True or False
Plasma membrane is selectively permeable--allows only certain kinds of molecules to pass.
True
What type of transport involves specfice protiens?
Carrier-mediated transport involves specific protein transporters
What type of transport occurs by diffusion.
Non-carrier mediated transport occurs by diffusion
Describe "Passive Process".
Passive processes - substances move across cell membranes without the input of any energy; use the kinetic energy of individual molecules or ions
Describe "Active Process".
Active processes - a cell uses energy, primarily from the breakdown of ATP, to move a substance across the membrane, i.e., against a concentration gradient
What factors influence diffusion?
Steepness of concentration gradient
Temperature
Mass of diffusing substance
Surface area
Diffusion distance
Simple diffusion.
This is Channel Mediated Diffusion.
This is Carrier Mediated Diffusion
True or False
Non-polar compounds readily diffuse thru cell membrane
True
Cell membranes are impermeable what?
Charged and most polar compounds.
What makes it possible for charged molecules to move across the membrane.
Charged molecules must have an ion channel or transporter to move across membrane
What is Osmosis?
Net movement of water through a selectively permeable membrane from an area of high concentration of water (lower concentration of solutes) to one of lower concentration of water.
How does water pass through the plasma membrane?
Through lipid bilayer by simple diffusionthrough Aquaporins, integral membrane proteins.
H2O diffuses down its concentration gradient until its concentration is equal on both sides of a membrane. Some cells have water channels (aquaporins) to facilitate osmosis
What is Osmotic Pressure?
Is the force that would have to be exerted to stop osmosis
Indicates how strongly H2O wants to diffuse
Is proportional to solute concentration
What is OSM?
Osmolality (Osm) is total molality of a solution. Or the total concentration of the solute present in the solvent.
The effect of a solution on osmotic movement of H2O is what?
Tonicity
A solution that has the SAME osmotic pressure is referred to as what?
Isotonic solutions have the same osmotic pressure
Hypertonic solutions. . .
Have higher osmotic pressure and are osmotically active
True or False?
Hypotonic solutions have higher osmotic pressure and are osmotically active.
False.
Hypotonic solutions have LOWER osmotic pressureand are osmotically active
This solution is Isotonic. Thus there is no change in the blood cell. It is normal.
This solution is hypertonic.The Cell shirnks and undergoes Creantation.
This Solution is Hypotonic and the cell swells undergoing
Hemyolsis.
Blood osmolality is maintained in a narrow range around what level?
Blood osmolality is maintained in a narrow range around 300mOsm.
If dehydration occurs what happens?
If dehydration occurs, osmoreceptors in hypothalamus stimulate:ADH release & Thirst. Which causes kidney to conserve H2O and Drinking
Molecules too large and polar to diffuse are transported across membrane by protein carriers in a process called what?
Carrier-Mediated Transport
What is Facilitated Diffusion?
Is passive transport down concentration gradient by carrier proteins.
This is the K+ Pump (Potassium pump)
Channel-mediated Facilitated Diffusion of Potassium ions through a Gated K + Channel.
Protein carriers exhibit: Specificity for single molecule Competition among substrates for transport. Saturation when all carriers are occupied. This is called Tm. What type of transport is this?
Carrier-Mediated Transport
Solutes are transported across plasma membranes with the use of energy, from an area of lower concentration to an area of higher Concentration Sodium-potassium pump. By what means is this accomplished?
Active Transport
Na+/K+ Pump what's signifigant about this?
Uses ATP to move 3 Na+ out and 2 K+ in.
Against their gradients
Define Secondary Active Transport.
Requires ATP to first move Na+ uphill to create a gradient. Secondary active transport then uses energy from “downhill” movement of Na+ to drive “uphill” transport of another molecule.
Cotransport (symport) is what?
Secondary transport in same direction as Na+
What is it called when molecule move in opposite direction to Na+?
Countertransport (antiport)
Define a vesicle.
A small spherical sac formed by budding off from a membrane.
Endocytosis is what?
Materials move into a cell in a vesicle formed from the plasma membrane.
What are the 3 types of Endocytosis?
Receptor-mediated endocytosis Phagocytosis
Bulk-phase endocytosis (pinocytosis)
Vesicles fuse with the plasma membrane, releasing their contents into the extracellular fluid is defined as what?
Exocytosis.
Transcytosis is what?
A combination of endocytosis and exocytosis
Bulk Transport does what?
Moves large molecules and particles across plasma membrane.
Occurs by endocytosis and exocytosis
Phagocytosis is also refered to as what?
Cell eating.
Transcellular transport does what?
Moves material from 1 side to other of epithelial cells
What is the term for "moves material through tiny spaces between epithelial cells"?
Paracellular transport
True or False?
Transport between cells is limited by junctional complexes that connect adjacent epithelial cells.
True.
What is a Tissue?
Group of similar cells
Common embryonic origin
Common function
And they work together to carry out specialized activities
The study of tissue is what?
Histology
What does a Pathologist do?
Looks for tissue changes that may suggest a disease state.
What is Epithelial Tissue?
Covers surfaces, cells contact with other cells
Lines hollow organs, cavities and ducts
Forms glands when cells migrate beneath the surface
Generally material (matrix) is found between cells
Protects, Supports and Binds structures together
Stores energy as fat
Provides immunity
Connective Tissue
What is Muscle Tissue?
Cells shorten in length generating the physical force needed to put body structures in motion
Generates body heat
Nerve Tissue
Cells that conduct electrical signals
Monitors/detects changes inside and outside the body
Coordinates body activities through the generation of nerve impulses
What are the Primary germ layers within the embryo?
Endoderm
Mesoderm
Ectoderm
Epithelial Tissue develops from where?
Epithelial Tissue develops from all 3 germ layers
Connective & Muscle Tissue develops where?
Connective & Muscle Tissue develops from mesoderm.
Nerve Tissue develops from where?
Ectoderm.
What is a biopsy and what is the purpose?
Removal of living tissue for microscopic examination
Useful for diagnosis, especially cancer
Tissue is preserved, sectioned and stained in preparation for microscopic viewing
Define the following junction.
Adherens Junctions
What's unique about Adherens Junctions?
Holds epithelial cells together at specific points
Structural components
A plaque contains a dense layer of protein within the cell membrane
Microfilaments extend into and through the cytoplasm (belt)
Integral membrane proteins (cadherins) connect the membranes of cells
Common in tissues subjected to friction and stretching
Outer layer of skin, cardiac muscle and GI tract
Define the following junction.
Desmosomes
What is unique about Desmosomes?
Resists cellular separation and cell disruption
Similar structure to adherens junction except intracellular intermediate filaments cross cytoplasm of cell to desmosomes on the other side of the cell
Prevent epidermal cells from separating under tension and cardiac muscles cells from pulling apart during contraction
Define the following junction.
Gap junction.
What is unique about a Gap junction?
Connect neighboring cells via tiny fluid-filled tunnels called connexons
Contain membrane proteins called connexins
Plasma membranes of gap junctions are separated by a very narrow intercellular gap (space)
Communication of cells within a tissue
Ions, nutrients, waste, chemical and electrical signals travel through the connexons from one cell to another
Define the follwing junction.
Hemidesmosomes
What is unique to Hemidesmosomes?
Resemble half of a desmosome
Do not link adjacent cells but anchor cells to the basement membrane (extracellular material)
Contains transmembrane glycoprotein integrin
Integrins attach to intermediate filaments and the protein laminin present in the basement membrane
Define the following junction.
Tight junction.
What is unique about a Tight junction?
Web-like strands of transmembrane proteins Fuse cells together
Seal off passageways between adjacent cells
Common in epithelial tissues of the stomach, intestines, and urinary bladder
Help to retard the passage of substances between cells and leaking into the blood or surrounding tissues
Muscle Cells consist of what?
Consists of elongated cells called muscle fibers or myocytes
Cells that shorten
What cells provide us with motion, posture and heat