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!
- cells are about ______% water
- 60%
- cells vary in length
- 2 micrometers to 3 feet
- possible cell shapes
-
disk
threadlike
pointed
cubelike - 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 - nucleoli
- sites where the ribosomes are assembled before they migrate to the cytoplasm
- chromatin
- 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
- microvilli:
- fingerlike projections that increase the surface area of the cell for absorbtion
- tight junctions:
- bind cells to other cells--> hold cells together
- desmosomes
- anchor the cells together-- last resort stick
- gap junctions
- allow communication between cells
- cytoplasm consists of three main elements
- cytosol, organelles, inclusions
- cytosol:
- fluid that suspends other elements
- organelles
- machinery of the cell
- inclusions
- 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
- mitochondria:
- sausage shaped--> provide ATP for cellular energy
- ribosomes:
- 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
- lysosomes
- vescicles: demolition sites that breakdown wastes and recycle-- digestive enzymes
- peroxisomes
- small vesicles: used to disarm dangerous free radicals/chemicals: repicate by pinching in half
- cytoskeleton
- protein strutures along the cytoplasm: determines the cell shape; provides framework
- centrioles
- rod shaped bodies used during cell division: create spindle fibers
- fibroblasts
- protein extentions: net, meshlike material-- connect body parts (star shaped)
- erythrocytes
- 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
- Diffusion:
- the net movement occures from regions of higher concentration to areas of lower concentration
- osmosis:
-
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
- transporters
- 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
- enzyme
- 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