Connective Tissue 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.

Connective Tissue continued…. 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

Matrix of Connective Tissue 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.

Fibers in 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

“Ideal” Connective Tissue

Cells of 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.

Cells of Connective Tissue continued… 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

Skin The next few slides will illustrate the process of inflammation. The skin forms a barrier to keep microorganisms out of the body. Blood

Tissue Damaged The inflammation process can begin if the skin or other tissues are damaged. *A pin penetrating into the skin can start an inflammation. *Bacteria may enter the body with the pin.

Histamine Released Injured cells will release histamine. *Histamine will diffuse away from the injured cells.

Capillary More Permeable Plasma Leaks Out Histamine will cause capillaries to become more permeable. *This will allow plasma to leak out of the blood.

Capillary More Permeable Antibodies Leak Out Antibodies will also leave the blood capillary*.

Capillary More Permeable WBCs Leave White blood cells will leave the blood by diapadesis*.

Wall of Fibrin Forms The plasma in the injured area will clot to form a wall of fibrin*.

Pus Forms Pus forms within the fibrin wall. The pus is composed of serum, white blood cells and bacteria. The pus will drain and scar tissue will form. At this point the injury to the body has been controlled and homeostasis will be restored. Without the inflammation process the injury could spread. For example, bacteria could spread throughout the body and cause death.

Cells of Connective Tissue continued… Adipocytes: Found in some connective tissues Contain fat

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

Loose Connective Tissue 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

Loose Connective Tissue 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)

Dense Connective Tissue 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 Connective Tissue 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

Dense Connective Tissue 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

Cartilage 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

Types of cartilage continued… Fibrocartilage Large 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 cartilage Elastic fibers and few chondrocytes suspended in a chondrin matrix Found in the outer ear

Bone Characterized by a matrix composed of inorganic minerals. Minerals are embedded in rings Support and protect Histology of bone will be explained later in the Bone unit

Blood 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

Lymph Liquid connective tissue Located in lymphatic vessels- separate from blood vessels No red blood cells nor platelets Fights infection

Fluid Connective Tissue