Homeostasis

Question 1

What series of events occur when metabolic rate falls?

Answer 1

• Hypothalamus detects fall and releases more thyrotropin releasing hormone
• Causes pituitary gland to release more thyroid stimulating hormone
• Causes thyroid gland to release more thyroxine
• Causes metabolic rate of cells to increase

Question 2

What events occur when body temperature increases?

Answer 2

• Thermoreceptors in hypothalamus detects this
• Sweating increases (water has a high heat capacity) , shunt vessels close and vasodilation occurs so blood flow to skin surface increases
• Erector pili muscles relax and body hair lies flat

Question 3

What events occur when body temperature falls?

Answer 3

• Hypothalamus detects this
• Shunt vessels open and vasoconstriction occurs so blood flow to skin surface decreases
• Erector pili muscles contracts and body hair stands up to provide an insulating layer
• Shivering caused by rapid contraction of muscles
• Metabolic rate increases

Question 4

Why is it important that endotherms maintain constant internal temperatures?

Answer 4

• So that their internal temperature is kept close to the optimum for their enzymes.