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Flashcards in Histology Week 1 Deck (47):

Describe a cell:

The smallest unit of living structure capable of independent existence, composed of a membrane enclosed mass of protoplasm and containing a nucleus. Highly variable and specialized in structure and function, though all must at some stage replicate proteins and nucleic acids, utilize energy and reproduce themselves.


Describe an organelle:

One of the specialized parts of a cell; these subcellular units include mitochondria, the Golgi apparatus, nucleus and centrioles, smooth and rough endoplasmic reticulum, vacuoles, lysosomes, plasma membrane, and certain fibrils


Which organelles have single membrane: intracellular compartments:

- lysosome - perosisome - rER (rough surface - golgi appartus


What structures are bound by two membranes within the cell?

- nucleus - mitochondria


Which organelles are not bounded by membranes:

- nucleolus - actin filaments - centrosome - microtuble - free ribosomes


H&E stain: Hematoxylin and eosin; describe pink vs blue color stain:

Proteins: pink Basophilic dye: negatively charged (blue/purple) - DNA/RNA/ribosomes


What does a pale staining nucleus indicate? What does a dark staining nucleus indicate?

loose packed (euchromatin) more active tightly packed (heterochromatin) less activity


Difference between EM and LM?

EM all in black and white and more detailed; LM in color


Sketch a typical eukaryotic cell.

see pic


Describe Plasma membrane:

acts as a physical barrier to enclose cell contents; regulates material movement into and out of the cell; establishes and maintains an electrical charge difference across the plasma membrane; functions in cell communication • made of phospholipids, cholesterol and proteins • is a lipid bilayer • contains proteins (receptors, pumps, channels) • is not homogeneous in composition



short numerous membrane extensions supported by microtubules, which occur on exposed membrane surfaces of some cells. Move substances



Numerous thin membrane folds projecting from the free cell surfaces support by microfilaments. Increases membrane surface area for greater absorption



large enclosed structure with double membrane, contains chromatins, nucleolus and nucleoplasm. Houses DNA that serves as the genetic material for directing protein synth.



functions in synthesis of ribosomes (initial ribosomal assembly) rRNA


Nuclear pores:

opening through the nuclear envelope. portal for substances to enter and leave



structures essential for protein synthesis, composed of RNA and ribosomal proteins. Exit nucleus through nuclear pore. Macromolecular structure and can only be resolved by EM. 50% RNA by mass



a system of hollow tubules/filaments and their associated proteins (microfilaments, intermediate filaments, microtubles). Filaments self assemble. Responsible for the cell shape and forms mechanical linkages, movement



actin (protein) filament, found throughout the cytoplasm but concentrated just beneath the plasma membrane in the apical projections named microvilli. Also found in the contractile apparatus of muscle


Intermediate filaments:

smaller than microtuble and larger than a microfilament. Made of proteins such as keratins, lamin, GFP. Have different chemical structure and roles in cell func.



made of tubulin and numerous accessory proteins. Important for intracellular trafficking of organelles and vesicles. Flagella and cilia contain a microtuble core that is required for mobility.


Rough Endoplasmic Reticulum (rough ER):

network of membranes with ribosomes, synthesizes proteins for secretion AND integral membrane proteins of the plasma membrane


Smooth Endoplasmic reticulum (smooth ER):

found in cytoplasm, does not contain ribosomes. Synthesizes steroid hormones, detoxifies drugs, synthesizes lipids, glycogen synth and breakdown and storage, calcium storage (muscle contraction)


Golgi apparatus:

modifies, packages and sorts materials that arrive from the ER in transport vesicles; forms secretory vesicles and lysomes



major digestive organelles of the cell, single membrane, hydrolytic enzymes to digest components, best identified by histochemical reaction for acid phosphate Lysome storage disease: Tay-sachs, B-hexosaminidase deficiency, primary lysomal hydrolase defect


What are the four basic tissue types?

Epithelial, connective, neural and muscle


Describe epithelial tissue:

• line cavities and cover surfaces • function is to separate 2 distinct domains while interacting with the contents of each domain. Simple: Squamous (flat), Cuboidal (cube), Columnar (taller>wide), Pseudostratified Stratified (named from what touches the lumen): Squamous, Cuboidal, Columnar, Transitional


Describe muscle tissue:

• specialized for contraction and the production of force. Types: Striated Muscle: Skeletal and cardiac (centrally located nuclei) Smooth muscle: surrounds hollow organs (single nuclei located in the center of the cell)


Describe connective tissue:

• composed of cells and extra-cellular matrix • a function is to support and hold things together It can have more cells than fibers. Connective tissue proper: Loose connective tissue & Dense connective tissue (Regular and Irregular (fibers go everywhere) Specialized Connective Tissue: 1. Blood 2. Hematopoietic tissue 3. Lymphatic tissue 4. Cartilage – Module 2 5. Bone – Module 2 6. Adipose tissue – Module 2


Describe neural tissue:

• made of neurons and glial cells (supporting cells) • function to sense information • specialized to send signals over long distances at high speed Central Nervous System (CNS): Consists of the brain and spinal cord Peripheral Nervous System (PNS): Consists of cranial, spinal, and peripheral nerves. Collections of nerve cell bodies outside of the CNS (ganglia). Specialized nerve endings (motor and sensory)


Define epithelial tissue and differentiate it from the other three basic tissue types

Epithelial tissue: lines cavities and covers surfaces. Its function is to separate 2 distinct domains while interacting with the contents of each domain. (look for large lumen or surface) * tightly packed (contains contents) * Form a sheet * DO NOT contain blood vessels (avascular) * attached to a basement membrane * sit on underlying connective tissue * have polarity (apical interacts with the lumen = drives process, basal interacts with basement and lateral portions)


Identify the “faces” of an epithelial cell and list the membrane modifications that may exist on each face.

Apical: - microvilli (increases surface area, has actin filaments and connect into a terminal web connecting it to the cell), brush border - cillia: shorter, with microtubules, motile (present in respiratory tract), anchored by a basal body, wispy appearance Lateral Surface: cell-cell attachment sites, junctional complexes - occluding junctions: (zonula occludens, seals cells together - anchoring junctions: zonula: goes around the entire cell macula (spot weld) - communicating junctions (gap junctions) Basal Surface - Basement membrane a.) basal lamina: type IV collagen -- scaffolding, laminins - cell ECM interactions, proteoglycans - most of the volume, negative b.) reticular lamina: type III collagen c.) function: attachment to underlying tissue, compartmentalization (cancer), filtration, scaffolding for reconstruction - anchoring junctions: hemidesmosome and focal adhesions - basal infoldings: (nucleus will be more apical) allow for increased transport with more mitochondria to supply the energy


Occluding junction

tight junctions: seal plasma membrane of adjacent cells together. Formed by transmembrane proteins (ie occludin and claudin). Barrier against paracellular transport. Permeability varies. Lateral domain (goes around the entire cell) - tight junction especially important in the kidney to maintain the concentration being excreted



motile structures that can move substances across the epithelial surfaces. It has a core of microtubules. The basal body acts as the organizing center for the cilium



increases surface area of the cell, contain core of actin filaments


Anchoring junctions: zonula adherens and Macula Adherens Desmosome:

zonula adherens: Provides lateral adhesion between adjacent cells, consists of proteins cell adhesion molecules (CAMS) which link into the cytoskeleton Macula Adherens

cadherins from adjacent cells use a calcium-dependent mechanism to span wider intercellular spaces than can the zona occludens. MNEMONIC CADHErins are Calcium-dependent ADHEsion proteins.


Desmosome: strong spotlike junctions between epithelial cells, has an attachment plaque



What's an easy way to remember the order of the cell junctions

ZO, ZA, MA: zona ocluding, zona adherens, macula adherens)


Gap junctions:

permits direct passage of molecules from one to another through pores. coordinates activity of adjacents cells, is an accumulation of transmembrane pores and is formed by subunits of connexin protein family. Opens and closes via a conformational change


Describe simple epithelia and the various types

Simple epithelia: single layer Simple squamous: cells are flat, like scales (width greater than height Has specific names given location: Endothelium simple squamous epithelium that lines blood and lymph vessels (endo = within) Mesothelium: lines walls and covers the contents of closed cavities of the body (meso = middle) Simple cubodial: cells are like cubes (round nucleus) Simple columnar: cells are taller than they are wide (oval nucleus) Pseudostratified: all cells touch basement membrane but NOT ALL reach the apical surface (respiratory system!)


Describe stratified epithelia and the various types

Stratified epithelia: >1 layers (these are classified by the top layer of the cells!) Stratified squamous epithelium: either keratinized (nuclei are visible in apical layer or non-keratinized Stratified cuboidal (sweat glands!) Stratified columnar Transitional epithelium: a stratified epithelium with “dome cells” (can flatten out when the bladder is full) **Columnar (a lot of the gut); Transitional: predominantly lines the urine tract **


What is the function of simple squamous?

frictionless movement of fluids and/or organs, thin barriers for exchange


What is the function of simple cubodial?

May just line a conduit but can absorb and/or secrete materials (great example is a sweat gland)


What is the function of simple columnar?

absorption and/or secretion


What is the function of kerantinized stratified squamous?

protection of dry areas


What is the function of non-kerantinized stratified squamous?

protection of moist areas


What is the function of stratified columnar?

barrier, conduit


What is the function of pseudostratified?

secretion, conduit in resp tract; movemucus, absorption, conduit in epididymis


What is the function of transitional?

A barrier in chamber and tubes that distend

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