ILS 7 Histology of connective Tissue Flashcards
conective tissue
Fibroblast
microscopic apperance of collagen type 1 fibers
cord-shaped, run a wavy course parallel to each other, show splitting and joining to form a three-dimensional network
reticular fibers microscopic apperance
network-like reticulum, run in small bundles, interwoven to form thin lace-like sheets
Elastic fibers microscopic activity
microscopic appearance: fine, dark fibrils, arranged in form of anastomosing bundles
ana is elastic
Connestive tissue ground substance
water, glycosaminoglycans [e.g, hyaluronic acid, chondroitin sulphate, dermatan sulphate, and heparan sulphate], proteoglycans, and glycoproteins
usually not visible on microscopic slides-
connective tissues cells:
Fibroblast, adipocytes, osteocytes, chrondrocyte, tissue macrophages, mast cells,
fibroblast
microscopic appearance:
play an essential role in wound healing
microscopic appearance: dense (heterochromatic) flattened or spindle-shaped nucleus, ↓ cytoplasm
Adipocytes
– microscopic appearance:
are store house for reserve energy (in the form of triglycerides), secret Leptin hormone (regulate hunger)
skin adipocytes assist in thermoregulation by providing insulation
thin rim of cytoplasm, appear as a conspicuous clear space with a very thin border, lipid (round) droplet in the middle of the cell with the nucleus pushed to the periphery, clusters of adipocytes present a foam-like appearance
Osteocyte
microscopic appearance
iii) Osteocytes are mature bone cells
hydroxyapatite crystals (containing calcium carbonate and calcium phosphate) are deposited around them, control activity of osteoblasts (bone forming cells) and osteoclasts (bone destroying cells), increase bone mineralization
– their degeneration leads to increase bone resorption, decrease bone formation, and loss of response to stress
– microscopic appearance: stellate (star) shape, contains a single nucleus
Chondrocytes
– microscopic appearance
Chondrocytes produce and maintain the cartilaginous matrix
– microscopic appearance in various zones of a cartilage:
a) superficial zone
b) middle zone
c) deeper zone
Tissue Macrophages
microscopic appearance:
strong phagocytosis
microscopic appearance: resting macrophages are difficult to recognize reliably by light microscopy
Mast cells
Mast cells release cytokine chemicals during inflammation
– microscopic appearance: cytoplasm packed with secretory granules (contain histamine, and heparin, etc, which are released during physiological, inflammatory, and allergic responses)
Peripheral blood smear showing circulating mature blood cells:
platelets, Erythrocyte, Eosuniphil, Neutrophil, Basophil, lymphocyte, Monocyte
Types of connective tissue
Loose Connective tissue
-areolar loose connective
-Reticular connective
-adipose
dense (reg and irregular) connective tissue
specialized connective tissue
Loose connective tissue:
Increased quantity of ground substance, loosely arranged connective tissue fibers, ↑ connective tissue cells, moderately viscous fluid matrix
Areolar loose connective tissue:
location
– contain increased quantity of connective tissue fibers
beneath the dermis layer of the skin
Reticular loose connective tissue:
location
found in liver, spleen and lymphoid tissue
number of reticular connective tissue fibers containing type III collagen
c) Adipose (fatty) loose connective tissue:
location
– consists of increased number of adipocytes (source of stored excess energy in the form of
triglycerides, and thermogenesis)
location: beneath the skin (subcutaneous fat), around internal organs (visceral fat), in bone marrow (yellow bone marrow), intermuscular (muscular system) and in the breast (breast tissue)
Dense connective tissue:
Decreased quantity of ground substance, densely packed and well-organized connective tissue fibers, decreased number of connective tissue cells, powerfully resistant to axially loaded tension forces, but allow some stretch
Dense regular connective tissue:
– regularly organized/arranged and parallel bundles of collagen, and elastic fibers which are spread in one/same direction, very few fibroblasts
Dense irregular connective tissue:
– contain irregularly organized and densely packed collagen, and some elastic fibers which are spread in multiple directions, increased fibroblasts (purple stained)
Specialized connective tissue
bone, cartilage (hyaline, fibrocartilage, elastic ), blood
compact (cortical) bone
composed of increased number of collagen fibers arranged in OSTEON (cylindrical structures arranged parallel to long bone axis)’, each osteon is formed by LAMELLAE (rings/layers of bone matrix)’ which surrounds the HAVERSIAN CANAL (central space, contain blood vessels)’
also have hydroxyapatite crystals, osteocytes, lacunae
Bone marrow: hematopoiesis
Spongy (cancellous, trabecullar) bone:
– consists of ‘trabeculae (small plates and spikes of bone, give sponge look under the
microscope)’
– contain ‘red (active) or yellow (inactive) bone marrow located in spaces/cavities between
the trabeculae’– site for hematopoiesis (blood cell formation)
– canaliculi connected to bone marrow in spaces between trabeculae to obtain blood supply
Cartilage tissue:
– contain increased collagen fibers (made up of type II collagen), chondroitin sulphate (ground substance), produced by chondroblasts and mature chondrocytes
(2 Car door -(avascular and aneural)
– decreased number of cells, avascular, and aneural
hyaline, elastic cartilage, fibrocatilage
hyaline cartilage
microscopic apperance
ribs
– appears glossy under a microscope (glass-like (hyaline) and translucent cartilage )
Elastic cartilage:
microscopic apperance
outer ear, epiglottis
connective tissue fibers appear as dark bundles under a microscope
fibrocartilage
microscopic apperance
strongest type of cartilage in the human body,
joint capsule, ligaments, pubic symphysis, and intervertebral disc, etc
– appear under a microscope as vague (flimsy) lines arranged in organized fashion with chondrocytes spaced through out
Clinical conditions and disorders related to human connective tissues:
tendon tears, bony fractures, muscular compartment syndromes, cartilaginous injury, surgical disruption, and direct inflammation of connective tissues, etc
Ehlers-Danlos syndrome is due to
defect in synthesis of collagen (Type I or III)
1,3
Scurvy
s caused by a deficiency of vitamin C which is necessary for the synthesis of collagen
Major muscle proteins include:
myosin (thick filament), Actin, tropomyosin, troponin, titin
Transverse (T) tubules:
pathways for action potential propagation from sarcolemma up to the Sarcoplasmic reticulum
sarcomeres
Myosin (thick) and Actin (thin) myofilaments are arranged in striated muscles in the form of repeating units/sections, known as ______
Sarcomere microscopic apperance
cross-striations (striated appearance)
Z-line (Z-disc) form borders of a sarcomere
I (isotropic) band is a zone of thin (actin)
A-band (anisotropic band)
H-zone is relatively lighter region within that do not contain any actin filament
M-line (M-band is present within the H-zone, appears in the middle of the sarcomere, anchor for the thick (myosin) filament
Size of H-zone and I-band becomes shorter during muscle contraction
Appearance of skeletal muscle tissue under a microscope:
Striated appearance, Multinucleated muscle cells, peripherally placed nuclei
Appearance of cardiac muscle tissue under a microscope
Striated appearance, single nucleus, nuclei located centrally in the fiber
Branching network
Intercalated disks with gap junctions
Pacemaker cells
Appearance of smooth muscle tissue under a microscope:
characteristics
Non-Striated appearance
spindle-shaped, single central nucleus, wide middle and tapering ends, cells stick together and are connected by specialized gap junctions, homogeneous eosinophilic cytoplasm, and consisting of myofilaments
caveolae - have Ca
Dense bodies
Calmodulin– replaces Troponin
two subgroups– single-unit and multiunit smooth muscle
