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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