Human Organ Systems Test 1, Lectures 1-3

• Protection
• Absorption
• Secretion/excretion
• Sensation
• Contractility

• Specialized extracellular matrix which anchors cells to underlying connective tissue
• Synthesized by epithelia
• Has two layers

• Lamina densa, which contains fine fibrils
• Lamina lucida, which is the electron lucent layer next to the basal cell surface and the lamina densa

• Structure and organization (attachment of epithelium to connective tissue and organization of the basal membrane)
• Filtering (acts as a barrier regulating exchange between epithelium and connective tissue)
• Regulation (binds growth factors that regulat cell proliferation, differentiation, and metabolism)
• Migration (orients movement of epithelial cells)

• Type IV Collagen
• Laminins
• Entactin (nidogen)
• Perlecan

Goodpasture's syndrome, in which patients synthesize antibodies that bind to type IV collagen, resulting in progressive renal failure and pulmonary hemorrhage

Cell nucleus, which parallels the shape of the cell

False. They penetrate the supportive, underlying connective tissue

The connective tissue which lies beneath epithelial cells and the basal lamina. Blood vessels penetrate this tissue.

Trimeric molecules with rodlike and globular domains that form a 2D network, making up most of the basal lamina

Multiadhesive proteins that form a fibrous 2D network with type IV collagen, providing attachment sites for epithelial cells

A rodlike molecule that crosslinks type IV collagen and laminin and helps incorporate other components into the basal lamina

A large, multidomain heparan sulfate proteoglycan that binds to and crosslinks many components of the basal lamina and cell surface proteins

• Two basal laminae attached to one another as seen in the kidney glomeruli or
• The basal lamina of the epithelial cells attached to the reticular lamina of connective tissue cells
• It is not synonymous with basal lamina, as it is thicker

Type VII collagen fibrils embedded in a heparan sulfate gel that anchor the basal lamina to the underlying connective tissue

Hemidesmosomes

• Integrins, such as alpha-6-beta-4
• They link the basal lamina outside the cell to the keratin-based intermediate filament cytoskeleton inside the cell

• Zonulae adherens
• Desmosomes

Zonulae occludentes (aka tight junctions)

Gap junctions (aka intercytoplasmic junctions)

Zonula means belt-like and macula means spot-like

• Aka tight junctions
• Found at the most apical portion of the lateral surface of epithelial cells
• Prevents macromolecules and some water/ions from diffusing across sheets of epithelial cells

• Caused by vibrio cholerae (and other enteric bacteria)
• Toxins produced by these bacteria alter the tight junction permeability barrier of intestinal epithelia by changing the composition or activity of tight junctions
• Massive loss of ions and water into the GI tract occurs, leading to diarrhea and potentially lethal dehydration

• Aka adherens junctions
• Located near the apical surface, just below tight junctions
• Associated with actin/myosin belt that functions as a tension cable to control cell shape
• Actin filaments arise from a terminal web, a meshwork of actin, intermediate filaments and spectin in the apical region of the cell
• Provides the primary adhesive junctions between adjacent cells in an epithelium by linking actin filaments between adjacent cells
• Uses cell adhesion molecules (CAMs) and cadherins (E-cadherins)

• Aka desmosomes
• Button-like points of attachment between adjacent epithelial cells via attachment plaques
• Attach internal to the cell via tonofilaments, which are intermediate filaments composed of cytokeratins that insert into attachment plaques or make hairpin turns and return to the cytoplasm
• Provide tight adhesion between adjacent epithelial cells by linking tonofilaments from cell to cell

• An autoimmune disorger in which patients synthesize antibodies that bind to desmosomal cadherins and disrupt desmosomes and cell-cell adhesion
• Results in blistering skin

• Aka gap junctions
• Present in epithelia but also abundant in nearly all tissues except for skeletal muscle
• Allows communication between cells by permitting passage of small molecules and ions
• Made up of connexons, which are hydrophilic channels made up of connexin proteins

• Fx: Increase cell surface area for absorption
• Actin microbilaments are in the center of each microvillus and are anchored in the terminal web
• The outer surface has a thick coat of glycoproteins, called the glycocalyx (appears as a "brush or striated border")

• Fx: Increase cell surface area for absorption (as in the epididymis) or sense fluid motion or fluid pressure (as in the inner ear hair cells)
• Like long, branched microvilli

• Fx: Movement (flagella) and removal of foreign particles, bacteria and mucus from the lungs or exterior of nose (cilia)
• Made of microtubules in a 9 + 2 arrangement that insert into basal bodies

• Electron-dense structures at the apical pole of epithelial cells
• Allow for attachment of microtubules
• Structurally analogous to centrioles

• Elongated structures that do not move on their own but can bend upon external pressures (such as fluid flow)
• Nearly all differentiated cells of adult tissues, including most epithelial cells, fibroblasts, chondrocytes, osteocytes, smooth muscle cells, skeletal and cardiac muscle, photoreceptor cells, hippocampal neurons, etc. have a primary cilium
• Made of microtubules in a 9 + 0 arrangement and insert into basal bodies

• Polycystis are disrupted in polycystic kidney disease and result in inability to sense fluid flow
• These polycystins form a fluid-sensing mechanism that control the diameter of renal tubules

• Simple
• Stratified
• Pseudostratified (all cells contact the basal lamina, but not all cells reach the free surface)

• Squamous
• Cuboidal
• Columnar
• (These classifications are determined by the most superficial layer)

• Distribution: Inner surface of tympanic membrane, part of nephrons (Bowman's capsule and loop of Henle), lungs, testes, the smallest excretory ducts of many glands, mesothelium lining serous cavities, mesenchymal epithelium lining cavities in connective tissue, and endothelium lining the walls of blood and lymph vessels
• Fx: Exchange, barrier, lubrication

• Distribution: Small ducts of exocrine glands, choroid plexus (in ventricles of brain which secrete or absorb CSF), free surface of the ovary, thyroid follicles, inner surface of the lens capsule, retinal pigment epithelium, and kidney tubules
• Fx: Absorption, conduit (channel), barrier, secretion

• Distribution: Digestive tract, excretory ducts of glands, gallbladder
• Ciliated simple columnar epithelium: Uterus and oviducts, small bronchi of the lung, paranasal sinuses, central canal of spinal cord
• Fx: Absorption and secretion
• Side note--often found with goblet cells, which secrete fluids and are unciliated

• Non-keratinized stratified squamous epithelium: Moist surfaces, lining wet cavities (mouth, vagina, female urethra, anus, esophagus, part of epiglottis, part of conjuctiva adn conrea in the eye)
• Keratinized stratified squamous epithelium: Skin and hard palate
• Fx: Barrier, protection

• Rare
• Distribution: Excretory ducts of sweat glands, developing ovarian follicles, anorectal junction
• Fx: Barrier, conduit

• Relatively rare
• Distribution: Fornix of conjunctiva, cavernous part of urethra, anal mucous membrane, pharynx, epiglottis, large excretory ducts of some glands
• Ciliated stratified columnar epithelium: Nasal surface of the soft palate, larynx, fetal esophagus
• Fx: Barrier, conduit

• Distribution: Large excretory ducts of the parotid and other glands, male urethra
• Ciliated pseudostratified columnar epithelium: Greater part of mucous membrane of respiratory passages (trachea, bronchi, nasal cavity), pharyngoauditory tube, part of typmanic cavity, lacrimal sac, and excretory passages of the male reproductive system
• Fx: Secretion, absorption, conduit

• Definition: Epithelial cells that vary in appearance because they are subject to great mechanical changes due to contraction and distention
• Distribution: Urinary bladder, ureters, and upper part of urethra
• Fx: Barrier, distensible property

• A reversible event where one differentiated cell type is replaced with another mature differentiated cell type
• Usually an adaptation to cellular stress (NOT cancer)
• Examples: Barrett's esophagus, airway epithelial metaplasia (replacement of ciliated pseudostratified columnar cells with stratified squamous cells in response to cigarette smoke), and cervical erosion (non-keratinized stratified squamous epithelium is replaced by glandular columnar epithelium, caused by trauma, infections, and chemicals)

• Unicellular (only goblet cells)
• Multicellular

Unicellular glands (aka mucous cell) that secrete mucin, a protein-polysaccharide that forms a lubricating solution

• Exocrine glands: Secrete into ductal system, retain connections with surface epithelium from which they were derived, discharge product at an external or internal surface
• Endocrine glands: Secrete into vascular system, do not retain connections with surface epithelium of origin, do not have ducts

• Serous: Parotid gland and pancreas
• Mucous: Goblet cells and mucous salivary gland
• Mixed: Submandibular and sublingual salivary glands

Spherical structures that adjacent serous cells form within serous glands

Contain digestive enzymes and are found in serous cells; separate from secretory granules

• Merocrine
• Apocrine
• Holocrine

• Secretory granule fuses with plasma membrane by exocytosis without accompanying loss of cytoplasm
• Salivary glands and pancreas

• Secretory granule plus apical cytoplasm is lost
• Mammary glands and sweat glands

• Entire cell becomes secretory product and is shed
• Uncommon
• Sebaceous gland (cells that produce sebum which are found on skin and near hair follicles)

• Duct system: Simple (one) or compound (branching)
• Secretory units: Tubular, coiled tubular, branched tubular, acinar, branched acinar, tubuluacinar
• *You will need to learn these from the notes*

A tumor of epithelial cell origin

A tumor derived from glandular epithelial tissue

Extracellular matrix

Protein fibers and ground substance

Types I, II, and III

Types IX, XII, and XIV

Type VII

Type IV collagen in basal laminae

• Fx: Resistance to tension
• Densely-packed thick fibers and bundles with variable diameters
• Most abundant form, found in dense and loose CT, skin, tendons, fibrous cartilage, organ capsules, bones, cornea, dentin
• Made by fibroblasts and specialized CT cells such as osteoblasts, odontoblasts, and chondroblasts

• Fx: Resistance to intermittent pressure
• Usually found with many fibril-associated proteins and lots of ground substance, giving it a shock-absorbing property
• Does not form thick fibers--only very thin fibrils
• Found in hyaline and elastic carilages and vitreous body (intervertebral discs)
• Made by chondroblasts

• Fx: Structural maintenance in expansible organs
• Forms reticular fibers, which are loosely-packed thin fibrils with uniform diameters
• Found in smooth muscle, arteries, uterus and in networkds around cells in spleen, lymph nodes, bone marrow, liver, kidney, and endocrine glands
• Made by fibroblasts, smooth muscle cells, reticular cells, Schwann cells, and hepatocytes

• Type I: Strongly birefringent (transmits light unequally in different directions) yellow or red fibers, nonargyrophilic (not capable of binding silver salts)
• Type II: Visible only with picro-Sirius stain and polarization microscopy
• Type III: Weakly birefringent greenish fibers, argyrophilic (does bind silver salts because more sugars are associated with these loosely-packed reticular fibers)
• Under EM: Fibrils have a striabed appearance due to lacunae and overlapping regions

Anchors skin epidermal basal lamina to connective tissue

Deficiency of type III collagen (reticular fibers) characterized by ruptures in arteries (often aorta) and intestines

Defects in processing type I collagen and causes hyperextensible skin but increases chance of eyeball rupture

Patients have double-jointedness

• Pro-a-chains are made first
• Procollagen is assembled in the ER
• Proline and lysine residues are hydroxylated in the ER
• Procollagen is packaged into secretory vesicles in the Golgi and secreted
• Procollagen peptidases cleave procollagen into insoluble tropocollagen, which polymerizes in an overlapping pattern to form collagen fibrils

• Caused by a deficiency of vitamin C, which is a cofactor for the hydroxylation of proline and lysine residues
• Bone growth, wound and fracture healing, and stability of adult organs may be affected, in addition to periodontal bleeding and ulceration

• Found in almost all connective tissue, but is enriched in places that must stretch and relax (skin, tendons, heart, blood vessels, fascia of anterior abdominal wall)
• Made by fibroblasts and smooth muscle cells

• Microfibrils: Elastic scaffold consisting of fibrillin and associated glycoproteins
• Elastin: A non-glycosylated protein that forms amorphous deposits

• 1) Oxytalan fibers: Lattice of fibrillin without elastin
• 2) Elaunin fibers: Elastin protein is deposited and surrounds oxytalan fibers
• 3) Elastic fibers: Blob of elastin surrounded by tubular microfibrils

• Mutations in the fibrillin gene result in defective elastic fibers
• Tissues rich in elastic fibers (such as large arteries) suffer a lack of resistance and patients often suffer ruptures in the aorta

Glycosaminoglycans (GAGs) and glycoproteins

• Linear (non-branching) polysaccharides
• All GAGs are in proteoglycans except for hyaluronic acid

Made up of glycosaminoglycans and a protein core

A GAG associated with type I collagen; found in the dermis, tendons, ligaments, and fibrocartilage

A GAG associated with type II collagen; found in hyaline and elastic cartilage

A GAG associated with types III and IV collagens; found in reticular fibers and basal laminae

A GAG found in cartilage

• Structural: Bind together protein fibers of ECM and anchor cells to ECM
• Hydration: Bind lots of cations (usually sodium) and water

• Protein-sugar macromolecules composed primarily of proteins (whereas proteoglycans are primarily carbohydrate)
• Examples: Fibronectin (cell adhesion and migration), chondronectin (holds chondrocytes to collagen), and laminin (binds epithelia to basal lamina)

• Are generated in the connective tissue and produce the ground substance of the tissue
• Includes primitive mesenchymal cells, fibroblasts and fibrocytes, and adipose cells

• Cells that migrate into connective tissue. Their main functions are immunological and defense (phagocytosis, cytokine production, antigen presentation, and allergic reactions)
• Includes mast cells, neutrophils, monocytes, macrophages, lymphocytes, plasma cells, and eosinophils.

• Arise from embryonic mesenchyme (mesoderm) which is plentiful in the fetus. These multipotent undifferentiated CT cells then decrease in numbers until persisting as single cells along small blood vessels in the adult.
• Fx: Produce more indigenous CT cells

• Arise from primitive mesenchymal cells
• Fx: Make and secrete the fibers and ground substance of CT ECM (collagen, elastin, GAGs and PGs, and adhesive glycoproteins)
• Also play a role in wound healing by repairing the area by making protein fibers and ground substance

• Arise from primitive mesenchymal cell
• Fx: Store neutral triglycerides. These triglycerides remain in the cell for an average of 4 days. "Brown" fat cells (multilocular cells) are important for heat production in babies and hibernating animals. Human adults have only unilocular tissue cells.

Excessive fat accumulation in unilocular tissue cells that become abnormally large

Excessive fat accumulation in which adipocyte number increases

• Arise from hematopoietic stem cells in the bone marrow
• Fx: Begin the inflammatory response, which is important for beginning allergic reactions. Also recruits eosinophils. Secretes granules containing heparin (anti-coagulant), histamine (increases permeability of vascular endothelial cells), and proteolytic enzymes, which can cause itching and edema.

• Aka neutrophils
• Arise from bone marrow and respond to chemotactic factors to migrate via bloodstream
• Fx: Rapid defense system, phagocytosis following recognition by complement or IgG. Cells are committed to die after phagocytosis because they are unable to synthesize more granules (lysosomes) or membrane receptors.

• Arise from bone marrow and respond to chemotactic factors to migrate via bloodstream
• Fx: Provide a population of potential macrophages to CT

• Arise from monocytes
• Fx: Defend the body by ingesting and killing bacteria and fungi which have been coated by IgG or serum complement, ingest wastes such as dead cells and foreign particles, and store wastes in residual bodies
• In addition, they can further mature to give rise to specialized macrophages for specific tissues, such as osteoclasts (bone), Langerhans cells (skin), and dendritic cells (lymph nodes)

• Arise from bone marrow or lymphatic nodules in CT. They are motile and migrate through endothelia and epithelia.
• Fx: Immunologic (T cells initiate cell-mediated immune response and B cells divide and produce plasma cells). Both have receptor sites for antigens on the surface membrane

• Arise from B lymphocytes in CT
• Fx: Synthesize and secrete large amounts of a specific immunoglobulin (up to 2000 mol/sec)

• Arise from bone marrow via bloodstream
• Fx: Participate in response to allergies and certain parasitic infections

• Loose
• Dense irregular
• Dense regular

• Many cells and ground substance
• Made up of an irregular arrangement of collagen fibrils and elastic fibers
• Fx: Flexibility
• Found in mesentary, next to epithelium, and around blood vessels and glands

• Few cells and ground substance
• Made up of a non-parallel, rough-lattice arrangement of collagen fibers and a random arrangement of elastic fibers
• Fx: Resist stress
• Found in dermis, organ capsules, periosteum, and perichondrium

• Few cells and ground substance
• Made up of a parallel arrangement of collagen fibers and varying amounts of elastic fibers
• Fx: Resist stress
• Found in tendons and ligamens, and in the cornea of the eye (GAG matrix and no elastin)

Hyaline, elastic, fibrous

• Made up of many type II collagen fibrils in a homogenous mixture
• Fx: Cusion forces, form temporary skeleton
• Found in articulations, the temporary skeleton, ventral ends of ribs, larynx, trachea, and bronchi

• Made up of many type II collagen fibrils and numerous branched elastic fibers
• Many chonbroblasts
• Fx: Flexible skeleton
• Found in the auricle of the ear, the external auditory meatus, the auditory tube, epiglottis, and parts of the larynx

• Made up of type I collagen fibers (resembling dense connective tissue), resulting in a little matrix that is acidophilic (collagen has many + charges)
• Few cells and proteoglycans
• Fx: Stability
• Found in tendon attachments and linings, intervertebral discs, and the pubic symphysis

Made of collagen, proteoglycan aggregates (GAGs that are hydrated gels attached to proteins), and glycoproteins (adhesive proteins that bind cells and ECM such as integrins)

• Free, untrapped cells in the ECM of cartilage that secrete matrix and fibers
• These cells persist int he perichondrium and undergo mitosis

• Cells that are trapped in lacunae of cartilage and are surrounded by matrix
• They bind to the collagen in the ECM via chondronectin
• Have mitotic potential during growth but are limited in adult

An adhesion molecule (glycoprotein) which binds chondrocytes to collagen in the ECM of cartilage

• Interstitial (inside the cartilage tissue) growth occurs only in the young and results in isogenic populations of cells in cell nests
• Appositional growth is from the outside inwards from the chondrogenic layer of perichondrium
• Somatomedin C and other growth factors promote cartilage synthesis

A growth factor made by the liver which stimulate cartilage production

• An outside, fibrous layer (where fibroblasts secrete type I collagen)
• An inside, chondrogenic layer (where appositional growth occurs via chondroblasts)

Typically does not occur due to low metabolic rate. Tissue is avascular and receives nutrients from matrix. Does occur more easily in children

• Annulus fibrosis: Fibrocartilage surronded by external layer of dense connective tissue
• Nucleus pulposis (aka hyaline plate): Gel-like, contains hyaluronic acid and type II collagen

• Dense collagen matrix
• Mineralized matrix
• Repairable
• Remodeling

Found on the surfaces of all bones

Found in the interior of bones. Has a honeycomb appearance, which reduces bone weight while still providing support. Marrow is found within spaces.

A central canal and the concentric osseous lamellae encircling it, occurring in compact bone. Also called the Haversian system, it is necessary for blood, lymph, and nerve supply.

Fibrous outer layer and osteogenic inner layer

The inner lining of bone surfaces made up of osteogenic cells and small amounts of collagen

Stem cells --> Mesenchymal cells --> Osteoprogenitor cells

• Non-mitotic cells that arise from osteoprogenitor cells
• Secrete bone constituents (collagen and matrix)

Non-mitotic cells that are trapped in lacunae which are necessary for survival. They form cell-cell contact via gap junctions

False. Bone is both vascularized and does contain nerves

Canals between adjacent lacunae that contain osteocyte processes

A 1-2um thick matrix with adhesion molecules but no collagen

Connect parallel Haversion canals

• Interstitial: Between osteons
• Concentric: In osteons
• Circumferential lamellae: At outer and inner bone surfaces

Branching connections that are found in spongy bone. They must be about .2mm in order to maintain weight

All immature bone and interiors of mature bones

• Diaphyseal: Supply to the shaft of the long bone from the nutrient artery
• Epiphyseal-metaphyseal: Supply to the ends of long bones which have distinct supply to the epiphysis and metaphysis

Collagen (type I mostly), binding proteins, glycoproteins, and growth factors

Hydroxyapatite needles, amorphous CaPO4, and minerals, which are stored in bone

Give bone its hardness. Are found in needle-like shapes, with an interior surface and a hydration shell, which facilitates ion exchange between the crystals and body fluids

Multinucleated cells derived from the fusion of multiple monocytes which cause bone resorption at the ruffled border

Oteoclasts release hydrolytic enzymes from lysosoes to remove organic matter and H+ to dissolve minerals and activate the enzymes by creating an acidic environment

Dense bone caused by a genetic disease. Osteoclasts do not have ruffled borders and cannot resorb enough bone

Use and disuse of bone are directly related to their internal architecture by opposite effects (ex: bed rest leads to bone loss and activity leads to bone deposition)

• Decreased bone density caused by an imbalance of bone resorption and deposition (age related, diet deficiencies, endocrine, drug related)
• Major sites: Vertebrae, femoral necks, and wrists

• Calcitonin: Inhibits osteoclast resorption
• Estrogens: Decrease rate of bone turnover
• Androgens: Increase bone density
• Growth hormone: Increases bone deposition

• Parathyroid hormone: Cause a calcium shift from the matrix to extracellular fluid (hypercalcemia)
• Thyroxine: Stimulates osteoclast resorption

• Aka growth plate
• The plate of cartilage which separates diaphyseal and epiphyseal bone during growth
• Has zones of inactivity, proliferation, hypertrophy, and calcification

A region of bone on the diaphyseal side of the epiphyseal disk which is characterized by ossification at the edge of the cartilage and by resorption of bone on its interior surfaces towards the diaphysis

• Has more cells than mature bone
• Is non-lamellar, has more heterogeneous ECM, and collagen is disorganized

Lamellar bone in which collagen is oriented in the same plane (but is perpendicular in the next lamella)

Aka the shaft, the primary center of ossification in a long bone