The endocrine system regulates long term processes such as what?
Growth
Development
Reproduction
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?
Direct communication
This uses chemical signals to transfer information from cell to cell within a single tissue and is the most common form of intracellular communication.
Paracrine Coimmunication
This is when endocrine cells release hormones into the bloodstream and alters metabolic activities of many tissues and organs simultaneously.
Endocrine Communication
These are specific cells that possess receptors needed to bind and read hormonal signals.
Target cells
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".
Hormones
This is ideal for crisis management, occurs across synaptic clefts, chemical message is "neurotransmitter" and is limited to a very specific area.
Synaptic communication
What are the three classes of hormones?
Amino acid derivatives
Peptide hormones
Lipid 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.
Epinephrine
Norepinephrine
Dopamine
Serotonin
Melatonin
These are a chains of amino acids and most are synthesized as prohormones.
Peptide Hormones
These proteins are more than 200 amino acids long and have carbohydrates side chains.
Glycoproteins
Give an example of short chain polypeptides.
ADH (antidiuretic hormone)
OXT (oxytocin)
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?
Hypothalamus
thymus
heart
GI tract
others
These are steroid hormones derived from cholesterol.
Lipid derivatives
Lipid derivatives are released by what?
reproductive organs
cortex of adrenal glands
kidneys
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
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?
Transport Protiens
The blood stream contains substantial reserves of bound what?
Hormones
This is a protein molecule to which a particular molecule binds strongly and responds to several different hormones.
Hormone Receptors
In regards to hormone receptors, different tissues have different combinations of what?
Receptors
In regards to hormone receptors, presence or absence of specific receptor determines what?
Hormonal sensitivity
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.
Eicosanoids
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?
Activator
inhibitor
cofactor
The first messenger results in change in rates of what?
metabolic reactions
Give three examples of important Second Messengers.
Cyclic - AMP (cAMP)
Cyclic - GMP (cGMP)
Calcium ions
Cyclic - AMP (cAMP) is a derivite of what?
ATP
Cyclic - GMP (cGMP) is a derivative of what?
GTP
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?
Target Cell
The presence of a hormone triggers a decrease in the number of hormone receptors.
Down-regulation
In down-regulation, when levels of particular hormones are high, cells become more or less sensitive to it?
Less
The absence of a hormone trigger increases in number of hormone receptors. This is known as?
Up- regulation
In up-regulation, when levels of particular hormones are low, cells become more or less sensitive to it?
More
This enzyme complex couples to a membrane receptor and is involved in the ling between the firs messenger and second messenger.
G Protien
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?
Amino acids
Hormones and intracellular receptors alter the rate of DNA what in the nucleus?
Transcription
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
Endocrine Reflexes can be triggered in what three ways?
Humoral stimuli
Hormonal stimuli
Neural stimuli
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.
They hypothalamus
Reflexes that have pathways that include both neural and endocrine components are known as what?
Neuroendocrine Reflexes
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