Anatomy Of Endocrine System PDF

Anatomy of Endocrine System D R. M USA R R AT  Endocrine system Endocrine glands are glands that secrete their products, hormones, directly into the blood. The endocrine system makes more the 20 major hormones that help control: Growth Reproduction Se...

Anatomy of Endocrine System D R. M USA R R AT  Endocrine system Endocrine glands are glands that secrete their products, hormones, directly into the blood. The endocrine system makes more the 20 major hormones that help control: Growth Reproduction Sexual development Use and Storage of energy Responses to physical stress or trauma Level of fluid salt and sugar in blood  MAJOR GLANDS OF ENDOCRINE SYSTEM The major glands of the endocrine system include the: Pineal gland Pituitary gland Pancreas Ovaries Testes Thyroid gland Parathyroid gland Hypothalamus Adrenal glands.  Hypothalamus Lies above the pituitary in the diencephalon of the brain. It regulates the hormonal output of the pituitary and creates two hormones that it exports to the posterior pituitary for storage and later release that are Oxytocin and Antidiuretic hormone (ADH) Hormone Main Function Stimulation of adrenocorticotropic hormone (ACTH) release from the Corticotropin-releasing hormone anterior pituitary Dopamine Inhibition of prolactin release from the anterior pituitary Stimulation of luteinizing hormone (LH) and follicle-stimulating Gonadotropin-releasing hormone hormone (FSH) release from the anterior pituitary Growth-hormone-releasing hormone Stimulation of growth hormone (GH) release from the anterior pituitary Oxytocin Stimulation of uterine contractions and milk ejection Somatostatin Inhibition of growth hormone (GH) release from the anterior pituitary Thyrotropin-releasing hormone Stimulation of thyroid-stimulating hormone (TSH) from the anterior pituitary Vasopressin (antidiuretic hormone) Increase reabsorption of free water in the renal tubules  Pituitary Gland Hangs from the base of the brain by the pituitary stalk, and is enclosed by bone (sphenoid bone). The gland is divided into: i. Anterior lobe (Adenohypophysis): it is the true gland, Secretes hormones ii. Posterior lobe (Neurohypophysis): connected to hypothalamus through hypothalamo-hypophyseal tract, Stores hormones secreted by hypothalamic nuclei  Hormones Produced by the Pituitary Gland  Hormone Secreted from Function Adrenocorticotrophic hormone Anterior pituitary Stimulates the adrenal cortex to release (ACTH) corticosteroids Thyroid-stimulating hormone Anterior pituitary Promotes normal development and activity of (TSH) the thyroid gland Luteinizing hormone (LH) Anterior pituitary Regulate the functions of the gonads in both sexes. Follicle-stimulating hormone Anterior pituitary Regulate the functions of the gonads in both (FSH) sexes. Prolactin (PRL) Anterior pituitary Promotes milk production in human females Growth hormone (GH) Anterior pituitary Stimulates growth of all body tissues especially skeletal Oxytocin Posterior pituitary Have a potent contractile activity on the pregnant uterus and functions during lactation. Vasopressin Posterior Pituitary Regulate blood pressure, blood osmolality, and blood volume.  Pineal Gland The pineal gland is located in the diencephalon of the brain. It is a midline, ovoid structure that measures approximately 8 × 4 mm in size.  It primarily releases melatonin which is a sleep- inducing hormone, in response to varied circadian rhythms sensed by the hypothalamus. The pineal gland and hypothalamic nuclei help regulate the sleep−wake cycle.  Thyroid Gland The thyroid gland is located at the front of the neck, in front of the thyroid cartilage, and is shaped like a butterfly, with two wings connected by a central isthmus. Secretes T3 and T4 which control the Basal Metabplic Rate (BMR), Influence cell differentiation and growth.  Parathyroid Gland Four parathyroid gland are found near the posterior aspect of the thyroid gland. They are small 20 -40 mg and have a bean like shape. They secrete parathyroid hormone (PTH) which help to maintain calcium homeostasis by acting on the renal tubule as well as calcium store in the skeletal system and by acting indirectly on the gastointestinal tract through the activation of Vitamin D.  Adrenal Glands The adrenal gland is a small tri angular gland located on top of the kidney. The gland consist s of a medulla and is surrounded by cortex.  The adrenal glands produce a variety of hormones including adrenaline and the steroids (aldosterone and cortisol).  Gland Region/cells Hormones Functions Adrenal cortex Mineralocorticoids Regulate salt and water (Zona glomerulosa) (aldosterone) balance in the body Adrenal cortex Glucocorticoids (cortisol) Suppress immune (Zona fasciculate) response and regulate carbohydrate metabolism Adrenal cortex Weak androgens Precursor for testosterone (Zona reticularis) (dehydroepiandrosterone) production Adrenal medulla Catecholamines Increase heart rate, (Chromaffin cells) (epinephrine and nor- respiration, blood pressure. epinephrine)  Pancreas Gland with both exocrine and endocrine functions. Located in epigastric and left hypochondric region. Retro-peritoneum. Parts of pancreas are head, neck, body and tail Hormones Secreted From Pancreas  Ovaries The ovaries are the female pelvic reproduction organ and are responsible for the production of sex hormones. The ovaries are small and paired organ located on either side of the uterus. Hormones produce by the ovary are estrogen and progesterone. (Secretion of estrogens by the ovarian follicles begins at puberty under the influence of FSH. Progesterone is released in response to high blood levels of LH).  Testes Testes are the male gonads, located in the scrotum. The testes of the male begin to produce testosterone at puberty in response to LH.  Other Hormones Many body organs not normally considered endocrine organs contain isolated cell clusters that secrete hormones. Examples include Heart (atrial natriuretic peptide; regulate blood pressure) Gastrointestinal tract organs (gastrin, secretin, and others; stimulate release of secretions in response to food) The placenta (hormones of pregnancy—estrogen, progesterone, and others; promote implantation and gestation) The kidneys (erythropoietin and renin; play role in production of RBCs and regulation of blood pressure respectively) Adipose tissue (leptin and resistin; regulating weight and glucose metabolism).