functional organization endocrine system

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1

The endocrine system
A) releases neurotransmitters into ducts.
B) secretes chemicals that reach their targets through the bloodstream.
C) communicates via frequency-modulated signals.
D) contains organs called exocrine glands.
E) is isolated from the nervous system

B) secretes chemicals that reach their targets through the bloodstream

2

Hormones are intercellular chemical signals that
A) are secreted into the external environment where they act.
B) affect only non-hormone producing organs or tissues.
C) help coordinate growth, development and reproduction.
D) alter the sensitivity of neurons to neurotransmitters.
E) operate primarily by positive feedback

C) help coordinate growth, development and reproduction.

3

Most endocrine glands communicate with their target tissues using _____ signals.
A) frequency-modulated
B) amplitude-modulated
C) pitch-modulated
D) resonance-modulated
E) harmonic

B) amplitude-modulated

4

An intercellular chemical signal that is produced by neurons but functions like a hormone
would be called a
A) neuropathogen.
B) neurotransmitter.
C) neurocrine.
D) neurohormone.
E) neurosynthesizer

D) neurohormone

5

Given the following list of organic molecules, which includes hormones? 1. nucleic acid
derivatives 2. polypeptides 3. steroids 4. proteins
A) 1, 3, 4
B) 1, 2, 3
C) 2, 3, 4
D) 1, 2, 3, 4

C) 2, 3, 4

6

Hormonal secretion can be regulated by
A) the action of a substance other than a hormone.
B) the nervous system.
C) other hormones.
D) all of the above.
E) none of the above

D) all of the above.

7

Secretion of TSH (thyroid-stimulating hormone) is regulated by
A) the action of a substance other than a hormone.
B) the nervous system.
C) the action of other hormones.
D) the parasympathetic nervous system.
E) the sympathetic nervous system.

C) the action of other hormones.

8

An example of a situation where the nervous system regulates the rate of hormonal
secretion is when
A) LH stimulates ovulation.
B) increasing blood glucose levels stimulate insulin secretion.
C) TSH stimulates the release of thyroxine.
D) TRH stimulates the release of TSH.
E) sympathetic neurons stimulate the release of epinephrine.

E) sympathetic neurons stimulate the release of epinephrine.

9

Which of the following statements regarding hormone transport and distribution is false?
A) Only free hormones can diffuse through capillary walls and bind to target tissues.
B) Hormones can be transported free in the plasma or bound to plasma proteins.
C) Plasma protein concentration has no influence on free hormone concentration.
D) Hormones bind only to certain types of plasma proteins.
E) All of the statements are true.

C) Plasma protein concentration has no influence

10

The half-life of a hormone allows one to determine
A) the rate of hormone secretion.
B) the identify of a hormone.
C) the rate at which hormones are eliminated from the body.
D) the rate of action of a hormone.
E) the rate of travel

C) the rate at which hormones are eliminated from the body.

11

Receptors for most water-soluble hormones are located
A) in the cytoplasm of their target cells.
B) on the plasma membrane of their target cells.
C) in the lysosomes of their target cells.
D) on the nuclear membrane of their target cells.
E) on the endoplasmic reticulum of their target cells.

B) on the plasma membrane of their target cells.

12

Which of the following is a regulatory protein associated with membrane-bound receptor
molecules?
A) ATP
B) calcium
C) GnRH
D) G protein
E) FSH

D) G protein

13

A hormone binds to its receptor. Arrange the events that follow in correct sequence.
1. alpha subunit-GTP complex alters cell activity
2. GTP binds to the alpha subunit replacing GDP
3. activity of alpha subunit terminated by phosphodiesterase.
4. alpha subunit separates from other two subunits
5. G-protein subunits separate from the receptor
A) 5, 4, 2, 1, 3
B) 4, 2, 1, 3, 5
C) 5, 2, 1, 4, 3
D) 5, 4, 2, 1, 3
E) 3, 4, 1, 2, 5

D) 5, 4, 2, 1, 3

14

Up-regulation
A) results in a decrease in the number of receptor sites in the target cell.
B) produces an increase in the sensitivity of the target cell to the hormone.
C) is found in target cells that maintain a constant level of receptors.
D) produces insensitivity to the hormone in the target tissue.
E) moves the receptors up on the membrane.

B) produces an increase in the sensitivity of the target cell to the hormone.

15

Hormone receptor molecules may be ____ in order to change the target cell's sensitivity
to a given hormone.
A) increased in number
B) decreased in number
C) chemically altered
D) moved
E) A, B, C

E) A, B, C

16

In some forms of diabetes, an insensitivity to insulin seems to be present. This
insensitivity could be the result of
A) up-regulation.
B) over-regulation.
C) down-regulation.
D) a lack of regulation.
E) modulation.

C) down-regulation.

17

Once a hormone is conjugated in the liver
A) its half-life is increased.
B) it can be rapidly eliminated.
C) it can be stored for later use.
D) it is actively transported into cells.
E) it is more slowly eliminated.

B) it can be rapidly eliminated.

18

Hormones with short half-lives
A) are usually lipid-soluble.
B) are maintained at relatively constant levels.
C) have concentrations that increase slowly.
D) regulate activities of delayed onset and long duration.
E) regulate activities of rapid onset and short duration.

E) regulate activities of rapid onset and short duration.

19

How do hormones and target cells recognize one another?
A) by signs
B) by the location of the target cells
C) by the presence of specific receptor molecules on the target cells
D) by the function of the target cells
E) by the location of the hormones

C) by the presence of specific receptor molecules on the target cells

20

The role of cAMP when it acts as an intracellular mediator in cells is to
A) bind to and activate protein kinase.
B) activate genes in the nucleus to produce mRNA.
C) directly activate structural enzymes in the cytoplasm of the target cell.
D) catalyze a cascade reaction that ultimately activates genes on the DNA.
E) control levels of calcium in the cell.

A) bind to and activate protein kinase.

21

When a hormone binds to a membrane–bound receptor,
A) membrane channels are destroyed.
B) cyclic GMP might be produced to act as an intracellular mediator.
C) the nucleus is phosphorylated to prevent G-protein activation.
D) messenger RNA is formed.
E) cellular DNA is altered.

B) cyclic GMP might be produced to act as an intracellular mediator.

22

Phosphodiesterase functions
A) as a membrane-bound receptor molecule.
B) to inactivate cyclic AMP.
C) to attach phosphate groups to enzymes.
D) to combine GTP with cyclic AMP.
E) activates cGMP.

B) to inactivate cyclic AMP.

23

Arrange the following events in proper sequence:
1. The activating hormone interacts with a membrane-bound receptor.
2. Cyclic AMP causes the cell to carry out a function characteristic for that specific hormone.
3. Adenylyl cyclase catalyzes the transformation of ATP to cyclic AMP.
4. Adenylyl cyclase is activated
A) 1, 2, 3, 4
B) 1, 4, 3, 2
C) 3, 4, 2, 1
D) 1, 3, 2, 4
E) 1, 3, 4, 2

B) 1, 4, 3, 2

24

Consider the following events in the intracellular receptor model:
1. Hormone receptor complex binds to DNA.
2. Messenger RNA directs synthesis of specific proteins.
3. Hormone binds to receptors either in cytoplasm or nucleus.
4. Messenger RNA synthesis is activated.
5. Synthesized proteins produce the response of the cell.
Which of these events occurs in the nucleus?
A) 1, 3, 5
B) 1, 3, 4
C) 1, 2, 3
D) 3, 4, 5
E) All events occur in the nucleus

B) 1, 3, 4

25

Steroid hormones
A) bind to membrane receptors.
B) diffuse easily through the plasma membrane.
C) act by activating cAMP.
D) are inactivated by phosphodiesterase.
E) are water soluble.

B) diffuse easily through the plasma membrane.

26

Which of the following occurs when a hormone binds to an intracellular receptor?
A) activation of cyclic AMP
B) activation of mRNA synthesis
C) increased lipid synthesis by ribosomes
D) opens membrane channels.
E) alters membrane permeability.

B) activation of mRNA synthesis

27

When a few intracellular mediator molecules activate several enzymes and each of these
activated enzymes activate still other enzymes, the hormone has initiated
A) a cascade effect.
B) a double loop effect.
C) a protein kinase effect.
D) a cyclic effect.
E) a negative feedback cycle.

A) a cascade effect.

28

Which of the following events occurs last?
A) IP3 (inositol triphosphate) is produced.
B) Epinephrine combines with membrane-bound receptor on smooth muscle cell.
C) Calmodulin binds to the enzyme that phosphorylates myosin and cross-bridges form.
D) IP3 stimulates Ca++ release from the endoplasmic reticulum.
E) Ca++ binds with calmodulin.

C) Calmodulin binds to the enzyme that phosphorylates myosin and cross-bridges form.