Chapter 17: The Endocrine System

Introduction

The endocrine system:

  • creates hormones to send to the bloodstream

  • is studied through the practice of endocrinology

Glands

Types of glands:

  • Exocrine glands: Have ducts to carry secretions outside the glands

  • Endocrine glands: Has no ducts and instead has secretions directly carried to the blood

Nerves and the endocrine system:

  • Both serve the purposes of internal regulation

  • The nervous system is faster in enacting change in minutes, while the endocrine system is slower through enacting change in hours or days

The Hypothalamus and Pituitary Gland

The hypothalamus:

  • is attached to the pituitary gland which hangs below the hypothalamus

  • produces various hormones, such as oxytocin (for contractions in mothers) and anti-diuretic hormone (for urinary regulation)

Pituitary Hormones

Anterior pituitary hormones:

  • Follicle-stimulating hormone: Stimulates secretion within the ovaries

  • Luteinizing hormone: Stimulates ovulation (the release of eggs from the ovaries)

  • Thyroid-stimulating hormone: Stimulates the thyroid to secrete hormones

    • Thyroid: Gland that regulates metabolism, aids hormonal action, and helps to regulate hormones

  • Adrenocorticotropic hormone: Enables the flight or flight response with adrenaline

  • Prolactin: Aids in the synthesis of milk

  • Growth hormone: Stimulates mitosis and differentiation of cells as well as protein synthesis, lipid metabolism, and carbohydrate metabolism

The Pineal Gland

  • Attached to the roof of the posterior corpus callosum

  • Shrinks at age 7

  • During puberty, it synthesizes melatonin at night

The Thymus

  • is part of the endocrine and immune system

  • produces T-cells

  • shrinks with age

The Thyroid

  • aids in metabolism, oxygen circulation, body heat, appetite, growth hormone regulation, and calcium control

  • Parathyroid: A helper on the back of the thyroid to regulate calcium

The Adrenal Glands

  • synthesize adrenaline, a stimulant

The Pancreas

  • creates glucagon, which is released to increase blood-glucose levels

  • also creates insulin to absorb glucose in the blood stream

    • malfunction can result in different types of diabetes mellitus

Gonads

  • includes the ovaries and testes

    • the ovaries produce estrogen and progesterone

    • the testes produce testosterone