The Great Communicator Chapter 11 The Great Communicator

Functions of the Endocrine System The endocrine system is composed of ductless glands that secrete chemical messengers called hormones into the bloodstream. Endo- means within. -crine means to secrete or separate.

Functions of the Endocrine System Hormones enter the bloodstream and are carried throughout the body to affect a variety of tissues and organs.

Structures of the Endocrine System The glands of the normal endocrine system: one pituitary gland one thyroid gland four parathyroid glands two adrenal glands one pancreas one thymus one pineal gland two gonads 4

The Pituitary Gland The pituitary gland is located at the base of the brain just below the hypothalamus. The hypothalamus secretes releasing and inhibiting factors that affect the release of substances from the pituitary gland. The combining form for the pituitary gland is pituit/o. The pituitary gland has two lobes: anterior and posterior.

Pituitary Gland Controls all other glands Located within the sphenoid bone of the skull Divided into 2 lobes Anterior lobe Posterior lobe

The Anterior Pituitary Gland Secretions of the anterior pituitary gland: thyroid stimulating hormone (TSH) adrenocorticotropic hormone (ACTH) follicle-stimulating hormone (FSH) luteinizing hormone (LH) interstitial cell-stimulating hormone (ICSH) prolactin growth hormone (GH) melanocyte-stimulating hormone (MSH) 7

Anterior Lobe Growth Hormone (Somatropin) Thyroid Stimulating Hormone (TSH) Gonadotropic Hormones Ovaries Follicle stimulating hormone (estrogen) Luteinizing Hormone : formation of corpus luteum Testes Follicle stimulating hormone (development of sperm cells) Luteinizing Hormone : testosterones Prolactin (mammary gland development)

Adrenocorticotropic Hormone (ACTH) Adrenal glands Production of corticosteriods Melanocyte stimulating hormone (MSH) melanin pigment in skin and hair Involved in ability to undergo chameleonlike color changes

The Posterior Pituitary Gland Secretions of the posterior pituitary gland: antidiuretic hormone (ADH) oxytocin 10

Posterior Lobe Antidiuretic hormone (ADH) Oxytocin Limits development of large volume of urine by reabsorbing water by kidneys Oxytocin Stimulates milk production and contraction of uterus during parturition

The Thyroid Gland The thyroid gland is a butterfly-shaped gland that secretes the following: triiodothyronine (T3) thyroxine (T4) calcitonin The combining forms for the thyroid gland are thyr/o and thyroid/o.

Thyroid Gland Regulates growth and metabolism Over or under production of iodine Calcitonin maintains balance of calcium in the blood by decreasing In birds causes molting and other behaviors linked to Changes in daylight.

January 7, 2015 From memory - List the names of the glands belonging to the Endocrine System: 1. 2. 3. 4. 5. 6. 7. 8.

The Parathyroid Glands The parathyroid glands are usually four glands located on the surface of the thyroid gland. The parathyroid glands secrete parathormone. The combining form for the parathyroid glands is parathyroid/o.

Parathyroid Gland “Near” thyroid gland / 2 on each side Parathyroid Hormone (PTH) Regulates calcium Maintains balance of calcium in blood by decreasing

The Adrenal Glands The adrenal cortex secretes The adrenal glands are two glands located cranial to each kidney; they consist of a cortex and a medulla. Ad- means toward. Ren/o means kidney. The adrenal cortex secretes mineralocorticoids glucocorticoids and androgens (sex hormones) .

Adrenal Glands The adrenal medulla secretes epinephrine (adrenoline) and norepinephrine The combining forms for the adrenal glands are adren/o and adrenal/o.

The Pancreas The pancreas is a gland located near the proximal duodenum that has exocrine and endocrine functions. The endocrine functions of the pancreas maintain blood glucose levels. The pancreas secretes insulin and glucagon. The combining form for the pancreas is pancreat/o.

Pancreas Insulin Glucagon Use and storage of carbohydrates (sugar) Decrease blood glucose levels Glucagon Increase blood glucose levels

The Thymus The thymus is a gland predominant in young animals located near midline in the cranioventral portion of the thoracic cavity. The thymus secretes thymosin which is responsible for production of white blood cells (T- lymphocyte cells) / immunity In adulthood becomes fatty piece of tissue

The Pineal Gland The pineal gland is located near midline in the central portion of the brain and functions in maintaining circadian rhythm. The pineal gland secretes melatonin. Resemble pinecone The combining form for the pineal gland is pineal/o.

The Gonads The gonads are glands that produce gametes (sex cells). The gonads are the ovaries in females and the testes in males. The combining form for the gonads is gonad/o.

The Ovaries The ovaries are the female gonads. Secretions of the ovaries: estrogen progesterone . 24

The Testes The testes are the male gonads. Secretion of the testes: testosterone 25

Hyperadrenocorticism Over production of glucocorticoid (hormone) Commonly called Cushings Disease An opposite disease is Addison’s where there is a deficiency Signs: Polydypsia Polyuria Body fat distribution

Pathological Conditions

Hyperthyroidism Common in aging cats Excessive production of thyroid hormone Can feel an enlarged thyroid gland Can be treated with medication Surgical removal of the thyroid gland

Signs of Hyperthyroidism Weight loss (increased metabolism) Polyuria Polydipsia Meowing Aggression Affection (Behavior changes)

Diabetes Mellitus Insulin is hormone that transports blood glucose to be stored (as glycogen)and used for energy needs of cells Pancreas doesn’t produce insulin, too much glucose in blood Results in low pH of blood (acid) Ketoacidosis = low blood pH and ketones (which are by products of fat metabolism)

Ketoacidosis is result of no production of insulin = blood glucose (“sugar”) Hypoglycemic is the opposite and is the result of overdose of insulin!

Things to remember about diabetes Signs of diabetes: Often overweight Middle aged – senior Breed predisposition Cats Polydipsia Polyuria Sudden weight loss cataracts

Things to remember Too much insulin can kill Diabetes can be treated but not cured: balancing between too much insulin and too little insulin difficult for owners to understand initially treatment is lifetime Too much insulin can kill Too little can result in death also

Medical Terms for the Endocrine System Additional terms for endocrine system tests, pathology, and procedures can be found in the text. Review StudyWARE to make sure you understand these terms.