CHAPTER 1 Flashcards
Homeostasis
Maintenance of internal conditions, stability via negative feedback loop.
Negative Feedback
Initiation of responses that counter deviations of a variable from normal range
What is the main goal of homeostasis?
To maintain optimal conditions for cellular function
What are the four components of Negative Feedback?
- Set point (target)
- Sensors/receptors (monitor the controlled variable)
- Comparator (input fro receptors determine when deviations occur initiating response)
- Effectors (restore set point to its normal level)
Two major functional compartments of body fluid
Intracellular Fluid (ICF)- 60% of vol & Extracellular Fluid (ECF)- 40% of volume
What are the two components that make up the extracellular fluid and their proportion?
Interstitial Fluid (80% of ECF)
Plasma (20% of ECF)
Concentration of Na+, K+,CI- and Protein in ICF
Sodium- low
Potassium- high
Chloride- low
Protein- high
Concentration of Na+, K+,CI- and Protein in interstitial fluid?
Sodium- high
Potassium- low
Chloride- high
Protein- should be zero! (Do not want protein here)
Concentration of Na+, K+,CI- and Protein in plasma
Sodium- high
Potassium- low
Chloride- low
Protein- low
Active Transport uses __
ATP
Primary vs Secondary Active Transport
Primary- membrane proteins that directly couple ATP hydrolysis to movement
Secondary- movement of two solutes together, energy is used to develop a driving force for one solute which is then used to power the transport of another.
What were the four examples of primary active transport?
Ca2+/ATPase
H+/ATPase
H+/K+ATPase
MDR (multi-drug resistance) transporters
Na2+/K+ATPase
- example of primary active transport
- 3 sodium in, 2 potassium out
- Accounts for high sodium outside the cell and high potassium inside the cell.
Ca2+/ATPase
- example of primary active transport
- plasma mean-brand and endoplasmic reticulum; functions to keep low intracellular calcium
H+/K+ATPase
- example of primary active transport
- hydrogen out the cell for potassium in
- acidic gastric juice in stomach
MDR transporters
- example of primary active transport
- extrude molecules from cell
- expressed in the liver, kidney and BBB
H+-ATPase
- example of primary active transport
- inside cells, acidified lysosomes
What are the two types of Secondary active transport?
Cotransporters (symporters)- same direction
Exchangers (antiporters)- opposite directions
Passive Transport
- does not require ATP
- only occurs along favorable electrochemical gradient
What is the driving force for diffusion?
Permeability
Membrane permeability is proportional to ________ and inversely proportional to ___________.
Lipid solubility
Molecular size
E.g. gases move easily because lipid soluble and small!
Simple Diffusion
(passive transport)
Along concentration gradient
Facilitated diffusion
(passive transport)
-faster than simple diffusion; saturation of the transport at high solute concentration
Ficks Law of Diffusion
Net flux per unit area is a factor of PERMEABILITY of the solute and the concentration difference of that solute across the membrane.
(Basically: 1. is it even permeable? 2. Does it favor the concentration gradient?)
Permeability is the driving force of _______
Diffusion
What are three examples of gated ion channels?
Voltage-gated
Ligand-gated (chemicals)
Mechanical forces (e.g. stretch-activated)
