Classification of Tissues Exercise 6 Classification of Tissues

What is a tissue? Groups of cells Similar in structure & function Tissues are further organized into organs ( organ systems)

4 Major Tissue Types Epithelial Connective Muscle Nervous

Epithelial Tissues Cover surfaces Simple or stratified? Simple = one layer of cells attached to the basement membrane Stratified = two or more layers of cells Name this epithelia by whichever “shape” the top layer of cells is (apical layer), not the bottom (basal layer)

Epithelial Tissues Shapes of Epithelial Cells Squamous Cuboidal Scalelike, flattened Cuboidal Cubelike Columnar Column-shaped Simple squamous Stratified squamous Simple cuboidal Stratified cuboidal Simple columnar Stratified columnar

Epithelial Tissues Simple squamous epithelium Fig. 4-3

Epithelial Tissues Simple cuboidal epithelium Fig 4-4

Epithelial Tissues Simple columnar epithelium Fig 4-5

Epithelial Tissues Pseudostratified columnar epithelium Actually simple columnar: nuclei are at different levels so there appears to be more than one layer Fig 4-5

Epithelial Tissues Stratified squamous epithelium Fig. 4-3

Epithelial Tissues Stratified cuboidal epithelium Fig 4-4

Epithelial Tissues Stratified columnar epithelium Fig 4-5

Epithelial Tissues Transitional epithelium Stratified squamous epithelium formed of rounded cells that can slide over one another, allowing the organ to stretch: urinary system only Fig 4-4

CONNECTIVE TISSUES Embryonic connective tissue Loose connective tissue mesenchyme Loose connective tissue Areolar, adipose, reticular Dense connective tissue Dense irregular, dense regular Supportive connective tissue Hyaline, elastic, fibrocartilages; bone Fluid connective tissue Blood, lymph

CONNECTIVE TISSUES Differing proportions of cells and fibers to “matrix” Matrix is noncellular, nonliving material between the connective tissue cells Different proportions have to deal with strength of the tissue

Classification of Connective Tissues Fig. 4-8 Many cell types Syrupy ground substance Distinct cell types Watery matrix Less diverse cell types More fibrous matrix

Embryonic Connective Tissue Mesenchyme Many star-shaped stem cells Gives rise to all other connective tissues Not present in adults Fig. 4-10

Loose Connective Tissue Areolar connective tissue Can contain all cells and fibers of any connective tissue Loosely organized ground substance Cushions & protects body’s organs Lots of matrix Fig. 4-9

Loose Connective Tissue Adipose connective tissue (fat) Insulation for the body’s tissues Food storage Little matrix Fig. 4-11

Loose Connective Tissue Reticular connective tissue Reticular fibers form a soft internal skeleton for support Fig. 4-11

Dense Connective Tissue Dense irregular connective tissue Fibers in many directions Dermis Fig. 4-12

Dense Connective Tissue Dense regular connective tissue Fibers in one direction Tendons, ligaments of body’s joints Fig. 4-12

Supportive Connective Tissue Hyaline Cartilage Support, reinforcement Somewhat flexible Most common cartilage Fig. 4-15

Supportive Connective Tissue Elastic Cartilage Maintains shape, but flexible Many elastic fibers Fig. 4-15

Supportive Connective Tissue Fibrocartilage Strength, shock absorption Dense network of collagen fibers Fig. 4-15

Supportive Connective Tissue Osseous Connective Tissue (Bone) Support, protection Fig. 4-16

Fluid Connective Tissue Blood Red blood cells, white blood cells, platelets Transport gases and other nutrients and waste Watery matrix (plasma or serum) Fig. 4-13

Fluid Connective Tissue Lymph Fluid of the lymphatic system Like plasma without the big proteins Immune defense

MUSCLE TISSUES Skeletal Cardiac Smooth

Skeletal Muscle Tissue Attached to the skeleton Under conscious control Striated tissue Long, cylindrical, multinucleate cells Fig. 4-19

Cardiac Muscle Tissue Only in the heart Striated tissue Under involuntary control Branching, uninucleate cells with intercalated discs Fig. 4-19

Smooth Muscle Tissue Found in the walls of hollow organs (digestive, urinary tracts; blood vessels) 2 layers at right angles for contraction/dilation of the organ cavity Not striated tissue Uninucleate, spindle-shaped cells Fig. 4-19

Muscle type Cells striations Voluntary? Cardiac branched Uninucleate Intercalated discs yes no Skeletal Long fibers multinucleate Smooth Spindle shaped 1 nucleus

NERVOUS TISSUE Brain, spinal cord, nerves 2 basic cell types: Neuroglia cells Protect, support, and insulate the neurons Neurons Receive stimuli and conduct nerve impulses all over the body

Fig. 4-20