Biology Endocrine System Flashcards
___ glands synthesize and secrete chemical substances called hormones directly into the circulatory system
endocrine
In contrast, ___ glands, such as the gallbladder, secrete substances transported by ducts
exocrine
The hypothalamic hormones regulate pituitary gland secretions via a ___ feedback loop
negative
Releasing hormones are ___ into the hypophyseal portal system
secreted
In the hypophyseal portal system, blood from the capillary bed in the ___ flows through a portal vein into the anterior pituitary (hypophyseal portal system), where it diverges into a second capillary network
hypothalamus
Releasing hormones can immediately reach the anterior ___ without first entering the circulatory system
pituitary
In the hypothalamus, the vast majority of feedback regulation is negative feedback, in which the product of the ___ inhibits its own production
pathway
The pituitary gland hangs below the ___ and is connected to it by a slender cord known as the infundibulum
hypothalamus
The ___ contains both the hypophyseal portal system and the neurosecretory axons, connecting the hypothalamus to the posterior pituitary gland
infundibulum
The anterior pituitary synthesizes both direct hormones , which directly act on their target organs, and tropic ___, which stimulate other endocrine glands to release hormones
hormones
The hormonal secretions of the anterior pituitary are regulated by hypothalamic hormones called ___/inhibiting hormones or factors
releasing
(Tropic Hormones) Follicle stimulating hormone (FSH): In women FSH causes ___ of ovarian follicles which in turn secrete estrogen
maturation
(Tropic hormones) Luteinizing hormone (LH): In women LH stimulates ___ and maintenance of the corpus luteum
ovulation
(Tropic hormones) adrenocorticotropic hormone (ACTH): ACTH stimulates the adrenal cortex and secrete ___ and is regulated by corticotropin-releasing factor (CRF)
glucocorticoids
(tropic hormones) thyroid-stimulating hormone (TSH):TSH stimulates the ___ gland to synthesize and release thyroid hormones, thyroxine (T) and triiodothyronine (T3)
thyroid
(direct hormones) prolactin: ___ stimulates milk production in female mammary glands
prolactin
(direct hormones) endorphins: These are ___ that have pain-relieving properties
neurotransmitter
(direct hormones) growth hormone (GH, somatotropin): GH promotes bone and muscle growth. GH also promotes protein synthesis and lipid mobilization and ___
catabolism
(direct hormones) melanocyte-stimulating hormone (MSH): MSH is secreted by the intermediate lobe of the ___. In mammals, MSH plays a role in the sun-induced darkening of skin (tanning). When amphibians are in darker environments for long periods of time, mSH is released causing darkening of skin in order to better camouflage with the environment
pituitary
The ___ pituitary (neurohypophysis) does not synthesize hormones
posterior
Instead, the posterior pituitary releases the peptide hormones oxytocin and ___ hormone, which are produced by the ___ cells of the hypothalamus
peptide, neurosecretory
Oxytocin, which is secreted during childbirth, increases the strength and frequency of ___ muscle contractions
uterine
___ secretion is also induced by suckling; oxytocin stimulates milk secretion in the mammary glands
oxytocin
Antidiuretic hormone (ADH) increases water permeability in the ___ duct of the nephron, thereby promoting water reabsorption and increasing blood volume, which subsequently increases blood pressure and decreases blood osmolarity
collecting
ADH is ___ when plasma osmolarity increases, as sensed by osmoreceptors in the hypothalamus, or when blood volume decreases, as sensed by baroreceptors in the circulatory system
secreted
In response to stress, adrenocorticotropic hormone (ACTH), which is produced by the ___ pituitary, stimulates the adrenal cortex to produce more than two dozen different steroid hormones, collectively known as adrenocortical steroids or simply corticosteroids
anterior
___ exert their action by determining which genes are transcribed in the nuclei of their target cells and at what rate
corticosteroids
(corticosteroid) glucocorticoids, such as cortisol and cortisone, are involved in ___ regulation and protein metabolism
glucose
(corticosteroid) Glucocorticoids raise blood glucose levels by promoting protein breakdown and ___ and decreasing protein synthesis
gluconeogenesis
(corticosteroid) glucocorticoids are ___ to the effects of insulin and trigger the release of amino acids from skeletal muscle, as well as lipids from adipose tissue
antagonistic
(corticosteroid) ___ also promote the peripheral use of lipids and have anti-inflammatory effects
glucocorticoids
(corticosteroid) mineralocorticoids, particularly aldosterone, regulate ___ levels of sodium and potassium and, consequently, the total extracellular fluid volume
plasma
(corticosteroid) ___ causes active reabsorption of sodium and passive reabsorption of water in the nephron of the kidney
aldosterone
(corticosteroid) Active reabsorption of sodium and passive reabsorption of water results in an increase in both blood ___ and blood pressure
volume
(corticosteroid) The ___ are stimulated by angiotensin II and inhibited by ANP (atrial natriuretic peptide0
mineralocorticoid
(corticosteroid) The production of angiotensin II is regulated by the lungs and the ___, which are sensitive to blood pressure changes
kidney
(corticosteroid) ___ (male sex hormones) are secreted from the adrenal cortex in small quantities in both men and women
androgens
The adrenal medulla produces ___ (adrenaline) and norepinephrine (noradrenaline), both of which belong to a class of amino acid-derived compounds called catecholamines
epinephrine
___ increases the conversion of glycogen to glucose in liver and muscle tissue, causing an increase in blood glucose levels and an increase in the basal metabolic rate
epinephrine
Both epinephrine and norepinephrine increase the ___ and strength of the heartbeat and dilate and constrict blood vessels in such a way as to increase the blood supply to the skeletal muscles, heart, and brain, while decreasing the blood supply to the kidneys, sin, and digestive tract
rate
Both epinephrine and norepinephrine will also promote the release of lipids by ___ tissue
adipose
The ___ is controlled by thyroid-stimulating hormone (TSH) from the anterior pituitary, which is in turn stimulated by thyroid-releasing hormone (TRH) from the hypothalamus
thyroid
The thyroid is located in front of the ___ and has two major functions, the first being metabolism regulation (including growth for children) through the release of triiodothyronine (T3) and thyroxine (T4)
trachea
The second function of the thyroid is regulation of blood calcium levels through the release of ___, which has an antagonistic role with parathyroid hormone (produced in the parathyroid glands)
calcitonin
The thyroid hormones, thyroxine (T4) and triiodothyronine (T3), are formed from the ___ thyroglobulin, which is synthesized in thyroid cells
glycoprotein
(thyroid hormones) ___ is five times more potent than T4
T3
(thyroid hormones) T4 and T3 are transported via plasma proteins. Approximately 99.5% of these hormones are bound to proteins, but only an unbound hormone is able to enter a cell and elicit a ___ response
cellular
(thyroid hormones) All of the T4 in the body is formed and secreted by the ___ gland; however, only 20% of T3 is produced by the thyroid gland
thyroid
___ decreases plasma CA2+ concentration by inhibiting the release of Ca2+ from bone and promoting the storage of Ca2+ in bones
Calcitonin
Calcitonin secretion is regulated by plasma ___ levels
Ca2+
Calcitonin is ___ to parathyroid hormone
antagonistic
___ is not affected y the hypothalamus or the pituitary gland
calcitonin
Gonadotropin-releasing hormone (GnRH) from the ___ acts on the anterior pituitary to release the gonadotropins (LH and FSH)
hypothalamus
In men, both ___ and FSH act on the testes to produce testosterone and foster the maturation of sperm cells
Luteinizing hormone (LH)
In females, the gonadotropins cause the secretion of ___ and protesterone
estrogen
Gonadotropin-releasing hormone (GnRH) promotes the production of FSH and LH in the ___ pituitary which act on the gonads which then release testosterone or estrogen and progesterone
anterior
Corticotropin-releasing factor (CRF) promotes the production of ___ hormone (ACTH) in the anterior pituitary which act on the adrenal cortex which then release glucocorticoids (cortisol and cortisone)
adrenocorticotropic
Thyroid-releasing hormone promotes Thyroid-stimulating hormone (TSH) in the anterior ___ which acts on the thyroid which then release Triiodothyronine (T3) and Thyroxine (T4)
pituitary
Dopamine promotes the production of Prolactin in the anterior pituitary which act on the ___ tissue
breast
Growth hormone-releasing hormone (GHRH) promotes the production of growth hormone in the anterior pituitary which act on the ___ and muscle
bone
A decrease in ___ from the hypothalamus promotes prolactin secretion
dopamine
The parathyroid glands synthesize and secrete parathyroid hormone (PTH), which regulates ___ Ca2+ concentration
plasma
PTH raises the ___ concentration in the blood by stimulating Ca2+ release from the bone and decreasing Ca2+ excretion in the kidneys
Ca2+
Calcium in bone is bonded to ___, upon there being low Ca 2+ levels in the blood, and breakdown of the bone releases phosphate as well as calcium
phosphate
Parathyroid hormone ___ for breakdown of the bone by stimulating excretion of phosphate by the kidneys
compensates
The pancreas is both an ___ organ and an endocrine organ
exocrine
The exocrine function of the ___is performed by the cells that secrete digestive enzymes into the small intestine via a series of ducts
pancreas
The ___ function is performed by small glandular structures called the islets of Langerhans, which are composed of alpha and beta cells
endocrine
Alpha cells produce and secrete ___, while beta cells produce and secrete insulin
glucagon
The endocrine hormones of the ___ are regulated through negative feedback and are antagonistic to one another
pancreas
___, a peptide hormone, is released by the pancreas when blood glucose levels are low
glucagon
Upon release, glucagon stimulates ___ and fat degradation, the conversion of glycogen to glucose, and ___, all of which serve to increase blood glucose levels
gluconeogenesis
___, a protein hormone, is secreted in response to a high blood glucose concentration
Insulin
Insulin acts on ___ transporters on the cell membrane of liver, muscle, and adipose cells, resulting n the uptake of glucose
glucose
___ also stimulates the synthesis of fats form glucose and the uptake of amino acids
Insulin
The effects of insulin all serve to lower blood ___ levels
glucose
The ___ plays a crucial role in the renin-angiotensin-aldosterone (RAA) system, which heavily regulates both blood volume and blood pressure
kidney
When blood volume falls, the kidneys produce renin - an enzyme that converts the plasma protein ___ to angiotensin I
angiotensinogen
Angiotensin I (produced by the liver) is converted to angiotensin II in the ___, which stimulates the adrenal cortex to secrete aldosterone
kidney
___ helps restore blood volume by increasing sodium reabsorption by the kidneys, leading to an increase in fluid retention
aldosterone
The kidneys also produce ___
erythropoietin (EPO)
EPO is a glycoprotein that stimulates red blood cell ___; it is normally produced in the kidneys
production
___ is carried to the gastric glands and stimulates the glands to secrete HCl in response to food in the stomach
gastrin
The hormone ___ is released by the small intestine when acidic chyme enters from the stomach
secretin
Secretin stimulates the secretion of an alkaline bicarbonate solution from the ___ that neutralizes the acidity of the chyme
pancreas
The hormone ___ is released by the small intestine in response to the presence of fats and causes the contraction of the gallbladder and release of bile into the small intestine
cholecystokinin
Bile, which is not a hormone, is involved in the ___ and digestion of fats
emulsification
(Pineal gland) In primitive vertebrates, melatonin lightens the skin by concentrating pigment ___ in melanophores (melatonin is an antagonist to MSH)
granules
___: amino acid chains
peptides
Peptide hormones act as ___
first messengers
When ___ bind to specific receptors on the surface of their target cells, they trigger a series of enzymatic reactions within each cell, the first of which may be the conversion of ATP to cyclic adenosine monophosphate (cyclic AMP); this reaction is catalyzed by the membrane-bound enzyme adenylate cyclase
peptides
Cyclic AMP acts as a second messenger, relaying messages from the extracellular peptide hormone to ___ enzymes and initiating a series of reactions in the cell
cytoplasmic
Cyclic AMP acting as a second messenger is an example of a ___ effect; with each step, the hormone’s effects are multiplied
cascade
Cyclic AMP activity is inactivated by the cytoplasmic enzyme ___
phosphodiesterase
Because they are ___ soluble, steroid hormones cross the phospholipid bilayer and enter their target cells directly in order to bind to specific receptor proteins in the cytoplasm
lipid
Upon binding to specific receptors in the cytoplasm, this receptor-hormone complex enters the ___ and directly activates the expression of specific genes by binding to receptors on the chromatin
nucleus
___ mechanism of action involves binding to a receptor, inducing a conformational change, and regulating transcription at the level of the DNA
steroid
Peptide hormones are quick while steroid hormones are ___
slow
___ actions are short lived while steroid hormones are long-lived
peptide hormone
