Chapter 1 - Homeostasis

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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


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