Tissues of the Human Body
Tissues: groups of cells closely associated that have a similar
structure and perform a related function
Histology
 The study of tissues is known as
Histology.
 People who study histology
spend a lot of time looking in
microscopes at the various body
tissues.
4 Types of Tissues
 1. Epithelial
 2. Connective
 3. Muscular
 4. Nervous
 Most organs contain
all 4 types
1. Epithelial Tissue
 Description: coverings (0ne side of epithelial tissue is
always exposed to the outside **which could still be
inside the body**)
 Location: lining and covering organs and body cavities,
the secretory parts of organs and glands, the transport
membranes of capillaries and alveolar sacs, and
membranes which lubricate organs
 Names: according to structure, number of layers,
arrangement, and shape
1. Epithelial Tissue
 Functions
 protection – epidermis
 absorption – lining of intestines
 secretion – ducts of glands
 excretion – epidermis and lining of kidney capillaries
 filtration – lining of kidney capillaries
Epithelial Structures
 Epithelium: layers of cells that line the cavity and cover flat surfaces
 Basement membrane:
 Basal Lamina (protein scaffolding) secreted by epithelial cells
 Reticular Lamina (crossed collagen fiber network) that support and anchor the epithelium
 Connective tissue: supports, connects, or separates different types of tissues
*No blood supply. Nutrients and gases through diffusion.
*Easily regenerates. Sheets of cells quickly regrow.
Microscopy
Epithelial tissue
Basement membrane
 Here is an example of an epithelial tissue. Note that
one side of the tissue is exposed to the outside and the
tissue is connected by a basement membrane.
Classes of Epithelia
 Simple: just one layer or cell shape
 Stratified: multiple layers and cell shapes
Shapes of Epithelia
TYPE
CELL SHAPE
PICTURE
EXAMPLE
Squamous
Squashed
Endothelium (lines blood
vessels)
Mesothelium (serous
lining of coelem)
Cuboidal
Cubed
Walls of glands
Columnar
Columns
*Cilia*
*Goblet Cells*
Lining of the gut tube;
sometimes has cilia
Pseudostratified
Flat cells give rise
to columns
With cilia in respiratory
tubes to move
mucous/particles out of
lungs.
Transitional
Stretches from 6 to
3 cells thick
Lines urinary structures
such as the bladder
Make a chart:
Epithelium
Type
Locations in
Body
Function in
Body
Simple Squamous Epithelium
 Squamous cells are flat. From the side they look
something like a fried egg.
Simple Cuboidal Epithelium
 Secretory and absorptive tissue in glands as well as the
liver and kidneys
Simple Columnar Epithelium
 The secretory and absorptive lining of the Gastro-Intestinal
tract
Stratified Squamous
Epithelium
 The epidermis of the body’s skin
Stratified Cuboidal Epithelium
 Lines ducts
 Found in the ducts of mammary glands, sweat glands,
salivary glands, and the pancreas
Stratified Columnar
Epithelium
 Found in the vas deferens and pharynx.
 Provides a thicker lining for some tubular structures in
the body
Pseudostratified Columnar
Epithelium
 Located at trachea, bronchi, vas deferens
 Help secrete mucus and used for absorption
 Looks like it’s stratified, but it’s not.
 The nuclei appear to be at different levels, however, there is really
only one layer of cells.
Transitional
 Looks like stratified
squamous but the cells
are rounded at both the
base of the tissue and the
section exposed to the
outside.
 Found in the urinary
bladder to allow it to
expand and contract.
Glandular Epithelium
 Can secrete substances into the bloodstream (endocrine
glands) or into ducts (exocrine glands).
Endocrine Glands
 Secrete products into the
bloodstream
 Products are stored in
secretory cells or in follicle
surrounding secretory cells
 Hormones travel to target
organs to increase
response
 No ducts
Exocrine Glands
 Secrete their products into a systems of ducts.
 Classified by how substances are excreted.
 Merocrine: release fluid substances via exocytosis (salivary
and sweat glands)
 Apocrine: lose small portion of the cell body (mammary
and ceruminous glands)
 Holocrine: releases the entire cell (sebaceous glands)
Other Structures: Goblet Cells
 Associated with columnar epithelium.
 Secretes mucous.
Other Structures: Cilia
 Associated with columnar cells.
 Lines respiratory tract.
 Works with goblet cells to move substances along the
cells.
Cilia
Quiz!!
E
Can You Identify the
Classes of Epithelium?
D
A
B
C
2. Connective Tissue
 Description: support using fibers
 Location: universal and most abundant tissue type in body
 Functions:
•
•
•
•
•
•
•
•
Provide support and protection
Serve as frameworks
Fill spaces
Store fat
Underlies epithelium
Produce blood cells
Protect against infections
Help repair tissue damage
 Always originates from mesenchyme (loosely organized undifferentiated mesodermal cells)
 Have varying degrees of vascularity from cartilage (avascular) to bone (which has a rich
blood supply)
 Has non-living extracellular material/matrix (ground substance plus fibers) between its cells
Extracellular Matrix
 Functions:
 medium to dissolve solutes
 transport
 site of chemical reaction
 Fibers
 Collagen
 Reticular fibers
 Elastic
 Ground substance
 Jelly-like material made of sugar-protein molecules (proteoglycans)
 Does not include include the fibers
Cells of Connective Tissues
 Fibroblasts
 Star-shaped cells
 Secretes protein into matrix
producing fibers
(phagocytosis)
 Mast Cells
 Immune cells that release heparin
(an anticoagulant), histamine
(promotes inflammatory reactions)
 Osteocyte
 a bone cell; a mature osteoblast that  Plasma Cells
has become embedded in the bone
 white blood cells that secrete large
matrix
volumes of antibodies
 have an average half life of 25 years,
 originate in the bone marrow
they do not divide
 Neutrophils
 Chondrocyte
 type of phagocyte and are normally
 only cells found in healthy cartilage
found in the bloodstream
 produce and maintain the
cartilaginous matrix, which consists
 Lymphocytes
mainly of collagen
 any of 3 types of white blood cell (T
Cells, B cells, Natural killer cells)
 Macrophages
Fibers of Connective Tissues
• Collagenous fibers
• Thick (stain pink)
• Composed of collagen
• Great tensile strength
• Most abundant in dense CT
• Hold structures together
• Tendons, ligaments
•
Elastic fibers
• Bundles of protein elastin
• All for response to stretch and
distention
• Elastic/rubbery (stain purple)
• Vocal cords, air passages
•
Reticular fibers
• Very thin collagenous fibers
• Highly branched
• Form supportive networks (stain
purple)
• Found in basement membranes
and lymphatic tissues
Connective Tissue Categories
• Fibrous/Proper Connective Tissue (with semi-fluid ground
substance):
• Loose/Areolar connective tissue
• Adipose tissue
• Reticular connective tissue
• Dense (regular and irregular) connective tissue
• Elastic connective tissue
• Supporting/Specialized Connective Tissue:
• Cartilage
• Bone
• Blood
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Connective Tissue Types
• Loose Connective Tissue
•Composition: fluid to gel-like matrix, fibroblasts,
macrophages, collagen and elastic fibers
•Location: beneath most epithelia, between muscles
•Function: diffusion of nutrients; wrap and cushion
organs
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Connective Tissue Types
• Adipose Tissue
• Composition: Adipocytes (fat cells) and reticular
fibers
• Location: beneath skin (subcutaneous layer), behind
eyeballs, around kidneys and heart
• Function: Cushions, protects, insulates, energy
storage
Connective Tissue Types
• Reticular Connective Tissue
• Composition: collagen fibers, fibroblasts, lymphocytes
• Function: supports internal lymphatic organ walls
• Location: walls of liver, spleen, lymphatic organs
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Connective Tissue Types
• Dense Regular Connective Tissue
• Composition: packed collagen fibers, few fibroblasts
• Location: tendons, ligaments
• Function: attachment, tensile strength
**Poor blood supply (slow healing)
Connective Tissue Types
• Dense Irregular Connective Tissue
• Composition: primarily collagen fibers randomly
arranged
• Location: dermis of skin, heart valves & capsules of
organs
• Function: tensile strength
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Connective Tissue Types
• Elastic Connective Tissue
• Composition: elastic fibers, some collagenous fibers,
fibroblasts
• Location: walls of large arteries, airways, heart
• Function: attachments between bones
Specialized Connective Tissue:
Bone
• Bone (Osseous Tissue)
• Composition: Solid matrix, osteocytes in lacunae
• Location: skeleton
•Function: supports and protects, forms blood cells,
attachment for muscles
**Highly vascular= fast healing
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Specialized Connective Tissue:
Cartilage
• Cartilage
• Composition: Rigid matrix; chondrocytes in lacunae; poor
blood supply
• Three (3) types:
• Hyaline Cartilage
• Location: ends of bones, nose, respiratory passages
• Function: flexible support
• Elastic Cartilage
• Location: external ear, larynx
• Function: provide flexibility
• Fibrocartilage
• Location: intervertebral discs, pads of knee and pelvic
girdle
• Function: shock absorber
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Specialized Connective
Tissue: Cartilage
Three (3) types of cartilage:
Hyaline Cartilage
Elastic Cartilage
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Fibrocartilage
Specialized Connective
Tissue: Blood
• Blood
• Composition: fluid matrix
called plasma; red blood
cells; white blood cells;
platelets
• Location: throughout
body in blood vessels; heart
• Function: transports,
defends (immune system),
involved in clotting
(
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Epithelial Tissues Quiz
Review
http://www.biologycorner.com/anatomy/histology/
3. Muscular Tissue
 Function: movement
 Types: Skeletal, Cardiac, Smooth
 Location: throughout body
Cardiac Muscle
 Striated (bands perpendicular to length of cell)
 Have a single, centrally located nucleus and the
muscle fibers branch often
 Where two cardiac muscle cells meet, they form
intercalated discs containing gap junctions and
desmosomes, which bridge the two cells
 Cardiac cells are the only cells that pulsate in
rhythm…slow contractions and does not tire easily
 Can only function under aerobic respiration
Cardiac Muscle
Cardiac Muscle
Smooth Muscle
 Consists of cells with a single, centrally located nucleic
 Cells are elongated/cylindrical with tapered ends and do not
appear striated
 Smooth muscle lines the walls of the blood vessels and
certain organs such as the digestive and urogenital tracts,
where it serves to advance the movement of substances
 Called involuntary muscle because it is not under direct
conscious control…slow and sustained contractions
 Possess gap junctions
 Mainly functions under aerobic respiration
Smooth Muscle
Smooth Muscle
Skeletal Muscle
 Consist of long, cylindrical cells that, under a microscope, appear
striated with bands perpendicular to the length of the cell
 The many nuclei in each cell (multinucleated cells) are located near
the outside along the plasma membrane, which is called the
sarcolemma (muscle cell membrane)
 Skeletal muscle is attached to bones and causes movements of the
body
 Because it is under conscious control, it is also called voluntary
muscle…rapid contractions with great force and tire easily
 No gap junctions present
 Can function under aerobic and anaerobic respiration
Skeletal Muscle
Skeletal Muscle
REVIEW
• Skeletal muscle
• General characteristics:
• Muscle cells are elongated
cells = muscle fibers
• Contractile
• Three (3) types:
• Skeletal muscle
• Smooth muscle
• Cardiac muscle
• Attached to bones
• Striated, multiple nuclei per cell
• Voluntary movement of body
• Smooth muscle
• Walls of hollow organs, skin, walls
of blood vessels
•Non-striated, cells tapered at end,
one nucleus per cell
•Involuntary movement
• Cardiac muscle
• Heart wall
• Striated, one nucleus per cell,
branched ends with intercalated
discs
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•Involuntary movement
Skeletal Muscle Coverings
 Endomysium: thin connective tissue covering muscle fiber
 Perimysium: coarser fibrous membrane covering bundles of muscle
fibers creating a fascicle (bundle of muscle fibers bound together by
connective tissue)
 Epimysium: tough fibrous connective tissue surrounding many fascicles;
outer covering of entire skeletal muscle; blend into tendons or
aponeurosis
 Tendon: cord of dense fibrous tissue attaching a muscle to a bone
 Aponeurosis: fibrous/membranous sheet connecting muscle and the part
it moves
 Fascia: layers of fibrous tissue covering and separating muscles
Skeletal Muscle Anatomy
 Myofilament bundles (actin and myosin)  Myofibril bundles  Muscle
fiber (cell)
 Banding pattern: light and dark bands created by the arrangement of
myofilaments (thick-myosin, thin-actin) in sarcomeres
 Light (I) Bands: contain only actin filaments, parts of two adjacent
sarcomeres
 Has a darker area in the middle, Z disc (midline interruption between
the connections of actin filaments
 Dark (A) Bands: consists of actin and myosin; myosin filaments extend
the entire length of A band;
 has a lighter central area, H zone (H zone has a central line called M
line (protein rods connecting myosin filaments))
Skeletal Muscle Anatomy
4. Nervous Tissue
 Function: control and communication
 Location: brain, spinal cord, nerves
 Cells are called neurons
 Support cells are called glia
Anatomy of a Generalized Neuron
 Cell body: metabolic center (contains typical cell organelles except centrioles—
amiotic)
 Axon: one per cell; process of neuron, conduct impulses away from the cell body
 Dendrites: many per cell; extension of neuron; conduct impulses toward the cell
body
 Axon hillock: axon arises from this cone-like region of cell body
 Axon terminals: 100s to 1000s of brances at terminal end of axon; contains vesicles
of neurotransmitters
 Collateral branch: branch off of an axon
 Synaptic cleft (synapse): separation between axon terminal and next neuron
 Myelin: covering of most long neurons; whitish, fatty substance; protects, insulates,
and speeds up neural transmission
Anatomy of a Generalized
Neuron
Nervous Tissue
Nervous Tissue
Central vs. Peripheral
Nervous System
Central Nervous System
 Consists of: brain and spinal cord
 Functions: integrating center (interpret incoming sensory information) and
command center (issue instructions based on past experience and current
conditions)
 4 types of cells:
 Astrocytes: brace and anchor neurons to capillaries; control chemical
environment in brain by picking up excess ions and recapturing released
neurotransmitters
 Microglia: phagocytes that dispose of dead brain cells and bacteria
 Ependymal: help circulate cerebrospinal fluid that fills cavities and forms
protective cushion around CNS
 Oligodendrocytes: forms myelin sheath; protects and cushions nerves to
speed up nerve transmission speed; produces white matter of brain
Peripheral Nervous System
 Consists of: nerves (cranial and spinal) and ganglia (group of nerve cell
bodies)
 Function: communication lines; linking all parts of the body
 Functional Classifications:
 Sensory/Afferent Division: nerve fibers that carry impulses to the CNS
from receptors located throughout the body
 Motor/Efferent Division: nerve fibers that carry impulses from the CNS
to effector organs bringing about a motor response
 2 types of cells
 Schwann cells: myelinate axons
 Satellite cells: protects and cushions cells of PNS neurons
Practice Tissue Identification
http://www.wisconline.com/objects/index.asp?objID=AP1402
http://www.gwc.maricopa.edu/class/bio201/histop
rc/prac1q.htm
http://teachers.olatheschools.com/~sschultzos/AP
Histology/EpithelialSlidesPracticeQuizA.pdf
http://spot.pcc.edu/anatomy/PDF/Q3_Tissues.pdf
http://bio.rutgers.edu/~gb102/lab_6/601amepithelial.html