Connective, Muscle, Nervous, and Tissue Repair: Key Concepts

Where is dense connective tissue found?

Tendons, ligaments, and the dermis of the skin.

Loose connective tissue

Connective tissue with many cells and fewer fibers.

Three types of loose connective tissue

Areolar, adipose, and reticular.

Areolar connective tissue

Most widely distributed connective tissue that cushions organs.

Function of areolar tissue

Binds tissues, cushions organs, and stores water and salts.

Edema

Swelling caused by excess fluid in areolar tissue.

Adipose tissue

Fat tissue specialized for energy storage.

Functions of adipose tissue

Energy storage, insulation, and protection.

Where is adipose tissue commonly found?

Under the skin and around organs such as the kidneys.

Reticular connective tissue

Forms the supporting framework (stroma) of soft organs.

Where is reticular connective tissue found?

Lymph nodes, spleen, and bone marrow.

Blood

A connective tissue with cells suspended in plasma.

Why is blood considered connective tissue?

It has living cells surrounded by a fluid extracellular matrix.

Blood plasma

The fluid matrix of blood.

Main functions of blood

Transports oxygen, nutrients, wastes, hormones, and immune cells.

Three types of muscle tissue

Skeletal, smooth, and cardiac.

Skeletal muscle

Voluntary, striated muscle attached to bones.

Function of skeletal muscle

Moves the skeleton.

Appearance of skeletal muscle cells

Long, cylindrical, multinucleated, and striated.

Smooth muscle

Involuntary, nonstriated muscle found in hollow organs.

Locations of smooth muscle

Stomach, intestines, bladder, uterus, and blood vessels.

Appearance of smooth muscle cells

Spindle-shaped with a single nucleus.

Cardiac muscle

Muscle found only in the heart.

Characteristics of cardiac muscle

Branched, striated, involuntary, with intercalated discs.

Intercalated discs

Specialized junctions connecting cardiac muscle cells.

Function of gap junctions in cardiac muscle

Allow electrical signals to spread rapidly between cells.

Functional syncytium

Heart muscle cells contracting together as one unit.

Nervous tissue

Tissue specialized for communication using electrical impulses.

Neuron

The functional cell of nervous tissue.

Neuroglia

Supporting cells that protect, nourish, and insulate neurons.

Two major functions of nervous tissue

Irritability and conductivity.

Regeneration

Replacement of damaged tissue with the same type of cells.

Fibrosis

Repair by scar tissue formation.

Which tissues regenerate well?

Epithelial tissue, bone, mucous membranes, and fibrous connective tissue.

Which tissues regenerate poorly?

Cardiac muscle, skeletal muscle, and nervous tissue.

First stage of tissue repair

Inflammation.

Purpose of inflammation

Stops bleeding, prevents infection, and begins healing.

Granulation (proliferative) phase

Formation of new capillaries, fibroblasts, and collagen.

Fibroblasts

Cells that produce collagen fibers during healing.

Remodeling phase

Final stage where scar tissue matures and epithelium regenerates.

Scab

Dried blood clot that protects the wound during healing.

Phagocytes

Cells that remove bacteria and dead tissue during healing.

Collagen during wound healing

Provides strength to repaired tissue.

Factors determining tissue repair

Type of tissue damaged and severity of injury.