5.5: pineal gland

**pineal gland:

-part of epithalamus

-produces ___, circadian effector hormone

-melatonin transmits time of day/ year from brain to body

melatonin

melatonin

-produced via photoneuroendocrine pathway

-intrinsically ___ retinal ganglion cells: ip RGC

-light response neurons

→suprachiasmatic nuclus (SCN): __ in hypothalamus

→superior cervical ganglion (SCG): superior-most ganglion in ___ __

→pineal gland

photosensitive, circadian master clock, sympathetic trunk

inhibition of melatonin

-___ recognize presence of light

-inhibitory signal sent to ___ via retinohypothalamic tract

-melatonin production inhibited

ip RGCs, SCN

production of melatonin

-___ recognizes absence of light

-___ signal sent to SCN

-SCN activates sympathetic nervous system

-sympathetic preganglionic fibers travel to SCG

-postganglionic fibers release ___ in pineal gland (allows for formation of melatonin)

ip RGCs, stimulatory, norepinephrine

hypothalamus regulates activity of reticular formation

daytime: reticular formation ___ → wakefulness

nighttime: reticular formation __ → sleepiness

stimulated, suppressed

SCN sets circadian patterns

-melatonin inhibits SCN communication with ____ → allows for onset of sleep

-melatonin induces sleep-promoting changes in physiology (like reduced body temp & blood pressure)

-low during day, high at night, allows body to detect ___

-___ ___ prevent melatonin production during day (even if it’s dark)

hypothalamic sleep center, day vs night, circadian genetics

seasonal melatonin release

summer: short nights = ___

winter: long nights = ___

less melatonin, more melatonin

effects of light on melatonin

-blue light has greatest power to: ___

turn off melatonin production

thyroid gland

-mainly composed of ___

→follicular cells secrete __ hormone

→colloid: thyroid hormone precursor aka iodine

-parafollicular cells: secrete ___

colloid-filled follicles, thyroid, calcitonin

thyroid hormone

-__ hormones that behaves like ___ hormone

-increases metabolic rate

-regulates tissue growth & development

→ specially important for skeletal & nervous system growth

-___ effect on gonadal hormones

-thyroid stimulating hormone (TSH) stimulates __ response

amine, steroid, permissive, TH

*hyposecretion of thyroid gland:

-caused by ___ deficiency: thyroid unable to produce TH

iodine

*hypersecretion of thyroid gland: 

-abnormal antibodies mimic ___, causing abnormal TH release

-elevated metabolic rate, sweating, irregular heartbeat

TSH

calcitonin: when there’s (high/ low?) calcium in blood

-secreted in response to ___

-inhibits __ activity

-promotes ___

high, hypercalcemia, osteoclast, osteoblast

parathyroid glands

-embedded in ___ ___

-produce ____ hormone

posterior thyroid, parathyroid

parathyroid hormones: when there’s (high/ low?) calcium in blood

-released in response to ___

-inhibits ___ activity

-promotes ___ activity

-decreases urinary excretion of calcium

-promotes calcitriol (active form of vitamin d) synthesis

low, hypocalcemia, osteoblast, osteoclast