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Definition
endocrine system messengers of the body that are produced and excreted by specific cells for the purpose of regulating specific organs or cells
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a group of cells that secrete regulatory substances directly into the bloodstream.
Produced by endocrine gland cells (or modified neurons) travel through the bloodstream to distant cell and tissues, where they produce their effects. |
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| The two body systems that help maintain homeostasis in the body are ____ |
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| The two body systems that help maintain homeostasis in the body are the endocrine system and nervous system |
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| the nervous system messengers |
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| a cell that has receptors for a particular hormone is referred to as a target of that hormone |
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| basic units of the endocrine system. Located throughout the body, they secrete tiny amts of hormones directly in the bloodstream. This method of secretion gives them the nickname ductless glands. This feature differentiates them from exocrine glands (exo = out) |
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| secrete their products onto epithelial surfaces through tiny tubes called ducts. |
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| hormonelike substances that are produced and exert many effects locally in a variety of body tissues. Sometimes called tissue hormones because they regulate biochemical activities in the tissues where they are formed. |
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| the master endocrine gland. A pea-sized endocrine gland located at the base of the brain; made up of the anteriorpituitary gland, which produces seven known hormones, and the posterior pituitary gland, which stores and releases two hormones from the hypohakamus; also called the hypophysis. |
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| (G2) the anterior pituitary hormone that promotes body growth in young animals and helps regulate the metabolism of proteins, carbohydrates, and lipids in all of the body’s cells |
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| thyroid-stimulating hormone, from the pituitary gland. Stimulates the thyroid gland to produce its hormone. When the level of thyroid hormone drops below certain levels, , the anterior pituitary produces more TSH, which stimulates the thyroid gland to produce more of its hormone |
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Parts of the endocrine system:
adrenal glands |
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Definition
The adrenal glands are critical to normal body functions, such as maintenance of fluid balance, reaction to stress, and reproduction. There are two adrenal glands, each of which lies above a kidney. The adrenal glands have two distinct parts: the cortex (outer layer), which secretes steroid hormones, and the medulla (inner part), which secretes epinephrine and norepinephrine.
There are more than 30 steroid hormones produced by the adrenal glands. These hormones serve to regulate a wide array of processes throughout the body. Epinephrine and norepinephrine are responsible for the changes in heart rate, blood pressure, and level of usable glucose (a form of sugar) that are necessary to cope with stress. |
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Parts of the endocrine system:
Pancreas |
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Definition
The pancreas is located in the rear center of the abdominal cavity, behind the stomach. Specialized cells in the pancreas produce two hormones, insulin and glucagon, needed to maintain stable blood sugar levels in the body. Insulin helps body cells use glucose for energy, thereby reducing the amount of sugar in the bloodstream. To balance this action, the hormone glucagon stimulates the liver to release its stored sugar into the blood, thereby raising the blood sugar levels.
The pancreas also functions in digestion. Nonendocrine cells in the pancreas produce special chemicals called enzymes, which are secreted directly into the small intestine through ducts. These enzymes help break down proteins, carbohydrates (sugars and starches), and fats in the small intestine. This dual activity of the pancreas means that it functions as both an endocrine and an exocrine organ. |
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Parts of the endocrine system:
Pituitary glands |
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Definition
The pituitary gland is a small organ located just beneath the base of the brain, between the two frontal lobes and directly above a cavity called the sphenoid sinus. It is sometimes called the master gland because all other endocrine glands come under its control. Its job is to receive messages about the need for a particular hormone and to secrete either the hormone or substances that cause the manufacture and release of the hormone.
The anterior (front) lobe of the pituitary gland secretes somatotropin (growth hormone), which affects the body's general growth; thyrotropic hormone (thyroid-stimulating hormone), which acts on the thyroid gland to stimulate production of thyroid hormones; adrenocorticotropic hormone (ACTH), which stimulates the adrenal cortex; follicle-stimulating hormone and luteinizing hormone, which are necessary for maturation and release of egg and sperm cells; and prolactin, a hormone that acts on the mammary glands to promote the secretion of milk.
The posterior lobe of the pituitary gland secretes oxytocin, which stimulates smooth muscle tissue to contract (and is of critical importance during childbirth) and vasopressin, a hormone that regulates by acting on the kidneys. |
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Parts of the endocrine system:
Sex glands |
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Definition
Sex Glands
The primary responsibility for hormone production for the reproductive system lies with the testes (male sex glands) and ovaries (female sex glands).
The testes are two oval organs in the scrotum (the pouch of skin behind the penis). The testes produce sperm and sex hormones that govern the male secondary sex characteristics, including the growth of facial hair.
The two ovaries are located in the pelvis. The ovaries secrete the hormones estrogen and progesterone, which govern ovulation (monthly release of an egg from an ovary) and the female secondary sex characteristics, such as breast development. |
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Parts of the endocrine system:
Thyroid and parathyroid |
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Definition
Thyroid and Parathyroid Glands
The thyroid gland is located at the front of the neck above the top of the breastbone. It consists of two main lobes on either side of the trachea (windpipe) that are connected by a narrow band of tissue called the isthmus. The hormones secreted by the thyroid influence the rate of metabolism (the chemical processes in the body having to do with energy production).
The four parathyroid glands are located on the back and side of each lobe of the thyroid gland. Their secretion, parathyroid hormone, controls calcium levels in the blood.
The endocrine system is one of the most important processes of the body. Understanding the system's components can help you understand how the human body works. |
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| Seven hormones of the anterior pituitary gland: |
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Definition
- growth hormone
- prolactin
- thyroid-stimulating hormone
- Adrenocorticotropic hormone
- Follicle-stimulating hormone
- Luteinizing hormone
- Melanocyte-stimulating hormone |
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| antidiuretic hormone – a hormone released by the posterior pituitary. It facilitates water conservation in the body by promoting water reabsorption from urine in the collecting ducts. Low levels of ADH cause diabetes insipidus, a condition that results in excessive water loss from the body through increased urine volume. |
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| – Follicle-stimulating hormone – named for its effect in the female. Stimulates the growth and development of follicles in the ovaries. Also stimulates the lining cells of the follicles to produce and secrete estrogens, the female sex hormones. In the male, FSH has an effect similar to its effects in the female. It stimulates spermatogenesis, the development of male reproductive cells, the spermatozoa, in the seminiferous tubules of the testes. |
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| Luteinizing hormone – completes the process of follicle development in the ovary that was started by FSH |
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| Compare and contrast the endocrine and nervous systems. |
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Definition
General Fxn:
ES: reg of body fxns to maintain homeostasis
NS: reg of body fxns to maintain homeostasis
Rxn to stimuli:
ES: Slow
NS: Fast
Duration of effects:
ES: Long
NS: Short
Target tissues:
ES: Virtually all body cells and tissues
NS: Muscle and glandular tissues
Chemical messenger:
ES: Hormone
NS: Neurotransmitter
Messenger producing cells:
ES: Endocrine gland cells or modified neurons
NS: Neurons
Distance from chemical msg production to target.:
ES: Long (via bloodstream)
NS: Short (Across synaptic space)
Both use chemicals to transmit msgs but do it by different means. |
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| 7) How do calcitonin and parathyroid hormone work together to regulate homeostasis of blood calcium concentration? Why is this important? |
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PTH (aka parathormone) helps maintain blood calcium homeostasis by exerting an effect opposite to calcium. PTH helps prevent hypocalcemia by inc the blood calcium level if it should fall. Does this thru effects on kidneys (causes to retain calcium), intestine (to absorb calcium from food), bones (the calcium “bank”).
Calcitonin helps prevent hypercalcemia by dec the blood cal level if too high. Does this mainly by encouraging the excess calcium to be deposited in the bones (the “calcium bank”. Calcitonin is a vital substance – many important body fxns like muscle contraction, blood clotting, milk secretion, and formation/maint of skeleton |
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| 6) What role does the thyroid gland play in regulation of the metabolic rate? |
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| Thyroid hormone’s calorigenic effect helps heat the body. It regulates the metabolic rate of all the body’s cell: the rate at which they burn nutrients to produce energy. Its influence over the metabolic rate of the body’s cells allows an animal to generate heat and maintain a constant internal body temp, while the temp of the outside temp changes. Production of thyroid hormone increases with exposure to cold temps. Response increases met rate, gens more heat – causes nutrients to be burned at faster rate. |
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| 5) What hormones are secreted and stored by the pituitary gland and what are the effects? (make sure and include the hormones secreted and stored in the anterior and posterior sections) |
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The rostral (front) portion is called the anterior pituitary. Develops from glandular tissue in an embryo and looks like normal glandular tissue under the microscope.
The seven known anterior pituitary hormones:
- growth hormone
- prolactin
- thyroid-stimulating hormone
- Adrenocorticotropic hormone
- Follicle-stimulating hormone
- Luteinizing hormone
- Melanocyte-stimulating hormone
Colville pg 362 – 364
The caudal (rear) portion os called the posterior pituitary, develops from the embryo’s nervous system and looks like nervous tissue under the scope. Does not produce any hormones, instead it serves as storage for 2 hormones produced in the hypothalamus to be stored for periodic release into the bloodstream. ADH and oxytocin are transported along nerve fibers down to the posterior pituitary and stored in nerve endings. Nerve impulses from the hypothalamus tell the nerve endings when to release them into the bloodstream.
2 hormones stored:
Anitdiuretic hormone (ADH
Oxytocin |
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| 4) What is the master gland? |
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Definition
| The pituitary gland is often called the master gland because many of its hormones direct the activity of other glands around the body. |
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| 3) How does a negative feedback system control hormone secretion of some hormones? |
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| When the level of a certain hormone drops to a certain amount, the production of the hormone is stimulated. When the level reaches the right amount the feed back has a negative effect, the production is turned down. |
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| 2) Describe the target cell concept. Why is this important to the function of the endocrine system? |
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| Each body cell has specific receptors to a variety of hormones. These receptors are like locks into which only specific keys (hormones) can fit. When a hormone (key) binds to its receptor (lock) in or on a cell, it changes some activity of that cell. If a cell does not have receptors to a particular hormone, that hormone just flows by without producing any effect on that cell. A cell that has receptors for a particular hormone is referred to as a target of that hormone |
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| 9) How do insulin and glucagons affect the concentration of glucose in the blood? |
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Insulin causes glucose, amino acids, and fatty acids in the bloodstream to be absorbed through cell memb into body cells and used for energy. Lowers the level of glucose in the blood.
Glucagon – opposite effect from insulin. Raises the blood glucose level by 2 mechanisms
1. stimulates liver cells to convert glycogen (a storage form of glucose) to glucose.
2. 2. stimulates gluconeogenesis (the conversion of fat and protein breakdown products to glucose)
Net effect of both is to raise the blood glucose level. Because other hormones, such as GH (from the anterior pituitary gland) and glucocorticoid hormones (from the adrenal cortex) have similar hyperglycemic effects, a deficiency of glucagons is not as devastating to the body as a deficiency of insulin |
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| 8) List the hormones of the adrenal glands and briefly describe their action/purpose. Why might some of these be considered essential for life? |
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Definition
The adrenal glands appear to be a single structure but are 2 glands, one wrapped around the other, the outer adrenal cortex and the inner adrenal medulla come from different embryological origins and have diff structures and fxns.
Adrenal cortex – outer gland, from and looks like glandular tissue microscopically. Under the direction of ACTH from the anterior pituitary gland and other mech, it produces 3 main groups of hormones
- glucocorticoid hormones – name comes from effect on blood glucose levels, they have a hyperglycemic effect. Other effects include helping to maintain BP and helping body resist the effects of stress.
include cortisone, cortisol, and corticosterone
- Mineralocorticoid hormones – reg the level of some important electrolytes (mineral salts) in the body. The principal min hormone, aldosterone, affects the levels of sodium, potassium, and hydrogen ions in the body. Also affects water levels in the body in that water accompanies sodium back into the bloodstream when sodium ions are reabsorbed.
- Sex hormones – produces small amts of sex hormones. Androgens (male s.h.), estrogens (female s.h). amts very small with minimal effects.
Adrenal medulla – inner gland, develops from and looks like nervous tissue microscopically. Produces epinephrine and norepinephrine. Under the control of the sympathetic portion of the autonomous nervous system. The threat control system |
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| 10) How might long term glucocorticoid therapy affect our patients? |
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Definition
Glucocorticoid side effects include:
- suppression of the immune response
- wbc count alteration
- slowing of wound healing
- catabolic effect – after long-term use the catabolism (breakdown) of protein can result in thinning of the skin, loss of hair and a general loss of muscle mass
- premature parturition
- hyperglycemia
- suppression of adrenal cortex stimulation – the feedback mech interpret the high levels of drug as high levels of glucorticoid hormones. Causes a cascade effect from the hypothalamus to the anterior pituitary gl;and to the adrenal cortex. Hypothalamus decreases its production of ACTH-releasing factor, which causes the anterior pituitary gland to decrease its production of ACTH, resulting in diminished stimulation of the adrenal cortex. Long-term, high level corticosteroid drug use actually can cause physical shrinkage (atrophy) of the adrenal cortex. If corticosteroid drug admin were then suddenly withdrawn, pt would have severe deficiency of glucocorticoid hormones, resulting in signs of hypoadrenocorticism (aka Addison’s dz). Therefore, long-term use of corticosteroid drugs should not be terminated suddenly but tapered off gradually to give the adrenal cortex a chance to recover.
- Iatrogenic hyperadrenocorticism – can result when excessive levels of corticosteroid drugs are administered; iatrogenic means caused by treatment. Signs mimic naturally occurring hyperadrenocorticism. |
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| 12) Why are prostaglandins referred to as tissue hormones? Prostaglandins are produced in which body tissues |
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Definition
Prostoglandins are hormonelike substances that are derived from unsaturated fatty acids. They are produced and exert their effects w/in a variety of body tissues.
-incl skin, intestine, brain, kidney, lungs, repro organs, and eyes
Because they only travel a short distance from where they are produced, prostoglandins are sometimes called tissue hormones. They only regulate the activites of neighboring cells. |
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