What is the endocrine system?
a system that interacts with the nervous system to coordinate and integrate the activity of body cells
OVERVIEW OF ENDOCRINE SYSTEM
OVERVIEW OF ENDOCRINE SYSTEM
What are the two types of glands?
What is exocrine glands?
produce nonhormonal substances, such as sweat and saliva, and have ducts through which these substances are routed to a membrane surface
What is endocrine glands
produce hormones and lack ducts. they release their hormones to the surrounding tissue fluid
What does the endocrine gland include?
What is the definition of hormone
are long-distance chemical signals that travel in blood or lymph throughout the body.
What is autocrine?
are chemicals that exert their effect on the same cell that secretes them
What is paracrine?
also act locally but affect cell type other than those releasing the paracrine chemicals
What is hormone?
are chemical substances, secreted by cells into the extracellular fluid, that regulate the metabolic functions of other cells in the body
What are the two types of hormones?
1- amino acid based
What are the amino acid based hormones?
they are most hormones, molecular size vaies widely in this group.
What are the steroids based hormones?
they are synthesized from cholesterol.
Only gonadals and adrenocortical hormones are steroids
What are eicosanoids?
local hormones are biologically active lipids
What are some of the eicosanoids?
What do leukotrines do?
are signaling chemicals that mediate inflammation and some allergic reactions
What do prostaglandins do?
have multiple targets and effects, ranging from raising blood pressure and increasing the expulsive uterine contraction of birth to enhancing blood clotting, pain , and inflammation
What does a hormone do for the target cells?
1- alters plasma membrane permeability or membrane potential
2- stimulates synthesis of proteins or regulatory molecules such as enzymes within the cell
3- activates or deactivates enzymes
4- induces secretory activity
5- stimulates mitosis
What is Cyclic AMP?
Because most hormones cannot enter the cell membrane. they depend on an internal protein for the message to be deliver.
Cyclic AMP acts as a second messenger, so when a hormone binds to the exterior signals, a secondary messenger transmit the signal in the interior of the cell
How does the cyclic AMP signaling mechanism occurs?
1- the hormone, acting as the FIRST MESSENGER, binds to its receptor. This causes the receptor to change shape, allowing it to bind a nearby inactive G PROTEINS
2- the G PROTEIN is activated as the (GDP) bound to it is displaced by the high-energy compound GTP. The G protein behaves like a light switch, it is off when GDP is bound to it, and on when GTP is bound
3- The activated G protein moves along the plasma membrane and bind to and activates the effector enzyme ADENYLATE CYCLASE. at this point the GTP bound to the G protein is hydrolyzed to GDP and the G proteins becomes inactive again.
4- The activated Adenylate cyclase generates the second-messenger cAMP from ATP
5- cAMP, which is free to diffuse throughout the cell, triggers a cascade of chemical reaction in which one or more enzyme, called protein kinases, are activated.
Give the 1st step for cAMP?
- the first thing that happens is the binding of the hormone (first messenger) to the receptor in the outside of the cell.
The receptor which is a transmembrane proteins changes shape and allows the G proteins to bind with it
Give the 2nd step for cAMP?
- The G proteins is activated as the GDP bound to it is displace by GTP. The G protein behaves like a light switch, it is "off" when GDP is bound to it, and "on" when GTP is bound to it.
Give the me 3rd step for cAMP?
-The activated G protein moving along the plasma membrane binds to and activates the effector enzyme ADENYLATE CYCLASE,
The G proteins is hydrolyze to GDP and it is inactive one again.
What is the name of the enzyme effector in the cAMP process?
Give me the 4th step for cAMP?
The activated ADENYLATE CYCLASE generates the second messenger cAMP from ATP
give me the 5th step for cAMP?
cAMP, which is free to diffuse throughout the cell, triggers a cascade of chemical reactions in which one or more enzymes, called protein kinase, are activated.
The proteins kinase phosphorylates many other proteins
what type of inhibition does the cAMP does?
It activate and deactivates
What is PIP-calcium signal mechanisms?
Similar to cAMP, but intracellular calcium ions acts as the final mediator. Not cAMP
How does the PIP-calcium signal mechanisms works?
1- Hormone docking on the receptor causes it to bind the neary inactive G proteins
2- The G protein is activated as GTP binds, displacing GDP
3- The activated G protein then binds to and activates membrane-bound PHOSPHOLIPASE. the G protein then becomes inactive
4- phospholipase splits a plasma membrane phospholipid called PIP2, into DAG and IP3, and both these molecules act as second messenger
5- DAG activates specific proteins kinase, and IP3 trigger the release of Ca2+ from the endoplasmic reticulum and other intracellular storage site
6- The liberated Ca2+ takes on a second-messenger role, either by directly altering the activity of specific enzymes and plasma membrane Ca2+ channels or by binding to the intracellular regulatory proteins Calmodulin
What is on main different between amino-acid base hormone and steroid base hormones?
Steroid based hormones since they are lipid soluble they can enter the cell
Give the the 1 step for PIP
hormone docking on the receptor causes it to bind the nearby inactive G protein
Give the the 2 step for PIP
the G protein is activated as the GDP binds, is displace by GTP
Give the me 3 step for PIP
the activated G proteins then binds to and activates membrane-bound PHOSPHOLIPASE
he G proteins becomes inactivated
Give me the 4 step for PIP
Phospholipase splits a plasma membrane phospholipid called PIP2, into DAG and IP3 and both these molecules acts as second messenger
give me the 5 step for PIP
DAG activates specific proteins kinase, and IP3 trigger the release of Ca2+ from the endoplasmic reticulum and other intracellular storage site
give me the 6 step for PIP
the liberated Ca2+ takes on a second messenger role, either by directly altering the activity of specific enzyme and plasma Ca2+ channels or by binding to the intracellular regulatory protein Calmodulin.
Once Ca2+ binds to Calmodulin, enzymes are activated that amplify the cellular response.
What is up-regulation?
target cells form more receptors in response to rising blood levels of the specific hormones to which they respond
What is down-regulation?
prolonged exposure to high hormone concentration desensitizes the target cells, so that they respond less vigorously to hormonal stimulation.
This involves the loss of receptors and prevents the target cell from overreacting to persistently high hormone levels
What are the two ways hormones circulates the body in blood?
Bound to a proteins carrier.
What are the typical hormones that travel the body bound to a carrier?
lipid soluble hormones
How are most hormones removed from the body?
some hormones are rapidly degraded by enzymes in their target cells, but most are removed form the blood by the kidneys or liver.
What is the half-life or a hormones?
a few minutes to 30 minutes.
Water soluble hormones are the have the shortest half life
what is the shortest acting hormones?
Those that are lipid soluble
What are the main types of interaction between the hormone and the target cell?
What is the permissiveness action of hormones in the target cells?
is the situation when one hormone cannot exert its full effect without another hormone being present.
the development of the reproductive system is largely regulated by reproductive system hormone. however thyroid hormone is necessary for normal timely development of reproductive structure
What is the synergism action of hormone in the target cells?
this situation occurs where more than one hormone produces the same effects at the target cell and their combined effects are amplified.
Glucagon and epinephrine cause the liver to release glucose to the blood; when they act together, the amount of glucose release is about 150% of what is release when each hormone act alone
What is the antagonism action of hormone in the target cell
in this situation, one hormone opposes the action of another hormone
insulin, which lowers blood sugar level, is antagonized by the action of glucagon, which acts to raise blood sugar levels.
What are humoral stimulations of endocrine glands?
soem endocrine glands secrete their hormones in direct response to changing blood levels of certain ions and nutrient.
What is the neural stimulation of endocrine glands?
nerve fibers stimulate hormone release
What is the hormonal stimulation of endocrine glands?
many endocrine glands release their hormones in response to hormones produced by other endocrine organdies, and the stimuli in these cases are called hormonal stimuli
THE PITUITARY GLAND (HYPOPHYSIS)
THE PITUITARY GLAND (HYPOPHYSIS)
Where is the pituitary gland located?
In the sella turcica in the sphenoid bone
What are the major lobes of the pituitary gland?
the neural tissue, posterior pituitary love
the glandular, anterior pituitary lobe
What is the posterior pituitary lobe?
is composed largely of pituicytes, and nerve fibers
It release neurohormones, hormones secreted by neurons, received ready made from the hypothalamus.
Thus this love is a hormone storage area and not a true endocrine gland.
What is the anterior pituitary lobe?
is composed of glandular tissue, and it manufactures and release a number of hormones
What are the six types of hormones that the anterior pituitary gland releases?
- growth hormone (GH)
- thyroid-stimulating hormone (TSH)
-adrenocorticotropic hormone (ACTH)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin (PRL)
What type of secondary messenger do all of the anterior pituitary gland hormone use?
They all use the cAMP second-messenger system
Who controls the anterior pituitary gland?
Tell me about growth hormone. Major function, effect, regulation
-although GH stimulates most body cells to increase in size and divide, its major target are the bones and skeletal muscles. Stimulation of the epiphyseal plate leads to the long bone growth, stimulation of skeletal muscle promotes increased muscle mass
-GH is essentially an anabolic hormone, GH promotes protein synthesis and it encourage the use of fats for fuel, thus conserving glucose.
- GH mobilizes fats from fat deposits for transpire t to cell, increasing blood levels of fatty acids. It also decreases the rate of glucose uptake and metabolism.
-In the liver, it encourages glycogen breakdown and release of glucose to the blood
- Secretion of GH is regulated by Growth hormone-releasing hormone (GHRH)
-Inhibition of GH is regulated by Growth Hormone-inhibiting hormone (GHIH)
What is the main job and target of Growth hormone?
The GH main job is the anabolism effect on skeletal muscle and bone. It causes them to increase in size
The GH, stimulates the epiphyseal plate on long bones which lead them to growth, and the stimulation of skeletal muscle promoting them to increase muscle mass
What is the effects of GH in fats?
The way that GH promotes Growth is by the use of fats for fuel and promoting protein synthesis.
GH mobilizes fats from far depots for transport cells, increasing blood levels of fatty acids. It also decreases the rate of glucose uptake and metabolism
What is the effect of GH in the liver?
In the liver GH encourages glycogen breakdown and release of glucose to the blood.
What is the name of the GH inhibitor?
Growth hormone-inhibiting hormone GHIH
What is the name of the GH stimulant?
Growth hormone-releasing hormone GHRH
What is GHIH?
Growth hormone inhibiting hormone
What is GHRH?
Growth hormone releasing hormone
Where do GHIH and GHRH come from?
They are made in the hypothalamus
When is the highest time of release of GH?
During the night
What does hyper-secretiong of GH leads to?
What does hypo secreting of GH leads to?
Tell me about Thyroid-stimulating hormone?
or thyrotropin, is a tropic hormone that stimulates normal development and secreting activity of the thyroid gland.
What are tropic hormones?
hormones that regulate the secretory action of other endocrine glands
What hormone and who produces regulates the thyroid-stimulating hormone?
Thyrotropin-releasing hormone (TRH), which is produce by the hypothalamus, and stimulates the secreting of thyroid-stimulating hormone.
What is the antagonistic hormone for thyroid-stimulating hormone?
The secreting of thyroid-stimulating hormone acts on both the thyroid and the hypothalamus, in the hypothalamus this inhibit the release of TSH( Thyrotropin-relasing hormone) which stop the release of thyroid hormone.
The hypothalamus also release GHIH which also reinforces the blockade of TSH release
tell me about adrenocorticotropic hormone?
Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex to release corticosteroid hormones, most importantly glucocorticoids that help the body to resist stressors.
What stimulates the release of ACTH?
ACTH is stimulated by hypothalamic corticotropin-releasing hormone (CRH)
What inhibit the release of ACTH?
ACTH is inhibited by the rising levels of glucocorticoids (product of the adrenal gland cortex being stimulated by ACTH) which blocks secreting of CRH in the hypothalamus. which consequently stops the pro ducting of ACTH
Tell me about Gonadotropins?
Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH) referred to collectively as gonadotropins. they regulate the functions of the gonads (ovaries and testes)
What does FSH and LH do in both sexes?
-FSH stimulates gamete production
-LH promotes production of gonadal hormons
What does LH and FSH do in females?
In females LH works with FSH to cause maturation of an egg-containing ovarian follicle
LF, triggers ovulation and promotes synthesis and release of ovarian hormone
What does LH and FSH do in males?
LH stimulates the interstitial cell of the testes to produce the male hormone testosterone
Which hormone stimulate the release of gonadotropin?
Gonadotropin-releasing hormone GnRH) stimulates the release of gonadotropin by the hypothalamus.
Which hormone inhibit the release of gonadotropin?
Gonadal hormones produced in response to gonadotropins, feed back to suppress FSH and LH release
Tell me about Prolactin?
Prolactin (PRL) stimulates the production of milk by the breasts
What is the stimulating hormone for prolactin?
Prolactin-releasing hormone (PRH) controlled by the hypothalamus
What is the inhibitory hormone for prolactin
Prolactin-Inhibiting hormone (PIH), which is the neurotransmitter dopamine, prevents prolactin secretion
What physiological levels affecting the females stimulates prolactin
low estrogen levels stimulates PIH release, therefore not much prolactin being produce
High estrogen levels promotes the release of PRH thus prolactin level in creases
What are the posterior pituitary hormones?
- antidiuretic hormone (ADH)
Where do the posterior pituitary hormones come from?
They come from the hypothalamus, hence the posterior pituitary gland functions as a storage unit. And when they are needed they are release on demand by the hypothalamus.
What type of second messenger mechanisms do the hormones in the posterior pituitary gland use?
Oxytocin and ADH use the PIP-calcium second messenger mechanism.
Tell me about oxytocin?
Its a strong stimulant of uterine contraction, Oxytocin is released in significantly higher amounts during childbirth.
Oxytocin stimulates contraction of smooth muscle, particularly that of uterus and breasts
What changes in the peaks of pregnancy and oxytocin?
The numbers of oxytocin receptors in the uterus peaks near the end of pregnancy, and uterine smooth muscle becomes more and more sensitive to the hormones stimulatory effects.
Stretching of the uterus and cervix as birth nears dispatches afferent impulses to the hypothalamus, whis responds by synthesizing oxytocin and triggering its release.
What is the function of oxytocin?
it acts on the smooth muscle of the uterus and does the childbirth
In the breasts oxytocin acts as the hormonal trigger for milk ejection, in when whose breasts are producing milk in response to prolactin
What type of feedback mechanism does oxytocin exhibits?
Positive feedback mechanisms
Tell me about Antidiuretic hormone?
ADH, prevents wide swans in water balance, helping the body avoid dehydration and water overload. Thus inhibits or prevent urine formation and water loss in the body
What is diuretic
What is antidiuretic
inhibition of urine production
How is the hypothalamus stimulated to produce ADH?
hypothalamic neurons, called OSMORECEPTORS, continually monitor the solute concentration of the blood.
When solute threaten to become too concentrated, the osmoreceptors transmit excitatory impulses to the hypothalamic neurons in which stimulates the synthesize and release of ADH
What does ADH targets?
ADH targets the kidney tubules. the tubule cells respond by reabsorbing more water form the forming urine and returning it to the bloodstream. As a result, less urine is produced and blood volume is increase
What does inhibit ADH?
drinking alcoholic beverage inhibit ADH secreting and causes copious urine output. Also drinking large amount of water.
What is ADH use for in patients?
ADH is used to manage hypertension and the edema (water retention in tissue) typical of congestive heart failure.
Conclusion, hormones produce in the pituitary gland
Anterior pituitary gland
- Growth hormone (GH)
- Thyroid-Stimulating hormone (TSH)
- Adrenocorticotropic hormone (ACTH)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin (PRL)
Posterior pituitary gland
- Antidiuretic hormone (ADH)
What is GH?
What is TSH?
What is ACTH?
What is FSH?
What is LH?
What is PRL?
What is ADH?
Which hormone targets the liver, muscle, bone, cartilage and other tissues. Anabolic hormone, stimulates somatic growth, mobilizes fats, spares glucose?
Which hormone targets thyroid gland; stimulates thyroid gland to release thyroid hormone?
Which hormone target the adrenal cortex, promotes release of glucocorticoids and androgens?
Which hormone targets the ovaries and testes; in females, stimulates ovarian follicle maturation and estrogen production, in males stimulates sperm production?
Which hormone targets ovaries and testes, in female, triggers ovulation and stimulates ovarian production of estrogen and progesterone, in males, promotes testosterone production?
Which hormone targets great secretory tissue, promotes lactation?
Which hormone stimulates uterus, stimulates uterine contraction, initiates labor, breast milk ejection?
Which hormone targets the kidneys, stimulates kidney tubule cells to reabsorbs water?
What are the hormone produced by the posterior and anterior pituitary gland?
- Growth hormone
- thyroid-stimulating hormone
- adrenocorticotropic hormone
- luteinizing hormone
- follicle-stimulating hormone
- melanocyte-stimulating hormone
- Antidiuretic hormone
What are the direct hormones in the anterior pituitary?
- Growth hormone
What are the tropic hormone in the anterior pituitary?
- adrenocorticotropic hormones
- thyroid-stimulating hormone
- luteinizing hormone
- follicle stimulating hormone
- melanocytes stimulating hormone
What are the hormone being produce by the thyroid gland?
Thyroid hormone, which is actually 3 hormones
- thyroxine T4
- triiodothyronine T3
Which of the two hormones is the major production of thyroid gland?
T4, thyroxine, is the major hormone secreted by the thyroid follicles.
Most of T3 is formed at the target tissues by conversion of T4 to T3
What are the target organs and tissue for the thyroid gland hormones?
except for the adult brain, spleen, testes, uterus, and the thyroid gland itself, TH effects virtually every cell in the body
What is the calorigenic effect of the thyroid gland?
by stimulating enzyme concerned with glucose oxidation, it increases basal metabolic rate and body heat production
What is another function of the thyroid gland?
because TH provokes an increase in the number of adrenergic receptors in blood vessels, it plays an important role in maintaining blood pressure.
TH is important regulator of tissue growth and development. It is especially critical for normal skeletal and nervous development and maturation and for reproductive capabilities
Synthesis of TH
How do TH move in the body?
Most released T4 and T3 immediately bind to transport proteins, most importantly TBGs produced by the liver
What proteins allows for TH transport?
TBGs, which are produced by the liver
Which is more active, T3 or T4?
both T4 and T3 bind to target tissues receptors, but T3 binds much more avidly and is about ten times more active.
Also, most peripheral tissues have the enzymes needed to convert T4 to T3, a process that entails enzymatic removal of one iodine group.
How is the T4 stimulated?
falling blood levels trigger the release of TSH, and ultimately stimulating of T4
How is T4 inhibited?
Rising levels of T4 feed back to inhabit the hypothalamus, temporarily shutting off the stimulus for TSH
Tell me about Calcitonin?
produced by thyroid gland The C cell produce it, its most important effect is to lower blood Ca2+ levels,
How does Calcitonin targets skeleton?
1- inhibit osteoclast activity and hence bone resorption and release of Ca2+ from the bony matrix
2- stimulates Ca2+ uptake and incorporation into bone matrix
What inhibit and stimulates the production of Calcitonin
Excessive blood levels of Ca2+ act as a humoral stimulus for Calcitonin release, whereas declining blood Ca2+ levels inhibit C cell secretory activity
TH normal effect on Basal metabolic rate, temperature regulation
-promotes normal oxygen use and BMR, calorigenesis,
-enhances effect of sympathetic nervous system
TH normal effect on carbohydrate/lipids/protein metabolism?
-Promotes glucose catabolism
-essential for protein synthesis
-enhances liver synthesis of cholesterol
TH normal effect on nervous system?
-promotes normal development of nervous system in fetus and infant
-promotes normal adult nervous system function
TH normal effect on Cardiovascular system?
- promotes normal functioning of the heart
TH normal effect on muscular system
promotes normal muscular development and fuction
TH normal effect on skeletal system?
promotes normal growth and maturation of the skeleton
TH normal effect on Gastrointestinal system
-promotes normal GI motility and tone
- increases secretion of digestive juices
TH normal effect on reproductive system
- promotes normal female reproductive ability and lactation
TH normal effect on integumentary system?
- promotes normal hydration and secretory activity of skin
TH hyposecretion effect on Basal metabolic rate (BMR)/ temperature regulation?
- BMR below normal
- Decreased body temperature and cold intolerance
- Decreased appetite
- Weight gain
- reduced sensitivity to catecholamines
TH hyposecretion effect on carbohydrates/lipids/proteins/metabolism?
- decreased glucose metabolism
- Elevated cholesterol/triglyceride levels in blood
- decrease protein synthesis
TH hyposecretion effect on nervous system?
-in infant, slowed/deficient brain development, retardation
- in adults, mental dulling, depression, parasthesias, memory impairment, hypoactive reflex
TH hyposecretion effect on cardiovascular system?
- deccreased efficiency of pumping action of the heart
- low heart rate and blood pressure
TH hyposecretion effect on muscular system?
sluggish muscle action
TH hyposecretion effect on skeletal system
- in child, growth retardation, skeletal stunning and retention of childs body proportion
- in adults, join pains
TH hyposecretion effect on Gastrointestinal system?
-depressed GI motility, tone, and secretory activity
TH hyposecretion effect on reproductive system
- depressed ovarian function
TH hyposecretion effect on integumentary system
- skin pale, think and dry
hair coarse and thick
TH hypersecretion effects on Basal metabolic rate (BMR)/ temperature regulation
- BMR above normal
- increase body temperature and heat intolerance
- Increased sensitivity to catehcolamines may lead to high blood pressure
TH hypersecretion effects on carbohydrates/lipids/proteins metabolism
enhanced catabolism of glucose, proteins and fats
loss of muscle mass
TH hypersecretion effects on nervous system?
irritability restlessness insomnia, exophthalmos personality change
TH hypersecretion effects on cardiovascular system?
-rapid heart rate and possible palpitations
- high blood pressure
-heart failure if prolonged
TH hypersecretion effects on muscular system
muscle atrophy and weakness
TH hypersecretion effects on skeletal system
in child, excessive skeletal growth initially, follow by early epiphyseal closure and short stature
in adults demineralization of skeleton
TH hypersecretion effects on gastrointestinal system
excessive GI motility
loss of appetite
TH hypersecretion effects on reproductive system
in females, depresse ovarian function
in males, impotence
TH hypersecretion effects on integumentary system?
skin flushed, thin and moist
hair fine and soft
nails soft and thin
THE PARATHYROID GLAND
THE PARATHYROID GLAND
what is the parathyroid gland?
a tiny, yellow-brown gland which are found in the posterior aspect of the thyroid gland.
The chief cells found in the parathyroid gland produce PTH, or parathyroid hormone
What does parathyroid hormone do?
PTH the protein hormone of these glands, is the single most important hormone controlling the calcium balance of the blood
Which is the most important hormone for controlling blood Ca2+ level?
Parathyroid hormone PTH
How is PTH trigger?, what inhibits it?
PTH is release by falling blood Ca2+ levels and inhibited by hypercalcemia.
PTH increases Ca2+ levels in blood stimulating three targets organs
- The Skeleton
How does PTH affect the skeleton system?
PTH release, stimulates osteoclast (bone resorbing cells) to digest some of the bony matrix and release ionic calcium and phosphate to the blood
How does PTH affect the kidneys?
Enhances reabsorption of Ca2+ and excretion of PO4 by the kidneys.
It also stimulated the transformation of Vitamin D to Calcitriol which aid in the reabsorption of Calcium in the intestines.
How does PTH affect the intestines?
Increase absorption of Ca2+ by the intestinal mucosal cells.
Calcium absorption by the intestine is enhanced indirectly by PTH effect on vitamin D activation. Vitamin D is required for absorption of Ca2+ from ingested food, but the form in which vitamin is ingested or produced by the skin is relatively inactive. For Vitamin D to exert its physiological effects, it must first be converted by the kidneys to its active vitamin D3 form CALCITRIOL, which is a transformation stimulated by PTH
THE ADRENAL GLAND
THE ADRENAL GLAND
What is the adrenal gland?
A pair, each adrenal gland is perched atop of the kidneys, where they are enclosed in a fibrous capsule and a cushion of fat.
there are two adrenal glands.
What is the adrenal medulla?
Its more of nervous tissue than a gland, it part of the sympathetic nervous system
What is the adrenal cortex?
encapsulating the medullary region and forming the bulk of the gland, is glandular tissue derived from embryonic mesoderm.
Which is more superficial?
The outer adrenal cortex cover the The inner adrenal medulla
Tell me about the adrenal cortex?
adrenal cortex produces corticosteroid, which are hormones made from steroid. they are synthesis in the adrenal cortex.
What is a difference between amino base hormones and steroid base hormones?
unlike the amino acid based hormones, steroid hormones are not stored in cells.
Therefore, their rate of release in response to stimulation depends on their rate of synthesis
What are the three types of corticosteroid made in the adrenal cortex?
Tell me about the mineralocorticoids, essential function.
the essential function of mineralocorticoids is regulation of the electrolytes concentration in extracellular fluids, particular of Na+ and K+
What is the most abundant cation in extracellular fluid?
What is the most important mineralocorticoids?
Aldosterone, account for more than 95% of the mineralocorticoids produced.
Tell me about aldosterone?
Produce by the adrenal cortex, its a mineralocorticoid, its most important job is to maintain a Na ion balance, which is performs by stimulating transcription of the Na+, K+ ATPse, the sodium pump that exchanges K+ for Na+
It reduces excretion of Na+ from the body
What does Aldosterone do?
Aldosterone reduces excretion of Na+ from the body.
Its target is the distal parts of the kidney tubules, where it stimulate Na+ reabsorption from the forming urine and its return to the blood-stream.
Aldosterone effects on the renal tubules causes sodium and water retention accompanied by elimination of K+
How does aldosterone stimulated?
Aldosterone secretion is stimulated by rising blood levels of K+, low blood levels of Na+, and decreasing blood volume and blood pressure.
What inhibits aldosterone secretion?
Aldosterone secretion is inhibited by low K+ level, high blood levels of Na+, and increasing blood volume and blood pressure
What are the four mechanisms that regulate aldosterone secretion?
1- the renin-angotensis mechanism
2- plasma concentration of Sodium and Potassium
4- Atrial natriuretic peptide (ANP)
What is the rein-angotensis mechanism?
The renin-angiotensis mechanism is the major regulator of aldosterone release, influxes both the electrolyte0water balance of the blood and the blood pressure
Specialized cells in the kidney become excited when blood pressure/volume declines or plasma osmolarity drops.
These cells respond by releasing RENIN into the blood. Renin cleaves off part of the plasma protein ANGIOTENSINOGEN triggering an enzymatic cascade
leading to the formation of ANGIOTENSIN II, a potent
stimulator of aldosterone release by the adrenal cortex.
What is a potent stimulator of aldosterone?
How does the plasma concentration of sodium and potassium? contribute to the formation of aldosterone
fluctuating blood levels of Na+ and K+ directly influence the zone glomerulosa cells. Increased K+ and decreased Na+ are stimulatory, the opposite conditions are inhibitory
How does ACTH stimulates aldosterone?
Under normal circumstances, ACTH released by the anterior pituitary gland has little or no effect on aldosterone release.
However when a person is severely stressed, the hypothalamus secures more CORTICOTROPIN-RELEASING HORMONE and the rise in ACTH blood levels that follows step up the rate of aldosterone secretion to a small extent.
How does atrial natriuretic peptide (ANP) stimulate aldosterone?
atrail natriuretic peptide, a hormone secreted by the heart when blood pressure rises, fine tunes blood pressure and sodium water balance of the body.
Its major effect is to inhibit the renin-angiotensis mechanism.
It blocks renin and aldosterone secretion and inhibit other angiotensin,induced mechanisms that enhances water and Na+ reabsorption
What are glucocorticoids?
Are absolutely essential to life, the glucocorticoids influence the energy metabolism of most body cells and help us resist stressors.
Under normal circumstances, they help the body adapt to intermittent food take by keeping blood sugar levels fairly constant and maintaing blood volume by preventing the shift of water into tissue cells.
What is an example of a glucocorticoid hormone?
What is cortisol? functions
cortisol release is promoted by ACTH, triggered in turn by the hypothalamic releasing hormone CRH.
Cortisol secretory burst, driven by patterns of eating and activity, occur in a definite pattern throughout the day and night
Cortisol, prime metabolic effect is to provoke GLUCONEOGENESIS, which is the formation of glucose from fats and proteins.
What else does cortisol do?
cortisol enhances epinephrine vasoconstrictive effects, and the rise in blood pressure and circulatory efficiency that results helps ensure that these nutrients are quickly distributed to the cells.
What happens when you have excessive levels of glucocorticoids?
1- depress cartilage and bone formation
2- inhibit inflammation by stabilizing lysosomal membrane and preventing vasodilation
3- depress the immune system
4- promote changes in cardiovascular, neural, and gastrointestinal functions
What are gonadocorticoids?
They are sex hormones.
The bulk of gonadocorticoids secreted by the adrenal cortex are weak androgens, or male sex hormones
What type of hormone do gonadocorticoids contains
What does the androgen do?
Androgens are weak sex hormones, they are converted into testosterones which are more strong sex hormones.
or to estrogens in females
its the contribution of the adrenal cortex to of gonadocorticoids important
the amount of gonadocorticoids produce by the adrenal cortex is insignificant compared with the amount made by the gonads during late puberty and adulthood
Tell me about the adrenal medulla?
go back to chap 14
What is the pancreas?
Located artily behind the stomach in the abdomen, the pancreas is a mixed gland composed of both endocrine and exocrine gland cells.
What is the name of the cells that produce hormone in the pancreas?
The islets contains two major population of hormone producing cells, Alpha cells and the Beta cells
What do alpha cells produce?
Alpha cells in the pancreatic islet produce glucagon
What do the beta cells produce?
The beta cells in the pancreatic islet produce insulin..
There are more beta cells than alpha cells
What is particularly important about the alpha and beta cells?
These cells act as tiny fuel sensors, secreting glucagon and insulin appropriately during the fasting and fed state
What is insulin?
Its a hypoglycemic hormone
What is glucagon?
Its a hyperglycemic hormone
Tell me about glucagon?
is an extremely potent HYPERGLYCEMIC agent.
-One molecule of glucagon can cause the release of 100 million molecules of glucose into the blood
What is the major target of glucagon?
The liver is the major target of the glucagon
it affect the liver by
1- breakdown of glycogen to glucose (glycogenolysis)
2- synthesis of glucose from lactic acid and from noncarbohydrate molecules (gluconeogenesis)
3- release of glucose to the blood by liver cells, which cause blood sugar levels to rise
What is glycogenolysis?
its the breakdown go glycogen to glucose
What is gluconeogenesis?
its the synthesis of glucose from lactic acid and from noncarbohydrate molecules
What is a potent hyperglycemic?
How is glucagon endured to be realized? What is a suppressor?
secretion of glucagon by the alpha cells is prompted by humoral stimuli, mainly falling blood sugar levels.
However, sympathetic nervous system stimulation and rising amino acid levels are also stimulatory glucagon.
Glucagon release is suppressed by rising blood sugar levels and somatostatin
Tell me about insulin?
its a synthesized as part of a larger polypeptide chain called PROINSULIN
What are insulins effect?
Insulins effect are most obvious when we had just eaten.
Its main effect is to lower blood sugar levels, but it also influce protein and fat metabolism.
Circulating insulin lower blood sugar level by enhancing membrane transport of glucose into body cells, especially muscle and fat cells.
What doesn't insulin do?
It doesn't accelerate glucose entry into liver, kidney and brain tissue, all of which have easy access to blood glucose regardless of insulin level
What does insulin inhibits
Insulin inhibits the breakdown of glycogen to glucose (glycogenolysis) and the conversion of amino acids or other non carbohydrates into glucose (gluconeogenesis), thus it counters any metabolic activity that would increase plasma levels of glucose.
What are the things that insulin do after glucose enters the target cell?
1- catalyze the oxidation of glucose for ATP production
2- joins glucose molecule together to form glycogen
3- converts glucose to fat
So the rule is as follow, energy needs are met first, followed by glycogen formation, finally glucose is converted into fat
What stimulates pancreatic beta cells?
-Pancreatic beta cells, are stimulated to secrete insulin chiefly by elevated blood sugar levels,
-rising plasma levels of amino acids and fatty acids
-release of acetylcholine by parasympathetic nerve fibers
What is a difference between the gonads and the adrenal cortex?
the male and female gonands produce steroid sex hormones, identical to those produced by adrenal cortical cells.
The major distinction is the source and relative amounts produced.
besides producing ova and eggs, the ovaries produce several hormones, most importantly estrogens and progesterone
What is estrogens?
Estrogens are responsible for maturation of the reproductive organs and the appearance of the secondary sex characteristic of female at puberty.
produce sperm, and the sex hormone testosterone.
What does testosterone do?
Testosterone during puberty, initiates the maturation of the male reproductive organs and the appearance of secondary sex characteristic and sex drive.
In addition, testosterone is necessary for normal sperm production and maintains the reproductive organs in their mature functional state in adult males.
What stimulates the release of gonadal mormon?
THE PINEAL GLAND
THE PINEAL GLAND
What is the main function of the pineal gland?
Its main hormonal contribution is the production of melatonin
what is the major contribution of the thymus?
the major hormonal contribution is thymopoietin, thymic factor, and thymosins.
They all play an important normal development of T lymphocytes and in the immune response
OTHER HORMONE PRODUCING STRUCTURE
OTHER HORMONE PRODUCING STRUCTURE
hormone = Gastrin
trigger = secreted in response to food
stomach: stimulates glands to release hydrochloric acid HCL
Stomach, not gastrin
hormone = serotonin
trigger = secreted in response to food
stomach; causes contraction of stomach muscle
Duodenum of small intestine
Hormone = intestinal gastrin
trigger = secreted in response to food, especially fats
stomach: inhibit HCL secretion and gastrointestinal tract mobility
Duodenum, not intestinal gastrin
hormone = secretin
trigger = secreted in response to food
pancreas and liver: stimulates release of bicarbonate-rich juice
Stomach: inhibits secretory activity
Duodenum, not secretin or intestinal gastrin
hormone = cholecystokinin CCK
trigger = secreted in réponse to food
Pancreas: stimulates release of enzyme-rich juices
Gallbladder: Stimulates expulsion of stored bile
Sphincter of oddi: causes sphincter to relax, allowing bile and pancreatic juices to enter duodenun
hormone = erythropoietin
trigger = hypoxia blood
bone marrow" stimulates production of red blood cell
hormone = cholecalciferol
trigger = cholecalciferol activated by the kidneys to activate vitamin D and release in response to parathyroid hormone
intestine: stimulates active transport of dietary calcium across intestinal cells membrane
hormone = atril natriuretic peptide
trigger = secreted in response to stretching of atria (rise blood pressure)
kidneys: inhibits sodium ion reabsorption and renin release
adrenal cortex: inhibit secretion of aldosterone, decrease blood pressure
hormone = leptin
trigger = secreted in response to fatty food
brain: suppresses appetite, increases energy expenditure
Adipose tissue, not leptin
hormone = resistin
trigger = secreted in response to fatty foods
fat, muscle, liver: antagonize insulins action on fat, muscle and liver cells