Homeostasis

Question 1

What is homeostasis?

Answer 1

maintenance of stable internal conditions within an organism despite external changes

Question 2

Contrast the 3 strategies of escape, conform, or regulate. Give examples.

Answer 2

1. when severe conditions: hibernation, aestivation/dig into ground (lungfish), cryptobiosis/pause metabolic activities (water bear)
2. (marine invertebrates)
3. behavioral/hot? = go to shade (iguana), physiological/cold? = raise metabolism and shiver (most mammals), and osmoregulation (freshwater)

Question 3

Identify a hypo- or hyperosmotic fish from a description or diagram

Answer 3

• Hypothermic: body is more water so draw water out cause need to conserve
• Hyperthermic: saltier body so water comes in (bye bye)

Question 4

Explain or identify homeostasis regulation by negative feedback. What is positive feedback?

Answer 4

• negative: counteracts
  -ex: too salty: kindey releases Na+ –> brain dont want salt no more –> thirst –> drink water –> kidney releases ADH hormones that retain the water
• positive: amplifies responses and
  processes, typically used in situations needing a rapid, decisive outcome like blood clotting

Question 5

How do endocrine and nervous systems compare in scale to the other mechanisms of chemical signaling? How do the endocrine and nervous systems contribute to
homeostasis?

Answer 5

The endocrine system uses hormones for long-lasting effects, while the nervous system uses neurotransmitters for rapid, short term responses.

Question 6

Why is the anterior pituitary called the “master gland”?

Answer 6

controls the functions of several other hormone-secreting glands in the body.

Question 6

Why is iodide added to salt, and vitamin D added to milk? Under what circumstances might you not get enough of each of these nutrients?