ENDOCRINE SYSTEM Flashcards by Bianca Balandra

is composed of endocrine glands and specialized endocrine cells located throughout the body

endocrine system

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hormones circulate through the bloodstream to specific sites called

target tissues

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allow cells to communicate with each other to regulate body activities

chemical messengers

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what are the types of chemical messengers

autocrine chemical messengers
paracrine chemical messengers
neurotransmitters
endocrine chemical messengers

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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

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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

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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

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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

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two categories of hormones

lipid soluble
water soluble

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these type of hormones are nonpolar and include steroid, thyroid, and fatty acid derivative hormones

lipid soluble hormones

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lipid soluble hormones travel into the bloodstream bound to _ which chaperone the hormone

binding proteins

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because water soluble hormones can dissolve in blood, many circulate as __ meaning they are not attached by a binding protein

free hormones

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water soluble hormones have _ lives

short half-lives

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the life span of lipid soluble hormones in the blood ranges from

a few days to several weeks

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what are the three types of stimuli that regulate hormone release

humoral
neural
hormonal

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molecules and ions in the bloodstream can directly stimulate the release of some hormones. these chemicals are referred to as

humoral stimuli

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specialized neuropeptides stimulate hormone secretion from other endocrine cells and are called

releasing hormones

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occurs when a hormone is secreted that, in turn, stimulates the secretion of other hormones

hormonal stimuli

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the most common examples of hormonal stimuli are hormones from the anterior pituitary gland called __ ; they stimulate the secretion of another hormone

tropic hormones

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hormones from the hypothalamus that prevent the secretion of tropic hormones from the anterior pituitary gland are called

inhibiting hormones

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hormones exert their actions by binding to target cell proteins called

receptors

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the portion of each receptor molecule where a hormone binds is called a

receptor site

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the tendency for each type of hormone to bind to one type of receptor and not to others is called

specificity

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once lipid soluble hormones enter their target cell, they bind to

nuclear receptors

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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