Like this study set? Create a free account to save it.

Sign up for an account

Already have a Quizlet account? .

Create an account

Endocrine System

consists of glands that secrete chemical messengers, hormones, into the circulatory system


produced in small quantities secreted into intercellular space, transported in the blood, act on target tissues, regulate activities of body


site of nervous and endocrine interaction

Similarities of Endocrine and Nervous

both associated with brain, same chemical messenger, work cooperatively

Differences of Endocrine and Nervous

mode of transport, speed of response, duration of response, modulation

Amplitude Modulation

used by endocrine system, concentration of hormone determines the strength of the signal and the magnitude of the response

Frequency Modulation

used by nervous system, strength of the signal depends n the frequency of action potentials

Hormone Characteristics

stability, communication, distribution

Lipid Soluble Hormones

stability characteristic, exert prolonged effect, regulate activities that remain at a constant rate through time, usually travel in plasma attached to proteins, diffuse into cell

Water Soluble Hormones

stability characteristic,regulate activities that have a rapid onset and short duration, include proteins epinephrine and norepinephrine, do not bind to plasma proteins or readily diffuse out of the blood quickly broken down by enzymes or are taken up by tissues within seconds


hormones dissolve in blood plasma and are transported unbound or reversibly bound to plasma proteins, distributed quickly in blood

Chronic Regulation

relatively stable concentration of a hormone is maintained in the circulating blood for a long period of time, thyroid hormone

Acute Regulation

hormone rapidly increases in concentration in the blood for a short time in response to a stimulus, epinephrine in response to stress

Episodic Regulation

hormone is stimulated cyclically so it increases and decrease in the blood at a relatively constant time, female reproductive hormones

Negative Feed Back

maintain homeostasis, control the secretion of most hormones, 3 ways 1. concentration of no-hormone substance (humoral) 2. neural stimuli 3. hormonal stimuli

Humoral Stimuli

changes in the extracellular concentration of a non-hormone substance, ex. blood glucose levels increase insulin release

Neural Stimuli

stimulation by the nervous system, can stimulate hormone release or inhibit it

Hormonal Stimuli

stimulation by a hormone from another endocrine tissue

Binding Site

portion of molecule where hormone binds, receptor molecules specific to hormone, purpose is to elicit response by target cell

Membrane bound receptors

span plasma membrane, for water soluble hormones or large molecular weight hormones, attachment causes intracellular reaction

Intracellular Receptors

located in cytoplasm or nucleus, bind to lid soluble hormones or small molecules, react with enzymes or DNA, mRNA produced

G proteins

activated by membrane bound receptors, three sub units, alpha beta and gamma

Inactive State

GDP bound to alpha subunit of G protein

Active State

GTP bound to alpha subunit of G protein

G Protein and Ion Channels

G protein binds to Ca channels opening them to let in Ca, produces response to hormone


membrane receptors alter activity of enzymes, activate guanylate cyclase to make GTP into ___, intracellular mediator, alters intracellular enzymes, producing response to hormone

Phosphorylate Proteins

membrane bound receptor with part inside cell acting as enzyme to phosphorylate proteins, ex. insulin receptors

Intracellular Receptor Mechanisms

slow acting because time is required to produce mRNA and proteins

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

Voice Recording