Hormone Type of Released Stimulus Mechanism of Functions Too
hormone from action (targets) much/too
1. Melatonin Amine Pineal gland Darkness; Circadian
- trp secreted rhythm, immune
derivative at night function, anti-
2. Parathyroid Parathyroid Low In bones, PTH Increases No
hormone glands (chief plasma increases plasma Ca2+ parathyroid
(PTH) cells) Ca2+ expression of concentration. glands: die
RANKL on Increases from
osteoblasts by phosphate hypocalcemia.
increasing cAMP release from
and decreases OPG bone and
expression so that decreases
more osteoclasts phosphate
are formed leading reabsorption in
to reabsorption kidney.
from bones. Targets bone
In kidney, PTH and kidney.
ions going into
blood and prevents
loss of urinary
calcium and thus,
PTH also acts on kidney to
calcitriol (Vit D3)
3. Calcitriol Steroids Skin Low Calcitriol binds to Increases
plasma Vit D receptor and expression of
Ca2+ recruits ca2+ channels/
PTH is crucial for transporters in
forming active Vit kidney and
D3. intestine and
also RANKL and
effect is to
4. Calcitonin Peptide C cells High Protects the
(parafollicular plasma skeleton from
cells) of the [Ca2+] Ca2+ loss during
thyroid gland pregnancy and
5. Vasopressin Peptide Synthesized Low blood Vasopressin binds Increase water
in pressure to P.M. receptors o reabsorption.
hypothalamus, and high cells and triggers Targets distal
released plasma increase in AC and convolutic
from PPT. osmolarity cAMP, which tubule/collecting
activates PKA. This duct cell
causes aquaporin-2 membrane.
water pores to
exocytose on the apical membrane of
the collecting duct
Water moves into
cell and blood.
6. Steroid Synthesized ACTH, Increase Na+
Aldosterone in the adrenal High and K+
cortex. plasma reabsorption.
[K+], Targets the
angiotensi distal tubule and
n II. collecting duct.
Inhibited Targets kidney
7. Atrial Heart Increased Decrease Na+
natriuretic blood and H2O
peptide volume reabsorption,