Endocrine System (2) Flashcards
Exam 2
What is the endocrine system made up of?
glands
tissues
cells
What do glands/tissues/cells do?
secrete hormones
communication and coordination is critical for ___
homeostasis
What are the 5 things the endocrine system regulates?
- growth and development
- metabolism
- water balance
- reproduction
- stress responses
Endocrine glands are traditional sources of ____
hormones
What are hormones?
- chemical messengers
- secreted into blood
- target cells (specific receptors)
- distant organs or cells
What is endocrinology?
study of endocrine system
What are exocrine glands?
- ducts
- epithelial surface or mucosa
- extracellular effects (food digestion)
What are endocrine glands?
- ductless, release into blood
- intracellular effects (cell metabolism)
What are characteristics of the nervous system?
- chemical and electrical signals
- neurotransmitters at synapse
- starts and stops quickly
- targets specific organ
- usually local, specific effects
Characteristics of endocrine system?
- chemical signals only
- hormones into the blood
- slower to start and stop
- hormones go everywhere
- typically general, widespread effects
What are neuroendocrine cells?
don’t exclusively categorize as neurons or gland cells
-like neurons but release secretions into bloodstream (hormones secreted by specialized neurons such as oxytocin)
What regulates each other and coordinates activities?
- neurons influence hormone secretion
- hormones stimulate/inhibit neurons
What do the hypothalamus and pituitary gland do?
- regulates more functions than any other gland
- function of other endocrine glands dependent on signals from hypothalamus/pituitary
- important link in neural and hormonal regulation
What “fundamental functions” does the hypothalamus regulate?
- water balance
- libido and childbirth
- hunger
- circadian rhythm
The hypothalamus functions through the ____ ____
pituitary gland
What is the infundibulum?
suspends pituitary from hypothalamus
What are the two structures of the pituitary?
- Anterior Pituitary (anterior lobe)
2. Posterior Pituitary (posterior lobe)
Two facts about the anterior pituitary?
- 3/4s of pituitary
- origin: pouch in roof of embryonic pharynx (throat)
Two facts about the posterior pituitary?
- down-growth from brain (hypothalamus)
- retains connection to brain
What connects the hypothalamus to the anterior pituitary?
a network fo small blood vessels
What is the hypophyseal portal system?
Blood flows from one capillary bed to another (rare)
- hypothalamus sends chemical signals (hormones) into primary capillaries
- travel a short distance (portal venules) to anterior pituitary
- leave bloodstream through secondary capillary network (stimulate or inhibit anterior pituitary
Hypothalamic hormones regulate anterior pituitary cells by….
hypothalamic- resealing and -inhibiting hormones
What happens between the hypothalamus and posterior pituitary?
- controlled by hypothalamic nuclei
- neurosomas produce hormones
- nerve cell axons to infundibulum to posterior lobe
True or False
nerve tissues is a true gland
False
nerve tissue is not a true gland
How many hormones are produced by the hypothalamus?
Eight
How many hormones regulate the anterior pituitary?
six
What do releasing hormones do?
-stimulate anterior pituitary to secrete hormones
What do inhibiting hormones do?
-suppress pituitary output
What two hormones are stored in the posterior pituitary?
- oxytocin
- antidiuretic hormone
What are the six hormones synthesized by the anterior pituitary?
- Follicle-stimulating hormone (FSH)
- Lutenizing Hormone (LH)
- Thyroid Stimulating Hormone (TSH)
- Adrenocorticotropic Hormone (ACTH)
- Prolactin (PRL)
- Growth Hormone (GH)
What does FSH do?
- stimulates maturation of follicles containing eggs
- stimulates production of sperm
What does LH do?
- stimulates ovulation
- testes to secrete testosterone
What does TSH do?
-stimulates the thyroid gland to secrete the thyroid hormone
What does ACTH do?
-stimulates adrenal cortex
What does PRL do?
-stimulates mammary glands to synthesize milk (after birth)
What does GH do?
- promotes tissue growth
- -mobilizes energy from fat
- -raises levels of electrolytes
- -stimulates protein synthesis, mitosis, and cellular differentiation
Corticotropin-releasing hormone (CRH) stimulates the secretion of ___
ACTH
Thyrotropin-releasing hormone (TRH) stimulates the secretion of ___
TSH (and PRL)
Growth Hormone- releasing hormone (GHRH) stimulates the secretion of ___
GH
Somatostatin (SST) inhibits the secretion of ___
GH (and TSH)
Gonadotropin-releasing hormone (GnRH) stimulates the secretion of ___
LH and FSH
Dopamine (DA)/ prolactin-inhibiting hormone (PIH) inhibits the secretion of ___
PRL
Negative Feedback Inhibition Example
Chain of signals in TH release:
- hypothalamus secretes TRH to stimulate pituitary
- pituitary secretes TSH to stimulate thyroid
- thyroid responds by secreting TH
- TH
- feedback to both hypothalamus and pituitary
- reduce TRH and TSH
- keeps thyroid hormone in check
What two hormones are released when hypothalamic neurons are stimulated?
Oxytocin (OT) Antidiuretic Hormone (ADH)
(both are stored and released by the posterior pituitary)
Yes or No
Does the posterior pituitary synthesize OT and ADH?
No
What does Oxytocin (OT) do?
-stimulates uterine smooth muscle contractions
contractions during labor and within mammary glands
What does the antidiuretic hormone (ADH) do?
regulates fluid balance
-stimulates kidneys to retina water/reduce urine output
What do neuroendocrine reflexes do?
release of hormones in response to nerve signals
True and False
oxytocin is a positive feedback control
True
