Ch. 17 - Endocrine System Flashcards
Secretion
• controlled release of chemicals from a cell
4 classes of chemical messengers
1) Autocrine
2) Paracrine
3) Neurotransmitter
4) Endocrine
Paracrine
- produced by a wide variety of tissues and secreted into extracellular fluid; has a localized effect on other tissues
- secreted by one cell type into extracellular fluid and effect surrounding cells
Examples of Paracrine
- somatostatin
- histamine
- eicosanoids
Autocrine
• secreted by cells in a local area; influences the activity of the same cell from which it was secreted
Examples of Autocrine
- eicosanoids (prostaglandins, thromboxanes, prostacyclins, leukotrienes)
- good examples are those secreted by white blood cells during an infection
Neurotransmitter
- produced by neurons
- secreted into a synaptic cleft by presynaptic nerve terminals;
- travels short distances;
- influences postsynaptic cells
Examples of neurotransmitters
- acetylcholine
* epinephrine
Endocrine
• secreted into the blood by specialized cells; travels some distance to target tissues; results in coordinated regulation of cell function
Examples of endocrine
- thyroid hormones
- growth hormone
- insulin
- epinephrine
- estrogen
- progesterone
- testosterone
- prostaglandins
4 principle mechanisms of communication
1) gap junctions
2) neurotransmitter
3) Paracrine (local) hormone
4) hormones
Endocrine system
• glands, tissues, and cells that secrete hormones
Endocrinology
• The study of this system and the diagnosis and treatment of its disorders
Endocrine glands
• organs that are traditional sources of hormones
Hormones
• Chemical messengers that are transported by the bloodstream and stimulate physiological responses in cells or another tissue or organ, often a considerable distance away
_______ hormones bind to nuclear receptors, usually found in nucleus; _______ hormones bind to membrane-bound receptors
lipid-soluble; water-soluble
Chemical messengers
• allows cells to communicate with each other to regulate body activities
Secretions travel through ducts
• exocrine system
Secretions travel in bloodstream
• endocrine system
The tendency for one hormone to bind to only one type of receptor is called
•specificity
An increase in follicle-stimulating hormone causing an increase in luteinizing hormone receptors in ovary cells is an example of
• up-regulation
The process of one hormone activating multiple proteins, each which activates many enzymes, which produce an enormous amount of the final product
Amplification
Does the endocrine or nervous system have longer lasting effects?
• endocrine
Water-soluble hormones
- polar molecules
* include: protein hormones, peptide hormones, and most amino acid derivative hormones
Lipid-soluble hormones
- non polar
* include: steroid hormones, thyroid hormones, and fatty acid derivative hormones, such as certain eicosanoids
Transport of lipid-soluble hormones
• because of their small size and low solubility in aqueous fluids, lipid soluble hormones travel in the bloodstream bound to binding proteins
Transport of water-soluble hormones
• because water soluble hormones can dissolve in blood, many circulate as free hormones, meaning that most of them dissolve directly into the blood and are delivered to their target tissue without binding to a binding protein
Acute hormone secretion
- occurs when the hormones concentration changes dramatically and irregularly and it’s circulating levels differ with each stimulus
- levels can rapidly fluctuate in the blood
- example ➡️ epinephrine
Chronic hormone secretion
- relatively stable levels are maintained over a long period of time
- example ➡️ thyroid hormone
Episodic hormone secretion
- fluctuates on a regular cycle
* example ➡️ reproductive hormones regulating menstruation
Blood-borne molecules directly stimulate the release of hormones
Humoral stimuli
Neurons release a neurotransmitter into a synapse that influences the hormone producing cells
Neural stimuli
A hormone stimulates the secretion of another hormone
Hormonal stimuli
ANP is released by the atria to lower blood pressure
humoral stimuli
Hormones from the hypothalamus can prevent the release of hormones from the pituitary gland
neural stimuli
thyroid hormones control their own blood levels by inhibiting their pituitary tropic hormone
hormonal stimuli
Negative feedback
- most hormones secretions are regulated by this
- whereby a hormones secretions are regulated by the hormone itself
- example ➡️ thyroid hormones inhibit the secretion of TRH from the hypothalamus and TSH from the anterior pituitary
- self limiting system
Positive feedback
- occurs when a hormone is stimulated by a tropic hormone to secrete more of their own hormone as well as the tropic hormone
- example ➡️ prolonged estrogen stimulation promotes a release of luteinizing hormone
- self propagating system
Which ovarian hormone is involved in a positive feedback loop with the hypothalamus and the anterior pituitary?
• estrogen
Which hormone is released by the anterior pituitary as a part of that positive feedback loop between it and the ovary?
• Luteinizing hormone
Which hormone is released by the corpus luteum after ovulation and causes a negative feedback loop with the hypothalamus in the anterior pituitary?
• progesterone
Which hormone is released by the hypothalamus as a part of that positive feedback loop between it and the ovary?
• gonadotropin-releasing hormone (GnRH)
A process in which the body senses a change, and activates mechanisms to reverse that change
Negative feedback
Causes a self amplifying cycle where is a physiological change leads to an even greater change in the same direction
Positive feedback
Steroid hormones bind to
• protein receptors in the cytoplasm or nucleus of the target cell
What is the mode of action of steroid hormones?
- stimulation of mRNA transcription at that site
* which then codes for the synthesis of specific proteins
Are steroid hormones water soluble?
- no
* they are lipid-soluble and need a carrier protein to travel in the blood
What characteristic must a signal molecule have in order to bind with the intracellular receptor?
- it must be able to pass through the cellular membrane
* They are generally Nonpolar and fat-soluble
What do lipid soluble hormones do once inside the cell?
• bind with a specific receptor molecules inside the cytoplasm
What structure is formed after a lipid soluble hormone binds to a receptor molecule in the cytoplasm?
• A hormone-receptor complex is formed
What occurs after the hormone receptor complex is formed in the cytoplasm?
- The hormone-receptor complex moves into the nucleus and binds to DNA
- this stimulates synthesis of mRNA, which codes for a specific proteins
What happens once mRNA is synthesized?
- mRNA moves from nucleus into cytoplasm and binds to ribosomes where it directs the synthesis of specific proteins
- The proteins produce response of cell to the hormone
What is the ultimate result of lipid soluble hormones on cells?
• The production of proteins
3 classes of hormones:
1) amino acid derivatives
2) peptide hormones
3) lipid derivatives or steroid hormones
Hormones that use the cAMP second messenger system (non steroid hormones):
- ACTH
- calcitonin
- epinephrine
- glucagon
- parathyroid hormone
- ADH
The _____ senses high osmolarity in the plasma.
- kidney
* 1st step
________ neurons bring the information of high osmolarity to the hypothalamus.
- sensory
* 2nd step
The supra optic nucleus of the __________ fires impulses in response to the high osmolarity.
- hypothalamus
* 3rd step
The impulses from the hypothalamus travel through the _______ in the hypothalamo-hypophyseal tract.
- infundibulum
* 4th step
Exocytosis of ADH from the synaptic endings in the ______ pituitary.
- posterior
* 5th and final step
Where is dehydration detected?
• by osmoreceptors in the hypothalamus
Antidiuretic hormone (ADH) is released by the
• posterior pituitary
Where is ADH transported to?
• from posterior pituitary through blood stream to kidneys and blood vessels
ADH functions to
- reduce urine volume output, thereby increasing water retention and countering dehydration
- increase vasoconstriction in blood vessels, leading to higher blood pressure and thus countering the blood pressure drop caused by dehydration
After eating a meal, blood sugar levels
• increase
Insulin, released after a meal is eaten by a person who does not have diabetes, will cause blood sugar levels to
• return to about normal
In type I diabetes blood sugar levels remain high after a meal because
• no insulin is released
In type II diabetes blood sugar levels remain high after a meal because
- insulin is release but cells do not receive the signal
* muscle and liver cells do not receive signal
The treatment for Type I diabetes always includes
• insulin
The treatments for Type II diabetes are
- oral thiazolidinedione - increases cell sensitivity to normal insulin
- metformin - effective treatment for obese patients, an oral medication that blocks liver synthesis of glucose
What is the function of insulin?
• allows cells to take up glucose from the blood
The ______ secretes a hormone that increases the body’s metabolic rate, promotes alertness and quickens reflexes, and stimulates the fetal nervous system
• thyroid gland
The _____ secretes ____, which promotes Na + and water retention.
• adrenal cortex; aldosterone
The zona fasciculata in the adrenal gland secretes
• cortisol
Parathyroid hormone is released when blood calcium levels decrease. This is an example of control by _____ stimuli.
• humoral
Produces an increase in the sensitivity of the target cell to the hormone
• up-regulation
Steroid hormones:
a) bind to membrane receptors
b) diffuse easily through the plasma membrane
c) act by activating cAMP
d) are inactived by phosphodiesterase
e) are water soluble
b) diffuse easily through the plasma membrane
Many hours after a meal, alpha cells in the pancreatic islets (islets of Langerhans) secrete
• glucagon, which raised blood glucose
_____ is not a steroid hormone.
a) insulin
b) cortisol
c) progesterone
d) aldosterone
e) estradiol
a) insulin
Absence of iodine in the diet leads to
• hypothyroidism
T4 and T3 are _____ hormones that are mainly transported _____ in the blood.
• monoamine; bound to thyroxine-binding globulin (TBG)
Eicosanoids are derived from
• arachidonic acid
Prostaglandins have all the following roles except:
a) to induce labor contractions
b) to stop fever and pain
c) to constrict or dilate arterioles
d) to act as vasodilators or vasoconstrictors
e) to inhibit gastric secretions
b) to stop fever and pain
Aspirin and ibuprofen block
• the action of cyclooxygenase
All these can cause Cushing syndrome except:
a) ACTH hypersecretion by the pituitary
b) ACTH-secreting tumors
c) hyperactivity of the adrenal cortex
d) hyperactive of the adrenal medulla
e) excess cortisol secretion
d) hyperactivity of the adrenal medulla
Growth hormones (GH) hypersecretion causes gigantism when it begins in childhood, but it is more likely to cause _____ when it begins in adulthood.
• acromegaly
Diabetes mellitus is characterized by:
- NOT hypoglycemia
- polyuria
- polyphagia
- polydipsia
- glycosuria
These statements about diabetes mellitus are correct except:
- the body produces autoantibodies that destroy the pancreatic beta cells in type I DM
- target cells are unresponsive to insulin in type II DM
- both type I and type II DM are characterized by lack of, or low levels of, insulin - false
- diabetic neuropathy is a common long term effect of DM
- type II DM is more common than type I DM
Jerry drinks a few beers and soon has to urinate. The alcohol has
• inhibited secretion if ADH
Diabetes insipidus is caused by
• ADH deficiency
Oxytocin is administered to women following childbirth to stimulate
• uterine contractions
ADH and oxytocin are secreted by
• neurosecretory cells
One of the hallmarks of Graves’ disease is
• goiter
Simple goiter is most prevalent where the soil lacks
• iodine
Cretinism results from
• a deficiency of thyroid hormones at birth
Aldosterone promotes the homeostasis of ions by causing the kidneys to
• conserve sodium and excrete potassium
Hormones from the adrenal medulla increase
- blood pressure
- heart rate
- breathing rate
- force of cardiac muscle contraction
Cortisol is useful in controlling inflammation reactions because it
• decreases permeability of capillaries
Addison’s disease
- is caused by hyposecretion of cortical hormones
- decreases blood sodium levels
- increases blood potassium levels
- lowers blood pressure
The hormone that the pineal gland secretes is
• melatonin
The thymus gland secretes hormones called ____ that _____.
• thymosins; control production and differentiation of WBCs
Athletes abuse erythropoietin (EPO) because this hormone
• increases the number of RBCs
The anterior pituitary synthesizes hormones in response to hormones secretes by ______.
- hypothalamus
- NOT posterior pituitary
- The posterior pituitary does not synthesize any hormones, but only releases the ones delivered to it from the hypothalamus
What is true about endocrine system:
a) it communicates using neurotransmitters
b) it communicates using hormones secreted into the bloodstream
c) it causes metabolic activity changes in target cells
d) it typically has localized, specific effects in the body
e) it’s effects last from minutes to weeks
f) it’s effects may continue after the stimulus is removed
B, C, E, F
Which 2 hormones are produced by hypothalamus and transported to posterior pituitary?
- antidiuretic hormone (ADH)
* oxytocin (OT)
The _______ is the master control of the autonomic nervous system.
• hypothalamus
Hypothalamus hormones
- TRH
- GnRH
- GHRH
- CRH
Liver/fat, muscle, bone hormones
- GH
* IGF
Mammary gland hormones
• PRL
Thyroid hormones
• TSH
Testies/ovary hormones
- LH
* FSH
Adrenal cortex
• ACTH
Sequence of neurally controlled mechanism:
1) hypothalamus is in control
2) the master gland (hypothalamus) relays message to anterior pituitary gland
3) peripheral endocrine gland actually released the hormone
4) receptors (on target cells) receive the signal
5) changes occur (action)
Sequence of humorally controlled mechanism:
1) sensation of chemicals in the blood - changing level of substance in plasma
2) hormone release - endocrine gland
3) receptors receive the signal - target cells
4) changes occur - action
Neurosecretory cells
• neurons of the hypothalamus that control the anterior pituitary
Posterior neurosecretory cells
• neurons that release OT and ADH
Major control areas for ANS and endocrine system functions
• hypothalamus
Blood supply to posterior pituitary
• inferior hypophyseal artery
Saddle of sphenoid bone
• sella turcica
Neural portion of pituitary gland
• posterior lobe of pituitary gland
Veins leaving the pituitary gland
• hypophyseal veins
Glandular portion of pituitary
• anterior lobe of pituitary gland
Smallest blood vessels in hypophyseal portal system
• first capillary bed
Blood supply to the anterior pituitary
• superior hypophyseal artery
Neurons of the hypothalamus that control the anterior pituitary
• neurosecretory cells
Cross over of optic nerve
• Optic chiasma
Veins within pituitary stalk
• hypophyseal portal vein
Cells that release hormones
• Secretory cells
An up-regulated cell has an increase in:
• The number of receptors available for binding
Tropic hormones
• Stimulate certain endocrine glands to secrete hormones; produced by anterior pituitary gland
Which hormones are secreted by the anterior pituitary?
FLAT PiG • FSH • LH • ACTH (adrenocorticotropic hormone) • TSH (thyroid-stimulating hormone) • PRL (prolactin) • GH
The hypothalamo-hypophyseal portal system connects the hypothalamus to the..
• anterior pituitary or adenohypophysis
Function of posterior pituitary
• stores ADH and oxytocin in nerve terminals until they are stimulated by axons to be released into blood
3 layers of suprarenal cortex
1) zona glomerulosa
2) zona fasciculata
3) zona reticularis
Zona glomerulosa
- thin outer layer
- cells synthesize mineralcorticoids, a group of hormones that help regulate electrolyte composition and concentration in body fluids
- The principal mineralocorticoid is aldosterone, which helps regulate sodium and potassium ions in the blood and body fluids
Zona fasciculata
- thick middle layer of the cortex
- is composed of lipid rich cells that secrete glucocorticoids - these hormones stimulate metabolism of lipids and proteins, help regulate glucose levels in the blood, and play a role in decreasing inflammation
- The most common glucocorticoids are cortisol and corticosterone
Zona reticularis
- deepest layer of the cortex
- it’s cells are arranged in irregular chords and produce adrenal sex hormones, including weak androgens and small amounts of estrogens
Suprarenal medulla
- the inner core of each suprarenal gland; consists of large clusters of chromaffin cells
- when stimulated by sympathetic neurons of the autonomic nervous system, the medulla secretes the hormone epinephrine and norepinephrine
Cortisol is useful in controlling inflammation reactions because it
• decreases the permeability of capillaries
Cushing syndrome
- is caused by hypersecretion of corticol hormones
- elevates blood glucose
- elevates sodium concentrations
- decreases tissue protein
Type one diabetes mellitus is caused by
• A disorder in the immune system
Type two diabetes mellitus results from
• insensitivity of cells to insulin
Treatment of type two diabetes usually includes
- restricting dietary carbs to those high in fiber
- exercising regularly
- maintaining desirable bodyweight
- drugs
Parathyroid hormone stimulates the activity of bone resorbing osteoblasts
• false
Calicitonin is produced by the ______ gland
Thyroid
The hypothalamus secretes ______, which are classified as ________ hormones, whereby they increase the secretion of an anterior pituitary hormone, or ________ hormones, whereby they decrease the secretion of an anterior pituitary hormone.
• neurohormones, releasing, inhibiting
Hormones secreted by the hypothalamus travel through the hypothalamohypophysial portal system from the _______ to the _______.
• hypothalamus; anterior pituitary
Hypothalamic neuropeptides are carried from the hypothalamus to the posterior pituitary via a portal system.
• false?
Axons of the neurosecretory neurons extend from the hypothalamus through the infundibulum.
• true?
The axon endings of hypothalamic neurons store neurohormones in the posterior pituitary.
• true?
Neruohormones secreted by the posterior pituitary are produced by the hypothalamus.
• true?
The pituitary gland is located _________ to the hypothalamus and is connected to it by the ________.
• inferior; infundibulum
Stimulates the release of growth hormone
• growth hormone-releasing hormone
Decreases the release of growth hormone
• growth hormone-inhibiting hormone
Stimulates secretion of thyroid stimulating hormone
• thyrotropin-releasing hormone
Stimulates secretion of adrenocorticotropic hormone
• corticotropin-releasing hormone
Stimulates luteinizing and follicle-stimulating hormone
• gonadotropin-releasing hormone
Decreases the secretion of prolactin
• prolactin-inhibiting hormone
Stimulates the secretion of prolactin
• prolactin-releasing hormone
Increased growth in tissues
• growth hormone
Thyroid hormone secretion
• thyroid stimulating hormone
Glucocorticoid hormone secretion
• adrenocorticotropic hormone
Melanin production
• melanocyte stimulating hormone
Fat breakdown
• lipotropins
Follicle maturation and estrogen secretion
• follicle-stimulating hormone
Milk production in lactating woman
• prolactin
Analgesia in the brain
• beta endorphins
Ovulation and progesterone production
• Luteinizing hormone
Tropic hormones stimulate the secretion of other hormones from target tissues.
• true
Tropic hormones are secreted by the anterior pituitary gland.
• true
Tropic hormones are secreted by the posterior pituitary gland
• false
Tropic hormones can control the growth of target tissues
• true
Why aren’t hormones secreted from the anterior pituitary gland not neurohormones?
• because the anterior pituitary is derived from epithelial tissue of the embryonic oral cavity, not from neural tissue
Hypersecretion of growth hormone can lead to a condition called _______, while hyposecretion can lead to a disorder called ________.
• gigantism; pituitary dwarfism
The thyroid gland is located ________ to the larynx and is composed of two lobes connected by a narrow band of tissue called the _______.
• inferior; isthmus
Thyroid stimulating hormone stimulates T3 and T4 synthesis and secretion.
• true
T3 and T4 are secreted by thyroid follicles.
• true
T3 and T4 are secreted by the parafollicular cells.
• false
T3 and T4 are stored in the thyroid follicles as part of thyroglobulin.
• true
Most circulating T3 and T4 travel in the blood bound to ________.
• thyroxine binding globulin
Elevated levels of T3 and T4 ________ metabolic rate, while decreased levels of T3 and T4 _______ metabolic rate.
• increase; decrease
TRH and TSH function together to decrease the production of T3 and T4.
• false
TRH stimulates the secretion of TSH from the anterior pituitary.
• true
TSH stimulates the secretion of T3 and T4 from the thyroid gland.
• true
Increased blood levels of T3 and T4 inhibit TRH and TSH secretion.
- true
* a type of negative feedback
Hypothyroidism effects
- decreased metabolism
- Weight gain
- reduced appetite
- reduce heart rate
- constipation
Hypothyroid example cause
• iodine deficiency
Hyperthyroidism effects
- increased metabolic rate
- Weight loss
- increased appetite
- rapid heart rate
- diarrhea
- insomnia
- almost always a goiter
Hyperthyroidism cause
• Graves disease
Increased calcitonin levels result in ________ osteoclast activity in the bones, and________ you lifespan of osteoblasts, resulting in ________ blood calcium levels.
• decreased, lengthens, decreased
Parathyroid glands are composed of chief cells and oxyphils.
• true
Parathyroid glands are embedded in the lobes of the thyroid gland.
- true
* they are embedded in the posterior part of each lobe of the thyroid gland
Parathyroid glands secrete thyroid hormones.
- false
* The chief cells secrete parathyroid hormone, but the function of the oxyphils is unknown
Parathyroid glands secrete PTH.
• true
Parathyroid glands are organized in follicles.
- false
- usually, four parathyroid glands are present, with their cells organized and densely packed masted’s, or cords, rather than in follicles.
Hypoparathyroidism cause
• accidental removal during thyroidectomy
Hypoparathyroidism symptom
- hypoglycemia
* increase neuromuscular excitability
Hyperparathyroidism cause
• adenoma of the parathyroid gland
Hyperparathyroidism symptoms
- hyperglycemia
* weakened bones
The adrenal glands are located at the superior pole of each kidney.
• true
The adrenal glands are composed of an outer medulla and an inner cortex.
- false
* inner medulla outer cortex
The adrenal medulla arises from neural crest cells.
• true
The adrenal cortex is derived from mesoderm.
• true
Which is not a function of epinephrine or norepinephrine?
a) prepare the body for fight or flight
b) decrease blood glucose levels
c) increase heart rate
d) vasoconstriction of blood vessels in the viscera and skin
b) decrease blood glucose levels
Zona glomerulosa secretion type
• mineralocorticoids
Zona glomerulosa predominant hormone
• aldosterone
Zona fasciculata secretion type
• glucocorticoids
Zona fasiculata predominant hormone
• cortisol
Zona reticularis secretion type
• gonadocorticoids
• androstenedione
????
➡️ got this answer wrong on quiz
Zona reticularis predominant hormone
• androgens
?????
➡️ got this answer wrong on quiz
Aldosterone effect
•Increased sodium reabsorption in the kidneys
Cortisol effect
• increases blood glucose levels; suppresses the immune system
Androgens effect
• stimulate pubic and axillary hair growth and sex drive in females
Mineralocorticoid hyposecretion effect
• Low blood sodium levels, high blood potassium levels
Mineralocorticoid hypersecretion effects
• increased blood sodium levels, low blood potassium
Glucocorticoid hyposecretion effects
• Low blood glucose levels
Glucocorticoid hypersecretion effect
• hyperglycemia, depressed immune system
Androgen hyposecretion effect
• reduction of pubic and axillary hair in women
Androgen hypersecretion effect
• excess facial and body hair in women
Pancreatic islet beta cells hormone
• insulin
Pancreatic islet alpha cells hormone
• glucagon
Hyperglycemia (high blood glucose levels) would cause the pancreas to _______ insulin secretion, and hypoglycemia (low blood glucose levels) would cause the pancreas to _______ insulin secretion.
• increase; decrease
