BIPN 100 Lecture Notes - Lecture 3: Goldman Equation, Membrane Protein, Nernst Equation
26 Jun 2018
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BIPN100 Lecture 3 Notes 4/6/18
- Control of homeostasis through nervous system (fast) and endocrine system (slow)
oHomeostasis maintained through feedback loops
oEx: component 1 affects component 2. Component 2 affects component 3. Component
3 affects component 1.
- Types of feedback loops
oNegative feedback systems
Reverses change in a controlled condition to bring
back to normal conditions
Variables tend to remain at constant values
Odd number of negative signs (signal inversions)
For temperature regulation, blood glucose levels, and blood pressure
Ex: air conditioner. Controlled variable is temperature. If temperature increases,
sensor (thermometer) has increased reading. Thermometer
sends signal to integrator (thermostat) which compares the
measurement of the thermometer to a set point. The
difference between the set point and the thermometer
reading has increased, so the integrator sends a signal to
the controller (air conditioner) to increase activity
Ex: if scared, heart rate increases and blood pressure increases. Baroreceptors sense
change in pressure and send nerve impulse to brain (integrator). Brain compares
information with set point that blood pressure should be. If there’s a difference,
brain sends nerve impulses to heart (effector) to decrease heart rate and blood
pressure (response), bringing physiological conditions to normal
oPositive feedback systems
Strengthen or reinforce a change in the controlled variable
No sign inversion, or even number of negative signs
Often pathological, except for normal child birth or blood clotting
Ex: You get infection and white blood cells start attacking virus. White blood cells
release chemicals in the blood which signals the hypothalamus to produce
prostaglandins to increase the set point of the temperature of your body. Brain
thinks that you’re cold and increases your temperature more, causing fever to help
kill virus. Feedback interrupted once infection is killed
Ex: Child birth. Contractions of uterus cause head of baby to stretch cervix. Stretch
receptors in cervix wall sends nerve impulse to brain to release oxytocin. This is
released into bloodstream to muscle walls of uterus to cause more contractions,
pushing the baby more, stretching the cervix more, and causing the stretch
receptors to send more signals to release oxytocin. Feedback stops once baby is out
- Resting membrane potential
oElectrical force
Cation: ion with positive charge
Anion: ion with negative charge
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Document Summary
Control of homeostasis through nervous system (fast) and endocrine system (slow: homeostasis maintained through feedback loops, ex: component 1 affects component 2. Types of feedback loops: negative feedback systems. Reverses change in a controlled condition to bring back to normal conditions. Variables tend to remain at constant values. Odd number of negative signs (signal inversions) For temperature regulation, blood glucose levels, and blood pressure. If temperature increases, sensor (thermometer) has increased reading. Thermometer sends signal to integrator (thermostat) which compares the measurement of the thermometer to a set point. The difference between the set point and the thermometer reading has increased, so the integrator sends a signal to the controller (air conditioner) to increase activity. Ex: if scared, heart rate increases and blood pressure increases. Baroreceptors sense change in pressure and send nerve impulse to brain (integrator). Brain compares information with set point that blood pressure should be.
