ENDOCRINE SYSTEM Flashcards
is composed of endocrine glands and specialized endocrine cells located throughout the body
endocrine system
hormones circulate through the bloodstream to specific sites called
target tissues
allow cells to communicate with each other to regulate body activities
chemical messengers
what are the types of chemical messengers
autocrine chemical messengers
paracrine chemical messengers
neurotransmitters
endocrine chemical messengers
this type of chemical messenger stimulates the cell that originally secreted it . good examples are those secreted by white blood cells during an infection
autocrine chemical messengers
this type of chemical messenger act locally on neighboring cells ; secreted by one cell type into the extracellular fluid and affect surrounding cells. example is histamine
paracrine chemical messengers
this type of chemical messengers are secreted by neurons that activate an adjacent cell, whether neuron, muscle, or glandular cell ; secreted into the synaptic cleft rather than into the blood stream
neurotransmitters
this type of chemical messengers are secreted into the bloodstream by certain glands and cells ; travel through the blood to their target cells
endocrine chemical messengers
two categories of hormones
lipid soluble
water soluble
these type of hormones are nonpolar and include steroid, thyroid, and fatty acid derivative hormones
lipid soluble hormones
lipid soluble hormones travel into the bloodstream bound to _ which chaperone the hormone
binding proteins
because water soluble hormones can dissolve in blood, many circulate as __ meaning they are not attached by a binding protein
free hormones
water soluble hormones have _ lives
short half-lives
the life span of lipid soluble hormones in the blood ranges from
a few days to several weeks
what are the three types of stimuli that regulate hormone release
humoral
neural
hormonal
molecules and ions in the bloodstream can directly stimulate the release of some hormones. these chemicals are referred to as
humoral stimuli
specialized neuropeptides stimulate hormone secretion from other endocrine cells and are called
releasing hormones
occurs when a hormone is secreted that, in turn, stimulates the secretion of other hormones
hormonal stimuli
the most common examples of hormonal stimuli are hormones from the anterior pituitary gland called __ ; they stimulate the secretion of another hormone
tropic hormones
hormones from the hypothalamus that prevent the secretion of tropic hormones from the anterior pituitary gland are called
inhibiting hormones
hormones exert their actions by binding to target cell proteins called
receptors
the portion of each receptor molecule where a hormone binds is called a
receptor site
the tendency for each type of hormone to bind to one type of receptor and not to others is called
specificity
once lipid soluble hormones enter their target cell, they bind to
nuclear receptors
water soluble hormones are polar molecules and cannot pass through the cell membrane. instead, they interact with
membrane bound receptors
is produced inside a cell once a hormone or another chemical messenger binds to certain membrane bound hormones
second messengers
coordinated set of events is referred to as a
second messenger system
each receptor produces thousands of second messengers leading to a cascade effect and ultimately _ of the hormonal signal
amplification
also called the hypophysis ; a small gland about the size of a pea which is housed in a depression of the sphenoid bone inferior to the hypothalamus of the brain
pituitary gland
serves as a control center for the autonomic nervous system as well as the endocrine system
hypothalamus
the pituitary gland lies posterior to the optic chiasm and is connected to the hypothalamus by a stalk called
infundibulum
what are the divisions of the pituitary gland
anterior
posterior
what are the hormones of the anterior pituitary gland
growth hormone
thyroid stimulating hormone (TSH)
melanocyte stimulating hormone (MSH)
adrenocorticotropic hormone (ACTH)
luteinizing hormone (LH) ; gonadotropin
follicle stimulating hormone (FSH) ; gonadotropin
prolactin
what are the hormones of the posterior pituitary gland
antidiuretic hormone (ADH)
oxytocin
increases gene expression, breakdown of lipids, and release of fatty acids from cells ; increases blood glucose levels
growth hormone
increase thyroid hormone secretion (thyroxine and triiodothyronine)
thyroid stimulating hormone (TSH)
increases secretion of glucocorticoid hormones, such as cortisol ; increases skin pigmentation at high concentrations
adrenocorticotropic hormone (ACTH)
increases melanin production in melanocytes to make skin color darker
melanocyte stimulating hormone (MSH)
promotes ovulation and progesterone production in ovary ; promotes testosterone synthesis and support for sperm cell production in testis
luteinizing hormone
promotes follicle maturation and estrogen secretion in ovary ; promotes sperm cell production in testis
follicle stimulating hormone (FSH)
stimulates milk production and prolongs progesterone secretion following ovulation and during pregnancy in women ; increases sensitivity to LH in males ; helps promote development of breast during pregnancy
prolactin
conserves water ; constricts blood vessels
antidiuretic hormone
increases uterine contractions and increase milk letdown from mammary glands
oxytocin
a young person suffering from deficiency of GH remains small, although normally proportioned is called a
pituitary dwarf
the person becomes abnormally tall, a condition called
giantism
the facial features and hands become abnormally large, a condition called
acromegaly
the secretion of GH is controlled by __
two hormones from the hypothalamus
part of the effect of GH is influenced by a group of protein hormones called
insulin like growth factors or somatomedins
binds to membrane bound receptors on cells of thyroid gland and stimulates the secretion of thyroid hormone ; can stimulate growth of the thyroid gland ; increases metabolic rates essential for normal process of growth and maturation
thyroid stimulating hormone
ACTH increases the secretion of a hormone from the adrenal cortex called
cortisol or hydrocortisone
bind to membrane bound receptors on the cells of gonads ; regulate growth, development, and functions of the gonads
gonadotropins
what are the two major gonadotropins
luteinizing hormone
follicle stimulating hormone
in females, this gonadotropin hormone stimulates ovulation, promotes secretion of the reproductive hormones, estrogen, and progesterone. in males, it stimulates interstitial cells of the testes to secrete the reproductive hormone testosterone
luteinizing hormone
stimulates the development of follicles in the ovaries and sperm in the testes
follicle stimulating hormone
the thyroid gland synthesizes and secretes three hormones namely
triiodothyronine (T3)
thyroxine (T4)
calcitonin
the thyroid gland is made up of two lobes connected by a narrow band called the
isthmus
the thyroid glands contains numerous __ which are small spheres with walls composed of simple cuboidal epithelium
thyroid follicles
between the follicles is a network of loose connective tissue that contains capillaries and scattered
parafollicular cells or C cells
contains four iodine atoms and is abbreviated T4
thyroxine
contains three iodine atoms and is abbreviated T3
triiodothyronine
a lack of thyroid hormones is called
hypothyroidism
in infants, hyperthyroidism can result in __, characterized by a developmental delay, short stature, and abnormally formed skeletal muscles
cretinism
an elevated rate of thyroid hormone secretion is called __ ; causes an increased metabolic rate, extreme nervousness, and chronic fatigue
hyperthyroidism
an autoimmune disease that causes hyperthyroidism
graves disease
graves disease is often accompanied by bulging of eyes, a condition called
exophthalmia
are embedded in the posterior wall of the thyroid gland
parathyroid glands
the parathyroid glands secretes a hormone called __ which is essential for the regulation of blood calcium levels
parathyroid hormone (PTH)
what are the three effects of PTH
increases active vitamin D
increases blood Ca2+ levels
decreases loss of Ca2+ in the urine
an abnormally high rate of PTH secretion is called
hyperparathyroidism
an abnormally low rate of PTH secretion is called
hypoparathyroidism
are two small glands located superior to each kidney
adrenal glands
each adrenal gland has an inner part called the
adrenal medulla
each adrenal gland has an outer part called the
adrenal cortex
what hormones does the adrenal medulla secrete
epinephrine
norepinephrine
this hormone in the adrenal medulla accounts for 80% of the adrenal medulla
epinephrine
this hormone in the adrenal medulla accounts for 20% of the adrenal medulla
norepinephrine
epinephrine and norepinephrine are called the __ hormones ; they prepare the body for intense physical activity
fight or flight
what steroid hormones does the adrenal cortex secrete
mineralocorticoids
glucocorticoids
adrenal androgens
a type of steroid hormone that is produced in the greatest amounts
aldosterone
these steroid hormones cause lipid breakdown, reduce glucose and amino acid uptake in skeletal muscle
glucocorticoids
these steroid hormones stimulate the development of male secondary sex characteristics
adrenal androgens
the endocrine part of the pancreas consists of __ which are dispersed throughout the exocrine portion of the pancreas
pancreatic islets
the pancreatic islets consists of three cell types which are
alpha cells
beta cells
delta cells
secretes glucagon
alpha cellss
secretes insulin
beta cells
secretes somatostatin
delta cells
as lipids are broken down, the liver converts some of the fatty acids to acidic _
ketones
when blood glucose levels are very low, the breakdown of lipids can cause the release of enough fatty acids and ketones to reduce pH of the body fluids below normal, a condition called
acidosis
elevated blood glucose levels stimulate beta cells to secrete
insulin
the major target tissues for insulin are the liver, adipose tissue, muscles, and the area of the hypothalamus that controls appetite, called the
satiety center
a condition where the body cant regulate blood glucose levels within the normal range
diabetes mellitus
in type 1 diabetes mellitus, tissues cannot take up glucose effectively, causing blood glucose levels to become very high, a condition called
hyperglycemia
glucagon is released from the alpha cells when __
blood glucose levels are low
binds to membrane bound receptors primarily in the liver causing glycogen stored in the liver to be converted to glucose
glucagon
somatostatin is released by the delta cells in response to __
food intake
inhibits the secretion of insulin and glucagon and inhibits gastric tract activity
somatostatin
the main reproductive hormone in the male is __ 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 an secondary sexual characteristics
testosterone
in female, the two main classes of reproductive hormones secreted by the ovaries are
estrogen
progesterone
organ that lies in the upper part of the thoracic cavity ; it is important in the function of the immune system
thymus
the thymus secretes a hormone called
thymosin
organ that is small, pinecone shaped, located superior and posterior to the thalamus of the brain
pineal gland
the pineal gland produces a hormone called __ which inhibit the reproductive hypothalamic releasing hormone, gonadotropin-releasing hormone
melatonin
