Test 1 - A&P II

Consider the following events in the nuclear receptor model: (1) Hormone receptor complex binds to DNA. (2) Messenger RNA directs synthesis of specific proteins. (3) Hormone binds to receptors in the nucleus (sometimes in the cytoplasm) (4) Messenger RNA synthesis is activated. (5) Synthesized proteins produce the response of the cell. Which of these events occurs in the nucleus?

1, 3, 4

43. 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.

1, 4, 3, 2

A water-soluble hormone binds to its receptor on the plasma membrane. 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) G-protein subunits separate from the receptor (4) alpha subunit separates from other two subunits (5) G-protein subunits bind to the receptor

5, 2, 3, 4, 1

When a few intracellular mediator molecules activate several enzymes, and each of these activated enzymes activate still other enzymes, the hormone has initiated

A cascade effect

All of the following chemical messengers may be listed in multiple functional classes except

Acetylcholine

Which of the following occurs when a hormone binds to a nuclear receptor?

Activation of mRNA synthesis

Which pattern of hormone secretion, represented by epinephrine, can have dramatic changes in its concentration and circulating levels?

Acute hormone secretion

Hormonal secretion can be regulated by a) the action of a substance other than a hormone b) the nervous system c) other hormones

All of these choices

Most endocrine glands communicate with their target tissues using

Amplitude-modulated signals

How do most water-soluble hormones travel in the bloodstream?

As free hormones

What type of chemical messenger stimulates the cell that originally secreted it?

Autocrine

The role of cAMP when it acts as an intracellular mediator in cells is to

Bind to and activate protein kinase

Which of the following statements is NOT true?

Both the nervous and endocrine systems respond quickly and are active for a long time

How do hormones and target cells recognize one another?

By the presence of specific receptor molecules on the target cells

Which of the following events occurs last?

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

Neurotransmitter

Chemical secreted by presynaptic terminal

Endocrine

Chemical secreted into blood by specialized cells; travels some distance to target tissues

Neuropeptide

Chemicals produced by neurons that function as hormones

Paracrine

Chemicals that act locally on nearby cells

In general, lipid-soluble hormones exhibit which type(s) of hormone secretion pattern(s)?

Chronic and episodic hormone secretion

Which pattern of hormone secretion, exemplified by thyroid hormones, remains relatively constant over long periods of time?

Chronic hormone secretion

Lipid-soluble hormones can be more easily excreted once they have water-soluble molecules added to their structure in a process called

Conjugation

When a hormone binds to a membrane-bound receptor,

Cyclic GMP might be produced to act as an intracellular mediator

David has been feeling tired lately, and after having blood work completed, it shows elevated TSH, low iodine, and low thyroid hormone levels. Predict the possible cause from the choices below.

David may have iodine deficiency that is causing his thyroid to produce too little thyroid hormone

Steroid hormones

Diffuse easily through the plasma membrane

In some forms of diabetes, an insensitivity to insulin seems to be present. This insensitivity could be the result of

Down-regulation

Which pattern of hormone secretion, often observed in steroid reproductive hormones, will fluctuate over a monthly cycle?

Episodic hormone secretion

Which of the following is a regulatory protein associated with membrane-bound receptor molecules?

G protein

The length of time needed to eliminate half of a dose of a hormone is called its

Half life

Hormones are intercellular chemical signals that

Help coordinate growth, development, and reproduction

Secretion of one hormone by the action of another hormone is controlled by _____ stimuli.

Hormonal

Predict which hormone would produce longer lasting effects:

Hormone B, which binds to a nuclear receptor

All of the following are characteristics of hormones except

Hormones interact with any cells in contact with bloodstream

After a meal, blood glucose levels rise and stimulate the release of insulin. What type of stimulation in this example?

Humoral

Parathyroid hormone is released when blood calcium levels decrease. This is an example of control by _____ stimuli.

Humoral

Blood chemistry changes are examples of ____ stimuli; whereas sympathetic nervous system impulses are examples of _____ stimuli for hormone release

Humoral; neural

Receptors for most lipid-soluble hormones are located

In the nucleus or cytoplasm of their target cells

Hormone receptor molecules may be _____ in order to change the target cell's sensitivity to a given hormone.

Increased in number, decreased in number, and chemically altered

Autocrine

Influences same cell type from which it is secreted

Increased testosterone levels reduce the secretion of gonadotropin-releasing hormone from the anterior pituitary. This is an example of

Inhibition of hormone release by hormonal stimuli

A chemical produced in a cell that activates specific processes in response to a hormone interaction with a membrane-bound receptor is referred to as an

Intracellular mediator

Membrane-bound receptor model

Intracellular mediator; G protein; cyclic AMP or cyclic GMP involved; membrane channels may be opened or closed

When a hormone binds to a membrane-bound receptor and activates G proteins,

Ion channels could be opened, IP3 may be activated, cyclic AMP production may be increased, and DAG may be activated

Once a lipid-soluble hormone is conjugated in the liver

It can be more quickly eliminated from the body

Which chemical class of hormone is more likely to need a binding protein for transport in the blood?

Lipid-soluble

Which chemical type of hormone has a longer half-life?

Lipid-soluble

Increasing levels of thyroid hormones decrease TSH levels. This is an example of _____ feedback.

Negative

Most hormones are regulated by

Negative-feedback mechanisms

Sympathetic neurons can serve as _____ stimuli for hormone release from certain endocrine organs

Neural

An intercellular chemical signal that is produced by neurons but functions like a hormone would be called a

Neurohormone

What type of chemical messenger is released from neurons to activate an adjacent cell?

Neurotransmitter

Thyroid hormones normally travel in the blood both free and bound to TH-binding proteins. What would except to see in the blood work of a patient who had a deficiency of TH-binding protein?

Normal free TH levels and low bound TH levels

Receptors for most water-soluble hormones are located

On the plasma membrane of their target cells

What type of chemical messenger will act locally on nearby cells?

Paracrine

______ chemical signals are released by cells and affect other cell types locally without being transported in blood

Paracrine

What type of hormone-receptor action allows insulin to move glucose into cells?

Phosphorylation of intracellular proteins

Which of the following statements regarding hormone transport and distribution is FALSE?

Plasma protein concentration has no influence on free hormone concentration

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

Polypeptides, steroids, and proteins

Up-regulation

Produces an increase in the sensitivity of the target cell to the hormone

Cortisol, a lipid-soluble hormone is released into the blood. Predict what cortisol might do.

Readily diffuses through capillary wall

Hormones with short half-lives

Regulate activities of rapid onset and short duration

The endocrine system

Secretes chemicals that reach their targets through the bloodstream

The release of chemicals from an endocrine or exocrine gland is referred to as

Secretion

In general, the response of target cells to endocrine stimulation is ____ than their response to nervous stimulation.

Slower and more prolonged

Members of which group of hormones are made from cholesterol?

Steroids

Hormones act on specific tissues called

Target tissues

What is it about a cell that identifies it as a target cell for a hormone?

The presence of a receptor specific for that hormone

The half-life of a hormone allows one to determine

The rate at which hormones are eliminated from the body

What do all hormones have in common?

They bind to and interact with a receptor on or in the target cell

All of the following are reasons why some hormones need assistance to travel in the blood except

They cannot dissolve in the blood because they are water-soluble

All of the following are water-soluble hormones except

Thyroid hormone

Secretion of the hormones ____ and _____ exemplify the pattern of chronic hormone secretion

Thyrotropin and thyroxine

Emily is in labor with her first child. The amplitude-modulated system would show her oxytocin levels

To have a strong signal

Phosphodiesterase functions

To inactivate cyclic AMP

In _____, a cell increases the number of hormone receptors and becomes more sensitive to the hormone

Up-regulation

Nuclear receptor model

Used by most lipid-soluble hormones; receptor molecule interacts with DNA; generally observe a latent period; messenger RNA synthesis regulated

Which intracellular mediator is directly activated by the binding of a water-soluble hormone to a membrane receptor?

cGMP