.

Mesenchyme cells

Embryonic cells that give rise to connective tissues.

Vascularized

Presence of blood vessels, except in cartilage.

Bone tissue

Connective tissue that forms the skeleton.

Ligaments

Connective tissues that connect bone to bone.

Tendons

Connective tissues that attach muscle to bone or other tissues.

Adipose tissue

Fat tissue composed of adipocytes that store fats.

Muscle fibers

Contractile cells in muscular tissue.

Skeletal muscle

Voluntary muscle tissue, e.g., biceps brachii.

Smooth muscle

Involuntary muscle tissue found in the GI tract.

Cardiac muscle

Involuntary muscle tissue of the heart.

Contractile

Ability of muscle tissue to shorten by force.

Extensible

Ability of muscle tissue to stretch.

Excitable

Ability of muscle tissue to respond to nerve impulses.

Elastic

Ability of muscle tissue to return to original length after stretching.

Neurons

Nerve cells that conduct nerve impulses.

Neuroglial cells

Supportive cells in the nervous system that do not conduct impulses.

Acidic dyes

Negatively charged dyes that stain positively charged structures.

Eosin dye

Acidic dye that stains cytoplasmic proteins bright pink.

Basic dyes

Positively charged dyes that stain negatively charged structures like DNA.

Hematoxylin

Basic dye that stains nuclei dark blue to purple.

Vital stains

Stains used on living cells to observe physiological characteristics.

Wright's stain

A stain useful for differentiating blood cell types.

Janus green

Stains mitochondria in cells.

Neutral red

Stains lysosomes in cells.

What are the 3 characteristics of organizing epithelial tissues?

morphology, number of layers, and location

Describe squamous cells

flat, scale-like

Describe cuboidal cells

roughly cube shaped, usually possess a spherical nucleus

Describe columnar cells

elongated, thin along one axis; usually oval shaped nucleus. Nucleus will typically be toward base of cell

What are the typical origins of epithelial tissues

echo and endoderm. Mesothelial are not common. Mainly connective and ___

What is it called when there is more than one later of tissue

stratified

What is called when there is a single layer of tissue

simple

Define apical

“free surface”; exposed

What is the most abundant protein in tissues

collagen

What is an endocrine gland and what tissue does it come from

a gland that secretes products in to the blood stream and come from epithelial tissue. (thyroid and pituitary)

what are exocrine glands and what tissue do they specialize from

they secrete onto the surface of the skin and come from epithelial tissue. (salivary and sweat)

What are merocrine secretions

secretion through exocytosis (doesn’t damage cell). Eccrine sweat gland

what are holocrine secretions

secretion of entire cytoplasmic materials with remnants of dead cells. (exocrine)