Connective Tissue Supports and Protects Flashcards
(44 cards)
1
Q
What is the major function of connective tissue?
A
- connect tissues and organs
2
Q
characteristics of connective tissues?
A
- ## connective tissue cells are dispersed in a matrix
3
Q
matrix
A
- includes a large amount of extracellular material produced by connective tissue cells that are embedded in it
- plays major role in functioning of this tissue
- major componenet of matrix is: ground substance crisscrossed by protein fibers
- come in vast variety of forms (typically 3 characteristic components): cells, large amounts of amorphous ground substance, and protein fibers
- amount and structure of each component correlates with functino of tissue
4
Q
what is ground substance
A
- major component of matrix in connective cells
- usually fluid, but can also be mineralized and solid (as in bones)
5
Q
what are the functions of connective tissue?
A
- support and connect other tissues (connective tissue sheath that surrounds muscle cells –tendons attach muscle to bones –the skeleton that supports positions of the body)
- protection (fibrous capsules and bones protect delicate organs, skeletal system)
- specialized cells in connective tissue defend body from microorganisms
- transport of fluid, nutrients, waste and chemical messengers (ensured by specialized fluid connective
6
Q
where do connective tissues derive from?
A
- a mesodermal layer of the embryo
7
Q
what is the first connective tissue to develop?
A
- mesenchyme: stem cell line from which all connective tissues are later derived
- clusters are scattered throughout adult tissue and supply the cells needed for replacement and repair after a connective tissue injury
8
Q
what is the second type of embryonic connective tissue that forms?
A
- mucous connective tissue or whartons jelly
- form through the umbilical cord
- tissue is no longer present after birth leaving only scattered mesenchymal cells throughout the body
9
Q
What are the 3 broad categories of connective tissue
A
- connective tissue proper: includes loose connective tissue and dense connective tissue (both tissues have a variety of cell types and protein fibers suspended in viscous ground substance).
10
Q
dense connective tissue
A
- reinforced by bundles of fibers that provide tensile strength, elasticity, protection
11
Q
loose connective tissue
A
- fibers are loosely organized, leaving large spaces in between
12
Q
supportive connective tissue
A
- bone and cartilage
- provide structure and strength to the body and protect soft tissues
- few distinct cell types and densely packed fibers in a matrix characterize these tissues
- in bone: matrix is rigid and described as calcified because of deposited calcium salts
- ex: cartilage (hyaline, fibrocartliage, elastic), bone
13
Q
fluid connective tissue
A
- in lymph and blood, various specialized cells circulate in watery fluids contain salts, nutrients, and dissolved proteins
- ex: blood, lymph
14
Q
connective tissue proper examples
A
loose connective tissue
- areolar
- adipose
- reticular
dense connective tissue
- dense regular
- elastic
- dense-irregular
15
Q
Fibroblasts
A
- present in all connective tissue proper
- most abundant cell in connective tissue proper
- polysaccharides and proteins secreted by fibroblasts combine with extra-cellular fluids to produce a viscous ground substance that, with embedded fibrous proteins, forms an extracellular matrix
16
Q
fibrocyte
A
- less active form of fibroblast
- second most common cell type in connective tissue proper
17
Q
adipocytes
A
- cells that store lipids as droplets that fill most of cytoplasm
- two basic types: white and brown
- brown: store lipids as many droplets, have high metabolic activity
- white: store lipids as single large drop and are metabolically less active
- very effective at storing large amounts of fat
- number and type of adipocytes depend on tissue and location, vary among individuals in the population
18
Q
mesenchymal cell
A
- multipotent adult stem cell
- these cells can differentiate into any type of connective tissue cells needed for repair and healing of damaged tissue
19
Q
macrophage cell
A
- a large cell derived from a monocyte, a type of blood cell, which enters the connective tissue matrix from the blood vessels
- an essential component of the immune system
- when stimulated, releases cytokines, small proteins that act as chemical messengers
- cytokines recruit other cells of immune system to infected sites and stimulate their activites
- roaming or free, move rapidly by amoeboid movement
- engulfs infectious agents and cellular debris
- fixed macrophages are permanent residents of their tissues
20
Q
mast cell
A
- found in connective tissue proper
- has many cytoplasmic granules: contain the chemical signals histamine and heparin
- when irritated or damaged, mast cells release histamine (an inflammatory mediator) – causing vasodilation and increased blood flow at the site of injury/infection along with itching, swelling, and redness (allergic response)
- mast cells are derived from hematopoietic stem cells and are part of the immune system
21
Q
3 main types of fibers secreted by fibroblasts
A
- collagen fibers
- elastic fivers
- reticular fibers
22
Q
collagen fiber
A
- made from fibrous protein subunits linked together to form long and straight fiber
- flexible, have great tensile strength, resist stretching, give ligaments and tendons their characteristic resilience and strength
- fibers hold connective tissues together during the movement of the body
23
Q
elastic fiber
A
- contains protein elastin along with lesser amounts of other proteins and glycoproteins
- main property: after being stretched or compressed, it will return to its original shape
- prominent in elastic tissues found in skin and the elastic ligaments of vertebral columns
24
Q
reticular fiber
A
- formed from same protein subunits as collagen fibers
- fibers remain narrow and arrayed in branching network
- they are found throughout body but are most abundant in reticular tissue of soft organs (liver and spleen), where they anchor and provide structural suport to parenchyma (functional cells, blood vessels, nerves of organ)
25
loose connective tissue
- found between many organs
- acts both to absorb shock and bind tissues together, allows water, salts, and various nutrients to diffuse through to adjacent or imbedded cells and tissues
26
adipose tissue
- consists of mostly fat storage cells, little extracellular matrix
- a large number of capillaries allow rapid storage mobilization of lipid molecules
- white: most abundant, can appear yellow, owes it color to carotene and related pigments from plant food
- contributes mostly to lipid storage and can serve as insulation from cold temps and mechanical injuries
- can be found protecting kidneys and cushioning the back of the eye
- brown: more common in infants, reduced amount of brown fat in adults, mostly in neck and clavicular regions of the body
- many mitochondria in the cytoplasm of brown adipose tissue help explain its efficiency at metabolizing stored fat
- thermogenic (breaks down fat, releases metabolic heat rather than producing ATP - key molecule use in metabolism)
27
areolar tissue
- little specialization
- contains all cell types and fibers previously described and is distributed in a random, web-like fashion
- fills the space between muscle fibers, surrounded blood and lymph, vessels and supports organs in abdominal cavity
- areolar tissue underlie most epithelia and represents the connective tissue component of epithelial membranes
28
reticular tissue
- mesh-like supportive framework for soft organs such as lymphatic tissue, the spleen, liver
- reticular cells produce the reticular fibers that form the network onto which other cells attach
- derives name from reticulus: little net
29
dense connective tissue
- contains more collagen fibers than loose connective tissue does
- displays greater resistance to stretching
- two major categories of dense connective tissue: regular and irregular
- dense regular connective tissue fibers: parallel to each other, enhancing tensile strength and resistance to stretching in direction of fiber orientations
- ligaments and tendons are made of dense regular connective tissue (in ligaments, not all fibers are parallel)
- dense regular elastic tissue contains elastin fibers in addition to collagen fibers
- which allows ligament to return to its original length after stretching
- ligaments and vocal folds between vertebrae in vertebral column are elastic
30
dense irregular connective tissue
- direction of fibers is random
- arrangement gives tissue greater strength in all directions and less strength in one particular direction
- some tissue, fibers crisscross and form a mesh
- in other tissues, stretching in several directions is achieved by alternating layers where fibers run in same orientation in each layer
- layers themselves are stacked at an angle
- dermis of skin is an example of dense irregular connective tissue rich in collagen fibers
- dense irregular elastic tissues giver arterial walls the strength and the ability to regain original shape after stretching
31
2 major types of supportive connective tissue
1 cartliage
2 bone
- allow body to maintain its posture and protect internal organs
32
3 main types of carliage tissue
1 hyaline carliage
2 fibrocarliage
3 elastic carliage
33
hyaline cartliage
- the most common type of cartilage in the body
- consists of short and dispersed collagen fibers and contains large amounts of proteoglycans
- surface of hyaline carliage is smooth
- both strong and flexible, its found in rib cage, nose, covers bones where they meet to form moveable joints
- makes up template of embryonic skeleton before bone formation
- plate of hyaline carliage at ends of bone allow continues growth until adulthood
34
fibrocartliage
- tough because it has thick bundles of collagen fibers dispersed through its matrix
- menisci in knee joint and intervertebral discs are examples
35
elastic cartliage
- contains elastic fibers as well as collagen and proteoglycans
- tissue gives rigid support as well as elasticity
- ear lobes: example
36
Bone
- hardest connective tissue
- provides protection to internal organs and supports the body
- bones rigid extracellular matrix contains mostly collagen fibers embedded in mineralized ground substance containing hydroxyapatite (form of calcium phosphate)
- without collagen -- bones would be brittle and shatter
- without mineral crystals -- bones would flex and provide little support
- highly vascularized tissue
- can recover from injuries quickly
37
osteocytes
- bone cells like chondrocytes are located within lacunae
- history of transverse tissue from long bone shows arrangement of osteocytes in concentric circle around central canal
38
cancellous bone
- looks like sponge under a microscope
- contains empty spaces between trabeculae or arches of bone proper
- lighter than compact bone
- found in interior of some bones at end of long bones
39
compact bone
- solid
- has greater structural strength
40
Fluid connective tissues
- blood and lymph
- cells circulate in liquid extracellular matrix
- the formed elements circulating in blood are derived from hematopoietic stem cells located in bone marrow
- nutrients, salts, and wastes are dissolved in liquid matrix and transported through body
41
erythrocytes
- RBCs
- transport oxygen and some CO2
42
leukocytes
- WBCs
- responsible for defending against potentially harmful microorganisms or molecules
- some WBCs have the ability to cross the endothelial layer that lines blood vessels and enter adjacent tissues
43
Platelets
- cell fragments involved in blood clotting
44
lymph
- contains liquid matrix and WBCs
- lymphatic capillaries are extremely permeable, allowing larger molecules and excess fluid from interstitial spaces to enter lymphatic vessels
- lymph drains into blood vessels, delivers molecules to blood that could not otherwise directly enter the bloodstream
- in this way specialized lymphatic capillaries transport absorbed fats away from intestine and deliver these molecules to the blood
