Ch. 5 Chemical Receptors

Front 1

gap junctions
chemical messengers

Back 1

All cell in the body use ____ ________ and ________ _________ to communicate with one another

Front 2

connexins

Back 2

Gap junctions link adjacent cells and are formed by plasma membrane proteins called _________.

Front 3

connexons

Back 3

Connexins form __________.

Front 4

connexons

Back 4

These ________ form channels that allow ions and small molecules to pass directly fro one cell to another.

Front 5

couples

Back 5

The movement of ions through gap junctions electrically _______ the cells, such the electrical signals in one cell are directly transmitted to the neighboring cells.

Front 6

gap junctions

Back 6

___ _______ are also found in some glands and btwn some neurons in the brain and retina, where they function in communication.

Front 7

metabolically

Back 7

The movement of small molecules through gap junctions __________ couples the cells, such that one cll can provide necessary nutrients to reach certain bone cells.

Front 8

Paracrines
Autocrines
Cytokines
Neurotransmitters
Hormones
Neurohormones

Back 8

What are the 6 functional classifications of chemical messengers?

Front 9

Paracrines

Back 9

Have local (tissue) effects only.

Ex. histamines

Front 10

Autocrines

Back 10

Local effect on the SAME cell that secretes it.

Front 11

Cytokines

Back 11

Most commonly released by WBCs as part of the immune response to pathogens

Usually act locally on other WBCs, but may travel via the bloodstream to distant targets.

It's recruting other WBCs to attack pathogens

become sensitized to pathogens

Front 12

Neurotransmitters

Back 12

released by neurons at their axons

Act locally on another neuron.

Front 13

Hormones

Back 13

released by endocrine gland cells into the bloodstream, carried to target cells.

Front 14

Neurohormones

Back 14

Messengers released by neurosecretory cells at their axons. Carried by the BLOODSTREAM to target cell.

Target cells are NOT neurons.

Front 15

If they are lipophilic or lipophobic.

Back 15

How are chemical messengers classified? (2)

Front 16

Lipophilic

Back 16

May be lipid soluble

Receptors usually inside the target cell.

Front 17

lipophobic

Back 17

May be water soluble

Receptors usually part of the cell membrane.

Front 18

AA
Amines
Peptides
Steroids
Eicosanoids

Back 18

What are the 5 chemical classifications of messengers?

Front 19

Amino Acids

Back 19

Act as a messenger in the ner. sys.

Lipophobic
Ex. neurotransmitters

Front 20

Amines

Back 20

derived from amino acids
Lipophobic
Ex. dopamine, seratonin, NE are neurotransmitters.
Ex. E and NE are hormones.

Front 21

Peptides

Back 21

multiple AAs bonded together. Length of chain is variable (2-100)

Lipophobic
Ex. many neurotransmitters, hormones, all cytokines.

Front 22

Steroids

Back 22

derived from cholesterol
Lipophilic

Front 23

Eicosanoids

Back 23

derived from fatty acids
Lipophilic
Act as paracrine messengers

Front 24

Signal transduction mechanisms

Back 24

Mechanisms that allow a messenger molecule to act on target cells to change their function.
Messenger binds to receptors on or in the target cell. The receptors then change the activity of enzymes in the cells, changing cell function.

Front 25

Properties of receptors

Back 25

1. show specificity - react only with certain molecules
2. Many types of receptors on or in 1 cell.
3. The more interactions btwn messengers and receptors the greater the effect.

Front 26

messenger concentration
# of receptors present (they change)
receptor affinity (how strong)

Back 26

Interactions effected by :
(3)

Front 27

intercellular receptor function

Back 27

Messenger must be lipophilic
STEROIDS or EICOSANOIDS
Effects on target cells are slow, but it lasts a long time.

Front 28

They control protein synthesis which is a slow process.

Back 28

Why are intercellular receptors' effects slow on target cells?

Front 29

Membrane receptor function

Back 29

Messenger must be lipophobic

Receptors are part of the cell membrane.

Have 3 categories of receptors (Channel-linked, Enzyme-linked, G-protein linked)

Front 30

membrane receptors

Back 30

Channel-linked
Enzyme-linked
G-protein linked

Front 31

Channel-linked receptors

Back 31

Acts as a receptor and a channel
Involved in ion movement across cell membrane.
A gated channel
When receptor interacts w/messenger the channel will open.
Will change cell function
All INTERNAL changes in cell

Front 32

Enzyme-linked receptors

Back 32

Receptor act as both a receptor and an intracellular enzyme
Enzyme function is inactive unless a messenger molecule is attached.

Front 33

G-protein linked receptors

Back 33

Receptor is linked to a group of proteins found in the cell membrane.

The second messenger molecule may be CA++ or cAMP.

Messenger moleucle acting on the receptor activates the _ ________ which in turn act on another protein found in the cell membrane.

Front 34

Long distance communication

Back 34

Utilizes nervous & endocrine systems

Neurons can be over 1 meter in length

used for rapid communication (signal speed up to 100 meter/sec.

Endocrine system secretes hormones often control protein synthesis which is a slow process and it takes time to reach the target cells.
Effects can be long lasting

Front 35

receptor

Back 35

A target cell has certain proteins that specifically recognize and bind the messenger.

Front 36

Paracrines

Back 36

A chemical secreted by a cell that acts on cells in the immediate vicinity.

Front 37

Neurotransmitters

Back 37

chemical released into the interstitial fluid from nervous system cells called neurons.

Released from a specialized protion of the neuron called the axon terminal, which is very close to the target cell.

Front 38

Presynaptic neuron

Back 38

The neuron which conducts an action potential toward a synapse.

Front 39

Postsynaptic neuron

Back 39

The neuron which receives the signal at a synapse.

Front 40

Hormones

Back 40

are chemicals released from endocrine glands into the interstitial fluid, where they can diffuse with the blood.

Travels in blood to get to its target cell.

Bloodstream distributes these to all cells of body, BUT cell only have specific receptors for specific _________.

Front 41

Insulin

Back 41

a hormone secreted by the pancreas and acts on target cells throughout the body to regulate energy metabolism.

Front 42

Cytokines

Back 42

interferons
interleukins

Front 43

Plasma membrane

Back 43

What is the location of receptors on target cells of A.A.s?

Front 44

Plasma membrane

Back 44

What is the location of receptors on target cells of Amines?

Front 45

Plasma membrane

Back 45

What is the location of receptors on target cells of peptide/proteins?

Front 46

cytosol

Back 46

What is the location of receptors on target cells of steroids?

Front 47

cytosol

Back 47

What is the location of receptors on target cells of eicosanoids?

Front 48

neurotransmitters

Back 48

What is the functional classification of AAs?

Front 49

Paracrines
Autocrines
Neurotransmitters
Hormones
Neurohormones

Back 49

What are the functional classification of amines?

Front 50

Paracrines
Autocrines
Neurotransmitters
Hormones
Neurohormones
Cytokines

Back 50

What are the functional classification of peptides/proteins?

Front 51

hormones

Back 51

What is the functional classification of steroids?

Front 52

Paracrines

Back 52

What is the functional classification of eicosanoids?

Front 53

A.A. messengers

Back 53

glutamate
aspertate
glycine
GABA

Front 54

Eicosanoid messengers

Back 54

prostaglandins
leukotrienes
thromoboxanes

Front 55

Catecholamine

Back 55

A type of organic compound that contains a benzene ring structure and an amine group. Dopamine, norepinephrine epinephrine and are _____________.

Front 56

transmitters

Back 56

Dopamine are NE are primarily _________.

Front 57

hormone

Back 57

E is primarily a __________.

Front 58

Amino acid synthesis

Back 58

neurotransmitters must be synthesized in the neuron.
Glycolysis
Pyruvic acid turns into Aceytl CoA
Krebs cycle
neurotransmitters are then transported into vesicles where they are stored until they are released by exocytosis.

Front 59

Amines

Back 59

derived from A.A.s

Front 60

Peptide & protein synthesis

Back 60

Ribosome attached to rough E.R. is where translation occurs. Polypeptide is formed inside the lumen of rough E.R. (prepropeptide)

In lumen of e.r., proteolytic enzymes cleave off A.A.s from prepropeptide, now called propeptide.

In smooth e.r. the propeptide is packaged into transport vesicle.

Vesicle is transported to golgi apparatus.

Golgi apparatus packages propeptide in secretory vesiclefor storage until release is triggered. More A.A.s are cleaved off in golgi apparatus now called a _______.

Front 61

steroid synthesis

Back 61

All _______ are capable of crossing the plasma membrane because they are membrane-permeant, _______ cannot be stored prior to release and instead diffuse out of the cell into the interstitial fluid as soon as they are synthesized.

Are synthesized on demand and released immediately.

Front 62

Eicosanoid synthesis

Back 62

Phospholipase A2 catalyzes the conversion of a membrane phospholipid to arachinodonic acid, the precursor for all eicosanoids. Arachidonic acid is converted into _________ via 2 ways:
1. the cyclooxygenase-dependent pathway leads to the production of prostaglandins, prostacyclins, and thromboxanes
2. lipoxygenase-dependent pathway leads to the production of leukotrienes.

Front 63

half-life

Back 63

the time it take for half of the hormone in the blood to be degradaded.

Front 64

Carrier proteins

Back 64

Messengers can be transported in the nlood either in dissolved form or bound to _______ ________.

Front 65

hydrophilic

Back 65

To be transported in dissolved form, the messenger must be a _________ messenger.

Front 66

albumin

Back 66

carrier protein that is NOT specific and can transport many different hormones.