Histology

4 Types of Tissues Human Body Tissues Connective MuscleNeural

What are Epithelial Tissues? Structure Cover internal and external surfaces Close together Avascular Easily regenerated Life span: 1-2 days Basement membrane: attaches epithelia to underlying connective tissue Made of protein fibers Functions Protection Permeability Secretion Exocrine glands

4 Types of Tissues Human Body Tissues Connective MuscleNeural

What are Connective Tissues? Structure Highly vascular 3 Components: 1.Cells 2.Protein Fibers 3.Ground Substance Functions (lots of variation!) Support & Protect – framework Transport materials – fluid with dissolved materials Energy reserve – fat in adipose tissue Defense – responds to pathogens by releasing antibodies Protection of organs

3 Types of Connective Tissues 1.Connective Tissue Proper Syrupy ground substance Ex: Loose (areolar, adipose) & Dense (ligaments, tendons) 2.Fluid Connective Tissue Cells suspended in watery ground substance with dissolved proteins Ex: Blood & Lymph 3.Supporting Connective Tissue Dense ground substance Closely packed fibers Ex: Cartilage (hyaline, elastic, fibrocartilage) & Bone

1. Connective Tissue Proper – Loose Connective Tissue Areolar Tissue Contains all cells and fibers of connective tissue proper Separates skin from muscles Provides padding Allows movement Extensive blood supply Adipose Tissue Adipose (fat) cells Behind eyes, kidneys, heart, abdomen, buttocks, & breasts

1. Connective Tissue Proper – Dense Connective Tissue Mostly collagen Regular – collagen fibers are parallel Tendons – connect skeletal muscle to bone Ligaments – connect bone to bone, contain elastin

2. Fluid Connective Tissue Blood Plasma – watery matrix with dissolved proteins Red Blood Cells White Blood Cells Platelets Lymph Interstitial fluid (water & solutes) enters lymphatic vessels

3. Supporting Connective Tissue - Cartilage Cartilage – gel with embedded fibers Chondrocyte – mature cartilage cells Difficult to repair – no blood vessels 3 Types: 1.Hyaline – closely packed fibers, tough but flexible Connects ribs to sternum, supports trachea of respiratory tract, covers bone surfaces in joints 2.Elastic – elastic fibers, very flexible External flap of outer ear, epiglottis, auditory tube 3.Fibrocartilage – little ground substance, collagen fibers, durable & tough Between vertebrae, between pubic bones, around or within some joints

Hyaline Cartilage Elastic Cartilage Fibrocartilage

3. Supporting Connective Tissue - Bone Osseous Tissue – bone Matrix – hard calcium & flexible collagen Little ground substance Osteocytes found in lacunae Lacunae surrounded by blood vessels Canaliculi extend from central canal

4 Types of Tissues Human Body Tissues Connective Neural

What are Muscle Tissues? Specialized for contraction 3 Types: 1.Skeletal Muscle – striated, voluntary muscle Large multinucleated cells (long & slender) Striations (series of bands) 2.Cardiac Muscle – striated, involuntary muscle Smaller striated cells, one nucleus Interconnected by intercalated discs only found in the heart 3.Smooth Muscle – nonstriated, involuntary muscle Small, slender cells with one nucleus walls of blood vessels, hollow tube- like organs

4 Types of Tissues Human Body Tissues Connective

What are Neural Tissues? Specialized for conducting electrical impulses Neurons – communicate through electrical events Long cell with 3 main parts 1.Cell body with nucleus 2.Dendrites – branching projections that receive info 3.Axon – long projections (with synaptic terminals) that relay signals to other cells Limited ability to repair