Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
28 Cards in this Set
- Front
- Back
|
Autocrine chemical messengers |
Released by cells and have a local effect on same cell type from which chemical signals released |
|
|
Parocrine chemical messengers |
Released by cells and affect other cell types locally without being transported in blood |
|
|
Neurotransmitter |
Produced by neurons and secreted into extracellular spaces by presynaptic nerve terminals; travels short distances; influences postsynaptic cells |
|
|
Endocrine chemical messengers |
Type of intercellular signal. Produced by cells of endocrine glands, enter circulatory system, and affect distant cells |
|
|
Characteristics of the endocrine system |
Hormones: - Produced by small quantities - Secreted into intercellular space - Transported some distance in circulatory system - Acts on target tissues elsewhere in body The glands secrete chem messengers into circulatory system Regulate activities of body structures |
|
|
Compare nervous and endo system |
- Both associated with brain - may use the same chem messenger as neurotransmitter and hormone. Epinephrine/norepinephrine - both cooperative |
|
|
Differences of nervous and endo system |
- mode of transport Axon (n) Blood (e) - speed of response Milliseconds (n) Seconds (e) - duration of response Milliseconds/seconds (n) Minutes/days (e) Amplitude modulated (n) Frequency modulated (e) |
|
|
Gen characteristics of hormones |
- communication with target cells - distribution Dissolve in blood plasma ans are transported unbound or are reversibly bound to plasma proteins; chaperones Distributed quickly because they circulate in the blood |
|
|
Half life of hormones |
Lenght of time it takes for half a dose of substance to be eliminated from circulatory system |
|
|
Long half life of hormones |
- Regulate activities that remain at a constant rate through time - usually lipid soluble and travel in plasma attached proteins |
|
|
Short half life of hormones |
- water soluble hormones as proteins, epinephrine, norepinephrine - have a rapid onset and short duration |
|
|
Lipid soluble hormone transport |
- travel in the bloodstream bound to binding proteins "chaperones" - without binding proteins, lipid soluble hormones would quickly diffuse in capillaries and be degraded by enzymes - if blood levels begin to decline, some of the bound hormone is released by the binding proteins - circulating concentration of free hormones that use binding proteins remains more stable than that of hormones that do not us binding proteins |
|
|
Water soluble hormone transport |
Water soluble are large so they do not readily diffuse through the walls of the capillaries; therefore they tend to diffuse from the blood into tissue space more slowly |
|
|
Chronic hormone secretion |
A relatively stable concentration of hormone is maintained in the circulating blood over a relatively long period. This pattern is exemplified by the thyroid hormones |
|
|
Acute hormone secretion |
A hormone rapidly increases in the blood for a short time in response to a specific stimulus |
|
|
Episodic hormone secretion |
A hormone is stimulated so that it increases and decreases in the blood at a relatively consistent rime and to roughly the same amount |
|
|
Humoral secretion of hormone |
The action of a substance other than a hormone on an endocrine gland |
|
|
Neural secretion of hormone |
Control of endocrine gland via synaptic communication |
|
|
Hormonal secretion of hormone |
Control of secretory activity of one endocrine gland by hormone or neuro hormone secreted by another endocrine gland |
|
|
Regulation by humoral stimuli |
- bloodborne molecules can directly stimulate the release of some hormones - when blood level of the particular molecule changes, the hormone is released in response to the molecules concentration |
|
|
Regulation by neural stimuli |
1. Action potential in a neuron innervating an endocrine cell stimulates secretion of a stimulator neurotransmitter 2. Endocrine cell secretes its hormone into the blood where it will travel to its target 3. Action potential in the neuron stimulates secretion of an inhibitory neurotransmitter 4. Endocrine cell is inhibited and does not secrete it's hormone |
|
|
Regulation by hormonal stimuli |
1. Neurons in hypothalamus release stimulatory hormones, called releasing hormones 2. These hormones stimulate the relate of tropic hormones from the anterior pituitary 3. Hormone from the target endocrine cell also inhibit the hypothalamus and anterior pituitary from secreting the releasing hormone and the tropic hormone 4. Hypothalamus can also secrete inhibiting hormones |
|
|
Target tissue specificity and response |
- hormones exert their actions by binding to proteins called receptors - portion of the molecule where hormone binds is called binding site - if the molecule is a receptor like in a cell membrane, the binding site is called a receptor site - hormone/receptor site is specific - purpose of binding to target tissue Is to elicit a response by the target cell |
|
|
Decrease in receptor number |
- normally degraded and replaced on a normal regular basis Down regulation - rate at which receptors are synthesized decreases in some cells after the cells are exposed to a hormone - combination of hormones and receptors can increase the rate at which receptor molecules are degraded. This combined form is taken into the cell by phagocytosis and then broken down |
|
|
Increase in receptor number |
Up regulation - some stimulus causes increase in synthesis of receptors for a hormone, thus increases sensitivity to that hormone |
|
|
Membrane bound receptor |
- water soluble hormones bund to membrane bound receptors. Intergral proteins with receptor site at extracellular surface - interact with hormones that cannot pass through the plasma membrane Hormones Water soluble or large molecular weight hormones Attachment of hormone causes intracellular reaction Hormones thar bind to membrane bound receptors include proteins, peptides, and some amino acid deravatives, such as epinephrine and norepinephrine |
|
|
Lipid soluble hormones and nuclear receptors |
- latent period of several hours because time is required to produce MRNA and protein - hormone - receptor complexes are eventually degraded within the cell, limiting lenght of time hormones influence the cells activities - steroid hormone aldosterone affects it's target cells in the kidneys by stimulating the synthesis of proteins that increase the rate of Na+ and K+ transport. The result is a reduction in the amount of Na+ and an increase in the amount of K+ lost in the urine |
|
|
Membrane bound receptors and sink amplification |
- membrane bound receptors activate responses in two ways: 1. Receptors alter the activity of g proteins at the inner surface of the plasma membrane 2. Other receptors directly alter the activity of intracellular enzymes - these intracellular pathways elicit specific reposses in cells including the production of intracellular mediators - some intracellular mediators are called second messengers Is a chemical produced inside a cell once a hormone or another chemical messenger binds to certain membrane bound receptors In some cases, this coordinate set of events is referred to as a second messenger system |
