Lecture 16 9/19/23 Flashcards
What is connective tissue?
tissue whose main function is to provide structure and support for other tissues
What are the different types of connective tissue (for our class)?
-connective tissue proper
-elastic connective tissue
-reticular connective tissue
-adipose tissues
-embryonic connective tissues
What are the characteristics of connective tissue proper?
-basic connective tissue
-holds other tissues together
-main cells are fibroblasts
-extracellular matrix contains collagen and ground substance
What are the characteristics of fibroblasts?
-spindle-shaped
-produce the extracellular matrix
-important in tissue repair
What happens with fibroblasts in tissue repair?
-they transform into myofibroblasts
-have contractile ability
-secrete more extracellular matrix; brings wound together
What are the characteristics of collagen?
-long, strong protein fibers
-provide tensile strength
-different arrangements of a-chains lead to different collagen types
What are the two main types of collagen (for our class)?
-type 1; main structural collagen
-type 3; reticulin
What are the characteristics of type 1/main structural collagen?
-forms ligaments, tendons, dermis, and bone
-shows up as pink fibers on histology
What is the main characteristic of type 3/reticulin?
forms lacy structure of parenchymal organs
What are the characteristics of ground substance?
-complex carbohydrate and protein meshwork
-attracts water to form a gel
-provides compression resistance
-lubricates and hydrates
-provides nutrient and waste transport
What are glycosaminoglycans?
-long, unbranched polysaccharide chains
-complex with proteins to form bottlebrush-shaped proteoglycans in ground substance
What is hyaluronic acid?
a large glycosaminoglycan that will bind multiple proteoglycans to provide additional structure
What are the two structural glycoproteins?
-integrins
-fibronectin
What is the role of integrins?
to be embedded in the cell membrane and attach to various molecules, including fibronectin
What is the role of fibronectin?
bind integrins to collagen
What is the location/purpose of loose connective tissue?
-surrounds vessels/nerves, underlies epithelia, and forms mesentery
-loosely holds tissue together
How can loose connective tissue be identified?
-lots of ground substance
-fewer, irregularly arranged collagen fibers
-sparse fibroblasts
What is the location/purpose of dense irregular connective tissue?
-forms dermis of skin, submucosa of intestines, and organ capsules
-resists forces/stretch in different directions
How can dense irregular connective tissue be identified?
-lots of collagen fibers with many intersecting bundles
-less ground substance
-few fibroblasts
What is the location/purpose of dense regular connective tissue?
-forms tendons, ligaments, and aponeuroses
-resists forces in one direction
How can dense regular connective tissue be identified?
-lots of parallel collagen fibers
-less ground substance
-few fibroblasts
What are the characteristics of elastic connective tissue?
-high proportion of elastin
-cross-linked structure allowing for stretch and coil
What is the location of elastic connective tissue?
-arteries
-nuchal ligament
-vocal cords
How can elastic connective tissue be identified?
-knowing its location
-looking for wavy, dark pink lines in arteries when special stain is used
What are the location and function of reticular connective tissue?
-forms fine network of reticulin fibers to support parenchymal organs
How can reticular connective tissue be identified?
-need reticulin stain
-fibers will stain black; nothing else will dye
What are the functions of white adipose tissue?
-energy storage
-impact protection
-insulation
Where can white adipose be found?
almost everywhere in the body
How can white adipose tissue be identified?
-cells are signet-ring shaped
-one large clear lipid droplet
-single large, peripheral nucleus
-occur in clusters/sheets
What are the characteristics of brown adipose tissue?
-found in neonates, rodents, and hibernating animals
-actively generates heat/involved in thermoregulation
-stays separate from white fat
How can brown adipose tissue be identified?
-many small lipid droplets
-occur in sheets
What is mesenchyme?
primitive tissue in embryos
Where can mucous connective tissue be seen?
-in juveniles, around the vessels of the umbilicus
-in adult chickens in the wattles/combs
What are the two types of embryonic connective tissue?
-mesenchyme
-mucous connective tissue
What is muscle tissue?
tissue that specializes in contration/movement
What are the three types of muscle tissue?
-skeletal
-cardiac
-smooth
What is the function of skeletal muscle?
-primarily voluntary movement
-limited involuntary/semi-voluntary movement
How is skeletal muscle organized?
-each myofiber muscle cell unit has hundred of myofibrils and is multinucleated
-myofiber muscle cell units form fascicles
-each muscle muscle contains many fascicles
What are the characteristics of an individual myofibril?
-composed of repeating sarcomeres
-each sarcomere has parallel arrays of actin and myosin
-actin and myosin form visible cross striations
How does skeletal muscle appear in longitudinal sections?
-long, parallel fibers
-peripheral nuclei
-cross striations
How does skeletal muscle appear in transverse sections?
-round/polygonal fibers
-peripheral nuclei
-no visible striations
-possible to see individual myofibrils
What are the characteristics of cardiac muscle?
-forms myocardium
-involved in involuntary movement of the heartbeat
What is the morphology of cardiac muscle?
-branched cardiomyocytes
-one central nucleus per cell
-intercalated discs in between cells
-striated
What are the characteristics of intercalated discs?
-connect adjacent cardiomyocytes
-anchor the myofibrils
-allow for rapid spread of excitatory stimuli
What are purkinje cells?
cardiomyocytes that specialize in conduction of electrical signals
How does cardiac muscle appear in longitudinal sections?
-can see branching
-can see cross striations
-can see intercalated discs
How does cardiac muscle appear in transverse sections?
-cannot see branching, striations, or intercalated discs
-will see irregular cells with central nuclei
What is the main function of smooth muscle?
involuntary movement
What is smooth muscle involved with?
-GI tract
-uterus
-blood vessels
-skin
-iris
What is the morphology of smooth muscle?
-spindle-shaped cells
-no cross-striations
How will smooth muscle appear in transverse sections?
-variation in cell diameter
-nucleus not seen in all cells
How will smooth muscle appear in longitudinal sections?
-hard to distinguish individual cells
-lots of parallel, oval-shaped nuclei
How can smooth muscle be distinguished from dense irregular CT?
-smooth muscle has nuclei closely packed
-dense irregular CT will have sparse nuclei
