ILS 7 Histology of connective Tissue

Question 1

conective tissue

Answer 1

Fibroblast

Question 2

microscopic apperance of collagen type 1 fibers

Answer 2

cord-shaped, run a wavy course parallel to each other, show splitting and joining to form a three-dimensional network

Question 3

reticular fibers microscopic apperance

Answer 3

network-like reticulum, run in small bundles, interwoven to form thin lace-like sheets

Question 4

Elastic fibers microscopic activity

Answer 4

microscopic appearance: fine, dark fibrils, arranged in form of anastomosing bundles

ana is elastic

Question 5

Connestive tissue ground substance

Answer 5

water, glycosaminoglycans [e.g, hyaluronic acid, chondroitin sulphate, dermatan sulphate, and heparan sulphate], proteoglycans, and glycoproteins

usually not visible on microscopic slides-

Question 6

connective tissues cells:

Answer 6

Fibroblast, adipocytes, osteocytes, chrondrocyte, tissue macrophages, mast cells,

Question 7

fibroblast

microscopic appearance:

Answer 7

play an essential role in wound healing

microscopic appearance: dense (heterochromatic) flattened or spindle-shaped nucleus, ↓ cytoplasm

Question 8

Adipocytes

– microscopic appearance:

Answer 8

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

Question 9

Osteocyte

microscopic appearance

Answer 9

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

Question 10

Chondrocytes

– microscopic appearance

Answer 10

Chondrocytes produce and maintain the cartilaginous matrix

– microscopic appearance in various zones of a cartilage:
a) superficial zone

b) middle zone

c) deeper zone

Question 11

Tissue Macrophages

microscopic appearance:

Answer 11

strong phagocytosis

microscopic appearance: resting macrophages are difficult to recognize reliably by light microscopy

Question 12

Mast cells

Answer 12

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)

Question 13

Peripheral blood smear showing circulating mature blood cells:

Answer 13

platelets, Erythrocyte, Eosuniphil, Neutrophil, Basophil, lymphocyte, Monocyte

Question 14

Types of connective tissue

Answer 14

Loose Connective tissue
-areolar loose connective
-Reticular connective
-adipose

dense (reg and irregular) connective tissue

specialized connective tissue

Question 15

Loose connective tissue:

Answer 15

Increased quantity of ground substance, loosely arranged connective tissue fibers, ↑ connective tissue cells, moderately viscous fluid matrix

Question 16

Areolar loose connective tissue:

location

Answer 16

– contain increased quantity of connective tissue fibers

beneath the dermis layer of the skin

Question 17

Reticular loose connective tissue:

location

Answer 17

found in liver, spleen and lymphoid tissue

number of reticular connective tissue fibers containing type III collagen

Question 18

c) Adipose (fatty) loose connective tissue:

location

Answer 18

– 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)

Question 19

Dense connective tissue:

Answer 19

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

Question 20

Dense regular connective tissue:

Answer 20

– regularly organized/arranged and parallel bundles of collagen, and elastic fibers which are spread in one/same direction, very few fibroblasts

Question 21

Dense irregular connective tissue:

Answer 21

– contain irregularly organized and densely packed collagen, and some elastic fibers which are spread in multiple directions, increased fibroblasts (purple stained)

Question 22

Specialized connective tissue

Answer 22

bone, cartilage (hyaline, fibrocartilage, elastic ), blood

Question 23

compact (cortical) bone

Answer 23

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

Question 24

Spongy (cancellous, trabecullar) bone:

Answer 24

– 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

Question 25

Cartilage tissue:

Answer 25

– 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

Question 26

hyaline cartilage

microscopic apperance

Answer 26

ribs

– appears glossy under a microscope (glass-like (hyaline) and translucent cartilage )

Question 27

Elastic cartilage:

microscopic apperance

Answer 27

outer ear, epiglottis

connective tissue fibers appear as dark bundles under a microscope

Question 28

fibrocartilage

microscopic apperance

Answer 28

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

Question 29

Clinical conditions and disorders related to human connective tissues:

Answer 29

tendon tears, bony fractures, muscular compartment syndromes, cartilaginous injury, surgical disruption, and direct inflammation of connective tissues, etc

Question 30

Ehlers-Danlos syndrome is due to

Answer 30

defect in synthesis of collagen (Type I or III)

1,3

Question 31

Scurvy

Answer 31

s caused by a deficiency of vitamin C which is necessary for the synthesis of collagen

Question 32

Major muscle proteins include:

Answer 32

myosin (thick filament), Actin, tropomyosin, troponin, titin

Question 33

Transverse (T) tubules:

Answer 33

pathways for action potential propagation from sarcolemma up to the Sarcoplasmic reticulum

Question 34

sarcomeres

Answer 34

Myosin (thick) and Actin (thin) myofilaments are arranged in striated muscles in the form of repeating units/sections, known as ______

Question 35

Sarcomere microscopic apperance

Answer 35

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

Question 36

Appearance of skeletal muscle tissue under a microscope:

Answer 36

Striated appearance, Multinucleated muscle cells, peripherally placed nuclei

Question 37

Appearance of cardiac muscle tissue under a microscope

Answer 37

Striated appearance, single nucleus, nuclei located centrally in the fiber

Branching network

Intercalated disks with gap junctions

Pacemaker cells

Question 38

Appearance of smooth muscle tissue under a microscope:

characteristics

Answer 38

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