Connective Tissue

Question 1

how does the ratio of cells to ECM compare in epithelium vs connective?

Answer 1

connective tissue (stroma) has relatively few cells, large amount of intercellular material (ECM)

Question 2

what are the 2 components of the ECM (histology)

Answer 2

fibers (collagen, elastin) and ground substance (ex, proteoglycans)

Question 3

what cell of connective tissue produces BOTH fibers and ground substance

Answer 3

fibroblast

Question 4

superficial fascia is made of

Answer 4

loose irregular connective

Question 5

tendons and ligaments are made of

Answer 5

dense regular connective

Question 6

tendons vs ligaments

Answer 6

tendons: muscle to bone, mostly collagen (don’t want tendons to stretch)

ligaments: bone to bone, more elastic fibers (want ability to return to original shape)

Question 7

where are reticular fibers found?

Answer 7

endomysium (surrounding individual myocytes), endoneurium (nerve fibers), support lymphoid tissue

fine fibers

Question 8

the _____ properties of ground substance in loose connective tissue enable it to resist compression

Answer 8

polyanionic properties - abundance of negatively charged molecules, enable ground substance to hold in Na+ and water to resist compression

Question 9

the hypodermis is what kind of connective tissue

Answer 9

superficial fascia, loose (areolar) connective tissue

functions mostly as packing material

Question 10

usually in sheathes surrounding skeletal muscles from their origins to insertions, or in sheets partitioning skeletal muscles, these tissues are involved in force transmission. What is this type?

Answer 10

deep fascia - dense, fibrous connective tissue

Question 11

function of superficial fascia vs deep fascia

Answer 11

superficial fascia - packing material

deep fascia - involved in force transmission and venous return (in lower extremities)

Question 12

how does turnover of dead components of connective tissue, fibers, and ground substance occur?

Answer 12

components are degraded by macrophages, replaced by fibroblasts (slowly, so healing of tendons and ligaments takes time)

fibroblasts and mesenchymal cells have great capacity to proliferate in response to injury

Question 13

what are the physical/cellular features of fibroblasts (fibrocytes)

Answer 13

produces components of ECM (BOTH fibers and ground substance)

• well-developed RER and Golgi
• fusiform, long, tapered
• central nucleus, prominent nucleolus

Question 14

how do identify mesenchymal cell in EM

Answer 14

undifferentiated cell that retains potential to develop into fibroblasts, smooth muscle cell, adipocytes, others

large nucleus with scant cytoplasm

it’s the cell that doesn’t really look like anything (can’t really see any organelles)

Question 15

appearance of white vs brown adipose tissue

Answer 15

white: energy storage and protection, one large fat droplet inclusion

brown: thermogenesis and energy consumption, lots of mitochondria and multiple small fat droplet inclusions

Question 16

diapedisis =

Answer 16

extravasation

WBC moves through endothelium to enter connective tissue

Question 17

role of macrophage

Answer 17

begin as monocyte, becomes macrophage once it leaves bloodstream and enters connective tissue

functions: phagocytosis, APC (antigen presenting), forms mononuclear phagocyte system

organ specific forms: Kupffer (liver), alveolar dust cells (lungs), microglia (brain), etc

Question 18

what do mast cells contain

Answer 18

secretory granules contains vasoactive substances (histamine)

*if it’s got granules you can see, it’s a mast cell (all other granulocytes have granules that are too small to see)

Question 19

large collections of lymphocytes are found in the ______ of the respiratory and GI tract

Answer 19

lamina propria - sub-epithelial connective tissue

*lymphocytes appear as mostly nucleus with a little bit of cytoplasm

Question 20

B lymphocytes are stimulated to become _____, which produce antibodies

Answer 20

plasma cells

in LM, have basophilic cytoplasm (RER), lightly stained Golgi, snowflake shaped heterochromatin in nucleus

Question 21

function of eosinophils and appearance in imaging

Answer 21

phagocytosis in response to parasitic infections

LM: stain bright orange-red with eosin when in circulation, nucleus has 2-3 lobes

EM: granules have hamburger or football shape

Question 22

function and appearance of neutrophils

Answer 22

“first responders” of inflammation, function in phagocytosis, exude cellular compartments to form NETS (neutrophil extracellular traps) to engulf microbes

nucleus has 3-5 lobes, small cytoplasmic granules

Question 23

match:
cornea or dermis

dense regular or irregular connective tissue

Answer 23

corner - regular dense connective

dermis - irregular dense connective

Question 24

what type of collagen is found in reticular fibers

Answer 24

type III

Question 25

____ are found in wall of arteries

Answer 25

elastic fibers (why artery walls look squiggly)

Question 26

how does cartilage become bone

Answer 26

TRICK question: cartilage does NOT become bone, it is REPLACED by bone if matrix of cartilage calcifies, cells are cut off form nutrient (by diffusion) and die

Question 27

3 types of cartilage

Answer 27

hyaline: end of long bones, end of ribs, nose elastic: where return to shape after stretching is important (ex - epiglottis, external ear) fibrocartilage: where strength is important (intervertebral discs, meniscus of knee, disc of temporomandibular joint)

Question 28

chondroblasts (immature chondrocytes) produce ECM and eventually settle to reside in _____

Answer 28

chondroblasts are known as chondrocytes once they are surrounded by ECM and reside in *lacuna*

Question 29

ECM of cartilage is composed of ______ which draws water and makes it resistant to compression

Answer 29

cartilage proteoglycan GAGs make gourd substance polyanionic - negatively charged, which attracts Na+ and after follows liquids cannot be compressed, making cartilage resistant

Question 30

explain the 2 ways cartilage can grow

Answer 30

1. appositional growth: at periphery (chondrogenic cells divide) 2. interstitial growth: at interior of cartilage (chondrocytes divide) *however, cartilage is nourished by diffusion so growth is limited

Question 31

what important ions are found in bone

Answer 31

Calcium (most of body’s Ca2+ is in bone), PO4-

Question 32

compact vs spongy bone

Answer 32

compact/dense/cortical bone: outer weight-bearing portion (makes up most of appendicular/limb skeleton), mostly calcified spongy/cancellous/trabecular bone: honeycomb shaped *trabeculae*, forms inner regino of bones, contains bone marrow (axial skeleton - ribs and vertebrae - has higher proportion)

Question 33

what kind of bone has trabeculae

Answer 33

spongy/trabecular/cancellous axial skeleton (ribs and vertebrae) has proportionally more than appendicular skeleton (limbs)

Question 34

when calcium is mobilized it comes from _____ bone first

Answer 34

cancellous/compact/dense bone

Question 35

what is the structure of long bone (top to bottom)

Answer 35

epiphysis at ends (closed epiphyseal growth plate) spongy (cancellous bone) at metaphysis (inside epiphysis) diaphysis (shaft) has compact bone and marrow cavity

Question 36

periosteum

Answer 36

outer fibrous layer inner cellular layer - highly vascular, contains osteoprogenitor (stem) cells that give rise to osteoblasts *therefore periosteum has osteoprogenitor capacity*

Question 37

endosteum is identical to ____ but found on the inner surfaces of bone

Answer 37

endosteum = periosteum, but on inner surface of bone

Question 38

how are bones vascular

Answer 38

Haversian system allows passage of blood vessels, lymphatics

Question 39

_____ allow blood vessels in bones to reach interior of bone

Answer 39

Volkman’s canal: in the Haversian system but perpendicular

Question 40

matrix of compact bone

Answer 40

*lamellae*

Question 41

lacuna vs lamellae vs canaliculi

Answer 41

Lacunae are small spaces in the lamellae. Lamellae act as the matrix of the compact bone. Lacunae act as an encase or hollow space for osteocytes or bone cells. Bone canaliculi are microscopic canals between the lacunae of ossified bone.

Question 42

osteoclasts are derived from ______ progenitors

Answer 42

osteoclasts are derived from macrophage-monocyte cell series (NOT mesenchymal as osteoblasts/cytes are) appear as large, multinucleate cells, found at edges of periosteum remodel bone via decalcification, form depressions called *Howship’s lacuna*

Question 43

diarthrotic joints

Answer 43

aka synovial joints, provide freedom of motion closed cavity lined by synovial membrane that produces synovial fluid synovial membrane is only a few cells thick - NOT found on weight-bearing surfaces

Question 44

synovial fluid contains large amounts of _____ that makes it slippery

Answer 44

hyaluronic acid

Question 45

is articular cartilage (hyaline cartilage) on the ends of long bones covered by perichondrium?

Answer 45

no

Question 46

____ are sacs filled with synovial fluid to provide friction-free movement and keep muscles and tendons from rubbing each other

Answer 46

bursa

Question 47

_______ are non-synovial articulations that are more stable and provide less freedom from movement

Answer 47

synarthroses: cartilaginous (symphyses) or fibrous (sutures)