General principles Flashcards
(53 cards)
Define: homeostasis
Maintaining nearly constant conditions in the internal environment (i.e. a steady state)
What is the difference between equilibrium and steady state?
Equilibrium does not require energetic input. Steady state does.
Additionally, in equilibrium, parameters are constant in time. In a steady state, they are nearly constant.
Define: Organ, Organ system
Organ: composed of 2 or more kinds of CT
System: A collection of organs that perform a general function
Define: Mass balance for a system at steady state
Any substance taken in is nearly equal to the amount leaving the body
Define: Basal Metabolic Rate
Energy expenditure at rest in kcal/hr/sq meter surface area
What accounts for most (20-30%) of basal metabolic rate?
Skeletal muscle
What are some factors that influence metabolic rate?
Age, gender, activity level, hormones, climate, nutrition status
Why is positive feedback rarely used?
It accelerates a process and can be unstable
Define: gain
The capacity of a system to restore a controlled variable to its set point after perturbation.
Mathematically, it is correction/remaining error
Give some examples of positive feedback in the body
Contractions in childbirth, blood clotting, estrogen effects on pituitary-hypothalamus before ovulation, action potential, bleeding out after excessive blood loss
What is the goal of negative feedback?
To bring a variable back to a set point, opposite the change that has occurred
Define: active transport
Moving a solute from a region of low electrochemical potential to a region of high potential. Up the gradient. Requires energy
Define: passive transport
Moving a solute down its electrochemical potential gradient (from high to low). Does not require energy
Define: thermodynamic equilibrium
When chemical and electric driving forces on a solute are equal and opposite in direction so the net driving force is zero
What type of transport is a pump?
Primary active
Give two examples of secondary active transport
Symporter carrier proteins and antiporter/exchanger carrier proteins
What type of transport is an ion channel?
Passive transport
Is simple diffusion mediated or unmediated?
Unmediated
Which is faster, facilitated diffusion through a carrier protein (uniporter) or through an ion channel?
Ion channel, by many orders of magnitude
Protein-mediated transport can be _____ at high concentrations of solute
Saturated
What is the difference between competitive and noncompetitive transport inhibition?
Competitive inhibition can be overcome by an increase in solute concentration. Noncompetitive can not.
Define: electrogenic
When the charge transfer from one side of the membrane to the other is unequal, producing a net charge (i.e. Na+/K+ antiporter produces a net positive charge outside of the cell)
Define: endotherm
An animal that generates its own body heat. Ex. a human.
Define: homeotherm
An animal that maintains a core body temperature in a narrow range. Ex. a human.
