Anatomy & Physiology I Ch. 3 (Cells)

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Cell

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Basic, living structural and functional unit of the body

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Cytology

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the study of cells

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Plasma Membrane

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Outer membrane which seperates the cells internal and external environments

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Cytosol

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The thick semifluid portion of the cytoplasm.
Contains: soluble proteins & enzymes, nutrients, ions, and organelles

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Cytoplasm

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All the cell contents between the plasma membrane and nucleus

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Organelles

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Distinct structures with specific functions

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Inclusions

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Temporary structures that contain secretions and storage products of the cell

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Fluid Mosaic Model

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Plasma membrane is a fluid lipid bilayer with proteins embedded in it. This is the most current model. (Lock and Key" model isn't used anymore but still a decent model)

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Microtubules

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Protein tubulin, 25nm in diameter, causes entire movement of cell

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Function of Glycolipids

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Not completely known; allows adhesions among cells and tissues; mediates cell to cell recignition & communication; helps regulate growth & development

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Ampipathic

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Has polar and non-polar

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Plasmalemma structure

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-Bilayer of lipids embedded w/ proteins
-Lipid bilayer makes the membrane semi-permeable allowing only nonpolar, non-ionized substances easy entrence into the cell
-Embedded proteins act as channels, receptors, or makers
-Polar heads = Hydrophilic
-Nonpolar tails = Hydrophobic
-Phospholipids have a nonpolar region and a polar region making them ampipathic
-75% of lipids of the cell membranes are phospholipids
5% of membrane lipids are glycolipids appearing only in layer facing extracellular fluid

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Cholesterol & Cell Membrane

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-About 20% of membrane lipids are cholesterol
-Found on both sides of bilayer
-Function is to strengthen membrane but also to allow flexibility

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Membrane structure proteins

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Includes integral & peripheral proteins

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Integral proteins

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-Extends across the bilipid layer; mostly glycoproteins
-Functions are: channels, transporters, receptors, enzymes, cell identity makers (blood maker)

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Major hystocompatability complex (MHC)

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Is a surface protein
(Immune system recognizes "self" from "non-self"

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Peripheral proteins

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-Don't extend across the bilayer
-Loosely attached to the inner & outer surfaces
-Functions include: enzymes, cytoskeleton anchors (attaching plasmalemma & cytoskeleton filamins)

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Membrane Physiology

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-Provides communication
-Allows electrochemical gradient. (Chemical ion difference: Extracellular fluid contains Na+ & Cl-, intracellular contains K+ and PO4- and negatively charged amino acids)
-Electrical gradient exists because the inside surface is more negatively charged than outside. Creates membrane potential (a voltage across membrane)

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Membrane potential

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-Occurs when pos and neg charges are separated
-Voltage = potential energy

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Electrical Gradient

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-Overall, the cell and extracellular fluid is neutral (balance in pos and neg charges)
-The voltage of cells throughout your body is normally -20mV to -200mV. (negative means inside of cell is more neg to outside)

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Sodium/Potassium Pump (Na/K Pump)

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3:2 ratio (3 Na to 2 K ratio)
-For more info, refer to Electrical Gradient flashcard

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Selectively Permeable

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4 Factors influence permeability
-Lipid solubility
-Size (large molecules can't pass through)
-Charge (Membrane is impermeable to all charged molecules and ions; they can still pass through channels)
-Presense of channels and transporters (proteins allow permeability of certain polar and charged substances that cannot pass through lipid bilayer)

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Movemend of Materials Across Membrane

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2 types of processes:
-Passive (doesn't require cellular energy such as simple diffusion, Osmosis, Filtration, Ficilitated diffusion, Dialysis)
-Active

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Simple diffusion

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Movement from areas of high to low concentration
-A concentration gradient forms when a substance is present in high amounds in one area and low amounts in another
-Net diffusion is the difference in diffusion between 2 areas
-Equilibrium is reached after a period of time
-Diffusion in the human body occurs with H2O, O, CO2, N, Steroids, etc.
-H2O diffuses via imperfections of the cell
-H2O filled channels alsow allow diffusion of Na+, K+, Ca+, Cl-, and HCO3

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Passive Processes - Osmosis

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Net movement of a solvent (water) from areas of high water concentration to areas of low concentration (Condensation)
-Direction of flow of water into/out of cells depends on Tonicity (Isotonic, Hypotonic, Hypertonic

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Isotonic

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balance of solution in two sealed areas

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Hypotonic

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Less solid, more water in a solution

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Hypertonic

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More solid, less water in a solution

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Passive Transport - Filtration

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-In filtration, water (solvent) and some dissolved substances (solute) move across a membrane due to gravity or water pressure (Hydrostatic pressure - the force of a fluid pushing against surface)
-Movement occurs from high hydrostatic pressure to low hydrostatic pressure
-Filtration occurs in our kidneys (blood forces water and small molecules through the membranes of the cell lining the capilaries - the filtered liquid then enters the kidneys)
-Dialysis is driven by concentration gradient while filtration is driven by hydrostatic pressure gradient

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Passive Transport - Facilitated Diffusion

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-Some substances are too large to pass through the plasma membranes, but can with the help of integral transports called transporters
-Glucose enters the cell this way

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Passive Transport - Dialysis

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-Dialysis is the diffusion of small solutes but not large ones through a selectively permeable membrane

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Active processes

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Active processes mechanisms require cellular energy
-Move substances against a concentration gradient
-Include: Active transport (sodium pump, symports & antiports), and Bulk transport (endocytosis, phagocytosis, pinocytosis, receptor - mediated endocytosis, and exocytosis)

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Active Transport

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-Primary active transport - Sodium pump; maintains a low concentration of sodium ions in the cytosol by pumping them out against their concentration gradient; also moves K+ pump ions in; the pump is a protein
-Secondary active transport (symports & antiports)
--Symports allow glucose and amino acids to enter the cell; the return nutrients to the blood that were filtered out by the kidneys
--Antiports keep Ca+ concentration ions low in the cytosol; helps regulate pH

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Bulk transport - Endocytosis

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-Phagocytosis (cell eating) example: membrane engulfs droplet to eat
-Pinocytosis (cell drinking)
example: oocyte drinks liquids in uterus
-Receptor mediated endocytosis

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Bulk transport - Exocytosis

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-Secretory vesicles form and secrete contents
-Important in nerve cells as they release neurotransmitters and in secretory cells that release digestive enzymes or hormones such as insulin

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Achromatopsia

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Complete lack of color vision, can be caused by damage to the Thalamus or Cerebral Cortex (damage is sometimes caused by a brain tumor)

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Cytosol contains:

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Water and solid components such as proteins, lipids, carbs, and inorganic substances

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Nucleus (the control center)

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-Surrounded by nuclear envelope
-Has 1 more nucleoli (aggregates of DNA, RNA and proteins which assemble ribosomes)
-Chromatin is DNA in a nondividing cell
-Chromosomes is during cell division, chromatin condences into chromosomes
-Histones are proteins around which DNA wraps

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Nucleus contains:

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Genes, controls metabolic activities, dictates protein synthesis, nuclear pores which allows ions and water soluble substances entrance into the cell
(DNA never leaves the nucleus)

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RNA stands for...

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Ribonucleic Acid

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3 types of RNA

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mRNA - messenger
tRNA - transfer
rRNA - rebosomal

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When and by whom was the Nucleus first described?

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In 1831 by Robert Brown

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Nucleolus is made of...

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Nucleolus = made of RNA; it's job is to synthesize rRNA

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mRNA

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Messenger RNA

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tRNA

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Transfer RNA

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rRNA

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Ribosomal RNA

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Chromatin vs. Chromosomes

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Chromatin - Non-dividing
Chromosomes - Dividing
(gametes don't have chromosomes)

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Organelles - Endoplasmic Reticulum (ER)

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2 types: Rough and Smooth (RER and SER) and are both membranes.
Means "within the cytoplasm" and "a little net"

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Rough Endoplasmic Reticulum (RER)

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-Contains ribosomes
-This is where protein synthesis occurs
-Proteins are made in the ribosomes then move through ER to the Golgi Complex
-Free ribosomes make proteins for the cells own use

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Smooth Endoplasmic Reticulum (SER)

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-Lacks Ribosomes
-Contains enzymes that synthesize carbs and lipids

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Ribosomes make...

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Ribosomes make Proteins

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SER Lipids

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Cholesterol - lipid
Testosterone - lipid
Estragen - lipid

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RER lipids

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Antibody - protein
Insulin - protein
Actin - protein
Myosin - protein
Collagen - protein
Keratin - protein

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The cells of the testes have extensive amounds of SER?

True or False?

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True
The testes make Testosterone

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Golgi Complex

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-Is membranous
-Made of cisternae
-Modifies, packages, exports proteins (through secretory vesicles)
-Forms glycoproteins or glycolipids

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Another term for Oxidative metabolism

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Cellular Respiration

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Lysosomes

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-Membranous
-Contains digestive enzymes
-Called "digestive bags" or "cellular garbage bags"
Example: WBC's contain lysosomes; Tay-Sachs occurs because of improperly functioning lysosomes (WBC's phagocytize [or eat] bacteria)

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Peroxisomes

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-Membranous
-Detoxes harmful substances
-Found in kidney and liver cells
-Contain the enzymes peroxidase and catalase to break down H2O2

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Mitochondria

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-Powerplants
-Cristae "inner membrane" which contains enzymes
-Infolding increases surface area
-Cellular respiration occurs here (forms ATP)
-Endosymbiont theory
-Exercise increases number and size of mitochondria

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ATP

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Adenosine Triphosphate

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ADP

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Adenosine Diphosphate

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Adenosine Diphosphate + Phosphate = ?

(ADP + P = ?)

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(ADP + P = ATP)

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Cytoskeleton

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Internal supporting framework of the cell
3 types of cell fibers that make up the cytoskeleton
-Microfilaments
-Intermediate filaments
-Microtubules

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Microfilaments

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-7nm
-Looks like strands of twisted beads
-Example: The protein Actin is found in skeleton muscle for contraction

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Intermediate filaments

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-10nm
-For support
-Example: The protein Keratin in the skin is made of this

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Microtubules

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-25nm
-"engines" of cell because they move things around
-Causes entire movement of cell
-Centrosome (Microtubule organizing center; important for cell division; forms microtubules necessary for cell division; made of a pair of centrioles)
-Example: Protein tubulin

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Cell Extensions (things extending from the outer cell

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3 types
-Microvilli
-Cilia
-Flagella

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Microvilli

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-Fingerlike
-Epithelial of intestine
-is for absorbsion, increases surface area

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Cilia

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-Short hair-like
-Made of 9+2 microtubular arrangement
-Found in respiratory tract and female reproductive tract

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Flagella

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-Long whip-like tail
-Made of 9+2 microtubule arrangement
-Found only on sperm cells in humans

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Cell connections

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-Integrins (proteins that holds cells in place in a tissue
-Selectin, cadherins, immunoglobulins (proteins that form cell-to-cell connections
Types of connections: Desmosomes, Gap junctions, Tight junctions

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Desmosomes

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-Fibers interlock like velcro
-Holds adjacent cells together
-Internally anchored by intermediate filaments
-Example: Skin cells

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Gap Junctions

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-Form tunnels between 2 cells so materials or electrical impulses may directly pass through
-Example: Heart muscle cells

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Tight Junctions

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-Binds adjacent cells like plastic collars on 6-packs
-Prevents leaks
-Example: Bladder or intestinal lining