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CELLULAR BASIS OF MEDICINE > TISSUES AND CELLS > Flashcards

TISSUES AND CELLS Flashcards

1
Q

WHAT ARE TISSUES?

A

-a group of cells with a common structure and function

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2
Q

WHAT ARE THE FUNCTIONS OF EPITHELIUM?

A

-skin protects us from the outside world
-lines our internal organs
-secretion and absorption of molecules; hormones
-detecting and regulating sensations
-separates tissues and organs within the body

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3
Q

WHAT ARE THE CHARACTERISTICS OF EPITHELIUM?

A

-closely attached to each other to form a protective barrier (lateral side forms cell junctions)
-always has one free (apical) surface open to outside the body or inside (cavity) an internal organ
-always had one fixed (basal membrane = molecules of ECM) section attached to underlying connective tissue which faces internal organs
-polarized cell
-avascular = no blood vessels (connective skin below can soak up blood)
-very good self-regeneration due to high activity of stem cells
-many nerves
-minimal extracellular matrix so high amounts of cells

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4
Q

WHAT ARE THE DIFFERENT TYPES OF EPITHELIUM?

A

STRATIFIED ONLY BASAL LAYER SITS ON BASEMENT MEMBRANE
SIMPLE TOUCHES BASEMENT MEMBRANE

SIMPLE SQUAMOUS (single flat layer) = alveoli, blood vessels, glomerulus

SIMPLE CUBOIDAL (single cubed layer, large spherical central nuclei - reabsorption and secretion) = kidney tubules / thyroid follicles / ovarian surface

SIMPLE COLUMNAR (single columns, large oval basally located nucleus) = ciliated tissues like bronchi, stomach, small and large intestine, gall bladder, uterine tube (kinocilia)

PSEUDOSTRATIFIED COLUMNAR (thick/thin single layered columns) = ciliated tissues in the upper respiratory tract, epididymis and vas deferens (stereocilia)

STRATIFIED COLUMNAR (multiple columned layers)= male urethra, conjunctiva

STRATIFIED SQUAMOUS (multiple flat layers, desosomes, central nuclei flattening towards surface)= mouth, vagina, cornea, anal canal, esophagus (KERATINIZED = SKIN)
(NON-KERATINIZED = OESOPHAGUS, ORAL CAIVITY, UPPER LINING OF DIGESTIVE TRACT, RECTUM, VAGINA)

STRATIFIED CUBOIDAL (multiple cubed layers)= sweat, mammary, salivary glands

TRANSITIONAL (glycosaminoglycan layer on surface as an osmotic barrier, basal and surface cells, intermediate layer) = lining of the bladder and urethras

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5
Q

WHAT IS CONNECTIVE TISSUE AND ITS FUNCTIONS?

A

-tissue that binds organs and body parts together
-internal support for organs
-tendon and ligaments protects joints and attached muscles to bone and each other
-stores nutrients
-runs through organ capsules and in deep layers of skin giving strength

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6
Q

WHAT ARE THE CHARACTERISTICS OF CONNECTIVE TISSUE?

A

-surrounded by high amount of extracellular matrix
-bone, cartilage, proper connective tissue
-consists of 3 fibers: reticular, loose, collagen

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7
Q

WHAT IS LOOSE CONNECTIVE TISSUE?

A

AREOLAR: cushion around organs, loose arrangement of cells and fibers
ADIPOSE: stores nutrients, packed with cells and blood vessels
RETICULAR: internal support for organs, delicate network of fibers and cells

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8
Q

WHAT IS DENSE CONNECTIVE TISSUE?

A

REGULAR: regularly arranged bundles packed with fibers running same way for strength in one direction (TENDONDS AND LIGAMENTS)
IRREGULAR: irregularly arranged bundles packed with fibers for strength in all directions (SKIN AND ORGAN CAPSULES)

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9
Q

WHAT ARE SPECIALIZED CONNECTIVE TISSUES?

A

BLOOD: transports materials within blood vessels, immune response
BONE: provides framework and strength for movement, stores calcium, blood producing cells
CARTILAGE: elastic (flexibility while resisting wear = ear), fibro (cushioning and withstanding pressure = vertebral discs), hyaline (shock absorption = embryonic skeleton)

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10
Q

WHAT IS NERVOUS TISSUE?

A

-excitable tissue which transmits signals via neurons to and from body organs
-minimal extracellular matrix and maximum intracellular contact (chemical synapses)
-divided into CNS and PNS
-consists of neurons, glia, nerves, spinal cord and brain

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11
Q

WHAT IS MUSCLE TISSUE?

A

-excitable tissue which allows for contraction
-surrounded by extracellular matrix
-high number of cells

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12
Q

WHAT ARE THE DIFFERENT TYPES OF MUSCLE CELLS?

A

SMOOTH: organ walls and blood vessel walls, involuntary, spindle-shaped cells for pushing things through organs
SKELETAL: large body muscles, voluntary, striated muscle packed in bundles and attached to bones for movement
CARDIAC: heart wall, involuntary, striated muscle with intercalated discs connecting cells for synchronized contractions during heart beat

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13
Q

WHAT IS THE EXTRACELLULAR MATRIX?

A
  • a structural scaffold that directs cell adhesion and migration, as well as regulating cellular growth, metabolism and differentiation signals
    -net between cells in tissues
    -consists of:
    STRUCTURAL PROTEINS: collagen and elastin
    PROTEIN-POLYSACCHARIDE COMPLEXES: proteoglycans (agreccan)
    ADHESIVE GLYCOPROTEINS FOR CELL ADHESION TO MATRIX: fibronectin and laminin
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14
Q

WHAT ARE THE GERM-LAYERS?

A

ECTODERM: skin, pigments, sweat glands, lining of vagina and lining of ends of digestive tract
ENDODERM: lining of respiratory tract, thyroid, pancreas, gallbladder lining, liver
MESODERM: heart, kidneys, RBCs, skeletal and smooth muscle
-formed during gastrulation
(zygote -> blastocyst -> gastrula)

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15
Q

WHAT IS CLEAVAGE?

A

-the series of mitotic cell divisions that produces a blastula from a fertilized ovum. It is the basis of the multicellularity of complex organisms

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16
Q

WHAT IS THE NOTOCHORD?

A

-mesoderm

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17
Q

WHAT IS THE NEURAL TUBE?

A

-ectoderm

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18
Q

WHAT DOES THE NEURAL CREST GIVE RISE TO?

A

-PNS, melanocytes, adrenal medulla

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19
Q

WHAT IS THE FUNCTION OF THE EGG YOLK MEMBRANE?

A

-the first site of RBC formation

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20
Q

WHAT ARE GAP JUNCTIONS?

A

-protein channels linking adjacent cells and through which can pass ions, most sugars, amino acids, nucleotides, vitamins, hormones, and cyclic AMP

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21
Q

WHAT ARE TIGHT JUNCTIONS?

A

-form barriers with external environment

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22
Q

WHAT ARE ADHESION CELL JUNCTIONS?

A

-they mechanically connect cells

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23
Q

WHAT IS PARACRINE CELL SIGNALLING?

A

-type of cellular communication in which a cell produces a signal to induce changes in nearby cells, altering the behaviour of those cells

24
Q

WHAT IS ENDOCRINE SIGNALLING?

A

-form of cell signaling in which the signals are hormones that are released into the blood and act on distant target cells

25
Q

WHAT ALLOWS FOR REGULATED SECRETION?

A

-vesicles - need stimulus / signal
EG: SEROUS CELL OF THE PANCREAS
-epithelia
-pyramidal shape
-big active nucleus
-abundant rough ER
-zymogenous granules (digestive)

26
Q

WHAT ALLOWS FOR CONSTITUTIVE SECRETION?

A

-secretion right after synthesis, no signal, collagen + fibronectin
EG: PLASMA CELL
-connective tissue
-round shape
-big active nucleus
-production of antibodies
-abundant rough ER

27
Q

WHAT IS THE ADPATATION FOR THE SECRETION OF STEROIDS?

A

-produced in cells with smooth ER, round active nucleus, lipid droplets, tubular mitochondria, presence of lipoproteins
EG: LEYDIG CELL
-round oval shape
-abundant in smooth ER
-big active nucleus
-lipid droplets

28
Q

WHAT DO CELLS TRANSPORTING ELECTROLYTES NEED?

A

-sodium-potassium pump
-basal apparatus invagination of the cell membrane
-big active nucleus
-abundant mitochondria
EG: EPITHELIAL CELLS IN DUCTS OF SALIVARY GLANDS AND CELLS IN PROXIMAL AND DISTAL TUBES OF THE NEPHRON

29
Q

WHAT ARE THE CHARACTERISTICS OF THE CELLS FORMING MUCUS?

A

-goblet shape
-rough ER
-well developed Golgi
-mucin vesicles
-flattened nucleus in basal part of cell
EG: GOBLET CELLS IN INTESTINE

30
Q

WHAT IS THE FUNCTION OF A MAST CELL?

A

-contains numerous basophilic granules and releases substances such as heparin and histamine in response to injury or inflammation

31
Q

WHAT IS THE FUNCTION OF A PLASMA CELL?

A

-plasma cells are derived from B lymphocytes and are active in the formation and secretion of antibodies.

32
Q

WHAT IS THE TERMINAL WEB?

A

-filamentous structure found at the apical surface of epithelial cells that possess microvilli. It is composed primarily of actin filaments stabilized by spectrin (INTERMEDIATE FILAMENTS ONLY)

33
Q

WHAT DO MICROFILAMENTS CONSIST OF?

A

-(6nm) actin – myofibrils, cellular cortex, attachment to the adhesive junctions (zonula adherens and focal adhesions) , “purse-string” ring (cytokinesis)- faloidin, cytochalazin

34
Q

WHAT DO INTERMEDIATE FILAMENTS CONSIST OF?

A

-(12nm): cytokeratins, desmin, vimentin, neurofilaments, glial fibrillary acidic protein tissue specificity, used as a marker

35
Q

WHAT DO MICROTUBULES CONSIST OF?

A

-(25nm): subunits α a β tubulin 13 fibrils – 9x2 + 2 – kinocilia, 9x3 centrioles, kolchicin

36
Q

WHAT ARE EPITHELIOCYTES?

A

-epithelial and nerve cells
-maximum of intercellular contacts, with minimal ECM
-Cytokeratins, neurofilaments

37
Q

WHAT ARE MECHANOCYTES?

A

-connective tissues cells (fibroblast, adipocyte), muscle cells
-the cells connected to ECM vimentin, desmin

38
Q

WHAT ARE AMEBOCYTES?

A

-blood cells and immune cells
-free cells without intercellular and EGM contacts

39
Q

WHAT IS PARENCHYME?

A

-Is a tissue (epithelial) producing specific morphological and functional characteristics of a solid organ
-It is enclosed, divided, and sustained by a fibrous connective tissue – stroma
-Stroma brings blood vessels, lymphatics, and nerve fibres to the parenchyme

40
Q

WHAT ARE THE SPECIALIZATIONS OF THE APICAL UPPER PART OF AN EPITHELIAL CELL?

A

apical surface is in direct contact with the external environment
-microvilli are 20-30 irregularly arranged actin filaments which help to increase the surface area and brush border for reabsorption
-stereocilia are long non motile microvilli that increase surface area, many actin filaments, act as vibration sensors in the organ of Corti in the ear, or in act as resorptive cells in the ducts of epididymis
-flagella projections of the cell which can actively move in one direction, powered by dynein, made up of 9 doublets + 2 microtubules, attached to the basal body / kinetosome for support (triplets of microtubules)
-kinocilia are non motile they lack dynein, present on hair-cells and have a central pair of microtubules
-primary cilia are single, non motile cells, 9+0 axoneme, no motor protein, function as sensory receptors
-nodal cilia play a role in the development of the embryo, determining the orientation of the organs

41
Q

WHAT IS KARTAGENERS SYNDROME?

A

-when dynein does not work in the motile projections of the epithelial cells

42
Q

WHAT ARE THE SPECIALIZATIONS OF THE LATERAL / SIDE SURFACES OF EPITHELIAL CELLS?

A

lateral connects cell to cell
-Zonula Occludens (tight junction) which lock cells tight together, right under the apical surface, transmembrane proteins - claudins and occludins connected to actin filaments = blood-brain barrier, digestive system, lungs
-Zonula Adherens (adherent junction) which give high mechanical resistance to tight junctions, cadherin + adaptor plaque proteins (viniculin) attached to actin filaments = endothelium
-Macula Adherens (desmosomes) which are spot intercellular junctions that provide strong adhesion between cells, cadherin + adaptor plaque proteins (desmoplakin) connected to intermediate filaments = skin, intestines, cardiac muscle
-Nexus (gap junctions) function as a fast exchange of substances / signals between neighboring cells, nexus is a small transmembrane channel which directly connects cytoplasms and allows for free diffusion of small molecules, 6 transmembrane connexin proteins make 1 connexon channel.
-Hemidesmosom (anchoring junction) anchors cell-cell lamina, transmembrane integrin and adaptor proteins plektin attached to intermediate filaments

43
Q

WHAT IS INTRACELLUALR COHESION?

A

-mediated by cell adhesion molecules such as CAM - a family of proteins which ensures connection between cells and ECM.
INTEGRINS: connect cells to ECM, play a role in signaling pathways from the ECM
CADHERINS: calcium dependent transmembrane proteins, intracellular part bound to actin and myosin filaments of the cytoskeleton while the extracellular part occupies extracellular space

44
Q

WHAT ARE THE SPECIALIZATIONS OF THE BASAL / LOWER PART OF EPITHELIAL CELLS?

A

basal layer connects with connective tissue, they attach the cell to the ECM
-Basal Membrane works as the mechanical anchorage of epithelium cells, made up of the lamina basalis and lamina fibroreticularis

-Lamina fibroreticularis is composed of collagen III, collagen VII, fibrillin, it makes a connection between the lamina basilis and surrounding connective tissue (product of connective tissue)

-Lamina basilis (product of epithelia cells) is 100-200nm thin so is only visible under the microscope
-lamina rara: thin and not electron dense – appears as a white line under electron microscope, sits on the surface of epithelial cells, integrin basal membrane receptors for laminin and fibronectin (nets made by collagen IV), attached to cell by hemi desmosomes and anchoring fibrils
-lamina densa: thick and electron dense – under electron microscope appears as a thick belt, connected to lamina fibroreticularis by anchoring fibrils, composed of mainly laminin, collagen IV, proteoglycans and glycoproteins.

45
Q

WHAT ARE THE CONNECTIONS BETWEEN THE CELL AND BASAL LAMINAS?

A
  • syndecan – transmembrane protein, actin filaments from within the cell attach to it
  • focal adhesion - integrin bound to actin filament + laminin
  • hemi desmosomes - integrin bound to intermediate filament + laminin
46
Q

WHAT IS THE BASOLATERAL LABYRINTH?

A

-it functions in increasing the surface area for the transport and absorption of nutrients
-found in cells transporting ions and water (proximal and distal tubules of kidneys)
- a lot of Na/K-ATPases found in the membrane and a lot of mitochondria, as nutrients require the aid of protein transporters and energy

47
Q

WHAT ARE MYOEPITHELIAL CELLS?

A

-myoepithelial cells are contractile cells associated with the secretory end-pieces.
-sit on basement membrane
-found in sweat, salivary, mammary, tracheobronchial glands
-form desmosomes and hemidesmosomes with cadherin-mediated cell junctions
-contain large amounts of microfilaments and contractile proteins (myosin, actin, cytokeratins)

48
Q

WHAT IS KERATINIZED EPITHELIUM?

A

-stratified squamous epithelium found in skin, epidermis of the palm of the hand and sole of the foot and the masticatory mucosa.
-forms an effective barrier.
-the surface layer of it consists of dead cells. Keratin is deposited on the surface. T
-the protoplasm of surface cells is replaced by keratin proteins.
-keratinized epithelium is dry and impervious to water.
-provides better protection against abrasions
-consists of dead cells
-no nuclei

49
Q

WHAT IS NON KERATINIZED EPITHELIUM?

A

-Nonkeratinized epithelium is a stratified squamous epithelium found in lips, buccal mucosa, alveolar mucosa, soft palate, the underside of the tongue, and floor of the mouth. -nonkeratinized epithelium is moist, and it contains living cells in the surface layer.
-pervious to water, keratin absent, less protection
-consists of living cells

50
Q

WHAT ARE UMBRELLA CELLS?

A

-Umbrella cells are big, superficial cells within the transitional epithelium
-thicker outer portion of plasma membrane due to plaque proteins - uroplakin

51
Q

WHAT ARE SUPERFICIAL CELLS?

A

-Superficial cells are the largest cells seen on a vaginal smear. The are polygonal in shape and distinctly flat, sometimes having the appearance of being rolled up

52
Q

WHAT ARE CELL INCLUSIONS?

A

-the residual elements of the cytoplasm that are metabolic products of the cell, for example, pigment granules, starches, alkaloids or crystals

53
Q

WHAT ARE THE NAMES OF THE CELLS IN RESPIRATORY EPITHELIUM WHICH ALLOW FOR GAS EXCHANGE?

A

-pneumocyte I and pneumocyte II

54
Q

WHAT IS BRUSH BORDER?

A

-densely packed microvilli cells in the intestine epithelium or proximal tube of the kidney

55
Q

WHAT IS THE DIFFERENCE BETWEEN LAMINS AND LAMININS?

A

lamin = nuclear envelope proteins
laminin = extracellular proteins

CELLULAR BASIS OF MEDICINE (32 decks)

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