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Endocrine System
Chapter 8
Overview of Hormones
The endocrine and nervous systems often work together to bring about homeostasis.
The blood stream transports hormones throughout the body.
Overview of Hormones
Each hormone acts on a certain type of tissue called its target tissue.
Organs, tissues, or cells lacking the specific receptor do not respond to its stimulating effects.
Negative Feedback Loop
A decrease in function in response to a stimulus
The system controls how much product it makes by shutting down manufacturing when levels of output or the amount of accumulated product gets too high Example # 1: the regulation of the blood glucose
level in the body Example # 2: regulation of body temperature
Negative Feedback Loop
Positive Feedback Loop
An increase in function in response to a stimulus
“A” produces more of “B” which in turn produces more of “A”
Only a few positive feedback loops occur in the human endocrine system. Example: the process of birthing a child
Positive Feedback Loop
Glands
Glands
Exocrine glands – secretions released into ducts opening onto an epithelial surface
Endocrine glands – ductless organs that secrete their molecules directly into the bloodstream
Glands
Endocrine glands are activated by other hormones
Hypothalamus
Controls the pituitary gland Receives information from the nervous
system
Pituitary
Location: Inferior to the hypothalamus Known as the master gland
I. Anterior Pituitary
1. Growth hormone (GH) General metabolic hormone Major effects are directed to growth of skeletal muscles and
long bones
I. Anterior Pituitary
2. Prolactin (PRL) Stimulates and maintains milk production following
childbirth Function in males is unknown
I. Anterior Pituitary
3. Adrenocorticotropic hormone (ACTH) Regulates endocrine activity of the adrenal cortex
which makes a hormone called cortisol (helps the body manage stress)
I. Anterior Pituitary
4. Thyroid-stimulating hormone (TSH) Produces the hormone thyroxine
Regulates the rate of metabolism
I. Anterior Pituitary
Gonadotropic hormones – Regulate hormonal activity of the gonads 5. Follicle-stimulating hormone (FSH)
Stimulates follicle development in ovaries Stimulates sperm development in testes
I. Anterior Pituitary
Gonadotropic hormones – Regulate hormonal activity of the gonads 6. Luteinizing hormone (LH)
Triggers ovulation Prepares uterus for fertilized egg Stimulates testosterone production in males
II. Posterior Pituitary
1. Oxytocin Stimulates contractions of the uterus during labor Causes milk ejection
II. Posterior Pituitary
2. Antidiuretic hormone (ADH) Can inhibit urine production In large amounts, causes vasoconstriction leading to
increased blood pressure
Posterior Pituitary Anterior Pituitary
Mnemonic Device for anterior and posterior pituitary gland Anterior pituitary
FLAT PIG FSH LH ACTH TSH
Prolactin (Ignore) Growth Hormone
Posterior pituitary Audio Osmosis = AO = ADH and Oxytocin
Mnemonic Device
Hormone Targeted Area Produces
F FSH Ovaries and Testes
Sperm and egg
L LH Ovaries and Testes
Ovulation and testosterone
A ATCH Adrenal Gland CortisolT TSH Thyroid ThryoxineP Prolactin Breast MilkI Ignore - -G GH Muscles and
bonesGrowth of muscles and bones
Anterior Pituitary Gland Chart
Mnemonic Device
Hormone Targeted Area Produces
A ADH Kidneys Inhibit urine production
O Oxytocin Uterus and breast Uterine contraction and milk letdown
Posterior Pituitary Gland Chart