Question

1. Define homeostasis. Who was the first person to describe the phenomenon? Who was the first person to coin the term Homeostasis. Explain the processes involved in returning your body temperature to its 37°C set point during a run when your body temperature gets above 37°C.

2. As you are sitting at your desk reviewing ANS 100 lectures during Spring 2020, you look out your window and notice a new species of animal. You remember reading about this new species Covidicus whoknowswhatitis on social media and that people don’t know much about it yet. So, like a good Animal Science student you go outside to take a closer look. You see that there are lots of individuals of this species and they range in size from about 1g to 1000g. They are transparent and so you can see their internal organs (and you have superpowers, so you know the weight of everything you look at!). You notice that one individual is 10g and has a 1g liver, you then notice another individual that is 30g and has a 3 g liver. In this species, does liver size scale allometrically or isometrically? Both animals turn around and now you see their kidneys. In the 10g species the kidney is 0.5g (yes, they have big kidneys) and in the 30g species the kidney is 1g. In this species, does the kidney scale allometrically or isometrically? Explain the difference between allometric and isometric scaling. Why do many physiological processes or anatomical structures scale allometrically?

3. You are taking a nice walk through the Arboretum to get some fresh air and you notice a salmon in Putah Creek. You decide that you must return this salmon to the ocean. When you reach into Putah Creek you notice how warm the water is (15°C). When you release the salmon in the ocean at UC Davis’s Bodega Marine Lab the seawater feels quite cold (5°C). What is the body the temperature of the salmon in Putah Creek and what is the body temperature of the salmon in the ocean? You were able to take a blood sample and measure plasma chloride levels of the salmon when it was in Putah Creek and then again after you returned it to the ocean. Was the plasma chloride ion concentration higher in the salmon after you returned it to the ocean because seawater has a higher chloride concentration? Lastly, would you classify the salmon as a conformer or a regulator or does it depend? Briefly describe your answer.

4. You are an undergraduate honors student in my lab and you just came home from doing field work in the Antarctic (water temperature -1.9°C) with frozen fish muscle tissue. You are interested in learning more about adaptation to temperature so you also go to Putah Creek (water temperature = 15°C) and collect muscle tissues from another salmon you find. You put both bags of fish tissue in the freezer but forget to label them. What aspect of cellular physiology could you examine to determine which species came from water at -1.9°C and which species came from water at 15°C? What specifically would you look for to assign the fish tissues to one group or the other?

5. So, you go back to the Bodega Marine Lab after the shelter in place order has been lifted (i.e. many weeks from now) and go fishing, because, who doesn’t like to fish! The water is still very cold (5°C), so you decide swimming is a bad idea. You catch the same salmon you released from Putah Creek back in Question 3. You eat it for dinner but also take a sample of its muscle. You run it through the same set of tests you did in Question 4. What do you find and how does it compare to the salmon you caught in Putah Creek in Question 4?

6. We see beautiful Wilson warblers at Putah Creek during our fish collection. Because we have the animal care permits, we need, we collect these birds and hold them at the same two temperatures as the salmon (i.e. 5°C and 15°C). Would we expect to see the same changes as we saw in fish? Why or Why not?

7. Many different molecules need to pass in and out of a cell across the cell membrane and from the outside of the body to the inside. Some of these molecules are hydrophobic and some are hydrophilic. Define these two terms and explain why they differ in their ability to pass through cell membranes. What part of a cell membrane makes it so tricky for some molecules to get through? How do these two types of molecules pass through cell membranes?

Answer 1

HOMEOSTASIS :-

• Homeostasis is the physiological process by which the internal system of the body ( e.g. blood pressure , blood glucose , body temperature ) are maintained at equilibrium despite variation in the external condotion .
• In other words , homeostasis means " same state " . Refers to the process of keeping the internal body environment in a steady state , when the external environment is changed .

The concept of the regulation of the internal environment was described by french physiologist Claude Bernard in 1849 and the word homeostasis was coined by Walter bradford Cannon in 1926 .

NAGATIVE FEEDBACK LOOP FOR HOMEOSTASIS OF TEMPERATURE :-

• 
• when person is stressed out , a large amount of heat is produced . This heat is accumulates in the body , causing a rise in blood temperature . This change is detected by hypothalamus , causing it to send out nerve impulses to the relevent body parts .
• Nerve impulses effects on skin , dilation of blood vessels of the skin .And blood flow to the skin is increased .
• sweat glands becomes more active , resulting in more sweat being producing . As more water evaporates from the sweat on the skin surface , more heat is lost .
• Body temperature may lowers and stress is reduced causing shutting down the mechanism .

HYDROPHOBIC MOLECULES :-  

• Nonpolar molecules that repel the water molecules are said to be hydrophobic molecules .
• In other words , water hating molecules are said to be hydrophobic molecules.

HYDROPHILIC MOLECULES :-

• Molecules forming ionic or a hydrogen bonding with the water molecules are said to be hydrophilic molecule.
• In other words , water loving molecules are said to be hydrophilic molecule .