Endocrine System Flashcards
Hormones
Endocrine signaling molecules that run directly into the blood stream, travel long distance to target tissues, where they bing to receptors and induce a change in gene expression or cell function
Peptide hormones
- Composed of amino acids
- polar cannot pass through the plasma membrane
- Bind to extracellular receptors where they affect levels of second messenger (cAMP) and initiates a cascade
Peptide hormones travel method
Dissolves and travels freely WITHOUT carriers
Peptide hormones rapidness of onset and duration of action
Quick onset and short lived
Steroid hormones
- Derived from cholesterol
- mostly non-polar and pass through plasma membrane
- binds to a receptor, induces conformational change and regulates transcription at the level of DNA
Steroid hormones travel method
Binds to a carrier protein
Steroid hormones rapidness of onset and duration of action
Slow and long lived
How are amino acid derivative hormones synthesized?
Made by modifying amino acids, such as the addition of iodine to tyrosine ( in thyroid hormone production)
Direct hormone
Are secreted into the bloodstream and travel to a target tissue, where they have direct effects.
- Major effects in non-endocrine tissues
Tropic Hormone
Cause secretion of another hormone that then travels to the target tissue to cause an effect
- Major effects in other endocrine tissues
What blood vessel system connects the hypothalamus with the anterior pituitary
Hypophyseal Portal System
Gonadotropin-releasing hormone (GnRH) from hypothalamus promotes the release of
Follicle stimulating hormone (FSH) and Luteinizing hormone (LH)
Target organ: Gonads (tested and overies)
Hormone released by target organ: Testosterone (testes) and estrogen/progesterone (ovaries)
Growth Hormone -releasing hormone (GHRH) from hypothalamus promotes the release of
Growth Hormone
Target organ: Bone, muscle
Hormone released by target organ: N/A
Thyroid- releasing Hormone (TRH) from hypothalamus promotes the release of
Thyroid- stimulating hormone (TSH)
Target Organ: Thyroid
Hormone released by target organ: Triiodothyronine (T3), Thyroxine (T4)
Corticotropin Releasing Factor (CRF) from hypothalamus promotes the release of
Adrenocorticotropic hormone (ACTH)
Target Organ: Adrenal Cortex
Hormone released by target organ: Glucocorticoids (Cortisol and cortisone)
Dopamine from hypothalamus promotes the release of
Prolactin
Target Organ: Breast Tissue
Hormone released by target organ: N/A
Prolactin Exception
As long as Hypothalamus releases PIF (dopamine), no prolactin is released. It is the absence of PIF that causes prolactin to be released
Interaction of the hypothalamus with the posterior pittuitary
Via the axons of nerves in the hypothalamus. Antidiuretic (ADH or vasopressin) and oxytocin are synthesized in the hypothalamus and then travel down these axons to the posterior pituitary, where they released into the bloodstream.
Anterior pituitary Products
FLAT PEG ( FLAT= tropic hormone and PEG= Direct Hormone)
Follicle stimulating hormone (FSH) Luteinizing hormone (LH) Adrenocorticotropic hormone (ACTH) Thyroid- stimulating hormone (TSH) Prolactin Endorphins Growth Hormone (GH)
Follicle stimulating hormone (FSH)
Source: Anterior Pituitary
Type: Peptide
Action: Stimulates the follicle maturation in females; spermatogenesis in males