Homeostasis Quiz

Homeostasis

• Homeostasis maintains internal conditions through negative feedback loops.
• Mechanisms include thermoregulation, osmoregulation, and blood glucose regulation.
• Thermoregulation: Horses (endotherms) maintain a body temperature of 37.5°C.
  • If body temperature drops, the hypothalamus triggers negative feedback mechanisms: shivering, vasoconstriction (constricted blood vessels), piloerection (hair standing up), and fat mobilization for heat production.
  • If body temperature rises, the body responds with vasodilation (dilated blood vessels), piloerection reduction, sweating, and behavioral adjustments (seeking shade, water).
• Blood Glucose Regulation: Pancreas cells detect glucose levels.
  • High blood glucose: Insulin release to store glucose, prevent fat production.
  • Low blood glucose: Glycogen release from the liver, glucose synthesis from amino acids.
• Osmoregulation: Regulates water and electrolyte balance in the body.

Circulatory System

• Transports nutrients, waste, oxygen, carbon dioxide, hormones.
• Regulates pH and temperature.
• Components: Heart, blood vessels (arteries, veins, capillaries), blood.
  • Capillaries: One cell thick for nutrient/hormone exchange and gas exchange.
  • Veins: Carry blood to the heart; often have valves to prevent backflow.
  • Arteries: Carry blood away from the heart; multiple layers forming thick walls to withstand pressure.
  • Blood: Contains erythrocytes (red blood cells), plasma, platelets, and leukocytes (white blood cells).
    • Platelets: Essential for blood clotting.
    • Erythrocytes: Transport oxygen.
  • Heart: 4 chambers (right/left atrium and ventricle)
    • Horse heart: ~4kg; deoxygenated blood travels to lungs, oxygenated blood returns to the heart, then to the body.

Cushing's Disease (PPID)

• Endocrine disorder caused by pituitary gland dysfunction (often due to age and oxidative stress).
• PPID: Dopamine deficiency leading to ACTH overproduction.
• Clinical Signs: Hypertrichosis (excessive hair), weight loss, increased susceptibility to infections and laminitis, frequent urination
• Diagnosis: Clinical signs and blood ACTH test.
• Treatment: Prascend (medication).
• Management: Dietary adjustments (reduce sugar/starch), supplements:
  • Amino acids (lysine, methionine, threonine) for topline development
  • Antioxidants
  • Omega-3 fatty acids for inflammatory balance
  • Adaptogens to help the immune system.
• Additional Testing: Oral sugar tolerance test can identify insulin resistance to further tailor the management plan.