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Flashcards in Hormone Signaling Pathways Deck (83)
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1

Hormones are messenger molecules synthesized and secreted by _______ cells. They are released into ______ or the blood stream and exert their influence by binding receptors on cells of remote target tissues

Endocrine

ECF

2

Hormones binding their receptors results in activation of signal ______ and/or alteration in ______ expression ultimately leading to cell type-specific response

Only a small amount is required to alter cell metabolism because the effect is greatly magnified via signal ________

Transduction; gene

Amplification

3

Multistep process of hormone signaling

Biosynthesis
Storage
Secretion
Transport to target tissue/cells
Recognition and binding to receptors
Activation of signal transduction pathway
Amplification and relay of signal
Cellular response
Degradation

4

4 types of cell signaling

Endocrine
Paracrine
Autocrine
Juxtacrine

5

___________ signaling = signaling molecule released by a cell distant from target cell and transported via blood to target cell

Endocrine

6

___________ signaling = signaling molecule acts on same cell type as secreting cell itself (ex. IL-1)

Autocrine

7

___________ signaling = signaling molecule released by one cell type and diffuses to neighboring target cell of a different type

Paracrine

8

___________ signaling = signaling molecule stays attached to secreting cell and binds receptor on adjacent target cell via connexons (ex. Heparin-binding epidermal growth factor)

Juxtacrine

9

T/f: some signaling molecules participate in more than one type of signaling

True

10

Which of the following is typical of testosterone?

A. Endocrine signaling
B. Paracrine signaling
C. Autocrine signaling
D. Juxtacrine signaling

B. Paracrine signaling

11

Which of the following is typical of epinephrine?

A. Endocrine signaling
B. Paracrine signaling
C. Autocrine signaling
D. Juxtacrine signaling

A. Endocrine signaling

12

Which of the following are hydrophilic hormones?

A. Epinephrine
B. Insulin
C. Steroid hormones
D. Glucagon
E. Thyroid hormone
F. Retinoids

A. Epinephrine
B. Insulin
D. Glucagon

13

Which of the following are lipophilic hormones?

A. Epinephrine
B. Insulin
C. Steroid hormones
D. Glucagon
E. Thyroid hormone
F. Retinoids

C. Steroid hormones
E. Thyroid hormones
F. Retinoids

14

What types of receptors are involved in hydrophilic hormone signaling?

GPCRs
RTKs

15

Lipophilic hormones pass through the plasma membrane of the target cell and bind to either ______ receptors or ______ receptors, either way regulating the transcription of specific genes

Cytoplasmic
Nuclear

16

Describe lipophilic hormone signaling via cytoplasmic receptors

They exist in an inactive complex with HSP90. Upon binding to signal, the HSP dissociates

The hormone receptor complex translocates to nucleus where it binds to a specific DNA sequence called the hormone response element (HRE) in the promoter region of specific genes

17

Describe lipophilic hormone signaling via nuclear receptors

They are already present in the nucleus bound to DNA. The hormone signal activates the complex and allows for interactions with additional proteins

18

Epinephrine is a ______ signal that binds a _______ to cause cellular response

Hydrophilic; GPCR

19

Insulin is a ______ signal that binds a _______ to cause cellular response

Hydrophilic; RTK

20

What is the difference between lipophilic and hydrophilic medications?

Hydrophilic have SHORT half lives (e.g. epinephrine); given at time of need

Lipophilic have long half lives (e.g. oral contraceptives); taken daily

21

GPCR signaling occurs via trimeric G proteins containing 3 subunits (_____, _____, ____)

An inactive G protein has GDP bound to its _____ subunit, which is attached to the other 2 subunits.

To become active, the G protein must exchange its GDP for a GTP, this occurs via the action of _______

The active GTP-bound ____ subunit separates from the other 2 to potentiate activation signal

Alpha, beta, gamma

Alpha

GEF (guanine nucleotide exchange factor)

Alpha

22

For a GPCR to return to its inactive state, the intrinsic GTPase activity of the G protein hydrolyzes its bound GTP to GDP and Pi

This action is accelerated by a ______

GAP (GTPase-activating protein)

23

Describe 4 different GPCR signaling variations: Gs, Gt, Gi, Gq

Gs = stimulates adenylate cyclase, forms cAMP, activates PKA, phosphorylates targets

Gt = stimulates hydrolysis of cGMP by phosphodiesterase

Gi = inhibits adenylate cyclase

Gq = stimulates PLC —> DAG and IP3 —> PKC and calcium/calmodulin

24

Epinephrine binds beta-adrenergic GPCR, activating _____ subunit

What is the physiologic response?

Gs

Relaxation of bronchial and intestinal smooth muscle, contraction of heart muscle, increased breakdown of TAGs in adipose tissue, increased breakdown of glycogen in liver and muscle, increased glycolysis in muscle

[epinephrine is a non-selective agonist of all adrenergic receptors and results in multpile GPCR signaling pathways]

25

Histamine binds ______ GPCR, activating _____ subunit

What is the physiologic response?

Histamine H2; Gs

Bronchoconstriction and symptoms of allergic reaction (e.g. itchy, watery eyes)

26

Epinephrine/Norepinephrine binds alpha-adrenergic GPCR, activating _____ subunit

What is the physiologic response?

Gi

Constriction of smooth muscle

27

Dopamine binds ______ GPCR, activating _____ subunit

What is the physiologic response?

Dopamine D2; Gi

Increased heart rate

28

Acetylcholine binds ______ GPCR, activating _____ subunit

What is the physiologic response?

Muscarinic ACh M3; Gq

Bronchoconstriction and stimulation of salivary glands

29

Light binds ______ GPCR, activating _____ subunit

What is the physiologic response?

Rhodopsin; Gt

Vision

30

RTKs have an extracellular domain that binds the ligand/signaling molecule, a single ________ transmembrane domain, and an intracellular domain with _____ activity

Alpha-helical; tyrosine-kinase