Endocrine Lecture Flashcards
Define hormone and endocrine system.
Hormone: chemical messengers that travel through the bloodstream to other tissues/organs
Endocrine System: an internal communication system that reacts over time, the respone persists, and many organs are effected
What are several organs of the endocrine system?
-Hypothalamus
-Pineal Gland
-Pituitary Gland
-Adrenal Gland
-Thyroid Gland
-Parathyroid Gland
-Thymus
-Pancreas
Contrast endocrine with exocrine glands
Endocrine: secrete products directly into bloodstream
Exocrine: secrete substances into a duct on an epithelial surface
Describe the anatomical relationship between the hypothalamus and the pituitary gland.
-Overall, the hypothalamus monitors the bloodstream to coordinate hormonal activity
-The hypothalamus releases hormones that regulate when the anterior pituitary cells produce hormones
-The hypothalamus releases nerve signals which stimulates the posterior pituitary to release stored hormones (ADH and oxytocin)
Distinguish between the anterior and posterior lobes of the pituitary gland.
-Anterior Pituitary: largest portion of the pituitary and is linked to the hypothalamus through capillaries. Hypothalamic hormones regulate the anterior pituitary cells.
-Posterior Pituitary: composed of nervous tissues and not a true gland. It is linked to the hypothalamus through nerve cells
Describe the pineal gland location and structure.
List hormones produced, how their secreted, and function
Location: Beneath posterior end of the corpus callosum
Hormone: melatonin to help sleep
Function: Regulates circadian rhythm. It influences the timing of puberty
Describe the thymus location and structure.
List hormones produced, how their secreted, and function
Location: bilobed gland superior to the heart
Function: important for immune system
Describe the thyroid gland location and structure.
List hormones produced, how their secreted, and function
Location: the largest, purely endocrine gland. It looks like a butterfly with 2 lobes and an isthmus
Hormone: Thyroid hormone is secreted in response to TSH. Parafollicular cells secrete calcitonin to keep calcium levels low
Function: increase metabolic rate, oxygen consumption, heat production, and low calcium levels
Describe the parathyroid gland location and structure.
List hormones produced, how their secreted, and function
Location: four glands that are partially embedded in the posterior surface of the thyroid gland
Hormone: parathyroid hormone (PTH) that increases blood calcium levels
Function: increasing calcium levels increases the absorption of calcium, decreases urinary excretion, and increases bone resorption
Describe the adrenal medulla location and structure.
List hormones produced, how their secreted, and function
Location: the inner core, 10-20% gland
Hormone: releases epinephrine, noepinephrine, some dopamine. This causes fight/flight mode which increases blood flow, heart rate, and decreases digestion/urine
Function: Acts as endocrine gland and a ganglion of the sympathetic nervous system
Describe the adrenal cortex location and structure.
List hormones produced, how their secreted, and function
Location: surrounds the adrenal medulla and has three layers of glandular tissues
Hormone:
-aldosterone: Sodium retention, Potassium excretion ( electrolyte balance)
-androgens: libido and male development
-estradiol: small amount, helps with menopause
-also secretes cortisol and corticosterone
Function: secretes important hormones to live
Describe the pancreatic islets location and structure.
List hormones produced, how their secreted, and function
Location: groups of cells within the pancreas
Hormone:
-Alpha cells secrete glucagon between meals when glucose is low
-Beta cells secrete insulin during and after meals when glucose and amino acid levels are rising
Function: control blood glucose levels
Describe the gonads location and structure.
List hormones produced, how their secreted, and function
Location: ovaries and testes
Hormones:
-ovarian hormones: estradiol, progesterone, and inhibin
-testicular hormones: testosterone, androgens, and inhibin
Function: produce sex cells and steroid hormones
How is hormone release stimulated? (Three ways)
- Neural stimuli: nerve fibers supply some endocrine glands and cause hormones to be released
ex: childbirth stimulates stretch receptors which causes the hypothalamus to release oxytocin - Hormonal stimuli: pituitary hormones stimulate other endocrine glands to release TH, sex hormones and cortisol.
- Humoral stimuli: blood borne stimuli
ex: rising blood glucose concentrations causes insulin to be released
What happens when two hormones stimulate the same target cells? (3 effects)
- Synergistic: multiple hormones act together for greater effect. Ex: FSH and teststerone work together for sperm production
- Permissive: one hormone enhances the target organ’s response to second hormone. Ex: estrogen prepares uterus for action of progesterone
- Antagonistic: one hormone opposes the action of another hormone. Ex: insulin lowers blood glucose, glucagon raises blood glucose.
