Introduction/General Info Endocrine glands- secrete hormones. Exocrine glands- produce secretions that are released via ducts. Hormones- chemical messengers carried by plasma. Regulates the activity of the target organ. Not all hormones are secreted by endocrine glands, some are produced in tissue from another organ. Like EPO – produced by kidney
Pituitary Gland Divided into 2 lobes, each of which acts as a separate gland. Anterior Posterior Mainly influenced by the Hypothalamus.
Anterior Pituitary Gland “Master Endocrine Gland” Develops from glandular tissue. Hormones-1. Growth Hormone (GH)- Promotes body growth Regulates metabolism Encourages protein synthesis
Anterior Pituitary Gland…2. Prolactin (PRL)- Triggers and maintains lactation.3. Thyroid-stimulating Hormone (TSH)- Stimulates the growth and development of the thyroid gland.4. Adrenocorticotropic Hormone
Anterior Pituitary Gland…5. Follicle-stimulating Hormone (FSH)- Stimulates the growth & development of the ovarian follicles. Stimulates the follicle lining to produce & secrete ESTROGEN. Stimulates spermatogenesis.
Anterior Pituitary Gland…6. Luteinizing Hormone (LH)- Completes the follicle development process. Can cause OVULATION. Can cause the development of the CORPUS LUTEUM- Which produces PROGESTERONE, which maintains pregnancy. Can stimulate the testes to develop & produce TESTOSTERONE.
Posterior Pituitary Gland Develops from the nervous system. Does not produce any hormones. Stores ADH & Oxytocin
Posterior Pituitary Gland…1. Antidiuretic Hormone (ADH)- Prevents diuresis- Conserves water Urine is more concentrated The release of ADH is inhibited by alcohol and caffeine.
Posterior Pituitary Gland…2. Oxytocin- Has 2 targets- The uterus & mammary glands Can cause uterine contractions to: Aid in the transport of sperm to the oviducts. Aid in the delivery of the fetus.
The Adrenal Glands… Adrenal Cortex- Develops from glandular tissue. Under the influence of ACTH, it produces steroids: Glucocorticoids Mineralocorticoids Sex hormones Chemicals derived from cholesterol.
The Adrenal Glands… Adrenal Cortex…1. Glucocorticoids- Cortisone, Cortisol, & Corticosterone a. Cortisol- aka hydrocortisone, influences the metabolism of sugars and has a anti-inflammatory effect. b. Cortisone- similar to Cortisol, and can be prepared synthetically. Useful in treating inflammatory conditions. Causes a hyperglycemic effect. Causes blood glucose levels to rise.
The Adrenal Glands… Adrenal Cortex…2. Mineralocorticoids- Regulates electrolyte levels. The primary one is ALDOSTERONE. Reabsorbs sodium, excretes potassium.3. Sex Hormones- Androgens- male Estrogens- female Maintain secondary sex characteristics (beard & breast development) These hormones are also produced in
The Adrenal Glands… Adrenal Medulla- Develops from nervous tissue. Produces (catecholamines): Epinepherine Norepinepherine Chemicals derived from amino acids Along with the sympathetic nervous system, these catecholamines stimulate the “Fight or Flight”
The Adrenal Glands… Adrenal Medulla…1. Epinepherine- heart rate, dilates bronchioles, and stimulates the production of glucose for energy.1. Norepinepherine- Constricts blood vessels and raises blood pressure.
Hyperthyroidism The most commonly seen endocrine disorder in cats. Very rare in dogs except as a result of neoplasia. Bilateral thyroid gland enlargement occurs in 70% of cases.
Hyperthyroidism… Signs include: Weight loss Polyphagia Vomiting Increased appetite Tachycardia (with or without murmurs)
Hyperthyroidism… Treatment options include: Surgical removal of the thyroid gland Radioactive iodine treatment Antithyroid drug therapy
Hypothyroidism Commonly seen in the dog. Clinical signs include: Weight gain with no change in diet. Bilateral symmetric alopecia & loss of hair on the tail (“rat tail”). 66-75% of dogs will have an increased cholesterol level.
Parathyroid Hyperparathyroidism- production of parathormone. Causes hypercalcemia. Etiology is often a parathyroid tumor. Hypoparathyroidism- production of parathormone. Causes hypocalcemia. This leads to a condition called tetany- Constant muscle contraction.
Adrenal Cortex Hyperadrenocorticoidism- “Cushing’s Disease” Produced by excess cortisol from the adrenal cortex. Hypoadrenocorticoidism- “Addison’s Disease” Hypofunctioning of the adrenal cortex.
Pancreas Hyperinsulinism- Excess secretion of insulin causing hypoglycemia. A problem of ferrets. Etiology may be a pancreatic tumor or an overdose of insulin.
Pancreas Diabetes mellitus- Lack of insulin secretion or resistance of insulin to promote sugar, starch, and fat metabolism in cells. Symptoms include: PU/PD, glucosuria, and +/- ketoacidosis. Ketoacidosis- fats are improperly burned leading to an accumulation of ketones in the
Pancreas Type I Diabetes- Insulin-dependant diabetes mellitus (IDDM) Onset is usually in young animals. A complete deficiency of insulin. Patients require injections of insulin for treatment. Type II Diabetes- Non-insulin-dependant diabetes mellitus (NIDDM) A separate disease from type I. Still has a deficiency of insulin. Usually in older, obese animals. Treatment is with diet and oral medications.