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Name: _________________________________________ Sec : _________ Date: ________________________________

Lab 30: Maintaining Homeostasis

Objective: In this lab, students will be able to identify the different ways that organisms perform regulation.

Introduction: Throughout the school year, we have taken a close look at the different life processes that are necessary to the survival of organisms. Each of the processes plays a role in maintaining homeostasis for organisms. Homeostasis is necessary in order to keep organisms happy and healthy. This means that all of their levels are balanced and in order. Any time homeostasis is disrupted, it can result in disease, sickness, or even death. In the lab, we will look at the different ways that the human body can regulate itself in order to stay happy and healthy.

Comprehension Questions:

1. Define homeostasis: _______________________________________________________________________________

2. Explain why each of the life processes below help to maintain homeostasis.

a. Transport: _________________________________________________________________________________

b. Nutrition: _________________________________________________________________________________

c. Respiration: _______________________________________________________________________________

d. Excretion: _________________________________________________________________________________

e. Synthesis: _________________________________________________________________________________

3. What happens when homeostasis fails? _______________________________________________________________

Part A: Taking out the Trash

The process of excretion is important in maintaining homeostasis, because without it, all the wastes from digestion, respiration, and everything else would build up inside our body. Our bodies need to be able to get rid of all the bad stuff. There are several body parts that make up the excretory systems. The materials we get rid of are excess water and waste chemicals.

Comprehension Questions:

1. The picture below represents the organs involved in the excretory system. In the list below are the things that our body removes. Determine which organs are involved in the removal of each waste.

a. Sweat: ____________________________________________________

b. Urine: _____________________________________________________

c. Feces: _____________________________________________________

d. Carbon Dioxide: _____________________________________________

2. How do cells get rid of their wastes? ________________________________

3. How do plants get rid of their wastes? _______________________________

Part B: Getting the Message

The nervous system is a very important and is responsible for sending information to all parts of the body. The main organs that make up the nervous system are the brain and nerves. The brain sends messages to the body via nerve cells (also known as neurons) which release nerve signals. The cells of each organ of the body has receptors on its surface that are specific to each of the signals. When a stimulus is presented, your brain responds by sending chemical messages to the rest of your body.

Comprehension Questions:

1. Which organs make up the nervous system? _________________________________________________________

2. If nerve signals are square shaped. Draw the nerve cell receptors on the picture of the nerve cell below.

3. Fight or Flight Response.

a. Name something you are afraid of. __________________________ . (This is a stimulus)

b. What happens to your body when you encounter this thing? (Think about your heart and lungs)

1. _____________________________________________________________

2._____________________________________________________________

c. What do you think caused your body to respond that way? _______________________________________

d. Which organs were involved in your response?_________________________________________________

e. What is the name of the chemical messenger produced? _________________________________________

( HINT: This is sometimes called an _______________ rush when you are excited, angry or scared)

f. Why do you think this process is called the fight or flight response? ________________________________

_________________________________________________________________________________________

4. How do you think the nervous system is related to regulation and maintaining homeostasis? __________________

______________________________________________________________________________________________

Part C: I don’t feel so good.

The immune system is the most intricate and intense system of our bodies. It protects us from all the nasty stuff in the outside world that is out to get us. The things that we need to watch out for are called pathogens. Pathogens are things like parasites, bacteria, viruses and fungus. When a pathogen enters our body, it comes in ringing bells and sirens so our body knows it doesn’t belong. The warning signs of pathogens are called antigens. They are on the surface of their cells. Once the white blood cells notice these cells, they begin to produce antibodies. The shapes of the antibodies are specific to the shape of the antigens present. This enables them to locate the pathogens easily. When the antibodies find the pathogens they destroy them in a process called phagocytosis (they become like a pac man cell and engulf the intruder) The antibodies we produce during this response will remain in our bodies for a long time, this is called immunity.

1. Define the following:

a. pathogen: _______________________________________________________________________________

b. antigen: _________________________________________________________________________________

c. antibodies: _______________________________________________________________________________

d. white blood cells: __________________________________________________________________________

` e. phagocytosis: _____________________________________________________________________________

2. Describe each of the steps involved in the immune response.

a. Pathogen enters the body.

b. ___________________ recognize foreign ____________ on the surface of _________________.

c. ___________________ produce _______________ that are programmed to search and destroy.

d. ___________________ locate __________________ and perform ____________________ to kill them.

e. Antibodies remain in the body for a long time, in case of future attacks.

3. When a vaccine is given to humans, they contain a weakened pathogen that cannot harm them. Why do doctors use vaccines to create immunity to different diseases that humans are exposed to?

__________________________________________________________________________________________________

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4. Every cell of our body has specific proteins , when foreign cells come into your body with different proteins (the antigens) our body immediately rejects them. Why do doctors give patients immune system suppressing drugs before they receive blood or organ transplants?

__________________________________________________________________________________________________

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Part D: Feeling a bit hormonal.

The endocrine system consists of glands and hormones that travel through your blood stream in order for different parts of the body to communicate. Just like nerve signals, hormones are also referred to as chemical messengers. When something in your body changes, hormones are released through feedback mechanisms in order to restore the body back to normal. Some examples of glands that secrete hormones are the testes which secrete testosterone and the ovaries which secrete progesterone and estrogen. These hormones regulate the reproductive cycles of man and women respectively. Hormones are not only related to reproduction though, they sometimes help us respond to danger (like the adrenaline in the fight or flight response), they regulate our metabolism, and they help determine brain function.

1. Define: chemical messengers (hormones):_____________________________________________________________

2. What are some ways that our body is regulated by hormones?

a. _________________________________________________________________________________________

b. _________________________________________________________________________________________

c. _________________________________________________________________________________________

3. The insulin response is one of the most well known functions of the endocrine system. When we eat carbohydrates, after digestion and absorption, the level of glucose in our blood goes up. Our pancreas responds by producing insulin. The insulin then travels through the blood to the liver, which produces another hormone called glucagon, this tells the body to start using the glucose in the cells for energy. Diabetic people do not have the ability to make insulin, and so they cannot produce this response and so they must take shots of insulin daily in order to break down sugar in their body and use it for energy.

1. Fill in the cycle below with each of the steps that take place in the insulin response.

2. What causes diabetics not to be able to produce the protein insulin? (Think back to genetics) ____________________

__________________________________________________________________________________________________

3. What types of food would trigger the immune response? (Think back to nutrition) _____________________________

4. Why is it necessary for us to be able to get glucose into our cells? (Think back to respiration) _____________________

__________________________________________________________________________________________________

5 . How do small molecules like glucose get into our cells? Why can’t starch get into our cells?(Think back to transport)

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