passageway between two adjacent cells. Cells are connected by hollow cylinders of protein. Function in intercellular communication.
Basal Lamina noncellular supporting sheet between the ET and the Connective Tissue of proteins secreted by ET cells
Functions: Acts as a selective filter determining which molecules form capillaries enter the epithelium. Also acts as scaffolding along which regenerating ET cells can migrate. CT and Basal Lamina form the basement membrane
Apical Surface Features
Microvilli- fingerlike extensions of plasma membrane.
Abundant in ET of small intestine and kidney.
Purpose: Maximize surface area across which small molecules enter or leave. Acts as stiff knobs that resist abrasion.
Connective Tissue Functions and Orgin
Function: Structural framework; Fluid and Solute transport; Physical Protection; Tissue Interconnection; Fat Storage; Microorganism defense.
Embryonic Orgin- mesenchyme
Connective Tissue Components
Specialized cells and extracellular matrix. Cells are resident or migrating.
Fiborblasts (makes the extracellular matrix and collagen)
Macrophages (White blood cells that engulf)
Fat cells (adipose)
Mast Cells (histamine)
Other White Cells
Composed of ground substance and fibers, produced by fiborblasts. There are 3 types of fibers that provide support.
Collagen: resist stretching (high tensile strength)
Areolar Connective Tissue
Gel like matrix with all 3 fibers. Cells are fibroblasts, macrophages, mast cells and white blood cells.
Function: Wraps and cushions organs, holds and conveys tissue fluid, important role in inflammation. Main defense site against infection, gathering of macrophages plasma cells mast cells and white blood cells.
Areolar Connective Tissue Location
Widely distributed under epithelia. Borders all other tissues in the body. Packages organs. Surrounds small nerves and blood Vessels
Fat. Closely packed adipocytes have nuclei pushed to one side by fat droplet.
Function: Provides reserve food fuel, insulates against heat loss, supports and protects organs.
Location: under skin, around kidneys, behind eyeballs, within abdomen and breast
Reticular Connective Tissue
Network of reticular fibers in loose ground substance.
Function: Form a soft internal skeleton (stroma) that supports other cell types
Location: Lymphoid organs, lymph nodes, bone marrow, and spleen
Connective Tissue Proper
Dense Connective Tissue:
Dense irregular connective tissue
Dense regular connective tissue
Elastic Connective Tissue
Dense Irregular Connective Tissue
Primarily irregularly arranged collagen fibers some elastic fibers and fibroblasts.
Function: Withstands tension, provides structural strength
Location: Dermis of skin, submucosa of digestive tract, fibrous capsules of joints and organs
Dense Regular Connective Tissue
Consist primarily of parallel collagen fibers fibroblasts and some elastic fibers that are poorly vascularized.
Function: Attaches muscle to bone (tendons) and bone to bone (ligaments), withstands great stress in one direction
Location: Tendons and ligaments, aponeuroses, fascia around muscles
Elastic Connective Tissue
Elastic fibers dominate
Function: Allows recoil after stretching
Location: Within walls of arteries, certain ligaments, and surrounding bronchial tubes
Firm Flexible Tissue contains no blood vessels or nerves. Contains up to 80% water. Made up of Chondrocyte cells.
3 Different Types:
Imperceptible collagen fibers (glassy) chodroblasts produce matrix chondrocytes lie in lacuna (part of bone).
Function: Supports and reinforces resilient cushion resists repetitive stress.
Location- fetal skeleton, end of long bones, costal cartilage of ribs, cartilages of nose, trachea, and larynx.
Similar to hyaline cartilage more elastic fibers in matrix
Function: Maintains shape of structure allows great flexibility
Location: External Ear and Epiglottis ( the flap in your throat that directs air and food)
Matrix similar but less firm than hyaline cartilage, thick collagen fibers predominate has blue tint when stained.
Function: Tensile strength and ability to absorb compressive shock
Location: Intevertebral disc, pubic symphysis, discs of knee joint.
Calcified matrix containing many collagen fibers, Osteoblasts secrete collagen fibers and matrix osteocytes are mature bone cells in lacunae, well vascularized
Bone Tissue Function and Location
Function: Supports and protects organs, provides levers and attachment site for muscles, stores calcium and other minerals stores fat marrow is site for blood cell formation
Consists of cells surrounded by nonliving matrix (atypical connective tissue) red and white blood cells surrounded by fluid matrix (plasma)
Function: Transport of respiratory gases nutrients and waste
Location: Within blood cells.