Hormones Secreted By Parathyroid Gland

PARATHYROID GLAND

INTRODUCTION:

Parathyroid glands are four small glands of the endocrine system which regulate the calcium in our bodies. Parathyroid glands are located in the neck behind the thyroid where they continuously monitor and regulate blood calcium levels.

  

HORMONES SECRETED BY PARATHYROID GLAND

PARATHYROID HORMONE ( PTH ):

The parathyroids produce a hormone called parathyroid hormone ( PTH ). PTH raises the blood calcium level by breaking down the bone ( where most of the body’s calcium is stored ) and causing calcium release.

INTRODUCTION OF PTH:

Parathyroid glands are small endocrine glands in the neck of humans and other tetrapods. The parathyroid gland produces and secretes parathyroid hormone in response to allow blood calcium, which plays a key role in regulating the amount of calcium in the blood and within the bones.

STRUCTURE OF PARATHYROID HORMONE;

PTH is secreted primarily by the chief cells of the parathyroid glands. It is a polypeptide containing 84 amino acids, which is a prohormone. It has a molecular mass around 9500 Da. Its action is opposed by the hormone calcitonin.

PHYSIOLOGICAL ROLE OF PARATHYROID HORMONE

Parathyroid hormone regulates  serum calcium through its effects on bone, kidney and the intestine. In bone, PTH enhances the release of calcium from the large reservoir contained in the bones. Bone resorption is the normal destruction of bone by osteoclasts, which are indirectly stimulated by PTH.

DISORDERS OF PARATHYROID GLAND

·            Hypercalcemia: hypercalcemia means elevated blood level of calcium

·            Hypocalcemia: hypocalcemia means decreased blood level of calcium

·            Primary hyperparathyroidism

·            Secondary hyperparathyroidism

·            Tertiary hyperparathyroidism

·            Hypoparathyroidism

·            Pseudohypoparathyroidism

·            Parathyroid cancer

HYPERCALCEMIA

INTRODUCTION:

Hypercalcemia is a condition in which you have too high a concentration of calcium in your blood. Calcium is essential for the normal function of organs, cells, muscles, and nerves. It’s also important in blood clotting and bone health.

        However, too much of it can cause problems. Hypercalcemia makes it hard for the body to carry out its normal fuctions. Extremely high levels of calcium can be life- threatening.

CAUSES OF HYPERCALCEMIA:

·         Cancers, especially lung cancer and breast cancer

·         Immobilization over a long period of time

·         Kidney failure

·         Overactive thyroid ( hyperthyroidism ) or excessive thyroid hormone intake.

·         Use of certain medications such as the thiazide diuretics

·         Inherited kidney or metabolic conditions

SYMPTOMS OF HYPERCALCEMIA:

·            Loss of apetite

·            Nausea and vomiting

·            Constipation and abdominal pain

·            Increased thirst and frequent urination

·            Fatigue, weakness and muscle pain

·            Confusion, disorientation and difficulty thinking

·            Headaches

·            Depression

AFFECTED POPULATION BY HYPERCALCEMIA:

Hypercalcemia is relatively common. Primary hyperparathyroidism occurs in 1-7 per 1,000 people, and hypercalcemia occurs in about 2.7% of those with cancer.

HYPOPARATHYROIDISM

INTRODUCTION:

Hypoparathyroidism is an uncommon endocrine deficiency disease resulting from decreased function of the parathyroid glands, with underproduction of parathyroid hormone ( PTH ). Secondary hypoparathyroidism is a physiologic state in which PTH levels are low in response to a primary process that cause hypercalcemia.

CAUSES OF HYPOPARATHYROIDISM:

·         Injury to or removal of the parathyroid glands.

·         DiGeorge syndrome, which is a genetic disorder that affects development of certain body systems.

·         Genetics

·         Autoimmune disease

·         Cancer radiation treatments.

·         Low magnesium levels.

SYMPTOMS OF HYPOPARATHYROIDISM:

·         Muscle aches or cramps

·         Tingling, burning or numbness in the fingertips, toes and lips.

·         Muscle spasms, especially around the mouth.

·         Patchy hair loss

·         Dry skin

·         Fatigue

POPULATION AFFECTED BY HYPOPARATHYROIDISM:

There are approximately 70,000 people  withhypoparathyroidism in the United States. Hypoparathyroidism can affect individuals of any age.

Hormones Secreted By Thymus Gland

INTRODUCTION OF THYMUS GLAND

“The thymus get its name from its silhouette. It is shaped much like a thyme leaf, a common  cooking herb. It has two separate lobes divided by a central medulla and a peripheral cortex”

·         The thymus gland is both an endocrine gland & lymphatic organs.

·         The thymus secretes a large number of hormones.

·         It is composed of two lobes & is located in front of the heart & behind the sternum.

·         Thymus is specialized organ in the immune system.

·         After puberty, it decreases in size and is slowly replaced by fat.

·         The thymus reached its maximum weight ( about 1 ounce ) during puberty.

             The thymus gland will not function throughout a full lifetime, but it has a big responsibility when it’s active- helping the body protect itself against autoimmunity, which occurs when the immune system turns against itself.

               Therefore, the thymus plays a vital role in the lymphatic system ( your body’s defense network ) and endocrine system.

                The thymus is special in that, unlike most organs, it is at its largest in children. Once you reach puberty, the thymus starts to slowly shrink and become replaced by fat. By age 75, the thymus is little more than fatty tissue. Fortunately, the thymus produces all of your T cells by the time you reach puberty.

HORMONES SECRETED BY GLAND

·         Thymosin

·         Thymopoietin

THYMOSIN HORMONES

INTRODUCTION:

Thymosin is a hormone secreted by the thymus (an endocrine gland in the human body .

Thymosin stimulates the development of T cells. Throughout your childhood years, white blood cells called lymphocytes pass through the thymus, where they are transformed into T cells.

Thymosin α1 stimulates the development of precursor T cells in the thymus to mature T cells. Thymosin β4 is the principal G-actin sequestering molecule in mammalian cells, playing an important role in the organization of the cytoskeleton.

STRUCTURE

PHYSIOLOGICAL ROLE OF THYMOSIN

The roles of the hormone thymosin include activating the immune system by activating the T-cells ( T-killer Cells, T-Helper Cells and T-Memory  Cells ) which are types of lymphocytes in the blood.

THYMUS

THYMOPOIETIN HORMONE

INTRODUCTION:

Thymopoietin , a polypeptide hormone secreted by the thymus; it induces the proliferation of lymphocyte precursors and their differentiation into T-lymphocytes.

STRUCTURE

PHYSIOLOGICAL ROLE OF THYMOPOIETIN

Thymopoietin is a polypeptide hormone secreted by the thymus that affect the rate at which your skin ages. Simply put, thymopoietin affect the body’s capacity to maintain youthful function in everything from skin cells to brain cells.

DISORDERS OF THYMUS GLAND

·         Myasthenia gravis

·         Pure red cell aplasia

·         Hypogammaglobulinemia

MYASTHENIA GRAVIS

INTRODUCTION;

Myasthenia gravis is an uncommon condition that causes certain muscles to become weak. With treatment, most people can lead a normal life.

Myasthenia gravis literally means ‘grave muscle weakness’.

The condition can affect any muscles that you can control voluntarily. Muscles that you cannot control voluntarily, such as the heart muscles, are not affected.

        Myasthenia gravis most commonly affects the muscles that control eye and eyelid movement, facial expression, chewing, swallowing and talking, and the muscles in the arms and legs. Less often, the muscles involved in breathing may be affected.

  The muscle weakness is usually made worse by physical activity and improved by rest

CAUSE: 

Myasthenia gravis is an autoimmune disease, which means that your immune system attacks your own body tissues. In the case of myasthenia gravis, your immune system produces antibodies that block or damage your muscle receptor cells. This blocks themessages that pass from the nerve endings to the muscles, so your muscles do not contract well and become weak.

        The reason why some people’s  immune systems make antibodies against muscle receptor cells is not fully understood.

SYMPTOMS: 

·         Trouble talking

·         Problems walking up stairs or lifting objects.

·         Facial paralysis

·         Difficulty breathing due to muscle weakness

·         Difficulty swallowing or chewing

·         Fatigue

·         hoarsevoice

·         drooping of eyelids etc.

AFFECTED PEOPLE BY MYASTHENIA GRAVIS:

Myasthenia gravis affects about 20 per 100,000 people worldwide. The prevalence has been increasing in recent decades, which likely results from earlier diagnosis and better treatments leading to longer lifespans for affected individuals.

PURE RED CELL APLASIA

INTRODUCTION:

Pure red cell aplasia ( PRCA ) or erythroblastopeniarefers to a type of anemia affecting the precursors to red blood cells. In PRCA, the bone marrow ceases to produce red blood cells.

CAUSES;

Acquired pure red cell aplasia is thought to be an autoimmune disorder possibly caused either by a tumor of the thymus gland, certain drugs or a viral infection is one of a group or bone marrow failure syndromes.

SYMPTOMS:

symptoms may include fatigue, lethargy, and/or abnormal paleness of the skin (pallor) due to the anemia the caused by the disorder

AFFECTED POPULATION BY ( PRCA ):

Acquired pure red cell aplasia is a rare disorder affecting males and females in equal numbers.

HYPOGAMMAGLOBULINEMIA

INTRODUCTION;

Hypogammaglobulinemia is a problem with the immune system in which not enough gamma globulins are produced in the blood ( thus hypo- + gamma + globulin + -emia ). This results in a lower antibody count, which impairs the immune system, increasing risk of infection.

CAUSES:

Hypogammaglobulinemia may result from a variety of primary genetic immune system defects, such as common variable immunodeficiency, or it may be caused by secondary effects such as medication, blood cancer or poor nutrition, or loss of gamma globulins in urine as in nonselective glomerular proteinuria.

SYMPTOMS:

·         Coughing

·         Sore throat

·         Fever

·         Ear pain

·         Congestion

·         Sinus pain

·         Diarrhea

·         Nausea and vomiting

AFFECTED POPULATION BY

HYPOGAMMAGLOBULINEMIA:

CVID is the second most common cause of hypogammaglobulinemia  and affects both sexes equally. The incidence is about 1 in 50,000 people. In most patients there is a reduced amount of the immunoglobulinsIgG, IgA and IgM in the blood. It is an immune deficiency disorder that can be acquired or inherited.

FEMALE REPRODUCTIVE HORMONES

Introduction

A type of hormones involved in fertility and sexuality. Female reproductive hormones include estrogen and progesterone. They help develop and maintain female sex characteristics and play an important role in the menstrual cycle, fertility, and pregnancy.

 the various functions of the body are regulated by the nervous system and the hormonal system. Both these systems are involved in controlling the activity of the female reproductive system in a regular monthly series of events known as the menstrual cycle

HORMONES REGULATING THE FEMALE REPRODUCTIVE SYSTEM

·         Gonadotropin-releasing hormone (GnRH)

·         Follicle-stimulating hormone (FSH)

·         Leutenizing hormone (LH)

·         Oestrogen

·         Progesterone

HYPOTHALAMUS

Introduction

The hypothalamus is a small region of the brain. It's located at the base of the brain, near the pituitary gland. While it's very small, the hypothalamus plays a crucial role in many important functions, including: releasing hormones. regulating body temperature.

GONADOTROPIN-RELEASING HORMONE (GNRH)

Introduction

Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. GnRH is a tropicpeptide hormone synthesized and released from GnRH neurons within the hypothalamus. The peptide belongs to gonadotropin-releasing hormone family. It constitutes the initial step in the hypothalamic–pituitary–gonadal axis.

Structure

Physiological Role:

 In the brain, GnRH I and II apparently modulate mammalian reproductive behaviours in different but complementary ways: GnRH I stimulates luteinizing hormone/follicle‐stimulating hormone secretion (and thus gonadal steroids) and promotes sexual behaviour in ad libitum fed animals. By contrast, GnRH II acts as a permissive regulator of female reproductive behaviour based on energy status, as well as a modifier of short‐term food intake. GnRH II has also been implicated in the regulation of calcium and potassium channels in nervous systems of amphibians, functions which may also be present in mammals. Increasing evidence suggests that the effects of GnRH II in both the periphery and brain may be mediated by GnRH receptor subtypes distinct from the type‐1 GnRH receptor. It is likely that this evolutionarily conserved peptide has been co‐opted over evolutionary time to possess multiple regulatory functions in a broad range of biological aspects, including, but not limited to, reproduction. Here, the proposed actions of both neural and peripheral GnRH II in affecting physiology and behaviour are summarized, and an outline of critical directions for future research is proposed.

DISORDERS

CAUSES

The Gonadotropin deficiency of hypogonadotropic hypogonadism is due to insufficient pulsatile secretion of GnRH or lack of ability to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH) leading to delayed sexual maturation. 

SYMPTOMS

Isolated gonadotropin-releasing hormone (GnRH) deficiency (IGD) is characterized by inappropriately low serum concentrations of the gonadotropins LH(luteinizing hormone) and FSH (follicle-stimulating hormone) in the presence of low circulating concentrations of sex steroids.

AFFECTED POPULATION

 In the general population the incidence of delayed puberty is less than 1%

THE PITUITARY GLAND 

Introduction

It is a small pea-sized gland that plays a major role in regulating vital body functions and general wellbeing. It is referred to as the body's 'mastergland' because it controls the activity of most other hormone-secreting glands

 

FOLLICLE-STIMULATING HORMONE (FSH)

Intoduction

Follicle-stimulating hormone (FSH) is a gonadotropin, a glycoprotein polypeptide hormone. FSH is synthesized and secreted by the gonadotropic cells of the anterior pituitary gland, and regulates the development, growth, pubertal maturation, and reproductive processes of the body.

Structure

Physiological Role

Estrogen Production

FSH stimulates granulosa cells in the ovarian follicles to synthesize aromatase, which converts androgens produced by the thecal cells to estradiol.

Follicular Development and the Menstrual Cycle

During the follicular phase of the menstrual cycle, FSH stimulates the maturation of ovarian follicles. As a dominant follicle takes over and secretes estradiol and inhibin, FSH secretion is suppressed. When the dominant follicle produces enough estradiol to maintain levels of 200 to 300 pg/ml for 48 hours, the hypothalamus responds with a surge of GnRH which stimulates the secretion of gonadotropic hormones instead inhibiting them. FSH peaks at the same time as the LH surge that causes ovulation. FSH then remains low throughout the luteal phase, preventing the development of new follicles.

 

LEUTENIZING HORMONE

Introduction

a hormone secreted by the anterior pituitary gland that stimulates ovulation in females and the synthesis of androgen in males.

Structure

 

PHYSIOLOGICAL ROLE

In men, luteinising hormone stimulates Leydig cells in the testes to produce testosterone, which acts locally to support sperm production. Testosterone also exerts effects all around the body to generate male characteristics such as increased muscle mass, enlargement of the larynx to generate a deep voice, and the growth of facial and body hair.

In women, luteinising hormone carries out different roles in the two halves of the menstrual cycle. In weeks one to two of the cycle, luteinising hormone is required to stimulate the ovarian follicles in the ovary to produce the female sex hormone, oestradiol. Around day 14 of the cycle, a surge in luteinising hormone levels causes the ovarian follicle to tear and release a mature oocyte (egg) from the ovary, a process called ovulation. For the remainder of the cycle (weeks three to four), the remnants of the ovarian follicle form a corpus luteum. Luteinising hormone stimulates the corpus luteum to produce progesterone, which is required to support the early stages of pregnancy, if fertilisation occurs.

DISORDERS OF FSH & LH

CAUSES

When a woman enters menopause and her ovaries stop working, FSH levels will rise. Low levels of FSH AND LH are consistent with secondary ovarian failure due to a pituitary disorder or hypothalamic problem. Low FSH serum levels have been associated with increased risk of ovarian cancer

SYMPTOMS

FSH and LH deficiency: In women, symptoms include irregular or stopped menstrual periods and infertility. In men, symptoms include loss of body and facial hair, weakness, lack of interest in sexual activity, erectile dysfunction, and infertility.

AFFECTED POPULATION

This condition affects both females and males who usually present with anosmia and delayed puberty.

OVARIES

Introduction

 Ovaries are grape-sized glands located by the uterus and are part of the endocrine system.. These glands have three important functions: they secrete hormones, they protect the eggs a female is born with and they release eggs for possible fertilization

OESTROGEN

Introduction

Estrogen, or oestrogen, is the primary female sex hormone. It is responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens in females that have estrogenic hormonal activity: estrone, estradiol, and estriol. The estrane steroid estradiol is the most potent and prevalent of these.

Structure

 

Physiological Role

puberty, estrogen plays a role in the development of so-called female secondary sex characteristics, such as breasts, wider hips, pubic hair and armpit hair.  

Estrogen also helps regulate the menstrual cycle, controlling the growth of the uterine lining during the first part of the cycle. If the woman's egg is not fertilized, estrogen levels decrease sharply and menstruation begins. If the egg is fertilized, estrogen works with progesterone, another hormone, to stop ovulation during pregnancy

During pregnancy, the placenta produces estrogen, specifically the hormone estriol. Estrogen controls lactation and other changes in the breasts, including at adolescence and during pregnancy. 

Estrogen is instrumental in bone formation, working with vitamin D, calcium and other hormones to effectively break down and rebuild bones according to the body's natural processes. As estrogen levels start to decline in middle age, the process of rebuilding bones slows, with postmenopausal women eventually breaking down more bone than they produce.

Estrogen can also help with ovarian cysts. "Most of the time nothing needs to be done to treat or prevent functional cysts,

Estrogen also plays a role in blood clotting, maintaining the strength and thickness of the vaginal wall and the urethral lining, vaginal lubrication and a host of other bodily functions.

It even affects skin, hair, mucous membranes and the pelvic muscles, according to Johns Hopkins Medicine. For example, estrogen can make the skin darker. Some researchers hope to use this information to create safe fake tanning lotions by activating the skin darkening reaction in estrogen, without triggering other changes in the body due to the hormone.

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Disorders;

CAUSES;

• Menopause
• Ovarian insufficiency: idiopathic or secondary to an underlying conditions (e.g., Turner syndrome, polycystic ovary syndrome)
• Congenital aromatase deficiency (↓ aromatase → ↑ androgens and ↓ estrogen)
• Hyperprolactinemia (e.g., in pituitary adenomas, hypothyroidism)

SYMPTOMS;

Common symptoms of low estrogen include:

·         painful sex due to a lack of vaginal lubrication.

·         an increase in urinary tract infections (UTIs) due to a thinning of the urethra.

·         irregular or absent periods.

·         mood swings.

·         hot flashes.

·         breast tenderness.

·         headaches or accentuation of pre-existing migraines.

·         depression.

affected population

Depression and anxiety affect women in their estrogen-producing years more often than men or postmenopausal women. Estrogen is also linked to mood disruptions that occur only in women 

PROGESTERONE

Introduction

Progesterone (P4) is an endogenous steroid and progestogen sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis of humans and other species. It belongs to a group of steroid hormones called the progestogens,and is the major progestogen in the body. Progesterone has a variety of important functions in the body

Structure

Physiological Role;

Action of Progesterone ON Control of ovulation

Progesterone prepares the endometrium for the potential of pregnancy after ovulation. It triggers the lining to thicken to accept a fertilized egg. It also prohibits the muscle contractions in the uterus that would cause the body to reject an egg.

Progesterone Action in the Breast

In the breast, progesterone acts in concert with estrogen to promote proliferative and pro-survival gene programs. In sharp contrast, progesterone inhibits estrogen-driven growth in the uterus and protects the ovary from neoplastic transformation.

Progesterone Effects in the Brain

the hormone most associated with happiness.Progesterone, on the other hand, can have a depressing effect.

Progesterone Effects on Bone

Progesterone seems to promote bone formation and/or increase bone turnover. It is possible, through estrogen-stimulated increased progesterone binding to the osteoblast receptor, that progesterone plays a role in the coupling of bone resorption with bone formation.

Antiestrogen Action of Progesterone

Antiestrogen action of progesterone in breast tissue. In normal breast, estrogen stimulates growth of the ductal system, while lobular development depends on progesterone

Disorders

INTRODUCTION;

After one of your ovaries releases an egg, your progesterone levels should rise. Progesterone helps the uterus thicken in anticipation of receiving a fertilized egg. If it’s not thick enough, the egg won’t implant.

CAUSES;

A high level of Estrogens can also result in reduced hormonal balance causing low levels of Progesterone. Well, the hormonal imbalance that causes low levels of Progesterone

SYMPTOMS

Symptoms of low progesterone in women who aren’t pregnant include:

·         headaches or migraines

·         mood changes, including anxiety or depression

·         irregularity in menstrual cycle

During pregnancy, symptoms of low progesterone include

·         spotting and miscarriage.

AFFECTED POPULATION

 Affects women of reproductive age, with an average age of onset in the late 20s among cases described in the literature.