Topic 1: Endocrine System Flashcards
(56 cards)
What is the primary function of the endocrine system?
To regulate body processes through the release of hormones and maintain homeostasis.
How do hormones maintain homeostasis?
By using chemical messengers (hormones) to communicate between cells, triggering changes that regulate body functions.
What are the two main classifications of hormones?
Lipid-soluble hormones (steroids, thyroid hormones) and water-soluble hormones (peptides, catecholamines).
What type of receptor do lipid-soluble hormones bind to?
Intracellular receptors, often within the cytoplasm or nucleus.
What type of receptor do water-soluble hormones bind to?
Extracellular receptors on the cell membrane.
What is the signal transduction mechanism for water-soluble hormones?
Uses second messenger systems like cAMP or IP3/DAG to relay signals inside the cell.
What is the signal transduction mechanism for lipid-soluble hormones?
Directly affects gene transcription and protein synthesis after binding to intracellular receptors.
What is the hypothalamic-hypophyseal portal system?
A network of blood vessels connecting the hypothalamus to the anterior pituitary, allowing for direct hormonal communication.
Name a hormone secreted by the thyroid gland and its primary function.
Thyroxine (T4); regulates metabolism.
What hormone does the pancreas secrete to lower blood glucose levels?
Insulin.
Describe the three stages of the general adaptation syndrome (GAS).
- Alarm phase: Immediate fight-or-flight response. 2. Resistance phase: Hormonal support to sustain stress response. 3. Exhaustion phase: Resource depletion, risk of illness.
What is an example of a primary endocrine disorder?
Adrenal tumor causing excessive cortisol production (Cushing’s syndrome).
How does a secondary endocrine disorder differ from a primary disorder?
It involves the pituitary gland failing to properly stimulate the target endocrine gland.
What defines a tertiary endocrine disorder?
It involves dysfunction at the level of the hypothalamus, affecting downstream hormonal regulation.
What is the role of negative feedback in hormone regulation?
It prevents overproduction of hormones by reducing hormone secretion once the desired effect is achieved.
General Concepts: Endocrine System Overview
What is an endocrine gland?
Hint for remembering: Compare endocrine with exocrine—one uses blood vessels, the other uses ducts.
An endocrine gland is a ductless gland that produces and secretes hormones directly into the bloodstream, where they travel to target tissues to regulate various physiological functions.
Memory aid: Endo = inside (into the blood); Exo = exit (through ducts to the outside).
General Concepts: Endocrine System Overview
Where can endocrine glands be located in the body?
Endocrine glands can be located throughout the body, including the brain (hypothalamus, pituitary), neck (thyroid, parathyroid), chest (thymus), abdomen (pancreas, adrenal glands), and reproductive organs (ovaries, testes).
Many organs outside the endocrine system also release hormones!
Grouping by body region can help: head/neck, thorax, abdomen, pelvis.
General Concepts: Endocrine System Overview
What is the primary type of tissue that makes up endocrine glands?
Endocrine glands are primarily made up of epithelial tissue, specifically glandular epithelium specialized for hormone production and secretion.
Epithelial tissue forms linings and coverings, including the secretory portions of glands.
General Concepts: Endocrine System Overview
What do endocrine glands do?
Endocrine glands produce and secrete hormones into the bloodstream to regulate various physiological activities and maintain homeostasis.
Key role: long-distance signaling through hormones.
Mechanisms of Hormone Action
How do hormones affect other tissues?
Remember: the hormone alone isn’t enough—it needs something on the target tissue to work.
Hormones affect other tissues by binding to specific receptors on or inside target cells, triggering signal transduction pathways that result in cellular changes.
The receptor is the key to the hormone’s effectiveness.
Mechanisms of Hormone Action
What must occur at the target tissue for a hormone’s activity to be carried out?
Picture the hormone-receptor interaction like a handshake—it requires both participants.
The target tissue must have specific receptors for the hormone. Hormone binding to these receptors initiates a signaling pathway that leads to the hormone’s intended action.
“Lock and key” analogy: hormone = key, receptor = lock.
Hormonal Regulation
How does the hypothalamus know when to secrete one of its hormones?
Think about the body’s internal monitoring systems—how do they report conditions?
The hypothalamus monitors internal conditions through neural signals and feedback loops, particularly negative feedback from circulating hormone levels, as well as sensory input such as temperature and osmolarity.
Negative feedback helps maintain balance by adjusting hormone release based on current levels.
Hypothalamus Hormones
What is the function of Growth Hormone Releasing Hormone (GHRH)?
Growth Hormone Releasing Hormone (GHRH) stimulates the anterior pituitary to release growth hormone (GH).
GHRH → GH production.
Hypothalamus Hormones
What is the function of Growth Hormone Inhibiting Hormone (GHIH, somatostatin)?
Growth Hormone Inhibiting Hormone (GHIH), also known as somatostatin, inhibits the release of growth hormone (GH) from the anterior pituitary.
GHIH → blocks GH release.
