TISSUES
Chapter 5
TISSUES
A tissue is a group of similar cells that perform a
common function. Each tissue specializes in
performing at least one unique function that
helps maintain homeostasis.
 HISTOLOGY: is the biology of tissues.
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4 PRINCIPAL TISSUE TYPES.
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1. Epithelial tissue: covers and protects the body
surface, lines body cavities, specializes in moving
substance into and out of blood (secretion, excretion,
and absorption), and forms many glands.
2. Connective tissue: Supports body and its parts to
hold and connect it together, transport substances
and protect it from foreign invaders.
3. Muscle Tissue: produces movement; it moves the
body and its parts. Cells are specialized for
contractility and produce movement by shortening
fibers.
4. Nervous Tissue: Most complex. Communication
between parts and integration of activities. Major
function is the generation of complex messages form
coordination of body function.
EMBRYOLOGICAL DEVELOPMENT:
4 Major Tissues appear
early in embryo
development. 1st two
months after conception.
 After conception a series of
cell divisions begin. Single
celled zygote develops into a
hollow ball of cells called the
blastocyst.
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BLASTOCYST:
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Blastocyst implants in wall
of uterus within two weeks.
Cells regroup into 3 primary
germ layers: Endoderm,
Ectoderm and Mesoderm.
This process is called
gastrulation.
GERM LAYERS
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Ectoderm:
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Skin- epidermis
Ectoderm
Lining of mouth, anus, nostrils
Sweat and sebaceous glands
Epidermal derivations – hair and enamel of teeth
Nervous system- brain and spinal cord
Epithelial (sensory ) parts of eyes, nose, ears
MESODERM- MIDDLE
Muscles
 Skeleton (bones and cartilage)
 Blood
 Epithelial lining of blood vessels
 Dermis of skin and dentin of teeth
 Organs – except lining of the excretory and
reproductive systems
 Connective Tissue
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ENDODERM- INNER LAYER
Epithelium (lining) of digestive and respiratory
systems
 Secretory parts of liver and pancreas
 Urinary Bladder
 Epithelial lining of urethra
 Thyroid, parathyroid, thymus
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EPITHELIAL TISSUE
Membranes (covering and lining)
 Functions:
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1. Protection – Skin- tough impermeable epithelial
covering
 2. Sensory- In the eye, skin, nose, and ear .
 3. Secretion- glandular
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Hormones, mucous, digestive juices,
and sweat
4. Absorption- gut (nutrients) and respiratory tract
(oxygen and CO2 exchange)
 5. Excretion- Kidney tubules, concentrates urine
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Cuboidal epithelium
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Ciliated epithelium
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Glandular epithelium
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Columnar epithelium
PSEUDOSTRATIFIED SQUAMOUS
EPITHELIUM
CONNECTIVE TISSUE
Wide spread in or around every organ
of the body. More varied form that
the other tissue
Delicate tissue paper webs
Tough resilient cords
Rigid bones
Fluid –blood
 Function-Supports, connects,
transports and defends
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CHARACTERISTICS OF CONNECTIVE
TISSUE
Made predominantly of matrix of intercellular
material with few cells ie. The matrix of blood is
plasma
Fibers maybe:
Collagenous- white tough and strong
(ligaments)
Reticular- delicate- surrounding organs
Elastic- vocal cords
Elastic fibers contain proteoglycans containing
glucoseamine, hyaluronic acid, chondroitin
sulfate
CONNECTIVE TISSUE
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Classification of connective tissue:
1. Fibrous
a. Loose ordinary- areolar
b. Adipose (fat)
c. Reticular
d. Dense
2. Bone
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3. Cartilage
a. hyaline- covering in respiratory tract
(hyaline membrane disease in premature
babies)
b. fibrocartilage- discs in spine and TMJ
(tempomandibular joint- jaw)
c. Elastic- vocal cords
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4. Blood- connective tissue
a. Erythrocytes- red
blood cells (carriers)
b. Leukocytes- white
blood cells (defenders)
c. Thrombocytesplatelets ( blood clotting)
MUSCLE TISSUE
Skeletal- Muscle to bone
attachment. Voluntary. Tissue is
striated
 Smooth –Muscle in
organs(visceral tissue),
involuntary, non striated
 Cardiac- Wall of heart. Striated
but involuntary. Characteristic is
intercalated disc.
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NERVOUS TISSUE
Brain, Spinal cord and nerves
 Basic cell= Nerve cells (NEURONS) and
neuroglia, which are supporting cells.
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BODY MEMBRANESMembrane refers to a thin sheet like structure that
may have many important functions in the body.
2 major categories:
 1. Epithelial Membranes:
a. Cutaneous-skin – 16% of body weight
b. serous membranes- lines cavities not open to
external environment. Parietal (internal but not
touching organs) and visceral( surrounding organs)
and pericardium
c. Mucous membranes- Line body openings open to
the exterior. (respiratory, digestive, urinary, and
reproductive.) They produce a mucous film, thus the
name.
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BODY MEMBRANES CONT…
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2.Connective Tissue
Membranes
No epithelial components.
Synovial membranescovering joints
Synovial fluid- colorless
lubricating fluid for the
joint