Homeostasis and Regulation Mechanisms

Homeostasis

• Homeostasis maintains internal regulation via negative feedback loops.
• Key control systems include thermoregulation, osmoregulation, and blood glucose regulation.

Thermoregulation

• Endothermic animals like horses maintain a constant body temperature (37.5°C).
• Hypothalamus detects blood temperature changes.
• Cooling Mechanisms: Dilation of blood vessels near the skin, sweating, behavioral changes (seeking shade, water). Hairs lay flat.
• Warming Mechanisms: Constriction of blood vessels near the skin, shivering, piloerection (hair standing on end). Release of internal fats.

Blood Glucose Regulation

• Negative feedback loop regulates blood glucose levels.
• High Blood Glucose: Pancreas releases insulin to store glucose.
• Low Blood Glucose: Liver releases glycogen, produces glucose 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: veins, arteries, capillaries, blood, heart.
• Capillaries: Thin walls for nutrient exchange and waste removal.
• Veins: Transport blood to the heart, contain valves to prevent backflow. (Largest- vena cava)
• Arteries: Transport oxygenated blood, thick walls; (e.g., pulmonary artery). Layers: tunica adventitia (outer), tunica media (middle), tunica intima (inner).
• Blood Composition: Erythrocytes (red blood cells), plasma, platelets, leukocytes (white blood cells).
• Platelets: Crucial for blood clotting.
• Heart: 4 chambers (right and left ventricle, right and left atrium). Pumps blood throughout the body. (4kg in a horse)
• Vena Cava transports deoxygenated blood to the heart.
• Aorta transports oxygenated blood.

Cushing's Disease (PPID)

• Cause: Endocrine dysfunction due to pituitary pars intermedia dysfunction, dysregulation of hormones. Dopamine, which regulates other hormones, decreases.
• Diagnosing: Clinical signs (hypertrichosis, weight loss, increased infections, laminitis, frequent urination) and ACTH blood test.
• Treatment: Prascend medication (FDA-approved). Preventative supplements:
  • Nutritional: Increased amino acids (lysine, methionine, threonine), antioxidants, Omega-3 fatty acids, adaptogens.
• Insulin resistance assessment: Oral sugar tolerance test.
• Management: Reduce sugar and starch intake (reduced grain, grazing muzzles, soaked hay). Reduce treats. Use laminaze supplements.