Histology::the study of tissues

4 types of tissues:: Epithelial Connective Muscular Neural

Epithelial tissue::avascular sheet of cells that covers body surfaces or cavities

2 main forms of epithelial tissue:: Covering and lining epithelia (skin), Glandular epithelia (salivary glands)

Microvilli::Abundant on transport cells Dramatically increase surface area Found in intestinal lining, kidneys

Cilia::Beat in coordinated fashion Move fluid along surface Found in trachea, oviduct

Characteristics of epithelial tissues::Tightly packed (barrier, absorption/secretion, hemidesmosomes, desmosomes) Organized assembly (apical/basolateral surface, surfaces differ in function) Exhibit polarity (necessary for selective movement of molecules) Highly regenerative (often damaged)

Simple::single layer of cells

Stratified::2 or more layers of cells

Pseudostratified::single layer of cells that appears as more due to nuclei placement

Squamous::flat, scale-like

Cuboidal::box-like

Columnar::tall, rectangular-shaped

Simple Squamous::single layer of flat, disc-like cells flattened nuclei surface for filtration and diffusion located in: air sacs of lung, glomeruli, blood vessel/capillary lumens, body cavity linings

Simple Cuboidal::single layer of cube-like cells large, round nuclei responsible for secretion and absorption located in: ducts and glands, kidney tubules, ovary, thyroid

Simple Columnar::single layer of tall, rectangular cells elongated nuclei microvilli (absorption) and cilia (propulsion) common on apical surface function in absorption (digestive tract) and secretion (mucous, reproduction) located in: digestive tract lining, respiratory tract

Pseudostratified Columnar::single layer of columnar cells of different heights nuclei appear at different heights have appearance of multiple layers function in secretion and propulsion located in: male sperm duct, respiratory tract, large glands

Stratified Squamous::multiple layers of squamous cells on a basement membrane surface cells are dead, flat, and keratinized basal cells are cube-shaped and mitotically active form protection against abrasion and damage for tissue underneath located in: skin, lining of esophagus, lining of vagina, lining of mouth

Stratified Cuboidal/Columnar::Two or more layers of cuboidal or columnar cells Function in secretion located in: male sperm duct, sweat and mammary glands, pharnyx, male urethra

Transitional::Appears to be stratified squamous or cuboidal Basal cells are cuboidal Surface cells are rounded/squamous Stretch permitted, enabling storage of urine located in: ureter, bladder, urethra

Endocrine::Secrete hormones into local capillaries Exocrine = Secrete their product into a duct

Merocrine::Product secreted directly through plasma membrane by exocytosis

Apocrine::Product secreted by pinching off membrane, loss of cytoplasm

Holocrine::Product secreted by full cell rupturing

Connective Tissue Proper::Loose (Fibers create loose, open framework) & Dense (Fibers densely packed)

Fluid Connective Tissues::Blood (Contained in cardiovascular system) Lymph (Contained in lymphatic system)

Supporting Connective Tissues::Cartilage (Solid, rubbery matrix) Bone (Solid, crystalline matrix)

Osteoblasts/cytes::bone fibers

Fibroblasts/cytes::connective tissue proper fibers

Chondroblasts/cytes:: cartilage fibers

Adipocytes::fat tissue fibers

Blood Cells::immunity fibers

Collagen::abundant, cross-linked fibrils, rope-like, resist tension

Elastin::long/branched, can stretch/recoil, provides flexibility

Reticulin::short/thin, mesh-like, provide greater degree of movement than collagen

Characteristics of Connective Tissues::Protection, Structural Support Energy, Storage, Insulation Transporting Substances

Areolar::Loosely packed assembly of all fiber types, fibroblasts and immune cells, cushions organs, key immune mediators located in: support under epithelial layers and surrounding organs

Adipose::matrix crowded by tightly-packed adipocytes, serves to insulate and protect organs, provides energy storage depot located in: around major organs, within subcutaneous layer (under dermis)

Regular Dense Connective Tissue::Fibroblasts embedded within regularly-ordered assembly of collagen fibers, resists pulling stress located in: attaches muscles to bone (tendon), attaches bone to bone (ligament) Irregular Dense Connective Tissue::Irregularly-arranged collagen fibers with fibroblasts embedded within, resists force in many directions located in: dermis, joint capsules

Elastic Dense regular connective tissue::enriched with elastin fibers, ordered arrangement of elastin, allows for stretch and recoil of tissue located in: walls of arteries, walls of bronchial tubes

Blood::Erythrocytes, leukocytes and platelets within a plasma matrix, transports oxygen, CO2, nutrients and other dissolved molecules throughout the body located in: arteries, veins and capillaries

Hyaline::flexible, firm gel secreted by chondroblasts, embedded in lacunae, cushions supports and reinforces other tissues and organs located in: nose, trachea, ribs, ends of long bones, embryonic skeleton

Elastic::enriched with elastin, has higher flexibility and stretch, allows for tissue to return to original shape located in: outer ear, epiglottis

Fibrocartilage::Firm hyaline matrix, with more organized collagen fibers, resists compressive force located in: components of joints with limited flexibility, menisci, public symphysis

Bone::calcified collagen matrix with embedded osteocytes, high degree of vascularity, calcium storage, attachment for muscles, spongy bone contains marrow, stem cells for blood information located in: skeleton Muscle Tissue::capable of contraction/shortening

3 types of Muscular Tissue::skeletal, cardiac, smooth

Skeletal Muscle::controlled by voluntary nervous system, moves and stabilizes the skeleton, contains elongated cells (fibers held together by loose connective tissue, contains many nuclei, possesses microscopic striations)

Cardiac Muscle::only in heart, short/branched fibers, single nucleus, striated, involuntary contraction

Smooth Muscle::short/tapering cells, no striation, involuntary contraction changes diameter of vessels/chambers (blood vessels, urinary bladder, digestive organs, uterus)

Nervous Tissue::Conduct electrical impulses, transfer process and store information, comprised of neurons and glial cells

3 parts of Nervous Tissue::Neurons, Glial Cells Location

Neurons::receive sensory information and carry it to the brain, transmit motor impulses from brain to effector organs, form synapses with one another

Glial Cells::provide structural support, protection and nourishment for neurons in the brain and spinal cord

Location of Nervous Tissue::brain, spinal cord, cranial and peripheral nerves