Practice Anatomy and Physiology Chapter 10

List the steps of Membrane-Bound Receptors Activating G Proteins to Increase the Synthesis of cAMP

1. After a water-soluble hormone binds to its receptor, the G protein is activated. 2. The activated alpha subunit, with GTP bound to it, binds to and activates an adenylate cyclase enzyme so that it converts ATP to cAMP. 3. The cAMP can actiavte protein kinase enzymes which phosphorylate specific enzymes activating them. The chemical reactions catalyzed by the activated enzymes produce the cell's repsonse. 4. Phosphodiesterase enzyms inactivate cAMP by converting cAMP to AMP.

List the steps of Membrane-Bound Receptors Activating G Proteins

1. Before the hormone binds to its receptor, the G protein consists of three subunits, with GDP attached to the alpha subunit, and freely floats in the plasma membrane. 2. After the hormone binds to its membrane-bound receptor, the receptor changes shape, and the G protein binds to it. GTP replaces GDP on the alpha subunit of the G protein. 3. The G protein separates from the receptor. The GTP-linked alpha subunit activates cellular responses, which vary among target cells. 4. When the hormone seperates from the receptor, additional G proteins are no longer activated. Inactivation of the alpha subunit occurs when phosphate (P1) is removed from eh GTP, leaving GDP bound to the alpha subunit.

List the steps of Regulation of Calcium Ion Blood Levels.

1. Blood Ca2+ is within its normal range. 2. Blood Ca2+ level increases outside the normal range 3. The parafollicular cells and the parathyroid gland cells detect elevated blood Ca2+. The parafollicular cells secrete clacitoin; the parathyroid gland cells decrease PTH secretion. 4. There is less bone reabsorption and less uptake of Ca2+ from both kidney and the inestine. 5. Blood Ca2+ level drops back to its normal range. 6. Homeostasis is restored. Observe the response to a drop in blood Ca2+ by following the red arrows.

Homeostasis Figure 10.23 Regulation of Blood Glucose Levels.

1. Blood glucose is within its normal range 2. Blood glucose level increases outside the normal range. 3. The pacnreatic islets secrete insulin in direct response to elevated blood glucose. 4. Most itssues take up glucose when insulin binds to its receptr on the tissues. 5. Blood glucose level drops back to its normal range. 6. Homeostasis is restored. Observe the response to a drop in blood glucose by following the red arrows.

What are the major effects of the hormones released from the adrenal medulla?

1. Increases in the breakdown of glycogen to glucose in the liver, the release of the glucose into the blood, and the release of fatty acids from adipose tissue. The glucose and fatty acids serve as energy sources to maintain the body's increased rate of metabolism. 2. Increased heart rate, which causes blood pressure to rise. 3. Stimulation of smooth muscle in the wall sof arteries supplying the internal organs and the skin, but not those supplying skeletal muscle. Blood flow to internal organs and skin decreases, as do the functions of the internal organs. Blood flow through skeletal muscles increases. 4. Increased blood pressure due to smooth muscle contraction in the walls of blood vessels in the internal organs and the skin. 5. Increased metaolic rate of several tissues, especially skeletal muscle, cardiac muscle, and nervous tissue.

List the steps of Nuclear Receptor Model.

1. Lipid-soluble hormones diffuse through the plasma membrane. 2. Lipid-soluble hormones either bind to cytoplasmic receptors and travel to the nucleus or bind to nuclear receptors. 3. The hormone-receptor complex binds to a hormone-response element on the DNA, acting as a transcription factor. 4. The binding of the hormone-receptor complex to DNA stimulates the synthesis of messenger RNA (mRNA), which codes for specific proteins. 5. The mRNA leaves the nucleus, passes into the cytoplasm of the cell, and binds to ribosomes, where it directs the synthesis of specific proteins. 6. The newly synthesized proteins produce the cell's response to the lipid-soluble hormones-for example, the section of a new protein.

List the steps of Hypothalamus and Posterior Pituitary.

1. Stimuli within the nervous system cause hypothalamic neurons to either increase or decrease their action potential frequency. 2. Action potentials are conducted by axons of the hypothalamic neurons through the hypothalamohypohpysial tract to the posterior pituitary. The axon endings of neurons store neurohormones in the posterior pituitary. 3. In the posterior pituitary gland action potentials cause the release of neurohormones (blue circles) from axon terminals into the circulatory system. 4. The neurohormones pass through the circulatory system and influence the activity of their target tissues.

List the steps of Hypothalamus and Anterior Pituitary.

1. Stimuli within the nervous system regulate the secretion of releasing hormones (green circles) and inhibiting hormones (red circles) from neurons of the hypothalamus. 2. Releasing hormones and inhibiting hormones pass through the hypothalamopophysial portal system to the anterior pituitary 3. Releasing hormones and inhibiting hormones (green and red circles) leave capillaries and stimulate or inhibit the release of hormones (yellow squares) form anterior pituitary cells. 4. In response to releasing hormones, anterior pituitary hormones (yellow squares) travel in the blood to their target tissues (green arrow), which in some cases, are other endocrine glands.

List the steps for regulation of thyroid hormone (T3 and T4) Secretion.

1. Stress and hypothermia cause TRH to be released from neurons within the hypothalamus. It passes through the hypothalamohypophysial portal system to the anterior pituitary. 2. TRH causes cells of the anterior pituitary to secrete TSH, which passes through the general cirulation to the thyroid gland. 3. TSH causes increased synthesis and release of T3 and T4 into the general circulation. 4. T3 and T4 act on target tissues to produce a response. 5. T3 and T4 also have an inhibitory effect on the secretion of TRH from the hypothalamus and TSH from the anterior pituitary.

List the steps of aldosterone affecting blood pressure.

1.Changes in blood pressure indirectly affect the rate of aldosterone secretion. Low blood pressure causes the release of a protein molecule called renin form the kidney. 2. Renin, which acts as an enzyme, causes a blood protein called angiotensinogen to be converted to angiotensin I. 3. Then, a protein called angiotensin-converting enzyme causes angiotensisn I to be converted to angiotensin II. 4. Angiotensin II causes smooth muscle in blood vessels to constrict, and angiotensin II acts on the adrenal cortex to increase aldosterone secretion. Aldosterone causes retention of Na+ and water, which leads to an increase in blood volume (figure 10.20). Both Blood vesssle constriction and increased blood volume help raise blood pressure.

What does cortisol cause the liver to do?

1.Cortisol causes the liver to convert amino acids to glucose , and it acts on adipose tissue, causing lipids to be broken down to fatty acids. 2. The glucose and fatty acids are released into the blood, taken up by tissues, and used as a source of energy. Cortisol also causes proteins to be broken down to amino acids, which are then released into th eblood.

What steroid is closely related to cortisol?

A closely related steroid, cortisone, or other similar drugs are often given to reduce inflammation caused by injuries.

What does the lack of ADH secretion cause?

A lack of ADH secretion casues diabetes insipidus, which is the production of a large amount of dilute urine. The consequences of diabetes insipidus are not obvious until the condition becomes severe, producing many liters of urine each day. The large urine volume causes an increase in the concentration of the body fluids and the loss of important electrolytes, such as Ca2+, Na+, and K+. The lack of ADH secretion may be familiar to some who have ever had alcohol to drink. The diuretic actions of alcohol are due to its inhibition of ADH secretion.

Describe a second messenger system.

A second messenger is a chemical produced inside a cell once a hormone or another chemical messenger binds to certain membrane receptors. The second messenger then activates specific cellular processes inside the cell in response to the hormone. In some cases, this coordinated set of events is referred to as a second messenger system.

What increases the secretion of both LH and FSH?

A single releasing horomone from the hypothalamus increases the secretion of both LH and FSH.

What is pituitary dwarf?

A young person suffering from a deficiency of growth hormone remains small, although normally proportioned, and is called a pituitary dwarf. This condition can be treated by administering growth hormone. Because GH is a protein, it is difficult to produce artificially using conventional techniques.

Why is ACTH require?

ACTH is required to keep the adrenal cortex from degenerating.

What else do ACTH molecules also bind to?

ACTH molecules also bind to melanocytes int he skin and increase skin pigmentation.

What happens when too much ADH is released?

ADH can also cause blood vessels to constrict when released in large amounts. Consequently, it is sometimes also called vasopressin.

Explain the process of Adrenocorticotropic hormone molecules binding to receptors to regulate the secretion of cortisol.

Adrenocorticotropic hormone (ACTH) molecules from the anterior pituitary bind to membrane-bound receptors and regulate the secretion of cortisol from the adrenal cortex in the process depicted in figure 10.21.

What does Adrenocorticotropic hormone do?

Adrenocorticotropic hromone (ACTH) binds to membrane-bound receptors on cells in the cortex of the adrenal glands. ACTH increases the secretion of a hormone from the adrenal cortex called cortisol, also called hydrocortisone.

What does Aldosterone cause?

Aldosterone causes Na+ and water to be retained in the body and increases the rate at which K+ is eliminated.

What is a major class of mineralocorticoids?

Aldosterone is the major hormone of this class. Aldosterone rimarily binds to receptor molecules in the kidney, but it also affects the intestine, sweat glands, and salivary glands.

What do Alpha cells secrete?

Alpha cells secrete glucagon.

What is hypoparathyroidism?

An abnormally low rate of PTH secretion, called hypoparathyroidism, can result from injury to or th eusrgical removal of the thyroid and parathyroid glands.

What is an Autocrine chemical messenger?

An autocrine chemical messenger stimulates the cell that originally secreted it, and sometimes nearby cells of the same type. Good examples of autocrine chemical mssnegers are those secreted by white blood cells during an infection.

What is hyperthyroidism?

An elevated rate of thyroid hormone secretion, known as hyperthyroidism, causes an increased metabolic rate, etreme nervousness, and chronic fatigue.

What do androgens do?

Androgens stimulate the development of male sexual characterstics.

What have animal studies shown?

Animal studies have demonstrated that the amount of availbale light controsl the rate of melatonin secretion. In many animals, short day length causes an increase in melatonin secretion, whereas longer day length causes a decrease in melatonin secretion. Some evidence suggests that melatonin play an important role in the onset of puberty in humans.

What is antidiuretic hormone?

Antidiuretic hromone (ADH) binds to membrane-bound receptors and increases water reabsorption by kidney tubules. This results in less water lost as urine.

What is acromegaly?

As a result, the facial features and hands become abnormally large, condition called acromegaly.

What are prostaglandins used for?

Because of their action on the uterus, prostaglandins have been used medically to initiate abortion.

What do beta cells secrete?

Beta cells secrete insulin.

What happens when prolonged reabsorption occurs?

Blood Ca2+ levels can be maintained within a normal range, but prolonged reabsorption of bone results in reduced bone density, as manifested by soft, flexible bones that are easily deformed in young people and porous, fragile bones in older people.

What influences aldosterone secretion?

Blood levels of K+ and Na+ directly affect the adrenal cortex to influence aldosterone secretion.

What is humoral stimuli?

Blood-borne chemicals can directly stimulate the release of some hormones. These chemicals are referred to as humoral stimuli because they circulate in the blood, and the word humoral refers to body fluids, including blood.

What does Glucagon bind to?

Glucagon binds to membrane bound receptors primarily in the liver, causing the glycogen stored in the liver to be converted to glucose. The glucose is then released into the blood to increase blood glucose levels. After a meal, when blood glucose levels are elevated, glucagon secretion is reduced.

What is Glucagon?

Glucagon is released from the alpha cells when blood glucose levels are low.

What are Gonadotropins?

Gonadotropins are hormones that bind to membrane-bound receptors on the cells of the gonads (ovaries and testes). They regulate the growth, development, and functions of the gonads.

What is graves disease?

Graves disease is a type of hyperthyroidism that resuls when the immune system produces abnormal proteins that are similar in structure and function to TSH. Graves disease is often accompanined by bulging of the eyes, a condition called exophthalmia.

What is growth hormone?

Growth hormone (GH) stimulates the growth of bones, muscles, and other organs by increasing gene expression. It also resists protein breakdown during periods of food deprivation and favors lipid breakdown.

Describe the endocrine system function Heart rate and blood pressure regulation.

Heart rate and blood pressure regulation. The endocrine system helps prepare the body for physical activity.

Adrenal cortex

Hormone: Adrenal androgens Target Tissue: Most tissues Response: Insignificant in males; increase female sexual drive, growth of pubic and axillary hair.

Anterior Pituitary Gland

Hormone: Adrenocorticotropic hormone (ACTH) Target Tissue: Adrenal cortex Resonse: Increases secretion of gluccocorticoid horomones, such as cortisol; increases skin pigmentation at high concentrations.

Posterior Pituitary Gland

Hormone: Antidiuretic hormone (ADH) Target Tissue: Kidney Response: Conserves water; constricts blood vessels.

Thyroid gland

Hormone: Calcitonin Target Tissue: Primarily bone Response: Decreases rate of bone breakdown; prevents large increase in blood Ca2+ levels following a meal

Adrenal medulla

Hormone: Epinephrine mostly, some norepinephrine Target Tissue: Heart, blood vessels, liver, fat cells Response: Increases cardiac output; increases blood flow to skeletal muscles and heart; increases release of glucose and fatty acids into blood; in general, prepares body for physical activity.

Ovaries

Hormone: Estrogens, progesterone Target Tissue: Most tissues Response: Aid in uterine and mammary gland development and function, external genitalia structure, secondary sexual characteristics, sexual behavior, menstrual cycle

Pancreas

Hormone: Glucagon Target Tissue: Primarily liver Response: Increases breakdown of glycogen and release of glucose into the circulatory system

Anterior Pituitary Gland

Hormone: Growth hormone Target Tissue: Most tissues Response: Increases gene expression, breakdown of lipids, and release of fatty acids from cells; increases blood glucose levels.

Pancreas

Hormone: Insulin Target Tissue: Especially liver, skeletal muscle, adipose tissue Response: Increases uptake and use of glucose and amino acids

Anterior Pituitary Gland

Hormone: Luteinizing hormone (LH) or interstitial cell-stimulating hormone (ICSH) Target Tissue: Ovary in females, testis in males Response: Promotes ovulation and progesterone production in ovary; promotes testosterone synthesis and support for sperm cell production in testis.

Anterior Pituitary Gland

Hormone: Melanocyte-stimulating hormone (MSH) Target Tissue: Melanocytes in skin Response: Increases melanin production in melanocytes to make skin darker in color

Pineal gland

Hormone: Melatonin Target Tissue: Among others, hypothalamus Response: Inhibits secretion of gonadotropin-releasing hormone, thereby inhibiting reproduction

Adrenal cortex

Hormone: Mineralocorticoids (aldosterone) Target Tissue: Kideys; to lesser degree, intestine and sweat glands Response: Increase rate of sodium transport into body; increase rate of potassium excretion; secondarily favor water retention.

Posterior Pituitary Gland

Hormone: Oxytocin Target Tissue: Mammary gland Response: Increases milk letdown from mammary glands

Posterior Pituitary Gland

Hormone: Oxytocin Target Tissue: Uterus Response: Increases uterine contractions

Parathyorid hormone

Hormone: Parathyorid hormone Target Tissue: Bone, kidney Response: Increases rate of bone breakdonw by osteoclasts; increases vitamin D synthesis, essential for maintenance of normal blood calcium levels.

Anterior Pituitary Gland

Hormone: Prolactin Target Tissue: Ovary and mamry gland in females, testis in males Response: Stimulates milk production and prolongs progesterone secretion following ovulation and during pregnancy in women; increases sensitivity to LH in males

Uterus, ovaries, inflamed tissues

Hormone: Prostaglandins Target Tissue: Most tissues Response: Mediate inflammatory responses; increase uterine contractions and ovulation

Testes

Hormone: Testosteron Target Tissue: Most tissue Response: Aids in sperm cell production, maintenance of functional reproductive organs, secondary sexual characteristics, sexual behavior.

Thymus

Hormone: Thymosin Target Tissue: Immune tissues Response: Promotes immune system development and function

Thyroid gland

Hormone: Thyroid hormones (thyroxine, triiodothyronine) Target Tissue: Most cells of the body Response: Increase metabolic rates, essential for normal process of growth and maturation.

Anterior Pituitary Gland

Hormone: Thyroid-stimulating hormone (TSH) Target Tissue: Thyroid gland Response: Increases thyroid hormone secretion (thyroxine and triiodothyroine)

What do hormones from the small intestine help do?

Hormones secreted from the small intestine also help regulate the rate at which food passes from the stomach into the small intestines.

Where do hormones travel?

Hormones than travel through general blood circulation to specific sites called target tissues or effectors, where they produce a coordinated response of the target tissues.

What are some hormones that bind to membrane-bound receptors?

Hormones that bind to membrane-bound receptors include proteins, peptides, some amino acid derivatives, such as epinephrine and norepinephrine, and some lipid-soluble hormones.

Adrenal cortex

Hormones: Gluccorticoids (cortisol) Target Tissue: Most tissues (e.g., liver, fat, skeletal muscle, immune tissues) Response: Increase fat and protein breakdown; increase glucose synthesis from amino acids; increase blood nutrient levels; inhibit inflammation and immune response

What happens if blood glucose levels are too high?

If blood glucose levels are too high, the kidneys produce large volumes of urine containing substantial amounts of glucose. Because of the rapid loss of water in the form of urine, dehydration can result.

What happens if androgen secretion is abnormally high?

If the secretion of sex hormones from the adrenal cortex is abnormally high, exaggerated male characteristics develop in both males and females. This condition is most apparent in females and in males before puberty, when the effects are not masked by the secretion of androgens by the testes.

Describe the endocrine system function immune system regulation.

Immune system regulation. The endocrine system helps control the production and functions of immune cells.

What do the parafollicular cells of the thyroid gland secrete?

In addition to secreting thyroid hormones, the parafollicular cells of the thyroid gland secrete a hormone called calcitonin.

How does androgen influence females?

In adult females, the adrenal androgens influence the female sex drive.

Where is androgen secreted in adult males?

In adult males, most androgen are secreted by the testes.

What does lack of thyroid hormones result in?

In adults, the lack of thyroid hormones results in a decreased metabolic rate, sluggishness, a reduced ability to performe routine tasks, and myxedema, which is the accumulation of fluid and other molecules in the subcutaneous tissue.

What is cretinism?

In infants, hypothyroidism can result in cretinism, characterized by mental retardation, short stature, and abnormally formed skeletal structures.

Describe hormones of pregnant women.

In pregnant women, the placenta is an important source of hormones that maintain pregnancy and stimulate breast development. These hormones are estrogen, progesteron, and human chorionic gonadotropin, which is similar in structure and function to LH.

What is the response to low blood Ca2+ levels?

In response to low blood Ca2+ levels, nerves and muscles become excitable and produce spontaneous action potentials that cause frequent muscle cramps or tetanus. Severe tanus can affect the respiratory muscles; breathing stops, resulting in death.

What does cortisol do in response to stressful conditions?

In response to stressful conditions, cortisol is secreted in larger than normal amounts; thus, it aids the body by providing energy sources for tissues. However, if stressful conditions are prolonged, the immune system can be suppressed enough to make the body susceptible to stress-related conditions.

What are the two sex hormones of females?

In the female, two main classes of sex hormones, secreted by the ovaries affect sexual characteristics: estrogen and progesterone. Together, these hormones contribute to the development and function of femal reproductive structures and other female sexual characteristics.

What do TSH stimulate?

In turn, TSH stimulates the secretion of thyroid hormones from the thyroid gland. Small fluctuations in blood TSH levels occur on a daily basis, with a small increase at night. Increasing blood levels of TSH increase the synthesis and release of TSH decrease the synthesis and release of thyroid hormones.

Explain the importance of regulating blood glucose levels.

It is very important to maintain blood glucose levels within a normal range. A below-normal blood glucose level causes the nervous system to malfunction because glucose is the nervous system's main source of energy. When blood glucose decreases, other tissues rapidly break down lipids and proteins to provide an alternative energy source. As lipids are broken down, the liver converts some of the fatty acids to acidic ketones, which are released into the blood. When blood glucose levels are very low, the breakdown of lipids can cause the release of enough fatty acids and ketons to reduce the pH of the body fluids below normal, a condition called acidosis. The amino acids of proteins are broken down and used by th eliver to synthesize glucose.

What do LH and FSH do for ovaries and the testes?

LH and FSH stimulate the secretion of hormones from the ovaries and testes. Releasing hormones controls the rate of LH and FSH secretion in males and females. LH and FSH, in turn, control the secretion of hormones from the ovaries and testes.

What do lipid-soluble hormones bind to?

Lipid-soluble hormones bind to nuclear receptors. Lipid-soluble hormones tend to be relatively small. They diffuse through the plasma membrane and bind to nuclear receptors, which are most often found in the cell nucleus. Lipid-soluble hormones carry out gene transcription when activated a nuclear receptor.

What causes release of renin?

Low blood pressure causes the release of a protein moleucle called renin from the kidney.

What is Melanocyte-stimulating hormone?

Melanocyte-stimulating hormone (MSH) binds to membrane-bound receptors on melanocytes and causes them to synthesize melanin.

Describe the function of the endocrine system metabolism.

Metabolism. The endocrine system regulates the rate of metabolism, the sum of the chemical changes that occur in tissues.

What are neurotransmitters?

Neurotransmitters are chemical messengers secreted by neurons that activate an adjacent cell, whether it is another neuron, a muscle cell, or a glandular cell. Neurotransmitters are secreted into a synaptic cleft, rather than into the bloodstream (see chapter 8). Therefore, in the strictest sense neurotransmitters are paracrine messengers, but for our purposes it is most appropriate to consider them as a separate category.

What are the organs in the body with the richest blood supply?

Not surprisingly, the organs in the body with the richest blood supply are endocrine glands, such as the adrenal gland and the thyroid gland.

What does thyroxine contain?

One thyroid hormone, called thyroxine contains four iodine atoms and is abbreviated T4.

What is oxytocin?

Oxytocin binds to membrane-bound receptors, and causes contraction of the smooth muscle cells of the uterus as well as milk letdown from the breasts in lactating women.

What are the effects of PTH?

PTH has many effects: 1. PTH binds to membrane-bound recepotrs of renal tubule cells, which increases active vitamin D formation. Vitamin D causes the epithelial cells of the intestine to increase Ca2+ absorption. 2. PTH binds to receptors on osteoblasts. Substances released by the osteoblasts increase osteoclast activity and cause reabsorption of bone tissue to release Ca2+ into the circulatory system. 3. PTH binds to receptors on cells of the renal tubules and decreases the rate at which Ca2+ is lost in the urine. 4. PTH acts on its target tissues to raise blood Ca2+ levels to normal.

What are Paracrine chemical messengers?

Paracrine chemical messengers act locally on nearby cells. These chemical messengers are secreted by one cell type into the extracellular fluid and affect surrounding cells of a different cell type into the extracellular fluid and affect surrounding cells of a different type. An example of a paracrine chemical messenger is histamine released by certain white blood cells during allergic reactions. Histamine stimulates vasodilation in nearby blood vessels.

What is growth hormone influenced by?

Part of the effect of growth hormone is influenced by a group of protein hormones called insulin-like growth factors (IGFs), or somatomedins. Growth hormone increases IGF secretion form tissues such as the liver, and the IGF molecules bind to receptors on the cells of tissues such as bone and cartilage, where they stimulate growth.

Describe androgen secretion in males and females.

Small amounts of androgens are secreted from the adrenal cortex in both males and females.

What is somatostatin?

Somatostatin is released by teh delta cells in response to food intake Somatostatin inhibit the secretion of insulin and glucagona dn inhibits gastric tract activity.

What do some prostaglandins cause?

Some prostaglandins cause relaxation of smooth muscle, such as dilation of blood vessels. Others cause contraction of smooth muscle, such as contraction of the uterus during the delivery of a baby.

What does Follicle-stimulating hormone do?

Stimulates the development of follicles in the ovaries and sperm cells in the testes.

What do T cells do?

T cells help protect the body against infection by foreign organisms.

What do water-soluble hormones bind to?

Water-soluble hormones bind to membrane-bound receptors. Water-soluble hormones are polar molecules and cannot pass through the plasma membrane. Instead, they interact with membrane-bound receptors, which are proteins that extend across the plasma membrane, which are proteins that extend across the plasma membrane, with their hormone-binding sites exposed on the plasma membrane's outer surface.

What happens when blood glucose levels decline?

When blood glucose levels decline, cortisol secretion increases. The low blood glucose acts on the hypothalamus to increase the secretion of the ACTH-releasing hormone, which, in turn, stimulates ACTH secretion from the anterior pituitary. ACTH then stimulates cortisol secretion. Without ACTH, the adrenal cortex atrophies and loses its ability to secret cortisol

Describe target cells that synthesize new protein molecules.

Target cells that synthesize new protein molecules in response to hormonal stimuli normally have a latent period of several hours between the time the hormones bind to their receptors and the time responses are observed. During this latent period, mRNA and new proteins are synthesized. Hormone-recepto complexes are eventually degraded within the cell, limiting the length of time hormones influence the cells' activities, and the cells slowly return to their previous funcitonal states.

Describe aspirin and its effect on prostaglandin synthesis.

The ability of aspirin and related substances to reduce pain and inflammation, to help prevent th painful cramping of uterine smooth muscle, and to treat headache is a result of their inhibitory effect on prostaglandin synthesis.

What happens when too little TSH is secreted?

When too little TSH is secreted, the thyroid gland decreases in size and secrete too little thyroid hormone.

What does the adrenal cortex secrete?

The adrenal cortex secretes three classes of steroid hormones: mineralocorticoids, glucocorticoids, and androgens. The molecules of all three classes of steroid hormones enter their target cells and bind to nuclear receptor molecules. However, the hormones and the receptors of each class have unique structural and functional characteristics.

What are the adrenal glands?

The adrenal galnds are two small glands located superior to each kidney.

What is the adreanl gland much more sensitive to?

The adrenal gland is much more sensitive to changes in blood K+ levels than to changes in blood Na+ levels.

What happens when too much TSH is released?

When too much TSH is secreted, the thyroid gland enlarges and secretes too much thyroid hormone.

What would happen without LH and Fash?

Without LH and FSH, the ovaries and testes decrese in size, no longer produce oocytes or sperm cells, and no longer secrete hormones.

What is hypothyrodism?

Without a normal rate of thyroid hormone secretion, growth and evelopment cannot proceed normally. A lack of thyroid hormones is called hypothyroidism.

What does the adrenal medulla release epinephrine and norepinephrine in response to?

The adrenal medulla releases epinephrine and norepinephrine in response to stimulation by the sympathetic nervous system, which becomes most active when a person is excited or physically active. These hormones bind to membrane-bound receptors in their target tissues.

What is the hypothalamic-pituitary portal system?

The capillary beds and veins that transport the releasing and inhibiting hormones are called the hypothalamic-pituitary portal system.

What does the endocrine part of the pancreas consist of?

The endocrine part of the pancreas consists of pancreatic islets, which are dispersed throughout the exocrine portion of the pancreas.

What is the endocrine system composed of?

The endocrine system is composed of endocrine glands and specialized endocrine cells located throughout the body.

What are mineralocorticoids?

The first class of hormones, secreted by the outer layer of the adrenal cortex, the mineralocorticoids, helps regulate blood volume and blood levels of K+ and Na+.

What does luteinizing hormone do in males?

stimulates interstitial cells of the testes to secrete the sex hormone testosterone and thus is sometimes referred to as interstitial cell-stimulating hormone (ICSH).

What is the second class of hormones secreted by the middle layer of the adrenal corte?

The glucocorticoids helps regulate blood nutrient levels.

Where and why is insulin released?

The hormone insulin is released from the beta cells primarily in response to the elevated blood glucose levels and increased parasympathetic stimulation associated with digestion of a meal.

What is the hypothalamus?

The hypothalamus is an important autonomic nervous system and endocrine control center of the brain located inferior to the hypothalamus.

What hormones help produce thyroid-stimulating hormone?

The hypothalamus secretes TSH-releasing hormone, also known as TRH, whihc travels to the anterior pituitary and stimulates the secretion of thyroid-stimulating hormone.

What do the islets secrete?

The islets secrete three hormones--insulin, glucagon, and somatostatin--which help regulate the blood levels of nutrients, especially glucose.

What do the kineys secrete?

The kidneys secrete the hormone erythropoietin in response to reduced oxygen levels in the kidney.

What do low blood levels of PTH lead to?

The low blood levels of PTH lead to reductions in th erate of bone reabsorption and the formation of vitamin D. As a result, blood Ca2+ levels decrease.

What is the main function of the thyroid gland?

The main function of the thyroid gland is to secrete thyroid hormones, which bind to nuclear receptors in cells and regulate the rate of metabolism in the body.

Wha is the main male sex hormone?

The main sex hormone in the male is testosterone, which is secreted by the testes. It is responsible for the growth and development of the male reproductive structures, muscle enlargement, the growth of body hair, voice changes, and the male sexual drive.

What is the major glucocorticoid hormone?

The major glucocorticoid hormone is cortisol, which increases the breakdown of proteins and lipids and increases their conversion to forms of energy the body can use.

What are the major target tissues for insulin?

The major target itssues for insulin are th liver, adipose tissue, muscles, and the area of the hypothalamus that controls appetite, called the satiety center.

What does triiodothyronine contain?

The other thyroid hormone, triiodothyronine contains three iodine atoms and is abbreviated T3.

What do the ovaries of the female do?

The ovaries of the female produce oocytes.

What does calcitonin bind to?

Calcitonin binds to membrane-bound receptors of osteoclasts and reduces the rates of Ca2+ resaborption (breakdown) from bone by inhibiting the osteoclasts.

Why is calcitonin secreted?

Calcitonin is secreted if the blood concentratio of Ca2+ becomes to high, and it causes Ca2+ levels to decrease to their normal range.

What does calcitonin prevent?

Calcitonin may prevent blood Ca2+ levels from becoming overly elevated following a meal that contains a high concentration of Ca2+. Calcitonin helps prevent elevated blood Ca2+ levels, but a lack of calcitonin secretion does not result in a prolonged increase in those levels.

What does luteinizing hormone in females do?

Causes the ovulation of oocytes and the secretion of the sex hormones estrogen and progesterone from the ovaries.

Describe cells in the lining of the stomach and small intestine.

Cells in the lining of the stomach and small intestine secrete hormones that stimulate the production of digestive juices from the stomach, pancreas, and liver. This secretion occurs when food is present in the digestive system, but not at other times.

What else affects the rate of aldosterone secretion?

Changes in blood pressure indirectly affect the rate of aldosterone secretion.

What is given to assist in childbirth?

Commercial preparations of oxytocin, known as Pitocin, are given under certain conditions to assist in childbirth and to constrict uterine blood vessels following childbirth.

Describe the endocrine system function control of blood glucose and other nutrients.

Control of blood glucose and other nutrients. The endocrine system regulates the levels of blood glucose and other nutrients in the blood.

Describ the endocrine system function control of food intake and digestion.

Control of food intake and digestion. The endocrine system regulates the level of satiety (fullness) and the breakdown of food into individual nutrients.

Describe the endocrine system function control of reproductive functions.

Control of reproductive functions. The endocrine system controls the development and functions of the reproductive systems in males and females.

What does cortisol do?

Cortisol reduces th inflammatory and immune responses.

What can cortison reduce?

Cortisone can also reduce the immune and inflammatory responses that result from allergic reactions or abnormal immune responses, such as rheumatoid arthirits or asthma.

What do decreased insulin levels allow?

Decreased insulin levels allow blood glucose to be conserved to provide the brain with adequat glucose and to allow other tissues to metabolize fatty acids and glycogen stored in the cells.

Why does decreased insulin secretion result?

Decreased insulin secretion results from decreasing blood glucose levels and from stimulation of the pancreas y the sympathetic division of the nervous system, which occurs during physical activity.

What can stimulate an increase in PTH?

Decreasing blood Ca2+ levels stimulate an increase in PTH secretion. For example, if too little Ca2+ is consumed in the diet or if a person suffers from a prolonged lack of vitamin D, blood Ca2+ levels decrease, and PTH secretion increases. The increased PTH increases the rate of bone reabsorption.

What does decreasing thyroid hormone levels allow?

Decreasing thyroid hormone levels allow additional TSH-releasing hormone and TSH to be secreted. Because of the negative-feedback effect, the thyroid hormones fluctuate within a narrow concentration range in the blood. However, a loss of negative feedback will result in excess TSH.

What do delta cells secret?

Delta cells secret somatostatin.

Chemical Messenger: Paracrine

Description: Produced by a wide variety of tissues and secreted into extracellular fluid; has a localized effect on other tissues Example: Somatostatin, histamine, eicosanoids.

Chemical Messenger: Neurotransmitter

Description: Produced by neurons; secreted into a synaptic cleft by presynaptic nerve terminals; travels short distances; influences postsynaptic cells. Example: Acetycholine, epinephrine

Chemical Messenger: Autocrine

Description: Secreted by cells in a local area; influences the activity of the same cell or cell type from which it was secreted. Example: Eicosanoids (prostaglandins, thromboxanes, prostacyclins, leukotrienes)

Chemical Messenger: Endocrine

Description: Secreted into the blood by specialized cells; travels some distance to target tissues; results in coordinated regulation of cell function. Example: Thyroid hormones, growth hormone, insulin, epinephrine, estorgen, progesterone, testosterone, prostaglandins.

Describe the two parts of the adrenal gland.

Each adrenal gland has an inner part, called the adrenal medulla (marrow, or middle), and an outer pert, called the adrenal cortex (bark, or outer).

What is each thyroid follicle filled with?

Each thyroid follicle is filled with the protein thyroglubulin, to which thyroid hormones are attachd.

What are endocrine chemical messengers?

Endocrine chemical messengers are secreted into the bloodstream by certain glands and cells, which together consitute the endocrine system. These chemical messengers affect cells that are distant from their source.

What do endocrine glands and cells secrete?

Endocrine glands and cells secrete minute amounts of chemical messengers called hormones into the bloodstream, rather than into a duct.

What are epinephrin and norepinephrine referred to as?

Epinephrine and norepinephrine are referred to as the fight-or-flight hormones because of their role in preparing the body for vigorous physical activity.

What does Erythropoietin act on?

Erythropoietin acts on bone marrow to increase the production of red blood cells.

What are some examples of exocrine secretions?

Examples of exocrine secretions are saliva, sweat, breast milk, and digestive enzymes.

What is goiter?

Excess TSH causes the thyroid gland ot enlarge, a condition called goiter. One type of goiter develops iodine in the diet is too low. As less thyroid hormone is synthesized and secreted, TSH-releasing hormone and TSH secretion increase above normal levels and cause dramatic enlargement of the thyroid gland.

What does excess secretion of growth hormone result from?

Excess growth hormone secretion can result from hormone secreting tumors of the pituitary gland. If excess growth hormone is present before bones finish growing in length, exaggerated bone growth occurs.

What are exocrine glands?

Exocrine glands have ducts that carry their secretions to the outside of the body, or into a hollow organ, such as the stomach or intestines.

What do the parathyroid glands secrete?

The parathyroid glands secrete a hormone called parathyroid hormone (PTH), which is essential for the regulation of blood calcium levels. In fact, PTH is more important than calcitonin in regulating blood Ca2+ levels.

What is giantism?

The person becomes abnormally tall, a condition called giantism. If excess hormone is secreted after growth in bone length is complete, growth continues in bone diameter only.

What disaes results in bulging of the eyes?

Exophthalmia.

What is the pineal gland?

The pineal gland is a small, pinecone-shaped structure located superior and posterior to the thalamus of the brain.

What does the pineal gland produce?

The pineal gland produces a hormone called melatonin, which is thought to decrease the secretion of LH and FSH by decreasing the release of hypothalamic releasing hormones. Thus, melatonin inhibits the functions of the reproductive system.

Describe the pituitary gland.

The pituitary gland is also called the hypophysis. It is a small gland about the size of a pea. It rests in a depression of the sphenoid bone inferior to the hypothalamus of the brain.

Where is the pituitary gland?

The pituitary gland lies posterior to the optic chiasm and is connected ot the hypothalamus by a stalk called the infundibulm.

What is the principle hormone released from the adrenal medulla?

The principal hormone released form the adrenal medulla is epinephrine or andrenaline. Small amounts of norepinephrine are also released.

When does aldosterone secretion fluctuate?

The rate of aldosterone secretion increases when blood K+ levels increase or when blood Na+ levels decrease.

Describe the regulation of prolactin.

The regulation of prolactin secretion is complex and may involve several substances released from the hypothalamus.

What is neural stimuli?

The second type of hormone regulation invovles neural stimuli of endocrine glands. Following action potentials, neurons release a neurotransmitter into the synapse with the cells that produce the hormone.

Describe MSH.

The structure of MSH is similar to that of ACTH, and oversecretion of either hormone causes the skin to darken.

What is the study of the endocrine system known as?

The study of the endocrine system, known as endocrinology.

What do the testes of the male do?

The testes of the male produce sperm cells. Are important for developing male sex characteristics.

What are androgens?

The third class of hormones, secreted by th einner layer of the adrenal cortex, is composed of the androgens.

Give an example of a Nuclear receptor.

For example, testosterone stimulates the synthesis of proteins that are responsible for male secondary sex characteristics, such as the formation of muscle mass and the typical male body structure. The steroid hormone aldosterone affects its target cells in the kidneys by stimulating the syntehsis of proteins that increase the rate of Na+ and K+ transport. The result is a reduction in the amount of Na+ and an increase in the amount of K+ lost in the urine. Other hormones that produce responses through nuclear receptor mechanisms incude thyroid hormones and vitamin D.

Where are parthyroid glands embedded?

Four tiny parathyroid glands are embedded in the posterior wall of the thyroid gland.

What is hormonal stimuli?

The third type of regulation uses hormonal stimuli. It occurs when a hormone is secreted that, in turn, stimulates the secretion fo toher hormones.

Why is the thymus important in early life?

The thymus is most important in early life; if an infant is born without a thymus, the immune system does not develop normally, and the body is less capable of fighting infections.

What is the thymus?

The thymus lies in the upper part of the thoracic cavity. It is important in the function of the immune system.

What does the thymus secrete?

The thymus secretes a hormone called thymosin, which aids the development of white blood cells called T cells.

Describe the thyroid gland.

The thyroid gland is made up of two lobes connected by a narrow band called the isthmus. (a constriction. The lobes are located on each side of the trachea, just inferior to the larynx. The thyroid gland is one of the largest endocrine glands. It appears more red than the surrounding tissues because it is highly vascular. It is surrounded by a connective tissue capsule.

What dos the thyroid gland reqiure to synthesize thyroid hormones?

The thyroid gland requires iodine to syntehsize thyroid hormones. Iodine is taken up by the thyroid follicles.

What do thyroid hormones have on the hypothalamus and pituitary?

The thyroid hormones have a negative-feedback effect on the hypothalamus and pituitary, so that increasing levels of thyroid hormones inhibt the secretion of TSH-releasing hormone form the hypothalamus and inhibt TSH secretion fro the anterior pituitary gland.

What does the two main regulatory hormones of prolactin do?

There are two main regulatory hormones; one increases prolactin secretion and one decreases it.

What do the hormones of the adrenal medulla do?

These hormones bind to membrane-bound receptors in their target tissues. Stress and low blood glucose levels can also cause increased sympathetic stimulation of the adrenal medulla.

What is thyroid hormone secretion regulated by?

Thyroid hormone secretion is regulated by hormones from the hypothalamus and pituitary.

Where are thyroid hormones stored?

Thyroid hormones are synthesized and stored within the gland in numerous thyroid follicles, which are small spheres with walls composed of simple cuboidal epithelium.

What does Thyroid-stimulating hormone do?

Thyroid-stimulating hormone (TSH) binds to membrane bound receptors on cells of the thyroid gland and causes the cells to secrete thyroid hormone.

Describe the endocrine system function tissue development.

Tissue development. The endocrine system influences the development of tissues, such as those of the nervous system.

What does too little growth hormone secretion result from?

Too little growth hormone secretion can result from abnormal development of the pituitary gland.

What may develop in the pineal gland?

Tumors may develop in the pineal gland, which increase pineal secretions in some cases but decrease them in others.

What are the causes of Diabetes mellitus 1?

Type 1 diabetes mellitus occurs when too little insulin is secreted from the pancreas.

What are the causes of type 2 diabetes?

Type 2 diabetes mellitus is caused by insufficient numbers of insulin receptors on target cells or by defective receptors that do not respond normally to insulin.

Explain the function of Prostaglandins.

Unlike most hormones, they are usually not transported long distances in the blood but funciton mainly as autocrine or paracrine chemical signals. Thus, their effects occur in the tissues where they are produced.

Describe the endocrine system function uterine contractions and milk release.

Uterine contractions and milk release. The endocrine system regulates uterine contractions during delivery and stimulates milk release form the breasts in lactating females.

How does PTH help with vitamin D synthesis?

Vitamin D is produced from precursors in the skin that are modified by the liver and kidneys. Ultravilet light acting on the skin is required for the first stag of vitamin D synthesis, and the final stage of synthesis in the kidney is stimulated by PTH. Vitamin D can also be supplied in the diet.

Describe the endocrine system function water balance.

Water balance. The endocrine system regulates water balance by controlling solutes in the blood.

Describe the condition hyperglycemia.

In type 1 diabetes mellitus, tissues cannot take up glucose effectively, causing blood glucose levels to become very high, a condition called hyperglycemia. Because glucose cannot enter the cells of the satiety center in the brain without insulin, the satiety center respons as if there were very little blood glucose, resulting in an exaggerated appetite. The excess glucose in th eblood is excreted in the urine, making the urine volume much greater than normal. Because of excessive urine production, the person has a tendency to become dehydrated and thristy. Even though blood glucose levels are high, lipids and proteins are borken down to provide an energy source for metabolism, reusltin in the wasting away of body tissues, acidosis, and ketosis. People with this condition also exhibit a lack of energy. Insulin must be injected regularly to adequately control blood glucose levels. When too much insulin is present, as occurs when a diabetic is injected with too much insulin or has not eaten after an insulin injection, blood glucose levels become very low. The brain, which depends primarily on glucose for an energy source, malfunctions. This condition, called insulin shock, can cause disorientation and convulsions and may result in loss of consicousness.

What also stimulates insulin secretion?

Increased blood levels of certain amino acids also stimulate insulin secretion.

What does increasing blood Ca2+ levels cause?

Increasing blood Ca2+ levels cause a decrease in PTH secretion. The decreased PTH secretion leads to reduced blood Ca2+ levels. In addition, increasing blood Ca2+ levels stimulate calcitonin secretion, which also causes blood Ca2+ levels to decline.

Target Tissue: Nervous system

Insulin Responses: Has little effect except to increase glucose uptake in the satiety center Glucagon Responses: Has no effect

Target Tissue: Skeletal muscle, cardiac muscle, cartillage, bone fibroblasts, blood cells, mammary glands.

Insulin Responses: Increases glucose uptake and glycogen syntehsis; increases uptake of amino acids. Glucagon Responses: Has little effect

Target Tissue: Adipose cells

Insulin Responses: Increases glucose uptake, glycogen synthesis, lipid synthesis Glucagon Responses: High concentrations cause breakdown of lipids; probably unimportant under most conditions.

Target Tissue: Liver

Insulin Responses: Increases glycogen synthesis; increases use of glucose for energy Glucagon Responses: Causes rapid increas in the breakdown of glycogen to glucose and release of glucose into th eblood; increases th eformation of glucose from amino acids and, to some degree, from lipids, increases metabolism of fatty acids.

Explain how Insulin and glucagon regulate blood glucose levels.

Insulin and glucagon together regulate blood glucose levels. When blood glucose levels increase, insulin secretion increases, and glucagon secretion decreases. When blood glucose levels decrease, the rate of insulin secretion declines, and the rate of glucagon secretion increases. Other hormones, such as epinephrine, cortisol, and growth hormone, also maintain blood levels of nutrients. When blood glucose levels decrease, these hormones are secreted at a greater rate. Epinephrine and cortisol cause the breakdown of protein and lipids and the synthesis of glucose to help increase blood levels of nutrients. Growth hormone slows protein breakdown and favors lipid breakdown.

What does insulin bind to?

Insulin binds to membrane-bound receptors and, either directly or indirectly, increases the rate of glucose and amino acid uptake in these tissues. Glucose is converted to glycogen or lipids, and the amino acids are used to synthesize protein.

Describe the endocrine system function Ion regulation.

Ion regulation. The endocrine system regulates the solute concentration of the blood.

What is Prolactin

Prolactin binds to membrane-bound receptors in cells of the breast, where it helps promote development of the breast during pregnancy and stimulates the production of milk following pregnancy.

What role does prostaglandins play in?

Prostaglandins also play a role in inflammation. They are released by damaged tissues and cause blood vessel dilation, localized swelling, and pain.

Where are prostaglandins distributed?

Prostaglandins are widely distriuted in tissues of the body, where they function as intercellular signals.

Describe prostaglandins produced by platelets?

Prostaglandins produced by platelets appear to be necessary for normal blood clotting.

What does reduced ADH result in?

Reduced ADH release from the posterior pituitary results in large amounts of dilute urine.

What are the two regulatory hormones of MSH.

Regulation of MSH is not well understood, but there appear to be two regulatory hormones from the hypothalamus-- one that increases MSH secretion and one that decreases it.

What do responses to hormones from the adrenal medulla reinforce?

Responses to hormones from the adrenal medulla reinforce the effect of the sympathetic divsion of the autonomic nervous system. Thus, the adrenal medulla and the sympathetic divison function together to prepare the body for physical activity and to produce the fight-or-flight response and many other responses to stress.