Fibrous Connective Tissues Flashcards
1
Q
- most microscopically and functionally diverse group of tissue and abundant tissue type
- unlike epithelia, it is never normally exposed to the outside environment (separated from the outside by epithelium)
- cells are separated from each other by extracellular matrix
A
connective tissue
2
Q
- composed of gel-like (ground) substance w/ embedded protein fibers
- in the case of bone, the ground substance is calcified into a hard substance
- ground substance holds tissue fluid derived primarily from the blood (carries oxygen, carbon dioxide, nutrients, and wastes)
A
extracellular matrix
3
Q
What are the 4 major groups of connective tissue?
A
- fibrous connective tissue
- cartilage CT
- bone CT
- blood CT
4
Q
What are the functions of connective tissue? (6)
A
- structural framework of the body
- protection (e.g. bones of the skull, dermis of the skin)
- supports and interconnects other tissues
- energy storage (e.g. adipose tissue)
- transports fluids, cells, dissolved chemical through the body
- defense against invasion by microorganisms
5
Q
What are the different cell types in connective tissue? (6)
A
- mesenchymal cells: connective tissue stem cells
- fibroblasts: produce the collagens, elastins, reticular fibers, proteoglycans, and glycoproteins that comprise much of the ECM
- adipocytes: store and release fat; remove lipids from blood and store it and release them back into the bloodstream when needed
- chondrocytes: make both fibrillar component and ground substance found in cartilage
- osteoblasts: make the fibrillar component and calcified substance found in bone; when no longer making bone and trapped within matrix they are called osteocytes
- hematopoietic stem cells: will produce multiple cell types including blood cells and immune cells; immune cells that leave the blood and enter the fibrous connective tissue include: macrophages, mast cells, leukocytes/lymphocytes, and plasma cells
6
Q
What are the different types of hematopoietic immune stem cells that leave the blood and enter the fibrous connective tissue? (4)
A
- macrophages: differentiate from monocytes in the blood; functions are phagocytosis of debris, destroy bacteria, and process materials and present them to other immune cells
- mast cells: secrete chemicals such as histamine that mediate the allergic response and heparin (blood anti-coagulant)
- leukocytes/lymphocytes: immune system cells, several types
- plasma cells: differentiate from B-lymphocytes; produce antibodies that mediate immunity
7
Q
What are the 3 main fiber types within extracellular matrix of connective tissue?
A
- collagen
- elastic fibers
- reticular fibers
8
Q
- type of fiber within the extracellular matrix of connective tissue
- up to 28 different sub-types, with type 1 being the most common
- primarily serve to resist tension (pulling forces)
- vary in thickness and most are fibrillar
A
collagen
9
Q
- type of collagen
- fibrils are aligned and crosslinked to increase tensile strength
- alignment of fibers is responsible for the banding appearance in electron micrographs
- comprised of two collagen alpha 1 chains and a collagen alpha 2 chain that are secreted as procollagen then processed and crosslinked on the cell surface
A
type 1 collagen
10
Q
- disorder caused by dysfunction of collagen
- vitamin C deficiency eventually weakens collagen and connective tissues in the body
(cells must have sufficient levels of vit C to properly cross-link collagen fibers)
- sx: loss of teeth, blood vessel rupture (easy bruising), and poor healing
A
scurvy
11
Q
- disorder caused by dysfunction of collagen
- abnormal collagen synthesis leads to weak collagen fibers (up to 27 different forms) due to mutations in collagen genes or collagen synthesis genes
A
Ehlers-Danlos syndrome
12
Q
- type of fiber within the extracellular matrix of connective tissue
- rubber band like protein fibers that are flexible and recoil back to original state when stretched
- an assembly of tropoelastin, fibulin-1, fibrillin-1, and fibrillin-2
A
elastic fibers
13
Q
- type of fiber within the extracellular matrix of connective tissue
- form a mesh-like, supportive network surrounding structures
- join connective tissue to basement membranes
- form nets surrounding capillaries and support the framework for bone marrow and spleen
A
reticular fibers
14
Q
What are the 2 groups of amorphous ground substances?
A
- proteoglycans and hyaluronans
- glycoproteins
15
Q
- group of amorphous ground substance
- large sugar and sugar-protein molecules
- highly charged and hold water
- primarily responsible for cushioning and resisting compressive forces
A
proteoglycans and hyaluronans
16
Q
- group of amorphous ground substance
- many secreted proteins have some sugar attached to them
- include structural proteins and proenzymes
- carbs are important in protecting the proteins from destruction and can serve as signaling portion of molecules and structural molecules for ground substance to be built on
A
glycoproteins
17
Q
Through what receptors does the cell and ECM interact? (5)
A
- intergrin receptors
- syndecans
- CD44 (receptor for hyaluronans)
- growth factor receptors
- cytokine receptors
18
Q
- cell to ECM receptor
- transmembrane receptors that bind ECM components and initiate intracellular signaling cascades such as tryrosine kinase activity;
- 15-alpha and 8-beta units can form over 20 heterodimeric intergrins types binding specific ECM components
A
integrins
19
Q
- cell to ECM receptor
- co-receptors containing multiple heparan sulfate proteoglycans needed for binding growth factors
A
syndecans
20
Q
- type of connective tissue that is developmentally specific
- rich in mesenchymal stem cells that are multipotent
- rich in ECM
- amount of fibril components is lower than of adult CT
A
embryonic connective tissue
21
Q
- a self-renewing cell population serving as a source for production of differentiated cells throughout life
- differentiate into various cell types, including fibroblasts, muscle cells, osteoblasts, chondroblasts, adipocytes, and others
A
adult mesenchymal stem cells
22
Q
General classes of connective tissue:
(good study tool, don’t worry about cartilage, bone, or blood right now, they will be covered in future lectures/classes)
A
23
Q
- most widespread type of loose connective tissue
- surrounds nerves, muscles, blood vessels, and underlies almost all epithelia (when found immediately beneath membranous epithelia of hollow organs, it is referred to as the lamina propria)
- well vascularized
- functions to support and bind other tissues, hold body fluids, and defends the body against infection
- fixed cells include fibroblasts, adipocytes, and mesenchymal stem cells
- wandering cells include macrophages, lymphocytes, plasma cells, mast cells, and leukocytes
A
areolar connective tissue
24
Q
- type of loose connective tissue
- similar to areolar tissue, but the nutrient-storing capacity is much greater
- contain many adipocytes that remove, store, and release lipids in the bloodsteam
- richly vascularized
- abdundant under skin, surrounding nerves/blood vessels, surrounding organs, and in outer wall of viscera
- provides padding and cushioning, acts as a filler and insulator
A
adipose connective tissue
25
What are the 2 types of adipose connective tissue and what are their functions?
- white fat: energy storage, insulation, cushioning of organs and hormone secretion
- brown fat: key thermogenic tissue found abundantly in newborns, but greatly reduced in adults; contain numerous intracellular fat droplets and are smaller in size than adipocytes in white fat
26
- type of loose connective tissue that is rich in reticular fibers
- forms an open framework to create a labyrinth for holding free cells
- found in bone marrow, lymph nodes, and spleen where the meshwork it forms houses blood cells and immune cells outside the blood and lymphatic vessels
- also found connecting some basement membranes to underlying connective tissue
reticular connective tissue
27
- type of connective tissue that contains very thick and abdundant collagen fibers
- resists extremely strong pulling forces
- fibroblasts are the principle cell type found here
dense connective tissue
28
- type of dense connective tissue
- thick collagen fibers are deposited in a random pattern (e.g. dermis of the skin and fibrous capsules surrounding certain organs like the kidneys, bones, etc.)
dense irregular connective tissue
29
- type of dense connective tissue
- collagen fibers are deposited in a highly regular pattern (e.g. ligaments, aponeuroses, and tendons connecting muscle to bone)
- poorly vascularized
- when not under tension may appear wavy in tissue sections
dense regular connective tissue
30
- type of dense connective tissue
- rich in elastin fibers such as in walls of large blood vessels, surrounding bronchiole tubes, and in certain special ligaments (e.g. ligamentum nuchae)
dense elastic connective tissue
31
- autosomal dominant disorder where elastin is weak due to a mutation in human *FIBRILLIN*-1 gene, whose gene product is a component of elastin fibers
- principle target organs are ocular, skeletal, and cardiovascular systems, which can be life threatening
Marfan's syndrome
32
- combination of epithelia and connective tissue that cover and protect other structures and tissues in the body
- four types: mucous, serous, cutaneous, and synovial
membranes
33
What are the 4 types of membranes and what is their function?
- mucous membranes: line hollow organs (e.g. GI tract, respiratory tract, urinary tract)
- serous membranes: secrete a lubricating fluid resembling serum into the major body cavities (i.e. pleural, pericardial, and peritoneal cavities)
- cutaneous membrane: the skin
- synovial: line moveable joint cavities
