Flashcards: Endocrine System

What is the endocrine system composed of?

Groups of tissues that form organs

How do endocrine tissues release hormones?

They are ductless and release hormones directly into circulation.

What is a hormone?

A signaling molecule.

What are the three types of hormones?

Protein hormones, steroid hormones, modified amino acid hormones.

How do hormones function?

Travel to distant targets, interact with receptors, and create effects.

What do hormones control?

Biological processes and most tissues.

Is endocrine dysfunction common?

Yes.

Where are protein hormones produced?

In endocrine tissues via gene transcription.

What triggers protein hormone release?

Specific signals (e.g., insulin secretion with increased glucose).

Are protein hormones stored in large amounts?

Yes, for quick release.

How do protein hormones act on target cells?

Bind to cell surface receptors.

What happens if receptor mutations occur?

Diseases arise (e.g., inactivation or nonhormonal pathway activation).

What are steroid hormones derived from?

Cholesterol.

Where are steroid hormones produced?

Adrenal cortex, ovaries, testes.

Are steroid hormones stored in large amounts?

No, they are synthesized rapidly as needed.

Are steroid hormones hydrophobic or hydrophilic?

Hydrophobic; they easily pass through cell membranes.

How are steroid hormones transported in blood?

By carrier proteins.

How do steroid hormones act compared to protein hormones?

Slower onset but longer-lasting effects.

What are modified amino acid hormones derived from?

Tyrosine.

Give examples of modified amino acid hormones.

Thyroid hormones, epinephrine, norepinephrine.

How are modified amino acid hormones transported?

Via carrier proteins (mostly water-insoluble).

Where do modified amino acid hormones act?

Intracellular receptors.

What is the half-life of modified amino acid hormones?

Short (

What causes Cushing’s Syndrome in horses?

Pituitary Pars Intermedia Dysfunction (PPID) – adenoma of the pars intermedia.

How does Cushing’s affect the hypothalamus?

Alters body temperature, appetite, shedding.

What is the pathognomonic sign of Cushing’s in horses?

Long, curly hair coat.

What are other clinical signs of Cushing’s?

PU/PD, muscle weakness, abnormal fat distribution, increased infections.

How is Cushing’s diagnosed?

ACTH concentrations, blood cortisol response, thyrotropin-releasing hormone (TRH) test.

What is the treatment for Cushing’s?

Pergolide (dopaminergic receptor agonist), body hair clipping, supportive care.

Is hyperthyroidism in horses commonly misdiagnosed?

Yes.

What are the two types of hyperthyroidism?

Primary: Thyroid gland dysfunction; Secondary: Anterior pituitary dysfunction → low TSH.

What are clinical signs of hyperthyroidism in foals?

Weakness, poor suckling, fine hair coat, tendon laxity, low body temperature.

What are clinical signs of hyperthyroidism in adult horses?

Lethargy, low heart rate, obesity, laminitis, exercise intolerance.

How is hyperthyroidism diagnosed?

Thyroid hormone levels (unreliable), TRH response test, response to hormone supplementation.

What is the treatment for hyperthyroidism?

Thyroid hormone supplementation (weaning required).

What causes hypothyroidism in sheep/goats?

Iodine deficiency, thyrotoxic plants.

What happens when T3/T4 levels are low?

Increased TSH → thyroid gland enlargement.

What are the clinical signs of hypothyroidism in sheep/goats?

Poor wool quality, dry skin, tendon laxity, poor reproductive performance.

How is hypothyroidism diagnosed?

Clinical signs + low iodine levels.

What is the treatment for hypothyroidism?

Iodine supplementation.

What causes hyperparathyroidism?

Nutritional imbalance (Ca:P ratio), oxalate-rich plants, iatrogenic causes.

What hormone is involved in hyperparathyroidism?

Parathyroid hormone (PTH) → bone calcium resorption.

What are clinical signs of hyperparathyroidism?

Lameness, loose teeth, spontaneous fractures, inability to rise.

How is hyperparathyroidism diagnosed?

Radiographs, dietary analysis.

How is hyperparathyroidism treated?

Correct mineral imbalance, prevent with proper diet.