Hormones & Homeostasis Flashcards
Endocrine System
ductless system that happens through blood and is the mechanism for hormone transport
Characteristics of the Endocrine System
- Ductless
- Occurs in blood stream
- Hormones + hormone shapes are highly specific to a target cell
- Does not have exocrine glands
Exocrine glands
glands that have ducts and release substances out (ie. mammary glands, sweat glands, sebaceous glands)–NOT part of the endocrine system
Which hormones does the posterior pituitary control?
ADH (vasopressin) and oxytocin
Neurohypophosis
The pathway from the hypothalamus to the posterior pituitary, where hormones ADH and oxytocin are made and then sent out to the rest of the body
Function of ADH
Anti-diuretic hormone– causes you to retain water. Released when solute concentrations in the blood are high and signals to the kidneys to open up the aquaporins and let water out of the collecting duct and into surrounding tissue
Why does caffeine cause dehydration?
Because caffeine is a competitive inhibitor for ADH and prevents it from opening up aquaporins
Which receptors detect blood solute concentration?
Osmoreceptors in the hypothalamus
What does the anterior pituitary gland control?
Most other hormones besides oxytoxin + ADH, sends hormones that signal to other glands
Hypothalamus
Area of the brain that acts as the control center for hormones, sends signals for the pituitary gland to signal to other secondary glands
Homeostasis
the tendency of an organism to maintain a constant internal environment (eg. constant levels of pH or O2)
Negative feedback loop
Reaction where the output regulates the production of the output. Basically, the more the output, the more the process is reduced
Found in homeostasis and processes like temperature and glucose regulation
Cooling Mechanisms
- Vasodilation- Capillaries dilate, so blood flow is slower and more heat can be released + capillaries move closer to surface of skin, makes it easier to liberate heat
- Sweating- evaporative cooling
Warming Mechanisms
- Vasoconstriction- skin arterioles contract, and capillaries move away from surface so less heat is lost
- Shivering- muscles shake in small movements, which uses up ATP and then the reaction releases heat as byproduct.
- Piloerection (goosebumps)- traps pockets of heat close to body surface and closes off any holes in skin
- Behavioral responses- ie. burrowing, putting on clothes, bathing in hot springs, etc
Positive Feedback Loops
When the product of a reaction leads to an increase in the reaction
Examples of Positive Feedback Loops
- Oxytocin in labor and contraction
- Blood clotting- when clotting factors are released, it signals for more platelets to join, and those platelets release clotting factors, so the more platelets, the more clotting factors are released and the reaction keeps building
What do B-islet cells produce?
Insulin
What do A-islet cells produce?
Glucagon