What is a tissue?

?A collection of cells with similar structure that�s function is to carry out specialized activities.

4 basic categories of tissues in human body



? lines body cavities and ducts? No blood supply (avascular)? Anchored in place by a basement membrane? Functions are to protect, absorp, diffuse, secrete, and lubricate.Forms secretory portions of most glandsIn the outer surface of skin, lining of GI tract, respiratory tract, and lining of blood vessels

simple Cuboidal

one layer of deep, square (box- or cube- like) cellsfound: surface of ovaries, ducts of some glands

Simple squamous

1 layer of flat, scale-like cells; have central nuclei;adapted for diffusion and filtrationfound: inside lungs, blood vessels, capillaries; lens of eye; eardrum

Simple columnar

one layer of long, tall cells (like a fence); nuclei of neighboring cells are usually found at same height along bottom of cells; May have extensions of the membrane called microvilli (brush border);May have goblet cells which produce mucus;May have cilia on outside of membrane to propel particles (and mucus) along surface of the cells found: lining the digestive tract � with microvilli from stomach to anus; Ciliated columnar epithelium is found in portions of the upper respiratory tract, and the uterus




Notice how the bottom layer(Red Line), looks cuboidal in naturebut the because the top layer is columnar,and it is the top layer which determines the classification, this is called stratified columnar.Green line - Top layerRed Line - Bottom layer

Pseudostratified columnar

cells appear to be stratified but are not;nuclei are at different levels and some cells do not reach the surface. found: Eustachian tubes (internal auditory tubes) and in the upper respiratory tract; nonciliated found in male urethra

Connective Tissue

? supports, protects and binds other tissues together? has few cells that are widely separated by large amounts of material between the cells? e.g. adipose tissue, cartilage, bone, blood

Connective Tissue Cell types

1. Fibroblast2. Macrophage3. Mast cells 4. Blood cells

1. Fibroblast

? large star shaped cell whose function is to produce intercellular matrix; this matrix is largely the protein collagen

2. Macrophage

? a phagocyte attached to fibroblasts

3. Mast cells

? found near blood vessels for the inflammatory response

4. Blood cells

? RBC's and WBC's and platelets

Areolar �

found beneath the skin; has white collagen and yellow elastic fibers; flexible

Adipose �

this type of connective tissue has very little intercellular matrix. Each cell contains a large drop of fat that pushes the cytoplasm (and nucleus) into a thin band around the outer edge of the cell. This fat is stored as a food source, as insulation, and as a cushion

Dense - connective tissue

Tendons - connect muscle to boneLigaments - connect bones to bone connective tissue which is closely packed with high amounts of collagen and elastic fibers in matrix; tough; periosteum, fasciaCartilageHyaline cartilage- �gristle� - gives shape (to nose, larynx, trachea, bronchi), connects (ribs) and is found on ends on bones in joints; (most cartilage is this type)

Fibrous cartilage

contains fibers; Found in vertebral discs

Elastic cartilage

has elastic fibers; found in ear (pinna), epiglottis


hemopoietic tissue


? consists of elongated cells that are capable of contracting? produces the movement of body parts? e.g. skeletal muscle, cardiac, smooth muscle

Muscle Tissue

Striated - makes up skeletal muscles; (voluntary muscles)cells have striations or stripes and many nuclei;

Smooth muscles

makes up the walls of hollow organs, as in respiratory, digestive reproductive tracts and blood vessels; involuntary muscles

Cardiac muscle

in heart only; resembles striated muscle tissue but also has branches; Involuntary muscle


? consists of neurons and associated support cells? they�re capable of conducting electrical impulses between body sites? e.g. brain, spinal cord, and nerves

Nervous Tissue

makes up the brain, spinal cord and nerves;initiates and sends nerve impulses; directs and coordinates all body�s activitiesNeuron - principal cell of nervous system