Connective Tissue and Muscle Flashcards
Connective tissue is derived from which embryonic layer?
mesoderm
Functions of Connective Tissue
- Structural support
- Metabolic support (blood vessels, nutrient storage)
- Thermoregulation (brown fat)
- Immune defense (bone marrow)
- tissue repair (wound healing)
How is connective tissue distinguished?
by number and type of cells; type of extracellular matrix
Types of connective tissue
- connective tissue proper
- embryonic connective tissue
- special types (blood, bone marrow, cartilage, bone)
Cell types in connective tissue
- fibroblasts
- myofibroblasts
- adipocytes
- immune cells
Fibroblasts
most common cell type in connective tissue. make all the extracellular matrix components. spindle-shaped cells with elongate nucleus and scant cytoplasm. Surrounded by extracellular matrix
Myofibroblasts
activated and modified fibroblasts that have contractile activity. Important in wound contraction and healing
Extracellular Matrix Components
- fibers
- structural glycoproteins
- ground substance
Types of ECM Fibers
collagen and elastin
Collagen
most common fiber in connective tissue. Stains pink with routine stains. most abundant protein in the body. Provides tensile strength
Types of Collagen
- Type I- fibrous tissue
- Type II- hyaline cartilage
- Type III- reticulin
- Type IV- basement membranes
Elastin
provides for stretch and recoil. Looks like collagen with routine stains. Needs special stains to differentiate it from collagen
Structural Glycoproteins
link proteins to the cell membranes (integrins) to the extracellular matrix fibers (like collagen). Fibronectin, fibrillin, etc. Connect collagen to membrane. Too small to see microscopically
Ground Substance
semi-fluid gel. Seen as empty/clear spaces microscopically. Contains glycosaminoglycans (polysaccharides).
Glycosaminoglycans
hyaluronic acid is the predominant one. Attract water to keep the fluidity of the ground substance. this fluid forms the extracellular fluid. When associated with proteins they are called proteoglycans.
Types of Connective Tissue Proper
- Regular
- Irregular
- Reticular
- Elastic
- Adipose
Regular connective tissue proper
forces are in one direction. Closely-packed, parallel bundles of collagen. Found in tendons and ligaments
Irregular Connective Tissue Proper
forces applied in multiple directions. collagen fibers course in all directions. Found everywhere else
Types of Irregular Connective Tissue Proper
- loose
2. dense
Loose Irregular Connective Tissue Proper
more clear space than fibers. Found surrounding vessels and nerves and forms the mesentery
Dense Irregular Connective Tissue Proper
More fibers than clear space. Found in deep layers of the skin, submucosa of intestines, and organ capsules
Reticular Connective Tissue
predominant fiber type is reticulin. Looks pink with routine stains. Indistinguishable from the typical collagen in routine stains. Need silver stain to see it. Form a delicate branched network that support the cells in parenchymal organs.
Where is reticular connective tissue found?
spleen, lymph node, liver, kidney, bone marrow
Elastic Connective Tissue
predominate fiber type is elastin. Elastin is technically not a type of collagen. Can’t see elastin well with routine stains. Provides flexibility to tissues.
Where is elastic connective tissue found?
blood vessels, external ear, vocal chords, trachea, lung, skin
Adipose Connective Tissue
cells are called adipocytes
White Adipose Tissue
white fat
Functions of White Adipose Tissue
- energy storage
- shock absorption
- insulation/thermoregulation
Where is white adipose tissue found?
- within and around muscle
- subcutaneous
- falciform ligament
- mesentery
- around the kidneys
Shape of White Adipose Cells
signet-ring shaped. Large central lipid droplet which compresses and peripheralizes the nucleus.
Brown Adipose Tissue
Function in thermoregulation (mitochondria produce heat instead of ATP). Cells contain multiple small lipid droplets and lots of mitochondria. The nuclei are plump and round. Lipid droplets will vary in size, even within a cell and within a group of brown fat cells. Found in neonates, rodents, and hibernating animals.
Muscle Functions
- voluntary control (locomotion, controlling bodily functions)
- involuntary control (heart beating, dilation or constriction of arteries, peristalsis in digestive tract, parturition)
Cell membrane of myofibers
sarcolemma
cytoplasm of myofibers
sarcoplasm
Sarcoplasm
contains myofilaments which are anchored to the cell membrane. Actin (thin), myosin (thick), which are connected together and movement of them against each other pulls the cell membrane to move the cell.
Shape of Nucleus of myofibers
oval
Muscle is derived from which embryonic layer?
mesoderm
Types of muscle
smooth, skeletal, cardiac
Smooth Muscle
involuntary control
Where is smooth muscle found?
digestive tract, blood vessels, urinary bladder, bronchi and bronchioles, iris, piloerecti muscles
Smooth Muscle Structure
cells are small compared to skeletal and cardiac muscle. Spindle shaped. 1 nucleus per cell, elongate. Cytoplasm is smooth, no striations
Skeletal Muscle
voluntary control
Where is skeletal muscle found?
muscles, tongue, pharynx, anus, urinary sphincter, extraocular muscles
Skeletal Muscle Functions
locomotion, control of bodily functions (swallowing, urination, defecation)
Skeletal Muscle Structure
largest type of muscle cell. cylindrical. Cytoplasm contains well organized myofilaments which give the muscle the striated appearance. The striations run across the short axis of the fiber. On cross section the cells are round to triangular. Multiple nuclei located peripherally
Hypertrophy
increase in the size of cells
Atrophy
decrease in the size of cells
Cardiac Muscle
involuntary control.
Where is cardiac muscle found?
heart
what is the function of cardiac muscle?
heart contraction
Cardiac muscle structure
shorter than skeletal muscle. Central nuclei, 1-2 per cell. striated cytoplasm. Branched cells connected to each other by intercalated discs
