Homeostasis Flashcards
(39 cards)
What is a feedback loop in homeostasis?
A system that maintains balance by detecting changes and triggering responses to restore stability.
What are the components of a feedback loop?
Stimulus → Sensor → Effector → Response
What is negative feedback?
A response that reverses a change (e.g. body temp regulation, blood sugar control).
What is positive feedback?
A response that amplifies a change (e.g. childbirth contractions, blood clotting).
Example of a negative feedback loop
If body temperature rises, the body sweats to cool down.
Example of a positive feedback loop
Oxytocin increases contractions during labor until birth.
What is thermoregulation?
Maintaining a stable internal body temperature.
How does blood help with thermoregulation?
Blood vessels dilate (vasodilation) to release heat and constrict (vasoconstriction) to retain heat.
Example of negative feedback in thermoregulation
If the body gets too hot, sweating and vasodilation occur to cool it down.
What is the main function of the excretory system?
To remove waste (like urea) and regulate water and salt balance.
What is a nephron?
The functional unit of the kidney where urine is formed.
Steps of urine formation in the nephron?
Filtration → Reabsorption → Secretion → Excretion
Where does filtration occur in the nephron?
In the glomerulus (inside Bowman’s capsule).
What is reabsorbed back into the blood in the nephron?
Glucose, water, and some salts in the proximal tubule and loop of Henle.
What does the collecting duct do?
Final site of water reabsorption; sends urine to the ureter.
What are hormones?
Chemical messengers that travel in the blood to target organs.
How do hormones work?
They bind to specific receptors on or in target cells to trigger a response.
What is the master gland of the endocrine system?
The pituitary gland – it controls other glands and releases many hormones.
What hormone is released during short-term stress?
Adrenaline (epinephrine) from the adrenal medulla (fight or flight).
What hormones are released during long-term stress?
Cortisol and aldosterone from the adrenal cortex (regulate metabolism and water balance).
What’s the connection between the nervous and endocrine systems?
The hypothalamus links them by controlling the pituitary gland.
What does the pancreas release to regulate blood sugar?
Insulin (lowers blood sugar) and glucagon (raises blood sugar).
What gland controls metabolism?
The thyroid – releases thyroxine to regulate metabolic rate.
What are the two main parts of the nervous system?
Central Nervous System (CNS) and Peripheral Nervous System (PNS)
