homeostasis Flashcards
(15 cards)
What is homeostasis?
The control or stabilization of the internal environment.
What is physiology according to the OED?
The study of the normal function of living organisms.
What is the primary function of organ systems?
To maintain homeostasis.
Name the three main components of extracellular fluid (ECF).
Plasma, Interstitial fluid (ISF), Transcellular fluid.
What percentage of total body weight is water in a 70 kg man?
About 60%, which is ~42 liters.
What distinguishes regulators from conformers?
Regulators maintain internal stability; conformers adapt to external conditions.
What are the normal ranges for blood glucose and blood pH?
Glucose: 4–7 mmol/l; Blood pH: 7.3–7.5.
Give an example of illness caused by disruption of homeostasis.
Cholera: causes Cl⁻ secretion, osmotic imbalance, and dehydration.
What are the components of a negative feedback system?
Set point, sensor, comparator, and effector.
How does the body regulate blood pressure using negative feedback?
Sensors (baroreceptors) → Medulla comparator → Adjusts heart rate/vasoresponse via autonomic nervous system.
What hormone increases when plasma glucose exceeds 100 mg/100 ml?
Insulin.
What is an example of a positive feedback system?
Blood clot formation or oxytocin-induced uterine contractions during labor.
Why are most physiological systems negative feedback systems?
To maintain stability and avoid runaway conditions.
Which organ acts as the body’s thermostat?
The hypothalamus.
What is the result of hypoventilation on plasma CO₂ levels?
Increases plasma CO₂.
