Unit 1: Connective Tissue Flashcards
What are the 5 types of connective tissue?
- Loose
- Dense
- Cartilage
- Bone.
- Blood
*most abundant tissue in the body
- Depend on relative proportions of ground substance, cells, and fibers
What is connective tissue made of?
Matrix and cells
What is matrix made of?
Ground substance mixed and fibers (collagen, elastic, and reticular)
- Extracellular substance, a product of the cells
- Proportion of matrix to cells varies, usually mostly matrix
Function: provides strength and support to tissue
What are the 6 cell types?
- Fibroblasts (secrete matrix).
- Macrophages (phagocytes).
- WBC
- Plasma (secrete antibodies)
- Mast cells (produce histamine)
- Adipocytes (store lipids)
CT general features
Never on an exposed surface
Vascularized (has blood supply) but varies (lots in adipose, poor in bone)
Fixed and wandering types
CT functions
Binds/supports other tissues
Protects organs
Compartmentalizes structures
Transports
Energy reserve
Healing/fighting infection
Matrix ground substance
Amorphous, homogenous
Liquid, gel, or calcified
Contains glycoproteins
Function: medium for nutrient/waste exchange, shock-absorber, physical barrier against bacteria
3 types of matrix fibers
- Collagenous (white)
- Reticular
- Elastic (yellow)
Collagenous matrix fiber
Most common
Long, thick bundles of collagen in varying amounts (loose in fat, dense in ligaments). Wavy when not stretched
- Thick, strong, flexible, non-elastic
- Excess production of these fibers during healing = scars
- If they attach to tissues abnormally = ‘adhesions’
- When meat is cooked collagen breaks down (tender) when leather is tanned it toughens
Reticular matrix fiber
Networks of very fine threads of collagen
Delicate framework for cells in spleen, liver, lymph, endocrine glands
- May also support vessels, nerves, muscle fibers
Elastic (yellow) matrix fiber
Found in CT of organs that change shape (vocal cords, lungs, skin, blood vessel walls)
- Have elastin protein in coiled bundles
- Typically branched
- Not as strong as collagenous, but stretchy
Fibroblasts (fixed cell)
Produce the fibers and ground substance that make the matrix
- Different types for each type of tissue:
Chondroblasts (cartilage), osteoblasts (bone), fibroblasts (bone)
Fibroblasts (fixed cell)
Large, irregular shaped cells that can reproduce themselves.
- Tend to convert to chondrocytre, osteocyte, fibrocyte when mature (less active, but reversible)
Adipocytes (fixed cell)
Store fat (if in groups = ‘adipose tissue’)
Most common SC, abdominal wall, around kidneys
Reticular cells (fixed cell)
Flat, star-shaped, long
- Form a net if contact each other
- Common in lymp nodes, spleen, bone
- Function: immunity, making reticular fibers
3 types of wandering cells?
- Mast
- Leukocytes
- Macrophages
- Move in and out of CT.
- Protection & repair
Mast cells (wandering)
- Contain large granules of histamine and heparin
- Release these and cause inflammation
- Found near blood vessels
Leukocytes/WBC (wandering)
Circulate in blood, enter tissue in response to infection
- 5 types, some phagocytize (eat) bacteria, other make antibodies to help w/infection
Macrophages (fixed OR wandering)
Very large phagocytes, eat bacteria/dead cells/debris
- Tend to congregate around infection & inflammation
- Different names in different tissues
What are the 2 types of CT proper?
Loose (areolar, adipose, reticular)
Dense (regular, irregular, elastic)
What are the 3 types of specialized CT?
Cartilage (hyaline, elastic, fibro)
Bone (compact, cancellous)
Blood
CT proper
- Most CT in the body.
- Loose/dense
- Fibers differ in protein, but mostly collagen & elastin
- Basic support framework of organs
Areolar CT (Loose)
Most abundant CT
Loosely organized cells & extracellular substances
- Cells: fibroblasts (mostly), macrophages, mast cells, adipocytes, plasma
- Extracellular: collagen, elastic and reticular fibers, ground substance
Location: SC skin, mucous membranes, blood vessels, nerves, muscles, stroma of many organs
- Can tear easily, stretch too much when extracellular fluid is present (‘pitting edema’)
Areolar CT (loose) functions
Cushioning
Elasticity
Strength, continous network within organs.
Nutrition to nearby cells through capillary network
Area for immune system to work
Attachment of skin to underlying tissues
Adipose CT (loose)
- Made of adipocytes and fine network of reticular fibers
- Large and rounded (up to 95% of mass stored as fat -> pushes cytoplasm and nucleus to the side)
- Highly vascularized
- Usually look white, can be yellow
- 2 types: brown & white
Location: SC skin, heart, kidneys, yellow marrow, joint padding, behind eye
Function: energy reserves (store triglycerides), insulation, cushioning
Brown fat (adipose CT)
Generate heat to protect young/hibernating mammals
Internal, not subcutaneous (SC)
Energy used exclusively for heat, none ATP
Very vascular (helps moves heat through body)
Reticular CT (loose)
Made of reticular cells and ONLY reticular fibers
- Matrix + reticular fibers = stroma (organ’s supporting framework)
- Location: spleen, liver, lymph, basal lamina (below epithelial cells)
- Function: binds smooth muscle cells together, forms framework/stroma of organs
How is dense CT different than loose CT?
Fewer cells, ground substance, capillaries than loose
More fibrous elements
Dense regular CT
Composition: fibroblasts (scarce) in rows between bundles of collagen fiber arranged longitudinally
Location: tendons (muscle to bone), ligaments (bone to bone), fascia, aponeuroses (muscle to muscle)
- Poor blood supply, injuries to ligaments and tendons heal slowly
Function: provides strong attachment, collagen fiber bundles are strong and withstand pulling forces in ONLY direction fibers run, still flexible
Dense irregular CT
Composition: fibroblasts (scarce), mostly collagen fibers, some elastic fibers
- Woven in flat sheets with fibers in all direction
- Form capsules around some organs, nerves, and tendons
Location: JOINT CAPSULES, HEART VALVES, skin, fascia, bone, cartilage
Function: strong in all directions (doesn’t tear, still flexible)
Elastic CT (dense)
Composition: fibroblasts (scarce), mostly elastic fibers (kinked and regain shape after stretching), few collagen fibers.
- Fibers aligned parallel OR interwoven
Location: trachea, vocal cords, lungs, elastic arteries, stomach and bladder wall
Function: allows stretching
Difference between tendon/ligament?
Tendon: attach muscle to bone, dense CT, strong
Ligament: attach bone to bone, elastic CT, stretchy
2 types of specialized CT
Hemopoietic/blood
Support (cartilage [hyaline/elastic/fibro], bone [compact/cancellous)
Support (bone and cartilage) specialized CT general characteristics
- Solid, flexible, strong extracellular matrix
- Cells contained in macunae (matrix cavities)
- External covering (periosteum or perichondrium) that can generate new tissue
Cartilage general characteristics (specialized CT)
Compostion: chondrocytes (cartilage cells) in lacunae (little spaces) in a matrix of ground substance (‘glycosaminoglycans’) and fibers (collagen & elastin)
- Stiff, plastic matrix that can lubricate and bear weight
- Found in areas that require support and movement (skeleton & joints)
- Give bones a smooth surface to articulate
- No vascular supply, no nerves (pain free!)
- Recieve all nutrients through perichondrium diffusion, which limited thickness
3 types of cartilage (specialized CT)?
Hyaline (joints)
Elastic (nose)
Fibrocartilage (disks)
Hyaline cartilage (specialized CT)
- Composition: chondrocytes in bluish glossy ground substance (firm gel made of chondroitin sulfate and collagen fibers).
*most rigid cartilage - Location: most abundant. ends of long bones, ribs, nose, bronchial tubes
- Function: smooth movement at joints, flexibility and support
- Makes up most of fetal skeleton, turns to bone with development but remains in growth plate of long bones while the animal is growing
Elastic cartilage (specialized CT)
- Compostion: chrondrocytes, cartilage substance (matrix) and elastic fibers.
{similar to hyaline, but MORE elastic fibers} - Location: external ear, epiglottis
- Function: give support and maintain shape, very flexible
Fibrocartilage (specialized CT)
- Composition: scarce chondrocyte groups (rows or clumps) scattered among bundles of collagen fibers in a cartilage matrix
- NO perichondrium
- Location: intervertebral discs, knee joint
- Function: support (cushion, shock absorption) and fusion
Bone/osseous (specialized CT) general characteristics
- Hard, strong, lightweight
- Fiber framework provides strength without brittleness
- Living concrete
- Composition: hard ground substance (inorganic secretion/mineral salt mix & collagen), special cells, blood vessels, nerves
- Location: where weight-bearing and protection is needed
- Function: frame, protects vitals organs, calcium reserve, bone marrow stores fat and produces blood cells
2 types of bone (specialized CT)?
Compact
Cancellous/spongy
Compact bone (specialized CT)
Location: outer layer (cortical bone)
Spongy/cancellous bone (specialized CT)?
- Location: inner area of bone
3 bone cells
- Osteoblasts (make new bone)
- Osteocytes (mature, lives in lacunae)
- Osteoclasts (break down bone)
*bones are constantly being remodelled
Blood general characteristics (specialized CT)
- Composition: formed elements (the 3 blood cell types) in a liquid matrix (plasma)
3 blood cells
- RBC (erythrocyte)
- WBC (leukocyte)
- Platelets (thrombocytes)
Plasma composition
Ground substance = water dissolved with nutrients, ions, hormones, gases.
Extracellular fibers = plasma proteins (important for clotting)
Difference between plasma/serum
Plasma: fluid part of unclotted blood.
Serum: fluid remaning after a clot forms, similar to plasma but lacks clotting factors
Membrane
Thin sheets of tissue that line cavities, cover surfaces, or separate tissues/organs
- Made of:
a) Epithelial tissue & connective tissue
b) Connective only
Epithelial membranes
Epithelial layer overlying a CT layer
3 types: mucous, serous, cutaneous
Mucous membrane (epithelial)
Line body cavities that open to the exterior (GIT, respiratory, reproductive, urinary tracts)
- Have goblet cells that secret mucus on surface
- Mucus = water, electrolytes, mucin (protein)
- Lubricates and traps bacteria (sticky)
Function: secrete mucus, absorb nutrients
Layers of mucous membranes
- Stratified squamous, pseudostratified, or simple columnar epithelium
- Loose CT called lamina propria
- CT called submucosa
Serous membrane (epithelial)
Line internal body cavities and most internal organs.
- Help form mesenteries (supportive ligamints for certain organs ie. stomach)
- Very permeable
Function: secrete serous fluid to reduce friction during movement
- Fluid = transudate (thin, watery, no mucin)
- Becomes more dense with proteins called ‘exudate’ during disease
- If develop abnormally large volume of
fluid, called ‘ascites’ - Called pleural, pericardial, or peritoneal fluid depending on location
Serous membrane layers (epithelial)
Form a potential space between serous membrane lining organ & membrane lining wall of body cavity
1. Parietal layer: lines cavity wall
2. Visceral layer: covers outer surface of organs
- Simple squamous epithelium & loose CT
*painful if damaged, adhesions form between layers
Cutaneous membranes (epithelial)
Skin covering body
- Exposed layer: non-living cells
- Layers: keratinized stratified squamous -> dermis (dense irregular CT - gives strength & elasticity)
3 types of CT membranes
Composed only of CT, usually fibrous.
1. Meninges (fibrous, envelopes brain & spine)
2. Pederichondrium (fibrous, on surface of cartilage, vascularized {cartilage’s sole blood source})
3. Periosteum (fibrous, on surface of bones, vascularized)
Synovial membrane (CT)
Line joints, bursae, tendon sheaths
- Secrete watery synovial fluid that reduces joint friction
- CT only, no epithelial surface
PRISH - signs of inflammation
Pain
Redness
Immobility
Swelling
Heat
Purpose of inflammation
The body’s attempt to:
- Isolate the area
- Clean up
- Prevent further damage
3 stages of tissue healing
- Inflammation
- Organization (granulation)
- Regeneration
5 stages of inflammation
- Vasoconstriction -> vasodilation
- Constriction short, dilation sustained as histamine and heparin bring nutrients - Fluid causes swelling
- Plasma-enzymes, antibodies, proteins
- Irritates nerves causing tenderness - Clot forms
- Platelets clump, fibrin forms a web to isolate and scaffold for repair - Blood cells enter and do their job
- Macrophages and neutrophils clear bacteria then die, making pus - Vasodilation and swelling reduce
- Histamine and heparin drop, return to normal
Granulation tissue
Bright pink, formed under scab
- Composed of collagen fibers
- Lots of small capillaries (look like granules)
- Function: provide nutrients, infection resistant
- Danger on horses of forming ‘proud flesh’ (granulation too thick)
Tissue regeneration
- Epithelialization occurs (granulation tissue replaced by scar tissue)
- Scab falls off
- Fibroblasts make collagen fibers that replace the granulation tissue and contract down (pull edges together)
- Scar: mainly collagen, can disappear, cause problems on constricting organs (heart: pericarditis)
3 healing intentions
- First: wound edges in close apposition, minimal scarring
- Second: wound edges separated, granulation across gap, moderate scarring
- Third: extensive wound gaps, severe scarring
