The most abundant and widely distributed type of tissue in the whole body.

General characteristics: With the exception of 3 types, connective

tissues have a great blood supply. Reproduce quickly Classified as being “connective” because

at least 50% of the tissue is non-living.

Function: Designed to bind tissues together Helps protect the body Store energy in the form of fat Transport materials throughout the body

(blood, lymph) 2 main components of connective tissue:

Matrix Cells

A base material that contains protein fibers and is found between the cells of connective tissue.

Functions to support the cells of the connective tissue

Non-living The structure of the matrix determines the

characteristics of the connective tissue Fibers are proteins found in the matrix that

strengthen and support connective tissue.

The properties of a connective tissue can change if the types/amounts of fibers in the matrix change.

Types of fibers: Collagen- Very strong and slightly flexible

and add strength to connective tissue Elastic- Strong and very flexible fibers Reticular- Strong and highly branching fibers

that help form the framework of a connective tissue

Not all of the possible types are found in all connective tissues Fibroblasts:

▪ Make the fibers found in the matrix▪ Found in most connective tissues

Phagocytes:▪ Macrophages and neutrophils- Phagocytic cells that “eat and eliminate” foreign materials.

Plasma cells: Found in most connective tissues Produce antibodies

▪ Antibodies- Molecules that help protect us from foreign particles

Mast cells: Found in all connective tissues Release histamine

▪ Histamine- Causes swelling because it signals for blood vessels to become more “leaky” and signals for blood to rush to an area

Blood

Plasma Leaks Out

Antibodies Leak Out

WBCs Leave

Adipocytes: Found in some connective tissues Contain fat

There are 6 types of mature connective tissue. They include: loose connective tissue, dense connective tissue, cartilage, bone tissue, blood tissue and lymph.

Loosely arranged fibers in the matrix. Areolar- Loose arrangements of collagen, elastic and

reticular fibers present in the matrix▪ Location: In and around every body structure so is

often called the “packing material” of the body.▪ Function: Binds structures together, provides

strength (collagen), and provides flexibility (elastic) Adipose- Lipids (fats) present in the matrix

▪ Location: Below the skin and surrounding organs▪ Function: Stores fat, insulates against heat loss, and

protects organs

Reticular- Loose arrangements of reticular fibers and reticulocytes in the matrix

▪ Reticulocytes are a type of fibroblast that specifically secrete lots of reticular fibers.

▪ Function: Form the framework for larger organs (like the framework of a house)

Large amounts of thick, dense fibers and fewer cells than loose connective tissue

Dense regular- Parallel bundles of collagen fibers present in the matrix▪ Connects muscle to bone (tendon) or bone to bone

(ligament)▪ Can resist lots of force along the length of the fibers▪ A force against the fibers can tear them (torque)▪ Poor blood supply so it takes a long time to heal

Dense irregular- Random arrangements of collagen fibers present in the matrix.▪ Good blood supply▪ Makes up the dermis (middle layer) of the skin

▪ Resists pulling forces in multiple directions

Elastic: Freely branching elastic fibers present in the matrix.▪ Good blood supply▪ Makes up the wall of an artery▪ Allows a hollow structure to expand and recoil freely▪ This keeps blood moving along in arteries

Consists of a dense network of collagen and elastic fibers in a semi-solid matrix

Poor blood supply▪ Chondrin- Gel-like protein found making up the matrix

of cartilage tissue▪ Types of cartilage

▪Hyaline Cartilage cells (chondrocytes) suspended in a chondrin matrix.

Acts as a shock absorber Covers the ends of bones at a joint

▪FibrocartilageLarge bundles of collagen fibers and few chondrocytes suspended in a chondrin matrix

Found in the knee meniscus and the disks between vertebrae

Acts as a shock absorber

▪Elastic cartilageElastic fibers and few chondrocytes suspended in a chondrin matrix

Found in the outer ear

Characterized by a matrix composed of inorganic minerals.

Minerals are embedded in ringsSupport and protectHistology of bone will be explained

later in the Bone unit

Liquid connective tissue Transports materials throughout the body 2 basic components:

Plasma- ▪ 55% of total blood▪ mostly water▪ supports the formed elements

Formed elements (cells)-▪ Erythrocytes- red blood cells- transport oxygen- outnumber white

cells 700:1▪ Leukocytes- white blood cells- fight infection▪ Thrombocytes- platelets- cell fragments- help form blood clots

Liquid connective tissueLocated in lymphatic vessels-

separate from blood vesselsNo red blood cells nor plateletsFights infection

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