Module 09: Endocrine System Flashcards
This system is composed of endocrine glands and specialized endocrine cells located throughout the body.
Endocrine System
Endocrine glands and cells secrete very small amounts of chemical messengers called ____________into the extracellular fluid. These diffuse into the blood to be transported to their target. They also circulate through the bloodstream to specific sites called target tissues or effectors. At their target tissues, they stimulate a specific response.
Hormones
These are the specific sites in the bloodstream where the hormones circulate and stimulate their specific response.
Target Tissues
Where is the term endocrine derived from?
derived from the Greek words endo, meaning “within,” and krino, “to secrete”-appropriately describes this system.
What makes exocrine glands different from endocrine glands?
Exocrine glands have ducts that carry their secretions to the out- side of the body, or into a hollow organ, such as the stomach or intestines. Examples of exocrine secretions are saliva, sweat, breast milk, and digestive enzymes.
This is where coordination to maintain the body’s homeostasis occurs. These allow cells to communicate with each other to regulate body activities.
Chemical Messengers
What are the four (4) chemical messengers in the endocrine system?
(1) Autocrine chemical messengers
(2) Paracrine chemical messengers
(3) Neurotransmitters
(4) Endocrine chemical messengers
This chemical messenger stimulates the cell that originally secreted it. Good examples of these chemical messengers are those secreted by white blood cells during an infection that have the capacity to replicate.
Autocrine chemical messengers
These chemical messengers are secreted by cells in a local area, which influences the activity of the same cell or cell type from which it was secreted.
Autocrine chemical messengers
What are some examples of Autocrine chemical messengers?
(1) Eicosanoids (prostaglandins, thromboxane, prostacyclin, and leukotrienes)
These chemical messengers act locally on neighboring cells. These chemical messengers are secreted by one cell type into the extracellular fluid and affect surrounding cells.
Paracrine chemical messengers
These chemical messengers are produced by a wide variety of tissues and secreted into extracellular fluid; has a localized effect on other tissues
Paracrine chemical messengers
What are some examples of Paracrine chemical messengers?
Somatostatin, histamine, eicosanoids
These stimulates vasodilation in nearby blood vessels.
Histamine
These chemical messengers are secreted by neurons that activate an adjacent cell, whether it is another neuron, a muscle cell, or a glandular cell. These are secreted into a synaptic cleft, rather than into the bloodstream
Neurotransmitters (neurotransmitters are paracrine chemical messengers)
These chemical messengers are produced by neurons; secreted into a synaptic cleft by presynaptic nerve terminals; travels short distances; influences postsynaptic cells
Neurotransmitters
What are some examples of neurotransmitters?
Acetylcholine, epinephrine
These chemical messengers are secreted into the bloodstream by certain glands and cells, which together constitute the endocrine system. These chemical messengers travel through the blood to their target cells.bo
Endocrine chemical messengers
These chemical messengers are secreted into the blood by specialized cells; travels some distance to target tissues; results in coordinated regulation of cell function
Endocrine chemical messengers
What are some examples of Endocrine chemical messengers?
Thyroid hormones, growth hormone, insulin, epinephrine, estrogen, progesterone, testosterone, prostaglandins
What is the function of hormones’?
Hormones of the endocrine system are secreted in response to humoral, neural, or hormonal stimuli to regulate homeostasis.
What are the main regulatory functions of the endocrine system?
(1) Regulation of metabolism.
(2) Control of food intake and digestion.
(3) Modulation of tissue development
(4) Regulation of ion levels.
(5) Control of water balance
(6) Regulation of cardiovascular functions.
(7) Control of blood glucose and other nutrients.
(8) Control of reproductive functions.
(9) Stimulation of uterine contractions and milk release.
(10) Modulation of immune system function.
This function of the endocrine system pertains to the act of controlling the rate of nutrient utilization and energy production.
Regulation of metabolism.
This function of the endocrine system pertains to the act of regulating the level of satiation (fullness) and the breakdown of food into individual nutrients.
Control of food intake and digestion.
This function of the endocrine system pertains to the act of influencing the development of tissues, such as those of the nervous system
Modulation of tissue development
This function of the endocrine system pertains to the act of helping to monitor blood pH, as well as Na, K, and Ca2+ concentrations in the blood.
Regulation of ion levels.
This function of the endocrine system pertains to the act of regulating water balance by controlling the solute concentration of the blood as well as controlling membrane
Control of water balance
This function of the endocrine system pertains to the act of helping to regulate the heart rate and blood pressure and prepare the body for physical activity.
Regulation of cardiovascular functions.
This function of the endocrine system pertains to the act of regulating the levels of glucose and other nutrients in the blood.
Control of blood glucose and other nutrients.
This function of the endocrine system pertains to the act of controlling the development and functions of the reproductive systems in males and females.
Control of reproductive functions
This function of the endocrine system pertains to the act of regulating uterine contractions during delivery and stimulates milk release from the breasts in lactating females
Stimulation of uterine contractions and milk release
This function of the endocrine system pertains to the act of helping the control the production of immune cells.
. Modulation of immune system function.
What are the two chemical categories of hormones?
(1) lipid-soluble hormones and
(2) water-soluble hormones
What is the basis of hormone metabolism?
its transport in the blood, its interaction with its target, and its removal from the body
These hormones are derived from cholesterol.
Steroid hormones
These hormones’ are derived from amino acid tyrosine,
thyroid hormones (other hormones are categorized as amino acid derivatives, peptides, or proteins.)
This chemical category of hormones are nonpolar, and include steroid hormones, thyroid hormones, and fatty acid derivative hormones, such as certain eicosanoids.
Lipid-soluble hormones (can last for several days to weeks)
What are the three mechanism that could potentially result in the removal of lipid-soluble hormones from the body?
Lipid-soluble hormones’ are unprotected and may not effectively regulate.
(1) breakdown by enzymes in the liver or enzymes in the lungs.
(2) excretion into urine by the kidneys or bile from the liver, and
(3) breakdown by enzymes in the bloodstream.
Lipid soluble hormones are bounded in these. These are the “chaperone” the hormone. And helps in reducing the rate at which lipid-soluble hormones are degraded or removed from the blood.
Binding proteins
This chemical category of hormones are polar molecules; they include protein hormones, peptide hormones, and most amino acid derivative hormones.
Water-soluble hormones
How are water soluble transported?
(1) Most of them dissolve directly into the blood and are delivered to their target tissue without attaching to a binding protein
(2) Due to their size, they do not readily diffuse through the walls of all capillaries; therefore, they tend to diffuse from the blood into tissue spaces more slowly
These limit the length of time they are active, and body processes change quickly when hormones are secreted and remain functional for only short periods.
destruction and elimination of hormones
How long do water soluble hormones last?
have relatively short half-lives because they are rapidly broken down by enzymes within the bloodstream but they have concentrations that change rapidly within the blood and tend to regulate activities that have a rapid onset and short duration.
What are the three (3) modifications made to hormone molecules that help protect them from being destroyed?
- Having a carbohydrate attached to them.
- Having a terminal end protected from protease activity,
- Having binding proteins
These hormones circulate in the plasma longer than free water-soluble hormones do.
Bound Hormones
What are the three (3) types of stimuli regulate hormone release
(1) humoral,
(2) neural, and
(3) hormonal
In this, the blood level of most hormones fluctuates.
homeostatic range
Molecules and ions in the bloodstream can directly stimulate the release of some hormones. These chemicals are referred to as __________________. The cells that secrete these hormones have receptors for certain substances in the blood.
humoral stimuli.
This word pertains to body fluids, including blood
humoral
Examples:
(1) hormone (PTH) is released in response to the chemical’s concentration.
(2) elevated blood glucose levels directly stimulating the pancreas to secrete the hormone insulin,
(3) elevated blood potassium levels directly stimulating the adrenal cortex to secrete the hormone aldosterone.
This hormone regulation involves neural stimuli of endocrine glands. In this, following action potentials, neurons release a neurotransmitter into the synapse with the cells that produce the hormone In some cases, the neurotransmitter stimulates the cells to increase hormone secretion.
Neural stimuli
Give an example of neural stimuli.
For example, the sympathetic nervous system stimulates the secretion of epinephrine and norepinephrine, from the adrenal gland during exercise. Epinephrine and nor- epinephrine increase heart rate and, in turn, increase blood flow through the exercising muscles.
Some neurons secrete chemical messengers directly into the blood when they are stimulated, making these chemical messengers hormones, which are called _______________. They stimulate the secretion of releasing hormones.
neuropeptides
Specialized neuropeptides stimulate hormone secretion from other endocrine cells and are called _______________ a term usually reserved for hormones from the hypothalamus and travel in the blood to the anterior pituitary gland.
releasing hormones, (stimulating hormones)
This type of hormonal regulation occurs when a hormone is secreted that, in turn, stimulates the secretion of other hormones.
Hormonal Stimuli
These are hormones in the hypothalamus and anterior pituitary land that stimulate the secretion of another hormone.
Tropic hormones
What regulates the releasing hormones, (stimulating hormones)?
Hormonal Stimuli
What do the releasing hormones stimulate?
Releasing hormones stimulate the release of hormones from the anterior pituitary that travel in the blood to their target endocrine cell. The target endocrine cell secretes its hormone into the blood, where it travels to its target and produces a response.
How does the humoral stimuli inhibits hormone release?
In this the companion hormone’s effects oppose those of the secreted hormone and counteract its effect or action.
How does the neural stimuli inhibits hormone release?
Neurons inhibit targets just as often as they stimulate targets. If the neurotransmitter is inhibitory, the target endocrine gland does not secrete its hormone.
How does the hormonal stimuli inhibits hormone release?
hormones prevent the secretion of other hormones, which is a common mode of hormone regulation.
These hormones from the hypothalamus prevent the secretion of tropic hormones from the anterior pituitary gland.
Inhibiting hormones.
What are the two major mechanisms maintain hormone levels in the blood within a homeostatic range?
(1) negative feedback and
(2) positive feedback
In this mechanism, the hormone’s secretion is inhibited by the hormone itself once blood levels have reached a certain point and there is adequate hormone to activate the target cell.
Negative Feedback Mechanism
Why is the Negative Feedback Mechanism known as the self-limiting system?
Because the hormone may inhibit the action of other, stimulatory hormones to prevent the secretion of the hormone in question
How does the thyroid hormones inhibit the secretion of their releasing hormone?
(1) The anterior pituitary gland secretes a tropic hormone, which travels in the blood to the target endocrine cell.
(2) The hormone from the target endocrine cell travels to its target.
(3) The hormone from the target endocrine cell also has a negative- feedback effect on the anterior pituitary and hypothalamus, which decreases secretion of the tropic hormone.
This mechanism promote the synthesis and secretion of the tropic hormone in addition to stimulating their target cell. In turn, this stimulates further secretion of the original hormone.
Positive Feedback Mechanism
The Positive Feedback Mechanism is also known as what?
Self-Propagating System
Cite an example of a positive feedback mechanism.
prolonged estrogen stimulation promotes a release of the anterior pituitary hormone responsible for stimulating ovulation.
This bodily system consists of ductless glands that secrete hormones into the interstitial fluid The hormones then enter the blood.
Endocrine system
It is a small gland about the size of a pea. It is housed in a depression of the sphenoid bone inferior to the hypothalamus of the brain.
Pituitary Gland
This serves as a control center for the autonomic nervous system as well as the endocrine system lies superior to the pituitary gland. It is a region of the diencephalon, located inferior to the thalamus.
Hypothalamus
The pituitary gland lies posterior to the optic chiasm and is connected to the hypothalamus by a stalk called the ____________.
infundibulum
The pituitary gland can be divided into two parts, namely:
(1) Anterior Pituitary Gland
(2) Posterior Pituitary Gland
This part of the pituitary gland is made up of epithelial cells derived from the embryonic oral cavity.
Anterior Pituitary Gland
This part of the pituitary gland is n extension of the brain and is composed of neurons.
Posterior Pituitary Gland
Why was the pituitary gland known as the master gland?
Hormones from the pituitary gland control the functions of many other glands in the body, such as the ovaries, the testes, the thyroid gland, and the adrenal cortex.
How does the hypothalamus control the pituitary gland?
(1) hormonal control and
(2) direct innervation.
Explain the hypothalamic control of the anterior pituitary gland
(!) Neurons of the hypothalamus produce neuropeptides and secrete them into a capillary bed in the hypothalamus. Stimuli within the nervous system regulate the secretion of releasing hormones and inhibiting hormones (circles) from neurons of the hypothalamus.
(2) Releasing hormones and inhibiting hormones pass through the hypothalamohypophysial portal system to the anterior pituitary.
(3) Once the neuropeptides arrive at the anterior pituitary gland, they leave the blood and bind to membrane-bound receptors involved with regulating anterior pituitary hormone secretion. The capillary beds and veins that transport the releasing and inhibiting hormones are called the hypothalamic-pituitary portal system. The hypothalamic neuropeptides function as either releasing hormones or inhibiting hormones. Each releasing hormone stimulates the production and secretion of a specific hormone by the anterior pituitary. Each inhibiting hormone reduces the production and secretion of a specific hormone by the anterior pituitary.
(4) In response to releasing hormones, anterior pituitary hormones (squares) travel in the blood to their target tissue, which in some cases, are other endocrine glands.
The capillary beds and veins that transport the releasing and inhibiting hormones are called the ________________________.
hypothalamic-pituitary portal system
Explain the hypothalamic control of the posterior pituitary gland
(1) Stimulation of neurons within the hypothalamus controls the secretion of the posterior pituitary hormones.
(2) Action potentials are conducted by axons of the hypothalamic neurons through the hypothalamohypophysial tract to the posterior pituitary. The axon endings of neurons store hormones in the posterior pituitary.
(3) In the posterior pituitary gland, action potentials cause the release of hormones (circles) from axon terminals into the circulatory system.
(4) The hormones pass through the circulatory system and influence the activity of their target tissues.
The hormones secreted from the anterior pituitary are _____________. They are transported in the blood, have a life span measured in minutes, and bind to membrane-bound receptors on their target cells.
Proteins
This hormone in the anterior pituitary gland stimulates the growth of bones, muscles, and other organs by increasing gene expression. It also slows protein breakdown (protein synthesis) during periods of food deprivation and favors lipid breakdown (for energy metabolism) and release in the cells. It also encourages the increase in blood glucose levels
Growth Hormone
How does the GH increase blood glucose levels?
By reducing glucose utilization (insulin antagonist)
Too little growth hormone secretion can result from abnormal development of the pituitary gland. A young person suffering from a deficiency of growth hormone remains small, although normally proportioned, and is called a _________________.
pituitary dwarf (dwarf)
How can GH be administered?
The gene in the bacteria causes GH synthesis, and the GH can be extracted from the medium in which the bacteria are grown.
What is the target tissue of the GH?
Most Tissues
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. As a result, the facial features and hands become abnormally large, a condition called _______________.
acromegaly
What are the two (2) hormones that controls the secretion of growth hormone?
(1) A releasing hormone stimulates growth hormone secretion, and
(2) an inhibiting hormone inhibits its secretion.
Part of the effect of growth hormone is influenced by a group of protein hormones called _______________.
insulin-like growth factors (IGFs), or somatomedins
What is the relationship of GH and the insulin-like growth factors (IGFs), or somatomedins?
Growth hormone increases IGF secretion from 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. The IGFs are similar in structure to insulin and can bind, to some degree, to insulin receptors. Also, insulin, at high concentrations, can bind to IGF receptors.
This hormone in the anterior pituitary gland binds to membrane-bound receptors on cells of the thyroid gland and stimulates the secretion of thyroid hormone. This can also stimulate growth of the thyroid gland.
Thyroid-stimulating hormone (TSH)
This triggers the pituitary gland to release Thyroid-stimulating hormone (TSH).
Thyrotropin releasing hormone
How is the rate of TSH regulated?
The rate of TSH secretion is regulated by a releasing hormone from the hypothalamus
What is the target tissues of the Thyroid-stimulating hormone (TSH)?
Thyroid Gland
This hormone is secreted by the Thyroid-stimulating hormone (TSH) which denotes the active thyroid hormone
triiodothyronine (T3)
This hormone is secreted by the Thyroid-stimulating hormone (TSH) which denotes the the precursor of the thyroid hormone produced by the thyroid gland.
thyroxine (T4)
What happens when there is too much or too less of Thyroid-stimulating hormone (TSH)?
TSH can also stimulate growth of the thyroid gland. Thus, when too much TSH is secreted, the thyroid gland enlarges and secretes too much thyroid hormone. When too little TSH is secreted, the thyroid gland decreases in size and secretes too little thyroid hormone.
What is the target tissue of the Adrenocorticotropic hormone (ACTH)?
Adrenal cortex
This hormone in the anterior pituitary gland binds to membrane-bound receptors on cells of the adrenal cortex. This also increases the secretion of a hormone from the adrenal cortex called cortisol (glucocorticoid). This is also required to keep the adrenal cortex from degenerating. The molecules also bind to melanocytes in the skin and increase skin pigmentation at high concentrations
Adrenocorticotropic hormone (ACTH)
How is too much Adrenocorticotropic hormone (ACTH) manifested?
One symptom of too much ACTH secretion is darkening of the skin. The rate of ACTH secretion is increased by a releasing hormone from the hypothalamus.
The Adrenocorticotropic hormone (ACTH increases the secretion of a hormone from the adrenal cortex called ____________.
cortisol also called hydrocortisone.
These hormones from the anterior pituitary gland bind to membrane- bound receptors on the cells of the gonads (ovaries and testes). These regulate the growth, development, and functions of the gonads.
gonadotropins
What are the different types of gonadotropins?
(1) Luteinizing Hormone or interstitial cell-stimulating hormone
(2) Follicle-stimulating Hormone
In females, what does the luteinizing hormone do?
In females, LH stimulates ovulation. LH also promotes the secretion of the reproductive hormones, estrogen and progesterone, from the ovaries.
In males, what does the luteinizing hormone do?
In males, LH stimulates interstitial cells of the testes to secrete the reproductive hormone testosterone and sperm cells production in testis
In females and males, what does the follicle-stimulating hormone do?
FSH stimulates the development of follicles in the ovaries (follicle maturation), estrogen secretion in the ovary and sperm cells in the testes.
What is the target tissue of the Luteinizing Hormone or interstitial cell-stimulating hormone?
Ovary in females and testis in males
What is the target tissue of the follicle-stimulating hormone?
Follicles in ovary in females and seminiferous tubules in males
What happens when there is no LH or FSH?
Without LH and FSH, the ovaries and testes decrease in size, no longer produce oocytes or sperm cells, and no longer secrete hormones.
This hormone in the anterior pituitary gland 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. It also prolongs progesterone secretion following ovulation and pregnancy and increase sensitivity to LH in males
Prolactin (mammotropic hormone or lactotropic hormone)
What is the principal control that inhibits the secretion of prolactin from the hypothalamus?
Prolactin Inhibiting Hormone (Dopamine)
What is the target tissue of prolactin?
Ovary and mammary gland in females and testis in males
What hormone stimulates the secretion of prolactin from the hypothalamus?
Prolactin Releasing Hormone
This hormone in the anterior pituitary gland binds to membrane-bound receptors on melanocytes and causes them to synthesize melanin. The structure of this is similar to that of ACTH, and oversecretion of either hormone causes the skin to darken.
Melanocyte-stimulating hormone
How is the Melanocyte-stimulating hormone regulated?
there appear to be two regulatory hormones from the hypothalamus-one that increases MSH secretion and one that decreases it.
What is the target tissues of Melanocyte-stimulating hormone?
Melanocytes in the skin
This hormone binds to membrane-bound receptors and increases water reabsorption by kidney tubules. This results in less water lost as urine. This can also cause blood vessels to constrict when released in large amounts and decreases sweating
Antidiuretic hormone (ADH) - anti, against +uresis, urine volume
What happens when there is a lack of secretion of Antidiuretic hormone (ADH)
A lack of ADH secretion causes diabetes insipidus, which is the production of a large amount of dilute urine. The large urine volume is created by excess water loss from the blood, which increases the concentration of the body fluids and causes the loss of important electrolytes, such as Ca+, Na+, and K+ (dehydration)
What is the target tissue of the Antidiuretic hormone (ADH)?
Kidneys
The Antidiuretic hormone (ADH) can also be called ___________.
Vasopressin
This is in the arterioles can raise or maintain blood pressure.
Vasoconstriction
This hormone in the pituitary gland 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
Oxytocin
How is oxytocin stimulated?
Nerve impulses from the hypothalamus as cervix is stretched and as infants suck the nipple
What is the target tissues of the oxytocin?
Uterus and mammary gland
What are Pitocin?
These are commercial forms of oxytocin that are given under certain conditions to assist in childbirth and to constrict uterine blood vessels.
This is one of the largest glands in the endocrine system which synthesizes and secretes three hormones: (1) triiodothyronine (T,), (2) thyroxine (tetraiodothyronine; T), and (3) calcitonin. It appears more red than the surrounding tissues because it is highly vascular. It is surrounded by a connective tissue capsule.
Thyroid Gland
The thyroid gland is made up of two lobes connected by a narrow band called the ___________
Isthmus
Where are the lobes of thyroid gland located
The lobes are located on each side of the trachea, just inferior to the larynx
These are small spheres with walls composed of simple cuboidal epithelium in the thyroid gland.
thyroid follicles (The epithelial cells of the follicles synthesize the thyroid hormones, T, and T,, which are stored with- in the follicles.)
Each thyroid follicle is filled with the _______________ to which thyroid hormones are attached and secreted
protein thyroglobulin (Thyroid hormones attach to nuclear receptors in their target cells and regulate the metabolic rate of the body
Where is calcitonin secreted?
Between the follicles is a network of loose connective tissue that contains capillaries and scattered parafollicular cells, or C cells, which secrete the hormone calcitonin.
This is required to synthesize thyroid hormones.
Iodine
This contains four iodine atoms
Thyroxine or tetraiodothyronine (T4)
These hormones regulate metabolic rates and is needed for growth and maturation. They also regulate protein, carbohydrate, and fat metabolism. This is also necessary for normal physical, mental, and sexual development.
Thyroid Hormones
What are the target tissues of the thyroid hormones?
Most cells of the body
This contains four iodine atoms.
Thyroxine or tetraiodothyronine (T4)
This contains three iodine atoms.
Triiodothyronine (T3)
How is the thyroid hormone secreted?
(1) The hypothalamus secretes TSH-releasing hormone, also known as TRH Stress and hypothermie cause TRH to be released from neurons within the hypothalamus. It passes through the hypothalamity pophysal portal system to the anterior pituitary
(2) TRH travels to the anterior pituitary to stimulate the secretion of thyroid-stimulating hormone (TSH)
(3) TSH causes increased synthesis and release of T, and T, into the general circulation. 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 thyroid hormones from thyroglobulin. Decreasing blood levels of TSH decrease the synthesis and release of thyroid hormones.
(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
What happens when there is a negative feedback effect of thyroid hormones on the hypothalamus and pituitary?
results in increasing levels of thyroid hormones inhibiting the secretion of TSH-releasing hormone from the hypothalamus and inhibiting TSH secretion from the anterior pituitary gland.
However, decreasing thyroid hormone levels allow additional TSH-releasing hormone and TSH to be secreted.
What happens when there is an absence of negative feedback?
a loss of negative feedback will result in excess TSH. This causes the thyroid gland to enlarge, a condition called a goiter.
this condition occurs 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.
Goiter
This condition pertains to the ack of thyroid hormones. This condition can result in low body temperature, weight gain, reduced appetite, and lethargy, among other symptoms.
hypothyroidism
This condition is characterized by developmental delay, short stature, and abnormally formed skeletal structures
Cretinism
This condition pertains to an elevated rate of thyroid hormone secretion. This can result in increased metabolic rate, extreme nervousness, and chronic fatigue.
Hyperthyroidism
This diseases =is an autoimmune disease that causes hyperthyroidism. This disease occurs when the immune system produces abnormal proteins that see similar and function to TSH, which overstimulates the thyroid gland.
Grave’s diseases
What happens when a patient is diagnosed with grave’s disease?
In people with Graves disease, the in system produces a large amount of a protein that is so much like TSH that binds to cells of the thyroid gland and acts like TSH Unlike TSH, however, the secretion of this protein does not respond
to negative feedback
This hormone is secreted by parafollicular cells of the thyroid glands. This is secreted when Ca+ becomes too high in the blood concentration. This lowers blood Cal levels to return to their normal range. It also lowers phosphate and help maintain stable bone matrix
Calcitonin
Graves disease is often accompanied by bulging of the eyes, a condition called
exophthalmia
How does calcitonin lowers blood Cal levels to return to their normal range?
Calcitonin binds to membrane- bound receptors of osteoclasts and inhibits them. Inhibition of osteoclasts reduces the rate of Ca reabsorption (breakdown) from bone
What are the target tissues of Calcitonin?
Primarily Bone
This hormone is secreted by the parathyroid gland which is essential for maintaining and regulating f blood calcium levels
Parathyroid Hormone (PTH)
How many parathyroid glands are embedded in the posterior wall of the thyroid gland?
four
What are the importance of the Parathyroid Hormone (PTH)?
(1) PTH increases active vitamin D formation through effects on membrane-bound receptors of renal tubule cells in the kidneys. Vitamin D stimulates increased Ca” absorption by intestinal epithelial cells.
(2) PTH secretion increases blood Ca” levels. PTH binds to receptors on osteoblasts. In turn, osteoblasts secrete substances that stimulate osteoclasts to reabsorb bone.
(3) PTH decreases loss of Ca in the urine.
(4) Increases rate of bone breakdown by osteoclasts due to increased reabsorption that can lead to bone density
Explain the synthesis of Vitamin D
Vitamin D is produced from precursors in the skin that are modified by the liver and kidneys. Ultraviolet light acting on the skin is required for the first stage of vitamin D synthesis, and the final stage of synthesis in the kidney is stimulated by PTH.
What are the target tissues of the Parathyroid Hormone (PTH)
Bone and Kidney
What happens when Ca2+ is low?
Osteoclasts breakdown (inhibit) bone breakdown and less Ca+ is lost in the urine
This condition pertains to an abnormally high rate of PTH secretion. One cause of this is a tumor in a parathyroid gland. The elevated blood levels of PTH increase bone reabsorption, which elevates blood Ca2+ levels.
Hyperparathyroidism
What happens when a patient is diagnosed with hyperparathyroidism?
As a result, bones can become soft, deformed, and easily fractured. In addition, the elevated blood Ca2+ levels make nerve and muscle cells less excitable, resulting in fatigue and muscle weakness. The excess Ca2+ can be deposited in soft tissues of the body, causing inflammation. In addition, kidney stones can result.
This condition pertains to the abnormally low rate of PTH secretion. This can result from injury to or the surgical removal of the thyroid and parathyroid glands. The low blood levels of PTH lead to reductions in the rate of bone reabsorption and the formation of vitamin D.
Hypoparathyroidism
What happens when a patient is diagnosed with Hypoparathyroidism?
As a result, blood Ca2+ levels decrease. 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 tetanus can affect the respiratory muscles; breathing stops, resulting in death.
These are glands are two small glands located superior to each kidney. They contain the adrenal medulla (inner part) and adrenal cortex (outer part)
Adrenal Glands
This is known as the inner part of the adrenal gland.
Adrenal Medulla
This is known as the outer part of the adrenal gland.
Adrenal Cortex
What hormones does the adrenal medulla contain?
(1) Epinephrine
(2) Norepinephrine
This is also known as the adrenaline and accounts for 80% of the adrenal medulla secretions.
Epinephrine
This hormone secreted by the adrenal medulla accounts for 20% of its secretions.
Norepinephrine
How does the adrenal medulla secretes its hormones?
(1) An increased frequency of action potentials conducted through the sympathetic division of the autonomic nervous system stimulates the adrenal medulla to secrete epinephrine and some norepinephrine into the circulatory system.
(2) These hormones bind to membrane-bound receptors in their target tissues, where they prepare the body for intense physical activity.
Epinephrine and Norepinephrine are called what hormones?
Fight or Flight Hormones because they prepare the body for intense physical activity along with the sympathetic division function
What are the effects of Epinephrine and Norepinephrine?
(1) Release of stored energy sources to support increased physical activity. For example, glucose derived from breakdown of liver glycogen and fatty acids derived from the breakdown of adipose tissue.
(2) Increased blood pressure. Two effects of epinephrine cause an elevated blood pressure.
a. Increased heart rate.
b. Constriction of blood vessels in skin and internal organs.
(3) Increased blood flow to skeletal muscle. The
vasoconstriction in the internal organs and skin blood vessels reduces blood flow to those tissues. The smooth muscle in skeletal muscle blood vessels does not contract. That, in combination with decreased blood flow elsewhere, explains the increased blood flow to the skeletal muscle.
(4) Increased metabolic rate of several tissues, especially skeletal muscle, cardiac muscle, and nervous tissue.
What are the target tissues of epinephrine and norepinephrine?
Heart, blood vessels, liver, adipocytes
This gland secretes three classes of steroid hormones: (1) mineralocorticoids (2) glucocorticoids and (3) adrenal androgens. The molecules of all three classes of steroid hormones enter their target cells and bind to nuclear receptor molecules.
Adrenal cortex
These regulate ion balance in the blood. They are also the major secretory products of the zona glomerulosa of the adrenal cortex.
Mineralocorticoids
This is produced by greatest amounts and secreted under low blood pressure conditions. It returns blood pressure to its normal range through modulation of kidney function. This also increases the rate of Na reabsorption by the kidneys, which increases blood levels of Nat. The higher blood Na levels enhance water reabsorption through osmosis thereby increasing blood pressure.
Aldosterone
How does Aldosterone stimulate K excretion?
This reabsorption of water increases blood volume and thereby increases blood pressure. Aldosterone also stimulates K excretion into the urine by the kidneys, which lowers blood levels of K+. In addition, aldosterone increases the rate of H+ excretion into the urine.
What happens when too much aldosterone is secreted?
When aldosterone is secreted in high concentrations, reduced blood K+ levels and alkalosis (elevated pH of body fluids) may result.
What is the target tissues of the aldosterone
Heart, blood vessels, liver, adipocytes
This help to provide energy for cells by stimulating the increased use of lipids and proteins. It is the middle layer of the adrenal cortex that secretes hormones, primarily cortisol. They also cause lipid breakdown, reduce glucose and amino acid uptake in skeletal muscle, stimulate synthesis of new glucose from precursor molecules, such as amino acid, and increase protein degradation. They can also also increase blood glucose levels and glycogen deposits in cells. The glucose and glycogen are a reservoir of molecules that can be metabolized rapidly.
Glucocorticoids
The responses of glucocorticoids can be classified as what?
The responses are classified as metabolic, developmental, or anti-inflammatory.
How are glucocorticoids decrease immune response?
Glucocorticoids decrease the intensity of the inflammatory and immune responses by decreasing both the number of white blood cells and the secretion of inflammatory chemicals from tissues
These are often used to suppress the immune response in people suffering from autoimmune conditions and in transplant recipients.
Synthetic glucocorticoids
This is important under conditions of stress, when the rate of glucocorticoid secretion is relatively high.
anti- inflammatory effect of cortisol
This is released from hypothalamic neurons in response to stress or low blood glucose, and passes, by way of the hypothalamohypophysial portal system, to the anterior pituitary.
Corticotropin-releasing hormone (CRH)
How is cortisol regulated?
(1) In the anterior pituitary, CRH binds to and stimulates calls that secrete adrenocorticotropic hormone (ACTH)
(2) The middle layer of the adrenal cortex is very sensitive to ACTH Once ACTH binds to its membrane-bound receptors, the adrenal
cortex increases cortisol secretion
(3) Cortisol acts on target tissues, resulting in increased breakdown of lipids and proteins, higher glucose levels, and increased and inflammatory effects.
(4) Both ACTH and cortisol act via negative feedback to inhibit CR secretion from the hypothalamus.
What happens when there is high concentrations of cortisol?
High concentrations of cortisol in the blood inhibit ACTH secretion from the anterior pituitary and low concentrations timulate it.
This is the third class of hormones secreted by the inner layer of the adrenal cortex. This is composed of the adrenal androgens, which stimulate the development of male secondary sex characteristics.
Androgens
Where are androgens secreted in adult females?
In adult females, the adrenal androgens influence the female sex drive, growth of pubic, and axillary hair
Where are androgens secreted in adult males?
In adult males, most androgens are secreted by the testes.
What happens when androgens are secreted abnormally high?
If the secretion of reproductive hormones from the adrenal cortex is abnormally high, exaggerated male characteristics develop in both males and females.
What are the target tissues of the mineralocorticoids or aldosterone?
Kidneys; to lesser degree, intestine and sweat glands
What are the target tissues of the glucocorticoids (cortisol)?
Most tissues (liver, fat, skeletal muscle, immune tissues)
What are the target tissues of the adrenal androgens?
Most tissues
This consists of pancreatic islets (islets of Langerhans), which are dispersed throughout the exocrine portion of it.
Pancreas
These are part of the endocrine portion of the pancreas, which are dispersed throughout its exocrine portion.
Pancreatic Islets (islets of Langerhans)
What are the three (3) cell types that form the islet?
(1) Alpha cells
(2) Beta cells
(3) Delta cells
This portion of the pancreas secretes digestive enzymes.
Exocrine Portion
These cells in the islets secrete glucagon.
Alpha cells
These cells in the islet secrete insulin.
Beta cells
These cells in the islet secrete somatostatin.
Delta cells
Why are the cells in the pancreatic islet important?
It is very important to maintain blood glucose levels within a normal range (blood level nutrients) . 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___________, which are released into the blood.
acidic ketones
This condition occurs when blood glucose levels are very low, the breakdown of lipids can cause the release of enough fatty acids and ketones to reduce the pH of the body fluids below normal.
Acidosis
This is secreted when there are elevated blood glucose levels from the break down and utilization of the amino acids by the liver. It can also be stimulated when there is an increase in blood levels and parasympathetic stimulation associated with digestion of a meal.
Insulin (binds to membrane-bound receptors and, either directly or indirectly, increases the rate of glucose and amino acid uptake in these tissues to form glycogen)
What are two signals that inhibit insulin secretion?
(1) low blood glucose levels and
(2) stimulation of the sympathetic nervous system.
What happens when there is a decrease in insulin?
blood glucose to be conserved to provide the brain with adequate glucose and to allow other tissues to metabolize fatty acids and glycogen stored in the cells.
This is the area of the hypothalamus that controls appetite, called the _____________.
Satiety center
What is the target tissue of insulin?
Liver, skeletal muscle, adipose tissue
This is converted to glycogen or lipids, and the amino acids are used to synthesize protein.
Glucose
This is the body’s inability to regulate blood glucose levels within the normal range. This condition is caused by too little insulin or faulty insulin receptors.
Diabetes mellitus
This diabetes mellitus occurs when too little insulin is secreted from the pancreas. This is when the patient insulin dependent.
Type 1
This diabetes mellitus is caused by either too few insulin receptors on target cells or defective receptors on target cells. The defective receptors do not respond normally to insulin (diet).
Type 2
What happens during hyperglycemia?
Because glucose cannot enter the cells of the satiety center in the brain without insulin, the satiety center responds as if there were very little blood glucose, resulting in an exaggerated appetite. The excess glucose 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 thirsty. E
This condition occurs when tissues cannot take up glucose effectively, causing blood glucose levels to become very high.
Hyperglycemia
This occurs when the brain, which depends primarily on glucose for an energy source, malfunctions and causes disorientation and convulsions and may result in loss of consciousness.
Insulin Shock
This pancreatic hormone is released from the alpha cells when blood glucose levels are low. This also binds to membrane- bound receptors primarily in the liver, causing the glycogen stored in the liver to be converted to glucose.
Glucagon
What are the target tissues of glucose?
Primarily the Liver
What is the function of glucagon?
Between meals glucose levels drop and glucagon is secreted. It allows glycogen to be broken down into glucose
This pancreatic hormone is released by the delta cells in response to food intake. This inhibits the secretion of insulin and glucagon and inhibits gastric tract activity
Somatostatin
What happens to insulin and glucagon when blood glucose increases and decreases?
When blood glucose levels decrease, the rate of insulin secretion declines, and the rate of glucagon secretion increase (vice versa)
This is known as the main reproductive hormone in the male, which is secreted by the testes. It regulates the production of sperm cells by the testes and the development and maintenance of male reproductive organs and secondary sexual characteristics and promotes the closure of epiphysis of long bones along with sexual behavior
Testosterone
What are two main classes of reproductive hormones secreted by the ovaries?
(1) Estrogen
(2) Progesterone
What are the functions of estrogen and progesterone
These hormones, along with the anterior pituitary hormones control the female reproductive cycle (menstrual cycle), prepare the uterine and mammary glands for lactation, and maintain pregnancy. They are also responsible for the the female reproductive organs and female secondary sexual characteristics.
These hormones stimulate the secretion of estrogen and progesterone
Luteinizing and Follicle Stimulating Hormone
What are the target tissues of the testosterone along with the estrogen and progesterone?
Most tissues
This structure of the endocrine system lies in the upper part of the thoracic cavity. It is important in the function of the immune system.
Thymus
This hormone is secreted by the thymus which aids the development of white blood cells called T cells that help protect the body against infection by foreign organisms.
Thymosin
Why is the thymosin important in infants?
The thymus is most important early in 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 are the target tissues of thymosin?
Immune tissues
This gland is a small, pinecone- shaped structure located superior and posterior to the thalamus of the brain and secretes the hormone melatonin and is known to control the onset of puberty.
Pineal glands
What hormones does melatonin inhibit>
reproductive hypothalamic-releasing hormone (which produces LH and FSH) gonadotropin-releasing hormone
What is the difference of short day length and longer day length in terms of melatonin secretion?
short day length causes an increase in melatonin secretion, whereas longer day length causes a decrease in melatonin secretion.
What is the target tissues of melatonin?
Hypothalamus
These hormones function mainly as autocrine or paracrine chemical signals. Others cause relaxation of smooth muscle, such as dilation of blood vessels. They also play a role in inflammation. They are released by damaged tissues and cause blood vessel dilation, localized swelling, and pain.. Prostaglandins produced by platelets appear to be necessary for normal blood clotting.
Prostaglandins
How does Prostaglandins initiate abortion?
Others cause contraction of smooth muscle, such as contraction of the uterus during the delivery of a baby. Because of their action on the uterus, prostaglandins have been used. medically to initiate abortion
This is secreted by the right atrium in response to elevated blood pressure. This inhibits Na+ reabsorption in the kidneys. This causes more urine to be produced, reducing blood volume. Lowered blood volume lowers blood pressure
atrial natriuretic hormone
This is secreted by the kidneys in response to reduced oxygen levels in the blood. Erythropoietin acts on bone marrow to increase the production of red blood cells
erythropoietin
What hormones are secreted by the placenta to maintain pregnancy and stimulating milk production?
(1) Estrogen
(2) Progesterone
(3) gonadotropin
