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