Introduction to Physiology Flashcards
Define physiology and explain its scope.
Physiology is the study of how the body functions, encompassing the physical and chemical processes within cells, tissues, organs, and organ systems. It explores how these components work individually and together to sustain life.
What is homeostasis, and why is it crucial for cell survival?
Homeostasis is the body’s ability to maintain relatively stable internal conditions despite changes in the external environment. It is crucial for cell survival because cells can only function within a narrow range of conditions, such as pH and temperature.
List five examples of conditions that are tightly controlled to maintain homeostasis.
Five examples of conditions controlled to maintain homeostasis include pH, temperature, blood gases (CO2, O2), blood pressure, and intracellular and extracellular fluid volumes.
Explain the role of the nervous and endocrine systems in maintaining homeostasis.
The nervous and endocrine systems act as control centers to maintain homeostasis by detecting changes and initiating responses to correct deviations. They achieve this by controlling the activity of other organ systems to keep conditions within physiological limits.
Differentiate between anticipatory responses and feedback mechanisms in regulating homeostasis. Provide an example of each.
Anticipatory responses prepare the body for a change before it occurs, such as increased respiratory rate at the start of exercise, driven by proprioceptors. Feedback mechanisms respond to changes that have already occurred, such as shivering in response to decreased body temperature.
Describe the three basic components of a feedback mechanism.
The three basic components of a feedback mechanism are receptors (which monitor variables), control centers (which integrate information and signal effectors), and effectors (which create a response to alter the variable).
Explain negative feedback, and provide an example of how it works to maintain a variable within its setpoint.
Negative feedback is a homeostatic control mechanism where the response counteracts the initial change, moving the variable back toward its setpoint. For example, if body temperature increases, the body initiates processes to reduce it, bringing it back within the normal range.
How does the body respond to increased body temperature using negative feedback?
When body temperature increases, receptors in the hypothalamus trigger effectors like blood vessels in the skin to dilate, increasing heat loss through radiation. Sweat glands also activate, causing evaporative cooling, both working to decrease body temperature.
Explain positive feedback, and why it is typically not considered homeostatic.
Positive feedback amplifies the initial change, pushing the variable further away from its setpoint. Therefore, it is not typically homeostatic. It creates a cycle of increasing response until an endpoint is reached.
Provide an example of positive feedback and describe its endpoint.
An example of positive feedback is childbirth, where uterine contractions stimulate the release of oxytocin, which further intensifies contractions. This continues until the endpoint is reached: the baby is born.
