Chapter 1 - Homeostasis
Steps in the response loop of a reflex control pathway
-2 parts: response loop and feedback loop -Stimulus - sensor - input signal - integrating center - output signal - target - response
What is compartmentation? Where does it occur?
-Allows a cell/tissue/organ to specialize and isolate functions -Body cavities, hollow organs, organelles create compartments
What are the key concepts of structure/function relationships
-Compartmentation -Mechanical properties of cells, tissues, organs -Molecular interactions
Explain the positive feedback loop during birth
-Fetus drops lower in uterus -Causes cervical stretch -^Stimulates oxytocin release -^Release causes uterine contractions -Baby pushes against the cervix because of the contraction -Cervical stretch occurs again
What are the key concepts of communication
-Information flow -Mass flow
Define set point as related to homeostatic systems
-Optimum value -Can oscillate -Can change (ex. temp set point as a result of the menstrual cycle)
Biorhythms
-Repeating patterns/cycles of change -Ex. circadian rhythm, body temp
Describe the negative feedback loop related to fish tank
-Stimulus: water is below set point -Sensor: thermometer senses temp decrease -Input signal: signal passes from sensor to control box through wire -Integrating center: control box is programmed to respond to temp below 29 dec -Output signal: signal passes through wire to heater -Target: heater turns on -Response: water temp increases
Define homeostasis
-The body is continuously working within a range of healthy states. AKA steady state equilibrium -Maintaining the dynamic steady states of the body's compartments
Positive feedback loop
-The response reinforces the stimulus, sending the variable farther from the set point (and homeostasis). An outside factor is required to shut off the positive feedback cycle
-Mass flow -Law of mass balance
-Used to determine rate of intake,output, or production -If an amount of substance is to remain constant, any gain must be offset by an equal loss
Key concepts in physiology
1. Homeostasis and control systems 2. Biological energy use 3. Structure/function relationships 4. Communication
Levels of organization
Atoms - molecules - cells - tissues - organs - organ systems - organisms - populations of one species - ecosystem of different species - biosphere
What are molecular interactions?
Attractive or repulsive noncovalent forces between molecules and non-bonded atoms
Describe the distribution of ions in ECF and ICF
ECF: high in Na+, Cl-/ low in K+ ICF: high in K+. low in Na+, Cl-
Information flow
Flows cell to cell through chemical and/or electrical signals
What does the integrating center do?
Give instructions of what to do based on the input signal. If system if out of homeostasis, it will make a response to negate the signal
Meaning of: homeo- -stasis
Homeo = like/similar Stasis = condition
Where is most of our body fluid concentrated?
ICF, 1/4 of it being in blood
What is a feedback loop?
Info about the homeostatic response is sent back to integrating center
Describe the flow of info through a homeostatic control system that explains regulation
Input signal -> integrating center -> output signal -> response to restore homeostasis
External or internal change that affects homeostasis results in
Loss of homeostasis, and thus, compensation
Define normal range of function
Maximum and minimum values around the set point that is still considered normal
Negative feedback loop
The response counteracts the stimulus, shutting off the response loop, and the system returns back to homeostasis
