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Now we are at the endocrine system. The endocrine system is a control system, it helps regulate homeostasis. It is involved in stress response, and plays a big role in growth and development.

It is composed of ductless glands and hormones which are released into extracellular space. When a hormone is release it triggers specific target cells.


Endocrine, hormone,

The target cells have receptors – 3 kinds specifically.

1- Distant targets (travel through the bloodstream)
2- Local targets (travels through extra cellular fluid to neighbor cells)
3- Self targets (acts on releasing cell)

Types of hormones-

Lipid soluble (steroids)
Biogenic amites (thyroxine)
Proteins and peptides (insulin, oxytocin, growth hormone)
Eicosanoids (prostaglandins, leukoyrienes, thromboxenes)

Some reactions from hormones-
Aldosterone- Elevated Na + K
Cortisol- Turns down immune system (helps blood glucose)

The purpose of a hormone is to change the activity of a target cell or organ.

Fixed membrane receptor: Activates second messenger inside cell, changes activity of enzyme inside the cell.
Mobile receptor- Hormone+cytoplasmic receptor enters nucleus and binds to DNA, which alters transcription.

Endocrine second messenger system hormone

Second messenger system

Phosphorylates to change shape, essentially turning on or off. (Kinase- hear that and you know somethings being phosphorylated.)

Tips on memorizing hormones-
If it has A or Stimulatory the hormone is coming from anterior pituitary
If it has R or I it is coming from hypothalamus

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