Endocrine System II Flashcards
simple endocrine pathway
- stimulus received by endocrine cells
- stimulates endocrine cells -> secretes hormone
- hormone travels via bloodstream -> interacts with target cells -> physiological response
simple neuroendocrine pathway
- stimulus received by sensory neuron
- stimulates neurosecretory cell -> secretes neurohormones
- hormone travels via bloodstream -> interacts with target cell -> physiological response
- ex: milk release during nursing
hypothalamus
- regulates MANY hormones
- neuroendocrine gland
- links NS and endocrine systems
- connected to pituitary gland by portal vessels
Releasing Hormones (RH)
trigger Anterior Pituitary (AP) to secrete certain hormone
Inhibiting Hormones (IH)
inhibit AP from secreting hormones
hormone cascade pathway
- RHs trigger AP to secrete Stimulating Hormones (SH)
- SHs trigger gland to secrete specific hormones
- Negative feedback: higher hormone levels -> less RH and SH. lower hormone levels -> more RH and SH
tropic hormone
stimulate production of other endocrine hormones
nontropic hormone
stimulate target cells directly
antidiuretic horomone (ADH) and oxytocin
- peptide neurohormones
- produced by neurons in hypothalamus
- sent to Posterior Pituitary (PP)
- stored in vesicles in PP until needed
what are the two lobes of pituitary glands in humans?
Posterior Pituitary and Anterior Pituitary
Posterior Pituitary (PP)
-neuroendocrine gland
-stores and secretes:
[ADH - water retentio in kidneys]
[oxytocin - milk, contrations, care, bonding]
Anterior Pituitary
Endocrine gland - hormones released into blood
- produces and secretes both tropic and nontropic hormones
- every AP hormone controlled by at least 1 RH (some also by an IH)
thyroid hormones
endocrine gland - hormones stimulate cellular metabolism in virtually all cells
- maintain normal BP, reproductive functions
- regulate digestive, reproductive function
SEQ Thyroid Hormone Regulation
hypothalamus ->Thyrotropin Releasing Hormone (TRH) -> AP -> Thyroid Stimulating Hormone (TSH) -> Thyroid Gland -> Thyroid Hormones: T3 (3 Iodine) and T4 (4 Iodine) -> all cells -> response
hyperthyroidism
- too much thyroid hormone
- high body temp, profuse sweating, weight loss, irritability, high BP
- ex: Grave’s Disease (antibodies bind to TSH receptors, trigger T3 and T4 production)
hypothyrodism
- too little thyroid hormone
- weight gain and lethargy, slower metabolism, intolerance to cold, goiter
- ex: Hashimoto’s Thyroiditis (immune destruction of thyroid cells, inability to produce T3 and T4)
molting (ecdysis)
- larva grows in discrete stages
- molts in between
- endocrine pathway between begins in larval brain
Juvenile Hormone (JH)
- produced in brain
- “remain a larva”
Prothoracicotropic Hormone (PTTH)
- produced in brain
- “make ecdysteroids”
ecdysteroids
- produced in prothoracic gland
- “molt”
pathway of invertebrate endocrine control
- after hatching, larva has high levels of JH, no PTTH and no Ecdysteroids
- larva eats -> grows -> internal body presses organs and exoskeleton
- pressure against exoskeleton = stimulus for PTTH production
what happens when JH levels are high?
grow and molt into larva
what happens when JH levels are low?
molt into pupa -> metamorphosis into adult
what are some applications of hormones?
can be used as insecticides
- synthetic ecdysteroids: premature molting -> death
- synthetic JH: larva would never become adults
parathyroid
4 glands in connective tissue surrounding thyroid
parathyroid hormone (PTH)
- regulates blood Ca2+ levels
- secreted by parathryoid
what two hormones does blood calcium regulation involve? what is special about these two?
- parathyroid: secretes PTH to increase Ca2+
- thyroid: secretes calcitonin to decrease Ca2+
the two hormones are anatagonistic
SEQ low blood Ca2+ regulation
stimulus: low blood Ca2+ -> parathyroid -> PTH -> Multiple effects -> response (increase in blood Ca2+)
Multiple effects:
- bone releases Ca2+
- kidneys reabsorb Ca2+
- liver produces Vitamin D -> increase Ca2+ from intestines
is blood calcium regulation an example of positive or negative feedback?
negative
SEQ high blood Ca2+ regulation
stimulus: high blood Ca2+ -> thyroid -> calcitonin -> multiple effects -> response (decrease in blood Ca2+)
multiple effects:
- bone retains Ca2+
- kidneys excrete Ca2+
adrenal glands
- small glands on top of each kidney
- 2 parts:
(1) central - adrenal medulla
(2) outer - adrenal cortex - function as distinct glands but both regulate metabolism, response to stress
adrenal medulla
- neuroendocrine gland
- short-term stress response (fight or flight)
- secretes epinephrine and norepinephrine (water soluble hormones)
- activated by nerve impulses
what is the benefit of the nervous system involvement and release of water-soluble hormones
it’s fast
during stress, what happens with the adrenal medulla?
- hypothalamus activates adrenal medulla via nerve impulse
- adrenal medulla releases epinephrine, norepinephrine
(1) more blood to brain, muscles, heart
(2) glycogen breakdown to glucose
(3) increase metabolic rate (up to 100%)
(4) increase O2 delivery - higher HR, stroke volume, breathing rate - short-term response
adrenal cortex
- endocrine gland
- responds to chronic stress
- secretes corticosteroids (lipid-soluble)
- activated by endocrine signal
- long-term response
SEQ stress in adrenal cortex
stress -> hypothalamus -> CRF -> AP -> ACTH -> Adrenal Cortex -> response (corticosteriods)
response:
- glucose synthesis from non-carb sources
- muscles broken down -> increase blood glucose
- immune suppression
