5.2

Question 1

3 basic components of connective tissues:

Answer 1

Cells, Protein fibers, and ground substance.

Question 2

Extracellular matrix

Answer 2

Formed by ground substance and protein fibers.

Question 3

Two cases of cells

Answer 3

resident cells: Stationary cells that are permanently housed within the connective tissue. Help support, maintain and repair the extracellular matrix.

wandering cells: Continuously move throughout the connective tissue proper and are components of the immune system. Help repair damaged extracellular matrix. Primarily types of leukocytes.

Question 4

Resident cell types

Answer 4

Fibroblasts: Relatively flat cells with tapered ends and are the most abundant resident cells in connective tissue proper. They produce the fibers and ground substance components of the extracellular matrix.

Adipocytes: Fat cells, appear in small clusters within some types of connective tissue proper. If large clusters of these cells dominate an area, the connective tissue is called adipose connective tissue.

Mesenchymal cells: a type of embryonic stem cell within connective tissue. If the tissue become damaged, these cells will divide. One cell that is produced replaces the mesenchymal stem cell, while the other cell becomes a committed cell that moves into the damaged area and differentiates into the type of connective tissue that is needed.

Fixed macrophages: relatively large, irregular-shaped cells that are derived from a type of white blood cell. They are dispersed throughout the matrix, where they engulf damaged cells or pathogens. Cells also release chemicals that stimulate the immune system and attract numerous wandering cells to the tissue.

Question 5

3 types of Protein fibers

Answer 5

Collagen fibers, reticular fibers, and elastic fibers.

Question 6

Collagen fibers

Answer 6

Unbranched, cable-like, long protein fibers that are strong, flexible, and resistant to stretching. These fibers are stronger than steel of the same diameter. Collagen comprises about 25% of the body’s protein, and the fibers appear white in fresh tissue, so they often are called white fibers. Numerous in structures such as tendons and ligaments.

Question 7

Reticular fibers

Answer 7

Similar to collagen fibers but much thinner. Contain the same protein subunits as collagen, but their subunits are combined differently. Form a branching, interwoven framework that is tough but flexible. Abundant in the stroma (connective tissue framework) of organs such as the lymph nodes, spleen and liver.

Question 8

Elastic fibers

Answer 8

Contain the protein elastin. The fibers branch and rejoin, and appear wavy. Elastic fibers stretch and recoil easily. Fresh elastic fibers are often called yellow fibers. Elastic fibers are abundant in the skin, arteries, and lungs, to allow them to return to their original shape after being stretched.

Question 9

Ground Substance

Answer 9

Molecular, not cellular, material produced by the connective tissue cells, and it is within this substance that the connective tissue cells and protein fibers reside. Could be viscous (as in blood), semisolid (as in cartilage), or solid (as in bone).

Question 10

Glycosaminoglycans (GAGs)

Answer 10

Polysaccharides that have an attached amine group . GAGs are negatively charged and hydrophilic. They are able to attract and absorb water thus affect the viscosity of the ground substance. When a GAG is linked to a protein it forms an even larger molecule within the ground substance called a proteoglycan.

Question 11

Glycoproteins

Answer 11

Proteins with carbohydrates attached, act as glue to bond connective tissue cells and fibers to the ground substance.

Question 12

Functions of Connective tissue

Answer 12

Physical protection, support and structural framework, binding of structures, storage, transport, and immune protection. Each connective tissue type may perform only some of these functions.

Question 13

Two types of embryonic connective tissue

Answer 13

Mesenchyme
Mucous connective tissue

Question 14

Mesenchyme

Answer 14

The first type of connective tissue to emerge in the developing embryo. It’s mesenchymal cells are dispersed within a gel-like ground substance that contains fine, immature, protein fibers. It is the tissue from which all other connective tissues are formed. Adult connective tissues often house numerous mesenchymal cells that act as stem cells to provide support in the repair of the tissue following damage or injury.

Structure: Stellate or spindle shaped. Viscous fluid with some immature protein fibers
Function: origin for all other connective tissue types
Location: throughout the body of the embryo and fetus

Question 15

Mucous connective tissue aka Wharton’s jelly

Answer 15

Immature protein fibers in this tissue are more numerous than those within Mesenchyme. Mucous connective tissue is located within the umbilical cord only.

Function: Support of structures in umbilical cord

Question 16

Categories of Connective tissue

Answer 16

Connective tissue proper, Supporting Connective tissue, and fluid connective tissue.

Question 17

Connective Tissue proper

Answer 17

Divided into two groups: loose connective tissue and dense connective tissue.

Question 18

Loose connective tissue

Answer 18

Relatively fewer cells and protein fibers than dense connective tissue. The protein fibers are sparse and irregularly arranged, and there is abundant , viscous ground substance. Loose connective tissues act as the body’s “packing material” by supporting and surrounding structures and organs. Loose connective tissue subtypes are well vascularized.

Question 19

Three types of loose connective tissue

Answer 19

Areolar connective tissue, Adipose connective tissue, Reticular connective tissue.

Question 20

Areolar connective tissue:

Answer 20

Structure: Scattered fibroblasts within an abundant viscous ground substance; few elastic and collagen fibers; many blood vessels
Function: Protects tissues and organs, binds skin and some epithelia to deeper tissue; provides space for blood vessels and nerves.
Location: Papillary layer of the dermis (skin); subcutaneous layer (deep to skin); surrounds organs, nerve cells, some muscle cells, and component of blood vessel walls.

Question 21

Adipose connective tissue

Answer 21

Structure: Closely packed adipocytes; nucleus pushed to edge of cell by large fat droplet; contains many blood vessels
Function: Stores energy; insulates, cushion and protects
Location: Subcutaneous layer; surrounds and covers some organs

Question 22

Reticular connective tissue

Answer 22

Structure: Some fibroblasts and numerous white cells within a viscous ground substance, meshwork of reticular fibers
Function: Provides stroma (supportive framework) to lymphatic organs
Location: Spleen, lymph nodes, and red bone marrow

Question 23

Dense connective tissue

Answer 23

Composed primarily of protein fibers and has proportionately less ground substance than loose connective tissue. It also is known as collagenous tissue because collagen fibers usually are the dominant fiber type.

Question 24

3 types of dense connective tissue

Answer 24

Dense irregular connective tissue, dense regular connective tissue, elastic connective tissue

Question 25

Dense regular connective tissue

Answer 25

Structure: Fibroblasts squeezed between densely packed, parallel arrays of collagen fibers; scarce ground substance; limited blood vessels Function: Attached bone to bone (most ligaments) as well as muscle to bone (tendon); resists stress applied in one direction Location: Tendons (attach muscle to bone); ligaments (typically attach bone to bone)

Question 26

Dense irregular connective tissue

Answer 26

Structure: Fibroblasts between densely packed but randomly arranged and clumped collagen fibers; more ground substance than in dense regular connective tissue; extensive blood vessels Function: Withstands stresses applied in all directions; durable Location: Reticular layer of the dermis (skin): epimysium covering skeletal muscle; epineurium covering nerves; periosteum covering bone; perichondrium covering cartilage; some organ capsules.

Question 27

Elastic connective tissue

Answer 27

Structure: Limited fibroblasts between densely packed elastic fibers Function: Allows for stretching and recoil Location: Walls of elastic arteries (eg. the aorta), trachea, vocal chords

Question 28

two types of Supporting connective tissue

Answer 28

Cartilage and Bone Both form a strong, durable framework that protects and supports the soft body tissue,

Question 29

Cartilage

Answer 29

has a firm semisolid extracellular matrix that contains variable amounts of collagen and elastic protein fibers. Mature cartilage cells are called chondrocytes. These cells occupy small spaces called lacunae within the extracellular matrix . They also produce and secrete a chemical that prevents blood vessel growth and formation within the extracellular matrix. More flexible than bone. Present in areas of the body that need support and must withstand deformation. Ie. tip of the nose, outer part of the ear

Question 30

Three major types of cartilage

Answer 30

Hyaline Cartilage, Fibrocartilage, and elastic cartilage

Question 31

Hyaline cartilage

Answer 31

Structure: Irregularly arranged chondrocytes in lacunae; glassy-appearing ground substance; collagen fivers are not visible Function: Provides support; forms most of fetal skeleton Location: Tip of nose, trachea , bronchi, most of larynx, costal cartilage, both the growth plates and articular ends of long bones, most of fetal skeleton

Question 32

Fibrocartilage

Answer 32

Structure: Large chondrocytes in lacunae, numerous, parallel collagen fibers; limited ground substance Function: Weight-bearing cartilage that resists compression; acts as shock absorber in some joints Location: Intervertebral discs, Pubic symphysis, menisci of knee joints

Question 33

Elastic cartilage

Answer 33

Structure: Closely packed chondrocytes in lacunae; abundant elastic fibers that form weblike mesh, limited ground substance Function: Maintains shape while permitting extensive flexibility Location: External ear, epiglottis of larynx

Question 34

Bone connective tissue

Answer 34

Makes up the mass of most of the structures referred to as bones. Bone connective tissue is more solid than cartilage and provides greater support, although it is not as flexible,. Extensively vascularized. Mature bone cells are called osteocytes and are housed within spaces in the extracellular matrix called lacunae.

Question 35

Two forms of bone connective tissue

Answer 35

Compact and Spongy bone.

Question 36

Compact bone

Answer 36

Appears completely solid but is, in fact, perforated by a number of neurovascular canals. Uniform histologic pattern. Compact bone is formed from cylindrical structures called osteons, which display concentric rings of bone connective tissue called lamellae. The lamellae encircle a central canal that houses blood vessels and nerves.

Question 37

Spongy bone

Answer 37

Located within the interior o a bone, it contains a latticework structure of bon connective tissue that is very strong yet lightweight. Some spongy bone houses hematopoietic cells, which form a type of reticular connective tissue that makes blood cells.

Question 38

Bone

Answer 38

structure: osteocytes within lacunae entrapped in calcified extracellular matrix which contains protein fibers (primarily collagen) and ground substance; compact bone organized in osteons; spongy bone is a meshwork that has a different organization from compact bone; both types are well vascularized. Function: provides levers for body movement, supports soft structures, protects organs, stores calcium, and phosphorus ; spongy bone contains hematopoietic tissue Location: Bones of the body

Question 39

Two types of fluid connective tissue

Answer 39

Blood and lymph

Question 40

Blood

Answer 40

Structure: Contains formed elements; dissolved protein within a liquid ground substance called plasma Function: Erythrocytes transport respiratory gases (oxygen and carbon dioxide), white blood cells help protect the body from infectious agents, and platelets help with blood clotting. Dissolved protein fibers coalesce and assist with blood clotting. Plasma transports nutrients, wastes, and hormones throughout the body. Location: Primarily within blood vessels in the heart

Question 41

Lymph

Answer 41

Derived from blood plasma, contains no cellular components or fragments. Is returned to the blood