Chapter 5 Tissues

Tissues Cells 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: Epithelial Connective Muscular Nervous

Epithelial Tissues Widespread 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 Epithelium Designed to distend and return to its normal size Found in the urinary bladder Design provides distensibility (stretching) and keeps urine from diffusing back into the internal cavity

Glandular Epithelium Made 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

Cartilage Provides 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

Bone The most rigid connective tissue Bone cells are called osteocytes Has a good blood supply, enabling rapid recovery after an injury.

Blood Composed 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: Skeletal Smooth Cardiac

Skeletal Muscle Tissue Attached 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 Tissue Lacks 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 Tissue Found 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 Tissue Found in the brain, spinal cord and nerves Neurons or nerve cells conduct nervous impulses Neuroglia (helper cells) support and nourish the neurons