Physiology Lecture 2 Flashcards
Distribution of H2O in the body
-40L
-57% of total weight
-67% found in the intracellular compartment
-33% found in extracellular compartments
-20% of that 33% is found in the blood (forms the blood plasma)
The other 80% is found between the cells (interstitial fluid)
Distribution of Molecules in different body compartments
NA+ 140mmol/L in EFC, 15mmol/L in IFC
K+ 4mmol/L in EFC, 150mmol/L in IFC
MATERIALS MOVE FROM ________ TO _________UNLESS ARE SOME HOW PREVENTED FROM DOING SO!!!!!!!!!!!
High concentration to low concentration
What is diffusion?
Movement of particles down a concentration gradient resulting in equal distribution of particles
What biological molecules move by simple diffusion?
Oxygen, nutrients, and small molecules
As molecules become warmer, they ______.
Move more quickly
With a freely permeable membrane, do molecules still move down their concentrationo gradient?
Yes
What organ is reliant on diffusion?
Kidneys
If a membrane is semipermeable to small molecules but not large molecules what happens?
There will be an equal distribution of small molecules on either side but the large molecules will stay on one side.
Cell membrane is often referred to as the ________ and is composed primarily of ______ and _______.
Lipid bilayer
Lipids and proteins
Difference between hydrophilic and hydrophobic molecules.
Hydrophilic
- Water loving
- Interact w/ charged (polar) molecules
- proteins, vitamins, ions, hormones
- Difficult to move across cell membrane
Hydrophobic
- Water hating
- Interact w/ uncharged (non-polar) molecules
- ETOH, fatty acids, steroids
- More easily move across cell membrane
Would our cells work if they were either completely permeable or completely impermeable?
No, we want to be able to regulate what’s allowes through the membranes
Plasma membranes are leaky
This unequal distribution of ions creates a membrane that tends to be __________ on the inside and _______ on the outside.
Negatively charged on the inside and positively charged on the outside
A failure to appropriately regulate/ control/ manage transport process disrupts _______.
homeostasis
Which molecules move through the membrane very rapidly?
Non-polar (uncharged, lipid soluble, hydrophobic)
Increasing the lipid solubility of a molecule will _________.
Increase its rate of diffusion across the lipid bilayer.
Ions are polar and thus…
Have difficulty moving across the membrane
What are ion channels?
Openings that allow specific charged molecules to move through
The concentration gradient also creates an __________.
Electrical gradient
Ion channels allow for regulation of the movement of ions. The resulting seperation of charges creates an electrical gradient which influences ion movement in what way?
Pulls positive ions (+) into a cell
Pulls negative ions (-) out of the cell
Occurs because the inside of the cell is negatively charged.
What is the electrochemical gradient?
It is the combination of both the electrical and concentration gradients.
In a cell at rest, what is the Resting Membrane Potential?
-60 to -75 mV
Movement through ion channels is regulated by?
Concentration gradient and charge
What is mediated transport?
Involves using transporters to move molecules through the membrane. Transporter molecules may move molecules up or down a concentration gradient.
Glucose is dependent on _____________.
Mediated transport system
Where is GLUT4 primarily found?
Muscle tissue
What is defective in type 2 diabetes?
Transporter
With type 2 diabetes we want to improve the functionality of glucose transporters, thus increase uptake of glucose.
What 3 factors determine the magnitude of solute flux achieved through a mediated transport system
- The number of transporters available
- The speed at which transporters undergo conformation change and move the solutes
- Extend to which the binding sites are saturated
What is facilitated diffusion?
Net movement remains from high to low concentration but doesn’t go through the membrane on its own. It uses transporters across the membrane.
L2S52
What is active transport?
Requires energy (ATP)
Molecules can move from low-to-high or high-to-low.
Involves the expenditure of ATP and specific carrier molecules or biological pumps
Net Effect
A shape change in the pump occurs that extrudes 3 Na+ ions into the extracellular fluid for every 2 K+ moved into the interior of the cell
inside of cell becomes negatively charged. K+ > Na+
T or F. Membranes are slightly permeable to NA+.
False.
Membranes are slightly permeable to K+ (leaky), but are relatively impermeable to Na+
What is endocytosis?
Process by which a piece of the cell membrane engulfs an organism, molecule, etc. The resulting vesicle then enters the cell and is degraded
Phagocytosis
What is exocytosis?
Opposite on endocytosis.
Vesicle formed inside cell, fuses with membrane releasing the contents into the extracellular space.
Example is insulin
What is osmosis?
The movement of water molecules from high water conc to low water conc.
What does adding a solute to water do in regards to its concentration?
Decreases the concentration of water in the solution
Solutes that cannon cross a membrane and promote osmosis are called _______.
What are some examples?
osmotically active molecules
Hemoglobin in red blood cells are osmotically active
Large proteins (often carry electrical charges) are osmotically active
The movement of water across a membrane that is permeable to water but not to solute leads to an equilibrium state ____________.
…involving a change in the volumes of the two compartments.
What is osmotic pressure?
The force required to stop the osmotic movement of water.
Hypertonic solution
blood cells have more water so they come out of red blood cells
Hypotonicity vs Hypertonicity
Hypotonicity: has a lower concentration of solutes than another solution; higher concentration of water
Hypertonicity: has a greater concentration of solutes than another solution; lower concentration of water
What is the epithelium?
The outside layer of cells that covers all the free, open surfaces of the body including the skin, and mucous membranes that communicate with the outside of the body.
What is the endothelium?
is the layer of cells lining the closed internal spaces of the body such as the blood vessels and lymphatic vessels
