endocrine system Flashcards
how to the chemical messengers differ in nervous and endocrine systems?
nervous: neurotransmitters
endocrine: hormones
how do the receptors differ in nervous vs endocrine system
nervous: neuromuscular or neuroglandular junction
endocrine: variety of tissues, cells
how does the mode of transmission differ in nervous vs endocrine system?
nervous: neurons
endocrine: blood borne
how does response time differ in nervous vs endocrine system?
nervous: rapid - milliseconds to seconds
endocrine: slow reaction time - seconds to minutes to hours
how do target tissues differ in nervous vs endocrine systems?
nervous: other neurons, muscle cells, gland cells
endocrine: systemic broad - any cell in the body with a receptor for the hormone
the endocrine system is mostly regulated by _____ feedback loops
negative
what is a positive feedback loop in the body?
- child birth
- hormone (oxytocin) keeps increasing until baby is out
describe the feedback loop for glucose
- blood glucose drops after fasting
- pancreas releases glucagon (promote glycogen breakdown)
- blood glucose increases
- pancreas releases insulin (promotes glucose uptake)
what are the glands of the endocrine system
1) hypothalamus
2) pituitary gland
3) thyroid
4) adrenal glands
5) pancreatic islets
6) pineal gland
7) parathyroid
secondary functions:
8) heart
9) thymus
10) adipose tissue
11) digestive tract
12) kidneys
13) gonads (testes, ovaries)
the hypothalamus innervates which part of the pituitary?
posterior
the hypothalamus secretes hormones into which part of the pituitary?
anterior
the posterior pituitary is also known as the ____
neurohypophyses
the anterior pituitary is also known as the ______
adenohypophyses
how many hormones are secreted by the anterior pituitary? name them
1) TSH
2) ACTH
3) FSH
4) LH
5) PRL
6) GH
7) MSH (melanocyte stimulating hormone)
which hormones are released by the posterior pituitary?
-oxytocin and ADH
TSH
-targets the thyroid gland - stimulates production of T3 and T4
ACTH
-targets adrenal cortex - stimulates glucocorticoid secretion
FSH
- targets follicular cells in ovaries of females and nurse cells in testes of males
- stimulates follicle development and estrogen secretion in females and sperm maturation in males
LH
- targets follicular cells in ovaries of females and interstitial cells in testes
- stimulates ovulation, corpus luteum formation, and progesterone secretion
PRL
- prolactin
- targets female mammary glands and stimulates milk production
GH
- targets all cells in the body
- stimulates growth, protein synthesis, lipid mobilization, and catabolism
MSH
- melanocyte stimulating hormone
- targets melanocytes
- stimulates increased melanin production in epidermis
ADH
- antidiuretic hormone
- targets kidneys
- promotes reabsorption of water and elevation of both blood volume and blood pressure
oxytocin
- targets uterus and mammary glands
- causes labor contractions and milk ejection
- targets ductus deferent and prostate
- causes contraction of ductus deferent and prostate and ejection of secretions
describe the role of the hypothalamus in the anterior pituitary
- indirect control through release of regulatory hormones
- hormones released into hypophyseal portal system for delivery to anterior lobe of pituitary
describe the role of the hypothalamus in the posterior pituitary
- direct release of hormones
- sensory stimulation (innervation)
- osmoreceptor stimulation
pineal gland
- part of the epithalamus
- contains neurons, glial cells, pinealocytes (synthesize melatonin)
what is the role of melatonin
- slows maturation of sperm, oocytes, and reproductive organs
- production rate rises at night and declines during the day
what are the 3 layers of the adrenal cortex
1) zona glomerulosa
2) zona fasciculata
3) zona reticularis
what is the mnemonic used to remember what each layer of the adrenal cortex releases?
Salt (mineralocorticoids), sugar (glucocorticoids), sex (androgens)
hormones, targets, and effects of the zona glomerulosa
hormones: mineralcorticoids (primarily aldosterone)
targets: kidneys
effects: increase renal absorption of Na+ and water, accelerate urinary loss of K+ ion
hormones, targets, and effects of the zona fasciculata
hormones: glucocorticoids, cortisol, corticosterone
target: most cells
effects: release AAs from skeletal muscle, lipids from adipose tissue; promotes formation of liver glycogen and glucose; promotes peripheral utilization of lipids; anti-inflammatory effects
hormones, targets, and effects of the zona reticularis
hormones: androgens
targets: ?
effects: uncertain significance under normal conditions
which hormones are released from the adrenal medulla? what do they target? what are the effects?
hormone: E, NE
target: most cells
effects: increase cardiac activity, blood pressure, glycogen breakdown, blood glucose - release of lipids by adipose tissue
function of parathyroid hormone
raises the blood calcium level by breaking down the bone
role of calcitonin (released by thyroid)
- produced by C-cells of the thyroid
- decreases blood Ca++ levels
what are the functions of T3 and T4 released from T-cells of the thyroid?
- triiodothyronine (T3)
- thyroxine (T4)
- hormones regulate body temperature, metabolism, and heart rate.
what is the location of the thyroid?
anterior and inferior to the larynx
what is the location of the parathyroid glands?
posterior surface of thyroid
describe the homeostatic process of the thyroid hormones T3 and T4
- homeostasis disturbed by decreasing T3 and T4 in blood or low body temp
- stimulates receptor in hypothalamus which releases TRH
- anterior lobe of pituitary releases TSH
- thyroid follicles release T3 and T4
- T3 and T4 [ ] increases in blood and body temp rises
- homeostasis restored
what are the endocrine cells of the pancreatic islets?
1) alpha cells (glucagon)
2) beta cells (insulin)
3) f cells
4) delta cells (somatostatin; inhibited glucagon and insulin)
how does the heart act as an endocrine organ?
- maintains bp and blood volume
- affects water loss and Na+ ions
how do the kidneys act as an endocrine organ?
1) erythropoietin
- production of RBCs
2) renin
- release of hormones from adrenal cortex (aldosterone)
- regulate bp
how does the thymus act as an endocrine organ?
- several hormones released
- immune system response and lymphocytes
how are reproduction organs endocrine organs?
- estrogen, progesterone, testosterone
- eggs and sperm lymphocytes
