Prepared By Moomin Zahoor

Student GMC _Rajouri

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Endocrine Glands PHYSIOLOGY

Definition, classification of endocrine glands and their hormones, properties of hormones

Endocrine glands are a group of specialized organs that produce and secrete hormones into the
bloodstream to regulate various bodily functions. There are several different types of endocrine glands,
each with their unique set of hormones and functions:

Pituitary Gland: This gland is often referred to as the "master gland" because it regulates the activity of
other endocrine glands in the body. The pituitary gland produces hormones such as growth hormone,
thyroid-stimulating hormone, adrenocorticotropic hormone, and prolactin.

Thyroid Gland: This gland is responsible for producing hormones that regulate metabolism and growth.
The thyroid gland produces hormones such as thyroxine and triiodothyronine.

Adrenal Glands: These glands produce hormones that regulate stress and blood pressure. The adrenal
glands produce hormones such as cortisol, adrenaline, and aldosterone.

Pancreas: This gland produces hormones that regulate blood sugar levels. The pancreas produces
insulin and glucagon.

Ovaries and Testes: These glands produce hormones that regulate reproductive functions. The ovaries
produce estrogen and progesterone, while the testes produce testosterone.

Hormones are chemical messengers produced by endocrine glands that regulate various bodily
functions. They can be classified into three types based on their chemical structure:

Amino acid-based hormones: These hormones are made from amino acids and include hormones
such as adrenaline and thyroxine.

Peptide hormones: These hormones are made from chains of amino acids and include hormones such
as insulin and growth hormone.

Steroid hormones: These hormones are made from cholesterol and include hormones such as
testosterone and estrogen.

Properties of hormones include:

Specificity: Hormones only affect specific cells or tissues that have receptors for that particular
hormone.

Potency: Hormones are potent in small quantities, and their effects can be amplified by a positive
feedback loop.

Half-life: Hormones have varying half-lives, meaning that they remain active in the body for different
periods.

Regulation: Hormone production and release are regulated by various factors such as feedback loops
and signals from the nervous system.

Thyroid gland hormone _ physiological, Anatomy, hormone secreted , physiological functions :-

The thyroid gland is a small, butterfly-shaped gland located in the neck region, just below the Adam's
apple. The thyroid gland produces two main hormones, thyroxine (T4) and triiodothyronine (T3), which
play a crucial role in regulating metabolism and other bodily functions.

Anatomy of the Thyroid Gland:

The thyroid gland consists of two lobes connected by a small band of tissue called the isthmus. It is
located in the neck region, just below the Adam's apple and in front of the windpipe. The thyroid gland
is supplied by a network of blood vessels, which help to deliver the necessary nutrients and oxygen for
hormone production.

Hormones Secreted by the Thyroid Gland:

The thyroid gland produces two main hormones, thyroxine (T4) and triiodothyronine (T3). These
hormones are synthesized from the amino acid tyrosine and the mineral iodine, which are obtained
from the diet. The thyroid gland also produces a hormone called calcitonin, which helps to regulate
calcium levels in the body.

Physiological Functions of Thyroid Hormones:

The thyroid hormones play a crucial role in regulating metabolism, which is the process by which the
body converts food into energy. They also help to regulate body temperature, heart rate, and the
production of proteins. Thyroid hormones are also important for growth and development, particularly
in children and teenagers. In addition, they play a role in maintaining the normal function of the nervous
system, digestive system, and reproductive system.

An imbalance in thyroid hormone levels can lead to a range of disorders, such as hypothyroidism
(underactive thyroid) and hyperthyroidism (overactive thyroid). Hypothyroidism can cause symptoms
such as fatigue, weight gain, and cold intolerance, while hyperthyroidism can cause symptoms such as
weight loss, anxiety, and heat intolerance.

Hypo and hyper secretion of hormone :-

Hyposecretion and hypersecretion refer to the underproduction and overproduction of hormones,

respectively. This can lead to various hormonal disorders and health problems.

Hyposecretion:
Hyposecretion occurs when an endocrine gland produces and secretes an insufficient amount of
hormone. This can be caused by various factors, such as damage or dysfunction of the gland,
autoimmune disorders, or a lack of necessary nutrients for hormone production. Some common
examples of hyposecretion disorders include:

Hypothyroidism: This condition occurs when the thyroid gland does not produce enough thyroid
hormone, leading to symptoms such as fatigue, weight gain, and cold intolerance.

Addison's disease: This condition occurs when the adrenal glands do not produce enough cortisol and
aldosterone, leading to symptoms such as fatigue, weight loss, and low blood pressure.

Type 1 diabetes: This condition occurs when the pancreas does not produce enough insulin, leading to
high blood sugar levels and other complications.

Hypersecretion:
Hypersecretion occurs when an endocrine gland produces and secretes an excessive amount of
hormone. This can be caused by various factors, such as tumors or overstimulation of the gland. Some
common examples of hypersecretion disorders include:

Hyperthyroidism: This condition occurs when the thyroid gland produces too much thyroid hormone,
leading to symptoms such as weight loss, anxiety, and heat intolerance.

Cushing's syndrome: This condition occurs when the adrenal glands produce too much cortisol, leading
to symptoms such as weight gain, high blood pressure, and mood changes.

Acromegaly: This condition occurs when the pituitary gland produces too much growth hormone,
leading to excessive growth of tissues and bones.
Treatment for hypo and hypersecretion disorders depends on the specific disorder and may involve
hormone replacement therapy, medications, or surgery.

Adrenal gland in detail :-

The adrenal glands are a pair of small triangular-shaped glands located on top of the kidneys. They are
part of the endocrine system and play an important role in regulating various bodily functions.

Anatomy of the Adrenal Glands:

The adrenal glands are divided into two parts, the outer layer called the adrenal cortex, and the inner
layer called the adrenal medulla.

The adrenal cortex is further divided into three zones: the zona glomerulosa, zona fasciculata, and zona
reticularis. Each of these zones produces different hormones that play different roles in the body. The
zona glomerulosa produces mineralocorticoids, such as aldosterone, which helps to regulate salt and
water balance in the body. The zona fasciculata produces glucocorticoids, such as cortisol, which help
to regulate metabolism, blood sugar levels, and immune system function. The zona reticularis produces
androgens, such as DHEA (dehydroepiandrosterone), which are important for sexual development and
function.

The adrenal medulla is responsible for producing two main hormones, epinephrine (adrenaline) and
norepinephrine (noradrenaline), which play a role in the body's "fight or flight" response. These
hormones are released in response to stress and help to increase heart rate, blood pressure, and
respiration, among other physiological responses.

Physiological Functions of the Adrenal Glands:

The adrenal glands play a vital role in regulating various bodily functions, including:

Regulation of salt and water balance: The mineralocorticoids produced by the adrenal cortex, such as
aldosterone, help to regulate salt and water balance in the body.

Regulation of metabolism and blood sugar levels: The glucocorticoids produced by the adrenal cortex,
such as cortisol, help to regulate metabolism and blood sugar levels in the body.

Immune system function: Cortisol plays a role in regulating immune system function, helping to reduce
inflammation and suppress the immune response.

Sexual development and function: The androgens produced by the adrenal cortex, such as DHEA, play
a role in sexual development and function.

Response to stress: The hormones produced by the adrenal medulla, such as epinephrine and
norepinephrine, help to increase heart rate, blood pressure, and respiration in response to stress.

Disorders of the Adrenal Glands:

There are several disorders that can affect the function of the adrenal glands, such as:

Adrenal insufficiency: This occurs when the adrenal glands do not produce enough hormones, leading
to symptoms such as fatigue, weakness, and weight loss.

Cushing's syndrome: This occurs when the adrenal glands produce too much cortisol, leading to
symptoms such as weight gain, high blood pressure, and mood changes.

Pheochromocytoma: This is a rare tumor of the adrenal medulla that can lead to excessive production
of epinephrine and norepinephrine, causing symptoms such as high blood pressure, palpitations, and
sweating.

Treatment for adrenal disorders depends on the specific disorder and may involve hormone
replacement therapy, medications, or surgery.

Functions of adrenaline and nor adrenaline :

Adrenaline (epinephrine) and noradrenaline (norepinephrine) are hormones produced by the adrenal
medulla, which is located in the center of the adrenal gland. They play a key role in the body's "fight or
flight" response to stress and are involved in several physiological functions.

Here are some of the functions of adrenaline and noradrenaline:

Increases heart rate and blood pressure: Adrenaline and noradrenaline help to increase heart rate and
blood pressure, which helps to deliver more oxygen and nutrients to the muscles during times of stress.

Dilates air passages: Adrenaline and noradrenaline help to dilate the air passages in the lungs, which
helps to increase oxygen intake during times of stress.

Increases blood sugar levels: Adrenaline and noradrenaline help to increase blood sugar levels by
stimulating the liver to release glucose into the bloodstream, providing the body with energy during
times of stress.

Constricts blood vessels in non-essential organs: Adrenaline and noradrenaline help to constrict blood
vessels in non-essential organs such as the skin and digestive system, redirecting blood flow to the
muscles and brain during times of stress.

Triggers the release of stored energy: Adrenaline and noradrenaline help to trigger the release of stored
energy from fat cells and muscle tissue, providing the body with additional energy during times of
stress.

Increases mental alertness and focus: Adrenaline and noradrenaline help to increase mental alertness
and focus, which can be helpful during times of stress.

Overall, adrenaline and noradrenaline play a key role in the body's response to stress and are important
for increasing physical and mental performance during times of stress or danger. However, excessive
or prolonged release of these hormones can have negative effects on the body, such as increasing the
risk of heart disease and high blood pressure.

Pituitary gland in detail

The pituitary gland, also known as the "master gland," is a small, pea-sized gland located at the base
of the brain. It is part of the endocrine system and plays a crucial role in regulating various bodily
functions.

Anatomy of the Pituitary Gland:

The pituitary gland is divided into two main parts, the anterior pituitary and the posterior pituitary.

The anterior pituitary is the larger of the two parts and is responsible for producing and releasing
several hormones, including growth hormone, thyroid-stimulating hormone, adrenocorticotropic
hormone, follicle-stimulating hormone, luteinizing hormone, and prolactin.

The posterior pituitary is responsible for storing and releasing two hormones produced by the
hypothalamus, oxytocin, and antidiuretic hormone (ADH).

Physiological Functions of the Pituitary Gland:

The pituitary gland plays a vital role in regulating various bodily functions, including:

Growth and development: The growth hormone produced by the anterior pituitary plays a key role in
regulating growth and development, particularly during childhood and adolescence.

Reproduction: The follicle-stimulating hormone and luteinizing hormone produced by the anterior
pituitary play a key role in regulating reproductive function, including the production of sperm in men
and the maturation of eggs in women.

Metabolism: The thyroid-stimulating hormone produced by the anterior pituitary plays a key role in
regulating metabolism, including the production of thyroid hormones by the thyroid gland.
Stress response: The adrenocorticotropic hormone produced by the anterior pituitary plays a key role in
regulating the body's response to stress, including the production of cortisol by the adrenal glands.

Water balance: The antidiuretic hormone produced by the posterior pituitary plays a key role in
regulating water balance in the body by controlling the amount of water excreted by the kidneys.

Milk production: The prolactin produced by the anterior pituitary plays a key role in stimulating milk
production in nursing mothers.

Disorders of the Pituitary Gland:

There are several disorders that can affect the function of the pituitary gland, such as:

Pituitary tumors: Tumors of the pituitary gland can lead to overproduction or underproduction of certain
hormones, causing a range of symptoms depending on which hormone is affected.

Diabetes insipidus: This occurs when the posterior pituitary does not produce enough antidiuretic
hormone, leading to excessive thirst and urination.

Hypopituitarism: This occurs when the pituitary gland does not produce enough hormones, leading to a
range of symptoms depending on which hormones are affected.

Acromegaly: This occurs when the anterior pituitary produces too much growth hormone, leading to
abnormal growth of the hands, feet, and face.

Treatment for pituitary disorders depends on the specific disorder and may involve hormone
replacement therapy, medications, or surgery.

Pancreas_ hormones of pancreas.insulin _secrection , regulation, function and action

The pancreas is a glandular organ located behind the stomach that produces hormones and digestive
enzymes. The pancreas has both endocrine and exocrine functions, meaning that it produces
hormones that are released into the bloodstream and also enzymes that are released into the digestive
tract to help with the digestion of food.

The endocrine function of the pancreas is primarily controlled by clusters of cells called islets of
Langerhans, which contain different types of cells that produce different hormones. The two main
hormones produced by the pancreas are insulin and glucagon.

Insulin:

Insulin is a hormone produced by beta cells in the islets of Langerhans in the pancreas. It is released
into the bloodstream in response to high levels of glucose in the blood, such as after a meal.

Regulation of insulin secretion:

Insulin secretion is regulated by a negative feedback mechanism. When glucose levels in the blood
rise, the pancreas secretes insulin, which helps to lower blood glucose levels by promoting glucose
uptake by cells and storing glucose in the liver and muscles. As blood glucose levels decrease, insulin
secretion decreases, helping to maintain blood glucose levels within a normal range.

Functions and actions of insulin:

Promotes glucose uptake: Insulin promotes the uptake of glucose by cells, especially muscle, liver, and
adipose tissue. This helps to lower blood glucose levels and provides cells with energy.

Promotes glucose storage: Insulin promotes the storage of glucose in the liver and muscles as
glycogen, which can be used later as a source of energy.

Inhibits glucose production: Insulin inhibits glucose production in the liver, which helps to prevent
hyperglycemia.
Promotes protein synthesis: Insulin promotes protein synthesis in cells, which helps to build and repair
tissues.

Inhibits lipolysis: Insulin inhibits the breakdown of fat (lipolysis) and promotes the storage of fat in
adipose tissue, which helps to lower blood fatty acid levels.

Disorders related to insulin secretion:

Diabetes mellitus: Diabetes mellitus is a condition characterized by high blood glucose levels due to
insufficient insulin secretion (Type 1 diabetes) or insulin resistance (Type 2 diabetes).

Hypoglycemia: Hypoglycemia is a condition characterized by low blood glucose levels due to

excessive insulin secretion or other factors.

Insulinoma: Insulinoma is a type of pancreatic tumor that secretes insulin, leading to hypoglycemia.

Treatment of disorders related to insulin secretion:

The treatment of diabetes mellitus and hypoglycemia typically involves insulin therapy, which may be
administered by injection or insulin pump. Other treatments may include dietary modifications,
exercise, and medication to help regulate blood glucose levels. Insulinoma is typically treated with
surgery to remove the tumor.

Diabetes mellitus _ regulation of blood glucose level

Diabetes mellitus is a chronic metabolic disorder characterized by high blood glucose levels
(hyperglycemia) due to insufficient insulin production (Type 1 diabetes) or insulin resistance (Type 2
diabetes).

Regulation of blood glucose levels in diabetes mellitus:

Insulin therapy: In Type 1 diabetes, insulin therapy is necessary to regulate blood glucose levels. Insulin
therapy may be administered by injection or insulin pump, and the dosage may be adjusted based on
blood glucose monitoring results.

Medication: In Type 2 diabetes, medication may be prescribed to help regulate blood glucose levels.
Medications may include oral hypoglycemic agents, such as metformin, which helps to lower blood
glucose levels by decreasing glucose production in the liver and increasing insulin sensitivity.

Diet: A healthy diet is important in managing diabetes mellitus. A diet rich in fiber, whole grains, fruits,
vegetables, lean protein, and healthy fats can help to regulate blood glucose levels. Carbohydrate
intake should be monitored and distributed throughout the day to prevent blood glucose spikes.

Exercise: Regular exercise can help to regulate blood glucose levels by increasing insulin sensitivity and
glucose uptake by cells. Exercise may also help to reduce insulin resistance and improve overall health.

Blood glucose monitoring: Regular blood glucose monitoring is necessary in diabetes mellitus to
monitor blood glucose levels and adjust insulin therapy or medication dosage as needed.

Complications of uncontrolled blood glucose levels:

Uncontrolled blood glucose levels in diabetes mellitus can lead to various complications, including:

Cardiovascular disease: High blood glucose levels can damage blood vessels and increase the risk of
cardiovascular disease.

Neuropathy: High blood glucose levels can damage nerves, leading to numbness, tingling, and pain in
the hands and feet.

Retinopathy: High blood glucose levels can damage the blood vessels in the eyes, leading to vision
problems and even blindness.
Nephropathy: High blood glucose levels can damage the kidneys, leading to kidney failure.

Infections: High blood glucose levels can impair the immune system, increasing the risk of infections.

Prevention of complications:

Preventing complications in diabetes mellitus involves maintaining tight control of blood glucose levels
through proper medication management, regular blood glucose monitoring, healthy lifestyle habits, and
regular check-ups with a healthcare provider.

Parathyroid gland _function , action, regulation of secretion

The parathyroid gland is a small endocrine gland located near the thyroid gland in the neck. The
parathyroid gland secretes parathyroid hormone (PTH), which plays a crucial role in regulating calcium
levels in the body.

Functions and actions of parathyroid hormone:

Regulates calcium levels: PTH regulates calcium levels in the blood by increasing calcium absorption in
the intestines, increasing calcium reabsorption in the kidneys, and releasing calcium from bones.

Stimulates vitamin D production: PTH stimulates the production of active vitamin D in the kidneys,
which helps to increase calcium absorption in the intestines.

Maintains bone health: PTH is essential for maintaining bone health by stimulating bone resorption,
which releases calcium and phosphorus into the blood. This helps to maintain calcium and phosphorus
levels in the blood, which are necessary for bone mineralization.

Regulation of parathyroid hormone secretion:

The secretion of parathyroid hormone is regulated by a negative feedback loop that involves calcium
levels in the blood.

Low calcium levels in the blood: When blood calcium levels are low, parathyroid gland cells called chief
cells are stimulated to release PTH into the blood.

Increased calcium levels in the blood: When blood calcium levels are high, the secretion of PTH is
inhibited through a negative feedback loop.

In addition to calcium levels, other factors that can affect PTH secretion include vitamin D levels,
magnesium levels, and certain hormones such as calcitonin, which is secreted by the thyroid gland and
helps to lower blood calcium levels.

Overall, the parathyroid gland and PTH play an important role in regulating calcium levels in the body,
which is essential for bone health and proper functioning of various organs and systems in the body.

Calcitonin _ function and action

Calcitonin is a hormone secreted by the thyroid gland in response to high levels of calcium in the blood.
Calcitonin plays an important role in regulating calcium homeostasis in the body.

Function and action of calcitonin:

Lowers blood calcium levels: Calcitonin lowers blood calcium levels by inhibiting the activity of
osteoclasts, which are cells that break down bone tissue and release calcium into the blood. This helps
to reduce calcium levels in the blood.

Increases bone formation: Calcitonin stimulates osteoblasts, which are cells that build bone tissue. This
helps to increase bone formation, which can help to offset the effects of osteoclast activity.
Promotes calcium excretion: Calcitonin promotes the excretion of calcium in the kidneys, which helps
to reduce calcium levels in the blood.

Overall, calcitonin works in opposition to parathyroid hormone (PTH), which increases blood calcium
levels. Together, calcitonin and PTH help to maintain calcium homeostasis in the body.

Although calcitonin plays an important role in regulating calcium levels, it is not considered to be
essential for calcium homeostasis in humans. In fact, some individuals may have undetectable levels of
calcitonin and still maintain normal calcium levels. However, calcitonin may have other physiological
effects, such as regulating bone remodeling and influencing the activity of immune cells.