Big Picture
What is the overall goal of the endocrine system?
-Maintain homeostasis via chemical signaling
-Affect growth, metabolism, mood, etc. via hormones
Name the 3 types of stimuli for hormone secretion and define them.
Hormonal: one hormone tells a cell to release or inhibit another hormone (tropic)
Humoral: based on the levels of a non-hormone in the blood, a hormone is released to "level" it out
Neural: neurons use a neurotransmitter to tell a cell to release/inhibit a hormone
How does the anterior pituitary differ in tissue from the hypothalamus & posterior pituitary? What connects the hypothalamus & pituitary gland?
A.P.: made of epithelial tissue
Hypothalamus & P.P.: made of nervous tissue
The infundibulum connects the two, and within that is the hypothalamic-hypophyseal tract.
What hormones are released by the thyroid gland? What hormone is released by the parathyroid gland? What helps release these?
Thyroid:
- Thyroid hormones (T3 & T4): follicle cells & thyroid follicles
- Calcitonin: parafollicular cells
Parathyroid:
- Parathyroid hormone (PTH): chief cells
Explain the differences between the adrenal cortex and the adrenal medulla.
Adrenal Cortex: epithelial, endocrine organ releasing endocrine hormones. Steroid derived & hydrophobic.
Adrenal Medulla: nervous, neuroendocrine organ releasing neuroendocrine hormones. A.A. derived & hydrophilic.
What are the 3 types of chemical signals and what differentiates them?
Bonus points if you can give examples!
Endocrine: produced by endocrine cell and travels by blood to distant cell
Paracrine: produced near target cell and travels by extracellular fluid to nearby cell
Autocrine: produced by self and travels via extracellular fluid to self
Summarize the negative feedback loop and give an example of a hormone that uses a negative feedback loop.
Bonus points if you can also name a positive feedback loop and differentiate it from a n.f.l.!
Stimulus -> Receptor -> Control Center -> Effector/Response -> Back to Appropriate Level
Any hormone other than oxytocin is n.f.l.
Name the 2 hormones created by the hypothalamus & P.P. and briefly state their purpose.
Antidiuretic Hormone (ADH): decreases urine production by increasing osmolarity in the body.
Oxytocin: focuses on reproductive actions such as uterine contractions & feeding babies via mammary glands through a p.f.l.
List the primary effects of thyroid hormones.
1. Regulation of metabolic rate (gluconeogenesis & protein catabolism)
2. Thermoregulation (due to metabolism)
3. Promotion of growth & development
4. Synergism with the sympathetic nervous system
5. Erythropoiesis (RBC formation)
Name the three cells and hormones released by said cells in the pancreas.
Alpha Cells - Glucagon
Beta Cells - Insulin
Delta Cells - Somatostatin
BAD
P IGS
Name the 3 classifications of hormones.
Type of tissue that makes them:
- Endocrine vs nervous
Chemical composition:
- amino acid derived vs steroid
Solubility in water:
- hydrophobic vs hydrophilic
(Bonus points if you can detect which one uses intracellular receptors)
What are the two possible ways of hormone signaling and where does second messenger signaling fall under?
Membrane bound receptors (all hydrophilic hormones and some hydrophobic hormones use this)
- Second messenger signaling falls under this category
Intracellular receptors (only some hydrophobic hormones use this)
How do the hypothalamus & the A.P. communicate?
Due to different tissues, they use tropic hormones to communicate via the capillary beds in the hypothalamic-hypophyseal portal system
What's the relationship between calcitonin and parathyroid hormone (PTH)?
Calcitonin is released by the thyroid gland (parafollicular cells) and PTH is released by the parathyroid gland (chief cells). Both are used to regulate the calcium levels in the blood, thus are stimulated via humoral stimuli. Calcitonin is released when hypercalcemia endures by inhibiting osteoclasts. PTH is released when hypocalcemia endures by stimulating osteoclasts.
What nervous system stimulates glucagon production & inhibits insulin production?
The sympathetic nervous system.
Name 3 organs part of the endocrine system and give an example of a hormone associated with it.
Hypothalamus/Anterior Pituitary: TSH, ACTH, PRL, FSH, LH, GH, somatostatin
Thyroid: thyroid hormone (T3 & T4) & calcitonin
Parathyroid: parathyroid hormone
Adrenal Glands: aldosterone, cortisol, androgens
Pancreas: glucagon, insulin, somatostatin
Pineal Gland: melatonin
Thymus: thymosin & thymopoietin
Gonads: testosterone, estrogen, progesterone
Other organs that could be mentioned but don't count since we didn't cover them: adipose tissue, heart, kidneys
How does intracellular receptor signaling work?
1) Hydrophobic hormone diffuses into the target cell
2) Hormone binds to an intracellular receptor & enters the nucleus of the cell
3) Hormone-receptor complex interacts with the DNA to initiate a cellular change (protein synthesis is affected)
Name some short-term and some long-term effects of growth hormone.
Short-term:
-inhibits glucose uptake in skeletal muscle
-stimulates gluconeogenesis in liver
-increased blood glucose concentration
-stimulates lipolysis in fat
-increased blood fatty acid concentration
Long-term:
-insulin-like growth factor (IGF) is released by liver, muscle, bone & other tissues
-stimulates glucose uptake by cells
-decreased blood glucose concentration
-stimulates cell division
-increased growth of bone & other tissues
-stimulates protein synthesis
-increased mass of muscle & other tissues
What disorders could hyperthyroidism and hypothyroidism cause? Do these have any physical appearance of sort?
Bonus points if you can expand on why these physical appearances occur!
Hyperthyroidism:
Grave's Disease - goiter in neck
Hypothyroidism:
Iodine Deficiency - goiter in neck
Hashimoto's Disease - goiter in neck
What are the primary effects of cortisol?
1. Gluconeogenesis
2. Release of fatty acids
3. Release of amino acids
4. Anti-inflammatory
5. Down-regulates immune system
6. Stress response
Compare & contrast the endocrine system from the nervous system.
Both: use chemical signaling
Nervous: uses synapses, effects are quick & short-lived, paracrine system
Endocrine: moves through blood, slower & long-lasting, goes anywhere blood can reach
(Answer can vary)
What are the steps of second messenger signaling?
Like a relay!
1) Hormone A (the first messenger) binds to its receptor in the plasma membrane
2) Receptor activates a peripheral protein (protein inside membrane)
3) Peripheral protein activates an enzyme
4) Enzyme catalyzes the formation of a second messenger
5) Second messenger initiates a series of events in the cell that leads to changes in its activity (signal amplification)
Explain the growth hormone regulation.
Answer will be drawn out.
If viewing this online, refer to the fourth video under the "hypothalamus & pituitary gland" video folder located on canvas in the endocrine system resources page. This question is answered starting at about the 10 minute timestamp.
Explain the process of thyroid hormone production.
1) Iodide is consumed & absorbed in blood.
2) It's transported through the follicle into the colloid.
3) Iodide ions are converted to iodine atoms that attach to thyroglobulin
4) When iodinated thyroglobulin enters back into the follicle by endocytosis, it's chopped up by lysosome enzymes into T3 & T4
5) T3 & T4 are released into the blood.
- T3 is more potent but is only 10% of this release
- T4 is less potent and is 90% of this release, so T4 could be converted into T3
Name the 4 hormones involved with gluconeogenesis.
Bonus points if you can name the 2 hormones involved with fluid balance!
Glucagon, growth hormone, cortisol, thyroid hormone.
Bonus: ADH & aldosterone.