Chapter 01 Homeostasis: A framework for Human Physiology Flashcards
(69 cards)
What is homeostasis?
Homeostasis
Most of the common physiological variables of the body are maintained within a ______ range
predictable
Is homeostasis a static or dynamic process?
Dynamic process, not static.
values aimed to be kept at a constant range.
‘set point’
Physiological variables can change dramatically over a 24-hr. Period, but the system is still in overall balance
true
What is an example of a physiological variable maintained by homeostasis?
Body temperature (36.5 - 37.8)
blood pressure
Heart rate
Blood sugar level
Platelet count
Oxygen and CO2 levels in the blood
Resting metabolic rate
Na and K concentration
Other examples include blood pressure, heart rate, blood sugar level, and oxygen levels.
Homeostasis is maintained
through a complex system of feedback loops, primarily negative feedback loops, where the body constantly monitors internal conditions and adjusts them to keep vital parameters
Physiology
Homeostasis is not maintained, which can result in various physiological disruptions
Pathophysiology
High body temperature is maintained by
sweating
Heart rate, normal and abnormal
(55 - 100 bpm, < bradycardia, > tachycardia)
Blood sugar level, normal and abnormal
(~ 70 - 100 mg/dL, < hypoglycemic, > hyperglycemic)
Example of dynamic constancy
Blood glucose levels increase after eating
Levels return to their set point via homeostasis
Levels change over short periods of time, but remain relatively constant over long periods of time
maintains body temperature when room temperature increases
Homeostatic control system
What happens to blood glucose levels after eating?
Blood glucose levels increase after eating and return to their set point via homeostasis.
Feed forward
Enhances the production of the product and usually indicates possible illness.
Positive feedback system
example Positive feedback system
Continuous increase of oxytocin during childbirth
Thyroid storm
Give an example of a positive feedback system.
Continuous increase of oxytocin during childbirth.
Another example is a thyroid storm.
Shuts the system off once the set point has been reached.
Most of the important body feedback systems will be based in this
Negative feedback system
controls the sequence of chemical reactions by inhibiting the sequence’s rate-limiting enzyme, “Enzyme A.” inNegative feedback systems
“Active product”
Anticipates changes in regulated variables to improve the speed of the body’s homeostatic responses
Minimizes fluctuations in the level of the variable being regulated
possible illness, cannot be stopped
Feedforward Regulation
Feedforward Regulation examples
When outside temperature decreases, neurons detect the change and relay information to the brain
The smell of food triggers nerve responses from smell receptors in the nose to the cells of the digestive system
A specific involuntary, unpremeditated, unlearned “built-in” response to a particular stimulus
Reflex
The pathway mediating a reflex
Reflex arc
What are the components of a reflex arc?
Stimulus, receptor, afferent pathway, integrating center, and efferent pathway.