Ch. 4: Cell Physiology II Flashcards
What are 3 types of diffusion
Simple diffusion
Osmosis
Facilitated diffusion
What is involved in bulk transport
Endocytosis -fluid endocytosis (pinocytosis) -receptor mediated endocytosis -phagocytosis Exocytosis
What is simple diffusion
A substance passes through a membrane without the aid of an intermediary such as an integral membrane proteins
What is osmosis
Net diffusion of water
-water moves from an area of high water concentration to an area of low water concentration
-Or low solute concentration to high solute concentration
Water diffuses across the plasma membrane of most cells very rapidly via membrane protein channels (aquaporins) that are generally always open
Water concentration is influenced by
Solute(anything dissolved in a solution)
Low solute concentration to high solute concentration (Osmosis)
High water concentration to low water concentration (Osmosis)
In osmosis membrane is permeable to water but not _________
Solutes
What happens to intracellular fluid volume and cell size when the concentration of water soluble intercellular solute simple glucose is higher than normal?
The volume of intracellular fluid goes up in the size increases hypotonic
Solute concentration also goes up
What then happens to the concentration of the solute (glucose) in the intercellular fluid
The solute concentration in the intracellular fluid goes up and needs a protein carrier to get out
What that happens to the concentration of the other solutes in the intercellular fluid example potassium
The concentration of the other cells become diluted because water enters the cell by diffusion
Membrane is permeable to water but not________
Solutes
In response to _________the membrane generally becomes permeable to one or more solute to compensate
Osmosis
Temporary loss of homeostasis
What happens to extracellular fluid volume and solute concentration when a person is dehydrated?
Dehydration causes loss of some of the extracellular fluid
Water is going to enter the extracellular space via osmosis to compensate for the loss of fluid through sweat
Dehydration causes the cell to be
Hypertonic
cell shrinks
Water is low solute is high
During normal activity of the cell what state is it in
Isotonic solution
No change in cell volume
During hyper-hydrated time what is the state of the cell
Hypotonic solution
cell swells
Solute is low water is high
What is facilitated diffusion
Transport of water-soluble molecules down a concentration gradient (from high to low) via an integral proteins functioning as a carrier
-ex.) glucose and amino acids
What are some characteristics of the facilitated diffusion
Specificity-Carrier proteins are specific to a particular water soluble factor
-ex.) glucose carrier transports ONLY GLUCOSE
bidirectional-extracellular ——->
Facilitated diffusion always has a
Examples as it relates to glucose
-Carrier protein
-Most cells, the extracellular glucose is higher than the intracellular concentration
-In cells of the liver, small intestine lines, and kidney, glucose can be higher in the cytoplasm relative to the extracellular fluid
Extracellular
Liver stores glucose as what
Glycogen
True or false Most cells have a lower concentration inside the cell and a higher concentration outside cell
True
True or false Cells of the liver, small intestines, and kidney have high concentration inside the cell and low concentration outside the cell
True
What takes place in membrane transport
Diffusion
active transport
bulk transport
Describe saturation facilitated diffusion
Most cells have carrier proteins for water-soluble molecules(ex.) glucose transporters) on their plasma membrane in in on simulated/basal state
-allows for basal/low level uptake of water soluble molecules
Following simulations a population of carriers held in reserve in the cytoplasm move to the plasma membrane
-increased uptake rate of transport of water soluble molecule
All cells use _______ to take up energy
Glucose
Only can transfer as many molecules as there are_________
Receptors
What is active transport
Requires energy
energy ATP dependent
transports water soluble molecules across the plasma membrane against its concentration gradient
Could be a channel or carrier
K and Na transport at the same time through the _________
Active transport carrier itself is an ______ that breaks down ATP for energy
Sodium potassium pump
ATPase
Potassium goes from ______concentration to _____ concentration
Sodium goes from ____concentration to _____concentration
Low to high
High to low
What is bulk transport?
Water soluble molecules are transported in bulk Energy ATP dependent Types of bulk transport processes -endocytosis -exocytosis
What is endocytosis
Internalization of components of the extracellular fluid
- fluid endocytosis pinocytosis “cell drinking”
- receptor mediated endocytosis
- Phagocytosis-cell eating
What is exocytosis
Secretion of intercellular components to the extracellular fluid
What is fluid endocytosis
Sell drinking pinocytosis
The transport of fluid into a cell by means of local infoldings by the cell membrane so that a tiny vesicle Orsak forms around each droplet which is then taking into the inner of the cytoplasm
What is receptor-mediated endocytosis
Process by which Celebes swords molecules by the inward budding of plasma membrane vesicles containing proteins which help in binding the particular molecules necessary for the cell
What is phagocytosis?
Types of white blood cells
Phagocytic cells
Engulfing of micro organisms or other cells in foreign particles by phagocytes
What is exocytosis
Secretion of products synthesized by cells
example neurotransmitters
All cells can perform exocytosis
What is the importance of balance
What would happen to a cell size if the rate Endocytosis is greater then exocytosis -The size would get smaller Endocytosis is less than exocytosis -The size will get bigger
How might these scenarios impact ability of a cell to maintain homeostasis
If the cell needs more something they can engulf more or vise versa
What is maintenance of cell size
Rate of exocytosis=rate of endocytosis
What is membrane potential of cell physiology
A voltage difference exist across the plasma membrane of all cell
Resting or quiescent
-intercellular surface negatively charged
-extracellular surface positive charge
______________ -negative charge is attribute of all to fixed molecules or proteins that are negatively charged
- membrane proteins
- ATP
Intracellular surface
____________Positive charge mainly attribute all to positively charged ions
Sodium (Na+), which is found in (high) in the extracellular fluid
Relative permeability of potassium is
50-75
What are some factors that influence Intracellular ion concentrations
Chemical forces
- electrochemical force
- opposite charges are attracted to each other - diffusion force
- concentration gradient across membrane
Factors that influence intracellular ion concentration is stare of ion channels
Open of closed ion channels
Movement of sodium potassium only occurs when the channels are open, regardless of the existence of electrochemical or diffusion force
Na+/ K+
What are ion channels
Primary ion channels implements membrane potential
-K+ channels
-Na+channels
voltage regulated ion channels
-Open/close in response to changes in membrane potential (voltage)
plasma membrane’s are more permeable to potassium relative to sodium in a resting cell leaky to potassium
-higher percentage of potassium channels are open relative to sodium channels when a cell is at its resting membrane potential for (low-voltage)
more potassium is ________ a cell
Inside
What is the normal range of membrane potential
-62 to -90 mV
Increase in membrane potential in target cell
What happens with an increase in membrane potential
If the membrane potential rises to a threshold value the membrane/cell becomes activated, resulting in action potential
What is depolarization
Increase in membrane potential
What is repolarization
Return of the membrane potential to resting levels
What is hyperpolarization
decrease in membrane potential relative to resting levels
Channels open and close in response to
Membrane potential
Continued entry of potassium into the cytoplasm will cause the membrane potential to __________
increase
Increase member potential above the threshold value causes an action potential and hence__________ the cell
Activate
What is a hypothetical example of resting membrane potential
Skeletal muscle cells contracting without a stimulus from nervous system
Neurons firing without a stimulus from higher brain centers
What maintains homeostasis of a cell’s membrane potential and bus prevents spontaneous activation of cells
The potassium needs to be higher in the intracellular fluid
the sodium potassium pump
