BODY TISSUES, BODY MEMBRANE, AND
TISSUE REGENERATION
DR LSK
.
1
Objectives
At the end of the lecture, the student should be able to
Discuss the location of principal body tissues
Discuss their structure and function
Tissue Homeostasis
2
Introduction
• Similar cells with a common function are called
tissues.
• The study of tissues is called histology.
• There are four (4) primary or major tissue types:
1.
2.
3.
4.
Epithelial Tissue
Connective Tissue
Muscle Tissue
Nervous Tissue
3
Intercellular Junctions
Tight junctions
• Close space between cells
• Located among cells that form
linings. E.g: Epithelial lining of
the bladder
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Cell membrane
Tight junction
Desmosomes
• Form “spot welds” between cells
• Located among outer skin cells.
•Cell to cell adhesion E.g cardiac tissues
Gap junctions
• Tubular channels between cells
•Transfer of subst. from one cytoplasm
To another.
• Located in cardiac muscle cells
Cell membrane
Desmosome
Cell membrane
Gap junction
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Epithelial Tissue
• General characteristics:
• Cover organs and the body
• Line body cavities
• Line hollow organs
• Have a free surface
• Have a basement membrane
• Are avascular
• Cells readily divide
• Cells tightly packed
• Cells often have desmosomes
• Function in protection, secretion, absorption, and excretion
• Classified according to cell shape and number of cell layers
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Epithelial Tissue
•Simple squamous:
• Single layer of flat cells
• Substances pass easily through
• Line air sacs
• Line blood vessels
• Line lymphatic vessels
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Epithelial Tissue
•Simple cuboidal:
• Single layer of cube-shaped cells
• Line kidney tubules
• Cover ovaries
• Line ducts of some glands e.g Thyroid gland
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Epithelial Tissue
• Simple columnar:
• Single layer of elongated cells
• Nuclei usually near the basement
• Membrane at same level
• Sometimes possess cilia
• Sometimes possess microvilli
• Often have goblet cells
• Line uterus, stomach, intestines
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Epithelial Tissue
•Pseudostratified columnar:
• Single layer of elongated cells
• Nuclei at two or more levels
• Appear striated
• Often have cilia
• Often have goblet cells
• Line respiratory passageways
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Epithelial Tissue
•Stratified squamous:
• Many cell layers
• Top cells are flat
• Can accumulate keratin
• Outer layer of skin
• Line oral cavity, vagina, and anal canal
•
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Epithelial Tissue
• Stratified cuboidal:
• 2-3 layers
• Cube-shaped cells
• Line ducts of mammary glands, sweat glands,
salivary glands, and the pancreas
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Epithelial Tissue
• Stratified columnar:
• Top layer of elongated cells
• Cube-shaped cells in deeper layers
• Line part of male urethra and part
of pharynx
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Epithelial Tissue
• Transitional:
• Many cell layers
• Cube-shaped and elongated cells
• Line urinary bladder, ureters, and part of urethra
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Glandular Epithelium
• Composed of cells that are specialized to produce and secrete
substances
• There are two (2) types:
• Endocrine glands are ductless (key word: hormone)
• Exocrine glands have ducts
• Unicellular exocrine gland:
• Composed of one cell
• Goblet cell
• Multicellular exocrine gland:
• Composed of many cells
• Sweat glands, salivary glands, etc.
• Simple and compound
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Summary of Epithelial Tissue
• Epithelial Tissue- Simple ( Uni-layered) or Stratified ( Multi-layered)
• Simple epithelium further divided into 1. Squamous 2. Columnar 3. Cuboidal
 Squamous- Alveoli lining, endothelium (blood vessel) & endocardium
 Columnar ( simple columnar and Ciliated columnar)
 Simple columnar e.g Mucus membrane of the stomach and large Intestine
 Ciliated Columnar e.g Small Intestine, respiratory tract, and uterus and uterine tube
 Cuboidal e.g duct of the glands, thyroid gland
 Multi-layered or stratified
 Stratified squamous (non-keratinized) e.g Oral cavity, Pharynx and oesophagus
 Stratified squamous ( Keratinized ) ee.g..g Skin
 Pseudostratified columnar and stratified columnar e.g Male Urethra, Auditory tube,
trachea
 Stratified cuboidal e.g Mammary gland, sweat gland, salivary
 Transitional Epithelial e.g Urinary tracts, renal pelvis, ureter, urethral
 Glandular Epithelial – Endocrine and Exocrine gland
 Exocrine-Unicellular and Multicellular
 Types of glandular secretions e.g Merocrine, Apocrine and Holocrine
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Structural Types of
Exocrine Glands
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Tissue surface
Duct
Secretory portion
Simple tubular Simple branched
tubular
Compound tubular
Simple coiled
tubular
Simple branched
alveolar
Compound alveolar
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Types of Glandular Secretions
• Merocrine Glands • Apocrine Glands
• Fluid product
• Salivary glands
• Pancreas gland (?)
• Sweat glands
• Holocrine Glands
• Cellular product
• Portions of cells
• Mammary glands
• Ceruminous glands
• Secretory products
• Whole cells
• Sebaceous glands
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Intact
cell
Secretion
Pinched off
portion of cell
(secretion)
Disintegrating cell
and its contents
(secretion)
New cell
forming by
mitosis and
cytokinesis
(a) Merocrine gland
(b) Apocrine gland
(c) Holocrine gland
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Connective Tissues
• General characteristics:
• Most abundant tissue type
• Many functions:
• Bind structures
• Provide support and protection
• Serve as frameworks
• Fill spaces
• Store fat
• Produce blood cells
• Protect against infections
• Help repair tissue damage
• Have a matrix
• Have varying degrees of vascularity
• Have cells that usually divide
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Connective Tissue
Major Cell Types Present
• Fibroblasts
• Fixed cell
• Most common cell
• Large, star-shaped
• Produce fibers
• Macrophages
• Wandering cell
• Phagocytic
• Important in injury or
infection
• Mast cells
• Fixed cell
• Release heparin
• Release histamine
•Wound healing and immune tolerance
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Connective Tissue
Fiber Types Present
• Collagenous fibers
• Thick
• Composed of collagen
• Great tensile strength
• Abundant in dense CT
• Hold structures together
• Tendons, ligaments
• Elastic fibers
• Bundles of microfibrils
embedded in elastin
• Fibers branch
• Elastic
• Vocal cords, air passages
• Reticular fibers
• Very thin collagenous fibers
• Highly branched
• Form supportive networks
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Connective Tissues
• Connective Tissue Proper:
• Loose connective tissue
• Adipose tissue
• Reticular connective tissue
• Dense connective tissue
• Elastic connective tissue
• Specialized Connective Tissue:
• Cartilage
• Bone
• Blood
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Connective Tissue Types
•Loose Connective Tissue
• Mainly fibroblasts
• Fluid to gel-like matrix
• Collagenous fibers
• Elastic fibers
• Bind skin to structures
• Beneath most epithelia
• Blood vessels nourish
nearby epithelial cells
• Between muscles
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Connective Tissue Types
• Adipose Tissue
• Adipocytes
• Cushions
• Insulates
• Store fats
• Beneath skin
• Behind eyeballs
• Around kidneys and heart
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Connective Tissue Types
• Reticular Connective Tissue
• Composed of reticular fibers
• Supports internal organ walls
• Walls of liver, spleen, lymphatic
organs
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Connective Tissue Types
• Dense Connective Tissue
• Packed collagenous fibers
• Elastic fibers
• Few fibroblasts
• Bind body parts together
• Tendons, ligaments, dermis
• Poor blood supply
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Connective Tissue Types
• Elastic Connective Tissue
• Abundant in elastic fibers
• Some collagenous fibers
• Fibroblasts
• Attachments between bones
• Walls of large arteries, airways,
heart
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Connective Tissue Types
• Bone (Osseous Tissue)
• Solid matrix
• Supports
• Protects
• Forms blood cells
• Attachment for muscles
• Skeleton
• Osteocytes in lacunae
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Connective Tissue Types
• Hyaline cartilage
• Cartilage
• Rigid matrix
• Chondrocytes in lacunae
• Poor blood supply
• Three (3) types:
• Hyaline Cartilage
• Elastic Cartilage
• Fibrocartilage
• Most abundant
• Ends of bones
• Nose, respiratory passages
• Embryonic skeleton
• Elastic cartilage
• Flexible
• External ear, larynx
• Fibrocartilage
• Very tough
• Shock absorber
• Intervertebral discs
• Pads of knee and pelvic girdle
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Connective Tissue Typeshyaline cartilage
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Connective Tissue Typeselastic cartilage
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Connective Tissue Typesfibrocartilage
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Connective Tissue Types
• Blood
• Fluid matrix called plasma
• Red blood cells
• White blood cells
• Platelets
• Transports
• Defends
• Involved in clotting
• Throughout body in blood
vessels
• Heart
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White blood
cell
Red blood
cells
Plasma
(extracellular
matrix of blood)
Platelets
(a)
(b)
b: © The McGraw-Hill Companies, Inc./Al Telser, photographer
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Types of Membranes
• There are four (4) types of epithelial membranes:
1. Serous Membranes
• Line body cavities that
do not open to the
outside
• Reduce friction
• Inner lining of thorax
and abdomen
• Cover organs of thorax
and abdomen
• Secrete serous fluid
2. Mucous Membranes
• Line tubes and organs that
open to outside world
• Lining of mouth, nose,
throat, etc.
• Secrete mucus
3. Cutaneous Membranes
• Covers body
• Skin
4. Synovial Membranes
• Composed entirely of
connective tissue
• Lines joints
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Muscle Tissues
• Skeletal muscle
• General characteristics:
• Muscle cells also called
muscle fibers
• Contractile
• Three (3) types:
• Skeletal muscle
• Smooth muscle
• Cardiac muscle
• Attached to bones
• Striated
• Voluntary
• Smooth muscle
• Walls of organs
• Skin
• Walls of blood vessels
• Involuntary
• Non-striated
• Cardiac muscle
• Heart wall
• Involuntary
• Striated
• Intercalated discs
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Muscle Tissue
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Striations
Cytoplasm
Nucleus
Nuclei
Portion of a
muscle fiber
(a)
(b)
(a)
(b)
b: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer
b: © The McGraw-Hill Companies, Inc./Al Telser, photographer
Skeletal Muscle
Smooth Muscle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Striations
Nucleus
Intercalated
disc
(a)
(b)
b: © The McGraw-Hill Companies, Inc./Al Telser, photographer
Cardiac Muscle
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Nervous Tissue
• Found in brain, spinal cord, and
peripheral nerves
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• Functional cells are neurons
Cellular
process
Cytoplasm
• Neuroglial cells support and
bind nervous tissue components
• Sensory reception
Nucleus
Cell
membrane
Neuroglial
cells
(a)
(b)
b: © Ed Reschke.
• Conduction of nerve impulses
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Any questions?
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