Ch. 4 Anatomy Lecture

Tissue

A group of similar cells specialized to perform a specific function

What are the 4 types of tissues?

Epithelial, connective, muscle, and neural tissue

Epithelial tissue

• Cover surfaces, line spaces and passageways, and form glands

• Function: form protective barriers, control permeability (diffusion), produce specialized secretions

• Composed of tightly packed cells with little extracellular material

• Attachment between cells and to a common base (basement membrane)

• Cells may be specialized

• Exhibits polarity

• Avascular (no blood vessels)

• Can regenerate

Apical surface

• Free/top surface

• May have modifications: cilia or microvilli

Basal surface

Fixed/bottom surface

Simple epithelium

One layer of cells

Stratified epithelium

2 or more layers of cells

Pseudostratified epithelium

Appears stratified but is actually one layer of cells

Squamous cells

Flattened cells

Cuboidal cells

Square-like cells

Columnar cells

Rectangular-like cells

What type of tissue?

• Simple squamous epithelium

• Location: air sacs in lungs (alveoli), lining of heart chambers and lumen of blood vessels (endothelium), serous membranes of body cavities (mesothelium), portions of kidney tubules, and inner lining of cornea

What type of tissue?

• Simple cuboidal epithelium

• Location: kidney tubules, thyroid gland follicles, ducts and glands, and surface of ovary

What type of tissue?

• Non-ciliated simple columnar epithelium

• Apical surface has microvilli

• May contain goblet cells

• Location: lining of most of the digestive tract (lining of stomach does not contain goblet cells)

What type of tissue?

• Ciliated simple columnar epithelium

• May contain goblet cells

• Location: lining of uterine tubes and larger bronchioles of respiratory tract

What type of tissue?

• Ciliated pseudostratified columnar epithelium

• Contains goblet cells

• Location: lines most of respiratory tract (nasal cavity, pharynx, larynx, trachea, and bronchi) and portions of male reproductive tract

What type of tissue?

• Keratinized stratified squamous epithelium

• Basal cells are typically cuboidal

• Superficial cells are dead and filled with protein

• Location: epidermis of skin

What type of tissue?

• Non-keratinized stratified squamous epithelium

• Basal cells are typically cuboidal

• Superficial cells are alive and moist

• Location: lining of vagina, oral cavity, pharynx, esophagus, and anus

What type of tissue?

• Transitional epithelium

• Can look squamous or cuboidal

• Contain binucleated cells

• Location: Lining of urinary bladder, ureters, and urinary bladder

Gland

• Collection of epithelial cells that produce a secretion

• 2 types: endocrine and exocrine

Exocrine glands

• Release secretions via ducts (tubular passageways) onto the surface of epithelial tissue

• 3 types: serous (watery secretion → sweat), mucous (slimy secretion that contains mucin protein), and mixed glands (both serous and mucous secretion → saliva)

• Can be unicellular (goblet cells) or multicellular

Connective tissues

• Fill internal spaces, support other tissues, transport materials, store lipids

• Contain more extracellular materials than epithelial tissues

• Not exposed to the outside environment

• Components: specialized cells, extracellular protein fibers, and ground substance

• 3 types: connective tissue proper, supporting connective tissue, and fluid connective tissue

• Ex. Blood and bones

Ground substance

• Substance produced by the cells themselves in connective tissues

• Ex. the ground substance of blood is plasma

Matrix

• A combination of ground substance and protein fibers

• Non-cellular components of connective tissue

Connective tissue proper

• Connect other tissues together, protect organs, and store lipids

• Found all over the body

• 2 types: loose and dense

• Contains a variety of cell types: fibroblasts, macrophages, mast cells, and leukocytes

• Contains a variety of protein fibers: collagen, elastic, reticular

Loose connective tissue proper

• Fills spaces between organs and surrounds, stabilizes, and cushions organs

• Lots of ground substance (syrupy semi-fluid)

• Squishy and pliable

• 3 types: areolar, adipose, and reticular connective tissue proper

What type of tissue?

• Areolar connective tissue proper

• Contains multiple types of protein fibers scattered throughout: collagen, elastin, and reticular protein fibers

• Contains a variety of different cells scattered throughout

• Location: surrounds nerves, vessels, and organs, and the subcutaneous layer (between skin and underlying muscle)

What type of tissue?

• Adipose connective tissue proper

• Consists mostly of adipocytes (fat cells)

• Used for energy storage and for cushioning or packing material

• Location: around organs and subcutaneous layer

What type of tissue?

• Reticular connective tissue proper

• Used to make the framework of delicate organs

• Ex. organs in the lymphatic system (spleen, thymus, and lymph nodes) and bone marrow

Dense connective tissue proper

• Mostly protein fibers

• Tough

• 3 types: dense regular, dense irregular, and elastic connective tissue proper

What type of tissue?

• Regular connective tissue proper

• Fibers run parallel

• Mostly collagen protein

• Tough

• Ex. tendons and ligaments

What type of tissue?

• Irregular connective tissue proper

• Mostly collagen protein

• Fibers bundled in a random, mesh-like arrangement

• Ex. dermis of the skin

What type of tissue?

• Elastic connective tissue proper

• Mostly elastic fibers

• Somewhat parallel, but branching arrangement

• Ex. Elastic connections of vertebral spinous processes

Fibroblasts

Produce protein fibers and ground substance

Macrophages

Phagocytize foreign materials

Mast cells

Release histamine and heparin to stimulate local inflammation

Plasma cells

Form antibodies

Lymphocytes

Attack foreign materials

Neutrophils

Phagocytizes bacteria

Collagen protein fibers

• Unbranched and thicker

• Resistant to stretching

Elastic protein fibers

• Branched and thinner

• Stretch easily

• Stain = black

Reticular protein fibers

• Mesh-like and thinner

• Physically supports organs

Supporting connective tissue

• Provide structural support of the body

• Ex. Bone and cartilage

Cartilage

• Ground substance is a firm gel

• Cells suspended in the gel are called chondrocytes

• Often surrounded by perichondrium (layer of dense connective tissue proper)

• 3 types: hyaline cartilage, elastic cartilage, and fibrocartilage

What type of cartilage?

• Hyaline cartilage

• Dissolved protein fibers

• Location: articular ends of long bones, larynx, trachea, and nose

What type of cartilage?

• Elastic cartilage

• Contains abundant elastic fibers

• Location: external ear and epiglottis of larynx

What type of cartilage?

• Fibrocartilage

• Collage fibers run parallel

• Location: pads within knee joint, between pubic bones and pelvis, and intervertebral discs

Bone

• Ground substance is a semi-solid substance

• It becomes hardened when crystalline mineral deposits are added

• The main cell type is osteocytes

• Protein fiber is mostly collagen

• Two types: compact and spongy

Fluid connective tissue

• Transport substances around the body

• 2 types: blood and lymph