Ch. 2-3 - cells, tissues, chemistry

Epithelial tissue

• Functions: covering/lining surfaces, glands

• Close together, usually gap junctions

• Innervated, no blood supply (usually needs to be connected to connective tissue via basement membrane)

Epithelial tissue classifications:

Simple squamous

• One row, flattened shape

• Facilitates diffusion (eg. O2 in lungs, serous fluid)

• Air sacs in lungs, lining heart, lymph vessels, serous membranes

Epithelial tissue classifications:

Simple cuboidal

• One row, square shape (w/ nucleus in center)

• Excretion and absorption

• Various small glands, ducts, kidney tubules

Epithelial tissue classifications:

Simple columnar

• One row, rectangular shape (w/ nucleus closer to basement membrane)

• Excretion and absorption

• GI tract, bladder (smooth), uterus, bronchioles (ciliated)

  • Can have microvilli on apical surface for absorption

Epithelial tissue classifications:

Pseudostratified columnar / PCCE

• Protection, secretion of mucous, movement of substances across membrane

• Lines most portions of upper respiratory tract, typically cilliated

Epithelial tissue classifications:

Stratified squamous

• Protection against abrasion, preventing water loss (in squamous cells with keratin)

• Lines esophagus, mouth, vagina, skin

Epithelial tissue classifications:

Stratified cuboidal

• Protection

• Not common, found in ducts of sweat glands + mammary glands

Epithelial tissue classifications:

Stratified columnar

• Secretion and protection

• Also uncommon, found in urethrae and ducts of some glands

Epithelial tissue classifications:

Transitional epithelium

• Allows expansion and stretching

• Urinary bladder, ureters

Types of glandular epithelial tissue

• Endocrine

  • Secretes into tissues/bloodstream

• Exocrine

  • Infolded, secretes several molecules out of body/into a compartment (eg. sweat)

Connective tissue

• Sparsely packed, provide support, protection, energy storage, pathogen defense

• Consist of tissue cell + extracellular protein fibers + ground substances (gel-like substance btwn cells + fiber)

-blast / immature cell, -cyte / mature cell

Connective tissue types

• Connective tissue proper (have visible fibers)

  • Loose

    • Areolar

    • Adipose

    • Reticular

  • Dense

    • Dense reg

    • Dense irregular

    • Elastic

• Fluid connective tissues

• Supportive connective tissues

  • Bone

  • Cartilage

    • Hyaline

    • Fibrocartilage

    • Elastic

Connective tissue proper: loose - areolar

• Collagen + elastic fibers

• Mostly ground substance, stretches and provides scaffolding for vessels

• Between the top and underlying skin layers, connects to epithelial tissues (lamina propria)

Connective tissue proper: loose - adipose

• Has collagen, elastic + reticular fibers with adipocytes (fat cells)

• “packing” material, storage, protection

• Surrounds organs susceptible to shock/jarring

  • Heart, behind eyeballs, distributed in buttocks/breasts/etc

Connective tissue proper: loose - reticular

• Reticular fibers

• Provides framework for cells + organs

Connective tissue proper: dense

*More collagen than loose and has greater stretch rest.

Regular

• Run parallel + resist tensile strength in one direction, has collagen

• Eg. tendons/ligaments

Irregular

• Meshwork of collagen in diff. directions to resist being pulled in various directions

• Eg. dermis, surrounding bones + cartilage + joints

Elastic

• Densely packed elastic fiber to allow for more movement

• Eg. elastic ligaments in vertebral column

Supportive connective tissues: bone

• Dense ground matrix with calcium crystals covering collagen (osteoid)

  • Osteocytes live in lacuna (pockets) within hardened osteoid

• Can be spongey or compact

Supportive connective tissue: cartilage

• Only avascular connective tissue

Hyaline

• Most common: clear appearance, scattered chondrocytes

• In nose/trachea/larynx/ribs/ends of long bones

Fibrocartilage

• Dense, weight/shock absorbing with more numerous collagen in matrix

• In vertebral discs, knees + joints, connect L+R pubic bones

Elastic cartilage

• Flexible, less collagen in matrix, more elastic fibers

• In external ear + epiglottis

Types of muscular tissue

Skeletal

• Striated, multinucleated, voluntary. Thin, cylindrical fiber-like shape

Cardiac

• Striated, uninucleate, involuntary. Only in heart. Branched structure

Smooth

• Nonstriated, uninucleate, involuntary. Automatic movements eg. GI, respiratory, reproductive tracts, pupils. Spindle-shaped

Nervous tissue

• Neuron consists of a soma (body) with dendrites branching out and an axon

  • Electrical signals travel down axon to communicate with other cells

• Maintained + held together by glial cells

Lamina propria

Areolar connective tissue that serves as the underlying layer to epithelial tissue and provides it with a blood supply in mucosal membranes

Mucous membranes

• Lines areas exposed to outside (eg. digestive, respiratory, urinary, reproductive tracts)

• Absorption + secretion

• Has goblet cells + multicellular glands that secret mucus

  • Mucin glycoprotein combined with water

• Lamina propria

Serous membranes

• Lines cavities not exposed to protect organs (eg. peritoneal, pleural, pericardiac)

  • Recall: folds to protect organs (visceral + parietal)

• Made of simple squamous epithelium that secretes serous fluid

Synovial membranes

• Lines joint cavities and produces synovial fluid to nourish cartilage and allow ease of movement

• Made of areolar connective tissue, not epithelium

Cutaneous membrane

• Skin / integument

• Keratinized stratified squamous epithelial cells + connective tissue (dermis)

• Largest sensory organ, covers body surface, protects + prevents water loss