Homeostasis
What is homeostasis?
Homeostasis is the process by which the body maintains a stable internal environment despite changes in external conditions.
What is leptin?
A hormone that regulates body weight, energy, hunger, and influences metabolism (because of tolerance).
Leptin release signals to the brain that you're full
What's ghrelin?
Ghrelin keeps the body fed. Released when the stomach is empty, ghrelin activates hunger circuits in the hypothalamus that drive a search for food. Once the stomach is full, ghrelin production stops, reducing the desire to eat
What's the difference between the parasympathetic and sympathetic nervous systems in terms of their functions?
Sympathetic Nervous System: "fight or flight" system, prepares the body for stressful or emergency situations. When active it increases heart rate, dilates the airways, redirects blood flow to muscles, and releases stress hormones like adrenaline
Parasympathetic Nervous System: "rest and digest" system. It decreases heart rate, constricts the airways, increases blood flow to the digestive system, and stimulates functions such as digestion and nutrient absorption
T/F: Clock proteins take exactly 24 hours to complete a full cycle
False. They take slightly more than 24 hours but factors like the light-dark cycle helps reset them.
What's the difference between neuronal and hormonal communication?
Neurons communicate through rapid electrical impulses transmitted across tiny gaps called synapses to precise targets in the body
Hormones deliver messengers released into the bloodstream by endocrine glands, traveling to distant target cells to trigger slower, longer-lasting physiological responses throughout the body (large-scale effects)
Is the anterior or posterior pituitary involved in the release of growth hormone?
Anterior pituitary
T/F Ghrelin is primarily secreted by the pituitary gland
(Bonus: what produces leptin?)
False! Ghrelin is primarily secreted by the stomach, not the pituitary gland
Leptin is primarily produced by fat cells (adipose tissue)
During times of stress, what hormones are released and what are their effects?
Epinephrine (aka adrenaline) and norepinephrine trigger the activation of the sympathetic nervous system ("flight" or "fight") -- increasing heart rate, blood pressure, etc
Glucocorticoids (like cortisol) increase blood sugar for quick source of energy and enhance brain function
The pineal gland secretes what hormone?
Melatonin (which rises at night to facilitate sleep)
What are some examples of physiological processes that illustrate homeostatic regulation?
Thermoregulation, Blood glucose regulation, Fluid balance, pH balance
Why is vasopressin called the "antidiuretic" hormone?
It helps regulate water balance in the body. It promotes water retention in the kidneys, helping to decrease urine output and conserve water, which is essential for maintaining proper fluid balance and preventing dehydration.
T/F. Hormones produced by the pituitary glands do not alter gene transcription in the hypothalamus
False! Many often bind to receptors within the hypothalamus and influence neuronal function, affecting gene expression levels
What are some long-term effects of chronic stress on the autonomic nervous system and overall health?
Chronic stress can increase risk of heart attacks, reduce resistance to infection and inflammation, inhibit growth, and impair the normal processes of memory formation and recall, muscle atrophy, push body to store energy as fat, keep blood sugar and pressure abnormally high, and can lead to sleep disorders.
What produces cortisol?
While the hypothalamus and pituitary gland signal cortisol production, cortisol itself is produced by the adrenal glands (which sit on top of the kidneys)
What's a negative feedback loop, and how does it contribute to the maintenance of homeostasis? (BONUS: give an example)
Negative feedback loops: Reduce the output of a system when a set point is reached (a system that uses its output to regulate itself)
Positive feedback loops: These amplify responses or processes in the body. A circular chain of events that causes a system to move further away from equilibrium by increasing its output.
What is oxytocin and its primary effects?
Oxytocin (aka the "love hormone") is involved stimulating contractions during childbirth, facilitating the release of milk during nursing, social bonding, trust, and emotional connections
What's the difference between trophic and non-tropic hormones?
How is cortisol produced? (hint: start at the hypothalamus)
Corticotrophin releasing hormone (CRH) is released from the hypothalamus and travels to the pituitary gland, where it triggers the release of adrenocorticotropic hormone (ACTH). ACTH travels in the blood to the adrenal glands, where it stimulates the release of cortisol.
When do natural cortisol levels peak?
Levels of stress hormone cortisol peak early morning (7-9 am) in the blood which increases appetite, core body temperature begins to ship upward