A&P2 Endocrine System

Endocrine System

A system of glands that produce and release hormones into the bloodstream. Hormones act as chemical messengers that regulate many body functions.

Responsibility of endocrine system

long-distance cellular communication, coordination, and control. This is essential for homeostasis.

Neural signaling

signals electrically, through action potentials and chemically, through neurotransmitters. Nervous system messaging is local, rapid and short lived.

Neural signaling: Receptors

Once a neurotransmitter is bound to a receptor, a response is elicited from the target cell. The response is quick and brief; e.g., movement, sensations and cognition.

Endocrine Signaling: Hormones

only uses chemicals called hormones to elicit a response. Hormones travel through the bloodstream to bind to receptors on target organs to elicit response.

Speed of endocrine signaling

signaling often takes longer and is longer-lasting compared to neural signaling, which is rapid and transient.

Glands

Major players in this system

Ductless and secrete hormones directly into the surrounding fluid.

Some have both endocrine and non-endocrine functions.

Some are secondary meaning they have a secondary endocrine function but they are not a primary endocrine organ.

Other Chemical signaling

Autocrine and Paracine

Autocrine signaling

Takes place in the same cell that secreted the chemical. EX:

Paracrine signaling

Targets neighboring cells but is restricted to those close by.

Receptor Specificity

Receptors are highly specific for the chemicals that they serve. Only cells with receptors specific to a given hormone will respond to that hormone.

Hormones function

Help regulate reproduction, growth and development, metabolism, fluid balance, sleep and many other body functions.

What kind of molecule is a receptor made of?

Protein

Where do the instructions for the protein come from?

The DNA

Amino acid based hormones

tend to be negatively charged (because of nitrogen) therefore they are polar. That means they like to be in water. They are water soluble (happy in water). they have to have a receptor.

Steroid based hormones