Download Endocrine System

Endocrine System
Kelsey Jackson
AD Bradley
Hailey Bell
Period 3
Functions of Endocrine System
• Regulating the functions of the body to maintain
homeostasis.
• Coordinate with the nervous system functions.
• Oversee cell to cell communication using
chemical signals.
Characteristics
• Like the nervous system, the endocrine system
exerts precise effects in helping regulate
metabolic processes.
• The Endocrine System includes cells, tissues,
and organs that make up a network of glands
that secrete hormones, which travel in the blood
stream and affect the functioning of target cells
Nervous System vs. Endocrine System
Secretions
• Paracrine secretions act locally, only affecting
neighboring cells.
• Autocrine secretions act on cells that make
them, only the secreting cell itself.
• Exocrine glands secrete through tubes and
ducts.
Major Endocrine Glands
Hormone Action
• Endocrine glands secrete hormones that affect
target cells with specific receptors
• Chemical hormones are:
▫
▫
▫
▫
▫
Steroids
Amines
Peptides
Proteins
Glycoproteins
Steroid Hormones
• Steroid hormones enter a target cell and bind
receptors forming complexes in nucleus.
• Complexes activate specific genes so that specific
proteins synthesize.
The following events occur:
1. The lipid-soluble steroid hormone diffuses
through the cell membrane
2. The steroid hormone binds a specific protein
molecule-the receptor for that hormone.
3. The resulting hormone-receptor complex binds
within the nucleus to particular regions of the
target cell’s DNA and activities transcription of
specific genes into messenger RNA (mRNA)
molecules.
4. The mRNA molecules leave the nucleus and
enter the cytoplasm.
5. The mRNA molecules associate with ribosomes
to direct the synthesis of specific proteins.
Steroid Hormones
Non Steroid Hormones
The mechanism works as follows:
1. A hormone binds its receptor.
2. The resulting hormone-receptor complex
activates a protein called a G protein.
3. The G protein activates an enzyme called
adenylate cyclase, which is a membrane
protein.
4. Activated adenylate cyclase catalyzes the
circularization of ATP in the cytoplasm into
cAMP.
Nonsteroid Hormone
Control of Hormone Secretions
• Concentration of each hormone is regulated in
the body
• Endocrine glands secrete hormones in response
to hormones that the hypothalamus secretes
• Other glands secrete hormones in response to
nerve impulses
• Negative feedback mechanisms guide these
hormone secretions
• Glands sense hormone concentration
Control of Hormone Secretions
• If hormone secretion reaches a certain
concentration the gland is inhibited and can no
longer secrete
• Negative feedback systems maintain stable
hormone concentrations
Pituitary Gland
• Anterior pituitary hormones
- Secretes growth hormones, prolactin, thyroidstimulating hormone, adrenocorticotropic
hormone, follicle-stimulating hormone and
luteinizing hormone
• Growth hormones
- Stimulates cells to grow and divide more
frequently
Pituitary Gland
Pituitary Hormones
• Prolactin
- Stimulates and sustains women’s milk
production
• Thyroid stimulating hormones
- Controls secretion of hormones from thyroid
gland
- Hypothalamus secretes throtropin-releasing
hormones that regulates thyroid stimulating
hormones
Adrenocorticotropic Hormone
• ACTH controls secretion of hormones from the
adrenal cortex
• The hypothalamus secretes thyrotropinreleasing
• Hypothalamus secretes corticotropin-releasing
hormone that regulates thyroid secreting
hormones
Posterior Pituitary Hormones
• Posterior lobe of pituitary gland consists largely
of neurological cells and nerve fibers
• Hypothalamus produces hormones of the
posterior pituitary
• Antidiuretic hormone reduces volume of water
that the kidney excretes
Oxycotin
• Oxycotin contracts muscles in the uterine wall
• Also contracts cells associated with producing
and ejecting milk
Thyroid Gland
•
•
•
•
Consists of two lobes in the neck
Includes many follicles
The follicles are fluid filled and store hormones
Thyroid Hormones
- Thyroxine and triiodothyronine increase the
metabolic rate of cells, enhance protein
synthesis and stimulate lipid utilization
- Calcitonin helps regulate concentrations of
blood calcium and phosphate ions
Thyroid Gland
Parathyroid Glands
• Located on the posterior surface of the thyroid
gland
• Structure
- Each parathyroid gland consists of secretory
cells that are well supplied with capillaries
• Parathyroid Hormone
- Parathyroid hormones increase blood calcium
level and decrease blood phosphate ion
concentration
- Negative feedback mechanisms operate
between parathyroid glands and the blood
Adrenal Glands
• Adrenal glands are closely associated with the
kidneys.
• Located atop each kidney like a cap and is
embedded in the mass of adipose tissue that
encloses the kidney.
Structure of Adrenal Glands
• Each gland consists of an adrenal medulla and
an adrenal cortex.
• The glands are functionally distinct and secrete
different hormones.
Hormones of Adrenal
Adrenal Glands
Hormones of Adrenal Medulla and
Adrenal Cortex
Medulla:
1. Cells of adrenal medulla secrete epinephrine
(adrenalin) and norepineephrine.
Cortex:
1. Produces several steroid hormones
2. Aidosterone is a mineralocorticoid that cause
the kidneys to conserve sodium ions and water
to secrete potassium ions.
Adrenal Sex Hormones
• These hormones are male types, adrenal
androgens, but some are converted to female
hormones, estrogens, in the skin, liver, and
adipose tissue.
• May supplement the supply of sex hormones
from the gonads and stimulate early
development of reproductive organs.
Pancreas
• Structure
- Attached to small intestine
- Pancreatic islets secrete glucagon and insulin
• Hormones of the pancreatic islets
- Glucagon stimulates the liver to produce
glucose from glycogen and non-carbohydrates
- Insulin moves glucose across cell membranes
that stimulate glucose and fat storage and
promotes protein synthesis.
Pancreas
Pineal Gland
• Attaches to the thalamus
• Secretes melatonin in response to varying light
conditions
• Melatonin may help regulate the female
reproduction cycle by inhibiting gonadotropin
secretion from the anterior pituitary.
Thymus Gland
• Lies between the sternum and between the lungs
• Secretes thymosins, which affect the productions
of certain lymphocytes that function in
immunity
Reproductive Glands
• Ovaries secrete estrogens and progesterone and
gonadotropin
• Testes secrete testosterone
Digestive Glands
• Certain glands of the stomach and small
intestine secrete hormones
Other hormone producing glands
• The heart and the kidneys produce hormones
Stress and Health
• Types of stress
-Physical stress results from environmental
factors that are harmful to tissues
- Psychological stress results from thoughts
about real or imagined dangers
• Response to stress
- Responses to maintain homeostasis
- Hypothalamus controls general stress
syndrome
Endocrine System Diseases
Diabetes- One of the more prevalent endocrine
system diseases, diabetes is a condition in which
the pancreas does not produce enough of the
hormone insulin or the body does not effectively
use the insulin it does produce. Because insulin
is instrumental in helping the body convert
sugars and starches into necessary energy, there
can be serious consequences if diabetes is left
undiagnosed and/or untreated.
Endocrine System Diseases
Cushing’s Syndrome- Cushing's syndrome, less
common than the endocrine system diseases
discussed above, occurs as the result of too much
Cortisol in the blood for an extended period of
time. Cortisol is a hormone that, in normal
amounts, helps the body perform a number of
important functions including converting fat
into energy, maintaining immune system
function, and responding to stress.
Endocrine System Diseases
Growth Disorders- Given that the endocrine
system regulates growth processes, endocrine
system diseases often result in growth disorders.
If the body produces too much growth hormone
(GH), gigantism or acromegaly (gigantism in
adults) can occur; too little growth hormone
results a condition called growth hormone
deficiency, or GHD, which can cause children to
grow more slowly than normal.
Work Cited
• Raji, Annaswamy. "Endocrine System Diseases: Cushing's
Syndrome, Addison's Disease and More." Endocrine System
Diseases, Symptoms & Treatment: The Hormone Health Network.
The Endocrine Society, n.d. Web. 21 Mar. 2013.
<http://www.hormone.org/endocrine_system_diseases.cfm>.
• Shier, David, Jackie Butler, and Ricki Lewis. "Endocrine System."
Hole's essentials of human anatomy and physiology. 9th ed.
Boston: McGraw-Hill, 2006. 276-301. Print.
• Images courtesy of Hole’s essential of human anatomy and
physiology.