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28 terms

Functional Organization of the Endocrine System Ch 17

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Endocrine System
consists of glands that secrete chemical messengers, hormones, into the circulatory system
Hormones
produced in small quantities secreted into intercellular space, transported in the blood, act on target tissues, regulate activities of body
Hypothalamus
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
Distribution
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
cGMP
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