Lp 17 endocrinology 2009

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Endocrinology Hopefully made easy!

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Transcript of Lp 17 endocrinology 2009

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Endocrinology

Hopefully made easy!

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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

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Introduction/General Info

Major Endocrine Glands- Pituitary Thyroid glands Parathyroids Pancreas Ovaries Testes Adrenal glands

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The Pituitary Gland

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Pituitary Gland

Divided into 2 lobes, each of which acts as a separate gland. Anterior Posterior

Mainly influenced by the Hypothalamus.

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Anterior Pituitary Gland

“Master Endocrine Gland” Develops from glandular tissue.

Hormones-1. Growth Hormone (GH)-

Promotes body growth Regulates metabolism Encourages protein synthesis

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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

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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.

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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.

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Posterior Pituitary Gland

Develops from the nervous system.

Does not produce any hormones.

Stores ADH & Oxytocin

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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.

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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.

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The Thyroid Gland

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The Thyroid Gland

Produces: Thyroid hormones

T3- has 3 iodine atoms

T4- has 4 iodine atoms Calcitonin

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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.

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The Adrenal Glands

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The Adrenal Glands…

Actually 2 glands- Adrenal

cortex Adrenal

medulla

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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.

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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.

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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.

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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.

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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.

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The Pancreas

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The Pancreas…

Controls metabolism Secretes:

1. Somatostatin- inhibits the secretion of insulin & glucagon.

2. Insulin- glucose 3. Glucagon- glucose

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Pathology

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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.

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Hyperthyroidism…

Signs include: Weight loss Polyphagia Vomiting Increased appetite Tachycardia (with or without

murmurs)

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Hyperthyroidism…

Treatment options include: Surgical removal of the

thyroid gland Radioactive iodine treatment Antithyroid drug therapy

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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.

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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.

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Adrenal Cortex

Hyperadrenocorticoidism- “Cushing’s Disease” Produced by excess cortisol

from the adrenal cortex. Hypoadrenocorticoidism-

“Addison’s Disease” Hypofunctioning of the adrenal

cortex.

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Pancreas

Hyperinsulinism- Excess secretion of insulin

causing hypoglycemia. A problem of ferrets. Etiology may be a pancreatic

tumor or an overdose of insulin.

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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.

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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.

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Laboratory Analysis

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Lab Analysis…

Glucose tolerance Thyroid tests- T3, T4, Free T4,

TSH ACTH Stim. Dexamethasone Suppression-

LDDS HDDS

Urine Cortisol : Creatinine

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THE END!