The endocrine system regulates long term processes such as what?
What does the endocrine system use to relay information between cells?
Chemical messengers called hormones
The exchange of ions and molecules between adjacent cells across gap junctions that occurs between two cells of the same type is known as what?
This uses chemical signals to transfer information from cell to cell within a single tissue and is the most common form of intracellular communication.
This is when endocrine cells release hormones into the bloodstream and alters metabolic activities of many tissues and organs simultaneously.
These are specific cells that possess receptors needed to bind and read hormonal signals.
These stimulates synthesis of enzymes or structural proteins, can increase or decrease rate of synthesis, or turn existing enzyme or membrane channel "on" or "off".
This is ideal for crisis management, occurs across synaptic clefts, chemical message is "neurotransmitter" and is limited to a very specific area.
What are the three classes of hormones?
Amino acid derivatives
What are the two ways that hormones travel in the body?
they can circulate freely or travel bound to special carrier proteins
These are small molecules structurally related to amino acids and are derivatives of tyrosine.
Amino Acid Derivatives
Give examples of amino acid derivatives.
These are a chains of amino acids and most are synthesized as prohormones.
These proteins are more than 200 amino acids long and have carbohydrates side chains.
Give an example of short chain polypeptides.
ADH (antidiuretic hormone)
each 9 amino acids long
Give an example of peptide hormones with small proteins.
GH (growth hormone) - 191 amino acids
PRL (prolactin) - 196 amino acids
What glands secret short chain polypeptides and small proteins?
These are steroid hormones derived from cholesterol.
Lipid derivatives are released by what?
cortex of adrenal glands
Why do circulating steroid hormones remain in circulation longer than secreted peptide hormones?
they are bound to specific transport proteins in the plasma
What kind of hormones remain functional for less than 1 hr?
Free hormones are broken down and absorbed by cells of the what?
Liver or Kidneys
Enzymes in plasma or interstitial fluids
Why do thyroid and steroid hormones remain in circulation for so long?
Because they are bound`
The thyroid and steroid hormones, upon entering the bloodstream, become attached to what?
The blood stream contains substantial reserves of bound what?
This is a protein molecule to which a particular molecule binds strongly and responds to several different hormones.
In regards to hormone receptors, different tissues have different combinations of what?
In regards to hormone receptors, presence or absence of specific receptor determines what?
These kinds of hormone are NOT lipid soluble and unable to penetrate plasma membranes. Rather, they bind to receptor proteins at outer surface of plasma membrane.
Catecholamines and Peptide Hormones
These hormones ARE lipid soluble and diffuse across the plasma membrane to reach receptor proteins.
What are the rules with first and second messengers?
bind to receptors in plasma membrane
cannot have direct effect on activities inside target cell
use intracellular intermediary to exert effects.
The first messenger leads to the second messenger. The first messenger may act as an enzyme what?
The first messenger results in change in rates of what?
Give three examples of important Second Messengers.
Cyclic - AMP (cAMP)
Cyclic - GMP (cGMP)
Cyclic - AMP (cAMP) is a derivite of what?
Cyclic - GMP (cGMP) is a derivative of what?
This is the binding of a small number of hormone molecules to membrane receptors and leads to thousands of second messenger cells.
The process of Amplification
The process of amplification magnifies effects of hormone on what?
The presence of a hormone triggers a decrease in the number of hormone receptors.
In down-regulation, when levels of particular hormones are high, cells become more or less sensitive to it?
The absence of a hormone trigger increases in number of hormone receptors. This is known as?
In up-regulation, when levels of particular hormones are low, cells become more or less sensitive to it?
This enzyme complex couples to a membrane receptor and is involved in the ling between the firs messenger and second messenger.
Adenylate cyclase is activated when hormones bind to receptor at membrane surfaces and what else happens?
Changes concentration of second messenger cyclic - AMP within the cell
Opening of calcium ion channels in the membrane, release of calcium ions from intracellular stores are triggered by what?
Activated G proteins
The building bricks of a peptide bond are what?
Hormones and intracellular receptors alter the rate of DNA what in the nucleus?
How is it possible for the hormones and intracellular receptors to change the rate of DNA transcription in the nucleus?
Changes the patterns of proteins synthesis
Hormones directly affect what part of the target cell?
Metabolic activity and structure
These are a functional counterpart of neural reflexes, and in most cases controlled by negative feedback.
Endocrine Reflexes can be triggered in what three ways?
What is humoral stimuli?
Changes in composition of extracellular fluid.
What is a hormonal stimuli?
Arrival or removal of specific hormone
What is neural stimuili?
arrival of neurotransmitters at neuroglandular junctions
This kind of endocrine reflex involves only one hormone and controls hormone secretion by the heart, pancreas, parathyroid gland, and digestive tract.
Simple Endocrine Reflex
This kind of endocrine reflex involves one or more intermediary steps and has two or more hormones.
Complex Endocrine Reflex
This gland provides the highest level of endocrine control.
Reflexes that have pathways that include both neural and endocrine components are known as what?
Complex commands are issued by changing what two things?q
The amount of hormones secreted and the pattern of hormones release
What two hormones tend to be released in sudden bursts?
Hypothalamic and pituitary hormones