Tag Archives: endocrine system

The Hypothalamus and Pituitary Gland, with Animation.

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The hypothalamus and the pituitary gland are at the center of endocrine function. The hypothalamus is part of the brain, while the pituitary, also called hypophysis (hy-POFF-ih-sis), is an endocrine gland. The hypothalamus links the nervous system to the endocrine system via the pituitary gland. The two structures are located at the base of the brain and are connected by a thin stalk.

The hypothalamus produces several hormones, known as neurohormones, which control the secretion of other hormones by the pituitary. Pituitary hormones, in turn, control the production of yet other hormones by other endocrine glands.

The pituitary has two distinct lobes:

The anterior pituitary, also called adenohypophysis (AD-eh-no-hy-POFF-ih-sis), communicates with the hypothalamus via a network of blood vessels known as the hypophyseal portal system. Several neurohormones produced by the hypothalamus are secreted into the portal system to reach the anterior pituitary, where they stimulate or inhibit production of pituitary hormones. Major hormones include:

Gonadotropin-releasing hormone, GnRH, a hypothalamic hormone, stimulates the anterior pituitary to producefollicle-stimulating hormone, FSH, and luteinizing hormone, FSH and LH, in turn, control the activities of the gonads – the ovaries and testes.
Corticotropin-releasing hormone, CRH,promotes the secretion of adrenocorticotropic hormone, ACTH, which in turn stimulates production of cortisol by the adrenal gland.
Thyrotropin-releasing hormone, TRH, promotes the release of thyroid-stimulating hormone, TSH, and prolactin. TSH, in turn, induces the thyroid gland to produce thyroid hormones. Prolactin stimulates the mammary glands to produce milk.
Prolactin-inhibiting hormone, PIH, inhibits production of prolactin.
Growth hormone–releasing hormone, GHRH, promotes production of growth hormone, or somatotropin, which has widespread effects on the growth of various tissues in the body.
Growth hormone–inhibiting hormone, GHIH, or somatostatin, inhibits production of growth hormone.

The posterior pituitary, also called neurohypophysis, communicates with the hypothalamus via a bundle of nerve fibers. These are essentially hypothalamic neurons with cell bodies located in the hypothalamus while their axons EXTENDED to posterior pituitary. These neurons produce hormones, transport them down the stalk, and store them at the nerve terminals within the posterior pituitary, where they wait for a nerve signal to trigger their release. Two hormones have been identified so far:

– Vasopressin, also known as antidiuretic hormone, ADH, acts on the kidneys to retain water.

– Oxytocin causes the uterus to contract during childbirth and stimulates contractions of the milk ducts in lactating women.

Heart, Blood and Circulation Gallery

Download illustrations of human circulatory system: gross anatomy, cardiac cycle, heart diseases and congenital defects, cardiovascular conditions and surgery treatment, blood cell formation, vascular disorders, and more.

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Blood flow in vessel, medical drawing.

Red blood cells streaming in artery

Elements of blood, medical drawing.

Illustration of red and white blood cells, lymphocytes, monocytes, platelets, basophil, eosinophil, neutrophil.

Atherosclerosis, unlabeled.

Blood clot forms on cholesterol plaque in artery blocking blood flow.

Atherosclerosis, labeled.

Blood clot forms on cholesterol plaque, blocked artery.

Process of cholesterol plaque in artery, unlabeled

Diagram showing process of cholesterol plaque in artery, unlabeled version.

Stages of Atherosclerosis

Process of cholesterol plaque build-up in artery, labeled diagram.

Leukemia versus normal blood count, illustration.

Cancer of blood, Anemia, medical drawing.

Brain stroke diagrams

Ischemic versus Hemorrhagic brain stroke, unlabeled.

Blood supply to the brain diagram

Lateral view of the brain with middle cerebral artery, unlabeled.

Stages of atherosclerosis diagram

Cholesterol plaque build-up in blood vessel and formation of blood clot cause blockage of blood flow, labeled.

Clipart of healthcare icon (cardiology)

Magnifying glass on an ECG graph diagram

Cardiac arrhythmias ECG/ EKG set diagram.

Normal and pathological electrocardiograms in heart diseases.

EKG and myocardium function diagram

Phases of electrical activity of human heart, ECG cycle.

Myocardial infarction diagram (heart attack)

Coronary artery blocked by cholesterol plaque causing heart stroke.

Human heart blood flow

Illustration of blood flow through the heart, labeled

Human heart blood flow

Illustration of blood flow through the heart, unlabeled

Blood supply to the heart unlabeled diagram

Coronary arteries illustration, anterior view of the heart

Blood supply to the heart labeled diagram

Coronary arteries illustration, anterior view of the heart

Human heart cut, medical illustration.

Heart anatomy diagram, unlabeled.

Left ventricular hypertrophy labeled diagram

Thickening of the myocardium of left ventricle of human heart.

Electrical pathways of the heart, unlabeled

The cardiac conduction system of human heart, unlabeled version.

Heart valves operation, unlabeled diagram.

Cycles of heart valves operation pumping blood through different chambers, aorta and veins.

Electrical pathways of the heart

The cardiac conduction system of human heart, labeled version.

Abdominal aortic aneurysm diagram

Aneurysm in aorta of the abdomen and bleeding risk.

Deep vein thrombosis diagram

Abnormal blood clotting in deep leg vein and formation of thrombus.

Tetralogy of Fallot diagram

Congenital heart disease: Tetralogy of Fallot, labeled

Ventricular septal heart defect diagram.

Congenital heart disease: ventricular septal defect, hole in the septum between ventricles, unlabeled.

Balloon angioplasty procedure diagram

Heart cath procedure with balloon to widen artery with plaque

Heart and lungs diagram unlabeled

Human lungs and heart anatomy, unlabeled.

Thorax anatomy unlabeled diagram.

Human heart cross section and lungs anatomy.

Biofeedback regulation of heart rate, medical illustration.

Regulation of blood pressure through baroreflex, unlabeled version.

Biofeedback regulation of heart rate, labeled.

Regulation of blood pressure through baroreflex, labeled version.

Blood supply to the head and neck, labeled drawing.

Diagram of human head anatomy with arteries including internal carotid supplying the brain, lateral (side) view, labeled.

Blood supply to the brain, coronal section.

Middle cerebral artery anatomy and distribution, labeled diagram.

Metastatic cancer, medical drawing.

Cancer cell squeezes through the endothelium of blood and lymph vessel, illustration unlabeled.

Human circulatory system diagram

Anatomy of human circulation system, unlabeled.

Endocrine System Gallery

Download diagrams illustrating anatomy of endocrine organs, hypothalamus and pituitary gland, steroid and non-steroid hormones actions, signaling pathways, endocrine disorders.