FORM & FUNCTION (Tissues) Flashcards
Association of acinar-myoepithelial-ductal cells:
- Basal lamina: outer layer of all three
- Myoepithelial cells: outside of acinus and intercalated duct
- Acinus
-Acinar cells
-Lumen of acinus
*acinus to intercalated duct to striated duct
Merocine glands:
-exocrine gland
-also called eccrine
-secretion via the exocytosis of materials stored in vesicles
Ex. pancreatic acinar cells
Apocrine glands:
-secretory vesicles pinches off the cell surface
Ex. mammary glands, sweat glands
Holocrine:
-entire cell contents are released
Ex. sebaceous glands
Endocrine and paracrine glands:
-no ducts
-secrete contents into the connective tissue
-secretion carried by blood or lymph (endocrine) or act on adjacent cells (paracrine)
>or both modes could be used by the secretion
Cytocrine:
-secretion of contents from one cell into cytoplasm of another
>phagocytosis of the tips of the melanocyte
Ex. melanocytes transfer melanin into the cytoplasm of keratinocytes
Macroautophagy:
-degradation of melanin
>lighter skin=more rapid
>darker skin=slower
Connective tissue:
-connect other tissues
-provides framework and support
-helps in defense mechanism
-acts as a reservoir of hormones and cytokines
-assist in growth, development, repair and storage
*highly vascularized
Connective tissue origin
-mesodermal
Connective tissue composed of:
-cells
-fibers
-amorphous ground substance
Types of connective tissue:
-embryonic (mesenchyme and mucous connective tissue)
-adult/connective tissue proper
Embryonic connective tissue: Mesenchyme
-present primarily in the embryo
-gives rise to adult connective tissue (including blood)
-irregularly shaped mesenchymal cells and amorphous ground substance
Embryonic connective tissue: Mucous/Gelatinous
-Wharton’s jelly (in the umbilical cord)
-stellate fibroblasts
-viscous, gel-like ground substance that contains collagen and proteoglycans
Connective tissue proper
-in adult organisms
-classified based on nature of components and/or abundance of cells/materials
Connective tissue proper types:
- Loose
- Dense
-Irregular
-Regular - Elastic
- Reticular
- Adipose
Specialized connective tissues:
-cartilage
-bone
-blood
-lymph
Cells:
-resident
-wandering
Resident cells:
-relatively stable
-move less/exhibit no movement
Ex. fibroblasts, myofibroblasts, macrophages, adipose cells, mast cells, mesenchymal stem cells
Wandering cells:
-have migrated to the tissue from the blood in response to specific stimuli
>not always there
Ex. lymphocytes, plasma cells, neutrophils, eosinophils, basophils, monocytes
Fibers:
-present in varying amounts
-produced by fibroblasts
-proteins made of long peptide chains
Structural fibers types:
-collagen fibers
-reticular fibers
-elastic fibers
Collagen fibers:
-principal fiber
-made of collagen (over 27 types)
-most abundant
-provides tensile strength
Reticular fibers:
-forms network around muscle, nerve and adipose tissue
-forms a main part of the basement membrane
-individual type 1 collagen
Elastic fibers:
-made of elastin and fibrillin
-provides elasticity
Fibrous adhesive proteins:
-fibronectin and laminin
*bind structural fibers together and form the matrix
Ground substance:
-cells and fibers are embedded in it
-amorphous
-hydrate gel, due to high water content
-part of ECM
Ground substance contains:
-glycosaminoglycans
-proteoglycans
-plasma constituents
-metabolites
-water
-ions
Extra-cellular matrix (ECM):
-forms a structural support that surrounds the connective tissue cells
ECM components:
-ground substance
-fibers (made of collagen and elastin)
Loose connective tissue:
-most widely found in adult animals
-composed of both resident and wandering cells
-cells are more abundant
-all three fiber types are present
Loose connective tissue primarily found:
-beneath the epithelia that cover the body cavities
-areas where foreign particles come in contact with tissues
Ex. lamina propria
Lamina propria:
-underneath the respiratory and GI epithelium
-loose connective tissue with large number of immune cells
Dense connective tissue:
-more fibers and ground substance than cells
-irregular and regular
Dense irregular:
-random orientation of collagen fiber bundles
-found in GI tract, pleura, spleen, liver, kidney, testis, etc.
Dense regular:
-fibers oriented in a regular pattern/same direction
-found in collagenous tendons and ligaments
Elastic CT:
-abundance of elastic fibers that branch an interconnect
-fibers are surrounded by loose connective tissue
Ex. elastic ligaments
Reticular BT:
-composed of stellate reticular cells
-complex 3D network of reticular fibers
>’holds’ the cells in place
Ex. stroma of lymphatic organs (spleen, lymph node, thymus, etc.)
Adipose tissue types:
-white adipose tissue
-brown adipose tissue
White adipose tissue:
-unilocular adipocytes/fat cells
-surrounded by fibrocytes, collagen and reticular fibers
White adipose functions:
-lipid storage
-hormone and cytokine production
Brown adipose tissue:
-multilocular adipocytes
-present mainly in thoracic cavity, and also seen in large blood vessels in the abdominal cavity
Brown adipose functions:
-storage and energy production
