characteristics of connective tissue Flashcards
3 components of connective tissue
- cells
- protein fibers
- ground substance
what do the ground substance and the protein fibers form?
extracellular matrix
what causes the diversity in connectivity tissue (2)
- different types and amounts of protein fibers
- varying proportions of the ground substance
what differentiates connective tissue to epithelial tissue? (2)
- connective tissue aren’t in direct contact with each other
- and are randomly scattered throughout the tissue
what are the functions of connective tissue? (3)
support, protect and bind organs
what are all connective tissue derived from?
an embryonic connective tissue (mesenchyme)
what are the 2 classes of cells of connective tissue proper?
- resident cells
- wandering cells
4 examples of resident cells
- fibroblasts
- adipocytes
- mesenchymal
- fixed macrophages
function of fibroblasts
produce the fibers and ground substance components of the extracellular matrix
what are the functions of resident cells (3)
help support, maintain and repair the extracellular matrix
description of adipocytes (3)
- fat cells
- appear in small clusters of connective tissue proper
- if large clusters of them, the connective tissue is called adipose connective tissue
description of fibroblasts (2)
- flat cells with tapered ends
- most abundant in connective tissue proper
function of mesenchymal
these cells will divide if the connective tissue becomes damaged
description of mesenchymal
type of embryonic stem cell within connective tissue
function of fixed macrophages (2)
- they phagocytize damaged cells or pathogens
- they release chemicals that will stimulate the immune system and attract numerous wandering cells to the tissue when they encounter foreign materials
function of wandering cells (2)
- may help repair damaged extracellular matrix
- protect the body against harmful agents
what are wandering cells primarily types of?
leukocytes (white blood cells)
function of mast cells
- secrete haparin and histamine
what does heparin do
inhibit blood clotting
what does histamine do (2)
dilate blood vessels and increase blood flow
description of fixed macrophages (3)
- large, irregular shaped cells
- derived from a type of white blood cell called monocyte
- dispersed throughout the matrix
description of mast cells
- small, mobile
- usually found close to blood vessels
when are plasma cells formed
when B lymphocytes are activated by exposure to foreign bodies
function of plasma cells
produce antibodies
what are antibodies
proteins which immobilize a foreign material and prevent it from causing further damage
description of free macrophages
mobile, phagocytic cells that wander through the connective tissue
function of free macrophages
function as fixed macrophages, but mobile
2 other leukacytes
- neutrophils (phagocytizes bacteria)
- T-lymphocytes (attacks that materials)
4 examples of wandering cells
- mast cells
- plasma cells
- free macrophages
- other leukacytes
function of protein fibers
strengthen and support the tissue
3 basic types of protein fibers found in connective tissue
- collagen fibers
- reticular fibers
- elastic fibers
description of collagen fibers (6)
- unbranched, ‘cablelike’ long protein fibers
- strong, flexible and resistant to stretching
- comprises about 25% of the body’s protein
- appears white in fresh tissue (called white fibers)
- appear pink in tissue sections stained with hematoxylin and eosin
- numerous in tendons and ligaments
description of reticular fibers
abundant in the stroma (connective tissue framework) of organs such as the lymph nodes, spleen and liver
differences between collagen fibers and reticular fibers (2)
- reticular fibers are much thinner, although they are similar to collagen fibers
- they contain the same protein subunits found in collagen, but their subunits are combined in a different way
what protein do elastic fibers contain
elastin
description of elastic fibers (5)
- fibers branch and rejoin, appear wavy
- stretch and recoil easily
- fresh fibers have a yellowish colour (called yellow fibers)
- appear black when tissue sections are stained with special stains
- abundant in skin, arteries and lungs which allows them to return to their normal shape after being stretched
what is ground substance
noncellular material produced by fibroblasts
where do connective tissue cells and protein fibers reside in
ground substance
what are the 3 consistencies of ground substance
- viscous (blood)
- semisolid (cartilage)
- solid (bone)
what does the viscous nature of the extracellular matrix restrict?
the movement and spread of pathogens
what is GAG
glycosaminoglycans
what are 3 examples of GAGs
- chondroitin sulfate
- heparan sulfate
- hyaluronic acid
what happens when GAG is linked to a protein
it forms a larger molecule, proteoglycan
what is the composition of proteoglycans
> 90% carbs (GAGs)
why do proteoglycans have a large structure
the large number of negative charges in GAGs repel each other, causing the molecule to spread
function of proteoglycans in connective tissue
act as glue to bond connective tissue cells and fibers to the ground substance
functions of connective tissue (6)
- physical protection
- support and structural framework
- binding of structures
- storage
- transport
- immune protection
what are the 2 types of embryonic connective tissue
- mesenchyme
- mucous
what is mesenchyme connective tissue
the first type of connective tissue to emerge in the developing embryo
what are the three connective tissue types
- connective tissue proper
- supporting connective tissue
- fluid connective tissue
what are the 3 types of loose connective tissue
- areolar
- adipose
- reticular
what are the 3 types of dense connective tissue
- denser regular
- dense irregular
- elastic
what are the 2 types of connective tissue proper
- loose connective tissue
- dense connective tissue
what are the 2 types of supporting connective tissue
- cartilage
- bone
what are the 3 types of cartilage
- hyaline
- fibrocartilage
- elastic
what are the 2 types of bone
- compact
- spongy
what are the 2 types of fluid connective tissue
- blood
- lymph
what are the differences between loose and dense connective tissue
- loose has fewer fibers and more ground substance
- dense has more fibers and less ground substance
what is the predominant cell of areolar connective tissue
fibroblast
where can areolar connective tissue be found (3)
- in the skin (papillary layer of the dermis)
- in the subcutaneous layer that is deep to the skin
- surrounds organs, some individual nerve and muscle cells and blood vessels
function of areolar connective tissue (2)
- binds skin and some epithelia to deeper tissue
- protects and surrounds organs, some individual nerve and muscle cells and blood vessels
functions of adipose connective tissue (4)
- stores energy
- insulates
- cushions
- protects
locations of adipose connective tissue (2)
- subcutaneous layer
- surrounds and covers some organs
function of reticular connective tissue
provides stroma (supportive framework) to lymphatic organs
locations of reticular connective tissue (3)
- spleen
- lymph nodes
- red bone marrow
what are the 2 types of adipose connective tissue
- white
- brown
where is brown adipose connective tissue found?
- in newborns
why is dense connective tissue known as collagenous tissue
collagen fibers are the dominant fiber type
what does dense regular connective tissue have few of
blood vessels, so it takes a long time to heal following an injury
functions of dense regular tissue (3)
- attach bone to bone (most ligaments)
- attach muscle to bone (tendons)
- resists stress applied in one direction
location of dense regular tissue (2)
- tendons
- ligaments
function of dense irregular tissue
withstands stresses applied in all directions - durable
location of dense irregular tissue (6)
- most of dermis of skin
- periosteum covering bone
- perichondrium covering cartilage
- epineurium (sheath covering nerves)
- epimysium (sheath covering skeletal muscle)
- some organ capsules (liver, kidneys and spleen)
function of elastic connective tissue
allows for stretching and recoil
location of elastic connective tissue (3)
walls of arteries (aorta), trachea and vocal chords
what is elastic connective tissue composed of
numerous fibroblasts among densely packed elastic fibers
what is dense irregular connective tissue containing
bundles and clumps of collagen fibers that extend in all directions and has an extensive blood supply between the collagen fibers
what does dense regular connective tissue contain
few fibroblasts and limited ground substance, abundant collagen fibers packed tightly and aligned parallel to each other
what does cartilage consist of
a firm, semisolid extracellular matrix that contains variable amounts if collagen and protein fibers
what are mature cartilage cells called
chondrocytes
what are the small spaces within the extracellular matrix called
lacunae
is mature cartilage vascular
no its avascular
how do chondrocytes exchange nutrients and waste products
by diffusion with blood vessels outside the cartilage
what is the most common type of cartilage
hyaline cartilage
what sort of appearance does hyaline cartilage have
clear, glassy
how do chondrocytes and collagen appear in hyaline cartilage
irregularly scattered chondrocytes and collagen within the extracellular matrix not readily observed by light microscopy
functions of hyaline cartilage (2)
- provides support
- forms most of fetal skeleton
locations of hyaline cartilage (6)
- tip of nose
- trachea
- most of larynx
- costal cartilage
- both of the epiphyseal plates and articular ends of long bones
- most of fetal skeleton
functions of fibrocartilage (2)
- resists compression
- acts as a shock absorber in some joints
locations of fibrocartilage (3)
- intervertebral discs
- pubic symphysis
- menisci of knee joints
functions of elastic cartilage
maintains shape while permitting extensive flexibility
locations of elastic cartilage (2)
- external ear
- epiglottis of larynx
what contributes to the durability of fibrocartilage
the densely interwoven collagen fibers
what sort of cartilage is fibrocartilage
a weight-bearing cartilage
what sort of cartilage is elastic cartilage
a flexible, springy cartilage
what differentiates elastic cartilage and elastic connective tissue
- elastic cartilage has a semisolid ground substance and contains chondrocytes
- elastic connective tissue has a fluid ground substance formed by fibroblasts
description of bone connective tissue
makes up most of bones and is more solid than cartilage and provides greater support and not as flexible
what are the organic components of extracellular matrix of bone connective tissue
collagen and glycoproteins
what are the inorganic components of the extracellular matrix of bone connective tissue
a mixture of calcium salts, primarily calcium phosphate
what are bone cells called
osteocytes
what are the two forms of bone tissue
- compact bone
- spongy bone
what are osteons
cylindrical structures which display concentric rings of bone connective tissue (lamellae)
functions of bone (5)
- provides levers for body movement
- supports soft structures
- protects organs
- stores calcium and phosphorus
- spongy bone contains hemopoietic tissue and is the site for hemopoiesis
what is blood
a fluid connective tissue composed of formed elements (inc. cells, erythrocytes and leukocytes, cellular fragments (platelets))
functions of blood (5)
- erythrocytes transport respiratory gases (O2 and CO2)
- leukocytes help protect the body from infectious agents
- platelets help with blood clotting
- dissolved protein fibers coalesce and assist with blood clotting
- plasma transport nutrients, wastes and hormones throughout the body
location of blood
- primarily within blood vessels and in the heart
what is lymph derived from
blood plasma but it contains no cellular components or fragments
