Composition of Cells Flashcards
What is the typical volume of plasma?
3L
What is the typical volume of extracellular fluid?
13L + 5L for “third space”
What is the typical volume of intracellular fluid?
27L
What is the ICF [Na+]?
14mM
What is the ECF [Na+]?
140mM
What is the ICF [K+]?
145mM
What is the ECF [K+]?
5mM
What is the ICF [Cl-]?
5mM
What is the ECF [Cl-]?
145mM
What is the ICF [A-n]? (big anions)
126mM
What is the ECF [A-n]? (big anions)
~0mM
What is the ICF [H2O]?
55,000mM
What is the ECF [H2O]?
55,000mM
Is the membrane permeable to Na+?
functionally impermeable
Is the membrane permeable to K+?
yes
Is the membrane permeable to Cl-?
yes
Is the membrane permeable to A-n (big anions)?
no
Is the membrane permeable to H2O?
yes
What 2 important properties of plasma membranes is conveyed by lipids?
- impermeable to charged substances (including molecules with dipoles)
- Can maintain separation between opposite charges without collapsing. (allows for creation of membrane potential)
What are 2 important properties of channels?
- Most are selective for specific ions
2. Some contain gates - substances can only pass through when the gate is open
What physical forces can determine the gating properties of ion channels?
Electric field (voltage gated)
mechanical (hair cells in cochlea, touch receptors)
chemical (neurotransmitter synapse)
temperature (cutaneous thermal receptors)
What are water channels called?
aquaporins (contain no gate)
What types of molecules pass through channels?
H2O
Ions: Na+, K+, Cl-, Ca2+
How is primary transport different from secondary transport?
Primary depends on energy released directly by metabolism (often ATP)
Secondary depends on other sources (i.e. E releases when Na+ leaks into cells through channels)
How are transporters different from channels?
require E
Slower (max of several hundred cycles per sec)
transport ions and smaller ions
What types of molecules are transported by transporters?
glucose (large molecules)
Ions (Na+)
