Download Endocrine System

Endocrine System
Created By:
Lauren Covey, Sophia Yang, Delaney
Sullivan, Lena Tahir, Michael Chen
General Characteristics
• The main functioning unit of the endocrine
system is the hormone.
– Travels through interstitial fluid and blood to reach
target cells.
– Secreted by endocrine glands.
• Ex: Pituitary, Thyroid, etc.
Characteristics of Hormones
• Steroid hormones
– Formed from cholesterol
– Lipids
– Doesn’t use second messengers to transmit signal
to cell nucleus
– Examples: Sex hormones, such as testosterone
Hormones (cont.)
• Nonsteroid hormones
– Amines
• Derived from the amino acid thyrosine
• Ex: Epinephrine, Norepinephrine
– Protein
• Long chains of amino acids
• Ex: PTH
– Peptide
• Short chains of amino acids
• Ex: ADH
– Glycoproteins
• Proteins and carbohydrates
• Ex: FSH
Hormone Action
• Steroid
– Nonpolar, so are able to pass through cellular and
nuclear membranes
– Binds with receptors in the nucleus to activate the
hormone-receptor complex, that activates certain
sequences of DNA.
Hormone Action (cont.)
• Nonsteroid hormones
– Polar substances
– Make use of second messengers to relay message
• Most common is cAMP.
• Hormone → G-protein → Adenylate cyclase → cAMP
• cAMP activates protein kinases within the cytoplasm
Control Sources
• General method used is negative feedback
– Although, oxytocin uses positive feedback
• Three methods of signaling hormone release:
1. Tropic Hormones from the pituitary and
hypothalamus
2. Direct stimulation of the gland by the nervous
system
3. Direct response to the surrounding conditions
Pituitary Gland
• Attached to the base of the hypothalamus
• Anterior:
– Stimulated by tropic hormones from the
hypothalamus
– Hormones released include: GH, TSH, ACTH, FSH,
prolactin, LH
• Posterior:
– Stimulated by direct nervous pathways from the
hypothalamus
– Hormones released include: ADH and oxytocin
Thyroid Gland
• Located at the base of the throat
• Stimulated by both TSH (T3 and T4) and the
surrounding environment (calcitonin).
• Regulates metabolism
• Hormones secreted: T3, T4, calcitonin
Parathyroid Gland
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•
•
•
Located within the thyroid in patches
Stimulates osteoclasts
Hormones secreted: PTH
PTH is released with low blood calcium levels
– Releases calcium from bones into the blood
stream
– Antagonist to calcitonin
Adrenal Glands
• Located on top of the kidneys
• Cortex
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–
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–
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Outer layer of Adrenal glands
Stimulated by ACTH
Reacts to long-term stress
Releases glucose into the blood stream over time
Hormones released: aldosterone, cortisol
• Aldosterone acts in the renin-angiotensin system
• Medulla
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Inner section of adrenal glands
Stimulated by direct nervous connection to the brain
Responds to short term stress
Hormones released: epinephrine and norepinephrine
Pancreas
• Controls the glucose levels within the
bloodstream
• Has small groups within called the Islets of
Langerhans
– Contain two types of secreting cells:
• Alpha – releases glucagon
• Beta – releases insulin
Pineal Gland
• Located in the third ventricle of the brain
• Stimulated by the interpretation of light levels
outside the body
• Regulates the sleep/wake cycle of the body
• Hormones released: Melatonin
Thymus
• Posterior to the sternum and above the heart
• Largest in infants
• Regulates the development of white blood
cells, and facilitates the growth of T-cells.
• Release hormones called thymosins.
Gonads
• Ovaries
– Stimulated by LH and FSH
– Produces estrogen, progesterone
• Testes
– Produces testosterone
It sucks to get old 
• Hormone levels decrease with age
– GH production decreases dramatically
• Menopause is caused by lack of efficiency of
the ovaries
• Blood glucose regulation becomes very
inefficient.
Disorders of the Thyroid Gland
• Hyperthyroid
– Graves Disease: Low TSH level and high Thyroxin level,
autoimmune,
• Symptoms: irritation, bulging eyes (exophthalmia), feel
warm
• Hypothyroid
– Cretinism: developmental problems in infants, mental
retardation
– Goiters: lack of iodine in food supply, huge thyroid
gland
Disorders of the Adrenal Cortex
• Cushing Syndrome: too much ACTH
– Gain weight, moon face, thinning of hair,
weakness of limbs
• Addison’s Disease: not enough ACTH,
weakness, fatigue, anorexia, elevated red
blood cell count,
Diseases of Pancreas
Islets
• Diabetes I: inability to produce insulin,
autoimmune disorder in which immune
system attacks pancreatic beta cells
• Diabetes II: Excessive weight gain, cells lose
the ability to respond to insulin because
receptors are blocked