Download 09.13.10 Lecture Cells and Size

Bio/Chem03: 9/9/09-Goutte
Cell = the unit of life
•  size
•  common features
•  specializations
•  environment
Blood
•  roles
•  composition
•  responsiveness
•  self-renewal and balance
•  disease
> > > > > > > 1 m = 103 mm = 106 µm = 109nm poppy seed
The “average cell” (human)
Basic Cell plan:
ATP production
intracellular
digestion
storage of genetic
material (DNA);
site for DNA
replication and
transcription
into RNA
transport compartment
site for nasty reactions
(oxidation) ie breakdown of
products that yield dangerous
hydrogen peroxide
newly made proteins and lipids
are modified and sorted for
transport to other parts of cell
production site for lipids and
proteins that are either secreted
or membrane-bound
Basic Cell plan:
and now...Variations on a Theme...
shape and content vary to allow
cell specialization: examples
cells that specialize in secretion are packed full of secretory granules
extended ER allows cells to mass produce a protein
and ready it for secretion
activated B cell (WBC) in mass-production
mode (making antibodies to be secreted)
some cells have very long extensions
ex. long ultra thin projections of nerve cells allow
sending/receiving chemical signals from/to distant tissues
terminal branches of axon
reach target cells
axon
(<1mm – 1m)
fibroblast
dendrites receive signal
vs.
neuron long extensions =
membrane and
microtubule fibers
(protein)
The cell’s environment
The organization and distribution
of cells within tissues contributes to how a cell functions
rod cell
from retina
The cell’s environment
cells as parts of tissues
duct cells in the kidney
30 µm The “extracellular matrix”
in which cells are embedded
can be simple, or very
complex, involving a network
of protein fibers
Blood considered a “tissue” with cellular and noncellular components;
(special because it is a “liquid tissue”)
Roles:
Distributor
• heat
• cells
• O2, CO2
• nutrients
• proteins
• electrolytes
• waste products
• chemical signals (ex. hormones)
Protector
• against infection
• against injury
Full-Body Delivery System that is far-reaching, fast, and self-repairing
Blood gravity
(or centrifugation)
cells
plasma
plasma is 90% water with dissolved substances
albumin is a sticky carrier protein
(critical for maintaining osmotic pressure of blood)
γ globulins are immunoglobulins
(critical for immune system)
α and β globulins act as carriers
(for substances such as iron, cholesterol, hormones)
fibrinogen is the raw material for building clotts
white blood cells
adaptive immune system:
make specific antibodies
destroy specific target
cells
“cells in
transit”
platelets
innate immune system:
professional phagocytes
eat invaders and debris
involved in
allergic response;
secrete
histamines
in bone marrow
RBC matures from an erythroblast:
nucleus is spit out and ultimately
mitochondria, ribosomes, etc. also
RBC
(erythrocytes)
released into circulation;
final maturation takes one day
capillary diameter = 3-5 µm
RBCs are small and flexible enough to pass
only last ~ 3 months