Chapter 5 Lecture Slides

Question 1

what are the four basic methods of cell-to-cell communication that our bodies use, and are they local or long-distance? (5)

Answer 1

• gap junctions (local)
• contact-dependent signaling (local)
• autocrine and paracrine (local)
• endocrine uses hormones (long-distance)
• signaling pathways (long distance)

Question 2

what is autocrine signaling?

Answer 2

source = target

Question 3

source = target ?

Answer 3

autocrine signaling

Question 4

what is paracrine signaling?

Answer 4

source does not equal target, but immediate vicinity

Question 5

signal is secreted into the interstitial fluid and diffuses to nearby cells in the same tissue

Answer 5

paracrine

Question 6

what is an example of paracrine signaling?

Answer 6

endothelial cells of the vascular system talk to neighboring tissue cells

Question 7

where is the signal secreted in paracrine signaling? what happens next?

Answer 7

into the ISF and diffuses to nearby cells in the same tissue

Question 8

redding at a scratch is due to release of?

Answer 8

paracrine molecule histamine

Question 9

how does the endocrine system communicate?

Answer 9

hormones

Question 10

hormones are used by ?

Answer 10

endocrine system

Question 11

describe endocrine signaling?

Answer 11

source isn’t the target, far away

Question 12

hormones are… (2)

Answer 12

1. chemical messengers made by gland cells
2. secreted into the bloodstream to act on target cells in another tissue or organ

Question 13

how does the nervous system communicate?

Answer 13

combo of electrical and chemical signals

Question 14

what provides the specificity in a signaling pathway?

Answer 14

receptors

Question 15

where may the receptor be located, depending on the ligand?

Answer 15

on or in the target cell

Question 16

steroid hormones: hydrophilic or hydrophobic?

Answer 16

hydrophobic

Question 17

steroid hormones: lipophilic or lipophobic?

Answer 17

lipophilic

Question 18

how are steroid hormones made?

Answer 18

from cholesterol and on demand

Question 19

how are steroid-based hormones transported in the blood?

Answer 19

bound to carrier proteins

Question 20

why do steroid-based hormones have to be bound to a carrier protein while in circulation?

Answer 20

because they are hydrophobic!

Question 21

what does amphipathic mean?

Answer 21

hydrophilic and hydrophobic side

Question 22

steroid hormones bind to receptors where? why? (2)

Answer 22

• in the cytoplasm. they are lipophilic/hydrophobic
• bind to HREs

Question 23

what are HREs?

Answer 23

hormone responsive elements. DNA sequences that, when bound by their specific ligand/receptor complex, turn gene expression on or up

Question 24

are lipophilic hormones fast acting?

Answer 24

no. they use intracellular receptors that initiate gene transcription to make mRNA

Question 25

describe the half-life of a hydrophobic chemical messenger. why? pros and cons?

Answer 25

relatively long. carrier provides protection from removal, and acts as a type of storage.

increased protection / survival but only 1% is free to act so it limits the hormone’s effect