Endocrine System Flashcards
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
hormones
Hormones circulate through the
bloodstream to specific sites called
target tissue or effectors
the term endocrine (EN-
doh-krin) —derived from the Greek words
endo; within, krino; to secrete
The study of the endocrine system, known as
endocrinolog
The body has a remarkable capacity for maintaining homeostasis despite having to coordinate the activities of nearly
40 trillion cells
allow cells to communicate with each other to regulate body activities.
Chemical messengers
Most chemical messengers are produced by a specific collection of
cells or gland
Two important control system of the body
Endocrine System and Nervous System
are secreted in response to humoral, neural, or
hormonal stimuli to regulate homeostasis
Hormones of the endocrine system
Fullness
Satiation
hormone is derived from the Greek word _______, which means to _______
hormon; set into motion
Two chemical categories of hormones
Lipid-soluble and Water-soluble
derived from cholesterol
Steroid hormones
derived from the amino acid tyrosine
thyroid hormones
are nonpolar, and include steroid hormones, thyroid
hormones, and fatty acid derivative hormones, such as certain eicosanoids.
Lipid-soluble hormones
are polar molecules; they include protein hormones,
peptide hormones, and most amino acid derivative hormones.
Water-soluble hormones
dissolve directly into the blood and are delivered
to the target tissue without g to binding protein
Large hormones
however need attachment to larger protein to avoid being filtered out of the blood.
small hormones
Receptor Location of Lipid-soluble hormones:
Nucleus or Cytoplasm
Receptor Location of Water-Soluble:
Plasma membrane’s outer surface
It diffuses across the cell membrne
Lipid-soluble hormones
cannot diffuse through cell membrane
Water-soluble hormone
There are three types of stimuli which regulate
hormone release
Humoral, Neural, Hormonal
Blood-borne chemicals which stimulate release of
some hormones are called
Humoral Stimuli
Following an action potential, neurons release a
neurotransmitter into the synapse. Neurotransmitters will allow stimulation of the gland to release hormone where it will travel to its target.
Neural Stimuli
It occurs when a secreted hormone stimulates the
secretion of other hormones. These hormones are
called
tropic hormones
It occurs when a secreted hormone stimulates the
secretion of other hormones. These hormones are
called
tropic hormones
There are hormones that prevents the secretion of
other hormones. These hormones are called
inhibiting hormones
pituitary gland is also called the
Hypophysis
Hormones exert their actions by binding to target cell proteins called
receptors
The portion of each receptor molecule where a hormone binds is called
receptor site
The tendency for each type of hormone to bind to one type of receptor, and not to others, is called
specificity
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 the
Infundibulum
The pituary gland is divided into two parts:
Anterior pituitary, posterior pituitary
is made up of epithelial cells derived from the embryonic oral cavity
Anterior pituitary
is an extension of the brain adn is composed of neurons
posterior pituitary
hormones from the hypothalamus that prevent the secretion of tropic hormones from the anterior pituitary gland are called
inhibiting hormones
It occurs when a secreted hormone stimulates the
secretion of other hormones. These hormones are
called tropic hormones.
Hormonal Stimuli
known as the body’s master gland
pituitary gland
known as the body’s master gland
pituitary gland
hypothalamus controls the pituitary gland in two ways:
(1) hormonal control and (2) direct innervation.
The capillary beds and veins that transport the releasing and inhibiting hormones are called the
hypothalamic-pituitary portal system
stimulates the growth of bones, muscles, and other
organs by increasing gene expression.
Growth Hormone (GH)
A young person suffering from a deficiency of growth hormone remains small, although normally proportioned, and is called a
pituitary dwarf
If excess growth hormone is present before bones finish growing in length, exaggerated bone growth occurs. 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
Hormone release caused by altered levels of certain ions or nutrients
Humoral Stimulus
Hormone release caused by neural input.
Neural Stimulus
Hormone release caused by another hormone (tropic hormone)
Hormonal Stimulus
In addition to growth hormone, genetics, nutrition, and reproductive hormones influence growth.
Part of the effect of growth hormone is influenced by a group of protein hormones called
insulin-like growth factors (IGFs) or somatomedins
binds to membrane-bound receptors on cells of the thyroid gland and stimulates the secretion of thyroid hormone. It can also stimulate growth of the thyroid gland.
Thyroid-stimulating hormone (TSH)
binds to membrane-bound receptors on cells of the adrenal cortex.
Adrenocorticotropic hormone (ACTH)
ACTH increases the secretion of a hormone from the adrenal cortex called
Cortisol/Hydrocortisone
bind to membrane-bound receptors on the cells of the gonads (ovaries and testes). It regulate the
growth, development, and functions of the gonads.
Gonadotropins
The two major gonadotropins are
Luteinizing Hormone (LH) and Follicle-stimulating hormone (FSH)
In females, it stimulates ovulation. It also
promotes the secretion of the reproductive hormones, estrogen and progesterone,
from the ovaries. In males, it stimulates interstitial cells of the testes to secrete the reproductive hormone testosterone.
Luteinizing Hormone (LH)
It stimulates the development of follicles in the ovaries and sperm cells in the testes.
Follicle-stimulating hormone (FSH)
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
Prolactin
binds to membrane-bound receptors on melanocytes and causes them to synthesize
melanin.
Melanocyte-stimulating hormone (MSH)
binds to membrane-bound receptors and increases water reabsorption by kidney tubules. This results in less water lost as urine. It can also cause blood vessels to constrict when released in large amounts.
Antidiuretic (ADH) or vasopressin
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
Thyroid gland synthesizes and secretes three
hormones:
(1) triiodothyronine (T3), (2) thyroxine (tetraiodothyronine; T4), and (3) calcitonin.
The thyroid gland is made up of two lobes
connected by a narrow band called
isthmus
- One of the largest endocrine glands.
• Appears more red than surrounding tissues.
• Main function: Secretion of thyroid hormones
Thyroid gland
Thyroid hormones are synthesized and stored
within the thyroid follicles. These follicles contain protein called ___________ in which hormones are attached.
thyroglobulin
The synthesized hormones in these follicles are
thyroxine/tetraiodothyronine(T4) and
triiodothyronine (T3)
small spheres with walls composed of simple cuboidal epithelium
thyroid follicles
contains four iodine atoms and is abbreviated T4.
Thyroxine or tetraiodothyronine
contains three iodine atoms and is abbreviated T3.
triiodothyronine
Loss of negative feedback will result in excess
TSH. It causes enlargement of the thyroid. This
condition is called
goiter
lack of thyroid hormones
hypothyroidism
In infants, hypothyroidism can result in
cretinism
In adults, the lack of thyroid hormones results in a
decreased metabolic rate, sluggishness, reduced ability to perform routine tasks and myxedema.
elevated rate of thyroid hormones
Hyperthyroidism
a type of of hyperthyroidism that results when the immune system produces abnormal proteins that are similar in structure and function to TSH.
Grave’s Disease
Graves disease is often accompanied by bulging
of the eyes, a condition called
Exophthalmia
are embedded in the posterior wall of the thyroid gland
four tiny parathyroid glands
The parathyroid glands secrete a hormone called
parathyroid hormone (PTH)
low rate of PTH
• Results from injury to or the surgical removal of
thyroid and parathyroid glands.
Hypoparathyroidism
elevated rate of PTH
• Causes softening, deformity and/or fracture of the
bone.
Hyperparathyroidism
are two small glands located superior to each kidney
adrenal glands
inner part of adrenal gland
adrenal medulla
outer part of adrenal gland
adrenal cortex
accounts for 80% of the adrenal medulla secretions
epinephrine
accounts for 20% of the medulla secretions
norepinephrine
regulate ion balance in the blood. These are the major secretory products of the zona glomerulosa of the adrenal cortex.
Mineralocorticoids
is produced in the greatest amounts, although other, closely related mineralocorticoids are also secreted. This is secreted under low blood pressure conditions.
Aldosterone
regulates blood volume and levels of potassium and sodium ions.
Mineralocorticoids
Binds to receptor molecules in the kidney, but it also
affects the intestine, sweat glands and salivary
glands. It causes sodium ions and water to be
retained in the body.
Aldosterone
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. Also increase blood glucose levels and glycogen deposits in cells.
Glucocorticoid
Major hormone of Mineralocorticoids
Aldosterone
Major hormone of Glucocorticoids
Cortisol
Responds in stressful situations. Increases the breakdown of proteins and lipids. It also increases their conversion to forms of energy the body can use.
Cortisol
Reduces inflammatory and immune responses.
Cortisone
Stimulate the development of male sexual
characteristics. However, both male and female possess these hormones. Abnormally high level of this hormone can exaggerate male characteristics in both male and female.
Gonadocorticoids - Androgens
consists of pancreatic islets, which are dispersed throughout the exocrine portion of the pancreas
endocrine part of pancreas
Consists of the pancreatic islets (Islets of
Langerhans).
pancreas
secretes glucagon
alpha cells
secretes insulin
beta cells
secretes somatostatin
delta cells
These islets secrete three hormones:
1) insulin, 2) glucagon, and 3) somatostatin
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 the pH of
the body fluids below normal, a condition called
acidosis
This will cause tissues to break down lipids and proteins to provide an alternative source of energy.
Decreased blood glucose level
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
The kidneys produce large volume of urine
containing substantial amount of glucose. However,
dehydration can result because of rapid loss of
water in the form of urine.
Increased blood glucose level
• Released from the beta cells
• Major target tissues: liver, adipose tissue,
muscle and satiety area of hypothalamus.
• Effects:
• Increases when there is elevated blood glucose level
• Increases in response to parasymphatetic
stimulation associated with digestion
• Increases when there is an increased blood levels of certain amino acids
Insulin
is the body’ s inability to regulate blood glucose levels within the normal range.
Diabetes mellitus
Occurs when too little insulin is secreted from
the pancreas.
Type 1 Diabetes Mellitus
Occurs when lack of number of insulinreceptors on target cells or defective target cells do not respond normally to insulin
Type 2 Diabetes Mellitus
• Released from the alpha cells
• Binds to membrane-bound receptors of the
liver, causing glycogen to convert to glucose.
Glucagon
released into the bloodstream
glucose
• Released from the delta cells
• Response to food intake
• Inhibit secretion of insulin and glucagon
• Inhibits gastric activity.
Somatostatin
are structures of the reproductive tract which
has an essential role in reproduction.
testes (male), ovaries (female)
main reproductive hormone in the male is
testosterone
the female, two main classes of reproductive hormones, secreted by the ovaries, affect sexual characteristics:
estrogen and progesterone
male sex hormone testosterone is secreted by
testes
These hormones work togetheron the growth and development of the female reproductive structures, breasts, hips, thighs and as well as sexual characteristics.
estrogen and progesterone
lies in the upper part of the thoracic cavity which functions in immunity.
Thymus
It secretes the hormone “thymosin” which aids
in the development of the T-cells.
Thymus
Thymus secretes a hormone called
Thymosin
is a small, pinecone-shaped structure located superior and posterior to the thalamus of the brain
pineal gland
Pineal gland produces hormone called
melatonin
decreases secretion of LH and FSH
melatonin
