Endocrine System

Functions of Hormone

1. Help regulate: • Chemical composition and volume of internal environment (interstitial fluid). • Metabolism and energy balance. • Contraction of smooth and cardiac muscle fibers. • Glandular secretions. • Some immune system activities. 2. Control growth and development. 3. Regulate operation of reproductive systems. 4. Help establish circadian rhythms.

Antidiuretic Antidiuretic Hormone Hormone ( ADH)

Causes kidneys to reduce water excretion, In high concentration, raises blood pressure Hypothalamus produces and neurosecretory cells in the posterior pituitary release ADH in response to blood water concentrations and blood volume

Tail of pancreas

It is located at the Abdomen (left upper quadrant), it is posterior to stomach and tip of tail adjacent to spleen. It is the elongated part of the pancreas gland. In the endocrine system (regulation of glucose metabolism): the pancreatic islet cells release hormones (insulin, glucagon, and somatostatin) into blood. and in the exocrine (digestion): the acinar cells produce digestive enzymes (pancreatic juice) and pancreatic duct cells produce bicarbonate ions; these are released into duodenum via pancreatic ducts. The reduction in insulin production or release by pancreatic islet cells can result in diabetes mellitus.

Head of pancreas

It is located at the abdomen (right upper quadrant and it's adjacent to duodenum. the head of the pancreas is a "C" shape conforms to duodenum, it's contains junction of bile and it's the main pancreatic ducts that form hepatopancreatic ampulla.In the endocrine system (regulation of glucose metabolism): the pancreatic islet cells release hormones (insulin, glucagon, and somatostatin) into blood. and in the exocrine (digestion): the acinar cells produce digestive enzymes (pancreatic juice) and pancreatic duct cells produce bicarbonate ions; these are released into duodenum via pancreatic ducts. The reduction in insulin production or release by pancreatic islet cells can result in diabetes mellitus.

Suprarenal capsule

It's Surrounds suprarenal (adrenal) gland, it's a connective tissue Also known as: Adrenal capsule

Stress

Physical Stress - extreme heat or cold, decreased oxygen, infection, injury, heavy exercise, loud sound Psychological Stress - feelings of fear, anger, grief, depression, guilt - even pleasant stimuli may be stressfu

Luteinizing Hormone ( LH or ICSH in men, glycoprotein gonadotropin)

Promotes secretion of sex hormones, In women, promotes egg release, Gonadotropin-releasing hormone from the hypothalamus stimulates secretion

Growth Hormone (GH)

Stimulates increase in size and mitotic rate of body cells, increases fat utilization, Enhances amino acid movement through membranes and promotes protein synthesis, Promotes long bone growth, Growth hormone releasing hormone (GHRH) stimulates secretion and Somatostatin (SS) inhibits secretion

Control of Hormone Secretion

The hypothalamus controls the anterior pituitary through release of tropic hormones (stimulate other endocrine glands) Glands can respond directly to changes in the composition of the internal environment The nervous system can stimulate glands

Hormone

is a biochemical cell secretes into interstitial fluid that travels in the blood and acts on target cells.

Hormonal communication

it's generally begins with a part of the neuroendocrine system receiving sensory information and reacting by issuing a command to the body in the form of hormone. When hormone molecules reach target cells, they will bind to matching receptors on those cells and the hormone- receptor complexes will trigger changes in the target cells, this causes the kidney to reduce the urine volume output, and this increases water retention and countering dehydration. In the blood vessels, the vasoconstriction is increased and this leads to higher blood pressure.

Ovary

it's located at the Pelvis (lateral wall), near distal end of uterine tube and extends into lower abdominal quadrants. it is a paired, female gonad, with an Almond shape and size Contains oocytes (egg). it's responsible for Maturation (oogenesis) and release (ovulation) of oocytes. it's produces the female sex hormones progesterone, estrogen, and inhibin. its suspended by mesovarium of broad ligament (a peritoneal fold) and suspensory ligament of ovary (a peritoneal fold) contains ovarian vessels and nerves.Size decreases after menopause

Autocrine Substances

they are substances secreted into the interstitial fluid but only act on the same cell.

Follicle Follicle-stimulating Hormone stimulating Hormone (FSH, glycoprotein gonadotropin)

Development of ovarian follicles, stimulates follicular cells to secrete estrogen, In men, stimulation of sperm production, Gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates secretion

Response to Stress

General stress (or adaptation) syndrome, Hypothalamus receives stimuli evoked by all types of stress, Fight-or-Flight response activated via sympathetic nervous system and adrenal medulla, CRH is released from the hypothalamus to stimulate ACTH release, ACTH stimulates cortisol release from the adrenal cortex.

Oxytocin ( OT)

Contracts muscles in uterine wall and those associated with milk-secreting glands, Produced by the hypothalamus and secreted by neurosecretory cells in the posterior pituitary in response to uterine and vaginal wall stretching and stimulation of breasts

Adrenocorticotropic Hormone (ACTH)

Controls secretion of hormones from the adrenal cortex, Corticotropin-releasing hormone (CRH) from the hypothalamus stimulates secretion , Stress can stimulate CRH secretion

Thyroid Thyroid-stimulating Hormone stimulating Hormone (TSH/Thyrotropin

Controls secretion of hormones from the thyroid gland, Thyrotropin-releasing hormone (TRH) from the hypothalamus stimulates secretion and High levels lead to goiter

Suprarenal medulla

it is located at the central part of suprarenal (adrenal) gland. it's reddish-brown, core of gland and composed primarily of chromaffin cells. its produces epinephrine (adrenaline) and norepinephrine (noradrenaline) that work with sympathetic nervous system in "fight-or-flight" responses. it is also known as Adrenal medulla

Prolactin (PRL)

Sustains milk production after birth, Decreases LH secretion in men, Secretion stimulated by prolactin-releasing hormone from the hypothalamus and Secretion inhibited by prolactin-inhibiting hormone from the hypothalamus

Pituitary gland:

it is located at the Mid line of middle cranial fossa and rests in hypophysial fossa of sphenoid bone. it is a Small, oval bilobed endocrine gland and has Two functional lobes: anterior (adenohypophysis) and posterior (neurohypophysis). it is connected by infundibulum to hypothalamus. The Anterior pituitary produces the following hormones: thyroid-stimulating (TSH), prolactin (PRL), adrenocorticotropic (ACTH), growth (GH), luteinizing (LH), melanocyte-stimulating (MSH), and follicle-stimulating (FSH) and the Posterior pituitary stores and releases: antidiuretic hormone (ADH) and oxytocin (OT). Posterior pituitary does not produce any hormones; ADH and OT produced in hypothalamus and the pituitary gland is also known as: Hypophysial gland or hypophysis.

Suprarenal gland

it is located at the Abdomen (upper quadrants) and it's adjacent to superior pole of kidney. it's has a Paired, pyramidal-shaped, endocrine gland and it's didvded in two parts: cortex (outer) and medulla (inner). The cortex: secretes hormones (corticosteroids and androgen) and the Medulla: chromaffin cells secrete catecholamines (epinephrine and norepinephrine). its also known as: Adrenal gland and the Epinephrine and norepinephrine are also known as adrenaline and noradrenaline

Pineal gland

it is located at the Diencephalon (epithalamus). It is a Pea-sized endocrine gland that is attached to the roof of third ventricle. its Secretes melatonin ( which is involved in sleep/wake cycles), its modified activity in endocrine organs (pituitary, pancreas, parathyroid, suprarenal, and gonads).they are also known as: Pineal body

Isthmus of thyroid gland

it is located at the Mid-line of thyroid gland. it is the narrow connection between lateral lobes and pyramidal lobe.its Synthesizes and secretes thyroid hormones T3 (triiodothyronine) and T4 (thyroxine) and also Synthesizes and secretes calcitonin

Body of pancreas

it is located at the Pancreas, it is found between neck and tail of pancreas.In the endocrine system (regulation of glucose metabolism): the pancreatic islet cells release hormones (insulin, glucagon, and somatostatin) into blood. and in the exocrine (digestion): the acinar cells produce digestive enzymes (pancreatic juice) and pancreatic duct cells produce bicarbonate ions; these are released into duodenum via pancreatic ducts. The reduction in insulin production or release by pancreatic islet cells can result in diabetes mellitus. the splenic artery and vein course along superior border.

Nonsteroid Hormones

Amines, peptides, and proteins combine with receptors on the target cell membrane. Hormones bind at receptor binding sites. The activity site of the receptor interacts with other membrane proteins. Receptor binding can trigger a cascade of biochemical activity (second messengers).

Thyroid gland

It is located at the neck (anterior inferior). It is a bilobed endocrine gland that is normally composed of left and right lateral lobes that are connected across the mid-line by isthmus of gland. it's follicular cells: synthesize and secrete thyroid hormones T3 (triiodothyronine) and T4 (thyroxine) and it's Parafollicular cells: synthesize and secrete calcitonin. its lobes lie lateral to trachea and larynx,an enlarged thyroid gland is known as a goiter, and it is typically due to insufficient dietary iodine.

Hypothalamus

It is located at the ventral diencephalon, it's collects nuclei located inferior to thalamus, and this Includes the infundibulum and mammillary bodies.it's function as a master control center for endocrine system, it's secretes , releases and inhibit hormones that control anterior pituitary gland. It's produces hormones that are transported to and stored in posterior pituitary gland. it also controls autonomic nervous system and regulates body temperature, food, and water intake, Regulates emotional behavior and Maintains sleep/wake cycle.

Infundibulum of pituitary gland

It is located at the ventral surface of diencephalon (hypothalamus) at the mid-line. its conntains hypothalamo-hypophysial tract and hypothalamo-hypophysial portal vein that carries hypophysiotropic hormones to the anterior pituitary. its main function is to Transmits antidiuretic hormone (ADH) and oxytocin through hypothalamo-hypophysial tract to posterior pituitary. infundibulum means a funnel in latin.

Pancreas

It is located in the Abdomen and it's Posterior to the stomach, in the upper abdominal quadrants and in the epigastric region and left hypochondriac region (tail). The pancreas is a accessory digestive organ and a elongated nodular gland that is divided into head, neck, body, and tail. The head is adjacent to duodenum.In the endocrine system (regulation of glucose metabolism): the pancreatic islet cells release hormones (insulin, glucagon, and somatostatin) into blood. and in the exocrine (digestion): the acinar cells produce digestive enzymes (pancreatic juice) and pancreatic duct cells produce bicarbonate ions; these are released into duodenum via pancreatic ducts. The reduction in insulin production or release by pancreatic islet cells can result in diabetes mellitus.

Pyramidal lobe of thyroid gland

It's extends superiorly from isthmus, it is a Pyramidal extension of gland. it's synthesizes and secretes thyroid hormones T3 (triiodothyronine) and T4 (thyroxine) and also Synthesizes and secretes calcitonin.

Surface projection of thyroid gland

It's is located at the Neck (anterior inferior) is a bilobed endocrine gland that composed of pyramidal and lateral lobes that is connected across mid-line by isthmus of gland. it's synthesize and secrete thyroid hormones T3 (triiodothyronine) or T4 (thyroxine)., it's also Synthesize and secrete calcitonin.

Suprarenal cortex

It's located at the Outer part of suprarenal (adrenal) gland. It's a Lipid-rich, yellowish outer part of the suprarenal gland. it's divided into three regions: zonula glomerulosa, zonula fasciculata, and zonula reticularis. The Zonula glomerulosa produces mineralocorticoids (e.g., aldosterone) that regulate sodium/potassium ratio in blood and body fluids, the Zonula fasciculata produces glucocorticoids (e.g., cortisol) that stimulate lipid and protein metabolism, and regulate blood glucose levels and the Zonula reticularis produces steroid sex hormones called gonadocorticoids (e.g., dehydroepiandrosterone or DHEA). Also known as: Adrenal cortex and the disorders of suprarenal cortex hormone secretion include Addison's disease and Cushing's syndrome.

Testis

It's located at the Scrotum, it's a Paired, oval, male gonad, it's has a dense outer capsule (tunica albuginea testis) it's Interior is divided into 200-300 lobules and each lobule contains up to three seminiferous tubules. it's main function is to produce sperm cells and androgens (male sex hormones) such as testosterone. The testis begins development near the kidney, and later descends along the posterior abdominal wall to the scrotum Development of sperm cells is temperature dependent (scrotal temperature ~3° lower than body cavity) Temperature of testis regulated by: (1) distance from body cavity, and (2) heat exchange between testicular artery and pampiniform venous plexus Testosterone regulates hair pattern, sperm production, skeletomuscular growth, and libido

Steroid Hormones

They are soluble in the lipids of the cell membrane. Easily diffuse into target cells. Combine with specific protein receptors. Hormone-receptor complex binds to a specific region of DNA and activates genes. The mRNA directs synthesis of a particular protein. The protein brings about cellular changes.

Endocrine Secretion

They secrete their products (hormones) into the interstitial fluid surrounding the secretory cells rather than into ducts. From the interstitial fluid, hormones diffuse into blood capillaries and blood carries them to target cells throughout the body.

Exocrine Secretion

They secrete their products into ducts that carry the secretions into body cavities, into the lumen of an organ, or to the outer surface of the body. Exocrine glands include sudoriferous (sweat), sebaceous (oil), mucous, and digestive glands.

Neck of pancreas

it is located between the head and body of the pancreas.In the endocrine system (regulation of glucose metabolism): the pancreatic islet cells release hormones (insulin, glucagon, and somatostatin) into blood. and in the exocrine (digestion): the acinar cells produce digestive enzymes (pancreatic juice) and pancreatic duct cells produce bicarbonate ions; these are released into duodenum via pancreatic ducts. The reduction in insulin production or release by pancreatic islet cells can result in diabetes mellitus.

Lateral lobe of thyroid gland

it is located by the Lateral and anterior to trachea and larynx. It's has a paired, elongated, lateral extensions from isthmus. its Synthesizes and secretes thyroid hormones T3 (triiodothyronine) and T4 (thyroxine) and also Synthesizes and secretes calcitonin

Paracrine Substances

they are substances secreted into the interstitial fluid but acts on cells other than the endocrine cell that produced them.

Actions/ Activities of hormone

they reach all cells but bind only to those that have specific receptors, their receptors are protein or glycoproteins with a hormone binding site, they bind to the receptor, the more receptors , the greater the response.