Human Anatomy &
Physiology
Chapter 5: Tissues
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II. A. What are tissues? and
C. What is the matrix?
A tissue is a group of similar cells specialized to carry out a
specific function
• In addition to cells, all tissues include a non-living portion
called the extracellular matrix (composition of the matrix
varies from tissue to tissue). The function of the extracellular
matrix is:
 to support the cells within the tissue and
to transmit signals from outside the cells into cells (these
signals influence how cells function
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II. B. The major tissue types & their functions
1. Epithelial – cover & protection of organs, to participate in
secretion, absorption, excretion of various substances, and
sensory reception
2. Connective – bind body parts together, support & protect
softer body parts, and produce blood cells
3. Muscle – produce movement by contraction & relaxation
4. Nervous – sensory reception and transmitting impulses for
coordination, regulation, & integration of body functions
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III. Epithelial Tissues
• Epithelial tissues cover body surfaces & organs; lines inner
surface of body cavities and inner surface of hollow organs;
compose glands.
• Characteristics are:
Lack blood vessels so nutrients must diffuse into epithelium from
underlying connective tissues; anchored to underlying connective
tissue by a thin, non-living layer called the basement membrane
(which is part of the extracellular matrix)
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III. Epithelial Tissues
• Classified according to types of cells
Squamous: thin, flattened cells
Cuboidal: cube-shaped cells
Columnar: tall, elongated cells
• and number of cell layers:
 Simple: single layer
Stratified: two or more layers
Pseudostratified: a single layer of cells that appears to be layered
because the cell nuclei are a varying levels along a row of aligned
cells
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Squamous Epithelium
Simple Squamous
Stratified Squamous
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Cuboidal Epithelium
Simple Cuboidal
Stratified Cuboidal
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Columnar Epithelium
Simple Columnar
Stratified Columnar
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Pseudostratified vs Stratified
Pseduostratified
Stratified
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III. C. Simple Squamous Epithelium
2. Because substances easily pass through simple
squamous epithelium, it is found where diffusion
and filtration take place. For example:
• alveoli in lungs where gas exchange takes place
• walls of capillaries, linings of blood & lymph vessels
• covers membranes that line body cavities
Because it is so thin & delicate, simple squamous tissue is
easily damaged.
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III. D. Simple Cuboidal Epithelium
2. Simple cuboidal tissue covers the ovaries, lines most of the
kidney tubules and the ducts of certain glands (ex: salivary,
thyroid, pancreas, & liver)
3. The functions of simple cuboidal tissue are secretion and
absorption and, in glands, secretion of glandular products.
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III. E. Simple Columnar Epithelium
1. Simple columnar tissue is a single layer of elongated (more long
than wide) cells that may, or may not, be ciliated (the cilia are in
constant motion so they function to move objects along the surface
if the tissue).
2. Ciliated simple columnar tissue lines the fallopian tubes from the
ovaries to the uterus; non-ciliated simple columnar tissue is found
in the digestive tract.
3. Ciliated cells aid in movement of substances; in the digestive tract,
non-ciliated cells protects underlying tissues, absorbs nutrients, and
secretes various fluids.
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III. F. Pseudostratified Columnar Epithelium
Cilia are a characteristic of pseudostratified columnar
epithelial which lines the passages of the respiratory tract.
• The respiratory tract linings are mucous-covered & sticky in order
to trap dust and microorganisms entering with air. The cilia move
the mucous & its captured particles upward and out of the
respiratory airways.
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III. G . Stratified Squamous Epithelium
1. Cell division takes place in the deeper layers that are closer
to the basal membrane & the nutrient supply of the
underlying connective tissue. the layers are pushed upward
and outward as new cells are produced. As the cells move
outward they become more flattened.
2. S. S. E. forms the outer layer of the skin, & is found in the
lining of the oral cavity, throat, vagina, and anal canal.
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III.H. Transitional Epithelium
• Transitional epithelium is specialized to change in response to
increased tension (in other words, it “stretches”).
• T. E. forms the inner lining of the urinary bladder (where it also forms
a barrier to prevent contents of the urinary system from diffusing
back into the internal environment).
• T. E. also lines the ureters (from kidney to bladder) and part of the
urethra (bladder to outside).
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III.I. Glandular Epithelium
• Glandular epithelium is composed of cells that are specialized to
produce & secrete substances into ducts or into body fluid. (Usually
cuboidal or columnar epithelia.)
Note: exocrine vs endocrine glands
• Exocrine glands secrete their products into ducts that open
onto surfaces (such as the skin or the lining of the digestive
tract).
• Endocrine glands secrete their products into tissue fluid or
blood.
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III.J. Types of Glandular Secretions
• Merocrine
a water, protein-rich fluid product is released through the
cell membrane by exocytosis
ex: salivary glands, sweat glands, pancreatic glands
merocrine glands release secretions without losing any of
the cell’s cytoplasm
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III.J. Types of Glandular Secretions
• Apocrine
The secretions apocrine glands consist of cellular product
& portions of the free end of glandular cells is released
through the cell membrane by exocytosis
ex: mammary glands, ceruminous glands lining the
external ear canal
apocrine glands lose small portions of their bodies during
secretion
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III.J. Types of Glandular Secretions
• Holocrine
entire cells filled with secretory products disintegrate
ex: sebaceous glands of the skin
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IV. Connective Tissues:
Structure &Characteristics
• cells are farther apart than epithelial cells & have an
abundance of extracellular matrix (consistence varies from
fluid to semisolid to solid)
• can usually divide
• varying degrees of vascularity (blood vessels) but usually
have good blood supplies and are well nourished
• Types: bone (most rigid), cartilage (less rigid than bone),
dense connective tissue (more flexible; ex: tendons &
ligaments), adipose tissue, loose connective tissue (aka
areolar tissue), blood (fluid)
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IV. A. Connective Tissues: Functions
• bind structures
• provide support & protection
• serve as frameworks
• store fat
• produce blood cells
• protect against infections
• help repair tissue damage
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IV. Connective Tissues:
Components of Connective Tissue
Cell Type
Tissue Fiber
• Fibroblast – produce fibers
• Macrophages – carry on
phagocytosis
• Mast cells – secrete heparin
& histamine
• Collagenous –tensile
strength
• Elastic – stretches
• Reticular – very thing
collagenous fibers that
provide net-like, delicate
support networks
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IV. B. Connective Tissues:
Cell Type Functions
• Fibroblast
most common “fixed” cells (fixed = not mobile)
produce fibers by secreting protein into the matrix
• Macrophages
aka histiocytes; begin as white blood cells
act as scavengers & defensive cells against foreign particles; they are
phagocytes (“eat” cell!! – engulf & break down foreign particles)
• Mast cells
very large cells found near blood vessels
release heparin (prevents blood clotting) & histamine (promotes reactions
associated with inflammation & allergies)
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IV. C. Collagenous vs Elastic
• Collagenous Fibers
Very strong which allows the tissues to withstand pulling forces
Little ability to stretch
• Elastic Fibers
Great ability to stretch
Not as strong as collagenous fibers
Note: blood supply to dense connective tissue (make up
tendons & ligaments) is poor = SLOW to heal
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IV. D. Ligament vs Tendon
Note: blood supply to dense connective tissue (make up tendons &
ligaments) is poor = SLOW to heal
• BOTH are collagenous fibers
• Ligaments connect bones to bones
• Tendons connect muscles to bones
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IV. E. Adipose Tissue
• Specialized form of loose connective tissue that develops when fat
droplets are stored in the cytoplasm of adipocytes
• Lies beneath the skin between muscles, around the kidneys, behind
the eyeballs, in certain abdominal areas, on the surface of the heart,
and around certain joints.
• Adipose tissue cushions joints & some organs (ex: kidneys); it also
provides insulation and energy storage (in fat molecules)
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IV. F. Types of Cartilage
General Characteristics
• A rigid connective tissue that provides support, frameworks,
and points of attachment ; also forms structural models for
many developing bones
• Has no direct blood supply; nutrients diffuse into cartilage
from surrounding perichondrium
This is reason that torn cartilage heals slowly and why chondrocytes do not
divide frequently
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IV. F. Types of Cartilage
• Hyaline cartilage
Most common; very fine fibers (looks ~ like white glass)
Found on the ends of bones in many joints, soft part of
the nose, & in the supporting rings of the respiratory
passages
Function to cushion shock in joints and as a model for
development & growth of some types of bone)
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IV. F. Types of Cartilage
• Elastic cartilage
More flexible than hyaline due to having a network of
elastic fibers
Provides the flexible framework for external ear (pinna)
and the larynx
• Fibrocartilage
Very tough
Acts as a shock absorber for structures subject to
pressure; for ex: forms pads (intevertabral disc )between
vertebrae and cushions bones in the knee and pelvic
girdle
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IV. G. Bone
1. Bone is the most rigid of the connective tissues:
•
•
Hardness due to the deposition of mineral salts between the
cells
Functions are:




supports body structure
protect vital body parts
provide points of attachment for muscles (making movement possible)
Contains red marrow which forms blood cells and maintains calcium &
phosphorus balance
2. Bone injuries heal relatively quick
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IV. G. Bone
2. Bone injuries heal relatively quick because of good blood
supply. (The central canal of bones contains a blood
vessel.)
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IV. H. Blood (Vascular Connective Tissue)
1. Blood is composed of formed elements (cells)
suspended in a fluid extracellular matrix called
blood plasma.
2. The formed elements (cells) are
• red blood cells (RBCs)
• white blood cells (WBCs)
• platelets (cell fragments)
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IV. H. 3. Connective Tissue Matrix
The connective tissue matrix is the key to connecting cells to tissues:
• it is composed of the basement membrane and the interstitial matrix
(the material between cells)
• serves as a scaffolding to organize cells into tissues
• it relays biochemical signals that control cell division, differentiation,
movement, & migration.
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V. Muscle
A. The characteristic of muscle tissue is its ability to
contract (shorten) in response to stimuli. As they
contract, the muscle fibers pull at their attached
ends and thus move body parts.
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V. Muscle
Skeletal muscle
• long, thread-like cells that have alternating light & dark
striations
• controlled by conscious effort (hence the alternative
description of “voluntary muscle”)
• Skeletal muscle is found in muscles that attach to bone
allowing body movement
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V. Muscle
Smooth muscle
• no striations, shorter than skeletal muscle cells and are more
spindle-shaped
• not controlled by conscious effort – its actions are
involuntary
• comprises the walls of hollow organs such as the stomach,
intestine, urinary bladder, uterus, and blood vessels
• Moves food through the digestive tract, constricts blood
vessels, and empties the urinary bladder
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V. Muscle
Cardiac muscle
• Striated and branched; are joined end-to-end forming
complex networks
• not controlled by conscious effort – its actions are
involuntary
• comprises the bulk of the heart
• pumps blood through the heart chambers and into blood
vessels
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VI. Nervous Tissue
A. The basic cell of nervous tissue is the neuron.
B. Neuroglial cells support and bind cells, carry on
phagocytosis, & help supply nutrients to nerve cells
by connecting them to blood vessels.
C. Nervous tissue senses changes in the internal &
external environment, interprets those changes,
and responds by sending impulses to effectors
(such as muscles, glands, or organs)
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VII. Membranes
Membranes are considered organs because they are
comprised of at least two kinds of tissues. There are 3
major types of membranes:
1. Serous membranes
2. Mucous membranes
3. Cutaneous membranes
A fourth type of membrane, synovial membrane, lines joints such as
the knee.
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VII. Membranes
• Serous membrane
Lines body cavities that lack opening to the outside; form the
lining of the thorax (parietal pleura), and abdomen (parietal
peritoneum), and the organs within these cavities (visceral pleura
& peritoneum)
• Mucous membrane
line cavities that open to the outside of the body; ex: oral & nasal
cavities and the tubes of the digestive, respiratory, urinary, &
reproductive systems
mucous membranes contain goblet cells that secret mucus
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VII. Membranes
• Cutaneous membrane is more commonly referred to
as the skin.
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