endocrine system

Four-year-old Tim is extremely small for his age, and he shows signs of mental retardation. His hair is thinning and his skin is dry. His parents have read about cretinism and pituitary dwarfism as possible diagnoses for their son and have taken him to the pediatrician for tests to be run. Which diagnosis do you think is correct? Explain why.

The likely diagnosis is cretinism. Hyposecretion of the thyroid hormone in early childhood leads to cretinism. Cretinism results in dwarfism and mental retardation. Cretinism also causes hair to be scanty and the dry skin. It is unlikely Tim suffers from pituitary dwarfism. Pituitary dwarfism results from hyposecretion of growth hormone in children but does not cause the other symptoms listed.

Describe the three types of stimuli that activates the endocrine organs

The most common stimulus is hormonal. In hormonal stimulus, endocrine organs are prodded into action by other hormones, known as tropic hormones. Another type of stimulus is humoral, in which changing blood levels of certain ions and nutrients stimulate hormone release. The third type of stimulus is neural, in which nerve fibers stimulate hormone release.

Polyphagia, polydipsia, and polyuria are the three cardinal signs of a disease known as

diabetes mellitus

Which hormone works against glucagon?

insulin

Sex hormones produced by the ovaries and testes:

promote the formation of sex cells

The body's major metabolic hormone is called ________.

thyroid hormones

Alcohol inhibits the secretion of ________.

ADH

Bronze skin color, hypoglycemia, and a reduced ability to cope with stress (burnout) are signs and symptoms of ________.

Addison's disease

Catecholamines are released by the ________.

adrenal medulla

Which of these anterior pituitary hormones regulates the activity of the cortex region of the adrenal gland?

adrenocorticotropic hormone (ACTH)

Male sex hormones produced by the adrenal cortex are called ________.

androgens

Releasing and inhibiting hormones produced by the hypothalamus influence the activities of the ________.

anterior pituitary gland

Alcohol suppresses the production of this hormone, ________, which normally promotes water retention and prevents dehydration.

antidiuretic hormone (ADH)

Which hormone is alternately known as vasopressin due to its effect on blood vessel diameter and blood pressure?

antidiuretic hormone (ADH)

Which one of the following is NOT a hormone produced by the anterior pituitary?

antidiuretic hormone (ADH)

hormone produced by the heart, known as ________, prevents the release of aldosterone in order to reduce blood volume and blood pressure.

atrial natriuretic peptide (ANP)

Insulin is produced by cells of the pancreatic islets called ________.

beta cells

Which of these hormones regulate calcium levels in the body?

calcitonin and parathyroid hormone

The two hormones released by the thyroid gland are ________.

calcitonin and thyroid hormone

Being lipid soluble, steroids can do all the following EXCEPT ________.

catalyze cyclic AMP

Which one of the following is NOT typical of the changes that follow the binding of a hormone to its target cells?

cellular mutations occur

Six-year-old Timothy is small for his age and shows signs of mental retardation. What disorder do you suspect?

cretinism

Which system produces chemical messengers known as hormones?

endocrine system

The "fight-or-flight" response triggers the release of ________.

epinephrine

Which of these hormones is released by the adrenal medulla?

epinephrine

Which hormones regulate the female's menstrual cycle?

estrogens and progesterone

The hormone that stimulates follicle development by female ovaries and sperm development by male testes is ________.

follicle stimulating hormone (FSH)

Cortisone and cortisol are types of ________ produced by the middle cortical layer of the adrenal gland.

glucocorticoids

Daniella has been diagnosed with Addison's disease. Which of the following does NOT match her signs or symptoms?

high blood pressure and edema

The most common stimulus for prodding endocrine glands into action is

hormonal

Most endocrine organs are prodded into action by other hormones; this type of stimulus is called ________.

hormonal stimulus

Home pregnancy tests check for a hormone in the female's urine called _____

human chorionic gonadotropin (hCG)

Which hormone is produced by the placenta that stimulates the ovaries to continue producing estrogen and progesterone?

human chorionic gonadotropin (hCG)

When blood glucose levels are too high, the beta cells of the pancreas release ________ to decrease levels

insulin

Which of the following hormones decreases blood glucose levels?

insulin

Beta cells of the pancreatic islets produce a hormone known as ________ while the alpha cells produce a hormone known as ____

insulin and glucagon

Prostaglandins are ________.

lipid hormones manufactured in cell plasma membranes

hormone called ________ is believed to play an important role in establishing the body's day-night cycle.

melatonin

Which of the following hormones is NOT classified as a steroid hormone?

oxytocin

The hypothalamus makes two hormones, ________ and ________, that are stored by the posterior pituitary.

oxytocin and ADH

Calcitonin is made by the ________ cells of the thyroid gland.

parafollicular

Where is calcitonin made?

parafollicular cells of thyroid

Tetany resulting from uncontrolled muscle spasms may indicate a malfunction of the

parathyroid glands

Hyposecretion of growth hormone during childhood leads to ________.

pituitary dwarfism

The endocrine gland most closely associated with the hypothalamus is the

pituitary gland

Which two hormones play a role in promoting the milk reflex and in maintaining breast milk production in a mother's breasts?

prolactin and oxytocin

Rising blood levels of aldosterone cause the kidney tubules to ________.

reabsorb sodium

Most hormones are

released upon stimulation by other hormones

The enzyme produced by the kidneys when blood pressure drops, stimulating a release of aldosterone, is called ________.

renin

Water-soluble hormones, such as proteins and peptide hormones, activate target cells using

second messenger system

Mineralocorticoids regulate the concentration of ________ and ________ ions in our blood.

sodium and potassium

Testosterone can be categorized as a(n) ________ hormone.

steroid

Tropic hormones ________.

stimulate certain endocrine glands to secrete hormones.

Estrogens do all of the following EXCEPT:

stimulate growth of facial hair

The hormone produced by male testes which is responsible for sperm production is

testosterone

The hormone responsible for the maturation of white blood cells known as T lymphocytes is

thymosin

hormone called ________ plays an important role in incubating a special group of white blood cells.

thymosin

The target organ of thyrotropic hormone (TH), or thyroid-stimulating hormone (TSH), is the ________ gland.

thyroid

Which of these hormones prods the thyroid gland to release thyroxine?

thyroid stimulating hormone (TSH)

Jamie is dehydrated from playing a rough game of football on a hot summer afternoon. Explain why beer is not a good choice of beverage considering what you know about antidiuretic hormone.

Antidiuretic hormone prevents urine production and promotes water retention by the kidneys. However, alcoholic beverages inhibit ADH secretion and result in a large output of urine. Jamie is already dehydrated and alcohol will only further that situation

Hypersecretion of glucocorticoids, often caused by a tumor, results in ________.

Cushing's disease

Jenny's grandfather frequently urinates and is often thirsty. What other signs or symptoms would help you to determine if he has diabetes mellitus or diabetes insipidus? Explain.

Diabetes mellitus is characterized by polyuria (excess urination), polyphagia (excess hunger), and polydipsia (excess thirst). This form of diabetes results from the hyposecretion of insulin and causes glucose to be lost in the urine. By contrast, diabetes insipidus results from the hyposecretion of antidiuretic hormone. This condition is characterized only by polyuria and polydipsia. Polyphagia is not associated with this type of diabetes and glucose is not lost in the urine. In addition, blood tests could be performed to measure the levels of glucose and antidiuretic hormone in the bloodstream.

The element necessary in the diet for proper thyroid function is ________.

Iodine

Explain the pituitary-hypothalamus relationship.

Hormones from the anterior pituitary are released in response to releasing and inhibiting hormones produced by the hypothalamus. The hypothalamus releases these hormones into the blood of the portal circulation, which connects the blood supply of the hypothalamus with that of the anterior pituitary. Hormones from the posterior pituitary are made in the hypothalamus by hypothalamic neurons. Those hormones are then stored in the posterior pituitary until their release is necessary.

Discuss the role of hormones in maintaining blood calcium levels.

Parathyroid hormone, produced by the parathyroid glands, is the most important regulator of blood calcium levels. It is secreted in response to low blood calcium levels, a humoral stimulus. Parathyroid hormone activates osteoclasts to destroy bone matrix and release the calcium into the blood, raising blood calcium levels. Parathyroid hormone also targets the intestine and kidneys to absorb calcium. Parathyroid hormone works opposite to calcitonin whose job is to lower blood calcium levels through deposition to bones.

A weight lifter named Jake is shocked to learn that his body produces small amounts of estrogen in addition to testosterone. Explain to him where this female sex hormone is produced.

The adrenal cortex makes small amounts of both estrogen and testosterone in both males and females throughout life. Although the majority of the hormones produced in this region of the adrenal cortex are androgens, some estrogens are also formed.

Explain the two major chemical classifications of hormones.

The amino acid-based molecules include proteins, peptides, and amines. The steroid hormones include the sex hormones made by the gonads and the hormones produced by the adrenal cortex.