Chapter 3: Compartmentalization - Cells and Tissues Flashcards
separates cell from environment
cell membrane
what are the functions of the cell membrane?
- physical isolation, separates ICF from ECF
- Regulation of exchange with the environment, entry of ions and nutrients, elimination of cellular waste and release of cell products
- Communication between the cell and its environment, contains proteins that allow the cell to respond to external changes
- Structural support, create the cells cytoskeleton, form cellular junctions, and connect to the extracellular matrix. These cell-cell and cell-matrix junctions help to stabilize the structure of tissues
what does the fluid mosaic model entail?
- Phospholipids
- Sphingolipids-phospholipids or glycolipid heads with longer fatty acid tails.
- Cholesterol
- carbohydrates
- integral proteins
- peripheral proteins
help to decrease permeability of the cell to small water-soluble molecules and helps to keep the membrane flexible or fluid with changing temperatures.
cholesterol
- form bilayers, micelles, or liposomes
* arrange themselves so that their nonpolar tails are not in contact with aqueous solutions such as extracellulalr fluid
membrane phospholipids
forms a sheet
phospholipid bilayer
- droplets of phospholipid
* important in lipid digestion
micelles
have an aqueous center
liposomes
embedded within the lipid bilayer, so they can be dissociated from the membrane only by disrupting the bilayer
integral proteins
what are the different types of integral proteins?
- enzymatic proteins
- transmembrane proteins
- lipid-anchored proteins
what are examples of integral proteins with enzymatic function?
- G proteins
2. Receptor molecules
span the lipid bilayer, with surfaces exposed to both the ICF and ECF
transmembrane proteins
what are examples of transmembrane proteins?
- ion channels
2. carrier proteins
can be attached to lipid tails (sphingolipids) that insert into the bilayer (play a role in lipid rafts)
lipid-anchored proteins
- are loosely bound to the membrane by associations with integral membrane proteins or phospholipids.
- attached to cytoskeleton
- some enzymatic function
peripheral proteins
primarily on the extracellular surface of the membrane
carbohydrates
what are the two main functions of carbohydrates in the membrane?
- form the glycocalyx
2. function in cell recognition, labeling the cell as part of the body or as a distinct type of cell
- *a protective layer that also functions in holding cells together
- *formed by carbohydrates
glycocalyx
carbohydrates attached to proteins
glycoproteins
carbohydrates attached to lipids
glycolipids
synthesized and secreted by cells and its composition varies from tissue to tissue
extracellular matrix
what are the 2 basic components of extracellular matrix?
- proteoglycans
2. insoluble protein fibers
provide strength and anchor cells to matrix
insoluble protein fibers
what is a subset of proteoglycans?
glycoproteins
what do insoluble fibers include in the extracellular matrix?
- collagen
- fibronectin
- elastin
- laminin
what are the three major types of cell junctions?
- gap junctions
- tight junctions
- anchoring junctions
- form small channels that enable ions and small molecules to move between two cells
- communicating junctions
gap junctions
membrane proteins composed of smaller proteins called connexins
connexons
what are examples of gap junctions?
smooth muscle
cardiac muscle
- integral membrane proteins called claudins and occludins fuse adjacent cells together to form a nearly impermeable barrier to the movement of substances between cells
- occluding junctions
tight junctions
what does the barrier of tight junctions result in?
causes solutes to cross epithelial cell layer (transepithelial transport), rather than going around (paracellular movement)
what are examples of tight junctions?
epithelial cells that line hollow structures of the kidneys, or gastrointestinal tract
attach cells to each other or to the ECM.
anchoring junctions
what are cell-cell junctions created by?
created by cadherins which connect across the intercellular space
link actin fibers in adjacent cells
adheren junctions
- the strongest
* link intermediate filaments of the cytoskeleton
desmosomes
use integrins which are membrane proteins that can be receptors
cell-matrix junctions (anchoring)
what is used in cell-matrix junctions?
- hemidesmosomes
2. focal adhesions
anchor intermediate fibers of the cytoskeleton to matrix proteins such as laminin
hemidesmosomes
tie intracellular actin fibers to matrix proteins such as fibronectin
focal adhesions
what are the 4 major classes of tissues?
- connective
- neural
- muscle
- epithelial
provides structural support, but also encompasses fluids such as the blood and lymph, which serve to “connect” the various parts of the body together by providing avenues of communication
connective tissue
excitable cells carrying information in the form of electrical and chemical signals
neural tissue
excitable cells with the ability to contract and produce force
muscle tissue
play a role in both protection of the internal environment and regulation of the exchange of materials between the ICF and ECF
epithelial tissue
what is the structure of epithelia?
- one or more layers of cells
- Separated from underlying tissue by the basal lamina or basement membrane (extra cellular layer composed of collagen and laminin in proteoglycans)
How is epithelia structurally divided into two types?
- sheets of cells lining the body surfaces of internal and external surfaces
- secretory epithelia (glands)
what do most epithelia attach to?
basal lamina or basement membrane
how do epithelial cells attach to the basal lamina?
using cell adhesion molecules
acellular matrix layer that is secreted by the epithelial cells
basal lamina
what are the histological classifications of epithelial tissue?
- layering (simple or stratified)
- shape (squamous, cuboidal, columnar)
- function (exchange, transport, ciliated, protective, secretory)
- allows for rapid gas exchange
- simple squamous epithelium (very thin)
- endothelium lines the circulatory system
exchange epithelia
- cuboidal or columnar in shape
- have membrane modifications
- tight junctions force materials to cross the cell
- many mitochondria that provide energy for transport
transporting epithelia
what are the membrane modifications of transporting epithelia?
- apical membrane faces lumen and has microvilli
* basolateral membrane faces ECM and may also have fold
moves fluid and particles in respiratory system and female reproductive tract
ciliated epithelium
- are found in areas of mechanical and chemical stress.
- stratified tissue
- may be strengthened by secretion of keratin
protective epithelia
- scattered among other epithelial tissue
* grouped into glands
secretory epithelium
what are the glands of secretory epithelium?
- exocrine glands
2. endocrine glands
- release products to external environment (mostly through ducts)
- serous secretions
- mucous secretions
exocrine glands
watery (digestive,tears, and sweat)
serous secretions
produced by goblet cells
mucous secretions
release hormones into extracellular compartments (ECF or blood)
endocrine glands
how many layers do exchange epithelium have and what is its cell shape?
one cell layer
flattened shape
has pores between cells that permit east passage of molecules
exchange epithelium
where are exchange epithelium found?
lungs
lining of blood
vessels
how many cell layers do transporting epithelium have and what is the shape?
one layer
columnar or cuboidal
- tight junctions prevent movement between cells
* surface area increased by folding of cell membrane into fingerlike microvili
transporting epithelium
where are transporting epithelium found?
intestine
kidney
some exocrine glands
how many cell layers do ciliated epithelium have and what is the shape?
one cell layer
columnar or cuboidal
one side covered with cilia to move fluid across surface
ciliated epithelium
where are ciliated epithelium found?
nose, trachea, upper airways; female reproductive tract
how many cell layers do protective epithelium have?
many
what is the cell shape of protective epithelium?
flattened in surface layers; polygonal in deeper layers
cells tightly connected by desmosomes
protective epithelium
where are protective epithelium found?
skin and lining of cavities that open to the environment
how many cell layers do secretory epithelium have and what is the shape?
one to many layers
columnar or polygonal
- protein secreting cells filled with membrane bound secretory granules and extensive RER
- steroid secreting cells contain lipid droplets and extensive SER
secretory epithelium
where are secretory epithelium found?
- exocrine glands: pancreas, sweat glands, salivary glands
* endocrine glands: thyroid and gonads
- minimal matrix
- basal lamina matrix
- no direct blood supply
- has microvilli, cilia
- covers body surface, lines cavities and hollow organs and tubes; secretory glands
epithelial tissue
- extensive matrix
- varied matrix
- cartilage has no blood supply
- supports skin and other organs; cartilage, bone, blood
- cells not in layers
connective tissue
- minimal matrix
- external lamina matrix
- can generate electrical signals, force, and movement
- makes up skeletal muscles, hollow organs, and tubes
- cells linked in sheets or elongated bundles
muscle tissue
- minimal matrix
- external lamina matrix
- can generate electrical signals
- throughout the body, but mainly in brain and spinal cord
- cells isolated or networked
nerve tissue
