Download Chapter 45 Worksheet Sy Ha Hormones and the Endocrine System

Chapter 45 Worksheet
Hormones and the Endocrine System
Sy Ha
An Introduction to Regulatory System
1. Compare the response times of the two major systems of internal communication: the nervous
and the endocrine system.
The response time of the nervous system is involved with high speed messaging as the body
needs it quickly while the endocrine system is slower as it needs to do more activities such as
connecting to a receptor, producing the required substances, releasing it, and the movement of
the message.
2. Distinguish between the endocrine and exocrine glands.
The endocrine glands are ductless glands that secretes hormones directly into the interstitial
fluid, from which they diffuse into bloodstream and to wherever they need to go whereas the
exocrine glands that is secreted externally through a duct.
3. Explain how neurosecretory cells, epinephrine, and the release of milk by a nursing mother
illustrate the integration of the endocrine and nervous system.
The neurosecretory cells, epinephrine, and release of milk illustrate the integration by creating a
neurohormone pathway that regulates the release of milk. The neurosecretory cells work to
create the hormone oxytocin which is stimulated from the suckling of the baby for milk. This
nerve impulse starts the endocrine system in order to provide the baby with milk which is
regulated by the oxytocin hormone.
4. Describe several examples of the essential roles of hormones in the maintenance of
homeostasis.
Hormones play an important role in maintaining homeostasis or keeping the body under normal
conditions. For example, the control of blood glucose is controlled by insulin and glucagon.
Insulin triggers uptake of glucose from blood decreasing glucose levels in blood when it is high
and glucagon triggers release of glucose into blood increasing glucose levels when they are low.
Another example is the temperature of the human body which is controlled by hypothalamus.
The hypothalamus monitors the temperature and sends hormones to cell in order to tell them to
take up more ATP or take up less ATP in order to raise heat or lower it.
Chemical Signals and Their Modes of Action
5. Distinguish between the functions of local regulators and pheromones.
Local regulators are secreted molecules that go short distances to reach target cells through
diffusion while pheromones are chemicals released to outside environment in order for animals
to communicate with other animals via smell.
6. Describe the diverse functions of growth factors, nitric oxide, and prostaglandins.
Growth factors stimulate growth and cell production through the use of tropic and nontropic
effects. Nitric oxide, which consists of nitrogen double-bonded to oxygen, serves as both a
neurotransmitter and local regulator. For example, when oxygen levels fall in blood, NO is
released which activates enzyme that relaxes smooth muscle cells, resulting in better blood flow.
Prostaglandins, modified fatty acids, also have many modified activities. For example, during
sex, prostaglandins are released in order to activate the smooth muscles of the females uterine
wall to help sperm cells move through to egg and baby get out. In the immune system,
prostaglandins promote fever and inflammation and also intensifies the sensation of pain. It also
helps regulate the aggregation of platelets.
7. Define a signal transduction pathway, noting the mechanism and main components of action.
Give several examples of its function.
A signal transduction pathway are a series of changes in cellular proteins that converts
extracellular chemical signal to a specific intracellular response. It occurs after binding to the
receptor and goes through a series of steps in order to create the response needed. For example,
epinephrine from the adrenal glands binds to G protein-coupled receptors in plasma membrane
of liver cell to trigger a response to stress. It goes through a series of steps involving cAMP and
activation of protein kinase A by cAMP to activate enzyme for glycogen breakdown and
inactivation in order to provide fuel to handle the stress.
8. Describe the nature and locations of intracellular receptors for hormones that pass easily
through cell membranes. Explain how their passage compares to the signal-transduction pathway
noted just above.
Hormones that pass easily through the cell membrane are lipid soluble hormones. Receptors for
these types of hormones are located within the cell; therefore, these hormones pass through the
plasma membrane of cell in order to bind to these receptors. On the other hand, signal
transduction pathways bind to receptors located on the plasma membrane in order to activate
these types of reactions.
9. Describe the several examples of different physiological reactions in animals exposed to the
same hormone.
Animals can react differently when exposed to the same hormone. Many hormones have multiple
effects on animals and could also have different effects on different animals. For example,
tissues in animals vary in their response to adrenaline. Adrenaline causes some of the tissues to
contract and others to restrict blood flow. An example of a given hormone having a different
effect for a different species is thyroxine. Thyroxine helps to regulate metabolism in many
animals but frogs also use thyroxine in order to help them in the resorption of the tadpole’s tail to
turn to adult.
The Vertebrate Endocrine System
10. Explain how the hypothalamus and pituitary glands interact and how they coordinate the
endocrine system.
The hypothalamus and pituitary glands interact within the endocrine system. The hypothalamus
sends signals to the pituitary glands in order for them to release these hormones. For example, if
the hypothalamus sends the pituitary gland a signal to release the oxytocin hormone, then the
posterior part of the pituitary gland will release it.
11. Describe the location of the pituitary. List and explain in detail the functions of the hormones
released from the anterior and posterior lobes.
The pituitary gland is located at the base of the hypothalamus.
Anterior
Posterior
growth hormones - stimulates bone growth and
metabolic functions
oxytocin - stimulates contraction of uterus
and regulation of milk release
prolactin - stimulation of milk production and
secretion
antidiuretic hormone - promotes retention
of water in kidney
follicle stimulating hormone - stimulation of ova
and sperm
luteinizing hormone - stimulates ovaries and testes
thyroid stimulating hormone - stimulates thyroid
gland
adrenocorticotropic hormone - stimulates adrenal
cortex to secrete glucocorticoids
12. Describe the location of the pineal gland. Explain the significance of its secretion melatonine
The pineal gland is a small mass of tissue located in the center of the brain. This gland helps
secretes melatonin. Melatonin is significant because it regulates function related to light and to
seasons marked by changes in daylight. Basically, it is controlled by the light/dark cycles of the
seasons. If night is longer, then melatonin is released more.
13. List the hormones of the thyroid gland and explain their roles in development and
metabolism. Explain the causes and symptoms of hyperthyroidism, hypothyroidism, and goiter.
Triiodothyronine
(T3)
This helps to stimulate and maintain metabolic processes.
thyroxine (T4)
(same as above) Most of the time one iodine is removed from it to
produce (T3)
Calcitonin
Lowers blood calcium levels
Hyperthyroidism is caused by excessive secretion of the thyroid hormones. This causes high
body temperature, profuse sweating, weight loss, irritability, and high blood pressure.
Hypothyroidism results from having too little thyroid function. Symptoms include weight gain,
lethargy, and intolerance to cold. Goiter results from the swelling of the thyroid gland. This
results in the neck or voice box.
14. Note the location of the parathyroid glands and describe the hormonal control of calcium
homeostasis.
The parathyroid glands are located in the posterior surface of the thyroid. This plays a major role
in calcium homeostasis because of the release of parathyroid hormone (PTH). Whenever calcium
blood levels fall below set point, PTH is released and raises the calcium levels in blood through
direct and indirect means. Directly, PTH stimulates calcium reabsorption through the renal
tubules and indirectly influences it by promoting creation of Vitamin D.
15. Distinguish between alpha and beta cells in the pancreas and explain how their antagonistic
hormones (insulin and glucagon) regulate carbohydrate metabolism.
Alpha cells make glucagon whereas beta cells create insulin. These antagonistic hormones
(insulin and glucagon) help regulate carbohydrate metabolism by having opposite effects. Insulin
triggers the uptake of glucose from blood, decreasing blood glucose levels, while glucagon
promotes release of glucose from blood, increasing blood glucose levels. These opposite effects
balance the blood glucose levels; there won’t be too much or too little.
16. Distinguish between Type I diabetes mellitus and Type II diabetes mellitus.
Type I diabetes mellitus occurs mostly during childhood. This autoimmune disorder occurs when
the immune system destroys the beta cells of the pancreas, thus, causing a lack of insulin. This
lack of insulin causes a high level of blood glucose levels. This can be treated through injection
of insulin. Type II diabetes mellitus occurs during middle age. It occurs when target cells fail to
respond normally to insulin. Insulin is still produced but cells fail to take in glucose. This causes
blood glucose levels to remain.
17. Describe the development of the adrenal medulla. List the hormones of the adrenal medulla,
describe their functions, and explain how their secretions are controlled.
The adrenal medulla is the central portion of the adrenal glands. This develops from neural
tissues during embryonic development. The adrenal medulla produces epinephrine and
norepinephrine. These hormones are created in response to stress. These hormones help create
more energy by increasing the availability of energy sources in order to deal with the stress. This
is controlled by neurons which send them impulses to activate whenever stress appears.
18. List the hormones of the adrenal cortex, describe their functions, and explain how their
secretions are controlled.
The adrenal cortex produces the glucocorticoids and mineralocorticoids. The glucocorticoids is a
steroid that raises blood glucose levels. The mineralocorticoids are steroids that promote
reabsorption of Na+ and K+ in kidneys. Glucocorticoids is regulated by ACTH,
Adrenocorticotropic hormone, and the mineralocorticoids are regulated by K+ in blood and
angiotensin II.
19. List the hormones of three categories of steroid hormones produced by the gonads. Describe
variations in their production between the sexes. Note the functions of each category of steroid
and explain how secretions are controlled.
Androgens Produced by testes (males) mainly testosterone and functions by helping develop
male secondary sex characteristics during puberty
Estrogens
Mainly estradiol; responsible for maintenance of female reproductive system and
development of female sex characteristics
Progestins
Mainly progesterone; function is to prepare and maintain tissues of uterus for
growth and support of embryo
Secretions are controlled through cascade pathways. They are synthesized by gonadotropins
(FSH and LH) from the pituitary glands which is in turn controlled by the hypothalamus.
Key Terms
hormone - molecule that is secreted into the extracellular fluid, circulates in the blood or
hemolymph, and communicates regulatory messages throughout the body
target cell - cell that has receptors for a hormone to latch on and give signal to the cell
endocrine system - body system that is used for communication and regulation of the body
endocrine glands - ductless regions that hold endocrine cells
nuerosecretory cells - cell in the nervous system that produces a hormone
ecdysone - hormone that is released by the prothoracic glands that promotes molting during
metamorphosis of insects (ex: caterpillar into a butterfly)
brain hormone (BH) - A hormone, produced by neurosecretory cells in the insect brain, that
promotes development by stimulating the prothoracic glands to secrete ecdysone.
juvenile hormone - signaling molecule secreted by the corpora allata that indirectly influences
development by modulating the activity of ecdosine
growth factor - substance that stimulate cell proliferation and differentiation
nitric oxide (NO) - gas that consists of nitrogen double bonded to oxygen that serves as a nuero transmitter and local regulator
prostaglandins (PGs) - group of local regulators (fatty acids) that serve various actvities such as
stimulating smooth muscles of female’s uterine wall to contract in order to help sperm reach egg,
etc.
signal-transduction pathway - series of changes in cellular proteins that converts extracellular
chemical signal to a specific intracellular response
tropic hormones - hormones that regulates the function of endocrine cells or glands
hypothalamus - endocrine gland located in the brain that plays important role in integrating
endocrine and nervous system
pituitary gland - gland located at base of hypothalamus
anterior pituitary - gland that develops from fold of tissue at the roof of the embryonic mouth and
grows upward towards brain and releases hormones
adenohypophysis - another name for the anterior pituitary
releasing hormone - hormone that is released by hypothalamus that speeds up secretion of a
given hormone by anterior pituitary
inhibiting hormone - hormone that is released by hypothalamus that inhibits secretion of a
hormone
posterior pituitary - extension of hypothalamus that grows downward toward mouth and secretes
two hormones made by hypothalamus
neurohypophysis - another name for the posterior pituitary
oxytocin - hormone that is released by posterior hormones that regulates milk release during
milking
antidiuretic hormone (ADH) - hormone that is released by posterior hormones that helps regulate
blood osmolarity
growth hormone (GH) - hormone secreted by anterior pituitary that stimulates growth through
tropic and nontropic effects
insulinlike growth factors (IGFs) - hormone released by liver that is responsible for building
muscle
prolactin (PRL) - nontropic hormone that has diversity of various effects among vertebrate
species such as stimulating gland growth and milk synthesis
follicle-stimulating hormone (FSH) - tropic hormone that stimulates activities of the male and
female gonads
luteinizing hormone (LH) - tropic hormone that stimulates activities of the male and female
gonads
thyroid-stimulating hormone (TSH) - hormone released by anterior pituitary that helps regulate
function of thyroid gland
gonadotropins - group of hormones secreted by pituitary that stimulates activity of gonads
adrenocorticotropic hormone (ACTH) - tropic hormone that stimulates secretioni and production
of steroid hormones by adrenal cortex
melanocyte-stimulating hormone (MSH) - nontropic hormone that regulates activity of pigmentcontaining cells in skin of amphibians as well as fish and reptiles
endorphin - group of hormones produced in brain and anterior pituitary that inhibits pain
perception
pineal gland - small gland that is located on the dorsal surface of brain that secretes melatonin
hormone
melatonin - hormone released by pineal gland that regulates body functions related to seasonal
day length
thyroid gland - gland consisting of two lobes on ventral surface of trachea that regulates
homeostasis and development
triiodothyronine (T3) - hormone consisting of three iodine atoms that is produced by the thyroid
gland and play a role in development and maturation
thyroixine (T4) - hormone containing four iodine atoms (one atom removed to make T3) and
plays a role in development and maturation
calcitonin - hormone released by thyroid gland that inhibits bone resorption and enhances
calcium ion (Ca2+) release by kidney
parathyroid glands - set of four small structures embedded in posterior surface of thyroid that
plays major role in blood calcium ion (Ca2+) regulation
parathyroid hormone (PTH) - hormone released by parathyroid glands when blood Ca2+ falls
below set point
vitamin D - steroid molecule that is obtain from food or synthesized in skin from exposure to
sunlight and helps stimulate uptake of Ca2+ from food and helps augment effects of PTH
pancreas - gland that has following functions: the nonendocrine portion functions by helping in
digestion, secretion of enzymes, and alkaline solution into small intestine via a duct; the ductless
endocrine portion function by helping in homeostasis by secreting hormones of insulin and
glucagon into blood
islets of Langerhans - endocrine cells located in pancreas that uses alpha and beta cells that make
insulin and glucagon
alpha cells - cells that help make glucagon in pancreas
glucagon - hormone released from pancreas that promotes release of glucose into blood
increasing blood glucose concentration
beta cell - cells that make insulin in pancreas
insulin - hormone released by pancreas that triggers uptake of glucose into blood decreasing
blood glucose concentrationconra
Type I diabetes mellitus - autoimmune disorder that mostly occurs during childhood that
destroys person’s ability to make insulin
Type II diabetes mellitus - disorder that occurs when there is a failure of target cells to respond
normally to insulin
adrenal gland - glands located in kidneys that contains adrenal cortex and adrenal medulla
adrenal cortex - gland in kidney that releases corticosteroids such as glucocorticoids,
mineralocorticoids, and sex hormones
adrenal medulla - gland in kidney that releases epinephrine and norepinephrine in response to
stress
epinephrine - hormone (adrenaline) released by adrenal medulla that stimulates fight-or-flight
response in response to short term stress
norepinephrine (noradrenaline) - hormone that functions similarly to adrenaline and acts as a
hormone or nuerotransmitter
catecholamines - class of amine hormones synthesized from amino acid tyrosine (epinephrine
and norepinephrine is part of this class)
corticosteroids - any steroid hormone produced and secreted by adrenal cortex
glucocorticoids - steroid hormone that is secreted by adrenal cortex and influences glucose
metabolism and immune function
mineralocorticoids - steroid hormone that is secreted by adrenal cortex and regulates salt and
water homeostasis
androgens - any steroid hormone that stimulates development and maintenance of male
reproductive system and secondary sex characteristics
testosterone - steroid hormone required for development of male reporductive system,
spermatogenesis, and male secondary sex characteristics
estrogens - any steroid hormone that stimulates development and maintenance of female
reproductive system and secondary sex characteristics
progestins - steroid hormone with progesterone like activity