4 Classes of Tissue in the body:
1) epithelial, 2) connec ve, 3) nervous, 4) muscular
Connec ve ssue is the most abundant and most widely distributed ssue in
the body. Also most variable when looking at it under the microscope
(histologically variable) compared to epithelial ssue.
Categories of Connec ve ssue includes:
- Fibrous Connec ve Tissue (aka Connec ve Tissue Proper).
- 3 sub-classes (specialized classes) — 1) Bone, 2.) Car lage and 3.) Blood
Mesenchyme is type of embryonic connec ve ssue.
General characteris cs of connec ve ssue proper (as opposed to specialized
classes of bone, car lage, blood) — widely sca ered cells with large amount
of matrix. Matrix is a clear gel-like substance (excep ons).
Connec ve Tissue is vascular (has direct blood supply; as opposed to epithelial
ssue which was avascular). Innervated by nerves (like epithelial ssue). Does
not have a free surface (unlike epithelial).
Func ons of Connec ve Tissue:
• Support and protec on (i.e. bone provides support for body and
protec on – skull encloses brain; rib cage and sternum protect heart and
lungs).
• Faciliates movement (skeleton forms framework for movement;
car lage on bone surfaces facilitates movement at joint surfaces).
• Immune defense (some cells func on in phagocytosis – a ack foreign
invaders in body)
• Storage (bones store calcium and phosphorus) (fat is the body’s main
reservoir for energy, so it stores in form of glucose)
• Binding of organs (tendons bind muscle to bone; ligaments bind bone to
bone), fat helps to bind organs (fat around eyes hold eyeball in place; fat
around kidney keeps kidney in place)
• Transporta on (blood is a specialized class of connec ve ssue that
mainly transports gases, nutrients and waste through the body).
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, Development/Origin of Connec ve Tissue — 3 Germ Layers
• 1.) Ectoderm – develops into epidermis
• 2.) Mesoderm(middle) – develops into connec ve ssue
• 3.) Endoderm – innermost layer
Mesenchyme - part of the mesoderm of an embryo which develops into
connec ve ssue, car lage and bone
Mesenchyme will develop into hemocytoblasts (separate lineage), which will develop into
mature blood cell. Mesenchyme will also develop into broblasts
Fibroblasts are undi eren ated immature cells:
• Fibroblasts will further di eren ate into Fibrocytes which will
di eren ate into Fibers that will develop into Connec ve Tissue Proper
• Fibroblasts also di eren ate into Chondroblasts (immature form of a
car lage cell) which will di eren ate and specialize into Chondrocytes
(mature car lage cell) which will eventually develop into connec ve
ssue known as Car lage.
• Fibroblasts will further di eren ate into Osteoblasts (immature bone
cell) which will develop and mature into Osteocytes (mature bone cell)
which will develop into Bone
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1) epithelial, 2) connec ve, 3) nervous, 4) muscular
Connec ve ssue is the most abundant and most widely distributed ssue in
the body. Also most variable when looking at it under the microscope
(histologically variable) compared to epithelial ssue.
Categories of Connec ve ssue includes:
- Fibrous Connec ve Tissue (aka Connec ve Tissue Proper).
- 3 sub-classes (specialized classes) — 1) Bone, 2.) Car lage and 3.) Blood
Mesenchyme is type of embryonic connec ve ssue.
General characteris cs of connec ve ssue proper (as opposed to specialized
classes of bone, car lage, blood) — widely sca ered cells with large amount
of matrix. Matrix is a clear gel-like substance (excep ons).
Connec ve Tissue is vascular (has direct blood supply; as opposed to epithelial
ssue which was avascular). Innervated by nerves (like epithelial ssue). Does
not have a free surface (unlike epithelial).
Func ons of Connec ve Tissue:
• Support and protec on (i.e. bone provides support for body and
protec on – skull encloses brain; rib cage and sternum protect heart and
lungs).
• Faciliates movement (skeleton forms framework for movement;
car lage on bone surfaces facilitates movement at joint surfaces).
• Immune defense (some cells func on in phagocytosis – a ack foreign
invaders in body)
• Storage (bones store calcium and phosphorus) (fat is the body’s main
reservoir for energy, so it stores in form of glucose)
• Binding of organs (tendons bind muscle to bone; ligaments bind bone to
bone), fat helps to bind organs (fat around eyes hold eyeball in place; fat
around kidney keeps kidney in place)
• Transporta on (blood is a specialized class of connec ve ssue that
mainly transports gases, nutrients and waste through the body).
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, Development/Origin of Connec ve Tissue — 3 Germ Layers
• 1.) Ectoderm – develops into epidermis
• 2.) Mesoderm(middle) – develops into connec ve ssue
• 3.) Endoderm – innermost layer
Mesenchyme - part of the mesoderm of an embryo which develops into
connec ve ssue, car lage and bone
Mesenchyme will develop into hemocytoblasts (separate lineage), which will develop into
mature blood cell. Mesenchyme will also develop into broblasts
Fibroblasts are undi eren ated immature cells:
• Fibroblasts will further di eren ate into Fibrocytes which will
di eren ate into Fibers that will develop into Connec ve Tissue Proper
• Fibroblasts also di eren ate into Chondroblasts (immature form of a
car lage cell) which will di eren ate and specialize into Chondrocytes
(mature car lage cell) which will eventually develop into connec ve
ssue known as Car lage.
• Fibroblasts will further di eren ate into Osteoblasts (immature bone
cell) which will develop and mature into Osteocytes (mature bone cell)
which will develop into Bone
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