Chapter 5Tissues

TissuesCells are arranged in tissues that provide

specific functions for the body

Cells of different tissues are structured differently, which leads to their differences in function.

The Tissues of the body include four major types:EpithelialConnectiveMuscularNervous

Epithelial TissuesWidespread throughout the body – Covers

organs and lines body surfaces

Anchored to a basement membrane

Made up of tightly packed cells containing little intercellular material

Generally lack blood vessels

Are frequently replaced

Function in protection, secretion, absorption, excretion and sensory reception.

There are 9 types of Epithelial Tissues

Structure of Epithelial Tissues

Simple Squamous Epithelium

Made up of a single layer of thin, flattened cells

Functions in the exchange of gases in the lungs

Lines blood and lymph vessels as well as body cavities

Simple Cuboidal Epithelium

Consists of a single layer of cube-shaped cells with centrally located nuclei

Functions in secretion and absorption in the kidneys and in secretion in glands

Simple Columnar Epithelium

Made up of rows of elongated cells whose nuclei are all located near the basement membrane

Lines the uterus, stomach and intestines where it protects underlying tissues, secretes digestive fluids and absorbs nutrients

In the intestine, these cells possess microvilli that increase the surface area available for absorption.

Pseudostratified Columnar Epithelium

Appeared layered due to the varying positions of their nuclei within the rows of cells, but are not truly layered.

Cilia may be present

Cilia on these cells aid in moving eggs through oviducts to the uterus in the female reproductive system

Stratified Squamous Epithelium

Made up of layers of flattened cells that are designed to protect underlying layers

Makes up the outer layer of skin

Lines the mouth, throat, vagina and anal canal

Stratified Cuboidal Epithelium

Consists of two to three layers of cuboidal cells lining a lumen (opening) of the mammary glands, sweat glands and pancreas.

Several layers of cells provide greater protection than a single layer.

Stratified Columnar Epithelium

Consists of several layers of cells

Found in part of the male urethra and parts of the pharynx

Transitional EpitheliumDesigned to distend and return to its

normal size

Found in the urinary bladderDesign provides distensibility (stretching)

and keeps urine from diffusing back into the internal cavity

Glandular EpitheliumMade up of cells designed to produce and

secrete substances into ducts or into body fluids

Exocrine glands – glands that secrete products into ducts

Endocrine glands – glands that secrete products directly into body fluids and blood.

Glandular Epithelium

Connective Tissues

Bind, support, protect, serve as frameworks, fill spaces, store fat, produce blood cells, protect against infection and repair tissue damage

Unlike epithelial tissues, connective tissues have abundant intercellular material and have good blood supplies (except in cartilage)

There are 6 types of connective tissues

Loose Connective Tissue

Forms delicate, thin membranes throughout the body that bind body parts together.

Binds the skin to underlying organs and fills spaces within muscle.

Adipose Tissue

Designed to store fat

Found beneath the skin, around joints, padding the kidneys and other internal organs, and in certain abdominal membranes.

Dense Connective Tissue

Consists of densely packed fibers and is very strong, but lacks a good blood supply.

Is found as part of tendons and ligaments

CartilageProvides a supportive framework for various

structures.

Hyaline Cartilage – is white with abundant fine collagen fibers Is found at the end of bones and supports respiratory

passages

Elastic Cartilage Provides a framework for the external ears and parts of

the larynx

Fibrocartilage Tough tissue that provides a shock-absorbing function in

intervertebral disks and in the knees and pelvic girdle

Cartilage

BoneThe most rigid

connective tissue

Bone cells are called osteocytes

Has a good blood supply, enabling rapid recovery after an injury.

BloodComposed of red

and white cells suspended in plasma

Formed in the red bone marrow

Functions to transport substances throughout the body.

Muscular Tissue

Muscle cells or fibers can contract

Muscular tissue consists of three main types:SkeletalSmoothCardiac

Skeletal Muscle TissueAttached to bone

Voluntary – can be controlled by conscious effort

Cells (muscle fibers) are long and cylindrical, striated (striped) and have many nuclei

Contract from nervous impulse and then relaxes

Smooth Muscle TissueLacks striations, only

has one nucleus, and consists of spindle shaped cells

Involuntary – is not controlled consciously

Found in the walls of internal organs and in the digestive tract, blood vessels and urinary bladder

Cardiac Muscle TissueFound only in the

heart

Consists of branching fibers that are connected to each other

Has a single nucleus in each cell, but appears stretched

Nervous TissueFound in the

brain, spinal cord and nerves

Neurons or nerve cells conduct nervous impulses

Neuroglia (helper cells) support and nourish the neurons