Chapter 19: Endocrine System Flashcards
What are the general characteristics of the endocrine system? (3)
1.) Chronic regulation of homeostasis
-slow & prolonged responses
-acute = nervous system
2.) Interrelated with nervous system
(hypothalamus & posterior pituitary)
3.) Ductless system
-hormones produced by specialized cells
carried in blood stream
What are hormones?
-Substance synthesized by a specific organ or tissue & secreted
-Act on target cells
(have specific receptors for specific hormones)
if a hormone is secreted into extracellular spaces this called what signaling?
paracrine signaling
if the blood carries the hormone to other sites this is known as what?
endocrine signaling
for the chemistry of hormones, what are the four different categories? briefly describe each category
- ) Steroids
- made from cholesterol, non-polar - ) Peptides
- polar - ) Amines
- derived from amino acids
- polar & non-polar - ) Eicosanoids
- most are non-polar
- paracrine signals (prostaglandins)
describe steroid hormones and give examples
Lipid soluble therefore can cross cell membrane
transduction –> regulation of DNA transcription
Examples: estrogens like estradiol androgens like testosterone aldosterone cortisol
describe amine hormones
what are the most important ones made by?
Derived from either tyrosine or tryptophan Some are membrane soluble (thyroxine) Some are not (epinephrine) Most important ones are made by: -thyroid -adrenal medulla
describe peptide hormones
short chains of amino acids
cannot cross cell membrane
all pituitary hormones
describe Eicosanoid hormones
derived from fatty acids
most cross cell membranes
coordinate functions in extracellular fluid
e.g. prostaglandins
describe negative feedback (4)
- gland is sensitive to concentration of substance
- concentration exceeds limits –> prevents gland from secreting hormone
- concentration decreases –> secretion increases
- results in relatively stable concentration of both substance & hormone
the hypothalamus sends signals to the…..
pituitary gland
true or false: the pituitary is the MOST important endocrine gland for regulation.
true
describe the two lobes of the pituitary gland
Posterior Lobe:
- does not make any hormones
- mostly hypothalamic axons
Anterior Lobe:
-5 types of endocrine cells
-controlled by hypothalamic regulatory hormones
(releasing hormones/inhibiting hormones)
what are two posterior pituitary hormones?
oxytocin and antidiuretic hormone (ADH)
who three things does oxytocin cause and what is it significant in?
-causes contraction of muscles in uterine walls
-causes muscles associated with milk ejection to contract
-cause contraction of prostate gland
-Significant in emotional bonding
Familial
Romantic
what does ADH do?
causes kidney to decrease water excretion
increases blood volume –> rise in BP
what are the 7 anterior pituitary hormones?
- ) Melanocyte stimulating hormone (MSH)
- ) Follicle stimulating hormone (FSH)
- ) Luteinizing hormone (LH)
- ) Growth Hormone (GH)
- ) Thyroid stimulating hormone (TSH)
- ) Prolactin (PRL)
- ) Adrenocorticotropic hormone (ACTH)
the thyroid gland consists of what 2 things and lies inferior to what?
2 lobes + isthmus
inferior to larynx
the thyroid gland has two types of cells. What are they and describe them
Follicular cells
- line follicle cavities
- filled with thyroglogulin colloid
- remove Iodine from blood
- secrete T3 and T4
Parafollicular cells
-produce calcitonin
Follicular cells secrete 2 hormones. What are they? describe them
-Thyroxine (T4) ↑ glycogenolysis ↑ protein synthesis ↑ growth -Triiodothyronine (T3) same as T4 but 5x’s more potent
Parafollicular cells secrete 1 hormone. What is it? describe it
Calcitonin
↓ blood Ca+2 & PO4
↑ renal excretion
↑ osteoblast activity
describe the parathyroid glands
Posterior surface of thyroid
many tightly packed secretory cells
oxyphil & transitional cells = immature
chief cells = produce parathyroid hormone
what does the parathyroid hormone do?
↑ blood Ca+2
↓ renal Ca+2 & PO4 excretion
↑ osteoclast activity
↑ calcitriol = intestinal Ca+2 absorption
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fun stuff
Where is the thymus located?
Thoracic cavity, posterior to sternum
What does the Thymus produce? describe it
produces thymosin
- enhances lymphocyte production & competence
- most active in infancy & childhood
what two parts are associated with the adrenal glands?
adrenal cortex and adrenal medulla
what are the three zones in the adrenal cortex? what do they produce?
1.) Glomerulosa aldosterone --> Na+ retention Fasciculata cortisol --> glycogen formation 3.) Reticularis androgens --> secondary sexual characters
what is located in the adrenal medulla? what are they and what do they produce?
- chromaffin cells which are modified postganglionic cells of the SNS
- epinephrine & norepinephrine
what are the three hormones in the kidneys? describe them
Renin -start cascade to increase blood pressure Erythropoietin (EPO) -erythrocyte production Calcitriol -increases absorption of digested Ca+2
What is the hormone in the heart? describe it
Atrial natriuretic peptide (ANP)
- suppresses aldosterone & ADH
- decrease blood volume & blood pressure
where is the pancreas located?
posterior to stomach and attached to the duodenum of stomach
the group of pancreatic cells that secrete hormones (have the endocrine function in the pancreas) are called what?
Islets of Langerhans
What are the three different Islets of Langerhan cells? what hormone does each produce?
- ) Alpha cells
- glucagon- increases blood sugar - ) Beta cells
- insulin- decreases blood sugar - ) Delta cells
- somatostatin- inhibits glucagon and insulin secretion
- antagonizes GH
the male gonads are made up of what two cells?
interstitial cells and Nurse (sertoli) cells
what do interstitial cells secrete?
-androgens
-testosterone
Stimulate nurse cells
secondary sex characteristics
what do nurse cells secrete?
secrete inhibin
- ↓ FSH from anterior pituitary
- Stimulate spermatogenesis
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weird wording with stuff just look at it
in the pineal gland there are _______ in _________ that produce _________ which is responsible for what?
pineacytes; epithalamus;
Melatonin
-circadian rhythms
-puberty (?)
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