Homeostasis Flashcards
What is homeostasis?
relatively stable set of conditions within an organism’s internal environment
Why is the constancy of the internal environment important?
allows chemical reactions to take place at rates necessary to maintain the body.
What are the three important conditions that must be met to maintain a constant internal environment?
maintaining proper concentrations of gases, nutrients, water, and salts
What constitutes the internal environment of the human body?
extracellular fluid that surrounds cells, which are responsible for controlling bodily activities and the composition of this surrounding material.
What is a stressor?
causes an imbalance in the internal environment, potentially leading to illness or death.
What are examples of external and internal stressors?
External stressors include lack of environmental oxygen and extreme environmental temperatures. Internal stressors include rapid changes in blood pressure and changes in nutrient levels.
What is the role of feedback systems in maintaining homeostasis?
monitor internal conditions and react to deviations from homeostasis.
What are the basic components of a feedback system?
a sensor, a control center, an effector, and a response.
What is a negative feedback system?
reverses a deviation from the set point to maintain body parameters within their normal range.
Give an example of a negative feedback system in the body.
When body temperature rises, sensors send signals to the hypothalamus, which activates effectors to reduce temperature, such as dilating blood vessels and activating sweat glands.
What is a positive feedback system?
ntensifies a change in the body’s physiological condition rather than reversing it, moving the system farther away from the normal range.
Provide an example of a positive feedback system.
childbirth. Contractions push the baby toward the cervix, stretching it and triggering the release of oxytocin, which intensifies contractions until the baby is born.
How is blood glucose regulated by negative feedback?
beta cells in the pancreas release insulin, signaling cells to take up excess glucose
How does the body respond to increased temperature using a negative feedback system?
sensors send signals to the hypothalamus, which activates responses such as dilating skin blood vessels and activating sweat glands to release heat and lower body temperature.
How does the body respond to decreased temperature using a negative feedback system?
sensors send signals to the hypothalamus, which activates responses such as constricting skin blood vessels, triggering shivering, and increasing metabolic activity to generate heat and raise body temperature.
