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Chapter 10B: Cell Architecture II - Coggle Diagram
Chapter 10B: Cell Architecture II
Levels of biological organization
cells --> tissues --> organ --> organ system --> organism
differentiated cells: cells with distinct functions
tissue: group of cells that have a similar structure, which work together to perform a specific function
organ: structure consisting of more than one tissue, which work together to perform a specific function
organ systems: groups of organs that work together to perform a specific function
Multicellularity: enables specialization and collaboration of different cells
examples (form enables function)
red blood cells: concave, can transport O2 and CO2
epithelial cells: high surface area for absorption
neurons
striated muscle cells
Cell specialization: how do they get there?
cells can take on many different forms and functions through differentiation
cell gradually takes on many different posibilities during development
example: hematopoietic stem cell
red blood cell (carries O2)
macrophage (clears bacteria)
plasma cell (secretes antibodies)
Tissues join together to coordinate function
examples
in plants:
epidermis: outer layer
ground tissue: in between
vascular tissue (xylem, phloem): transports water and nutrients
in animals
epithelium
connective tissue (mesenchyme)
muscle
nerves
blood vessels lining
Tissues can form organs: mixture of distinct tissues that are joined together and have a coordinate function
PLANTS
ex. leaves have many shapes and sizes but most are all flat and green
leaves are specialized for photosynthesis
palisade mesophyll - mostly CHLOROPLASTS
spongy mesophyll - gas exchange
stomate - opens/closes for gas and water exchange
vascular tissue (xylem, phloem) - transports water and nutrients
epidermis
wide variation: i.e. tendrils, spines, storage leaves, reproductive leaves, bracts
Extracellular matrix holds plant tissue together
cellulose is the primary component
development
middle lamella
primary cell wall
secondary cell wall (crosslinking of cellulose + lignin) (CLOSEST TO PLASMA MEMBRANE)
Holding it all together: cytoskeleton, cell junctions, extracellular matrix
ANIMALS
STROMA: Connective tissue
composed of ECM, fibroblasts (mobile, secretes components of ECM), and mesenchymal cells)
HOLDING IT ALL TOGETHER: EPITHELIAL CELLS form a sheet
examples
kidney tubule
lining of urinary system
intestines
lungs
Functions in different organs
barrier/protection (skin, stomach epithelium)
nutrient absorption (intestine)
water absorption (kidney)
gas exchange (lungs)
contraction (neural tube)
secretion (pancreatic beta cells)
The most common lethal forms of cancer arise in skin (carcinomas)
METASTASIS: epithelial cells leave sheet and enter body through connective tissue
involves ability of tumor cells to pass basal lamina TWICE
to leave primary tumor
to settle into a place to form metastatic growth
benign tumor: locked in place (no invasion or metastasis)
malignant tumor: cells have invaded surrounding tissue and entered bloodstream or lymph system
lethality comes from invasion and metastasis (ability of cancer cell to move to another part of the body and form a new tumor)
tumor cells breach the basal lamina and move into connective tissue
epithelial cells have orientation (polarity)
outside = apical (pointing outward)
All molecules that are coming in through the body (i.e. gut) pass through the epithelial sheet (there are tight junctions)
apical side and tight junctions keep outside solutes from coming inside the tissue
inside = basal (pointing inward)
composed of special types of collagen and laminin (attached to integrins from epithelial cells) as well as other proteins
Basal lamina: a special kind of ECM found attached to epithelial sheets (right under epithelium)
joined together in a sheet
FEATURES OF EPITHELIAL CELLS
1) Epithelial cells can be attached to:
one another
to ECM (to the basal lamina)
Both CADHERINS and INTEGRINS (transmembrane proteins) attach to cytoskeleton inside the cell
Cadherens attach cells TOGETHER (adheren junctions, desmosomes)
adherens junctions hold cells together (through cadherin dimers that attach ACTIN inside one cell to ACTIN inside a neighbor cell)
Integrins attach to cells TO THE ECM (basal lamina, hemidesmosomes)
Integrins attach cells to the basal lamina
epithelial sheet would COME APART if integrins and basal lamina detach
2) Epithelial sheets (multiple cells) are held together by:
ALWAYS: more flexible attachments:
adherens junctions and attachment to basal lamina
(SOME TYPES, EPIDERMAL CELLS): permanent attachments
desmosomes (between cells) and hemidesmosomes (between cells and basal lamina)
3) Fibers that are localized on inside of each cell are being attached to something
adheren junctions, attachments to basal lamina
attached to actin
desmosomes, hemidesmososmes (avoids tearing, gives structural stability to outer body)
attached to intermediate filaments
