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Flashcards in Intro Deck (34):

The endocrine system Coordinates hormone signaling pathways that regulate: ?

1. Metabolism
2. Growth & development
3. Water & electrolyte balance


What other system does the endocrine system work closely with?

Nervous system


Compare the endocrine and nervous systems

1. Endocrine System
A. Secretes hormones that travel through bloodstream
B. Action relatively slow
C. Effects are prolonged
D. More general effetcs
2. Nervous System
A. Electrochemical impulses via neurons
with neurotransmitters
B. Rapid response
C. Effects are brief and specific


What does the heart secrete?

Important in sodium and water balance


What does the kidney secrete?

Secretes erythropoietin
Hormone essential for production of red blood cells


Define hormones

1. Chemical substances that regulate activity of certain cells
2. Hormones react with specific receptors
3. Organs, tissues, or cells lacking the specific receptor do not respond to its stimulating effects


How are hormones secreted? What are the characteristics of each method?

A. Diffusion
1. Continuous release
2. Steroid hormones
B. Pulsatile
1. Peak & ebb relative to:
-Circadian rhythm
-Response to meals
-Hormone releasing factors


What is the action of a hormone?

1. Once secreted by endocrine organs, hormones travel to their target tissue
A. Bind to specific receptors
B. Initiate chain of events
-Physiologic effects of hormone


Which type of glands have ducts?



Which type of glands do not have ducts?



How are hormones transported?

1. Circulate bound to carrier proteins or free
A. Free = active hormone
B. Bound = reservoir to prolong half life


What are circulating levels of hormones regulated by?

1. Rate of secretion
2. Nature of secretion
3. Hormone degradation and/or uptake
4. Receptor binding
5. Receptor availability
6. Affinity of hormones for plasma carriers


What is the action and source of thyroid hormone?

1. Thyroid
2. Controls basal metabolism


What is the action and source of cortisol?

1. Adrenal cortex
2. Energy metabolism; basis for sex hormones


What is the action and source of mineralcorticoids?

1. Adrenal cortex
2. Regulates plasma volume via effects on serum electrolytes


What is the action and source of vasopressin?

1. Post pit
2. Regulates plasma osmolality via effects on water excretion


What is the action and source of PTH?

1. Parathyroid glands
2. Regulates Ca & PO4


What is the action and source of insulin?

1. Pancreas
2. Regulates glucose concentration


What are the classes of hormones?

1. Peptides
2. Steroids
3. Biogenic amines


What are the characteristics of peptide hormones?

1. Formed from chains of amino acids
2. Longer chains are called protein hormones
3. Example: growth hormone


What are the characteristics of steroid hormones?

1. Type of lipid derived from cholesterol
2. Example: aldosterone, testosterone


What are the characteristics of biogenic amines?

1. Small molecules produced by altering the structure of tyrosine
2. Example: thyroid hormone


Where are cell surface hormone receptors located?

Cell membrane


What are the classes of hormones that bind to cell surface receptors?

Proteins and Amines


What is the moa of protein and amine hormone/receptor binding?

1. Hormone binds to receptor (first messenger); stimulates chemical response via a second messenger
2. Second messengers alter activity of enzymes within the cell
3. Receptor binding increases adenylate cycalse activity -> ATP converted to cyclic AMP -> stimulates changes in cell processes (activate enzymes, alter cell membrane permeability, stimulates protein synthesis, stimulates secretion)


Where are intracellular hormone receptors located?

Located in cytoplasm or nucleus


What are the classes of hormones that bind to intercellular receptors?

Steroid and thyroid hormones


What is the moa of steroid and thyroid hormone/receptor binding?

1. Alters transcriptional activity of genes
2. Causes synthesis of proteins in target cells via translation


define negative feedback regulation

1. Responsiveness of target cells to hormonal action -> Feeds back to control secretion

2. Inhibition of initial hormone release mechanism


define positive feedback regulation

Continued stimulation of the original hormone release mechanism
ex. Prolactin and oxytocin


What is the function of the hypothalamus?

1. Secretes regulatory hormones that control endocrine cells in anterior pituitary gland
2. Synthesizes & releases hormones from posterior pituitary gland. Hormones affect adrenal, thyroid, and gonadal glands


What can hormone deficiency result from? What are some examples?

1. Results from destruction of glandular structure
A. Hashimoto’s thyroiditis
B. Diabetes mellitus Type I


What can hormone resistance result from? What is an example?

1. Adequate levels of hormone synthesized and released
2. Target tissues are resistant to hormone’s effects
A. Diabetes Mellitus Type II


What can hormone excess result from? What is an example?

1. Hormones produced in excessive and uncontrollable manner
A. Acromegaly or gigantism
B. Graves Disease