Chapter 1 Into To Physiology Flashcards
What is Physiology?
In the simplest terms:
-Study of the normal functioning of a living organism and its component parts
How does the body, organs or tissues operate?
They operate via mechanisms.
How are the mechanisms of the body determined?
Determined from experimental evidence or pathophysiology.
What is used to validate a mechanism of the body, organ, or tissue?
Scientists use progressive steps in order to test the validity of a hypothetical mechanism called hypothesis testing
What are the steps of Hypothesis Testing?
Observe a phenomenon
Formulate a hypothesis
Test the hypothesis (experimentally)
Analyze the results —> Does the results negate or support the hypothesis
Why do we use the scientific method to validate mechanisms?
We can describe physiologic processes based on laws governing chemistry, biology and physics.
What are the two groups that are used to test hypotheses?
Control group
Experimental group
Who or what is the control group in an experiment?
Not subject to challenge/testing condition.
-usually given a placebo.
What defines the experimental group of an experiment?
They ARE subject to challenge/testing condition
-this is the group where a variable is changed. e.g. They are given the specific drug that is being tested.
Their response is compared to the control.
What causes variability in the samples during experiments?
There are always differences between the subjects this is referred to as variance
How do you limit the effects of variance during an experiments?
Sampling of large populations limits the effects of variance
What is the purpose of testing a mechanism or system?
Once we impose a “challenge” upon a biological system, we can then observe how the system or mechanism responds
What is the independent variable in an experiment
It’s the variable that is being changed and its graphed on the x-axis.
What is the Dependent Variable?
Variable being measured as it changes in response to the challenge
-Graphed on the Y-axis
What is the importance of Physiology Research?
Basic (primary) research provides us an understanding of physiology processes.
-from an intellectual standpoint, all research contributes to our basic Knowledge
We also preform physiology research because or what? And what is the term for this?
Clinical importance
-termed Translational Research
What are the two models used in Translational research
-in vivo, and in vitro
What is considered “in vivo” research?
Uses whole animal models. Usually does not include human models but it can
What is considered ‘in vitro” research?
Uses tissue, cell cultures. More recently uses computer models
What is Homeostasis?
It’s the maintenance of the relative constancy of the internal environment
Particular parameters are monitored and regulated
Maintained with a narrow range called a “set point”
What is referred to as the internal environment during Homeostasis?
Extracellular fluid (plasma + interstitial fluid)
What are some of the Homeostatically Regulated variables?
Arterial pH Bicarbonate Sodium Calcium Oxygen content Urea Amino acids Totally Lipids Glucose
Define Negative Feedback Loop
A homeostatic feedback loop designed to keep the system at or near a set point.
Serve to maintain Homeostasis
It’s a response that counteracts a disturbance in the system.
What are the components of a negative feedback loop?
A stimulus causes a disturbance—> sensor picks up the change—> input signal travels via the afferent pathway to—> integrating center—> output signal travels via the efferent pathway—>target or effector—> a response takes place
When the disturbance has been altered back within the homeostatic set point the negative feedback loop shuts of the response
Give an example of a negative feedback loop
Lying down to standing up fast cause the blood pressure to drop (stimulus)—>blood pressure receptors pick up on this change, they are the (Sensors) —>sensor sends input signal via the afferent pathway to the Integrating center —> output signal via the Efferent pathway signals the heart to increase its rate, which results in a rise in blood pressure.
The negative feedback pathway stops when the blood pressure has come back within the set range.
What is Antagonistic Control?
Some homeostatic parameters are maintained by two or more regulators with OPPOSING effects.
E.g. Blood glucose can go up or down having different effects which will cause the body to either raise insulin or decrease insulin causing an increase or decrease to blood glucose.
Is a positive feedback loop homeostatic?
No a positive feedback loop is not homeostatic. The response reinforces the stimulus rather than decreasing or removing it.
Give an example of a positive feedback loop is?
It involves the hormone control of uterine contractions during childbirth.
When the baby is ready to be delivered, it drops lower in the uterus and it begins to put pressure on the cervix. The pressure on the cervix send the signal via afferent pathway to the brain to cause the release of oxytocin, which causes the uterus to contract and push the baby out.
Not until this stretch from the cervix stops, after the deliver of the baby, the brain will not shut off the oxytocin. Once the stretch is gone the positive feedback loop will then stop
When will a positive feedback loop stop?
Only when the stimulus is removed or an outside source intervenes
