Endocrine system!!!!, Lecture notes of Anatomy

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ENDOCRINE SYSTEM

Part 2

RE GU LATIN G

BLO O D C ALCIU M

1. Hormones that increase Blood

[Calcium]

• Parathyroid hormone (PTH)
• Calcitriol (Vitamin D) Production

2. Hormone that decreases Blood

[Calcium]

• Calcitonin calium levels (^) - 1 -nice

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C ALCITRIOL PRODUCTION

• Ultraviolet light converts the precursor

molecule in keratinocytes to the inactive

vitamin D3 (cholecalciferol). Vitamin D3 also

is absorbed from the small intestine from

the diet.

• The inactive Vitamin D3 is converted to

calcidiol in the liver.

• As the inactive calcidiol is converted to the

active form , calcitriol in the kidney. PTH

increases the rate of this final reaction.

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DECREASING BLOOD CALCIUM

• Calcitonin is synthesized and released from the less numerous cells

of the thyroid gland call the parafollicular cells (c cells).

• The primary stimulus for calcitonin release from parafollicular cells

is a high blood calcium level.

• Calcitonin primarily inhibits osteoclast activity within bone and

stimulates the kidneys to increase the loss of calcium in the urine.

• The net effect of calcitonin is a reduction in blood calcium. promote ne formation get rid^ of^ excess^ calcium

RICKETS

• Rickets is a disease caused by a vitamin D deficiency in childhood.
• Patients with rickets acquire a bowlegged appearance as their weight increases and the bones in their lower limbs bend.
• During the Industrial Revolution, the incidence of rickets increased as children in cities were forced to work indoors in factories.
• Rickets continues to occur in some developing nations. The incidence recently has increased among urban U.S. children, who spend much of their time indoors and typically do not drink enough milk, opting instead for soft drinks.

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A NATOMY OF THE A DREN AL GLAN DS

• Adrenal (suprarenal) glands are paired,

pyramid-shaped endocrine glands on the

superior surface of each kidney

• Two regions constitute an adrenal gland:
  1. The adrenal cortex
  2. The adrenal medulla mighty closed ↑

AD RE NAL GLA ND

AN ATO M Y

• Adrenal Medulla
  • The adrenal medulla forms the inner core of each adrenal gland. It has extensive vascularization
  • Approximately 80% of the catecholamines released is epinephrine and about 20% is norepinephrine. Both hormones help reinforce the fight-or-flight response
• Adrenal Cortex
  • The adrenal cortex exhibits a distinctive yellow color because of the stored cellular lipids
  • The adrenal cortex is partitioned into three separate regions:
    • The outer zona G lomerulosa
    • The middle zona F asciculata
    • The inner zona R eticularis GFR G & R I

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HYPOTHA LA MI C- PI TUITARY- A DREN AL A XIS

• The release of cortisol is regulated through corticotropin-releasing hormone (CRH) from the hypothalamus
• Followed by the release of adrenocorticotropic hormone (ACTH) into general circulation from the anterior pituitary
• This physiologic tropic relationship is referred to as the hypothalamic-pituitary-adrenal axis.
• Cortisol accounts for 95% of the glucocorticoid activity
• Cortisol is transported within the blood by carrier proteins (corticosteroid-binding globulin [or CBG, also called transcortin] or albumin)
• The hypothalamic-pituitary-adrenal axis is regulated by negative feedback
• Therefore, increasing levels of cortisol inhibits both the release of CRH from the hypothalamus and ACTH from the AP verygood

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OTHER FAC TORS STIM ULATI NG C ORTI SOL RELEA SE

1. Time of Day - In a normal sleep-wake cycle, peak levels of cortisol correspond to the late stages of a normal sleep cycle (circadian rhythm) 2. Stress a) Both emotional stress (e.g., anxiety, anger, fear) and physical stress (e.g., fever, trauma, intense exercise) increase the release of cortisol b) The influence of chronic stress in triggering increased cortisol levels is the reason that cortisol has been given the nickname “the stress hormone” Stones-high calcium^ in^ kidneys^ cause^ Kidney^ stones to^ form (not all (^) kidney stones^ are bonce- (^) Osteoporosis , too much DTH (^) can chop up to^ much^ calcium^ based^ but^ most^ are bone (^) by activating moans-gut. Significant nausea^ ,^ lack^ of^ Osterclasts (^) /bone (^) mineral contraction (^) or too much (^) of the smooth density decreases) muscle in (^) your gut causes biggest^ concern^ is^ fractures take calcium^ and^ vitamin^ i^ supplement^ to (^) prevent it.^ but^ then arful nausea^ and^ gi issues resistant training^ is needed. bon needs to be (^) mechanicall groans

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CUSHING SYNDROME

• Cushing syndrome results from the chronic exposure of the body's tissues to excessive levels of cortisol (glucocorticoid) hormones
• This complex of symptoms is seen most frequently in people taking corticosteroids as therapy for autoimmune diseases such as rheumatoid arthritis, although some cases result when the adrenal gland produces too much of its own glucocorticoid hormones
• Corticosteroids are powerful immunosuppressant drugs, but they have serious side effects, such as osteoporosis, muscle weakness, redistribution of body fat, and salt retention
• Cushing syndrome is characterized by body obesity, especially in the face (called moon face) and back (buffalo hump). Other symptoms include hypertension, excess hair growth, kidney stones, and menstrual irregularities

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ADDISON DISEASE Addison Disease involves insufficient production of steroids (all three layers) from the entire adrenal cortex which can result from

1. Adrenal glands that were malformed during development
2. Impaired enzymatic pathways for steroid synthesis
3. Destruction of the adrenal gland by an autoimmune disorder

• The symptoms include weight loss, general fatigue and weakness, hypotension, and darkening of the skin. Perhaps the best-known person with Addison disease was John Fitzgerald Kennedy (JFK), 35th president of the United States opposite (^) of cushing. auto immune^ destruction^ of the adrenal (^) gland

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PANCREATIC HORMONES

• The primary endocrine function of the pancreas is to maintain the concentration of glucose in the blood.
• Chronically, high blood glucose levels ( hyperglycemia ) can be very damaging to blood vessels so this excess glucose must be transported into other body cells that can use or store this resource.
• Conversely, low blood glucose ( hypoglycemia ) levels result in lethargy, impairment of mental and physical function, and death if glucose levels drop too low.
• Thus, blood glucose levels must be closely regulated by 1. Insulin lowers blood glucose levels 2. Glucagon elevates blood glucose levels &

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IN SULIN REGU LATION

• Chemoreceptors in the beta cells of the pancreas detect an increase in blood glucose. Insulin can also be released through parasympathetic system stimulation.
• Beta cells release insulin, a protein hormone.
• The overall effect is a decrease in blood glucose, fatty acids, and amino acids. monito n te direct lette carg

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