Anatomy & Physiology Unit 9: The Endocrine System

Aldosterone is produced by the

adrenal cortex.

Glucocorticoids are produced by the

adrenal medulla.

Glucagon is produced by

alpha cells of pancreatic islets.

Hormone release stops once

an appropriate level in the blood is reached.

Upon the release of renin,

angiotensin II is produced and stimulates vasoconstriction and the release of aldosterone.

Insulin is produced by

beta cells of pancreatic islets.

Humoral stimuli of endocrine glands change blood levels of

certain ions to stimulate hormone release. Humoral indicates various body fluids such as blood and bile.

Parathyroid hormone and calcitonin are produced in response to

changing levels of blood calcium levels.

Insulin is produced in response to

changing levels of blood glucose.

Name the different types of intercellular communication.

1) Direct communication 2) Paracrine communication 3) Autocrine communication 4) Endocrine communication Direct communication occurs through the exchange of ions and molecules between adjacent cells across gap junctions. This type of communication can only happen between two cells of the same type. Paracrine communication is signaling between cells within a single tissue. It can be defined as the signaling pathway in which cells communicate over a relatively short distance. The important feature of such a signaling pathway is that it allows the cell to be in coordination with other cells neighboring it. Autocrine communication is when chemical messages affect the same cells that secrete them. The most important example of autocrine signaling is apoptosis, defined as programmed cell death. Another example would include the prostaglandins secreted by smooth muscle cells that cause those same cells to contract. Endocrine communication occurs when endocrine cells release chemicals that are transported over a long distance in the bloodstream. Endocrine signaling alters the metabolic activities of many organs.

What are the three major classes of hormones?

1) protein/peptide derived 2) steroid/lipid derived 3) amine/amino acid derived Protein hormones (or polypeptide hormones) are made from chains of amino acids. An example is ADH which decreases blood pressure. Steroid hormones are derived from lipids. Reproductive hormones like testosterone and estrogen are steroid hormones. Amine hormones are derived from amino acids. Epinephrine, which helps regulate the fight-or-flight response, is an amine hormone.

Cells secrete hormones into

extracellular fluids.

Cushing's syndrome

A caused by prolonged exposure to high levels of cortisol. The patient will present with a round face, a hump on the upper back, red marks on the abdomen, high blood pressure, hyperglycemia, weakening of the bones, and depression.

What is Graves' disease?

A condition caused by hyperthyroidism. It results in increased metabolism, heat intolerance, rapid heartbeat, weight loss, and exophthalmos.

What is myxedema?

A condition caused by hypothyroidism in adults. It results in physical and mental sluggishness.

What is cretinism?

A condition of severely stunted physical and mental growth due to untreated congenital deficiency of thyroid hormones (congenital hypothyroidism) usually due to maternal hypothyroidism. It results in dwarfism during childhood.

Hyperaldosteronism

A condition that may result from an ACTH-releasing tumor. Excess water and sodium are retained leading to high blood pressure and edema.

Addison's disease

A condition that occurs when the adrenal cortex does not produce enough cortisol and aldosterone. Bronze skin tone, low blood pressure, high potassium ion levels, muscles are weak, and susceptibility to infection.

Pineal gland

A gland found in the third ventricle of the brain. It secretes melatonin, which helps to establish the body's wake and sleep cycles. It is also believed to coordinate the hormones of fertility in humans.

What is thyroid-stimulating hormone (TSH)?

A hormone of the anterior pituitary gland that influences growth and activity of the thyroid gland.

What is adrenocorticotropic hormone (ACTH)?

A hormone of the anterior pituitary gland that regulates endocrine activity of the adrenal cortex.

What is prolactin (PRL)?

A hormone of the anterior pituitary gland that stimulates and maintains milk production following childbirth. Its function in males is unknown.

What is follicle-stimulating hormone (FSH)?

A hormone of the anterior pituitary gland that stimulates follicle development in ovaries and sperm development in testes.

What is luteinizing hormone (LH)?

A hormone of the anterior pituitary gland that triggers ovulation of an egg in females and testosterone production in males.

Progesterone

A hormone of the ovaries that acts with estrogen to bring about the menstrual cycle. It helps in the implantation of an embryo in the uterus and prepare breasts for lactation.

Parathyroid hormone (PTH)

A hormone of the parathyroid glands that stimulate osteoclasts to remove calcium from bone, stimulate the kidneys and intestine to absorb more calcium, and raise calcium levels in the blood.

Antidiuretic hormone (ADH)

A hormone of the posterior pituitary gland that inhibits urine production by promoting water readbsorption by the kidneys. In large amounts, it causes vasoconstriction leading to increased blood pressure. It is also known as a vasopressin.

Oxytocin

A hormone of the posterior pituitary gland that stimulates contractions of the uterus during labor, sexual relations, and breastfeeding. It also causes milk ejection in a nursing woman.

Calcitonin (CT)

A hormone of the thyroid gland that decreases blood calcium levels by causing its deposition on bones. Therefore, it is antagonistic to parathyroid hormone. This hormone is produced by parafollicular cells.

Mineralocorticoids (aldosterone)

A hormone produced by the outer adrenal cortex (zona glomerolosa). Its function is to regulate the mineral content in blood and the water and electrolyte balance. Aldosterone reabsorbs sodium ions from the kidneys and excretes potassium ions in return. With an increase in sodium, there is also an increase in water, blood volume, and blood pressure. Its target organ is the kidney.

Testosterone

A hormone secreted by the interstitial tissue of the testes; responsible for male secondary sex characteristics, promotes growth and maturation of male reproductive system, and is required for sperm cell production.

What is the thyroid hormone?

A major metabolic hormone of the thyroid gland. It is composed of two active iodine-containing hormones: thyroxine (T4) and Triiodothyronine (T3).

Adrenal Glands

A pair of endocrine glands that sit on top of the kidneys. There are two regions: the adrenal cortex and adrenal medulla.

Estrogen

A sex hormone, secreted in greater amounts by females than by males. It stimulates the development of secondary female sex characteristics and helps to mature female reproductive organs. Along with progesterone, estrogen also promotes breast development and regulate menstrual cycles.

What hormone released into the blood by the posterior pituitary would reduce the amount of urine that is formed? A) antidiuretic hormone (ADH) B) cortisol C) thyroid-stimulating hormone (TSH) D) oxytocin

A. Antidiuretic hormone (ADH) targets the kidneys and modulates how much water is lost in the urine.

The amplification of a signal from a water-soluble hormone is achieved through an increase in _______. A) cAMP in the cytoplasm B) adenylate cyclase in the plasma membrane C) water-soluble hormone in the blood D) plasma membrane receptors E) phosphodiesterase in the cytoplasm

A. Many cAMP can be generated as a second messenger to amplify the signal in response to hormone binding.

What is the role of activated protein kinases? A) Phosphorylate proteins. B) Phosphorylate ADP to ATP. C) Degrade cAMP to AMP. D) Convert ATP to cAMP by phosphorylation. E) Activate adenylate cyclase.

A. Phosphorylation can activate different proteins causing the response of the cell to water-soluble hormone.

Which of the following occurs in situations where different hormones produce the same effects at the same target cell and their combined effects are amplified? A) synergism B) antagonism C) permissiveness D) summation

A. Synergism occurs when more than one hormone produces the same effects at the target cell and their combined effects are amplified. For example, let's say both hormone "A" and hormone "B" cause the liver to release glucose into the blood. When they act together, the amount of glucose released might be 150% of what is released if each hormone acts independently.

Where is antidiuretic hormone (ADH), also known as vasopressin, synthesized? A) hypothalamus B) kidney C) anterior pituitary D) posterior pituitary

A. Yes, ADH is synthesized mainly in the supraoptic nucleus of the hypothalamus. It is stored in the posterior pituitary in axon terminals.

What keeps intracellular receptors from binding to DNA before a hormone binds to the receptor? A) chaperone proteins (chaperonins) B) transcription factors C) Receptors can't enter the nucleus until the hormone is bound to it.

A. Yes, each receptor has two binding sites. The chaperone protein blocks the DNA binding site until a hormone binds at the hormone binding site.

What is the mechanism of action of lipid-soluble hormones? A) activation of genes, which increases protein synthesis in the cell B) phosphorylation of intracellular proteins C) increasing protein kinases

A. Yes, lipid-soluble hormones diffuse into the nucleus or they diffuse into the cytoplasm and then move into the nucleus, where they affect transcription and translation.

What is the most important regulatory factor controlling the circulating levels of thyroid hormone? A) negative feedback B) thyroid-stimulating hormone (TSH) C) thyrotropin-releasing hormone (TRH) D) a circadian rhythm of release

A. Yes, negative feedback controls the levels of circulating thyroid hormone. If levels are high, negative feedback will decrease thyroid-stimulating hormone (TSH) (and thyrotropin-releasing hormone (TRH) to some degree), thus decreasing the thyroid hormones.

What is the function of the ventral hypothalamic neurons? A) control secretion of thyroid stimulating hormone (TSH) B) control secretion of antidiuretic hormone (ADH) C) control secretion of oxytocin D) control secretion of thyroid hormones

A. Yes, neurohormones from the ventral hypothalamic neurons, known as releasing (RH) and inhibiting (IH) hormones, control the release of anterior pituitary hormones such as adrenocorticotropic hormone (ACTH) and TSH.

Which of the following hormones is regulated by a neuroendocrine ("letdown") reflex? A) oxytocin B) cortisol C) antidiuretic hormone (ADH)

A. Yes, suckling of the infant (or stretching of the uterus) increases release of oxytocin, which causes the milk let-down effect (or increased uterine contractions).

What hormone stimulates the kidneys to reabsorb more sodium?

Aldosterone

Insulin

Allows glucose to cross plasma membranes into cells from beta cells.

Glucagon

Allows glucose to enter the blood from alpha cells.

What happens during the second-messenger system?

Amine or peptide-derived hormones are water-soluble and thus polar so they cannot enter the cell. They must bind to a cell surface receptor instead to activate or deactivate an existing protein within the cell. This bindingcatalyzes a reaction that produces a second-messenger molecule such as cAMP. cAMP oversees additional intracellular changes to promote a specific and quick response.

Thyroid Gland

An endocrine gland that surrounds the trachea at the base of the throat. It consists of two lobes and a connecting isthmus. It produces two hormones: thyroid hormone and calcitonin.

Damage of which of the following brain structures could cause central diabetes insipidus? A) Cerebrum B) Hypothalamus C) Pons D) Thymus

B

Amino acid derived hormones are water soluble. Which of the following hormones is not an amino acid-derived hormone? A) Epinephrine B) Estradiol C) Norepinephrine D) Thyroxine

B. Estradiol is a lipid-derived hormone not an amino acid derived hormone. Thus, it is lipid soluble and a steroid.

The various hormones secreted by the anterior pituitary that regulate the secretion of hormones from other endocrine organs are called __________. A) statins B) tropins C) steroids D) amines

B. Four of the six anterior pituitary hormones—thyroid-stimulating hormone (thyrotropin), adrenocorticotropic hormone (corticotropin), follicle-stimulating hormone and luteinizing hormone (gonadotropins)—are tropins (tropic hormones) that regulate the secretory action of other endocrine glands.

A patient is being treated by her urologist for a fourth episode of kidney stones. Analysis of the stones shows that they are composed of calcium oxalate. The urologist orders an assay of which hormone? A) Glucagon B) Parathyroid hormone (PTH) C) Aldosterone D) Cortisol

B. Inappropriately high levels of PTH may result in excess calcium in the blood, which might precipitate in the urine. The result is renal lithalsas, or kidney stones.

Which of the following statements about lipid-derived hormones is FALSE? A) Lipid derived hormones are not soluble in water B) Lipid derived hormones are polar molecules C) Lipid derived hormones include steroids D) Lipid derived hormones circulate in the bloodstream longer than water-soluble hormones

B. Lipid-derived hormones are not soluble in water and therefore are not polar molecules but instead nonpolar molecules that dissolve in lipids.

Which gland secretes the most important hormone controlling calcium balance in the blood? A) thymus B) parathyroid C) thyroid D) adrenal

B. Parathyroid hormone (PTH) is the single most important hormone controlling calcium balance in the blood. Falling blood Ca2+ levels trigger PTH release, and rising blood Ca2+ levels inhibit its release. PTH promotes bone resorption to release Ca2+ into the blood, inhibits excretion of Ca2+ in the urine, and stimulates the synthesis of Calcitriol, which in turn increases absorption of Ca2+ from our diet.

Which of the following must a peptide hormone have in order to initiate a signal cascade within a cell? A) Peptide hormones need a carrier protein to initiate a single cascade B) Peptide hormones need membrane receptors in order to initiate a single cascade C) Peptide hormones need a gated ion channel to enter a cell to initiate a single cascade D) Peptide hormones diffuse across a cell membrane to bind to intracellular hormone receptors to initiate a single cascade

B. Peptide hormones are water-soluble and therefore cannot pass through a cell membrane and must bind to receptors on the cell surface in order to send signals via a single cascade.

Water-soluble hormones affect target cells by binding to __________. A) protein kinases B) plasma membrane receptors C) cAMP D) cytoplasmic receptors E) adenylate cyclase

B. Water-soluble hormones bind to specific receptors in the plasma membrane, whereas steroid hormones bind to cytoplasmic receptors.

What tropic hormone stimulates cortisol from the adrenal gland? A) thyroid stimulating hormone (TSH) B) adrenocorticotropic hormone (ACTH) C) growth hormone (GH) D) luteinizing hormone (LH) and follicle stimulating hormone (FSH)

B. Yes, ACTH stimulates the adrenal cortex to produce cortisol. Stress and ACTH are the main stimuli for cortisol.

Insulin-like growth factors (IGFs) are intermediary hormones stimulated by which of the following hormones? A) prolactin (PRL) B) GH (growth hormone) C) oxytocin D) thyroid hormones

B. Yes, GH stimulates IGFs from the liver. IGFs are required for the growth effect of GH on bone and skin.

After a lipid-soluble hormone is bound to its intracellular receptor, what does the hormone complex do? A) directly alters protein synthesis at the ribosome B) phosphorylates a protein C) acts as a transcription factor and binds to DNA, activating a gene D) activates a protein kinase

C

Your patient has been diagnosed with Type I diabetes mellitus, and you are explaining how to administer insulin. Your patient states, "I don't want to do this. My brother-in-law has diabetes, and he just takes a pill and watches what he eats." What is your best response? A) "Great. Maybe your relative can give you some tips on how to manage your condition." B) "I'll ask the doctor if you can try an oral pill and a low carbohydrate diet before using insulin." C) "Your relative may have Type II diabetes. People with that condition can make insulin, but their cells don't respond to it properly. Your pancreas doesn't manufacture insulin." D) "Perhaps you can switch to pills and a special diet once your diabetes is under control."

C

Your patient has been admitted to the intensive care unit with a severe head injury. As you monitor his urine output, you find that it has fallen sharply. Lab tests indicate that his serum osmolality is lower than normal (i.e., his plasma is too dilute). What should you suspect? A) Thyroid-stimulating hormone (TSH) B) Prolactin C) Syndrome of inappropriate antidiuretic hormone (SIADH) D) Parathyroid hormone (PTH)

C. Antidiuretic hormone (ADH) is released from the posterior pituitary in response to rising serum osmolality. This causes the kidneys to preserve water, helping to restore normal solute/water balance. Your patient is retaining water despite a dilute plasma, suggesting that he is making "inappropriate" ADH. This problem may occur after head trauma or in some cancers.

Cyclic AMP is degraded by __________. A) AMP B) adenylate cyclase C) phosphodiesterase D) G proteins E) protein kinase

C. Phosphodiesterase degrades cyclic AMP into AMP.

How do endocrine hormones reach their target cells? A) Hormones are released at synapses adjacent to target cells. B) Ducts transport hormones directly to target cells. C) Hormones are transported through the blood stream to target cells. D) Hormones are produced by endocrine cells that are adjacent to target cells. E) Hormones travel through the lymphatic system to target cells.

C. The blood stream allows hormones to be distributed throughout the body.

Which of the following hormones has intracellular receptors? A) insulin B) epinephrine C) cortisol

C. Yes, cortisol is one of the lipid-soluble steroid hormones. Thyroid hormones are also lipid soluble.

Which hormone's receptor is always bound to DNA, even when the receptor is empty? A) insulin B) cortisol C) thyroid hormone

C. Yes, thyroid hormones are lipid soluble and their receptors are bound to the response elements of the DNA.

Lowers blood calcium levels.

Calcitonin

What hormone reduces blood calcium levels, and which endocrine gland produces this hormone?

Calcitonin is a hormone that reduces blood calcium levels and is produced by the parafollicular cells (commonly known as C-cells) of the thyroid gland. Calcitonin is involved in helping to regulate levels of calcium and phosphate in the blood, opposing the action of parathyroid hormone.

What are hormones?

Chemical messengers that are released into the blood.

Which of the following pairs correctly matches the adrenal gland structure with the class of hormones it produces? A) zona fasciculata: catecholemines B) zona reticularis: aldosterone C) medulla: glucocorticoids D) zona glomerulosa: mineralocorticoids

D

Which of these conditions would promote aldosterone release from the adrenal glands? A) Blood potassium levels fall. B) The body becomes parasympathetically activated. C) An increase in blood pressure is sensed in the heart. D) A drop in blood pressure is sensed in the kidney.

D. A drop in blood pressure would cause the kidney to release renin, a hormone that will eventually promote the release of aldosterone from the zona glomerulosa of the adrenal cortex.

Which hormone aids in water resorption? A) thyroid hormone B) adrenocorticotropic hormone C) parathyroid hormone D) antidiuretic hormone

D. Antidiuretic hormone (ADH) stimulates the kidney tubules to reabsorb water.

Hypocalcemia could be caused by the ______. A) apoptosis of parathyroid cells B) failure of osteoclasts to respond to PTH (parathyroid hormone/parathormone) C) malfunction of the parathormone receptors in kidney tubule cells D) All of the listed responses are correct.

D. Parathyroid hormone (parathormone) is secreted in response to hypocalcemia. It functions to stimulate osteoclast activity, enhances the reabsorption of calcium by the kidneys, and increases absorption of calcium ions by the intestinal mucosal cells.

Which hormone stimulates mammary glands to produce milk in nursing mothers? A) follicle-stimulating hormone B) adrenocorticotropic hormone C) oxytocin D) prolactin

D. Prolactin stimulates the mammary glands of the nursing mother to produce milk. After birth, the infant's suckling stimulates release of prolactin-releasing factors in the mother, encouraging continued milk production.

As the adrenal gland releases glucocorticoids, which of the following effects may be observed?

Decrease in immune system function Lipid breakdown in the liver will increase Increased blood levels of amino acids Increased blood glucose levels With long-term stress, the glucocorticoid hormones, chiefly cortisol, are instrumental in the body. The primary targets include the liver, resulting in increased gluconeogenesis and increased catabolism of lipids and proteins. In larger amounts, the depression of the immune system can result.

What are the two mechanisms in which hormones act?

Direct gene activation and second messenger system.

Raises blood glucose levels, constricts vessels, increases metabolic rate.

Epinephrine and norepinephrine.

What are the hormones of the adrenal medulla?

Epinephrine and norepinephrine. These hormones prepare the body to deal with short-term stress by increasing heart rate, blood pressure, and blood glucose levels. They also dilate small passage ways of the lungs.

Which gonadal hormone causes a young girl's reproductive organs to mature at puberty, estrogen or progesterone?

Estrogen

What are the two important differences between exocrine and endocrine glands?

Exocrine glands release their non-hormonal products to an epithelial surface via a duct.

Up-regulation involves the loss of receptors and prevents the target cells from overreacting to persistently high hormone levels. True False

False. Prolonged exposure to high hormone concentrations would result in down-regulation (not up-regulation), which involves a decrease in the number of receptors for that hormone. Down-regulation desensitizes the target cells, so they respond less vigorously to hormonal stimulation, preventing them from overreacting to persistently high hormone levels.

What are the two gonadotropic hormones of the anterior pituitary gland?

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

Acromegaly results from hypersecretion of

GH during adulthood.

Ovaries

Glands that produce egg cells and two groups of steroid hormone, estrogen and progesterone.

What are goiters?

Goiters are an enlargement of the thyroid gland due to a lack of iodine. Salt is normally iodized to prevent this condition.

What two pituitary hormones affect non-endocrine targets?

Growth hormone and prolactin.

In the elderly, the decline in levels of which hormone is associated with muscle atrophy? With osteoporosis in women?

Growth hormone decline results in muscle atrophy, estrogen decline leads to osteoporosis.

Adam is excreting huge amounts of urine. He has an endocrine system problem, but it is not diabetes mellitus, which has a similar sign. What is the possible problem?

He has diabetes insipidus. During the day, the kidneys filter all the blood in the body many times. Normally, most of the water is reabsorbed, and only a small amount of concentrated urine is excreted. DI occurs when the kidneys cannot concentrate the urine normally, and a large amount of dilute urine is excreted. The amount of water excreted in the urine is controlled by antidiuretic hormone (ADH). ADH is also called vasopressin. ADH is produced in a part of the brain called the hypothalamus. It is then stored and released from the pituitary gland. DI caused by a lack of ADH is called central diabetes insipidus. When DI is caused by a failure of the kidneys to respond to ADH, the condition is called nephrogenic diabetes insipidus. Nephrogenic means related to the kidney.

Mrs. Greene's husband has suffered a heart attack and is hospitalized. Would you expect her blood glucose levels to be elevated , normal, or lower than normal? Why?

Her blood glucose levels would be elevated because she is stressed. When the body is stressed, both glucocorticoids (adrenal cortical hormones) and epinephrine and norepinephrine (adrenal medullary hormones) are produced in increased amounts. Both sets of hormones produce a rise in blood glucose levels.

What are the three ways in which endocrine glands are stimulated to secrete their hormone?

Hormonal, humoral, and neural.

Glucocorticoids (including cortisone and cortisol)

Hormones produced by the middle layer of the adrenal cortex (zona fasciculata). They promote normal cell metabolism and help resist long-term stressors. These hormones are released in response to increased blood levels of ACTH. Cortisol increases glucose and energy through glycogenolysis and gluconeogenesis.

What are tropic hormones?

Hormones that have other endocrine glands as their targets.

The long-term and short-term stress responses vary in their mechanisms.

In the short-term response, stressful stimuli target the hypothalamus, which activates the sympathetic nervous system, ultimately impacting the adrenal medulla. The adrenal medulla releases the catecholamine hormones - epinephrine and norepinephrine - which result in many of the effects associated with the "fight or flight" mechanism. In the long-term response, stressors to the hypothalamus cause the release of corticotropin-releasing hormone, which targets the anterior pituitary gland. Adrenocorticotropic hormone travels in the blood and targets the adrenal cortex, resulting in the production of mineralocorticoids and glucocorticoids. The mineralocorticoids impact the kidney with increased sodium and water retention, while the glucocorticoids target the liver to increase production of glucose from fats and proteins, or mobilize them for energy.

Aldosterone

Increased sodium and water absorption.

Cortisol

Increases metabolic effects from the liver.

Insulin and glucagon are both pancreatic hormones. Which stimulates cellular uptake of glucose?

Insulin stimulates cellular uptake of glucose.

Lowers blood glucose levels.

Insulin.

Why is iodine important to proper thyroid gland function?

Iodine is an essential mineral commonly found in seafood. Your thyroid gland uses it to make thyroid hormones, which help control growth, repair damaged cells and support a healthy metabolism.

Why is cAMP called a second messenger?

It helps promote a specific response for the initial messenger.

What is growth hormone?

It is a general metabolic hormone of the anterior pituitary gland. This hormone affects the growth of skeletal muscles and long bones, plays a role in determining final body size, causes amino acids to be build into proteins and fats to be broken down for a source of energy.

Both the anterior pituitary and the posterior pituitary release hormones, but the posterior pituitary is not an endocrine gland, what is it?

It is actually an extension of / contains nerve cells from the hypothalamus. Where the anterior pituitary is actually a gland that produces hormones. The posterior pituitary doesn't produce hormones, but only stores and releases hormones produced by the hypothalamus.

What is the endocrine function of the placenta?

It produces hormones that maintain the pregnancy. Some hormones play a part in the delivery of the baby. In addition, it produces human chorionic gonadotropin (hCG) as well as estrogen, progesterone, and other hormones.

Thymosin

Its primary function is to stimulate the production of T cells, which are an important part of the immune system. Thymosin also assists in the development of B cells to plasma cells to produce antibodies.

Thymus Gland

Located posterior to the sternum. It is largest in infants and children and slowly shrinks as they grow. It produces thymosin, a hormone that matures some types of white blood cells and is important in developing the immune system.

Stimulates testes and ovaries to produce their hormones.

Luteinizing hormone.

Testes

Male gonads that produce sperm and androgens, such as testosterone.

What hormone is called the sleep hormone, and which endocrine gland produces it?

Melatonin, produced by the pineal gland.

Involved in daily and seasonal biological rhythms.

Melatonin.

Promotes reabsorption of sodium by the kidneys.

Mineralocorticoids.

FSH and LH are examples of

gonadotropic hormones, which target the ovaries or testes.

Gigantism results from hypersecretion of

growth hormone (GH) during childhood.

Pituitary dwarfism results from hyposecretion of

growth hormone (GH) during childhood.

Hormonal release is regulated by releasing and inhibiting hormones produced by the

hypothalamus.

Hormonal stimuli of endocrine glands are the

most common stimuli and are activated by other hormones.

Hormone levels in the blood are mostly maintained by

negative feedback.

Neural stimuli of endocrine glands create

nerve impulses to stimulate hormone release. Most are under the control of the sympathetic nervous system.

Norepinephrine and epinephrine are released by

neural stimuli and come from the adrenal medulla.

Most endocrine organs operate smoothly until

old age. Menopause is brought about by lack of efficiency of the ovaries. Problems associated with reduced estrogen are common. Growth hormone production declines with age as with many endocrine glands.

An enzyme that degrades second messengers like cAMP or cGMP is

phosphodiesterase.

Human chorionic gonadotropin (hCG) is produced by the

placenta.

Overeating, or

polyphagia, is a sign associated with diabetes mellitus.

Overproduction of urine, or

polyuria, is a sign of diabetes mellitus.

Hormones are produced by

specialized cells called endocrine glands.

Target cells must have .

specific protein receptors.

Direct gene activation is performed by

steroid/lipid-derived hormones. These hormones travel through the blood coated with a protein called albumin. Since these hormones are lipid-soluble they can easily pass through lipid bilayer membrane and attach to the receptors on the inside of the cell. They alter the DNA directly to make new proteins. This is a slow process.

Hormones affect only certain tissues or organs called

target cells or target organs.

Blood transfers hormones to

target sites. These hormones regulate the activity of other cells.

Anterior pituitary hormones travel to target glands, such as

the thyroid gland, to prompt the release of a particular hormone, such as thyroid hormone.

Catecholamines are produced by the

thymus.

T4 is secreted by

thyriod follicles.

Steroid/Lipid Derived Hormones

Most lipid hormones are derived from cholesterol and thus are structurally similar to it. The primary class of lipid hormones in humans is the steroid hormones. Chemically, these hormones are usually ketones or alcohols; their chemical names will end in "-ol" for alcohols or "-one" for ketones. Examples of steroid hormones include estradiol, which is an estrogen, or female sex hormone, and testosterone, which is an androgen, or male sex hormone. These two hormones are released by the female and male reproductive organs, respectively. Other steroid hormones include aldosterone and cortisol, which are released by the adrenal glands along with some other types of androgens. Steroid hormones are insoluble in water, and they are transported by transport proteins in blood. As a result, they remain in circulation longer than peptide hormones. For example, cortisol has a half-life of 60 to 90 minutes, while epinephrine, an amino acid derived-hormone, has a half-life of approximately one minute.

Failure of which endocrine organs leads to menopause in women?

Ovaries

Stimulates contraction of the uterus and the milk reflex.

Oxytocin

What two hormones are secreted by the posterior pituitary?

Oxytocin and Antidiuretic hormone (ADH).

What two hormones are produced by the hypothalamus?

Oxytocin and Antidiuretic hormone. These hormones are transported to neurosecretory cells of the posterior pituitary. The posterior pituitary is not strictly an endocrine gland, but does release hormones.

What hormone increases blood calcium levels, and which endocrine gland produces this hormone?

Parathyroid hormone, produced by the parathyroid glands, regulates calcium levels in the blood, largely by increasing the levels when they are too low.

What are the major endocrine organs?

Pituitary gland Thyroid gland Parathyroid glands Adrenal glands Pineal gland Thymus gland Pancreas Gonads (ovaries and testes) Hypothalamus

What temporary organ produces the same hormones as the ovaries?

Placenta

Weak Androgens

Produced by the inner layer of the adrenal cortex (zona reticularis). Secretes androgens (male sex hormones) and some estrogens (female sex hormones) are also formed. One example of a hormone produced by the zona reticularis is DHEA. This hormone helps make male and female sex hormones within the body.

What are the six anterior pituitary hormones?

Prolactin, growth hormone, follicle-stimulating hormone, luteinizing hormone, thyroid-stimulating hormone, and adrenocorticotrophic hormone.

What is the function of the endocrine system?

Reproduction, growth and development, mobilization of body defenses, maintenance of homeostasis, and regulation of metabolism.

Which group of hormones produced by the adrenal cortex has some of the same effects as the hormones of the ovaries and the testes?

Sex hormones. Mostly androgens (male sex hormones).

What happens during direct gene activation?

Steroid/lipid-derived hormones diffuse through the plasma membrane of target cells. They enter the nucleus and attach to receptors within the nucleus and activate genes that result in the synthesis of new proteins.

Corticotropin releasing hormone

Stimulates the anterior pituitary to release ACTH.

Which two digestive system organs are important sources of hormones associated with digestion?

Stomach and small intestines.

T3 is a conversion of

T4 at target tissues.

Adrenocorticotropic hormone

Targets the adrenal gland to release glucocorticoids and mineralocorticoids.

Amine/Amino Acid-Derived Hormones

The amino acid-derived hormones are relatively small molecules that are derived from the amino acids tyrosine and tryptophan. If a hormone is amino acid-derived, its chemical name will end in -ine. Examples of amino acid-derived hormones include epinephrine and norepinephrine, which are synthesized in the medulla of the adrenal glands, and thyroxine, which is produced by the thyroid gland. The pineal gland in the brain makes and secretes melatonin which regulates sleep cycles. Amino acid-derived hormones are water-soluble.

What are the two functional lobes of the pituitary gland?

The anterior pituitary, made from glandular tissue, and the posterior pituitary, composed of nervous tissue.

Pituitary gland

The endocrine system's most influential gland. It is the size of a pea and hangs by a stalk from the hypothalamus in the brain. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands. It is also protected by the sphenoid bone.

Adrenal medulla

The inner neural tissue region of the adrenal gland. It secretes epinephrine and norepinephrine.

Walking barefoot, you step on a piece of broken glass and immediately pull your foot back. Why is it important that the signal triggering this motion came from the nervous system and not from the endocrine system?

The nervous system is fast acting.

If the endocrine system is the second controlling system of the body, what is the primary?

The nervous system which is fast acting.

Adrenal cortex

The outer glandular region of the adrenal gland that has three layers. Mineralocorticoids are secreted by the outermost layer. Glucocorticoids are secreted by the middle layer. And sex hormones secreted by the innermost layer.

The pancreatic Islets

The pancreas is a mixed gland and has both endocrine and exocrine functions. The pancreatic islets produce the hormones insulin and glucagon. They are antagonists that maintain blood sugar homeostasis.

How are the thyroid and parathyroid glands linked anatomically?

The parathyroid glands are four tiny glands located behind the thyroid gland.

Where are the hormones oxytocin and antidiuretic hormone (ADH) stored?

The posterior pituitary gland stores oxytocin and ADH, which come from the hypothalamus. The axon terminals of neurons of the hypothalamic-hypophyseal tracts store and secrete ADH and oxytocin in the capillaries of the inferior hypophyseal artery (c).

Explain the three types of stimuli to release hormones

The stimuli that activate the endocrine organs fall into three major categories--hormonal, humoral, and neural. The most common stimulus is hormonal, in which endocrine organs are prodded into action by other hormones. Humoral stimuli are the changing blood levels of certain ions and nutrients that can also activate endocrine organs. For example, decreasing blood calcium levels prompt the release of parathyroid hormone (PTH) by cells of the parathyroid glands. In isolated cases, nerve fibers stimulate hormone release, and the target cells are said to respond to neural stimuli. The classic example is sympathetic nervous system stimulation of the adrenal medulla to release norepinephrine and epinephrine during periods of stress.

Protein/Peptide Derived Hormones

The structure of peptide hormones is that of a polypeptide chain (chain of amino acids). The peptide hormones include molecules that are short polypeptide chains, such as ADH and oxytocin produced in the brain and released into the blood by the posterior pituitary gland. This class also includes small proteins, like growth hormones produced by the pituitary, and large glycoproteins such as FSH produced by the pituitary. Secreted peptides like insulin are stored within vesicles in the cells that synthesize them. They are then released in response to stimuli such as high blood glucose levels in the case of insulin. Amino acid-derived and polypeptide hormones are water-soluble. These hormones cannot pass through plasma membranes of cells; therefore, their receptors are found on the surface of the target cells.

What are the characteristics of all anterior pituitary hormones?

They are proteins (or peptides), act through second-messenger systems, and regulated by hormonal stimuli, mostly negative feedback.

How do thymosin and other thymus hormones help to protect the body?

Thymosin programs the T lymphocytes, which essentially directs the body's immune response.

What four pituitary hormones stimulate other endocrine glands (tropic hormones)?

Thyroid-stimulating hormone (thyrotropic hormone), adrenocorticotropic hormone, follicle-stimulating hormone, and luteinizing hormone.

Stimulates the thyroid gland to produce thyroxine.

Thyroid-stimulating hormone.

What are the parathyroid glands?

Tiny masses on the posterior of the thyroid that secrete parathyroid hormone (PTH).