Classification of Tissues Chapter 6 Classification of Tissues

Tissues and tissue types Tissues are: Group of cells similar in structure an function Tissues are organized into organs Histology = study of tissues The four tissue types are: Epithelial Connective Muscular Nervous

Functions of epithelium Physical protection Secretion Sensory perception Absorption Filtration Excretion

Epithelial tissue Includes glands and epithelium Glands are secretory Avascular Polarity Regeneration Cellularity Supported by connective tissue Attached to a basement membrane

Basement Membrane Amorphous substance. Divided in 2 layers: Lamina lucida (basal) Secreted by the epithelium Lamina densa (reticular) Secreted by the connective tissue

Specializations of epithelium Ciliated Microvilli Stereocilia Flagella

Classification of epithelia Number of cell layers Simple Stratified Shape of apical surface cells Squamous Cuboidal Columnar

STRATIFIED SQUAMOUS WITH KERATIN

Cuboidal Epithelia

SIMPLE CUBOIDAL EPT.

Cuboidal Epithelia Figure 4.4b

Transitional Epithelium Figure 4.4c

TRANSITIONAL EPT.

Columnar Epithelia Figure 4.5a

SIMPLE COLUMNAR EPT.

Columnar Epithelia Figure 4.5b

Columnar Epithelia Figure 4.5c

Glandular epithelia Epithelium that secrete substances Exocrine glands Secrete through ducts onto the surface of the gland Endocrine glands Release hormones into surrounding fluid. Ductless glands.

GOBLET CELLS

Part 2

Connective Tissues

Connective tissue functions and classification: Protects Supports Bind tissues together Classification: Embryonic Mesenchime Loose connective tissue, mucous Adult

A Classification of Adult Connective Tissues

Connective tissues characteristics No free surface Vascular Scanty in tendons Except cartilage Supports the body Maintain body form

Components of the connective tissue 1)Extracellular matrix Ground substance Amorphous Binds cells to fibers Colorless Homogeneous Liquid, semisolid, gel-like, or hard

Matrix Fibers Collagen (white) Most abundant Brings flexibility and strength to the tissue Thicker one Elastic (yellow) Brings elasticity to the tissues Can stretch and recoil

Fibers Reticular Thinnest one Found in smooth muscle and framework of the organs Brings flexibility to organs that need changes in volume

RETICULAR TISSUE

DENSE IRREGULAR WITH COLLAGEN, ELASTIC AND RETICULAR FIBERS

Components of the connective tissue 2) Cells Fibroblast most abundant Synthesis of fibers and ground substance Macrophage Phagocytic capacity

Components of the connective tissue Adipocytes Closely packed Signet ring cell Nucleus eccentric and flat Mesenchymal cells Mast cells Releases histamin Responsible for allergic reactions Lymphocytes, etc

The Cells and Fibers of Connective Tissue Proper

Connective tissue proper Classified as loose or dense Loose Areolar tissue Adipose tissue Reticular tissue Rich blood supply

Connective tissue proper Dense Dense regular Dense irregular Elastic Poor blood supply

Connective Tissue in Embryos

AREOLAR TISSUE

ADIPOSE AND DENSE IRREGULAR TISSUES BLOOD VESSELS SHOWING SIMPLE SQUAMOUS EPT.

RETICULAR CONNECTIVE TISSUE

Dense Connective Tissues Figure 4.12a

Dense Connective Tissues Figure 4.12b

Dense Connective Tissues Figure 4.12c

DENSE ELASTIC

DENSE REGULAR TISSUE

DENSE IRREGULAR WITH COLLAGEN FIBERS

Bone, or osseous tissue Has osteocytes and osteoblasts Lacuna Little ground substance Dense mineralized matrix Richly Vascularized

Bone

Part 3

Supporting connective tissues: Cartilage Cells called chondrocytes or chondroblasts Cells found in lacunae Firm matrix Avascular Three types: hyaline, elastic, fibrocartilage

Types of Cartilage

HYALINE CARTILAGE

Types of Cartilage

ELASTIC CARTILAGE

Types of Cartilage

FIBROCARTILAGE

Fluid connective tissues Blood Red blood cells, white blood cells and platelets Plasma is the fluid matrix

Formed Elements of the Blood

Muscle tissue Specialized for contraction Three types Skeletal Cardiac Smooth

Skeletal muscle Cells are multinucleate, long, cylindrical Presence of striation Voluntary muscle

Muscle Tissue - Skeletal

SQUELETAL MUSCLE

Cardiac muscle Cells: Long, 1 or 2 nucleus Branching cells Intercalated discs Presence of striation Involuntary muscle

Muscle Tissue - Cardiac

CARDIAC MUSCLE

Smooth muscle tissue Cells Fusiform One central nucleus Non-striated Involuntary muscle Forms the wall of hollow organs

Muscle Tissue - Smooth

SMOOTH MUSCLE Use spaghetti for longitudinal x transverse cut.

Nervous Tissue

Neural tissue cells Neurons Transmits impulses No intercellular matrix Neuroglia Support, protects and insulates the nervous tissue Greater number

Neural tissue location Brain Spinal cord Nerves

NEURONS AND NEUROGLIAS