Exam 1 Flashcards
Hierarchal order in the body
protons neutrons & electrons atoms biomolecules organelles cells tissue organs organ system organisms
definition of a cell
the smallest unit capable of carrying out the processes associated with life; the basic unit of both structure and function in a living organism
how many cells are found in the human body? how many different types?
100 trillion total
200 different types
largest and smallest cells in human body
largest = nerve or skeletal muscle cell smallest = sperm cell
Basic cell functions how many? and list them
7
) Obtain oxygen and nutrients.
2) Perform energy-generating reactions. (Metabolism)
(Nutrients + O2 CO2 + H2O + Energy)
3) Eliminate waste products.
4) Synthesize components needed for cell functions, structure maintenance, and cell growth. Synthesis occurs through metabolism as well
5) Control movement of materials between the cell and its environment.
6) Movement of material within the cell.
7) Sense and respond to signals indicating a change in the surrounding environment.
8) Cell division. (Reproduction) Cell division – not carried out by all cells all the time (reproduction primarily
definition of tissues
combined groups of cells of similar structure and specialized function
four primary tissue types in the body
connective tissue, muscle tissue, epithelial tissue, nerve tissue
muscle tissue
cells contract generate force allows for movement
nerve tissue
cells send electrical impulses (action potentials) relay information
epithelial tissue
Cells exchange material (between body and environment). Ex: Skin, lining of digestive tract, sweat glands also provide protective mechanism
connective tissue
Cells connect, support and anchor various body parts. Ex: tendons, bone, and blood cells.
Red blood cells (erythrocytes) carry oxygen and carbon dioxide.
White blood cells fight infection.
definition of an organ
a structure composed of tissues and cells that performs a specific function or functions
definition of a body system
a collection of organs, tissues, and cells that perform related functions and interact to accomplish a common activity essential for the survival of the human body
endocrine system organs / tissues
hypothalamus, pituitary gland adrenal gland, thyroid gland, parathyroid glands, thymus, pancreas
endocrine system functions
provide communication between cells of the body through the release of hormones into the blood stream
nervous system organs / tissures
brain, spinal cord, peripheral nerves
nervous system functions
provide communication between cells of the body through electrical signals and the release of neurotransmitters into small gaps between certain cells
musculoskeletal system organs / tissues
skeletal muscle, bones, tendons, ligaments
musculoskeletal system functions
support the body, allow voluntary movement of body, allow facial expressions
cardiovascular organs / tissues
heart, blood vessels, blood
cardiovascular sytem functions
transport molecules throughout the body in the bloodstream
respiratory organs / tissues
lungs, pharynx, trachea, bronchi
factors influencing the rate of net diffusion of a substance across a membrane
increased concentration of gradient of substance = increased effect on rate of net diffusion
increased surface area of membrane = increased effect on rate of net diffusion
increased lipid solubility = increased effect on rate of net diffusion
increased molecular weight of substance = decreased effect on rate of net diffusion
increased distance (thickness) = decreased effect on rate of net diffusion
urinary system organs / tissues
kidneys, ureters, bladder, urethra
urinary system functions
filter the blood to regulate acidity, blood volume, and ion concentrations, eliminates waste
gastrointestinal organs / tissues
mouth, esophagus, stomach, small intestine, large intestine, liver, pancreas, gallbladder
gastrointestinal system functions
break down food and absorb it into the body
immune system organs / tissues
white blood cells, thymus, lymph nodes, spleen, tonsils, adenoids
immune system functions
defend the body against pathogens and abnormal cells
integumentary system organs / functions
skin
protects the body from the external environment
homeostatically regulated factors
- Concentration of nutrients: Required to maintain needed energy
- Concentration of O2 and CO2: Required to produce adequate energy; must be eliminated to maintain pH
- Concentration of waste products: Accumulation could result in toxicity
- pH: Large fluctuations could result in cell death
- Concentrations of water, salt, other electrolytes: Required to maintain cell volume & normal cell function
- Plasma Volume and Pressure: Ensures body-wide distribution of nutrients; Ensures removal of waste products
- Temperature: Required to maintain protein integrity and function
passive transport definition
Net movement of molecules or ions from a region of higher concentration to a region of lower concentration (in other words, movement down a concentration gradient/chemical gradient) across a membrane.
No outside energy is required.
Given enough time and absence of impediment to flow, a dynamic equilibrium will be reached
factors influencing the rate of net diffusion of a substance across a membrane
increased concentration of gradient of substance = increased effect on rate of net diffusion
increased surface area of membrane = increased effect on rate of net diffusion
increased lipid solubility = increased effect on rate of net diffusion
increased molecular weight of substance = decreased effect on rate of net diffusion
increased distance (thickness) = decreased effect on rate of net diffusion
definition of osmosis
The movement (diffusion) of water through a semi permeable membrane down its concentration gradient/chemical gradient (from higher concentration to lower concentration) toward a higher concentration of solute.
solute
A dissolved substance in solution
solvent
A liquid that holds another substance in solution
In osmosis water is the _______; everything else is _____!
solvent, solute
When hydrostatic pressure _____osmotic pressure net movement of water ceases.
equals
hypo-osmotic solution
Hypo-osmotic Solution: Has a total concentration of solutes less than that in the cell
facilitated diffusion definition
Substance combines with a membrane carrier protein on one side of the membrane, is transported through the membrane, then is released on the other side.
A Type of Passive “Assisted” Transport
iso-osmotic solution
Has a total concentration of solutes equal to that in the cell
proteasome structure and function
Cylindrical protein complexes consisting of a hollow core particle capped on both ends by a regulatory particle
Degrade unwanted intracellular proteins that have been tagged for destruction by ubiquitin
tonicity definition
A measure of the effect a solution has on cell volume when the solution surrounds the cell. A function of the behavior of a cell placed in a solution.
membrane channel transport definition
Substance moves from one side of membrane to the other through a membrane channel (a pore or passage) which may always be open or which may be gated
Another Type of Passive Assisted Diffusion
If cell volume increases when placed in a solution, the solution is
hypotonic
If cell volume decreases when placed in a solution, the solution is
hypertonic
in primary active transport what is required by the transporter?
ATP
hypertonic solution
: A cell will shrink when placed in a
hypertonic solution
examples of secondary active transport
e. g. Transport of amino acids and glucose from the lumen of the intestine into the blood.
e. g. Transport of amino acids and glucose from the kidney tubules back to the blood.
facilitated diffusion definition
Substance combines with a membrane carrier protein on one side of the membrane, is transported through the membrane, then is released on the other side.
A Type of Passive “Assisted” Transport
facilitated diffusion characteristics
Concentration gradient = net diffusion Carrier molecule required Exhibits saturation kinetics Has specificity Displays competitive inhibition
specificity facilitated diffusion characteristic
The transporter will only transport molecules of a certain shape across the membrane (i.e. glucose but not amino acids)
competitive inhibition
Similar molecules compete for the same carrier
2-Deoxyglucose (2DG) is transported similarly to glucose. Less glucose is transported when 2DG is in the solution.
how is the heart rate regulated?
Working muscles use oxygen, make carbon dioxide, make lactic acid, etc.
Sensors in the body detect changes and inform the integration center in the brain which, in turn, regulates neuronal activity.
saturation kinetics definition
Transporters are transporting at maximum rate all transporters being used and moving glucose as fast as they can from an area of high to low concentration.
primary active transport examples
Sodium-Potassium ATPase Pump transports sodium out of and potassium into the cell.
Calcium ATPase Pump transports calcium out of cell or into endoplasmic reticulum
in primary active transport what is required by the transporter?
ATP
Secondary Active transport
ATP is required to generate a concentration/chemical gradient. The secondary active transporter is driven by “energy” derived from the created gradient.
examples of secondary active transport
e. g. Transport of amino acids and glucose from the lumen of the intestine into the blood.
e. g. Transport of amino acids and glucose from the kidney tubules back to the blood.
Average heart beats
70/min
100,800/day
36.8 million/yr
volume of blood pumped
7,200 L/day
2.6 million liters/year
195 million liters in 75 years
Acetylcholine ___ heart rate
decreases
Norepinephrine _____ heart rate and strength of contraction
increases
how is the heart rate regulated?
Working muscles use oxygen, make carbon dioxide, make lactic acid, etc.
Sensors in the body detect changes and inform the integration center in the brain which, in turn, regulates neuronal activity.
saturation kinetics definition
Transporters are transporting at maximum rate all transporters being used and moving glucose as fast as they can from an area of high to low concentration.
channel proteins are ___
always open
gated channel proteins
can be open or closed
Phosphorylation induces
Phosphorylation induces protein conformation change
Conformation change alters binding affinity
membrane potential
A separation of charges across the membrane; a slight excess of negative charges lined up along the inside of the plasma membrane and separated from a slight excess of positive charges on the outside
collagen definition
forms flexible but nonelastic fibers or sheets that provide tensile strength (resistance to being stretched lengthwise). Collagen is the most abundant protein in the body, making up nearly half of total body protein by weight.
elastin
is a rubbery protein fiber most plentiful in tissues that must easily stretch and then recoil after the stretching force is removed. It is found, for example, in the lungs, which stretch and recoil as air moves in and out of them.
fibronectin
promotes cell adhesion and holds cells in position. Reduced amounts of this protein have been found within certain types of cancerous tissue, possibly accounting for cancer cells’ inability to adhere well to one another; instead, they tend to break loose and metastasize (spread elsewhere in the body).
3 types of specialized cell junctions
desmosomes (adhering junctions),
tight junctions (impermeable junctions), or
gap junctions (communicating junctions).
desmosomes
Desmosomes are adhering junctions that spot-rivet cells, anchoring them together in tissues subject to considerable stretching.
tight junctions
adjacent cells bind firmly with each other at points of direct contact to seal off the passageway between the two cells found primarily in sheets of epithelial tissue
gap junctions
Gap junctions are communicating junctions made up of connexons, which form tunnels that permit movement of charge-carrying ions and small molecules between two adjacent cells.especially abundant in cardiac muscle and smooth muscle
hydrostatic pressure
is the pressure exerted by a standing, or stationary, fluid on an object—in this case, the membrane (hydro means “fluid”; static means “standing”).
osmotic pressure
is a measure of the tendency for osmotic flow of water into that solution because of its relative concentration of nonpenetrating solutes and water
osmolarity
Osmotic pressure is an indirect measure of solute concentration, expressed in units of pressure. A more direct means of expressing solute concentration is the osmolarity of a solution, which is a measure of its total solute concentration given in terms of the number of particles (molecules or ions
tonicity
tonicity of a solution is the effect the solution has on cell volume—whether the cell remains the same size, swells, or shrinks—when the solution surrounds the cell. The tonicity of a solution has no units and is a reflection of its concentration of nonpenetrating solutes relative to the cell’s concentration of nonpenetrating solutes
osmotic vs. hydrostatic pressure
Osmotic pressure is a “pulling” pressure; it is a measure of the tendency for osmotic flow of water into a solution resulting from its relative concentration of nonpenetrating solutes and water. Hydrostatic (fluid) pressure is a “pushing” pressure; it is the pressure exerted by a stationary fluid on an object.
what are the 7 basic cell functions?
Obtain oxygen and nutrients.
2) Perform energy-generating reactions. (Metabolism)
(Food + O2 CO2 + H2O + Energy)
3) Eliminate waste products.
4) Synthesize components needed for cell functions, structure maintenance, and cell growth.
5) Control movement of materials between cell and its environment.
6) Movement of material within cell.
7) Sense and respond to signals indicating a change in the surrounding environment.
All the different cell types derive from what?
the zygote
differentiation definition
Developmental process by which cells become specialized in structure to carry out specific functions
totipotent definition
Capable of forming every cell type present in the fully formed individual
atrophy
A gradual decrease in size
Example: Muscle, Adipocyte
hyperplasia
Stimulated mitotic divisions in cells by increased functional demands
Example: Callous on hands & feet
hypertrophy
The growth of an organ or tissue due to an increase in the size of its cells
Example: Muscle, Adipocyte
dysplasia
Deranged cellular growth resulting in variations in size, shape, and appearance of cells
Example: Tumors
metaplasia
The transformation of one cell type into another.
Example: Transformation of injured skin epithelia to fibroblasts which secrete collagen fibers, which aid in healing.
principles of cell theory
The cell is the smallest structural and functional unit capable of carrying out life processes.
The functional activities of each cell depend of the specific structural properties of the cell.
Cells are the living building blocks of all multicellular organisms.
All organism’s structure and function ultimately depend on the collective structural characteristics and functional capabilities of its cells.
All new cells and new life arise only from preexisting cells.
Because of this continuity of life, the cells of all organisms are fundamentally similar in structure and function.
genome
All the genetic information encoded in a complete single set of DNA in a typical body cell.
Proteome
The complete set of proteins that can be expressed by the protein-coding genes in the genome.
metabolome
The complete set of small-molecule chemicals found in a body cell.
lipidome
The totality of lipids found in body cells.
microbiome
The bacteria, viruses, and fungi found within and on the body. Each region of the body has its own, usually unique, microbiome.
epigenetics
Environmentally induced modifications of a gene’s activity that arise from chemical “tags” placed on DNA or associated proteins.
Nucleus and characteristics
The nucleus is a spheroid body within a cell. Site of expression of genetic information. As such it is the control center for the cell.
Largest structure in the cell.
Enclosed by a nuclear envelope (a double-membrane structure).
Envelope studded with openings called nuclear pores.
Contains the nucleolus: the site of ribosome biogenesis
DNA
Serves as a genetic blueprint during cell replication (“the genome”)
Provides instructions for protein synthesis (source of “the proteome”)
Provides instructions for lipid enzyme synthesis (primary source of “the lipidome”)
membranous organelles
endoplasmic reticulum, golgi complex, lysosomes, peroxisomes, mitochondria
non-membranous organelles
ribosomes, proteasomes, vaults, centrioles
parts in the cytosol
intermediary metabolism enzymes, transport, secretory, and endocytic vesicles, inclusions
active transport
Active carrier-mediated transport involving the transport of a substance against its concentration gradient across the plasma membrane
endoplasmic reticulum structure and function
extensive continuous network of fluid -filled tubules and flattened sacs, partially studded with ribosomes
Forms new cell membrane and other cell components and manufactures products for secretion
secondary active transport
A transport mechanism in which a carrier molecule for glucose or an amino acid is driven by a concentration gradient established by the energy-dependent pump to transfer the glucose or amino acid uphill without directly expending energy to operate the carrier
lysosomes structure and function
Membranous sacs containing hydrolytic enzymes
Serve as cell’s digestive system, destroying foreign substances and cellular debris
peroxisome structure and function
Membranous sacs containing oxidative enzymes
Perform detoxification activities
mitochondria structure and function
Rod- or oval-shaped bodies enclosed by two membranes, with the inner membrane folded into cristae that project into an interior matrix
Act as energy organelles; major site of ATP production; contain enzymes for citric acid cycle, proteins of electron transport system, and ATP synthase
endocytosis
en’-dō-si-TŌ-sis) Internalization of extracellular material within a cell as a result of the plasma membrane forming a pouch that contains the extracellular material, then sealing at the surface of the pouch to form an endocytic vesicle
transcytosis
pathway that shuttles large intact molecules from one side of a cell to the other, such as when materiasl are transferred from blood, through the capillaries, and into the surrounding tissue.
vaults
Shaped like hollow octagonal barrels
Serve as cellular trucks for transport from nucleus to cytoplasm
centrioles
A pair of cylindrical structures at right angles to each other
Form and organize microtubules during assembly of the mitotic spindle during cell division and form cilia and flagella
Determination of membrane potential by unequal distribution of positive and negative charges across the membrane.
When positive and negative charges are equally balanced on each side of the membrane, no membrane potential exists.
When opposite charges are separated across the membrane, membrane potential exists.
The unbalanced charges responsible for the potential accumulate in a thin layer along opposite surfaces of the membrane.
Most of the fluid in the ECF and ICF is electrically neutral.
The greater the separation of charges across the membrane, the larger the potential
resting membrane potential
The membrane potential that exists when an excitable cell is not displaying an electrical signal
membrane potential
a separation of opposite charges across the membrane, or a difference in the relative number of cations and anions in the ECF and ICF
microtubules
Long, slender, hollow tubes composed of tubulin molecules
Maintain asymmetric cell shapes and coordinate complex cell movements, specifically serving as highways for transport of secretory vesicles within cell, serving as main structural and functional component of cilia and flagella, and assembling into mitotic spindle
microfilaments
Intertwined helical chains of actin molecules; microfilaments composed of myosin molecules also present in muscle cells
Play a vital role in various cellular contractile systems, including muscle contraction and amoeboid movement; serve as a mechanical stiffener for microvilli
peroxisomes
Membranous organelles
Produce and decompose hydrogen peroxide (H2O2) while degrading potentially toxic molecules
House oxidative enzymes that detoxify various wastes
Oxidative enzymes use oxygen (O2) to strip hydrogen from certain organic molecules
Converts hydrogen peroxide into water and oxygen
differences between channel and carrier proteins
Only ions fit through the narrow channels, whereas small polar molecules such as glucose and amino acids are transported across the membrane by carriers.
Channels can be open or closed, but carriers are always “open for business” (although the number and kinds of carriers in the plasma membrane can be regulated).
Movement through channels is considerably faster than carrier-mediated transport is.
Carrier-mediated transport systems display three important characteristics that determine the kind and amount of material that can be transferred across the membrane: _______ ______ ______
specificity, saturation, and competition.
facilitated diffusion
Passive carrier-mediated transport involving transport of a substance down its concentration gradient across the plasma membrane
active transport
Active carrier-mediated transport involving transport of a substance against its concentration gradient across the plasma membrane
primary active transport
A carrier-mediated transport system in which energy is directly required to operate the carrier and move the transported substance against its concentration gradient
secondary active transport
A transport mechanism in which a carrier molecule for glucose or an amino acid is driven by a concentration gradient established by the energy-dependent pump to transfer the glucose or amino acid uphill without directly expending energy to operate the carrier
symport
The form of secondary active transport in which the driving ion and transported solute move in the same direction across the plasma membrane; also called cotransport
antiport
The form of secondary active transport in which the driving ion and transported solute move in opposite directions across the plasma membrane; also called counter-transport or exchange
vesicular transport
Movement of large molecules or multimolecular materials into or out of the cell within a vesicle, as in endocytosis or exocytosis
endocytosis
en’-dō-si-TŌ-sis) Internalization of extracellular material within a cell as a result of the plasma membrane forming a pouch that contains the extracellular material, then sealing at the surface of the pouch to form an endocytic vesicle
transcytosis
pathway that shuttles large intact molecules from one side of a cell to the other, such as when materiasl are transferred from blood, through the capillaries, and into the surrounding tissue.
purposes of exocytosis
It provides a mechanism for secreting large polar molecules, such as protein hormones and enzymes that are unable to cross the plasma membrane. In this case, the vesicular contents are highly specific and are released only on receipt of appropriate signals.
It enables the cell to add specific components to the membrane, such as selected carriers, channels, or receptors, depending on the cell’s needs. In such cases, the composition of the membrane surrounding the vesicle is important and the contents may be merely a sampling of ICF.
exocytosis
In exocytosis, almost the reverse of endocytosis occurs. A membrane-enclosed vesicle formed within the cell fuses with the plasma membrane, then opens up and releases its contents to the exterior. Materials packaged for export by the endoplasmic reticulum and Golgi complex are externalized by exocytosis.
Determination of membrane potential by unequal distribution of positive and negative charges across the membrane.
When positive and negative charges are equally balanced on each side of the membrane, no membrane potential exists.
When opposite charges are separated across the membrane, membrane potential exists.
The unbalanced charges responsible for the potential accumulate in a thin layer along opposite surfaces of the membrane.
Most of the fluid in the ECF and ICF is electrically neutral.
The greater the separation of charges across the membrane, the larger the potential
resting membrane potential
The membrane potential that exists when an excitable cell is not displaying an electrical signal
membrane potential
a separation of opposite charges across the membrane, or a difference in the relative number of cations and anions in the ECF and ICF
smooth endoplasmic reticulum
Membrane-bound tubules arranged in a looping network
Catalyzes various reactions in different organs of the body:
-In the liver – lipid and cholesterol metabolism and synthesis, breakdown of glycogen, and, along with the kidneys, detoxification of drugs
-In the testes and ovaries – synthesis of steroid-based hormones
-In the intestinal cells – absorption, synthesis, and transport of fats
-In skeletal and cardiac muscle – storage and release of calcium
lysosome
Small, membrane-enclosed, degradative organelle
Synthesized on ribosomes & transported through the Golgi
Scattered throughout cytoplasm.
Contains “digestive” enzymes including over 40 acid hydrolases.
Lysosomal membrane is resistant to its own enzymes.
Digest worn-out organelles and cellular structures, & extracellular material brought into the cell by phagocytosis.
peroxisomes
Membranous organelles
Produce and decompose hydrogen peroxide (H2O2) while degrading potentially toxic molecules
House oxidative enzymes that detoxify various wastes
Oxidative enzymes use oxygen (O2) to strip hydrogen from certain organic molecules
Converts hydrogen peroxide into water and oxygen
Methods of simple diffusion
diffusion through lipid bilayer, diffusion through protein channel, osmosis
diffusion through lipid bilayer substances involved, energy requirements and force producing movement and limits to transport
nonpolar molecules of any size (O2 CO2 fatty acids etc)
passive molecules move down concentration gradient (high to low concentration)
continues until gradient it abolished (dynamic equilibrium with no net diffusion
diffusion through protein channels substances involved, energy requirements and force producing movement and limits to transport
specific small ions (Na+ K+ Ca2+ Cl-
passive ions move down electrochemical gradient through open channels (grom high to low concentration and by attraction of ion to area of opposite charge)
continues until there is no net movement and dynamic equilibrium is established.
Osmosis substances involved, energy requirements and force producing movement and limits to transport
water only
passive water moves down its own concentration gradient (to area of lower water concentration - that is higher solute concentration
continues until concentration difference is abolished or until stopped by opposing hydrostatic pressure or until cell is destroyed
facilitated diffusion substances involved, energy requirements and force producing movement and limits to transport
specific polar molecules for which carrier is available, passive molecules move down concentration gradient (high to low)
displays a transport maximum (Tm) carrier can become saturated
carrier-mediated transport types
facilitated diffusion, primary active transport, secondary active transport (symport or antiport)
primary active transport substances involved, energy requirements and force producing movement and limits to transport
specific cations for which carriers are available (eg. Na+ K+ H+ Ca2+)
Active, ions move against concentration gradient (from low to high concentration) requires ATP
displays a transport maximum carrier can become saturated
secondary active transport (symport or antiport) substances involved, energy requirements and force producing movement and limits to transport
Specific polar molecules and ions for which coupled transport carriers are available (e.g., glucose, amino acids for symport; some ions for antiport)
Active; substance moves against concentration gradient (from low to high concentration); driven directly by ion gradient (usually ) established by ATP-requiring primary pump. In symport, cotransported molecule and driving ion move in same direction; in antiport, transported solute and driving ion move in opposite directions Displays a transport maximum; coupled transport carrier can become saturated
Vesicular transport types
endocytosis (pinocytosis, receptor-mediated endocytosis, phagocytosis)
exocytosis
pinocytosis
substances involved, energy requirements and force producing movement and limits to transport
small volume of ECF fluid also important in membrane recycling
active plasma membrane dips inward and pinches off at surface forming internalized vesicle
control poorly understood
receptor mediated endocytosis
substances involved, energy requirements and force producing movement and limits to transport
specific large polar molecule (protein)
active plasma membrane dips inward and pinches off at surface forming internalized vesicle
necessitates binding to specific receptor on membrane surface
phagocytosis
substances involved, energy requirements and force producing movement and limits to transport
multimolecular particles (eg bacteria and cellular debris)
active, cell extends pseudopods that surround particle, forming internalized vesicle
necessitates binding to specific receptor on membrane surface
exocytosis
substances involved, energy requirements and force producing movement and limits to transport
Secretory products (e.g., hormones and enzymes) as well as large molecules that pass through cell intact; also important in membrane recycling Active; increase in cytosolic induces fusion of secretory vesicle with plasma membrane; vesicle opens up and releases contents to outside Secretion triggered by specific neural or hormonal stimuli; other controls involved in transcellular traffic and membrane recycling not known
phagocytosis vs. pinocytosis
Phagocytosis and pinocytosis are specific forms of endocytosis. Solid materials enter cells by phagocytosis.
Liquids enter cells by pinocytosis.
pinocytosis
cell drinking Ingestion of membrane & fluid along with dissolved substances
receptor mediated endocytosis
Receptor (outside plasma membrane) binding of chemical messenger initiates endocytosis.
exocytosis
Release of contents of secretory vesicles from the cell
membrane potential
Membrane potential is the separation of charges across a membrane
The plasma membrane of all living cells has a membrane potential
In nearly all cell types there is a slight excess of negative charges lined up in the along the inside of the plasma membrane and a slight excess of positive charges along the outside of the plasma membrane
voltage
Pressure that causes movement of charged particles. The higher the voltage the greater the current.
current
movement of charged particles (electrons, cations, anions) from one point to another.
The _____ the resistance, the less the current.
higher
Ohm’s LAw
I = E/R I = current amps A E or V = Voltage (volts V) R = Resistance (ohms ) V=IR
Nernst equation
The Nernst Equation tells us what voltage must be applied (to side A compared to side B) to prevent diffusion of an ion down its specific concentration gradient (in this example: Potassium):
permeability of cell membrane is a function of
Size of molecules (larger – harder) ; Solubility in lipids; Ionic charge (greater the charge the more difficult ot pass); Presence of channels (have openings that allow for some specific molecules to pass) and carrier molecules. (made of proteins that carry molecules from one side to another)
plasma membrane is composed of
The “Gate Keeper”
-Semi-permeable: Permits selected material to pass through
Composed of: Lipid (phospholipids & cholesterol) (43%); Protein (55%); Carbohydrate (2%)
phospholipid structure and function
Polar ends of phospholipids are
Hydrophilic (like water) & lipophobic (don’t dissolve in lipids)
Non-polar fatty acid tails are Hydrophobic (don’t like water) & lipophylic (dissolve in lipids)
Functions
Help establish a semi-permeable barrier
Contributes to membrane fluidity
functions of cholesterol
Membrane fluidity-
Prevent adjacent fatty acids from forming crystals
Membrane Stability-
Association with phospholipid stabilizes their position
lipid raft function
Reception of extracellular communication
made up mostly of sphingolipids
3 types of proteins and functions
Integral Proteins
Embedded within plasma membrane
Transmembrane Proteins
Span the width of the membrane
Peripheral Proteins Partially embedded on one (either) side of the membrane Structure Enzymes Receptors Channels Gated Channels
enzymes
Enzymes - (enhance rate that chemical reactions occur message communication and alteration of membrane itself)
carbohydrateds and function
Carbohydrates Present on surface of the cell membrane as: Glycoproteins Glycolipids Form a “Sugary Husk” The “Glycocalyx”
Functions
Protect the cell surface
Keep cells together
Role in “self-recognition” processes
Prevent over-population
microvilli definition and function
Closely spaced, finger-like projections
Structure derived from cytoskeletal elements
Located on most epithelial cells
Increase surface area
stereocilia
(elongated microvilli)
Composed of cytoskeletal elements
Located on hair cells & on epididymal cells
functions Functions Sensory Transmission (balance & hearing)
Absorption (movement)
cilia and function
(elongated, motile extension of cell)
Extremely complex structurally
Located in most organs
Movement of fluid, particles, & cells
diffusion
Net movement of molecules or ions from a region of higher concentration to a region of lower concentration (in other words, movement down a concentration gradient).
No outside energy is required.
diffusion and ion concentration in the body
Dependent on differences in solute concentration.
Common between the inside and the outside of cells.
Also between intracellular compartments.
Concentration of potassium is much _____ on inside of cell than outside of cell
Concentration of sodium is greater on ____ of cell than the inside of cell
Same with calcium (greater on outside of the cell) (comparing to calcium in the cytosol)
potassium greater inside than outside
sodium concentration and calcium concentration are greater on the outside of the cell than the inside
passive transport
Net movement of molecules or ions from a region of higher concentration to a region of lower concentration (in other words, movement down a concentration gradient/chemical gradient) across a membrane.
No outside energy is required.
Given enough time and absence of impediment to flow, a dynamic equilibrium will be reached.
factors influencing the rate of net diffusion of a substance accross a membrane (increase or decrease effect on rate of net diffusion?)
increase in concentration gradient substance, increase of surface area membrane and increase of lipid solubility will increse the effect on rate of net diffusion
increase in molecular weight of the substance and increase in distance (thickness) will decrease the effect on rate of net diffusion
