Parathyroid Hormones Calcitonin (Thyrocalcitonin) is made by the parafollicular (C-cells) of the...
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Parathyroid Hormones Calcitonin (Thyrocalcitonin) is made by the parafollicular (C-cells) of the thyroid gland and when secreted lowers the blood calcium
Parathyroid Hormones Calcitonin (Thyrocalcitonin) is made by
the parafollicular (C-cells) of the thyroid gland and when secreted
lowers the blood calcium level An increase in blood calcium will
stimulate the C-cells of the thyroid to secrete calcitonin
Increased calcitonin will cause a negative feedback inhibition of
parathyroid hormone (PTH) which causes a decrease in blood calcium
and an increase in blood phosphate levels
Slide 2
PARATHYROID HORMONES (Interactions Animation) Calcitonin You
must be connected to the internet to run this animation
Slide 3
Parathyroid hormone (PTH) is made by the more numerous chief
(principal) cells of the gland PTH increases absorption of Ca 2+
from the GI tract and stimulates osteoclastic activity so that Ca
2+ is released from bone into the blood Parathyroid Hormones
Slide 4
PARATHYROID HORMONES (Interactions Animation) Parathyroid
Hormone You must be connected to the internet to run this
animation
Slide 5
1 High level of Ca 2+ in blood stimulates thyroid gland
parafollicular cells to release more CT. 1 High level of Ca 2+ in
blood stimulates thyroid gland parafollicular cells to release more
CT. CALCITONIN inhibits osteoclasts, thus decreasing blood Ca 2+
level. 2 1 High level of Ca 2+ in blood stimulates thyroid gland
parafollicular cells to release more CT. Low level of Ca 2+ in
blood stimulates parathyroid gland chief cells to release more PTH.
CALCITONIN inhibits osteoclasts, thus decreasing blood Ca 2+ level.
3 2 1 High level of Ca 2+ in blood stimulates thyroid gland
parafollicular cells to release more CT. Low level of Ca 2+ in
blood stimulates parathyroid gland chief cells to release more PTH.
CALCITONIN inhibits osteoclasts, thus decreasing blood Ca 2+ level.
PARATHYROID HORMONE (PTH) promotes release of Ca 2+ from bone
extracellular matrix into blood and slows loss of Ca 2+ in urine,
thus increasing blood Ca 2+ level. 3 42 1 PTH also stimulates the
kidneys to release CALCITRIOL. High level of Ca 2+ in blood
stimulates thyroid gland parafollicular cells to release more CT.
Low level of Ca 2+ in blood stimulates parathyroid gland chief
cells to release more PTH. CALCITONIN inhibits osteoclasts, thus
decreasing blood Ca 2+ level. PARATHYROID HORMONE (PTH) promotes
release of Ca 2+ from bone extracellular matrix into blood and
slows loss of Ca 2+ in urine, thus increasing blood Ca 2+ level. 3
42 5 1 CALCITRIOL stimulates increased absorption of Ca 2+ from
foods, which increases blood Ca 2+ level. PTH also stimulates the
kidneys to release CALCITRIOL. High level of Ca 2+ in blood
stimulates thyroid gland parafollicular cells to release more CT.
Low level of Ca 2+ in blood stimulates parathyroid gland chief
cells to release more PTH. CALCITONIN inhibits osteoclasts, thus
decreasing blood Ca 2+ level. PARATHYROID HORMONE (PTH) promotes
release of Ca 2+ from bone extracellular matrix into blood and
slows loss of Ca 2+ in urine, thus increasing blood Ca 2+ level. 3
42 5 6 Calcium Regulation
Slide 6
The Adrenal Glands There are two adrenal glands, one superior
to each kidney (also called the suprarenal glands). During
embryonic development, the adrenal glands differentiate into two
structurally and functionally distinct regions the adrenal cortex
the adrenal medulla Catecholamines like norepinephrine Steroid
hormones like cortisol
Slide 7
The Adrenal Glands
Slide 8
The Adrenal Cortex The adrenal cortex is peripherally located
and makes up 80-90% of the total weight of the gland The cortex is
subdivided into three zones, each of which secretes a different
group of steroid hormones, all formed from the cholesterol
molecule
Slide 9
Just deep to the CT capsule, the cells of the zona glomerulosa
synthesize mineralocorticoid hormones The middle zone, or zona
fasciculata, secrete mainly glucocorticoid hormones, primarily
cortisol The inner zona reticularis is the site of synthesis of
weak androgens (masculinizing hormones) Adrenocortical
Hormones
Slide 10
Mineralocorticoids regulate the concentrations of Na + and K +
in the blood (affects blood volume/pressure) Aldosterone is the
major hormone in this group Glucocorticoids influence glucose
metabolism and the ability to resists the effects of stress
Cortisol is the major hormone in this group Weak androgens
(masculinizing sex hormones) have little effect in men, but play an
important role in promoting libido in women Adrenocortical
Hormones
Slide 11
The most important effects of aldosterone is seen in the
renin-angiotensin-aldosterone system (RAAS) The RAAS is stimulated
by a decrease in blood volume and/or blood pressure as in cases of
dehydration or hemorrhage. Low BP stimulates juxtaglomerular cells
in the kidney to secrete the enzyme renin RAAS
Slide 12
Renin converts the plasma protein angiotensinogen (produced in
the liver) into angiotensin I. As angiotensin I circulates to the
lungs, an enzyme called angiotensin converting enzyme (ACE)
converts angiotensin I to angiotensin II Angiotensin II stimulates
the adrenal cortex to secrete aldosterone (salt and H 2 0
resorption indirectly increases BP), and it is a potent
vasoconstrictor (which directly increases BP)
Slide 13
RAAS
Slide 14
Glucocorticoids Glucocorticoids (mainly cortisol) regulate
metabolism by promoting the breakdown of proteins and fats to form
glucose (gluconeogenesis). Increased blood sugar levels assist the
body to cope with stress Their inflammatory effects result from
inhibiting white blood cells. Unfortunately they also retard tissue
repair and slow wound healing glucocorticoids are very useful in
the treatment of chronic inflammatory disorders such as Lupus,
though long term side-effects are severe
Slide 15
Glucocorticoids High levels of circulating cortisol, as seen
with corticosteroid drugs (prednisone), or tumors (adrenal cortex,
pituitary gland) is called Cushings syndrome Manifestations include
hyper- glycemia, poor wound healing, osteoporosis, dermatitis, fat
redistribution (spindly arms and legs, moon face, buffalo hump at
the neck), and truncal obesity
Slide 16
Glucocorticoids In adults, hyposecretion of glucocorticoids and
aldosterone, usually as a result of an autoimmune disorder, is
called Addisons disease The physiologic effects include
hypoglycemia, Na + loss, low BP, dehydration, and muscle weakness
only after his death did the world learn that President Kennedy
suffered from Addisons disease
Slide 17
The Adrenal Medulla The inner region of the adrenal gland, the
adrenal medulla, is a modified sympathetic ganglion that develops
from the same embryonic tissue as all other sympathetic ganglia of
the ANS and is innervated by sympathetic preganglionic neurons The
catecholamines epinephrine (80%), and norepinephrine (20%), are
secreted at the adrenal medulla and serve to prolong the
sympathetic response
Slide 18
ADRENAL MEDULLA HORMONES (Interactions Animation)
Epinephrine/Norepinephrine You must be connected to the internet to
run this animation
Slide 19
The Pancreas The pancreas is both an endocrine and an exocrine
gland. It is located posterior and inferior to the stomach. We will
discuss its endocrine functions here and its exocrine functions in
detail in chapter 24
Slide 20
Most of the exocrine cells of the pancreas are arranged in
clusters called acini and produce digestive enzymes which flow
through ducts into the GI tract Distributed among the acini are
clusters of endocrine tissue called pancreatic islets (islets of
Langerhans) The Pancreas
Slide 21
Each pancreatic islet contains four types of hormone-secreting
cells: alpha (A), beta (B), delta (D), and F cells Alpha cells
secrete glucagon which increases blood glucose levels by acting on
hepatocytes to convert glycogen to glucose Beta cells secrete
insulin Pancreatic Hormones
Slide 22
Insulin is an anabolic hormone - it decreases blood glucose
levels by acting on hepatocytes to convert glucose to glycogen and
then facilitating diffusion of glucose into the cells Insulin and
glucagon are counter- regulatory hormones in that their actions act
to balance one another in terms of blood glucose
Slide 23
Somatostatin acts in a paracrine manner to inhibit both insulin
and glucagon release from neighboring beta and alpha cells. It also
inhibits the secretion of hGH The interactions of the four
pancreatic hormones are complex and not completely understood
Pancreatic Hormones
Slide 24
Low blood glucose (hypoglycemia) stimulates alpha cells to
secrete 1 GLUCAGON Glucagon acts on hepatocytes (liver cells) to:
convert glycogen into glucose (glycogenolysis) form glucose from
lactic acid and certain amino acids (gluconeogenesis) Low blood
glucose (hypoglycemia) stimulates alpha cells to secrete GLUCAGON 1
2 Glucagon acts on hepatocytes (liver cells) to: convert glycogen
into glucose (glycogenolysis) form glucose from lactic acid and
certain amino acids (gluconeogenesis) Glucose released by
hepatocytes raises blood glucose level to normal Low blood glucose
(hypoglycemia) stimulates alpha cells to secrete GLUCAGON 1 2 3
Glucagon acts on hepatocytes (liver cells) to: convert glycogen
into glucose (glycogenolysis) form glucose from lactic acid and
certain amino acids (gluconeogenesis) Glucose released by
hepatocytes raises blood glucose level to normal If blood glucose
continues to rise, hyperglycemia inhibits release of glucagon Low
blood glucose (hypoglycemia) stimulates alpha cells to secrete
GLUCAGON 1 2 3 4 Glucagon acts on hepatocytes (liver cells) to:
convert glycogen into glucose (glycogenolysis) form glucose from
lactic acid and certain amino acids (gluconeogenesis) Glucose
released by hepatocytes raises blood glucose level to normal If
blood glucose continues to rise, hyperglycemia inhibits release of
glucagon Low blood glucose (hypoglycemia) stimulates alpha cells to
secrete High blood glucose (hyperglycemia) stimulates beta cells to
secrete GLUCAGON 15 2 3 4 INSULIN Insulin acts on various body
cells to: accelerate facilitated diffusion of glucose into cells
speed conversion of glucose into glycogen (glycogenesis) increase
uptake of amino acids and increase protein synthesis speed
synthesis of fatty acids (lipogenesis) slow glycogenolysis slow
gluconeogenesis Glucagon acts on hepatocytes (liver cells) to:
convert glycogen into glucose (glycogenolysis) form glucose from
lactic acid and certain amino acids (gluconeogenesis) Glucose
released by hepatocytes raises blood glucose level to normal If
blood glucose continues to rise, hyperglycemia inhibits release of
glucagon Low blood glucose (hypoglycemia) stimulates alpha cells to
secrete High blood glucose (hyperglycemia) stimulates beta cells to
secrete INSULINGLUCAGON 15 2 3 4 6 Insulin acts on various body
cells to: accelerate facilitated diffusion of glucose into cells
speed conversion of glucose into glycogen (glycogenesis) increase
uptake of amino acids and increase protein synthesis speed
synthesis of fatty acids (lipogenesis) slow glycogenolysis slow
gluconeogenesis Blood glucose level falls Glucagon acts on
hepatocytes (liver cells) to: convert glycogen into glucose
(glycogenolysis) form glucose from lactic acid and certain amino
acids (gluconeogenesis) Glucose released by hepatocytes raises
blood glucose level to normal If blood glucose continues to rise,
hyperglycemia inhibits release of glucagon Low blood glucose
(hypoglycemia) stimulates alpha cells to secrete High blood glucose
(hyperglycemia) stimulates beta cells to secrete INSULINGLUCAGON 15
2 3 4 6 7 Insulin acts on various body cells to: accelerate
facilitated diffusion of glucose into cells speed conversion of
glucose into glycogen (glycogenesis) increase uptake of amino acids
and increase protein synthesis speed synthesis of fatty acids
(lipogenesis) slow glycogenolysis slow gluconeogenesis If blood
glucose continues to fall, hypoglycemia inhibits release of insulin
Blood glucose level falls Glucagon acts on hepatocytes (liver
cells) to: convert glycogen into glucose (glycogenolysis) form
glucose from lactic acid and certain amino acids (gluconeogenesis)
Glucose released by hepatocytes raises blood glucose level to
normal If blood glucose continues to rise, hyperglycemia inhibits
release of glucagon Low blood glucose (hypoglycemia) stimulates
alpha cells to secrete High blood glucose (hyperglycemia)
stimulates beta cells to secrete INSULINGLUCAGON 15 2 3 4 6 7 8
Glucose/Insulin Regulation
Slide 25
PANCREATIC HORMONES (Interactions Animation) Insulin You must
be connected to the internet to run this animation
Slide 26
Gonadal Hormones The ovaries are paired oval bodies located in
the female pelvic cavity. They produce several steroid hormones
including two estrogens (estradiol and estrone), progesterone,
relaxin, and inhibin Estrogens, along with FSH and LH from the
anterior pituitary, regulate the menstrual cycle, maintain
pregnancy, and prepare the mammary glands for lactation
Slide 27
Gonadal Hormones Ovarian hormones also promote enlargement of
the breasts and widening of the hips at puberty, and help maintain
these female secondary sex characteristics Progesterone prepares
the uterus lining for implantation of a fertilized ovum
Slide 28
OVARIAN HORMONES (Interactions Animation) Hormonal Regulation
of Female Reproductive System Hormonal Regulation of Female
Reproductive System You must be connected to the internet to run
this animation
Slide 29
Gonadal Hormones The male gonads, the testes, are oval glands
that lie in the scrotum. The main hormone produced and secreted by
the testes is testosterone, an androgen (male sex hormone)
Testosterone is needed for production of sperm and maintenance of
male secondary sex characteristics
Slide 30
TESTICULAR HORMONES (Interactions Animation) Hormonal
Regulation of Male Reproductive Function Hormonal Regulation of
Male Reproductive Function You must be connected to the internet to
run this animation
Slide 31
The Pineal Gland The pineal gland is a small endocrine gland
attached to the roof of the third ventricle it is part of the
epithalamus The pineal gland secretes the hormone melatonin, which
contributes to maintaining the biological clock (seasonal and daily
cycles) more melatonin is secreted in darkness; the pineal gland is
very developed in nocturnal animals
Slide 32
The Thymus gland The thymus gland secretes thymosin, which
promotes the proliferation and maturation of T cells T cells are a
type of white blood cell (lymphocyte) that destroys microorganisms
and foreign substances through direct cellular contact
Slide 33
General Adaptation Syndrome The general adaptation syndrome
(GAS) or stress response refers to the consequences of failure to
respond appropriately to emotional or physical threats, whether
actual or imagined Interestingly, stressful situations can be
events normally considered to be good, as well as bad for instance,
a marriage can be as stressful as a divorce, a birth as stressful
as a death, etc.
Slide 34
General Adaptation Syndrome It is impossible to remove all of
the stress from our everyday lives, and some levels of stress
actually help us perform well and be productive. Regardless, the
bodys homeostatic mechanisms attempt to counteract stress, and
maintain a constant internal environment whenever possible If
stress is extreme, unusual, or long lasting, the normal mechanisms
may not be enough, and they may elicit a series of changes called
the stress response or GAS
Slide 35
General Adaptation Syndrome There are three stages to a
prolonged stress response: alarm reaction, resistance reaction, and
exhaustion The alarm reaction is the short-lived fight-or- flight
response initiated by the hypothalamus and mediated by the
sympathetic division of the ANS it brings huge amounts of glucose
and oxygen to the brain, the lungs, and skeletal muscles the RAAS
is also activated to maintain blood volume and BP
Slide 36
THE ALARM REACTION (Interactions Animation) The Alarm Reaction
You must be connected to the internet to run this animation
Slide 37
General Adaptation Syndrome The three stages to the GAS
continued The resistance reaction is initiated in large part by
hypothalamic releasing hormones and is a longer-lasting response.
The release of high levels of cortisol and thyroid hormones assures
that the tissues of the body can sustain necessary metabolic
needs
Slide 38
General Adaptation Syndrome The alarm reaction leads to a
resistance response.
Slide 39
General Adaptation Syndrome The three stages to the GAS
continued Exhaustion occurs when the bodys reserves become so
depleted that they cannot sustain the resistance stage Prolonged
exposure to high levels of cortisol and other hormones causes
wasting of muscle, suppression of the immune system, ulceration of
the GI tract, and failure of pancreatic beta cells disease often
ensues
Slide 40
THE GAS (Interactions Animation) General Adaptation Syndrome
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Slide 41
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