Endocrine System

Which endocrine gland receives hormonal signals secreted by the hypothalamus and transported via the hypophyseal portal vein?

Adenohypophysis-The hypophyseal vein connects capillaries of the hypothalamus to the capillaries of the adenohypohysis (anterior pituitary).

The outer layer of the adrenal gland.

Adren-al Cortex-"Cortex" refers to outer covering.

Which of the following would bind to an intracellular receptor?

Aldosterone is a lipid soluble hormone that diffuses across a cell membrane and binds to an intracellular receptor.

In type I diabetes, the pancreatic beta cells are destroyed by an immune reaction. This would lead to:

An inability to secrete insulin. Pancreatic beta cells both sense insulin levels and secrete insulin.

Which of the following hormone is antagonistic (has the opposite effect on the body) to parathyroid hormone?

Calcitonin-Though now generally accepted to only be important in children, it works opposite to parathyroid hormone.

Which of the following is a chemical classification of a hormone?

Carbohydrate derived

Adrenal Gland Medulla

Catecholamines (epinephrine and norepinephrine) Various tissues Stimulate the fight-or-flight response.

The primary cells of the parathyroid glands are called:

Chief cells-These cells secrete parathyroid hormone.

Which of the following is a function of the endocrine system?

Contribute to homeostatic feedback loops. Alter the metabolic activities of many different target tissues and organs. Release chemicals into the bloodstream for distribution throughout the body.

If a person had not eaten a meal recently, which of the following hormone combinations could help raise blood glucose levels?

Cortisol and glucagon Each of these work to increase plasma glucose levels.

Which of the following organ systems do/does contain an organ that secretes hormones?

Digestive Cardiovascular Renal

Which of the following components of a feedback loop is LEAST likely to be part of the endocrine system?

Effectors are generally organs and tissues that respond to the hormone. These organs and tissues tend to be structures associated with other organ systems.

Which of the following hormones is properly matched with its precursor?

Epinephrine - Tyrosine Cortisol - Cholesterol

The catecholamines are one class of tyrosine amine hormones and include:

Epinephrine and norepinephrine are collectively known as catecholamines.

Which of the following is an amino acid derived hormone?

Epinephrine is derived from the amino acid tyrosine.

75-80% of adrenal medulla hormone secretions is:

Epinephrine is the majority of secretion from the adrenal medulla.

Ovaries

Estrogen Various tissues Development of secondary sex characteristics Progesterone Uterus Regulates thickening of inner layer.

What would be the stimulus and effect if both alpha and beta cells were secreting their hormone?

F or PP cells can stimulate both insulin and glucagon release after a high protein meal or fasting. In the case of protein, glucagon will stimulate the conversion of excess protein into glucose and insulin will lower the resulting increase in blood glucose. In the case of fasting, both are needed to ensure glucose is made available, despite the lack of food intake. Just as with a high protein diet, both hormones contribute to sustaining the cells.

The endocrine function of the pancreas mainly regulates:

Glucose metabolism.-Pancreatic hormones regulate plasma glucose levels by adjusting glucose usage and storage.

Anterior Pituitary

Growth Hormone All Tissues Growth Thyroid-stimulating hormone (TSH) Thyroid Stimulates release of hormones from the thyroid. Adrenocorticotropic hormone (ACTH) Adrenal Cortex Stimulates release of hormones from the adrenal cortex. Gonadotropins (Follicle stimulating hormone and Luteinizing Hormone) Gonads - Testes and Ovaries Stimulate gamete and sex hormone production. Prolactin

If you had to summarize the function of the endocrine system in one word, what would it be?

Homeostasis-The endocrine system's main function is to maintain homeostasis. However, growth, development and communication are also important endocrine system functions.

Luteinizing Hormone:

Hormonal regulation -Anterior pituitary hormones are controlled through hormonal regulation from the hypothalamus. The hypothalamus might respond to substances in the blood in order to direct the anterior pituitary hormones

Cortisol

Hormonal regulation This hormone is under control of adrenocorticotropic hormone released from the anterior pituitary.

The structures that carry messages through the bloodstream are called:

Hormones are the molecules that travel through the bloodstream, carrying their message with them.

Calcitonin

Humoral regulation-Calcitonin is released when plasma calcium levels decrease below normal.

Parathyroid Hormone:

Humoral regulation-Parathyroid hormone levels are determined by the amount of calcium in blood plasma.

Insulin

Humoral regulation-Plasma glucose levels regulate insulin release.

What is the major function of the thyroid hormones?

Increase metabolic rate. The thyroid hormones regulate metabolism.

Which hormone is secreted by multiple endocrine glands?

Inhibin is produced by both the testes and the ovaries.

Pancreas

Insulin Liver, Muscle, Adipose Tissue Lowers blood glucose levels. Glucagon Liver Raises blood glucose levels.

When blood glucose levels fall below their set point:

Insulin secretion decreases and glucagon secretion increases. Less insulin means less signal to remove glucose from the blood. Glucagon stimulates glucose release from storage sites (the liver in particular) back into blood.

Oxytocin is unique because it?

Is regulated by a positive feedback cycle.

Which of the following accurately describes the function of the hypothalamus?

It is a link between the nervous system and the endocrine system. The hypothalamus has both nervous system and endocrine functions and is a link between them.

Which of the following correctly identifies the location of the pineal gland?

It is located in the diencephalon of the brain. The diencephalon includes the thalamus and hypothalamus and the pineal gland is located on the posterior side of the thalamus.

What is the best description of the hormone inhibin?

It is produced by the gonads and inhibits FSH release. Inhibin is produced by the ovaries and testes, which are the gonads and inhibits FSH release.

Which of the following correctly describes the target cells for a hormone?

It possesses receptors for that specific hormone. Target cells are those cells that have receptors for the hormones.

Release of melatonin by the pineal gland is regulated by:

Light entering the eyes. The more light that enters the eyes, the less melatonin is released.

In your own words explain how positive and negative feedback loops contribute to function of the body.

Negative feedback will work to minimize the change from the set point of the variable being controlled. Signals will stop the change when the ideal state is reached. Positive feedback continues to move the body in a specific direction away from a set point. It will increase the impact of the stimuli instead of decreasing it.

Epinephrine

Neural regulation-Neurons of the sympathetic nervous system directly stimulate the release of epinephrine from the adrenal medulla.

Oxytocin

Neural regulation-Oxytocin is released based on neural activity in the hypothalamus.

Which endocrine organ is located on either side of the uterus

Ovaries There is one ovary on each side of the uterus.

Which hormone is involved in a positive feedback loop?

Oxytocin is involved in a positive feedback loop during childbirth.

Which of the following is primary endocrine gland?

Pancreas Adrenal Thyroid

Which structure is found in the thyroid gland?

Parafollicular cells Right and left lobes Follicles

Which hormone is released from the parathyroid gland?

Parathyroid-In this case, the hormone is named for the gland that releases it.

Peptide hormones.

Peptide hormones are a diverse group of hormones of varying lengths. They include molecules that are only a few amino acids, such as antidiuretic hormone and oxytocin (each with 9 amino acids), proteins, such as growth hormone (191 amino acids) and insulin (51 amino acids), and glycoproteins, such as follicle-stimulating hormone (92 amino acids with glycosylation). Most are water soluble and are easily transported in blood plasma and have a half life of minutes. They bind to extracellular receptors.

Some glands are stimulated by neurons rather than hormones (tropic) or receptors monitoring an internal stimulus that changes (humoral). Which of the following gland's secretion is regulated by neural stimuli?

Posterior pituitary Adrenal medulla Pineal gland

Skin

Precursor is produced in the epidermis of the skin.Cholecalciferol

Adipose Tissue

Produced by adipocytes of white adipose tissue.Leptin

Kidneys

Produced by specialized cells of the juxtaglomerular apparatus.Renin Produced by the proximal tubule of the nephron.Calcitriol (Vitamin D) Produced by interstitial fibroblasts in the kidney.Erythropoietin

Gastrointestinal Tract

Produced by the G-cells of the stomach and also by cells of the small intestine and pancreas.Gastrin Produced by the S-cells of duodenum of the small intestine.Secretin Produced by the I-cells of the small intestine.Cholecystokinin

Heart

Produced by the muscles cells of the atria.Atrial Natriuretic Peptide (ANP)

Which of the following variables is LEAST likely to be directly measured by a sensor?

Rate of growth.

The endocrine function of the gonads is to regulate:

Secondary sex characteristics. Without the sex hormones, sexual development does not occur.

The adrenal cortex releases ________________ hormones.

Steroid-These hormones are derived from cholesterol.

Steroids are derived from the precursor:

Steroids are lipid hormones derived from cholesterol.

Which of the following is a way that parathyroid hormone increases blood calcium levels?

Stimulates the reabsorption of calcium from the kidneys. Stimulates the absorption of calcium from the intestines. Decreasing the amount of calcium lost in urine.

Which hormone(s) secreted by the anterior pituitary control(s) the function of other endocrine gland(s)?

TSH ACTH FSH

A cell that has a receptor for a specific hormone is called a:

Target cell Cells that have the receptor for a specific hormone is the target cell for that hormone.

Which of the following endocrine organs is a paired organ?

Testes Ovaries

Which of the following glands is a source of a steroid hormone?

Testes Ovaries Adrenal gland

The gonads include:

Testes and ovaries. The gonads produce gametes.

Testes

Testosterone Various tissues Development of secondary sex characteristics.

Negative feedback means:

That as a variable changes from its set point, the loop will take action to oppose the change.

Which if the following statements is true regarding the pancreas?

The endocrine cells are in clusters called pancreatic islets. Only a small fraction of the cells in the pancreas have endocrine function and they are separated into small groups in the pancreatic islets.

What benefit does signaling via the endocrine system have in comparison to signaling by the nervous system?

The endocrine system is better at longer-term signaling. The neurotransmitters released by the nervous system are very short-lived and would require repeated release to maintain a sustained response. Some hormones can elicit an extended response with little hormone released.

In the case where a hormone controls many variables, what does the feedback loop often measure?

The level of the hormone. This system results in stable hormone levels.

Neural Stimuli

The nervous system can also directly stimulate endocrine glands to release hormones through a mechanism known as neural stimuli.

Ovaries

The ovaries secrete the hormones estrogen and progesterone into the bloodstream.

nine primary endocrine glands

The pituitary gland is located inferior to the hypothalamus of the brain. The pineal gland is located between the two cerebral hemispheres of the brain. The thyroid gland lays over the trachea, and the parathyroid glands are located on the posterior side of the thyroid gland. The thymus is located near the heart. The adrenal glands sit on top of the kidneys. The pancreas is located near the stomach and extends to the spleen. The testes are found only in males outside of the body cavity in the scrotum. The ovaries are found only in females on either side of the uterus. The next module will look more closely at the location and structure of the major glands.

What hormone(s) are produced by the posterior pituitary?

The posterior pituitary does not produce any hormones. It only stores hormones produced by the hypothalamus.

Humoral Stimuli

The term humoral is derived from the term humor, which refers to bodily fluids such as blood and other extracellular fluids. Humoral stimuli regulate the release of hormones in response to specific changes in extracellular fluids, such as the concentration of a particular ion or solute (such as glucose) in the blood. Antidiuretic hormone levels are determined based on the overall solute concentration (osmolarity) in the blood.

Which endocrine organ is located outside of the body cavities?

The testes hang, separated from the body cavities, in the scrotum.

Thyroid Gland:

The thyroid gland secretes thyroid hormone into the bloodstream.

The response of a cell responding to a hormone is mainly dependent on?

The type(s) of receptor(s) it has. It is the receptor that determines the response of the cell.

Which of the following correctly describes an endocrine gland?

Their hormones travel to distant cells through the blood.

Contains Chromaffin cells.

These are the cells of the adrenal medulla.

Which of the following statements is true about endocrine glands?

They always secrete hormones. They are not located in the extremities. They secrete into the bloodstream.

Lipid derived hormones (steroids)

They are derived from the lipid cholesterol. They are insoluble in water, so to circulate through the blood they bind to transport proteins in the plasma. Since they are bound to carrier proteins, steroid hormones typically remain in circulation longer than other classes of hormones, with a half-life of 60 to 90 minutes. These hormones typically bind to intracellular receptors.

Peptide hormones must bind to a plasma membrane hormone receptor because:

They are polar meaning they will not be able to pass through the nonpolar portion of the plasma membrane.

Target cell receptors for melatonin are found in the hypothalamus and pituitary. What is the functional significance of this anatomical feature?

Through the major homeostasis centers and "master gland" with tropic hormones, melatonin can influence many different targets in the body. Normally this sets up a circadian rhythm of metabolism, but it also accounts for the wide range of effects associated with jet lag or shift work.

Thymus

Thymosin T-cells Maturation of T-cells.

Which of the following is a primary endocrine organ?

Thyroid Testes Adrenal Pituitary gland

Hormonal Stimuli

With hormonal stimuli (sometimes called tropic hormone stimuli), a hormone is produced and released by an endocrine gland in response to another hormone (known as "tropic hormones").

How many adrenal glands does each person have?

You have two kidneys with an adrenal gland sitting atop each.

The two glandular parts of the adrenal gland are the

cortex and medulla. The outer cortex produces steroid-derived hormones and the inner cortex produces the catecholamines epinephrine and norepinephrine.

The pineal gland

is located between the cerebral hemispheres of the brain. It is attached to the roof of the third ventricle in the diencephalon. The pineal gland consists of secretory cells, called pinealocytes, that secrete the hormone melatonin. Melatonin is derived from the neurostransmitter serotonin and is regulated in response to the light and dark of the environment (the diurnal cycle). Photons, packets of light, are detected by the retinas of the eyes, which initiate a nerve impulse that is conducted to the pineal gland

thymus

is located medially in the upper thorax and functions in immune cell development.

The adrenal cortex

is made up of layers of epithelial cells and associated capillary networks. These layers form three distinct regions that secrete different steroid hormones: the outer zona glomerulosa produces mineralocorticoids (influence salt and water balance), the middle zona fasciculata produces glucocorticoids (impact metabolism and inflammation), and the inner zona reticularis produces androgens (regulate nutrient processing and sexual characteristics).

The endocrine system

is made up of the hormone-secreting glands, although there are other organs and tissue that also secrete hormones and are considered to have have secondary endocrine function (such as the stomach and adipose tissue).

Each hormone released by the endocrine system

is part of a homeostatic feedback loop. All hormones act as a means of communication in feedback loops.

Oxytocin

is secreted by the hypothalamus and stored in the posterior pituitary gland. Its target cells are located in the uterus and mammary glands. Oxytocin secretion is stimulated by the head of the baby putting pressure on the cervix of the uterus during labor.

Blood glucose

levels are primarily regulated by the pancreatic hormones insulin and glucagon. It is important that blood glucose levels stay within an adequate range because it is the only fuel source that our neurons use on a regular basis. It is also the preferred energy source of most other body cells. Blood glucose levels that are too low cause confusion and lethargy, while levels that are too high cause short-term problems like osmotic imbalances and long-term problems such as blood vessel damage.

Contains the middle zona fasciculata.

There adrenal cortex has 3 zones and this is the middle one.

Which hormone counteracts insulin?

Glucagon is released by pancreatic alpha cells and has effects that oppose those of insulin.

Aldosterone

Humoral regulation Plasma potassium levels are the main determinant of aldosterone levels.

Which of the following correctly describes the structure of the posterior pituitary?

It is an extension of the brain. The neurohypophysis is an extension of the hypothalamus.

Pineal Gland

Melatonin Hypothalamus and Anterior Pituitary Regulate sleep cycles.

What hormone is produced by the pineal gland?

Melatonin is the hormone produced by the pineal gland.

Parathyroid Gland

Parathyroid hormone (PTH) Kidneys and Bones Raise blood calcium levels.

The parathyroid glands are located:

Posterior to the thyroid gland. They are located on the "back" of the thyroid gland.

The main role(s) of the endocrine system is/are to:

Provide a means of communication in feedback loops. Hormones are important molecules for transmitting messages.

Contains endocrine cells.

The cortex releases its various hormones from endocrine cells.

Which of the following is a true statement concerning a secondary messenger?

The hormone that triggers the secondary messenger is called the first messenger. Amino acid and peptide hormones use them to affect change inside the cell. Common secondary messengers are G-protein coupled receptors.

What are all anterior pituitary hormones controlled by?

The hypothalamus controls all anterior pituitary hormones through hormonal regulation.

The four parathyroid glands

are each the size of a large grain of rice and are usually located on the posterior surface of the thyroid gland. The exact location and number of parathyroid glands can vary from person to person. The parathyroid glands are named for their proximity to the thyroid gland (para- means next to) and may be hard to distinguish from the thyroid gland. The parathyroid glands are composed mainly of chief cells, which secrete parathyroid hormone (PTH).

The pineal gland is located

in the brain-The pineal gland and the pituitary gland are primary endocrine organs located in the brain.

The parathyroid glands are located _________.

in the neck-The parathyroid glands are attached to the posterior side of the thyroid glands, placing them in the neck.

Insulin

is a hormone that is under humoral control and is regulated by a negative feedback loop. Below is a figure depicting the negative feedback loop of insulin regulating glucose levels.

This capillary network

is a part of the hypophyseal portal system that carries signaling molecules from the hypothalamus directly to the anterior pituitary. Anterior pituitary hormones then enter the capillaries and travel to the heart and through the systemic system in the same way other hormones do. The anterior pituitary gland is sometimes called the master gland. It gets this name because of the large number of tropic hormones that it secretes.

A receptor

is a protein (cell membrane or intracellular) that binds specifically to a particular hormone and initiates a cellular response. Receptors for a specific hormone may be found in or on many different target cells, or may be limited to a small number of specialized cells.

The pancreas

is an elongated organ whose endocrine function plays a central role in energy metabolism, storage, and utilization of glucose (carbohydrate) It is located slightly dorsal to the stomach and between the stomach and the small intestine. It can be divided into different regions based on the overall shape of the pancreas and by the functions of its cells.

The level of a hormone found in the blood stream depends on:

Both the rate it is produced and the rate it is broken down. Each of these contributes to the level of hormone in the bloodstream.

The pineal gland is located in the:

Brain-It is located between the two cerebral hemispheres.

Posterior Pituitary

Antidiuretic hormone (ADH; also called vasopressin) Kidneys, Blood Vessels Stimulates water reabsorption and vasoconstriction. Oxytocin Uterus Promotes contractions during labor.

Which of the following is an example of a peptide hormone produced by the hypothalamus and stored in the posterior pituitary?

Antidiuretic hormone is short polypeptide chain-based hormone.

Which of the following accurately describes hormones?

Are chemical messengers. Hormones are chemical messengers.

Hormones released from the posterior pituitary are made in the:

Hypothalamus-These hormones are made in the neurosecretory cells in the hypothalamus and transported along the length of the cell for storage and release.

The region of the nervous system that controls many endocrine glands is the:

Hypothalamus-This central nervous system structure controls the pituitary gland.

Adrenal Gland Cortex

Mineralocorticoids (aldosterone) Kidneys Water Balance. Glucocorticoids (cortisol) Liver Immune function Macromolecule metabolism Gonadocorticoids Gonads Primary and secondary sex characteristics.

Which of the following glands is matched with its correct hormone?

Pineal Gland - Melatonin Pancreas - Insulin Ovaries - Progesterone Anterior Pituitary - Growth Hormone

What are the levels of parathyroid hormone most directly regulated by?

Plasma calcium levels-This is a "standard" negative feedback loop, where the variable of interest controls the rest of the loop.

What feature of the vascular network involving the hypothalamus and pituitary allows for fast communication between the hypothalamus and the anterior pituitary?

Portal system-This system allows hormones to enter capillaries in the hypothalamus and exit another capillary bed in the anterior pituitary.

The endocrine system

is composed of the glandular organs that secrete hormones as their main functions. The term endocrine means that the the cells secrete their signaling molecules into the bloodstream to act at a distant site

Contains the outer zona glomerulosa.

The adrenal cortex has 3 zones and this is the outermost one.

Adrenal Cortex:

The adrenal cortex secretes multiple hormones, including cortisol and aldosterone, into the bloodstream.

Contains neurosecretory cells.

The adrenal medulla is part of the sympathetic nervous system.

Part of the sympathetic nervous system.

The adrenal medulla releases hormones in response to sympathetic nervous system activity.

Adrenal Medulla:

The adrenal medulla secretes the hormone epinephrine into the bloodstream.

Amino acid derived hormones.

The amino acid tyrosine is the precursor for two groups of hormones: the thyroid hormones, produced in the thyroid gland; and the catecholamines (epinephrine and norepinephrine), produced in the adrenal medulla. The amino acid tryptophan is the precursor for the hormone melatonin, secreted by the pineal gland. Some of these hormones have a circulating half-life of a few days (thyroid hormones) while some are rapidly degraded (catecholamines). Thyroid hormone binds to an intracellular receptor while the the others bind to extracellular receptors.

Anterior Pituitary:

The anterior pituitary secretes several hormones into the bloodstream, including thyroid-stimulating hormone and growth hormone.

What would happen to a body cell that doesn't have a receptor for a hormone that is released and circulating in the blood?

The cell would not respond to the hormone. A cell will only respond if it has a receptor for a specific hormone, regardless of the amount circulating and coming into contact with that cell.

What would happen to a body cell if a hormone receptor was completely blocked by another chemical, such as a drug?

The cell would not respond to the hormone. If the receptors were blocked completely, it is as if the cell did not have any receptors for that hormone.

Thyroid Gland

Thyroid Hormones (thyroxine and triiodothyronine) All Tissues Stimulate metabolism. Calcitonin Kidneys and Bones Reduces blood calcium levels.

Which of the following structure of the thyroid is properly matched with its description?

Thyroid follicles - Contain a fluid called colloid. Isthmus - Connects the two lobes of the thymus. Parafollicular cells - Located in between the thyroid follicles.

T3 and T4 are types of:

Thyroid hormones.They represent triiodothyronine and thyroxine.

A hormone that controls the secretion of another hormone is called:

Tropic indicates that it is a hormone that acts on another gland.

Hormones that control the release of another hormone are called?

Tropic means to turn toward and regulate other hormones.

endocrine system

is involved with growth, development and adaptation, and control of various plasma ions (calcium, potassium and sodium in particular), which can be regulated on a slower time scale than functions such as thoughts or muscle contractions.

The pituitary gland or hypophysis

is a pea-sized gland located at the base of the brain attached to the hypothalamus via a stalk called the infundibulum. It is surrounded by bone and is found in a depression of the sphenoid bone. The pituitary has two distinct regions: the anterior pituitary and the posterior pituitary.

The hypothalamus

is a region of the brain that is located inferior to the thalamus. It receives information from internal organs, the blood, and other regions of the brain and acts as the control center for homeostatic feedback loops involving the pituitary gland

A second-messenger system

is an intracellular signaling pathway that triggers specific effects associated with the hormone. It is called a second-messenger system because the hormone that initiates the signaling pathway is considered the first messenger. Common second messenger systems include G-protein coupled receptors and tyrosine kinase receptors.

Testosterone

is associated with male sexual characteristics, while progesterone and estrogen are associated with female reproductive function; androstenedione is an intermediate molecule in the synthetic pathways of these and many of the steroid hormones

The thyroid gland

resembles a butterfly laying over the trachea in the neck region. The "wings" of the thyroid gland are the right and left lobes. The lobes are connected to one another by a thinner region called the isthmus. The thyroid gland is made up of many spherical thyroid follicles, which are lined with simple cuboidal epithelium.