Chapter 17 - Endocrine System Flashcards
Hormones are…
Chemical messengers secreted into blood or ECF by one cell that affects the functioning of another cell that has a receptor for that hormone.
Most hormones circulate in ________.
Blood
Hormones affect a ______ # of cells
Limited
Hormone receptors are found ___________________ or ____________.
Exposed on the surface of a cell; within a cell
What are the major endocrine glands? (There are 10)
- Hypothalamus
- Pituitary gland
- Pineal gland
- Thyroid
- Parathyroid
- Adrenal gland
- Pancreas
- Testes
- Ovaries
- Placenta
What are 4 body tissues that double as endocrine glands?
- Gastrointestinal tract
- Placenta
- Kidneys
- Heart
How does negative feedback control endocrine activity? Is it common or rare?
Final hormone inhibits the release of the hormone which initiated the cascade of hormones.
Common.
How does positive feedback control endocrine activity? Is it common or rare?
Feedback loops are used to regulate the secretion of hormones in the Hypothalamic-Pituitary-Axis.
Rare.
What is an example of negative feedback in endocrine activity?
Thyroid hormone inhibits the hypothalamus
What is an example of positive feedback in endocrine activity?
Oxytocin released during labor
An increase in the # of receptors is called ________.
Up-regulation
A decrease in the # of receptors is called __________.
Down-regulation
The more receptors a hormone binds to, the _________ the response.
Greater
What is the difference between hormones and prostaglandins?
Hormones are produced in glands and affect organs all over the body; Prostaglandins are produced in tissues and affect neighboring cells
What are the advantages and disadvantages associated with the use of hormones to control physiology, instead of the nervous system?
Advantages:
- Hormones circulate throughout the body (not specific to one area)
- Hormones have a lasting effect (days or longer)
Disadvantages:
-Hormones take longer to have an effect (have to circulate through blood first, then bind to hormone receptor on target cell)
What household chemical mediates the effects of prostaglandin blood clot formation?
Aspirin (blocks the enzyme cyclooxygenase, which produces prostaglandins)
What biological macromolecule gives rise to steroid hormones?
Lipids
What biological macromolecule gives rise to non-steroid hormones?
Protein (Polypeptides)
What kind of receptors do steroid hormones bind to?
Steroid hormones bind to transcriptional factors inside the cell membrane (in the cytoplasm or the nucleus). The hormone-receptor complex binds to promoter regions, which turns on transcription of a specific genes + changes physiology.
3 domains of non-steroid hormone receptors:
- Extracellular domain (in ECF)
- Transmembrane domain (hydrophobic stretches of amino acids–stay with fatty acid tails inside the phospholipid bilayer)
- Intracellular domain (in ICF)
Hormones are secreted in a _______ fashion. What is an example of this?
Pulsatile.
Ex: Luteinizing hormone is secreted in pulses during ovulation
How are hormonal secretions of the Hypothalamic/Pituitary Axis controlled?
Negative Feedback:
-Common
-final hormone inhibits the release of the hormone which initiated the cascade of hormones
Ex: thyroid hormone inhibits TRH and TSH
Positive Feedback:
-Rare
-feedback loops regulate secretion of hormones
Ex: oxytocin released during labor by posterior pituitary gland to increase rate of contraction
How does the body reduce the metabolic effect of a hormone?
Through down-regulation (decreasing the # of receptors to decrease the effect of a hormone)
Hormones alter _________ processes.
Metabolic
What two hormones work together in providing milk for an infant?
Prolactin (produces milk due to suckling) - secreted by Anterior Pituitary
Oxytocin (ejects milk due to suckling) - secreted by Posterior Pituitary
What two hormones control blood Ca++ ion concentration? Which increases Ca++ levels, and which decreases Ca++ levels?
Calcitonin (secreted by extrafollicular thyroid cells)
- decreases blood Ca++ levels
Parathyroid (secreted by parathyroid glands)
+ increases blood Ca++ levels
What two hormones control blood sugar concentration? What organ are they secreted by, and by what types of cells?
Glucagon (secreted by Alpha cells in pancreas)
+ raises blood sugar
–> breaks down glycogen in liver into glucose
Insulin (secreted by Beta cells in pancreas)
- lowers blood sugar
- –> stimulate the synthesis of glycogen to store glucose in liver
- –> increases cell permeability to glucose
What hormone is produced by the follicular cells in the thyroid? Where are they stored?
Thyroxine (T4) is stored in colloid inside thyroid follicles
What elemental atom is represent by the 3 and 4 in T3 (Triiodothyronine) and T4 (Thyroxine)?
Iodine (which binds with Tyrosine protein)
What physiological effect does T3 hormone produce?
Increases metabolism by using ATP (which increases heat production)
What hormones are produced by the the extrafollicular thyroid cells?
Calcitonin
What other endocrine gland is embedded in the thyroid?
Parathyroid gland
What hormone has the effect of producing cellular growth? Where is it secreted?
Growth hormone (GH) - secreted by the anterior pituitary
What hormone inhibits the production of growth hormone (GH)? Where is it secreted?
Somatostatin (Growth hormone - inhibiting hormone / GHIH) - secreted by the pancreas by Delta cells
What two hormones affect kidney tubules? Where are they secreted?
Anti-diuretic hormone - secreted by the posterior pituitary
–> causes water retention in kidneys in response to dehydration
Aldosterone (a Mineralcorticoid) - secreted by the Adrenal Cortex
- –> causes reabsorption of Na+ and H2O
- —> increased secretion of K+
What are the three categories of hormones produced by the Adrenal Cortex? Give an example of each.
- Mineralcorticoids (Aldosterone)
- Glucocorticoids (Cortisol)
- Gonadocorticoids (Testosterone & Estrogen)
What hormones are produced by the Adrenal Medulla? What mechanism causes their secretion?
Epinephrine and norepinephrine.
- FIGHT OR FLIGHT mechanism causes their secretion
What are some effects of epinephrine and norepinephrine?
- Increased heart rate
- Increased metabolism
- Lipolysis (fat burning)
- Dilation of pupils
- Inhibition of non-essential processes (digestion)
What three hormones are produced by the pancreas? What cell type produces each?
- Glucagon (Alpha cells)
- Insulin (Beta cells)
- Somatostatin (Delta cells)
What endocrine glands / organs produces testosterone and estrogen?
Testes & Ovaries
What hormone is secreted in response to long term stress? Where is it secreted?
Cortisol (Glucocorticoid) - secreted by Adrenal Cortex
What endocrine gland controls diurnal / circadian rhythm? What sensory information does it use and what hormone does it produce?
Pineal gland; uses retina to indicate light/dark exposure; secretes melatonin hormone
When is melatonin serum concentration the highest?
Nighttime (during darkness)
When is melatonin serum concentration the lowest?
Daylight
What endocrine gland is only needed during childhood? What hormone does it produce?
Thymus gland; produces thymosin
What does thymosin do?
matures parts of the immune system (turns immature T-cells into mature T-cells)
What two location produce progesterone?
Placenta and Corpus luteum in ovary
Where are atrial natriuretic peptides produced?
Heart
Where is erythropoietin produced?
Kidneys
