Chapter 17

Front 1

Autocrine Chemical Messengers

Back 1

Secreted by cells in a local area; influences the activity of the same cell from which it was secreted; e.g., prostaglandin

Front 2

Paracrine Chemical Messengers

Back 2

Produced by a wide variety of tissues and secreted into extracellular fluid; has a localized effect on other tissues; most common; e.g., somatostatin, histamine

Front 3

Neurotransmitter

Back 3

Produced by neurons; secreted into a synaptic cleft by presynaptic nerve terminals; travels short distances; influences postsynaptic cells; e.g., acetylcholine, epinephrine

Front 4

Endocrine Chemical Messengers

Back 4

Secreted into the bloo by specialized cells; travels some distance to target tissues; results in coordinated regulation of cell function; e.g., estrogen, growth hormone

Front 5

Characteristics of Endocrine System

Back 5

-Glands that secrete chemical messengers (hormones) into circulatory system
-Regulate activities of body structures
-Ligands: more general term for chemical signals

Front 6

Hormone Characteristics

Back 6

-Produced in small quantities
-Secreted into intercellular space
-Transported some distance in circulatory system
-Acts on target tissues elsewhere in body

Front 7

Similarity with Nervous System

Back 7

-Both systems associated with the brain
-May use same chemical messenger as neurotransmitter and hormone (epinephrine - flight or fight)
-Two systems are cooperative

Front 8

Differences with Nervous System

Back 8

-Mode of transport (nervous - axon; endocrine - blood)
-Speed of response (nervous - instant; endocrine - delayed)
-Duration of response (nervous - short; endocrine - long)

Front 9

Half Life

Back 9

The length of time it takes for half a dose of substance to be eliminated

Front 10

Long Half Life

Back 10

Regulate activities that remain at a constant rate through time. Usually lipid soluable and travel in plasma attached to proteins.

Front 11

Short Half Life

Back 11

Water-Soluable hormones as proteins, epinephrine, norepinephrine. Have a rapid onset and a short duration.

Front 12

Water Soluable Hormones

Back 12

Quick response so doesn't associate with protein; needs broken down faster; e.g., Proteins; Thyroid stimulating hormone, growth hormone

Front 13

Lipid Soluable Hormones

Back 13

-Steroids: Testosterone, Aldosterone
-Amino Acid Derivative: Thyroid Hormone
-Fatty Acid Derivative: Prostaglandins

Front 14

Chronic Hormone Regulation

Back 14

Relatively stable concentration of hormone is maintained in the circulation blood over a relatively long period. This pattern is exemplified by the thyroid hormones.

Front 15

Acute Hormone Secretion

Back 15

A hormone rapidly increases in the blood for a short time in response to a specific stimulus; e.g., epinephrine in response to stress.

Front 16

Episodic Hormone Secretion

Back 16

A hormone is stimulated so that it increases and decreases in the blood at a relatively consistent time and to roughly the same amount; e.g., reproductive hormones regulating menstruation.

Front 17

Control of Hormone Secretion

Back 17

1. The action of a substance other than a hormone on an endocrine gland
2. Neural control of endocrine gland
3. Control of secretory activity of one endocrine gland by hormone or neurohormone secreted by another endocrine gland

Front 18

Control by Neural Stimuli

Back 18

1. An action potential in a neuron innervating an endocrine cell stimulates secretion of a stimulatory neurotransmitter.
2. The endocrine cell secretes its hormone into the blood where it will travel to its target
3. An AP in the neuron stimulates secretion of an inhibitory neurotransmitter
4. the endocrine cell is inhibited and doesn't secret its hormone.

Front 19

Control by Hormonal Stimuli

Back 19

See slide show

Front 20

Negative Feedback

Back 20

1. Ant. Pituitary secretes tropic hormone, which travels in the blood to the target endocrine cell.
2. Hormone from the target endocrine cell travels to its target.
3. Hormone from target endocrine cell also has a negative feedback effect on the ant. pituitary and hypothalamus and decreases secretion of tropic hormone.

Front 21

Positive Feedback

Back 21

1. Ant. pituitary secretes a tropic hormone, which travels in the blood to the target endocrine cell
2. Hormone from target endocrine cell travels to target
3. Hormone from target endocrine cells also has a pos. feedback effect on ant. pituitary and increases secretion of tropic hormone

Front 22

Binding Site

Back 22

Portion of molecule where hormone binds

Front 23

Receptor site

Back 23

If the molecule is a receptor (like in a cell membrane) the binding site is called a receptor site

Front 24

Down Regulation

Back 24

-Rate at which receptors are synthesized decreases in some cells after the cells are exposed to a hormone
-Combination of hormones and receptors cna increase the rate at which receptor molecules are degraded

Front 25

Up-Regulation

Back 25

-Some stimulus causes increase in synthesis of receptors for a hormone, thus increases sensitivity to that hormone.
-Even if concentration of hormone doesn't change, sensitivity does

Front 26

Nuclear Receptors

Back 26

-Lipid-soluable hormones
-Pass through plasma membrane
-React either with enzymes in the cytoplasm or with DNA to cause transcription and translation

Front 27

Membrane Bound Receptors

Back 27

-Water-soluable hormones
-Interact with hormones that can't pass through the plasma membrane

Front 28

Intracellular Mediators

Back 28

Ions or molecules that enter cell or are produced in cell
-Can be produced because of G protein activation
-Regulate intracellular enzyme activities