Ch. 18: Endocrine System

Adrenal gland hormones

*Adrenal Cortex - steroid hormones. -Mineralocorticoids -Glucocorticoids -Androgens *Adrenal Medulla - 3 catecholamine hormones. -Norepinephrine= Nonadrenaline= Neurotransmitters. -Epinephrine= Adreilanine -Dopamine.

What are the functions of hormones?

*Help regulate: -Chemical composition and volume of the internal environment (interstitial fluid). -Metabolism and energy balance. -Contraction of smooth and cardiac muscle fibers. -Glandular secretions. Some immune system activities. *Control growth and development. *Regulate operation of reproductive systems. *Help establish circadian rhythms.

Action of water-soluble hormones

-Are the first messenger. They activate the second messenger i.e. cyclic AMP (cAMP). -This initiates a cascade of events within the cell that produces millions of enzymes to catalyze reactions. -Phosphodiesterase inactivates cAMP.

Functions of hGHs and IGFs (insulin-like growth factor)

-IGFs cause cells to grow and multiply. -They help to maintain the mass of muscles and bones. -They promote healing of injuries and tissue repair. -They enhance lypolysis in adipose tissue.

Down-regulation

-If a hormone is present in excess, the number of target cell receptors may decrease. -Down-regulation decreases the responsiveness of the target cell to the hormone.

Time To Onset Of Action In Nervous & Endocrine Systems

-In the nervous system, action typically occurs within milliseconds of neurotransmitter release. -In the endocrine system, action can take seconds to hours to days to occur after release of the hormone.

What are the actions of the thyroid hormones?

-Increase basal metabolic rate (BMR). -Stimulates synthesis of Na+ / K+ ATPase -Calorigenic effect. Helps to regulate body temperature. -Regulate metabolism: Protein synthesis, Increase the use of glucose and fatty acids for ATP, Increase lypolysis. -Accelerate body growth, especially of the nervous system. -Enhances actions of the catecholamines (norepinephrine and epinephrine). In hyperthyroidism there is an increased heart rate, more forceful heartbeats, and increased blood pressure.

How do epinephrine and norepinephrine augment the flight or fight response?

-Increase the heart rate and force of contraction. -Dilates the airways in the lungs. -Shunts blood to heart, liver, skeletal muscles, and adipose tissue. -Increases blood levels of glucose and fatty acids.

Effects of glucocorticoids

-Increase the rate of protein breakdown. -Stimulates glucose formation by breaking down glycogen stores and through gluconeogenesis. -Stimulates lypolysis. -Resistance to stress by supplying ATP and raising BP in cases of severe blood loss. -Anti-inflammatory effects - inhibit WBCs (also slows wound healing). -Depression of immune responses (utilized with organ transplant recipients).

Hormone Receptors

-Only target cells for a given hormone have specific receptors that bind and recognize that hormone. -A target cell can have anywhere between 2000 and 100,000 receptors for a particular hormone. -Receptors are constantly being synthesized and broken down to meet the needs of the body.

How is hormone secretion regulated?

-Signals from the nervous system. -Chemical changes in the blood. -Other hormones.

Types Of Anterior Pituitary Cells & Their Hormones

-Somatotrophs - secretes human growth hormone (hGH) or somatotropin, which stimulates tissues to secrete insulinlike growth factors (IGFs). -Thyrotrophs - secrete thyroid-stimulating hormone (TSH) or thyroptropin. -Gonadotrophs: secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH) which act on the gonads. They stimulate the secretion of estrogen and progesterone and the maturation of oocytes in the ovaries. They stimulate the secretion of testosterone and sperm production in the testes. -Lactotrophs: secrete prolactin (PRL), which initiates milk production. -Corticotrophs: secrete adrenocorticotropic hormone (ACTH) or corticotropin, which stimulates the adrenal cortex to secrete glucocorticoids.

Responsiveness of the target cell depends on...

-The hormone's concentration. -The number of the hormone receptors on the target cell. -Influences exerted by other hormones. (working together or opposing each other)

What does "sypersystem" mean?

-The nervous and endocrine systems function together. -Parts of the nervous system stimulate or inhibit the release of hormones. -Hormones can promote or inhibit the release of nerve impulses.

Types of target cells

-The nervous system acts upon muscle cells (smooth, cardiac, and skeletal), glands, and other neurons. -The endocrine system acts upon virtually all cells of the body.

What are the mediator molecules used in nervous vs. endocrine systems?

-The nervous system utilizes NEUROTRANSMITTERS to control body functions. -The endocrine system utilizes HORMONES to control body functions.

Site Of Mediator Action In Nervous & Endocrine Systems

-The neurotransmitters perform their action CLOSE to the site of release. -The hormones usually perform their action FAR from their site of release.

What is the purpose of estrogen and progesterone along with FSH and LH in the female body?

-To regulate the menstrual cycle, maintain pregnancy, and prepare the mammary glands for lactation. -Maintain the feminine secondary sex characteristics (larger breasts and hips).

What is the purpose of testosterone in the male body?

-To regulate the production of sperm. -Stimulates the production of male secondary sex characteristics (beard growth and deepening of the voice).

Action of Lipid-Soluble Hormones

-Turn specific genes of the nuclear DNA on or off. -This directs the synthesis of a new protein (often an enzyme). -These new proteins alter the cells activity.

Which of the following comparisons are TRUE? 1. Nerve impulses produce their effects quickly; hormonal responses generally are slower. 2. Nervous system effects are brief; endocrine system effects are longer lasting. 3. The nervous system controls homeostasis through mediator molecules called neurotransmitters; the endocrine system works through mediator molecules called hormones. 4. The nervous system can stimulate or inhibit the release of hormones; some hormones are released by neurons as neurotransmitters. 5. Neurotransmitters transmit impulses directly; hormones must bind to receptors on or in target cells in order to exert their effects.

1, 2, 3, 4

Select the true statements. Hormones-- 1. generally utilize negative feedback mechanisms to regulate their secretion 2. will only affect target cells far removed from the hormone-producing secretory cells 3. must bind to transport proteins in order to circulate in the blood 4. may be released in low concentrations but can produce large effects in the target cells because of amplification 5. can regulate the responsiveness of the target tissue by controlling the number of receptor sites for the hormone

1, 4, 5

In order of occurrence, what are the 3 stages of the stress response or general adaptation syndrome?

1. fight or flight response 2. resistance reaction 3. exhaustion

Select the true responses . The pituitary gland -- 1. is located in the cribriform plate of the ethmoid bone 2. is linked to the hypothalamus by the infundibulum 3. has a posterior portion that contains axon terminals from hypothalamic neurosecretory cells 4. produces releasing and inhibiting hormones 5. has a vascular connection with the hypothalamus known as the hypophyseal portal system

2, 3, 5

Place in correct order the action of a water-soluble hormone on its target cell. 1. Adenlyte cyclase is activated, catalyzing the conversion of ATP to cAMP. 2. Enzymes catalyze reactions that produce a physiological response attributes to the hormone. 3. The hormone binds to a membrane receptor. 4. Activated protein kinases phosphorylate cellular proteins. 5. The hormone-receptor complex activates G proteins. 6. Cyclic AMP activates protein kinases.

3. The hormone binds to a membrane receptor. 5. The hormone-receptor complex activates G proteins 1. Adenlyte cyclase is activated, catalyzing the conversion of ATP to cAMP. 6. Cyclic AMP activates protein kinases. 4. Activated protein kinases phosphorylate cellular proteins. 2. Enzymes catalyze reactions that produce a physiological response attributes to the hormone.

-The paired glands lie superior to each kidney. -Consists of the adrenal cortex (80-90% of the gland) and the adrenal medulla. -Highly vascularized.

Adrenal glands

-Controls secretion of cortisol and other glucocorticoids by the cortex of the adrenal gland. -Corticotropin-releasing hormone (CRH) from the hypothalamus stimulates secretion of this hormone. -Glucocorticoids cause inhibition of CRH and of this hormone through negative feedback systems.

Adrenocorticotropic Hormone (ACTH)

Pass from secretory cells that make them into the interstitial fluid and then into the blood. Most hormones are of this type. These type of hormones linger longer.

Circulating hormones

The study of the science of endocrine glands, function of endocrine glands, diagnosis of endocrine disorders and treatment of endocrine disorders.

Endocrinology

suppresses release of FSH

Estrogens in females and testosterone in males suppresses release of FSH through negative feedback systems.

Exocrine glands vs. endocrine glands

Exocrine glands: secrete their products into ducts that carry secretions into body cavities, into the lumen of an organ, or to the outer surface of the body. (includes Sudoriferous (sweat), Sebaceous (oil), Mucous, Digestive.) Endocrine glands: secrete their hormones into the interstitial fluid surrounding the secretory cells. Includes: Pituitary. Thyroid. Parathyroid. Adrenal. Pineal. Other organs that secrete hormones: Hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, SI, skin, heart, adipose tissue, & placenta.

T or F: If the effect of two or more hormones acting together is greater than the sum of each acting alone, then the two hormones are said to have a permissive effect.

False

Hormones of Pancreatic Islet

Glucagon Insulin Somatostatin Pancreatic polypeptide

What two hypothalamic hormones control the release of hGH?

Growth hormone releasing hormone (GHRH): -Stimulated by hypoglycemia. -Inhibited by hyperglycemia. Growth hormone inhibiting hormone (GHIH): -Stimulated by hyperglycemia. -Inhibited by hypoglycemia.

-Somatotropin or human growth hormone (hGH) -Adrenocorticotropic hormone (ACTH)/corticotropin -Thyroid stimulating hormone (thyrotropin) -Follicle stimulating hormone -Luteinizing hormone -Prolactin -Melanocyte-stimulating hormone

Hormones of the Anterior Pituitary

-Serves as a major integrating link between the nervous system and the endocrine system. -Painful, stressful, and emotional experiences cause changes in activity. -Synthesizes at least 9 different hormones. Regulates the pituitary gland.

Hypothalamus

Inhibits secretion of FSH

Inhibin

What is the regulation Of Glucagon & Insulin Secretion

Insulin allows glucose to diffuse into cells, increases amino acid uptake by cells, and increaes fatty acid uptake by cells. This facilitates glucose conversion into glycogen (glycogenesis), synthesis of proteins, and synthesis of fatty acids (lipogenesis).

act locally on neighboring cells or on the same cells that secreted them without first entering the bloodstream. Are usually inactivated quickly. Includes paracrines and autocrines. Ex. Interleukin 2 (IL-2) -released by helper T cells during immune responses. -It acts on nearby immune cells (paracrine) and on itself (autocrine). -This generates more helper T cells and boosts the immune response.Local hormones

Local hormones

What is the control Of Secretion By The Anterior Pituitary (adenohypophysis)?

Negative feedback loops from hormones released from target glands decrease the release from the anterior pituitary gland.

Gonads

Ovaries: -Produce steroid hormones Estrogens & Progesterone. -Produce inhibin. -Produce relaxin. Testes: -Produce testosterone (an androgen). -Produce inhibin.

-Both an endocrine and exocrine gland. -Have 4 major cell types: Alpha (A) cells - secrete glucagon. Beta (B) cells - secrete insulin. Delta (D) cells - secretes somatostatin (identical to growth hormone inhibiting hormone). F cells - secrete pancreatic polypeptide.

Pancreatic Islets (a.k.a. islets of Langerhans)

the action of a 2nd hormone is required for the 1st hormone to take effect. ex. Thyroid hormones (2nd) allow epinephrine to stimulate lipolysis.

Permissive effect

increases the flexibility of the pubic symphisis during pregnancy and helps dilate the cervix during labor and delivery.

Relaxin

in the form of drugs can block the receptors from naturally occurring hormones

Synthetic hormones

Hormones of the thyroid gland

T3 (triiodothyronine), T4 (thyroxine), calcitonin

Duration Of Action In Nervous & Endocrine Systems

The actions tend to be briefer in duration in the nervous system and longer in duration in the endocrine system.

-Located behind the sternum between the lungs. -Hormones produced - thymosin, thymic humoral factor (THF), thymic factor (TF), amd thymopoeietin. -Promotes the maturation of T cells and may retard the aging process.

Thymus

T or F: In the direct genera activation method of hormone action, the hormone enters the target cell and binds to an intracellular receptor.. The activated receptor-hormone complex then alters gene expression to produce the protein that causes the physiological responses that are characteristics of the hormone.

True

-When a hormone (or neurotransmitter) is deficient, the number of receptors may increase. -Makes a target cell more receptive to a specific hormone

Up-regulation

Are transported in their "free" form (not attached to plasma proteins). The receptors are located within the plasma membrane of the target cells. Includes -Amine hormones. -Peptide hormones and protein hormones. -Eicosanoid hormones: Prostaglandins and Leukotrienes.

Water soluble hormones

The class of adrenal gland hormones that provides resistance to stress, produces anti-inflammatory effects, and promotes normal metabolism to ensure adequate quantities of ATP is a. glucocorticoids b. mineralcorticoids c. androgens d. catecholamines e. gonadocorticoids

a. glucocorticoids

-regulates homeostasis of sodium and potassium ions -Promotes the secretion of H+ in the urine to regulate acid-base balance. Prevents acidosis (pH below 7.35). -Renin-angiotensin-aldosterone (RAA) pathway controls the secretion of aldosterone (Controls blood pressure).

aldosterone (cortex)

-stimulates growth of axillary and pubic hair -Contributes to libido and provides a source of estrogens after menopause in females. -ACTH stimulates its secretion.

androgens

one hormone opposes the actions of another. ex. Insulin promotes synthesis of glycogen and glucagon stimulates breakdown of glycogen.

antagonistic effect

decreases urine production & causes the kidneys to return more water to the blood.

antidiuretic hormone (ADH)

act on the same cell that secreted them

autocrines

-decreases blood Ca2+ level -inhibits the action of osteoclasts. -accelerates the uptake of calcium and phosphates into the bone matrix.

calcitonin

regulates metabolism and resistance to stress

cortisol

Types of glucocorticoids

cortisol (hydrocortisone), cortisone, corticosterone

Which of the following is not a category of water-soluble hormones? a. peptides b. amines c. eicosanoids d. steroids e. proteins

d. steroids

Insulin and thyroxine arrive at an organ at the same time. Thyroxine causes an effect on the organ but insulin does not. Why? a. Insulin is lipid-soluble hormone and thyroxine is not. b. The target cells in the organ have up-regulated thyroxine. c. Thyroxine is a local hormone and Insulin is a circulating hormone. d. Thyroxin inhibits the action of insulin. e. The organ's cells have receptors for thyroxine but not for insulin.

e. The organ's cells have receptors for thyroxine but not for insulin.

augments fight or flight response

epinephrine and norepinephrine

initiates development of ovarian follicles and stimulates follicular cells to secrete estrogen stimulates sperm production in the testes Release of this hormone is stimulated by GnRH

follicle-stimulating hormone

increases blood glucose level

glucagen (and hGH, epinephrine/norepinephrine, cortisol)

What causes hepatocytes to convert glycogen to glucose (glycogenolysis)?

glucagon; its release is stimulated by hypoglycemia and its release is inhibited by hyperglycemia

Tropins/ Tropic hormones

hormones that influence another gland

Main function is to promote synthesis of IGFs, stimulates protein synthesis, inhibits protein breakdown, stimulates lipolysis and retards use of glucose for ATP production

human growth hormone, hGH

stimulates and inhibits secretion of anterior pituitary hormones

hypothalamic regulating hormones

What is the major integrating link between the nervous and endocrine systems, acts as an endocrine gland itself, and helps control the stress response?

hypothalamus

decreases blood glucose level

insulin

Down-regulation makes a target cell _______ sensitive to a hormone while up-regulation makes a target cell ________ sensitive to a hormone.

less, more

Hormones are bound to transport proteins. The receptors are located inside the target cells. Includes: steroid hormones, thyroid hormones, nitric oxide

lipid soluble hormones

stimulates sex hormone production (release of estrogen and testosterone); triggers ovulation

luteinizing hormone

increases skin pigmentation when present in excess

melanocyte-stimulating hormone

regulates the body's biological clock

melatonin

enhances uterine contractions during labor; stimulates milk ejection

oxytocin

act on neighboring cells.

paracrines

increases blood Ca2+ level

parathormone

-Embedded into the posterior surface of the lateral lobes of the thyroid gland. -Has superior and inferior glands. -Two kinds of epithelial cells: Chief (principal) cells - produce parathyroid hormone (PTH) or parathormone. Oxyphil cell - function unknown.

parathyroid glands

-Regulates levels of calcium, magnesium, and phosphate ions in the blood. -Increases the activity and # of osteoclasts. -Stimulates the kidneys to synthesize calcitrol (active form of vitamin D). Calcitrol stimulates increased absorption of Ca2+ from the GI tract.

parathyroid hormone

-A small endocrine gland attached to the roof of the third ventrical of the brain. -Secretes melatonin, which is released in darkness and contributes to the body's biological clock.

pineal gland

-Synthesizes at least 7 different hormones. -Release of anterior pituitary hormones is stimulated by releasing hormones and suppressed by inhibiting hormones from the hypothalamus. -Attaches to the hypothalamus by a stalk, the infundibulum (= a funnel)

pituitary gland (hypophysis)

Does not synthesize any hormones; however, it does store and release two hormones from the hypothalamus: Oxytocin (OT). Antidiuretic hormone (ADH) a.k.a. vasopressin.

posterior pituitary

Initiates and maintains milk secretion by the mammary glands. Has a weak effect by itself, as the help of estrogens, progesterone, glucocorticoids, hGH, thyroxine and insulin this hormone brings about milk.

prolactin

local hormones involved in inflammation, smooth muscle contraction, and blood flow

prostaglandins

overproduction of melatonin during winter months. Full spectrum bright-light therapy can assist with this disorder and jet lag.

seasonal affective disorder

the sum of the actions of the 2 hormones is greater than either hormone individually. ex. Estrogens and FSH promote development of oocytes.

syngergistic effect

How are conditions like amenorrhea (absence of menstrual cycles), galactorrhea (inappropriate lactation), and erectile dysfunction in males caused?

the hypersecretion of prolactin

promotes T cell maturation

thymosin

-Located inferior to the larynx (voice box). -Right and left lateral lobes connected by an isthmus. -Anterior to the trachea. -Highly vascular. -Consists of thyroid follicles (spherical sacs). -The walls of each follicle contain follicular cells, which extend into the lumen of the follicle.

thyroid gland

stimulates synthesis of T3 and T4

thyroid-stimulating hormone

regulates oxygen use, basal metabolic rate, cellular metabolism and growth and development

thyroxine (T4) and triiodothyronine (T3)