Ch. 5 Properties Of Receptors

Front 1

specificity

Back 1

Receptors show _________ for the messenger

They generally bind only one messenger or a class of messengers.

Front 2

messenger

Back 2

A single _________ cell can often bind to more than one type of receptor, and these receptors may have different affinities for the messenger.

Front 3

target

Back 3

A single ______ cell may have receptors for more than one type of messenger.

Front 4

affinity

Back 4

the strength of the binding btwn a messenger and its receptor

Front 5

Up regulation

Back 5

an increase in # of receptors compared to "normal" conditions, occurs when cells are exposed to low messenger concentration for a prolonged period.

become more responsive

Front 6

Down regulation

Back 6

a decrease in the # of receptors, occurs when messenger conc. are higher than normal for a prolonged period.

become less responsive

Front 7

agonists

Back 7

Ligands that bind to receptors and produce a biological response

Front 8

antagonists

Back 8

Ligands that bind to receptors but do NOT produce a response.

May actually compete with agonist for the receptor, decreasing the likelihood that the binding of agonist to receptor will occur and bring about a response.

Front 9

Ligand-gated channels

Back 9

Ions channels that open or close in response to the binding of a chemical to a receptor or to the channel

Front 10

Channel-linked receptors

Back 10

a type of ligand-gated channel in which the ligand is a messenger that binds to a receptor.

Front 11

Effects of the target cell in channel-linked receptors

Back 11

1. Ions entering and leaving can change the electrical properties of the cell

2. Entering ions can interact with proteins inside the cell to induce a response such as muscle contraction, secretion, change in metabolism, or altered transport of a substance.

Front 12

Second messenger

Back 12

Calcium enters cell through open channel as a _______ ________ which activates enzymes. Enzymes acts on other proteins.
Will eventually change cell function.

Front 13

Calcium

Back 13

________ is an internal signal.

Front 14

Enzyme-linked receptor

Back 14

Enzyme molecule has a binding site. When enzyme binds it is active, and when enzyme does NOT bind it is inactive.

When enzyme binds it is active, produces ATP through phosphoralation, and product eventually changes cell function.

Front 15

G proteins

Back 15

Involved in transducing chemical signals to response of cells.

Front 16

Calcium
cAMP

Back 16

________ and _____ are secondary messengers that act as internal signals.

Front 17

glial cells

Back 17

Cells of the central nervous system and peripheral nervous system that support and protect neurons; also called neuroglia.

Front 18

nervous system

Back 18

Direct cell-to-cell communication in the ______ ______ generally involves the opening and closing of ion channels, which is very fast and a short duration.

Signals travel quickly and short duration and ideal for controling movement and monitoring the world around us.

Front 19

endocrine system
hormones

Back 19

The ________ system communicates through chemical receptors called hormones, which travel through bloodstream to all cells in body.
________ diffuse into blood

generally communicate by altering protein synthesis or activating G proteins, processes are slower than nervous system.

Front 20

adenylate cyclase

Back 20

G proteins bind to and active this enzyme

Catalyzes the conversion of ATP to cAMP.

Front 21

DAG (diacylglycerol)

Back 21

Membrane phospholipid formed after hydrolysis of PIP2. Functions as a second messenger that activates protein kinase C.

Front 22

Inositol triphosphate (IP3)

Back 22

A second messenger produced by hydrolysis of PIP2. It enters the cytoplasm to open calcium channels in endoplasmic reticulum.

Front 23

Phosphatidyl inositol biphosphate (PIP2)

Back 23

A plasma membrane phospholipid. Hydrolysis produces two molecules, IP3 and DAG, that act as second messengers.

Front 24

cGMP

Back 24

a product of an enzyme-linked receptor, guanlynate cyclase which is commonly associated with G proteins.

A second messenger that is similar to cAMP but it activates protein kinase G.