Cells and Tissues Cells - building blocks of all life

Tissues - groups of cells w/ similar structure and function

Body Tissues – groups of cells with similar structure and function

Four primary types

Epithelial tissue (epithelium)

Connective tissue

Muscle tissue

Nervous tissue

Epithelial Tissues

Locations

Body coverings

Body linings

Glandular tissue

Functions

Protection

Absorption

Filtration

Secretion

Epithelium Characteristics

Often form sheets (like skin)

apical surface = free surface (top side)

lower surface bound to basement membrane

Avascular (no blood supply), but regenerate easily

Apical Surfaces

Classification of Epithelia

Simple—one layer

Stratified—more than one layer

Figure 3.17a

Classification of Epithelia

Shape of cells

Squamous – flattened

Cuboidal - cube-shaped

Columnar - column-like

Figure 3.17b

Simple Squamous Epithelia – Line body cavities, lungs, capillaries

Figure 3.18a

Simple Cuboidal Epithelia – many glands, kidney tubes, cover ovaries

Simple Columnar Epithelia – usually includes goblet cells (mucus makers), lines stomach to anus

Stratified Squamous Epithelia – skin, mouth, esophagus: protect against friction

Stratified cuboidal and columnar epithelia

Rare

Found mainly in ducts of large glands

Pseudostratified Columnar Epithelia – seem stratified but not, line trachea

Transitional Epithelia – stretchy, urinary bladder

Glandular Epithelium

Endocrine gland – secrete hormones directly to blood

Exocrine gland – secrete into ducts, sweat glands for ex.

Connective Tissue

Found everywhere in abundance

Functions

Binds tissues together

Support

Protection

Connective Tissue Characteristics

Blood supply varies (a little to a lot)

Extracellular matrix: non-living material surrounding cells (2 components)

Ground substance: water, proteins, sugars

Fibers: protein fibers secreted by cells

Connective Tissue: BONE – protection and support

Hard matrix of calcium salts

Large numbers of collagen fiber

Connective Tissues: Hyaline Cartilage – protects joints, supports trachea

Most common type of cartilage

Composed of

Abundant collagen fibers

Rubbery matrix

Connective Tissue Types

Elastic cartilage – elastic ear support

Fibrocartilage – compressible discs between vertebrae

Connective tissues: dense connective tissue

Tendons - skeletal muscle to bone

Ligaments— attach bone to bone at joints

Dermis— lower layers of the skin

Connective Tissue Types: Loose Connective Tissues are soft and pliable

Areolar tissue

Most widely distributed connective tissue

Functions as a packing tissue

Can soak up excess fluid (causes edema)

Adipose tissue

Areolar tissue with fat cells

Insulates, protects, stores fuel

Connective Tissue Types: reticular tissue (also a loose connective tissue)

Delicate network of interwoven fibers

Creates space in lymph nodes, spleen, bone marrow

Connective Tissue Types: Blood

Blood cells surrounded by fluid matrix (blood plasma)

Transports nutrients/waste/hormones

Body MembranesComposed of epithelial and connective tissues.

Cover body surfaces

Line body cavities

Protect organs

4 types-

Mucous membranes – ‘wet’ membranes that open to exterior; Respiratory, urinary, digestive, etc.

Serous membranes – line body cavities, completely separate from exterior

4 types-

Cutaneous membranes – the skin, exposed directly to air

Synovial membranes -- lines capsules around joints, secretes lubricating fluid

Muscle Tissue – 3 types for movement

Skeletal muscle – voluntary control, multi-nucleate fibers, striated

Cardiac muscle – heart, intercalated discs, single branched cells

Smooth muscle – involuntary control (hollow organs & blood vessels)

Nervous Tissue – neurons and support cells

Sends impulses around the body

Irritability – detect environmental changes

Conductivity – send electrical signals

Tissue Repair (Wound Healing)

1. Blood clots seal off damaged area.

2. New capillaries grow into damaged area to deliver nutrients.

3. Epithelial and vascular connective tissues tend to regenerate; muscle and nerve tissue replaced with scar tissue.