Endocrine System Chemical Control Endocrine System A system glands - - PowerPoint PPT Presentation

Endocrine System

Chemical Control

Endocrine System

• A system glands that release chemical

messengers (hormones) to coordinate body functions

• 10 major endocrine glands
• Hormones are necessary for cell communication

and coordination of cell processes

Chemical Messengers

Function of the Endocrine System

• Regulates the growth, metabolism,

development and overall function of the human body

• Works closely with the nervous system to

maintain homeostasis through feedback mechanisms

Nervous Versus Endocrine

Use the diagram on p. 648 to compare and contrast the nervous and endocrine systems

Hormones

• Chemical messengers that are transported in

the circulatory system

• Produced and secreted by endocrine glands
• Target a variety of cells to have multiple

effects (target cells)

• Long distance signaling

Hormones

Hormone Classification

• Classified based on their solubility and chemical

structure Hormones

Proteins and Peptides

Lipid Soluble

Water Soluble

Steroids Amines

Peptides Proteins Amines Steroids

Chemical Type Structure Example Peptides/Proteins Chains of amino acids Insulin, Glucagon, Growth Hormone, ADH Amino Acid Derivatives (Amines) One or two amino acids Epinephrine, Norepinephrine, Melatonin Steroids Synthesized from cholesterol Testosterone, Estrogen, Cortisol (Glucocorticoid)

Hormone Classification

Water Soluble (Peptides, Proteins, Amines)

• Target a protein receptor on the cell surface
• Initiate signal transduction pathway that may

involve a second messenger (cAMP)

• Cellular response
• Faster response than lipid soluble hormones

Lipid Soluble (Steroids)

• Diffuse through plasma membrane
• Binds to a receptor in cytoplasm or nucleus
• Complex acts as a transcription factor that

regulates gene expression

• Slower response because of the regulation of

gene activity

Significant Endocrine Glands

Significant Endocrine Glands

• 1. Hypothalamus: Connects nervous system to

endocrine system, receives information and sends out nervous or endocrine signals, controls the pituitary gland

• 2. Pituitary Gland: Composed of nervous and

endocrine tissue, “master gland”, releases 9 different hormones

Hypothalamus

Pituitary Gland

Feedback Mechanisms

Feedback Mechanism

• Self-regulating mechanism that increases or

decreases the level of a particular substance

• 1. Positive Feedback: Enhances an already

existing response

• 2. Negative Feedback: Maintains homeostasis,

common in the endocrine system

Positive Feedback Example

Negative Feedback Examples

• Blood glucose levels – insulin and glucagon
• Blood volume (water) – anti-diuretic hormone

(ADH)

Blood Glucose Levels: Controlled by the action of insulin and glucagon

Kidney Structure

Melatonin

• Controls rhythmic activities, such as

sleep/wake cycles

Growth Hormone

• Controls growth and
• ther metabolic

functions by stimulating protein synthesis

Epinephrine (Adrenaline)

• Responding to stress or emergencies

Crash Course: Endocrine System Hormonal Communication

Watch the following two videos on the endocrine system and hormone communication