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.
