Connective Tissue
• Found throughout the body; most abundant and
widely distributed of all the tissues
• Four main types:
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–
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Connective tissue proper
Cartilage
Bone
Blood
• Characteristics: Tissue with large matrix inside of
it, rich supply of blood vessels, composed of
many types of cells
Connective Tissue Proper:
Areolar
• Fibers: collagen,
elastic
• Wraps and
cushions all
internal organs
• Attached to all
epithelial tissue
• Dermis: small
layer of areolar
tissue
Connective Tissue Proper:
Dense Regular Tissue
• Dense because the
collagen fibers are
packed together
• Distinct wave: made to
withstand force in one
direction
• Found in tendons and
some ligaments and
aponeuroses
Connective Tissue Proper:
Adipose
• The “spaces” are the cells,
with nuclei squished
against the sides
– The clear parts are oil
droplets
• Function: insulation,
cushions and protects
organs, and reserve fuel
• Found: under skin in the
abdomen, around kidneys
& eyeballs, in breasts
Connective Tissue Proper:
Reticular
• Provides a framework
for white blood cells,
mast cells and
macrophages = all part
of the immune system
– Lymphoid organs:
spleen lymph nodes
and bone marrow
Connective Tissue:
Bone
 Haversian Canal
 a series of tubes around narrow channels formed by
lamellae
 Osteoblast
 Bone forming Cells
 Osteocyte
 an osteoblast that has become embedded within the
bone matrix, occupying a bone lacuna
 Lamella
 Osteoblasts deposit the matrix in the form of thin
sheets which are called lamellae.
 Canaliculi
 Canaliculi provide the means for the osteocytes to
communicate with each other and to exchange
substances by diffusion.
 Lacuna
 In the matrix, osteoblasts become encased in small
hollows within the matrix
 Volkmann’s Canal
 These canals establish connections of the Haversian
canals with the inner and outer surfaces of the bone
Bone (osseous tissue)
• Compact bone: looks
like rings of tree
• Function: structural
support, give body
its shape, act as
attachment points
for muscles
• Location: bones
Connective Tissue: Spongy Bone or
Cancellous Bone
• Doesn’t occur in
ring shape like
compact bone
• Still has lacuna
– *single lacuna
spread out
• Rest of tissue
(pink) is called
trabeculae
Connective Tissue:
Spongy Bone
 Red marrow (consisting
mainly of hematopoietic)
tissue and Red blood cells,
platelets and most white
blood cells arise in red
marrow, found mainly in
the flat bones.
 Yellow marrow (consisting
mainly of fat cells). Yellow
marrow is found in the
hollow interior of the
middle portion of long
bones.
Connective Tissue:
Hyaline Cartilage
• Distinguishing
characteristic:
– Pairs of lacunae
• Supports and
reinforces structures
(like bone), but can
bend
• Found: ends of long
bones, connects ribs
to sternum, found at
end of nose, in
trachea and larynx
Connective Tissue:
Blood
• Mature red blood cells
do not have a nucleus
• WBC: have a nucleus
– Neutrophils and
Lymphocyte,
monocyte (pictured)
• Function: transport
respiratory gases
• Location: in blood
vessels
Muscle Tissue
• Highly specialized to contract and produces
most types of body movement
• Three types of Muscle Tissues:
– Smooth Muscle
– Cardiac Muscle
– Skeletal Muscle
Smooth Muscle Tissue
• Smooth: no striations
• Lines hollow structures:
– airways to lungs,
stomach, intestines,
gallbladder, and urinary
bladder
• Involuntary control:
propels substances
along predetermined
pathways
Skeletal Muscle
• Cells are long, multinucleated, and
striated
• Voluntary control
• Location: in skeletal
muscles attached to
bones or occasionally
to skin
Cardiac Muscle
• Uni-nucleated
• Intercalated discs allow
the cardiac muscle to act
as a unit
• Involuntary control
• Function: propels blood
into circulation as it
contracts
• Forms the bulk of the
wall of the heart
• Found: only in the heart
Nervous Tissue
• 2 main cell types found in nervous tissue
– Neuroglia: functionally support, protect and
insulate neurons and bind them together
– Neurons: respond to stimuli and conduct impulses
to and from all body organs
• Found: Brain, spinal cord, and nerves
Parts of the neuron
• Dendrites: branched processes that
receive stimuli and conduct nerve
impulses toward the cell body. (input
portion of neuron)
• Cell body: contains nucleus and
specialized organelles
• Axon: cytoplasmic extension that
conducts nerve pulses away from the
cell body. (output)
Integumentary System
• Skin (integument) – largest organ of the body
• Accessory organs: hair, glands, and nails
• Roles:
–
–
–
–
–
–
–
Mechanical and chemical protection
Thermal protection
Microorganisms
Prevents water loss
Secretory system (waste products)
Vitamin D synthesis
Cutaneous sense organs
Layers of the skin
• 2 main layers:
– Epidermis: stratified into 4 structural layers (or 5 layers
in palms and soles)
– Dermis: consists of 2 layers
• Hypodermis or superficial fascia (subcutaneous
layer)- not part of the skin, but binds dermis to
underlying organs
Epidermis
Dermis
• Second, deeper part of the skin
• Composed mainly of connective tissue
• Blood vessels, nerves, glands, and hair follicles
are embedded in the dermal tissue.
• Dermis is divided into a superficial papillary
region and a deeper reticular region
Dermis
• Papillary region – more superficial dermal
layer; in contact with epidermis;
– Composed of areolar connective tissue
– Dermal papillae –nipple shaped structures indent
into the epidermis and contain loops of capillaries.
Some dermal papillae contain tactile
receptors called corpuscles of touch or Meissener
corpuscles [4] which are touch receptors.
– Responsible for fingerprints
Dermis
• Reticular layer of
the dermis
– Deepest skin layer
– dense irregular
connective tissue
Hypodermis Layer
• Subcutaneous layer is deep to the dermis and
is not part of the skin
• Consists of areolar and adipose tissues
Glands of the Skin
Several kinds of exocrine glands are associated
with the skin
• Sudoriferous glands or sweat glands empty
their secretions onto the skin surface through
pores or into hair follicles.
• Sweat glands: two main types based on their
structure, location and type of secretion.
– Eccrine and Apocrine
Eccrine Sweat Glands
• Simple, coiled tubular glands are much more
common than Apocrine
• Regulate body temperature through
perspiration/evaporation
• Also plays a role in elimination – perspiration
is diluted urine
Apocrine Sweat Glands
• Found: skin of axilla, groin, anal regions, areolae areas of
the breasts, and bearded areas of the face in men.
• Begin functioning at puberty. In women cells of apocrine
sweat glands enlarge around ovulation and shrink during
menstruation
• Secretions are more viscous (thicker) than eccrine
secretions and contain the same compounds as eccrine
sweat plus lipids and proteins, pheromones.
– Pheromones are chemical signals exuded by many animals -including humans -- that evoke sexual behavior
• Mammary glands are specialized apocrine glands that
secrete milk
Sebaceous glands (oil gland)
• Usually connected to hair follicles
• Secrete sebum which is a mixture of fats, cholesterol,
proteins, inorganic salts and pheromones
• Sebum coats the surface of hairs and prevents excessive
evaporation of water from the skin, keeps the skin soft
and inhibits growth of certain bacteria
• Sebaceous glands are found in the skin all over the
body except for the palms of the hands and the soles of
the feet.
– grasping grip and the traction needed for the soles of the
feet would be compromised
Hair follicle
• Hair follicle surrounds the root and consists of
columns of dead, keratinized cells bonded
together by extracellular proteins
– Hair shaft is the superficial portion of the hair, most of
which projects from the surface of the skin.
– Hair root is the portion of the hair deep to the shaft
that penetrates into the dermis and sometimes into
the subcutaneous layer.
– Arrector pili muscle is the smooth muscle that extends
from the superficial dermis of the skin to the side of
the hair follicle
• Arrector pili muscle is the smooth muscle that
extends from the superficial dermis of the skin
to the side of the hair follicle. [14]
Microscope Slide #21
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Connective Tissue