bsc2085 lesson 6

connective tissue

most abundant, widely distributed, and variable type of tissue in which cells occupy less space than matrix

connective tissue characteristics

- specialized cells: more than 1 cell type

- solid extracellular protein fibers found outside cells

- fluid extracellular ground substance: fills space between cells, usually gelatinous, can slow down movement of pathogens infecting tissue

matrix

formed by extracellular components of connective tissue, makes up majority of connective tissue volume/determines tissue's specialized function

functions of connective tissues

binding of organs, support, physical/immune protection, movement, storage, heat production, transport

mucous connective tissue

wharton's jelly, not found in adults, loose connective tissue in many parts of embryo (includes umbilical cord), stem cells may have therapeutic applications

three general categories of connective tissue

connective tissue proper, fluid connective tissues, supporting connective tissues

connective tissue proper

connect and protect (tendons, adipose tissue)

fluid connective tissues

transportation (blood, lymph)

supporting connective tissues

structural support/strength (cartilage, bone)

fibroblasts

produce fibers/ground substance of matrix

macrophages

arise from monocytes, phagocytize foreign material and activate immune system when they sense foreign matter (antigens)

leukocytes/white blood cells

function in immune defense (neutrophils attack bacteria, lymphocytes react against bacteria/toxins/etc)

plasma cells

arise from B lymphocytes and synthesize antibodies

mast cells

secrete heparin to inhibit clotting, histamine to dilate blood vessels

adipocytes

clustered in some fibrous tissues where they dominate (adipose tissue)

layers of CT proper

superficial fascia/hypodermis, deep fascia, subserous fascia

fasciae

body's framework of connective tissue that wrap, support, or surround organs

superficial fascia/hypodermis

provides insulation and padding under integumentary system

deep fascia

resists multidirectional force, wraps organs in capsules, found at end of muscles as tendons, links bones to each other as ligaments

subserous fascia

protects body cavity lining when muscles/muscular organs move

adipose tissue (fat)

tissue in which adipocytes are dominant cell type, space between occupied by areolar tissue, reticular tissue, blood capillaries

white adipose tissue

most abundant/significant type in adults

white fat functions

thermal insulation, cushions organs (eyeballs/kidneys), contributes to body contours, secretes hormones that regulate metabolism

brown adipose tissue

found mainly in fetuses, infants, children

brown fat functions

color comes from blood vessels/mitochondria/mitochondrial enzymes, heat generating tissue, breaks down stored fats to generate heat, heats blood which is circulated through body

fluid connective tissue

contains fluid ground substance (matrix) that suspends mixture of cells (blood, lymph)

blood

contains cellular component (formed elements) and fluid component (blood plasma)

blood formed elements

erythrocytes, leukocytes, platelets

erythrocytes

rbcs, transport o2 and co2

leukocytes

wbcs, defend against infection and disease

platelets

cell fragments involved in blood clotting

fluid elements of connective tissue

extracellular fluid - plasma, interstitial fluid, lymph

plasma

matrix component of blood

interstitial fluid

ecf surounding cells

lymph

ecf collected from interstitial space surrounding tissue cells

cartilage

stiff connective tissue with flexible, rubbery matrix, shape to ear/tip of nose/larynx

cartilage general features

chondroblasts, chondrocytes, avascular, GAGS

chondroblasts

cartilage cells that produce matrix

chondrocytes

cartilage cells that are trapped in lacunae of cartilage matrix

bone (osseous tissue)

calcified connective tissue that composes skeleton, provides support/protection

calcified matrix produced by ___ and maintained by ___

osteoblasts, osteocytes

membranes

cutaneous, mucous (mucosa), serous (serosa), synovial

cutaneous membrane

skin, largest membrane in body

- epidermis resting on dermis (connective tissue)

- relatively dry layer serves protective function

mucous membrane (mucosa)

lines passages that open to external environment (respiratory, digestive)

- sublayers: epithelium, lamina propria (areolar), muscularis mucosa (smooth muscles)

- absorptive, secretory, protective functions, often have goblet cells

serous membrane (serosa)

lines some internal body cavities

- produces serous fluid

synovial membrane

line moving, articulating joint cavities, protects ends of bones at joints

- synoviocytes: cells lining cavity that produces synovial fluid, which acts as lubricant

excitability

cell's ability to respond to stimuli by changing its membrane potential

excitable tissues

nervous and muscular

nervous tissue

specialized for communication by electrical and chemical signals

nervous tissue consist of

neurons (nerve cells), neuroglia (glial cells)

parts of neuron

cell body (houses nucleus/organelles, controls protein synthesis), dendrites (short/branched processes receive/transmit signals), axon/nerve fiber (sends outgoing signals to other cells)

muscular tissue

specialized to contract when stimulated, exerting a physical force on other tissues, organs, or fluids

skeletal muscle

made of muscle fibers, attach to bone, multiple nuclei, striated, voluntary

cardiac muscle

heart wall, non-mitotic, cardiomyocytes, intercalated discs, striated, involuntary

smooth muscle

short/fusiform shaped cells, undergo mitosis, one central nucleus/no striations, involuntary, visceral muscle