Homeostasis

• What is positive feedback?

  A response that amplifies a detected change
• How does oxytocin function during childbirth?

  It causes contractions to aid delivery
• What is negative feedback?

  A response that reverses a detected change
• What is the role of negative feedback in homeostasis?

  It returns the body to homeostasis
• What are the steps in regulating glucose concentration when levels are higher than normal?

  1. Insulin produced by beta cells
  2. Insulin travels in blood to target cells
  3. Glucose uptake by cells increases
  4. Glucose converted to glycogen
• What are the steps in regulating glucose concentration when levels are lower than normal?

  1. Glucagon produced by alpha cells
  2. Glucagon travels in blood to target cells
  3. Glucagon binds to liver cell receptors
  4. Glycogen converted to glucose
• What is Type 1 diabetes?

  An autoimmune disease damaging beta cells
• What happens in Type 1 diabetes?

  The body no longer produces insulin
• How is Type 1 diabetes managed?

  Blood sugar monitoring and insulin injections
• What is a benefit for Type 1 diabetes patients?

  A healthy diet can improve management
• What characterizes Type 2 diabetes?

  Insulin produced but receptors don't respond
• What causes insulin resistance in Type 2 diabetes?

  Excess body weight and lack of exercise
• How can Type 2 diabetes be prevented?

  By maintaining a healthy diet
• Why do insulin injections not work in Type 2 diabetes?

  Target cells are resistant to insulin
• What triggers hyperthermia?

  Warm thermoreceptors sending signals
• What is the hypothalamus's response to hyperthermia?

  It reduces thyroxin secretion
• What physiological changes occur during hyperthermia?

  Decreased metabolic rate and vasodilation
• What triggers hypothermia?

  Cold thermoreceptors sending signals
• What is the hypothalamus's response to hypothermia?

  It increases thyroxin secretion
• What physiological changes occur during hypothermia?

  Increased metabolic rate and shivering
• What is uncoupled respiration in brown adipose tissue?

  Energy released is transformed into heat
• What happens to hair erector muscles during hypothermia?

  They contract to trap heat
• What is selective reabsorption in the kidneys?

  • Sodium ions actively transported out
  • Chloride ions passively transported out
  • Glucose and amino acids cotransported with sodium
  • Water reabsorbed via osmosis
• What are the characteristics of the Loop of Henle?

  • Descending loop: permeable to water, impermeable to salts
  • Ascending loop: impermeable to water, permeable to salts
  • Functions as a countercurrent system
• What is the role of ADH in the collecting duct?

  It increases permeability to water
• How does ADH affect urine concentration?

  Urine becomes more concentrated
• When does ADH secretion stop?

  When osmolarity returns to normal
• What happens to metabolic rate during sleep?

  It is low during sleep
• How does the parasympathetic nervous system affect blood flow during sleep?

  It changes blood flow to decrease muscle supply
• What happens to blood flow to the brain and kidneys during sleep?

  Blood supply remains constant
• What happens to blood flow during vigorous activity?

  Increased blood flow to muscles occurs
• How does the sympathetic nervous system affect blood flow during vigorous activity?

  It increases blood flow to muscles
• What is the blood flow status during wakeful rest?

  Balanced parasympathetic and sympathetic activity
• How does blood flow to muscles during wakeful rest compare to sleep?

  It is low but more than during sleep
• What happens to blood flow to the gut during wakeful rest?

  Blood flow remains stable
• What is the blood flow status to the brain during wakeful rest?

  It remains constant
• What happens to blood flow to the kidneys during wakeful rest?

  Blood flow remains stable