Chemical Messengers (Topic 6)

Question 1

What two organ systems are primarily used for communication pathways? (2)

Answer 1

the nervous and endocrine systems

Question 2

What are the characteristics of the nervous system? (2)

Answer 2

fast signaling
- response is often short-lived

Question 3

What are the characteristics of the endocrine system? (2)

Answer 3

slower signaling
- response is often long-acting

Question 4

Compare the nervous and endocrine systems: (2)

Answer 4

• share the basic elements found in all homeostatic systems (sensors, integrating center, effectors).
• Both act as transducers

Question 5

What is a transducer? (2)

Answer 5

converts some form of stimulus into an electrochemical message

Question 6

How are chemical messengers characterized? (3)

Answer 6

characterized by:
- what type of cell makes them
- how they get to their target

Question 7

Neurotransmitters (3)

Answer 7

• produced by neurons
• does not enter the blood stream; they travel by diffusion to a neighboring cell

Question 8

Hormones (3)

Answer 8

• produced by endocrine cells
• enters blood stream
• travels to distant places in the body

Question 9

Neurohormone (3)

Answer 9

• made by a neuron
• enters the blood stream

Question 10

Paracrine substance (3)

Answer 10

• produced by local cells
• does not enter the blood stream; they travel by diffusion to a neighboring cell

Question 11

Autocrine substance (3)`

Answer 11

• produced by local cells
• targets itself

Question 12

T/F a substance can serve as more than one type of messenger? (3)

Answer 12

True
ex: norepinephrine
- depends on whether or not it s dropped in the bloodstream

Question 13

What does an agonist do? (4)

Answer 13

binds to a receptor and initiates a physiological response

Question 14

What does an antagonist do? (4)

Answer 14

binds to a receptor but does NOT produce a physiological response (INHIBITS SIGNAL)

Question 15

Does it make sense that lipid-soluble messengers have receptors in the cell? Why or why not? (5) ?

Answer 15

Yes, it can cross the membrane so receptors are in the cell

Question 16

What do receptors bind to? (5)

Answer 16

recognized sequences in the DNA

Question 17

What happens when a receptor binds to a recognized sequence in the DNA? (5)

Answer 17

alters gene expression

Question 18

What are some characteristics of lipid-soluble messengers? (5)

Answer 18

• they are intracellular
• bind to recognized sequences in DNA
• they are slower, more sustained responses compared to membrane receptors
• one receptor can regular many genes

Question 19

What is an example of lipid-soluble messengers? (5)

Answer 19

Steroid hormones

Question 20

Where are water-soluble messengers found? (6)

Answer 20

In the membrane

Question 21

What are the four types of water-soluble messenger receptors? (6)

Answer 21

1. ligand-gated ion channel
2. receptor tyrosine kinase
3. coupled to janus kinase
4. coupled to G-protein

Question 22

What is the most common water-soluble messenger receptor? (6)

Answer 22

coupled to G-protein

Question 23

What happens in G-protein receptors? (6)

Answer 23

GDP leaves and GTP comes in

Question 24

Steps of adenylyl cyclase and cyclic AMP (9)

Answer 24

Water-soluble (first) messenger binds to receptor -> gene expression is altered -> GDP leaves and GTP binds -> alpha subunit is now active and slides along the membrane to activate another protein -> ATP converts to cAMP -> second messenger binds to cAMP dependent protein kinase to make it active -> active kinases phosphorylates other proteins and those activate other pathways that lead to -> cellular response

Question 25

G-protein + cAMP allows for what? (10)

Answer 25

for 100x amplification

Question 26

“amplification cascade” is crucial for what? (10)

Answer 26

crucial for fast complex responses

Question 27

Example of signal amplification (10)

Answer 27

binding of 1 molecule of epinephrine can cause the liver to release 108 glucose