4 Types of Tissues Epithelial
Covers body surfaces and lines hollow organs, body cavities, duct, and forms glands
Connective Protects, supports, and binds organs. Stores energy as fat, provides immunity
Muscular Generates the physical force needed to make body
structures move and generate body heat Nervous
Detect changes in body and responds by generating nerve impulses
Development of Tissues Tissues of the body develop
from three primary germ layers: Ectoderm, Endoderm,
and Mesoderm Epithelial tissues develop
from all three germ layers All connective tissue and
most muscle tissues drive from mesoderm
Nervous tissue develops from ectoderm
Internal organs develop from endoderm
Tight Junctions
Web-like strands of transmembrane proteins Fuse cells together Seal off passageways
between adjacent cells Common in epithelial
tissues of the stomach, intestines, and urinary bladder
Help to retard the passage of substances between cells and leaking into the blood or surrounding tissues
Desmosomes
Contain plaque and cadherins that extends into the intercellular space to attach adjacent cells together Desmosome plaque
attaches to intermediate filaments that contain protein keratin
Prevent epidermal cells from separating under tension and cardiac muscles cells from pulling apart during contraction
Gap Junctions
Connect neighboring cells via tiny fluid-filled tunnels called connexons Contain membrane proteins
called connexins Plasma membranes of gap
junctions are separated by a very narrow intercellular gap (space) Communication of cells
within a tissue Ions, nutrients, waste,
chemical and electrical signals travel through the connexons from one cell to another
Epithelial Tissues Epithelial tissue consists of
cells arranged in continuous sheets, in either single or multiple layers Closely packed and held tightly
together Covering and lining of the body Free surface
3 major functions: Selective barrier that regulates
the movement of materials in and out of the body
Secretory surfaces that release products onto the free surface
Protective surfaces against the environment
Connective Tissue Most abundant and widely
distributed tissues in the body
Numerous functions Binds tissues together
(tendons/ligaments) Supports and strengthen
tissue (bone) Protects and insulates internal
organs (fat) Compartmentalize and
transport (blood) Energy reserves and immune
responses
Connective Tissue Extracellular Matrix Ground substance
Between cells and fibers Fluid, semifluid, gelatinous, or calcified
Functions to support and bind cells, store water, and allow exchange between blood and cells
Complex combination of proteins and polysaccharides
Fibers Collagen fibers Elastic fibers Reticular fibers
Muscular Tissue Consists of elongated
cells called muscle fibers or myocytes Cells use ATP to
generate force Functions in movement,
generating heat, digestion
Classified into 3 types: skeletal, cardiac, and smooth muscular tissue
Skeletal Muscle Tissue
Attached to bones of the skeleton Have striations Voluntary movement or contractions by conscious control Vary in length (up to 40 cm) and are roughly cylindrical in
shape
Muscular Tissue
Cardiac muscle tissue Have striations Involuntary movement or contraction is not consciously
controlled Intercalated disc unique to cardiac muscle tissue
Smooth Muscle Tissue Walls of hollow internal structures
Blood vessels, airways of lungs, stomach, and intestines Nonstriated Usually involuntary control
Nervous Tissue Consists of two principle types of cells
Neurons or nerve cells Neuroglia
Cellular Movement
Microtubules cilia & flagella Microfilamentsamoeboid
movement & muscle cells
Vertebrate skeletal muscle
The action of muscle is to always contract
Muscles are attached in antagonistic pairs
The basic functional unit of muscle
)Myofilaments
Skeletal muscles: striated & multinucleate
I=thinH=thickA=thick + thin A A
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