Endocrine System

Crash Course Review of Endocrine System

• http://www.youtube.com/watch?v=WVrlHH14q3o

• This video clip will help you review some of the info that you just took notes on in your groups.

• Keep your notes out and add to them with any additional new information from the video.

Types of Signaling• Endocrine

– Hormones travel through the blood stream throughout the entire body– Act on a variety of tissues

• Paracrine– Target cells are near the secreting cells– Neurons, clotting factors

• Autocrine– Secreted molecules act on the secreting cell itself– T cell activation Immune response

• Pheromones– Molecules are secreted into the external environment– Marking territory, attracting mates, etc.

Hormone Responses• Hormones can cause different responses on

different tissues– determined by types of receptors on target tissue

and signal transduction pathways– Ex. Epinephrine• Different responses in different target tissues

Types of Hormones• Peptide (Water Soluble)

– Can’t cross membrane– Released by exocytosis– Bind to cell-surface signal receptors– Can cause a cytoplasmic response and alter gene transcription

inside cell– http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=s

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• Steroid Hormones (lipid soluble)– water insoluble– Travel in blood via transport proteins– Can easily diffuse across cell membranes– Bind to intracellular signal receptors and cause changes in gene

transcription– http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=s

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Steroid or Peptide Hormone?

Steroid or Peptide

Hormone?

Negative Feedback

• Maintains homeostasis• Feedback loop initiated by a stimulus• Response reduces the initial stimulus

Negative Feedback in Menstrual Cycle

Menstrual and Ovarian Cycles

• Feedback between Glands• Low estrogen and

progesterone cause the hypothalamus to increase GnRH

• High GnRH causes the pituitary to release FSH and LH

• FSH causes follicle to develop in ovary

• FSH and LH cause follicle to release estrogen

Continued…•Estrogen increases the thickness of uterine lining

•Major increase in LH causes ovulation•Ruptured follicle (corpus luteum) releases estrogen and progesterone

•Progesterone thickens and maintains uterine lining•Increase of estrogen and progesterone slow release of GnRH ( decrease FSH and LH)

Continued…

•No Fertilization: •Fertilization:

•Corpus luteum disappears and progesterone and estrogen decrease.

•Uterine lining sheds

•Embryo implants in uterus and forms a placenta.•Placenta releases HCG which causes corpus luteum to continue to release progesterone and estrogen (which will maintain the uterine lining) until the placenta begins to make it’s own estrogen and progesterone.

Male Hormones•GnRH from the hypothalamus stimulates the pituitary to release FSH and LH.

•Testosterone causes testes to produce sperm

•FSH stimulates cells in the testes to nourish sperm

•LH stimulates the testes to release testosterone.