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Anatomy Chapter 3: Cells and Tissues


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cells are made up of primarily four elements:
carbon, hydrogen, oxygen, nitrogen
_________carry out all chemical activities
cells are about ______% water
cells vary in length
2 micrometers to 3 feet
possible cell shapes
3 main regions of the cell
cytoplasm, plasma membrane, nucleus
nucleus: function
control center-- contains instructions for controlling the body
necessary for cell reproduction
nucleus: structure
nuclear envelope, nucleoli, chromatin
nuclear envelope: (nuclear membrane)
--semi-permeable phospholipid bilayer
--nuclear pores
sites where the ribosomes are assembled before they migrate to the cytoplasm
composed of DNA and protein; condense to form chromosomes when the cell divides; runs throughout the cell
plasma membrane:structure
phospholipid bilayer: semi-permeable--> phosphate hydrophilic heads and lipid hydrophobic tails
plasma membrane: function
contains the cell contents and separates them from the surrounding enviornment
function of proteins scattered in plasma membrane
hormone receptors, binding sites, transporting
specializations of the plasma membrane
microvilli, membrane junctions-- tight, desmosomes, gap
membrane junctions
desmosomes, gap, tight
fingerlike projections that increase the surface area of the cell for absorbtion
tight junctions:
bind cells to other cells--> hold cells together
anchor the cells together-- last resort stick
gap junctions
allow communication between cells
cytoplasm consists of three main elements
cytosol, organelles, inclusions
fluid that suspends other elements
machinery of the cell
non-functioning units: wastes, electrolytes--chemical substances that may or may not be needed
cytoplasmic organelles:
mitochondria, ribosomes, endoplasmic reticulum, golgi aparatus, lysosomes, peroxisomes, cytoskeleton, centrioles
sausage shaped--> provide ATP for cellular energy
small, dark bodies-->sites of protein synthesis: make protein--> found in the cytoplasm and the rough e.r
golgi apparatus:
modify and package proteins, produce different kinds of packages: secretory vesicles, cell membrane components, lysosomes
vescicles: demolition sites that breakdown wastes and recycle-- digestive enzymes
small vesicles: used to disarm dangerous free radicals/chemicals: repicate by pinching in half
protein strutures along the cytoplasm: determines the cell shape; provides framework
rod shaped bodies used during cell division: create spindle fibers
protein extentions: net, meshlike material-- connect body parts (star shaped)
no organelles when fully mature: blood cells-- transports oxygen (innertube shaped)
epithelial cells
square, tight junctions
create a protective lining
skeletal muscle cells
involved in large scale movements (rod shaped)
smooth muscle cells
involved in involuntary movement (tongue, uterus, intestines, organs)
fat cell
cell that stores nutrients: large and globular: purpose to store fat
nerve cell
gathers information and controls body functions: must be able to recieve information: crazy shape (long)
sperm cell
reproductive cell (contain tails)
cellular transport
the movement of compounds across the outer wall or cell membrane
cellular transport is critical to functioning
take in and release compounds, reulates the amount of compounds that it needs
_____ are embedded in the plasma membrane
proteins, cholesterol
2 characteristics that prevent a molecule from passing through the cell membrane
size, polarity: polar substances have difficulty passing becuase of the non-polar heads
polar molecules do not pass through the membrane
too large, dont mix well with non-polar molecules
water is able to pass through the plasma membrane although it is polar
small enough to pass through, random vibrations
the net movement occures from regions of higher concentration to areas of lower concentration
water moves from regions of low solute concentration to areas of high solute concentration
aim: to produce more equal solute concentrations
distilled water/ cells
if a cell is submerged, then the cell will swell because of lack of solute and it will eventually burst-- water moves to areas with higher solute concentrations
facilitate the passage of molecules across membranes
three steps involved in passage of a molecule into a cell
bindong, conformational change of the protein, release
difference between passive and active transporters
passive: dont use energy
active: use energy
example of passive transporter
glucose permease
glucose permease
passive transporters move molecules:
from high concentration to low concentration--> absense of glucose permease--> water moves fast, glucose moes fast
diffusion process
water enters the cell with greater concentration, and then both water and solute enter at an equilibrium back to the cell with lesser concentration
Sodium Potassium Pump
present in all cells: especially in nerve cells--- move solute from areas of lower concentration to areas of higher concentration

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