Endocrine System

Glucagon acts as an antagonist (opposite) to insulin.

True

Describe all the steps of second messenger activation and include a description of what cAMP is and its role.

A. Hormone (first messenger) binds to a receptor protein on the plasma membrane B. An activated receptor sets off a series of reactions that activates an enzyme C. The enzyme catalyzes a reaction that produces a second-messenger molecule (such as cyclic AMP known as cAMP). cAMP is a second messenger, used for intracellular signal transduction, such as transferring into cells the effects of hormones like glucagon and adrenaline, which cannot pass through the plasma membrane. It is also involved in the activation of protein kinases. D. The second messenger oversees additional intracellular changes to promote a specific response in the target cells

Describe all the steps of direct gene activation including all steps that occur in the nucleus and in the cytoplasm.

A. Steroid hormone diffuses through the plasma membrane of target cells B. Once inside the cell, the hormone enters the nucleus C. Then, the hormone binds to specific proteins within the nucleus D. Hormone-receptor complex binds to specific sites on the cell's DNA E. Certain genes are activated to transcribe messenger RNA F. New proteins are synthesized

What are the three methods of stimulating endocrine glands? Include a brief description of each of these methods.

A. The stimuli that activate endocrine glands fall into three major categories: Hormonal, Humoral, and Neural. a. Hormonal Stimuli - The most common category of stimulus. Endocrine organs are activated by other hormones. Example: Hormones of the hypothalamus stimulate the anterior pituitary to secrete its hormones b. Humoral stimuli - Changing blood levels of certain ions and nutrients stimulate hormone release. Humoral indicates various body fluids such as blood and bile. Examples: 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 levels c. Neural stimuli - Nerve fibers stimulate hormone release. Most are under the control of the sympathetic nervous system. Example: sympathetic stimulation of the adrenal medulla to release epinephrine and norepinephrine

Which adrenal cortex hormone helps regulate water and electrolyte balance in body fluids?

Aldosterone

Explain the composition of the two major chemical classifications of hormones

Amino acid-based molecules(water-soluble) include proteins, peptides, and amines. The steroid hormones (lipid-soluble) include the sex hormones made by the gonads and the hormones produced by the adrenal cortex.

What is second messenger activation? Why is it called "second messenger" activation? What does it do?

Because most hormones are large molecules they can't directly pass through a cell membrane. Thus to "transmit" a signal, a hormone will bind to a receptor on the cell's membrane which will then activate "second messengers" within a cell, the second messengers are the ones who trigger molecular interactions that lead to altered cellular activity. cAMP (cyclic adenosine monophosphate) is created from ATP which is released when a protein attaches to a receptor. From there, cAMP will attach to protein kinase which will then change shape, and the newly activated protein will go on to "phosphorylate" (Add a phosphate group) other proteins. Thus this signaling pathway is called a phosphorylation cascade

Which of these hormones regulate calcium levels in the body?

Calcitonin and parathyroid hormone (PTH)

The two hormones released by the thyroid gland are ________.

calcitonin and thyroid hormone

Explain the effects of the catecholamines on the body during the fight-or-flight response, and how these effects help us deal with short-term stress

Catecholamines include neurotransmitters such as dopamine, epinephrine (adrenaline) and norepinephrine (noradrenaline), which are released during the body's stress response. The immediate effects of catecholamines include: Constricting the blood vessels in the skin, Increasing glucose in your bloodstream Increasing your cardiac output, Making you feel excited, Opening up your lungs, Retaining sodium, Sending more blood flow to your skeletal muscles, and Slowing down the intestines.

The endocrine system is heavily involved in homeostatic control of the levels of calcium and glucose in the blood. Which endocrine glands are involved in both of these processes and which hormones are involved? Describe, in detail how each of these works. Be sure to describe the endocrine glands involved, the hormones released and what triggers the release of the hormones. Also be sure you mention what is targeted by the hormones and how that target reacts to restore balance.

Control of Calcium: The parathyroid gland releases calcitonin and parathyroid hormone in response to changes in the level of calcium in the blood. Calcitonin regulates calcium levels by decreasing it acting in direct opposition to PTH which increases blood calcium levels. Calcitonin lowers calcium levels by blocking the activity of osteoclasts which are cells that break down bone and release it into the bloodstream thus by stopping osteoclasts calcitonin reduces the amount of blood entering the bloodstream. The parathyroid hormone stimulates the release of small amounts of calcium from the bones into the bloodstream, Control of Glucose: The pancreas gland controls blood sugar levels because it releases the hormones insulin and glucagon in response to changing blood sugar levels. Blood sugar rises after the digestion of food. In response, pancreas cells are stimulated to secrete insulin, which enables sugar uptake by cells and the storage of sugar in the liver and muscles while glucagon stimulates the release of sugar by the liver.

Antidiuretic hormone promotes both sodium and water retention.

False

Blood calcium levels are controlled by a positive feedback mechanism.

False

The posterior pituitary makes and secretes oxytocin and antidiuretic hormone (ADH).

False

Hormones of the hypothalamus stimulate the anterior pituitary gland to secrete its hormones. How would you classify this type of endocrine gland stimulation?

Hormonal

Describe the three types of stimuli that activate the endocrine organs

Hormonal stimuli are the most common, where endocrine glands are activated by other hormones called tropic hormones. With humoral stimuli, the changing blood levels of certain ions and nutrients stimulate hormone release. Lastly is neural stimuli, where nerve fibers stimulate hormone release.

What are hormones? What is their role and what kind of biological molecule are they?

Hormones are chemical substances that act like messenger molecules in the body. After being made in one part of the body, they travel to other parts of the body where they help control how cells and organs do their work. Hormones are classified chemically as : amino acid-based, which includes: proteins, peptides, steroids, and prostaglandins.

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

catalyze a reaction that produces cyclic AMP (cAMP)

Alcohol inhibits the secretion of antidiuretic hormone (ADH). What impact will this have on the body?

Increased thirst and dehydration

What stimulates the release of calcitonin?

Increasing level of blood calcium ions

The gland that produces melatonin is indicated by ________.

Label A

The pineal gland is indicated by ________.

Label A

The gland that produces oxytocin and antidiuretic hormone is indicated by ________.

Label B

The gland that is primarily responsible for regulating metabolism is indicated by ________.

Label D

The glands that produce a hormone that is the most important regulator of calcium ion homeostasis of the blood are indicated by ________.

Label E

The glands that produce catecholamines are indicated by ________.

Label G

The gland that produces insulin and glucagon is indicated by ________.

Label H

The gland that produces testosterone is indicated by ________.

Label J

Where does the body store excess glucose as glycogen in response to the presence of insulin?

Liver

Which hormones are made by the hypothalamus yet stored and released by the posterior pituitary?

Oxytocin; antidiuretic hormone (ADH)

Discuss the role of hormones in maintaining blood calcium levels

PTH is the most important regulator of blood calcium levels, it is secreted by a humoral stimulus in response to low blood calcium levels. It activates osteoclasts to destroy bone matrix and release the calcium into the blood, raising levels, and it has the intestine and kidneys to absorb calcium. PTH world opposite to calcitonin, whose job is to lower blood calcium levels.

Which two hormones act together to bring about menstruation in females?

Progesterone and estrogen

What is direct gene activation? What does it do?

Steroid hormones pass through the plasma membrane (they're lipid-soluble) and attach to receptor molecules that are inside the cell. This combination is now an activated "hormone-receptor complex" which binds to the chromatin (on another receptor site). When a hormone-receptor complex binds to specific receptors DNA transcription occurs. Those genes to which the complex binds will then be transcribed and thus the hormone-receptor complex acts as a transcription factor (proteins involved in the process of converting, or transcribing, DNA into RNA). Certain genes are activated to transcribe messenger RNA and new proteins are synthesized

What is the primary effect of prolactin?

Stimulate and maintain milk production after childbirth

Which of the following is not an effect of testosterone on males?

Stimulation of the posterior pituitary

What is the role of the endocrine system? How does this differ from the role of the nervous system?

The endocrine system is the second controlling system of the body that uses chemical messengers (hormones) that are released into the bloodstream to control several major processes. It differs from the nervous system because the nervous system uses quick electrical signals transmitted through neurons that to deliver messages while the endocrine system delivers messages slower (by comparison) through the use of hormones.

What is the primary function of thymosin?

Thymosin appears to be essential for the normal development of T lymphocytes.

Growth hormone promotes the growth of skeletal muscles and long bones of the body.

True

Hormones only affect certain tissue cells or organs known as target cells or target organs.

True

Oxytocin is released in significant amounts only during childbirth and nursing.

True

Parathyroid hormone (PTH) is the most important regulator of calcium ion homeostasis of the blood.

True

The primary method of maintaining blood levels of nearly all hormones is through negative feedback mechanisms.

True

Diabetes is a disorder that results in glucose levels in the blood being too high. There are two types, Type I and Type II diabetes. They both have the same result, high blood sugar, but are caused by different mechanisms. Please describe each type in detail, outlining how each of them results in increased levels of glucose in the blood. Finally, research why high glucose levels are bad and what the short-term and long-term effects are of elevated blood sugar levels

Type I Diabetes: In this type of diabetes the pancreas does not make enough insulin which results in high blood sugar because without insulin the glucose can't be absorbed into cells. This type of diabetes is a medical condition. Type II Diabetes: This type of diabetes is self-induced and is caused by having high levels of blood sugar resulting in the pancreas not being able to create enough insulin for it to be absorbed so it remains in the blood. Short-term Effect of High Blood Sugar: Short-term complications of high blood sugar are hypoglycemia and hyperglycemia. Hypoglycemia is when the blood sugar level is too low and can result in irregular heart rhythm, fatigue, pale skin, shakiness, and anxiety. While hyperglycemia results in frequent urination, increased thirst, blurred vision, fatigue, and headaches. Long-term Effects of High Blood Sugar: long term complications of diabetes are kidney disease, eye damage, heart disease, and nerve damage.

Adrenocorticotropic hormone (ACTH) promotes the release of ________,

cortisone and cortisol

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

adrenocorticotropic hormone (ACTH)

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

androgens

Which hormone causes the kidneys to reabsorb more water from forming urine and as a result, increases blood volume?

antidiuretic hormone (ADH)

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

epinephrine

Which of these hormones is released by the adrenal medulla?

epinephrine (adrenaline)

Which hormone is produced by the kidneys to stimulate the production of red blood cells by the bone marrow?

erythropoietin

What two groups of steroid hormones are made by female ovaries?

estrogens and progesterone

Which hormone, produced by the placenta, stimulates the ovaries to continue producing estrogen and progesterone so that the lining of the uterine is not sloughed off in menses?

human chorionic gonadotropin (hCG) Submit

Parathyroid hormone (PTH) is secreted by the parathyroid glands in response to low blood concentration of calcium ions. This mechanism operates by a ________.

humoral stimulus

The short-term stress response of epinephrine, such as running from a fire, includes all of the following except ________.

increased digestive activity

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; glucagon

The pineal gland produces ________.

melatonin

Which hormone appears to play an important role in establishing the body's sleep-wake cycle?

melatonin

Rising levels of parathyroid hormone (PTH) will inhibit its further hormone release. This type of control mechanism is best described as ________.

negative feedback mechanism

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

parafollicular

Which endocrine gland is known as the "master endocrine gland" for its removal or destruction would have a dramatic effect on the body?

pituitary gland

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

prolactin (PRL) and oxytocin

Which of the following is a function of the mineralocorticoids, such as aldosterone?

regulate salt content of the blood

The hormone produced by male testes, which is necessary for sperm production is ________.

testosterone

In the second-messenger system, what serves as the first messenger?

the hormone

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

the second-messenger system

What gland is the target organ of thyrotropic hormone (TH), also known as thyroid-stimulating hormone (TSH)?

thyroid gland

The body's major metabolic hormone, which is actually two iodine-containing hormones, is called ________.

thyroid hormone