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Glands (Pituitary (Hormones (Adenohypophysis (consists of (pars distalis…
Glands
Pituitary
Location
located in a bony cavity called sella tursica and is attached to hypothalamus by a stalk
Hormones
Adenohypophysis
regulated by hormones of hypothalamus through a portal circulation system
consists of
pars distalis
GH
PRL
regulates growth of mammary glands and formation of milk in them
TSH
stimulates the synthesis and secretion of thyroid hormones from the thyroid gland
ACTH
stimulates the synthesis and secretion of steroid hormones called glucocorticoids from the adrenal cortex
LH and FSH
stimulate gonadal activity and hence are called gonadotrophins
in males, LH stimulates the synthesis and secretion of hormones called androgens from testis.
In males, FSH and androgens regulate spermatogenesis
In females, LH induces ovulation of fully mature follicles (graafian follicles) and maintains the corpus luteum, formed from the remnants of the graafian follicles in females.
pars intermedia
MSH
Acts on the melanocytes (melanin containing cells) and regulates pigmentation of the skin
Pars intermedia is almost merged with pars distalis
Neurohypophysis
consists of pars nervosa
stores and releases
oxytocin
acts on smooth muscles of our body and stimulates their contraction.
In females, it stimulates a vigorous contraction of uterus at time of child birth, and milk ejection from the mammary gland.
vassopresin
acts mainly at the kidney and stimulates resorption of water and electrolytes by the distal tubules and thereby reduces loss of water through urine (diuresis). Hence, it is also called as anti-diuretic hormone.
oxytocin and vassopressin are actually synthesised by hypothalamus and are transported axonally to neurohypophysis
Oversecretion
GH
gigantism
abnormal body growth
Undersecretion
GH
pituitary dwarfism
stunted growth
Thyroid Gland
location
thyroid gland exists as two lobes of either side of the trachea connected by a thin flap of connective tissue, known as isthmus
hormones
tetreiodothyronine or thyroxine (T4)
triiodothyronine (T3)
Play an important role in regulation of the basal metabolic rate
hormones also support the process of red blood cell formation
control metabolism of carbohydrates, proteins and fats
maintenance of water and electrolyte balance is influenced by thyroid hormones
Thyrocalcitonin (TCT)
regulates blood calcium level
Diseases
Hypothyroidism
goitre
enlargement of thyroid gland
during pregnancy, causes defective development and maturation of the growing baby, leading to stunted growth (cretinism), mental retardation, low intelligence quotient, abnormal skin, deaf - mutism, etc.
In adult women, may cause menstrual cycle to become irregular
hyperthyroidism
rate of synthesis and secretion of thyroid hormones is increased to abnormal high levels leading to a condition
due to cancer of thyroid gland or development of nodules of the thyroid gland
adversely affects body physiology
Thymus
location
lobular structure located between lungs behind the sternum on the ventral side of the aorta
Hormones
secretes peptide hormones called thymosins
play major role in differentiation of T-lymphocytes, which provide cell mediated immunity
Also promote production of antibodies to provide humoral immunity
disorders ?
thymus is degenerated in old individuals resulting in decreased production of thymosins.
the immune responses of old persons become weak
Hypothalamus
Location
It is the basal part of the diencephalon, near the pituitary gland
Hormones
Releasing Hormones
GnRH
Inhibiting Hormones
Somatostatin
Pineal Gland
location
dorsal side of forebrain
hormones
melatonin
plays a very important role in the regulation of a 24 hour (diurnal) rhythm of our body
It helps in maintaining the normal sleep-wake cycle (circadian cycle), body temperature.
influences metabolism, pigmentation, menstrual cycle, and defense capability
Parathyroid gland
location
four parathyroid glands are present on the back side of the thyroid gland, one pair in each of the two lobes of the thyroid gland
hormone
parathyroid hormone (PTH)
secretion of PTH is regulated by the circulating levels of calcium ions.
increases Ca2+ levels in blood
acts on bones and stimulates the process of bone resorption (dissolution/demineralisation)
also stimulates reabsorption of Ca2+ by the renal tubules and increases Ca2+ absorption form the digested food
It is a hypercalcemic hormone
increases blood Ca2+ levels
Along with TCT, it plays a significant role in calcium balance in the body
Adrenal Gland
location
one at the anterior part of each kidney
Hormones
Adrenal medulla
catecholamines
noradrenaline or norepinephrine
adrenaline or epinephrine
adrenaline and noradrenaline are rapidly secreted in response to stress of any kind and during emergency situations and are called emergency hormones or hormones of fight or flight
increase alertness, pupillary dilation, piloerection (raising of hairs), sweating, etc.
both increase heart beat, strength of heart contraction and rate of respiration
also stimulate breakdown of glycogen, resulting in an increased concentration of glucose in the blood.
Also stimulate the breakdown of lipids and proteins.
Adrenal cortex
secretes corticoids
corticoids involved in carbohydrate metabolism are called glucocorticoids.
in our body, cortisol is the main glucocorticoid
involved in maintaining the cardiovascular system and the kidney functions
stimulates RBC production
stimulate glucogenesis, lipolysis and proteolysis
inhibit cellular uptake and utilisation of amino acids
glucocorticoids, particularly cortisol, produces anti- inflammatory reactions and suppresses the immune response.
corticoids which regulate the balance of water and electrolytes in our body are called mineralocorticoids.
Aldosterone is the main mineralocorticoid in our body
acts mainly at the renal tubules and stimulates reabsorption of Na+ and water and excretion of K+ and phosphate ions.
thus, aldosterone helps in maintenance of electrolytes, body fluid volume, osmotic pressure and blood pressure.
Also secretes small amounts of androgenic steroids
Pancreas
Location
The pancreas is in the abdominal cavity, behind the stomach
Hormones
Glucagon
secreted by alpha- cells
peptide hormone
plays important role in maintaining normal blood glucose levels
acts mainly on hepatocytes and adipocytes
enhances cellular glucose uptake and utilisation
there is rapid movement of glucose from blood to hepatocytes, resulting in decreased blood glucose levels, known as hypoglycemia
prolonged hyperglycemia leads to diabetes mellitus, which is associated with loss of glucose through urine and formation of harmful compounds known as ketone bodies
diabetic patients are treated with insulin therapy
Insulin
secreted by beta-cells
stimulates conversion of glucose to glycogen (glycogenesis) in target cells
Glucose homeostasis in blood is maintained jointly by glucagon and insulin.
Testis
location
in the scrotal sac outside the abdomen of male individuals
hormones
androgens
mainly testosterone
regulate the development, maturation and functions of the male accessory sex organs like epididymis, vas deferens, seminal vesicles, prostate gland, urethra, etc.
stimulate muscular growth, growth of facial and axillary hair, aggressiveness, low pitch of voice, etc.
play major stimulatory role in the process of spermatogenesis
act on the CNS and influence male sexual behaviour
produce anabolic effects on protein and carbohydrate metabolism
ovary
location
in abdomen
hormones
oestrogen
synthesised and secreted mainly by growing ovarian follicles
stimulation of growth and activities of female secondary sex organs, development of growing ovarian follicles, appearance of female secondary sex characters, mammary gland development.
regulate female sex behaviour
progesterone
corpus luteum mainly secretes this
supports pregnancy
acts on mammary glands and stimulates formation of alveoli and milk secretion
Hormones of the heart, kidney, and gastrointestinal tract
in tb