lp 17 endocrinology 2009
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Endocrinology
Hopefully made easy!
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
Introduction/General Info
Major Endocrine Glands- Pituitary Thyroid glands Parathyroids Pancreas Ovaries Testes Adrenal glands
The Pituitary Gland
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 (ACTH)-
Stimulates the growth and development of the adrenal cortex
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 Thyroid Gland
The Thyroid Gland
Produces: Thyroid hormones
T3- has 3 iodine atoms
T4- has 4 iodine atoms Calcitonin
Parathyroid Glands
Produces parathyroid hormone (PTH)
Works opposite to calcitonin to maintain blood calcium levels.
Mobilizes calcium from bones to the bloodstream. Negative feedback loop.
The Adrenal Glands
The Adrenal Glands…
Actually 2 glands- Adrenal
cortex Adrenal
medulla
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, & Corticosteronea. 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 ovaries & testes.
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” response.
The Adrenal Glands… Adrenal Medulla…1. Epinepherine-
heart rate, dilates bronchioles, and stimulates the production of glucose for energy.
2. Norepinepherine- Constricts blood vessels and
raises blood pressure.
The Pancreas
The Pancreas…
Controls metabolism Secretes:
1. Somatostatin- inhibits the secretion of insulin & glucagon.
2. Insulin- glucose 3. Glucagon- glucose
Pathology
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 body.
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.
Laboratory Analysis
Lab Analysis…
Glucose tolerance Thyroid tests- T3, T4, Free T4,
TSH ACTH Stim. Dexamethasone Suppression-
LDDS HDDS
Urine Cortisol : Creatinine
THE END!