Central Endocrine Glands Flashcards
What are the central endocrine glands? Where are they located?
secrete hormones that target peripheral endocrine glands in addition to non-endocrine tissue
-pituitary gland (anterior and posterior)
-hypothalamus and pineal gland
Which of the central endocrine glands have solely endocrine functions and which have mixed functions?
-pituitary gland (solely endocrine function)
- hypothalamus and pineal gland (mixed functions)
What are tropic hormones?
hormones with the primary function of regulation secretion of another hormone
- also maintain the structure of target peripheral gland or cause it to grow (trophic action)
What is the anatomical difference between the anterior and posterior pituitary gland?
anterior (separate endocrine gland, containing endocrine cells, controlled by hormones secreted from hypothalamus)
posterior (anatomical extension of hypothalamus, neurosecretory cells directly reach down to it)
What brain area projects to the posterior pituitary? Does this same area also project to
the anterior pituitary?
hypothalamus connects directly only to the posterior pituitary gland
What are the two hormones released from the posterior pituitary gland, and what do
they do?
vasopressin: released in order to conserve H2O, increases reabsorption of H2O in the kidney, minor role in regulation bp cia arteriolar smooth muscle contraction.
oxytocin: stimulates uterine contractions during childbirth, stimulates ejection of milk from mammary glands during breastfeeding, cognitive effects (bonding btwn mother and infant, possibly btwn couples)
What are hypophysiotropic hormones? Where are they released from?
hormones that inhibit or promote the release of anterior pituitary hormones, released from the hypothalamus (some control the release of multiple)
what do somatotropes secrete?
growth hormone
what do thyrotropes secrete?
thyroid stimulating hormone (TSH)
what do corticotropes secrete?
adrenocorticotropic hormone (ACTH)
what do gonadotropes secrete?
follicle-stimulating hormone (FSH) and luteinizing hormone (LH)—called gonadotropins
what do lactotropes secrete?
prolactin (PRL)
What is the hypothalamic-hypophyseal portal system? How is it different than regular
capillary beds?
: hypothalamic capillary bed that recombines into portal vessels to anterior pituitary, where re-branches out into secondary capillary bed
What is a 3-hormone chain of command? Where are each of the three hormones
secreted?
three hormones are secreted to bring about wanted change.
1.) corticotropin-releasing hormone
2.) adrenocorticotropic hormone
3.) cortisol
How does the negative feedback loop of the 3-hormone chain of command work?
the last hormone released keeps all hormones at their set point
What are the four things that allow normal growth to occur?
1.) genetics
2.) adequate diet
3.) freedom from chronic disease and stress
4.) normal level of growth influencing hormones
How many growth spurts occur during childhood? What are they?
two
1.) between 0-2, GH
2.) adolescence (puberty), estrogen and testosterone
What particular hormones increase during growth spurts?
growth hormone, sex hormones
Is growth hormone secreted in adults? What are its metabolic effects?
yes
1.) enhances breakdown of triglycerides in adipose tissue (increases fatty acid blood levels)
2.) increases glucose output by liver (increases glucose blood levels, decreases glucose muscle reuptake)
3.) stimulates amino acid uptake and protein synthesis, especially in muscle
What causes secretion of IGF-1? What does IGF-1 do?
:insulin-like growth factor 1
- promotes growth of soft tissue by hypertrophy(size) and hyperplasia(#) of cells
Growth obviously includes lengthening bones. During growth, do bones also widen? Do
soft tissues grow, or just bones?
bones and soft tissue grow in length and width
What does hypertrophy mean? How about hyperplasia?
hypertrophy: increasing size of cells
hyperplasia: increasing number of cells
What are osteocytes, osteoblasts, and chondrocytes?
osteocytes: mature bone cells
osteoblasts: immature bone cells
chondrocytes: makes up cartilage, secrete extracellular matrix, division controlled by GH (via IGF-1 release)
What is an epiphyseal plate?
the growth plate, made of cartilage and converted to bone following puberty
How does bone lengthening occur? Why does it stop at the end of puberty?
by laying layers of cartilage on top of epiphyseal plate, while transforming the bottom of the plate into bone
-stops when estrogen causes ossification of epiphyseal plate
What changes in growth hormone levels would cause dwarfism?
disruption in secretions or responsiveness to GH
What changes in growth hormone levels would cause gigantism?
overproduction of GH during childhood
What changes in growth hormone levels would cause acromegaly?
onset of GH overproduction during adulthood
- continued growth in bone width (not length), skin and connective tissues
What does the suprachiasmatic nucleus (SCN) do? What does the pineal gland do in
relation to it?
: area of hypothalamus that serves as master biological clock over body’s daily rhythm
- SCN entrained to circadian rhythms via melatonin secreted from pineal gland in the brain (Pineal gland increases melatonin secretion in the dark)
What hormone does the pineal gland secrete?
melatonin
what hypophysiotropic hormone promote the release of GH? Which inhibits the release of GH?
promotes: growth hormone-releasing hormone
inhibits: somatostatin
