Endocrine System Overview.
Key Features of the Endocrine System
✓ Glands & target tissue
✓ Nervous system regulates physiological functions to maintain
homeostasis.
✓ Gland and target tissue are not structurally connected.
✓ “Ductless” = requires the circulatory system to work.
The Endocrine System
➢ Regulates long-term processes
× Growth × Development × Reproduction
➢ Uses chemical messengers to relay information and
instructions between cells
✓ Direct communication
✓ Paracrine communication
✓ Endocrine communication
Hormone Actions
➢ “Lock and Key” approach describes the interaction between
the hormone and its specific receptor.
✓ Receptors for nonsteroid hormones are located on the cell
membrane
✓ Receptors for steroid hormones are found in the
cell’s cytoplasm or in its nucleus
Key Features of the Endocrine System
➢ Hormones effect receptor sites in target tissues or organs.
➢ Specific receptor sites & specific response.
➢ “Lock and key”
✓ Hormones = key
✓ Target tissue or organ = lock.
➢ Function via a negative feedback system.
o Negative feedback loop is reaction that causes a decrease in function
, o Occur in response to stimulus. Often causes the output of a system
to be lessened, so the feedback tends to stabilize the system. Can be
referred to as homeostasis
Simple Negative Feedback System
Blood Sugars Elevate --Insulin Secreted--Glucose taken up by the cells--Blood
Sugars Decease
Action of the insulin causes the opposite condition that stimulated the insulin in
the first place.
Complex Negative Feedback System
➢ HYPOTHALMUS Either produces or releases inhibiting factors
✓ Hypothalamus- – Regulates almost all of the functions of
the Pituitary Gland – Secretes releasing hormones that tell
the pituitary gland to secrete its hormones.
✓ Located adjacent to pituitary gland
✓ Receives input from CNS
✓ Creates a circuit of influence on function and coordination of
the endocrine system and ANS
❖ CNS central nervous system Reaction to some sort of stimuli
Adrenal gland (homeostasis, life sustaining) AGSS
✓ Tent-shaped organs located at the top of each kidney.
✓ Two different parts with independent functions
• – Cortex- outer portion – Medulla- inner portion
✓ Maintains life-sustaining physiologic activities.
✓ Regulate kidney function, stress survivor, and regulate fight or flight
✓ Adrenal glands secrete hormones which help regulate
chemical balance, regulate metabolism, and supplement other
glands
✓ Secretes Catecholamine, Epi and Norepi
➢ Adrenal Gland (Cortex)
✓ Largest part of the adrenal gland
,✓ Adrenal cortex releases the following hormones =
Glucocorticoids, Mineralocorticoids, androgen (Testosterone and
estrogen)
✓ Adrenal Cortex
▪ Mineralocorticoids (Zona Glomerulosa)
• Aldosterone maintains electrolyte balance
✓ increased Na+ reabsorption by kidneys & increased K+ urinary loss ×
Glucocorticoids (Zona Fasciculate) ×Cortisol (Hydrocortisone):
×Stimulates gluconeogenesis ×Mobilization of free fatty acids
×Anti- inflammatory agent × Androgens (Zona Recticularis) × Bone
growth, muscle growth & blood formation
✓ Stores lipids, especially cholesterol and fatty acids
✓ ◆ Glucocorticoids (cortisol)
o Cortisol is the main hormone secrete
o Cortisol Feedback Mechanism
• SERUM Level of Cortisol Low/High trigger----
Secretes/Stops Secreting Corticotrophin-Releasing
Hormone (CRH) trigger------ANTERIOR PITUITARY
GLAND APG Releases/Stops Releasing
ACTH (adrenocorticotropic hormone)
trigger----ADRENAL CORTEX Secrete/Stops
Secreting Cortisol
• What affects the release of cortisol= ACTH
o Cortisol Affects the following
• Metabolism (carbohydrate, protein, and fat)
• Stress response
• Emotional stability
• Immune function
o Must be present for other physiologic processes to occur
▪ Catecholamine action
▪ Maintenance of normal excitability of
the myocardium
o Cortisol is Regulated by
, ▪ Negative feedback mechanism
▪ ACTH
o – Function of cortisol
▪ Maintain blood glucose level (Increases
hepatic gluconeogenesis and Inhibits
peripheral glucose use)
▪ Increases lipolysis, releasing glycerol and free
fatty acids
▪ Increases protein catabolism
o Degrades collagen and connective tissue
o Increases number of neutrophils released from the
bone marrow.
o Anti-inflammatory effect decreasing the migration
of inflammatory cells to sites of injury.
o Maintains behavior and cognitive functions.
o Sex Hormones
o
▪ Small amount of androgens and estrogens
in both genders
▪ Usually not significant
▪ In women is the major source of androgens.
▪ Adrenal insufficiency in women may
require testosterone replacement.
✓ Androgens
▪ Estrogens
▪ Testosterones
✓ Mineralocorticoids
▪ – Aldosterone
▪ – Rennin
o – Aldosterone
o Main one secreted
Key Features of the Endocrine System
✓ Glands & target tissue
✓ Nervous system regulates physiological functions to maintain
homeostasis.
✓ Gland and target tissue are not structurally connected.
✓ “Ductless” = requires the circulatory system to work.
The Endocrine System
➢ Regulates long-term processes
× Growth × Development × Reproduction
➢ Uses chemical messengers to relay information and
instructions between cells
✓ Direct communication
✓ Paracrine communication
✓ Endocrine communication
Hormone Actions
➢ “Lock and Key” approach describes the interaction between
the hormone and its specific receptor.
✓ Receptors for nonsteroid hormones are located on the cell
membrane
✓ Receptors for steroid hormones are found in the
cell’s cytoplasm or in its nucleus
Key Features of the Endocrine System
➢ Hormones effect receptor sites in target tissues or organs.
➢ Specific receptor sites & specific response.
➢ “Lock and key”
✓ Hormones = key
✓ Target tissue or organ = lock.
➢ Function via a negative feedback system.
o Negative feedback loop is reaction that causes a decrease in function
, o Occur in response to stimulus. Often causes the output of a system
to be lessened, so the feedback tends to stabilize the system. Can be
referred to as homeostasis
Simple Negative Feedback System
Blood Sugars Elevate --Insulin Secreted--Glucose taken up by the cells--Blood
Sugars Decease
Action of the insulin causes the opposite condition that stimulated the insulin in
the first place.
Complex Negative Feedback System
➢ HYPOTHALMUS Either produces or releases inhibiting factors
✓ Hypothalamus- – Regulates almost all of the functions of
the Pituitary Gland – Secretes releasing hormones that tell
the pituitary gland to secrete its hormones.
✓ Located adjacent to pituitary gland
✓ Receives input from CNS
✓ Creates a circuit of influence on function and coordination of
the endocrine system and ANS
❖ CNS central nervous system Reaction to some sort of stimuli
Adrenal gland (homeostasis, life sustaining) AGSS
✓ Tent-shaped organs located at the top of each kidney.
✓ Two different parts with independent functions
• – Cortex- outer portion – Medulla- inner portion
✓ Maintains life-sustaining physiologic activities.
✓ Regulate kidney function, stress survivor, and regulate fight or flight
✓ Adrenal glands secrete hormones which help regulate
chemical balance, regulate metabolism, and supplement other
glands
✓ Secretes Catecholamine, Epi and Norepi
➢ Adrenal Gland (Cortex)
✓ Largest part of the adrenal gland
,✓ Adrenal cortex releases the following hormones =
Glucocorticoids, Mineralocorticoids, androgen (Testosterone and
estrogen)
✓ Adrenal Cortex
▪ Mineralocorticoids (Zona Glomerulosa)
• Aldosterone maintains electrolyte balance
✓ increased Na+ reabsorption by kidneys & increased K+ urinary loss ×
Glucocorticoids (Zona Fasciculate) ×Cortisol (Hydrocortisone):
×Stimulates gluconeogenesis ×Mobilization of free fatty acids
×Anti- inflammatory agent × Androgens (Zona Recticularis) × Bone
growth, muscle growth & blood formation
✓ Stores lipids, especially cholesterol and fatty acids
✓ ◆ Glucocorticoids (cortisol)
o Cortisol is the main hormone secrete
o Cortisol Feedback Mechanism
• SERUM Level of Cortisol Low/High trigger----
Secretes/Stops Secreting Corticotrophin-Releasing
Hormone (CRH) trigger------ANTERIOR PITUITARY
GLAND APG Releases/Stops Releasing
ACTH (adrenocorticotropic hormone)
trigger----ADRENAL CORTEX Secrete/Stops
Secreting Cortisol
• What affects the release of cortisol= ACTH
o Cortisol Affects the following
• Metabolism (carbohydrate, protein, and fat)
• Stress response
• Emotional stability
• Immune function
o Must be present for other physiologic processes to occur
▪ Catecholamine action
▪ Maintenance of normal excitability of
the myocardium
o Cortisol is Regulated by
, ▪ Negative feedback mechanism
▪ ACTH
o – Function of cortisol
▪ Maintain blood glucose level (Increases
hepatic gluconeogenesis and Inhibits
peripheral glucose use)
▪ Increases lipolysis, releasing glycerol and free
fatty acids
▪ Increases protein catabolism
o Degrades collagen and connective tissue
o Increases number of neutrophils released from the
bone marrow.
o Anti-inflammatory effect decreasing the migration
of inflammatory cells to sites of injury.
o Maintains behavior and cognitive functions.
o Sex Hormones
o
▪ Small amount of androgens and estrogens
in both genders
▪ Usually not significant
▪ In women is the major source of androgens.
▪ Adrenal insufficiency in women may
require testosterone replacement.
✓ Androgens
▪ Estrogens
▪ Testosterones
✓ Mineralocorticoids
▪ – Aldosterone
▪ – Rennin
o – Aldosterone
o Main one secreted
