Endocrine System & Hormones Flashcards
Define homeostasis
the condition of equilibrium (balance) in the body’s internal environment
What are 2 examples of positive feedback loops?
Blood clotting
Contractions
Explain.
What are 2 examples of negative feedback loops?
high body temperature
low body temp
Explain.
What is a hormone?
mediator molecules (chemical signals) that are released by an endocrine gland, too regulate activities in cells in other parts of the body
What are 3 types of endocrine glands?
Pituitary, thyroid, parathyroid
What are 3 types of endocrine tissues/organs?
hypothalamus, thymus, kidneys
What is considered the “master gland”?
hypothalamus
What are 3 functions of hormones?
Helps regulate composition and volume of interstitial fluid
Control growth and development
Helps regulate metabolism and energy balance
What will hormones bind to?
Specific receptors on specific target cells/tissues
What are the two types of hormones (in terms of travel)?
Circulating and local
How do lipid soluable hormones illicit a response?
Diffuse directly into cell and bind to receptors on the nucleus
(need protein through blood stream)
How do water soluable hormones illicit a response?
Cannot diffuse directly into a cell, signal 2nd messenger response
(independent through blood stream)
Responsiveness of target cell depends on what 3 things?
- Concentration of hormone in the blood (increased = increased response of target cell)
- Abundance of receptors on a cell (increased = increased response of target cell)
- Influence of other hormones
What is synergism?
the combined effect of 2 hormones is greater than each on its own
What are the two pituitary glands?
Anterior and posterior
Which pituitary gland releases hormones that regulate body function?
Anterior pituitary gland
What are the two thyroid hormones?
T3 and T4
What is the role of thyroid hormones?
- Sets basal metabolic rate (oxygen consumption, energy expedition at resting state)
- Metabolism (synthesis of carbs, proteins, fats)
- Heat production (increased metabolic activity, leads to increased heat)
- Regulates tissue growth and development (CNS)
- Cardiovascular system (effects on heart rate and blood pressure)
What is hyperthyroidism? What is the opposite?
overactivity of thyroid gland causing increased thyroid hormone secretion
Hypothyroidism - underactivity of thyroid gland causing decreased thyroid hormone secretion
Explain the negative feedback control of thyroid hormone release
Low blood levels of T3/T4 or metabolic rate occur in blood and are detected
Hypothalamus releases TRH (Thyrotropin-releasing hormone)
TRH travels from hypothalamus down hypophyseal portal veins to anterior pituitary glands
Anterior pituitary glands are stimulated to release TSH (thyroid-stimulating hormone)
TSH enters blood stream and travels to thyroid gland to stimulate thyroid follicles
Follicles are stimulated and release T3 and T4 into blood stream
T3 inhibits TSH and TRH, therefore stops stimulus from producing thyroid hormone
