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Questions and Answers
What effect does positive feedback have on physiological responses?
What effect does positive feedback have on physiological responses?
Which glands are considered part of the coordination of endocrine and nervous systems in vertebrates?
Which glands are considered part of the coordination of endocrine and nervous systems in vertebrates?
What hormone is primarily involved in milk production and mammary gland growth in mammals?
What hormone is primarily involved in milk production and mammary gland growth in mammals?
In insects, what role does juvenile hormone play?
In insects, what role does juvenile hormone play?
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What stimulates the secretion of hormones by endocrine glands?
What stimulates the secretion of hormones by endocrine glands?
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Which class of hormones is water soluble?
Which class of hormones is water soluble?
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What is the primary function of the endocrine system?
What is the primary function of the endocrine system?
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How do lipid soluble hormones enter target cells?
How do lipid soluble hormones enter target cells?
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What role do pheromones play in the endocrine system?
What role do pheromones play in the endocrine system?
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What do positive feedback mechanisms in hormone secretion generally indicate?
What do positive feedback mechanisms in hormone secretion generally indicate?
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Which organ is considered the primary link between the endocrine and nervous systems?
Which organ is considered the primary link between the endocrine and nervous systems?
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What distinguishes endocrine glands from exocrine glands?
What distinguishes endocrine glands from exocrine glands?
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Which of the following is NOT a function of the hypothalamus in the endocrine system?
Which of the following is NOT a function of the hypothalamus in the endocrine system?
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Study Notes
Endocrine System Overview
- The endocrine system is responsible for producing and regulating hormones.
- Hormones are chemical messengers transported through the blood.
- Hormones trigger responses in target cells.
Hormone Classes
- Three main chemical classes:
- Polypeptides (e.g., insulin): water-soluble
- Amines (e.g., thyroxine, epinephrine): water-soluble
- Steroids (e.g., cortisol): lipid-soluble
Hormone Solubility and Action
- Water-soluble hormones cannot diffuse through plasma membranes.
- Bind to cell-surface receptors.
- Induce changes in cytoplasmic molecules.
- May alter gene transcription.
- Lipid-soluble hormones diffuse across membranes.
- Bind to receptors in the cytoplasm or nucleus.
- Trigger gene transcription changes.
Hormone Secretion Control
- Feedback mechanisms regulate hormone secretion.
- Negative feedback: maintains a stable internal environment.
- Positive feedback: amplifies a response (e.g., oxytocin during childbirth).
Endocrine Glands
- Endocrine glands secrete hormones directly into the bloodstream.
- Examples: pituitary, thyroid, adrenal, pancreas, ovaries, testes.
- Exocrine glands have ducts (e.g., salivary glands).
- Hormones can be produced in organs other than glands, for example: stomach, brain, and kidneys.
Hormone Action Example
- Bayliss and Starling (1902): Secretin and CCK in the digestive system.
- Secretin regulates bicarbonate release.
- CCK regulates digestive enzyme release.
Animal Responses to Cues
- Animals respond to cues from their environment (environmental), behavior (behavioral) and their physical state (physiological).
- Examples: birds building nests, territory singing, day length.
- Organisms have signaling molecules which are not produced within the body – pheromones.
- Frog life cycle – the endocrine system controls the development stages.
Neuroendocrine System
- The endocrine and nervous systems work together to maintain homeostasis.
- The hypothalamus is a key link between these systems, releasing hormones that stimulate or inhibit the pituitary gland.
- The pituitary gland (anterior and posterior) releases hormones influencing various bodily functions.
Hormone Cascade Pathways
- Hypothalamus releases hormones that influence the anterior pituitary.
- Anterior pituitary hormones influence target endocrine glands.
- Target glands release hormones to target tissues, triggering responses.
- Example of this Cascade: Prolactin from the anterior pituitary.
Factors Stimulating Endocrine Glands
- Blood concentrations of non-hormone chemicals
- Other hormones
- Neural stimuli
Evolution of Hormone Function
- The same hormones can have different functions depending on the organism.
- Example: prolactin's role in mammals (milk production), birds (fat metabolism, and parental care), amphibians (metamorphosis delay), and fish (salt/water balance).
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Description
Explore the complexities of the endocrine system and its hormone classes in this quiz. Learn about hormone solubility, action mechanisms, and the feedback regulations that maintain balance in the body's internal environment. Test your knowledge on how these chemical messengers influence various physiological responses.
