Transcript The Endocrine System

The Endocrine System
Chapter 47
Endocrine System: The Body’s
Regulatory System
• The nervous system is involved with high speed
messages
• The endocrine system is slower and involves the
production, release, and movement of chemical
messages
– Endocrine glands – ductless glands that secrete
hormones into body fluids for distribution
– Exocrine glands – secrete chemicals (sweat, mucus,
digestive enzymes) into ducts which carry them to
appropriate locations
• The nervous and endocrine systems are
interrelated – some chemicals serve both as
hormones and neurotransmitters
Chemical signals
• Bind to specific receptors within target
cells or on their surface
• This triggers chemical events within
the target cell and results in a change
in its behavior
• Hormones coordinate metabolism,
growth, development, and
reproduction
Endocrine Glands and their
Hormones
• Hypothalamus
– In brain
– Receives information from body and
initiates endocrine responses
• Pituitary gland
– Below hypothalamus
– Two lobes – one releases hormones
directly into bloodstream, the other stores
and secretes hormones made in
hypothalamus
Hormones…
• Posterior pituitary hormones
– Oxytocin – involved in labor and nursing
– Antidiuretic hormone – makes the kidneys
increase water retention in response to
dehydration
• Anterior pituitary hormones
– Growth hormone - growth
– Prolactin – mammary gland development
– Follicle-stimulating hormone –
spermatogenesis and ovarian follicle growth
– Thyroid-stimulating hormone – stimulates the
thyroid to produce its hormones
Hormones…
• Pineal gland – also in brain
– Melatonin – modulates skin pigmentation and
controls biorhythms
• Thyroid – around trachea
– Thyroxine – controls metabolism
• Hyperthyroidism – high body temp, sweating, weight
loss, irritability, high blood pressure
• Hypothyroidism – weight gain, lethargy, coldintolerance
• Goiter (enlarged thyroid) – dietary iodine deficiency
Hormones…
• Pancreas – two antagonistic hormones
– Maintains blood glucose levels close to 90 mg/
100 mL
– Insulin – secreted when blood glucose levels
are high  stimulates cells to take up glucose
from the blood and convert to glycogen
– Glucagon – secreted when blood glucose levels
fall  stimulates the liver to convert glycogen to
glucose and release to bloodstream
– Type I diabetes – sudden on-set; insulindependent
– Type II diabetes – usually adults over 40; treated
with diet and exercise
Hormones…
• Adrenal glands – sit on top of kidneys
– Epinephrine and norepinephrine
• Released in response to stress (‘fight or
flight’)
• Glucose is released as well as fatty acids
• Rate and stroke volume of heart increases
• Blood is shunted away from skin, digestive
system, and kidneys, and sent to heart, brain,
and skeletal muscles
• Breathing rate increases and bronchioles in
lungs dilate
Hormones…
• Gonads (testes in males; ovaries in
females)
– Steroid hormones: androgens for males;
estrogens for females
– At puberty these stimulate the
development of the secondary sex
characteristics
– Primary androgen is testosterone
– Primary estrogen is estradiol