hormone general info- endocrine objectives 1-4 Flashcards
What are hormones?
Chemical messengers that exert effects by attaching to receptor sites on target tissues.
What is the role of primary messengers?
They act directly by signaling target tissues to prepare for action, initiating signal transduction.
What analogy explains primary messengers?
Like the first friend in a game of telephone, passing the original message.
What is signal transduction?
A process like passing a baton in a relay race, where the signal continues until the task is completed.
What is the role of secondary messengers?
They amplify and spread the message from primary messengers to ensure effective communication.
What analogy explains secondary messengers?
Like a helper friend in telephone, making the message louder or spreading it around.
Why do hormones only affect certain cells?
Hormones bind only to cells with specific receptors, following the lock-and-key mechanism.
What triggers the release of hormones?
Changes in the cellular environment or the need to maintain levels of certain substances or other hormones.
Why is hormone production variable?
It responds to signals for need, such as producing more cortisol or aldosterone during stress.
How does a tumor affect hormone production?
It can vary secretion rates, leading to unpredictable hormone levels.
How are hormones regulated?
Through feedback systems, mostly negative feedback, with a few positive feedback loops.
What happens if hormones aren’t inactivated or excreted?
Hormone levels build up, causing dysfunction and imbalance.
How are hormones inactivated or removed from the body?
Inactivated by the liver or excreted directly by the kidneys.
What can happen with liver dysfunction?
Hormone levels increase, leading to problems like impaired clotting and detoxification.
What are the two main classifications of hormones?
Water-soluble hormones and lipid-soluble hormones.
How do water-soluble hormones circulate in the blood?
They circulate freely in the blood but require transport proteins for communication.
What is a key characteristic of water-soluble hormones regarding molecular weight?
They have a high molecular weight, preventing them from diffusing across the plasma membrane.
How do water-soluble hormones communicate their message?
They bind to receptors on the surface of target cells and communicate the message inward.
What are lipid-soluble hormones synthesized from?
They are synthesized from cholesterol.
How do lipid-soluble hormones diffuse through cell membranes?
They easily diffuse across the plasma membrane due to their lipid nature.
Where do lipid-soluble hormones bind once inside a cell?
They bind to intracellular receptors.
Do lipid-soluble hormones need help to communicate?
No, they can communicate by themselves without needing transport proteins.
What is the main difference in how water-soluble and lipid-soluble hormones transmit their messages?
Water-soluble hormones use surface receptors to send signals inward, while lipid-soluble hormones directly enter cells and bind to intracellular receptors.
What are target cells?
Specific cells that recognize and bind to hormones with high affinity to initiate a signal.
How does the number of receptors affect cell sensitivity?
The more receptors a cell has, the more sensitive it is to the hormone.
What is up-regulation?
A process where low concentrations of hormones lead to an increase in the number of receptors per cell.
Why does up-regulation occur?
To enhance the cell’s sensitivity and response to low levels of hormones.
What is down-regulation?
A process where high concentrations of hormones lead to a decrease in the number of receptors per cell.
When does down-regulation happen?
When a cell is overwhelmed by high hormone levels, resulting in decreased receptor numbers.
What effect does down-regulation have on the cell?
It decreases the cell’s sensitivity to the hormone, making it less responsive.
How can the analogy of a telephone game help understand target cells?
Target cells are like specific friends in a game of telephone who receive and respond to the message.
What mechanisms regulate hormone synthesis and secretion?
Specific mechanisms that can either stimulate or inhibit hormone production and release.
What is positive feedback in hormone regulation?
A mechanism where the response amplifies physiological changes rather than reversing them.
Give an example of positive feedback.
Oxytocin stimulates muscle contractions during childbirth; increased oxytocin leads to stronger contractions until delivery.
What is negative feedback in hormone regulation?
A mechanism where the response reverses or causes the opposite physiological effect of the original stimulus.
How is negative feedback similar to a thermostat?
It regulates hormone levels by maintaining them within a set range, adjusting production as needed.
Give an example of negative feedback related to calcium levels.
If blood calcium levels rise too much, the parathyroid glands reduce PTH production to lower calcium levels.
Give an example of negative feedback related to thyroid hormones.
Sufficient levels of thyroid hormone (T4) in the bloodstream decrease production of TSH and TRH by the anterior pituitary and hypothalamus.
What role does the nervous system play in hormone regulation?
The nervous system can control hormone secretion based on physiological rhythms, such as the daily light-dark cycle.
Provide an example of hormonal regulation influenced by physiological rhythms.
Melatonin secretion is regulated by the daily light-dark cycle, increasing at night and decreasing during the day.
