PHYSIOLOGY

• What is homeostasis?

  Regulation of the body's internal environment
• What does the term "homeo" mean in homeostasis?

  Similar
• What does the term "stasis" mean in homeostasis?

  Balance
• What are examples of homeostasis?

  Thermoregulation, blood pressure, blood glucose
• What happens if internal conditions go above or below the normal range?

  You can get sick
• How does the heartbeat illustrate homeostasis?

  It relies on coordinated contractions of cardiac muscle
• What governs the contractions of cardiac muscle cells?

  Electrical signals (action potentials)
• What ions are crucial for cardiac muscle cell function?

  Sodium and potassium ions
• What happens if there is excess potassium outside cardiac muscle cells?

  Muscle cells become less excitable
• What is the effect of too little potassium outside cardiac muscle cells?

  Heart beats erratically
• What do negative feedback loops do?

  Counteract changes or stimuli
• What are the components of homeostasis?

  • Stimulus: Change in the environment
  • Receptor: Detects the change
  • Control center: Decides what to do
  • Efferent signal: Sent away from control center
  • Afferent signal: Sent to control center
  • Effector: Acts on changes needed
• What do positive feedback loops do?

  Amplify a response to a stimulus
• What is the normal range for internal body temperature?

  36-37 degrees Celsius
• What happens when cold temperatures stimulate thermoreceptors?

  Afferent signals are sent to the CNS
• What does the hypothalamus do in response to cold temperatures?

  Sends efferent signals to blood vessels and muscles
• What is the response of blood vessels to cold temperatures?

  Vasoconstrict to retain heat
• What happens to muscles in response to cold temperatures?

  They shiver to produce heat
• What happens when hot temperatures stimulate thermoreceptors?

  Afferent signals are sent to the hypothalamus
• What does the hypothalamus do in response to hot temperatures?

  Sends efferent signals to effector organs
• What is the response of blood vessels to hot temperatures?

  Vasodilate to increase blood flow
• What is the role of sweat production in hot temperatures?

  Allows for evaporative cooling
• What is a positive feedback loop?

  • Self-amplifying cycle
  • Physiological change leads to greater change
  • Example: Childbirth, breastfeeding, platelet plug formation
• What triggers the positive feedback loop during childbirth?

  Stretching of the cervix
• What do stretch receptors in the uterus do during childbirth?

  Send afferent signals to the hypothalamus
• What hormone is released during childbirth to stimulate contractions?

  Oxytocin
• What is the stimulus for the positive feedback loop in breastfeeding?

  Suckling
• What happens as the uterus contracts during childbirth?

  Further stretches the cervix
• What do mechanoreceptors around the breast do during breastfeeding?

  Send signals to the hypothalamus
• What hormone stimulates milk production during breastfeeding?

  Prolactin
• What hormone allows for milk ejection during breastfeeding?

  Oxytocin
• What is the stimulus for the positive feedback loop in platelet plug formation?

  Hole or tear in the blood vessel
• What initiates the blood coagulation cascade?

  External damage to the vasculature
• What is a feedforward system?

  • Anticipates changes in controlled variables
  • Takes action to mitigate errors
  • Example: Maintaining balance while walking
• What happens if homeostasis fails?

  Ill health and medical issues arise
• What is fluid balance?

  Regulation of water and electrolyte balance
• What triggers thirst in the body?

  Loss of 2-3% body water
• What happens to mental performance at 1% dehydration?

  It starts to become impaired
• What organs regulate fluid balance in the body?

  Brain, adrenal glands, kidneys
• What is the role of the gastrointestinal tract in fluid balance?

  Responsible for absorption of water