The four main types of body tissues are: Epithelium – Sheets of tissue that line and cover, provide protection specialized for absorption/secretion Connective – Provide support and framework. Muscle – Provide movement Nervous – Provide communication

CONNECTIVE TISSUES These tissues are the most abundant tissues in the body and they show the most variation in their functions. Derived from MESODERM May act to build structures, connect one tissue to another, anchor structures, support, defense, transportation and protection.

With That Much Diversity – What Do They Have In Common? Connective tissues differ from epithelial tissues in both their arrangement and in the amount and type of intercellular material -MATRIX (material found between cells). Same Embryonic origin.

Connective Tissue Composition 1. Tend to have few cells in comparison to the amount of space the tissue occupies. 2. Extracellular matrix (non-living material secreted by cells) is found between the living cells. The matrix and fibers found between the cells is ultimately what determines the qualitative characteristics of that connective tissue.

Common Types of Connective Tissues Areolar – Adhesive connective tissue. Adipose – Fatty tissue consisting of adipocytes. Fibrous Connective Tissue – Forms tendons to attach muscle to bones. Bone – Living cells that secrete calcium deposits. Cartilage – Chondrocytes lay out gristle-like gel matrix. Blood – Erythrocytes (red), leukocytes (white) and thrombocytes (platelets) in a fluid matrix (plasma). Hemopoietic – Found in red bone marrow cavities, produces new blood cells.

AREOLAR STRUCTURE and FUNCTION: This connective tissue forms the “GLUE” for other tissues. Has gel-like matrix with several different types of fibers in gel for reinforcement. Wraps and cushions organs, holds tissues together.

ADIPOSE STRUCTURE and FUNCTION: Small amounts of gel-like matrix in between closely packed adipocytes (fat cells) Provides reserve food fuel, insulates body against heat loss, and provides padding.

FIBROUS CONNECTIVE TISSUE STRUCTURE and FUNCTION: Cells synthesize and secrete collagen protein fibers that run parallel to each other. Attach muscles to bones (TENDONS), attach bones to bones (LIGAMENTS). Strong and flexible but no ability to stretch. Collagen :stronger than wire

BONE STRUCTURE and FUNCTION: Osteocytes (bone cells) secrete calcified matrix, which has many channels for vascularization. Bones support and protect, provides levers for muscle contraction to work on, stores calcium and other minerals, stores marrow for blood cell formation.

CARTILAGE STRUCTURE and FUNCTION: Chondrocytes (cartilage cells) produce and secrete a gristle-like matrix surrounding themselves. Cartilage acts to support and reinforce joints, acts to cover and cushion bones at the joints.

BLOOD STRUCTURE and FUNCTION: Red and white blood cells along with cell fragments (platelets) in a fluid matrix called plasma. Erythrocytes and plasma transport respiratory gases (O2 and CO2), nutrients, wastes and other substances (hormones) Leukocytes = Fight infection Thrombocytes = Clotting

HEMOPOIETIC STRUCTURE and FUNCTION: Blood stem cells found in spleen, tonsils, red bone marrow, lymph nodes. Stem cells found closely packed together in a liquid matrix Blood cell formation