Chapter 1. Chapter 25: Overview of Physiology

1.1 Introduction

Welcome to the Interactive Study Guide for Chapter 25: Overview of Physiology! This Study Guide will help you master your understanding of the chapter's Driving Questions, using interactive Infographics and activities, as well as targeted assessment questions. Click "Next" to get started, or select a Driving Question from the drop-down menu to the right.

DRIVING QUESTIONS

• How are the bodies of living organisms organized?
• How do humans and other organisms regulate body temperature?
• What physiological systems are regulated by homeostatic feedback loops?

1.2 Driving Question 1:

Why should you care?

Your anatomy is made up of different kinds of cells that form tissues, which form organs, which form organ systems, which form your body. Understanding the organization of your body and the parts involved is a crucial part of understanding your health.

What should you know?

To fully answer this Driving Question, you should be able to:

1. Describe the relations among cells, tissues, organs, and organ systems.
2. Describe examples of various types of cells and tissues.

Infographic Focus

The Infographic most pertinent to the Driving Question is 25.1.

1.3 Driving Question 2:

Why should you care?

Your home has features like thermostats, air conditioners, pressure regulators, water heaters, and insulation that all work to maintain constant conditions in it. Just like a house, your body maintains relatively constant conditions in several ways. Many diseases, for example diabetes, result from faulty regulation of conditions in the body. Knowing about homeostasis—how the body maintains a constant state—can help us understand how to take better care of our own health.

Your body uses several processes to maintain a constant body temperature. When the outside temperature is extremely cold, the body works to maintain a constant internal temperature by conserving the heat it has and generating additional heat. When the outside temperature is extremely hot, the body also works to maintain a constant internal temperature by expelling heat and sweating. Learning about thermoregulation will give you insight into how organ systems in your body work cooperatively to maintain homeostasis.

A feedback loop is a cyclic pathway of sensing and effecting that works to regulate something in the body. When that something is body temperature, the sensing is done by thermosensors, special nerves in outer layers of the skin, and the effecting is done by muscles and blood vessels. Learning about how body temperature is regulated could help you avoid behaviors that will lead to either hypothermia or overheating. For example, alcohol is often suggested as a means to warm up in cold weather, but it actually works as a vasodilator, bringing more blood to the skin, where it initially makes a person feel warmer but will quickly lead the blood to cool as it gives off its heat.

What should you know?

To fully answer this Driving Question, you should be able to:

1. List the conditions that the human body keeps relatively constant to maintain homeostasis.
2. Explain the various processes involved in maintaining a constant body temperature in response to cold and heat.
3. Identify the components and processes involved in the feedback loop that is responsible for thermoregulation in humans.

Infographic Focus

The Infographics most pertinent to the Driving Question are 25.2 to 25.4.

List the conditions that the human body keeps relatively constant to maintain homeostasis.

Question 1.7

Without looking at Infographic 25.2, list some of the conditions in the human body that are kept relatively constant in healthy people. Then refer to Infographic 25.2 and fill in any conditions you might have missed.

Why is it important for the body to regulate these conditions? Fill in your answers next to the conditions.

Condition Maintained at a Constant Level in the Body	Reason It Is Important to Maintain This Condition Constant
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Condition Maintained at a Constant Level in the Body	Reason It Is Important to Maintain This Condition Constant
Body temperature	Proteins (including enzymes) can function only in a small window of optimal temperature.
Blood pH	Proteins (including enzymes) can function only in a small window of optimal pH.
Blood Pressure	If your blood pressure is too low, not enough blood will get to your brain and organs. If your blood pressure is too high, you may rupture a vein or artery.

Incorrect.

1.4 Driving Question 3:

Why should you care?

Feedback loops in your body continually survey and measure various elements inside and outside of your body to maintain optimal functioning of your organ systems and therefore your body as a whole. Maintaining homeostasis is important, as even a slight tip in that balance in either direction could have dire consequences for your overall health. Two examples of homeostatic feedback loops are the loop that maintains blood glucose levels and the loop that regulates the pressure, solute concentration, and water concentration of your blood.

What should you know?

To fully answer this Driving Question, you should be able to:

1. Describe the components and processes in the feedback loop that is responsible for blood glucose level regulation in humans.
2. Describe the components and processes in the feedback loop that is responsible for osmoregulation in humans.
3. Explain what happens when glucose levels and osmolarity are not well regulated.

Infographic Focus

The Infographics most pertinent to the Driving Question are 25.5 and 25.6.

Describe the components and processes involved in the feedback loop that is responsible for blood glucose level regulation in humans.

Question 1.16

Examine Infographic 25.5 and answer the following questions.

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1. Pancreas releases glucagon into the blood.
2. Liver and muscle cells break down stored glycogen into glucose.

Question 1.17

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1. Pancreas releases insulin into the blood.
2. Liver and muscle cells take in and store glucose as glycogen.

Question 1.18

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When you are not consuming enough food.

Question 1.19

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organ: liver; tissue: muscle; storage molecule: glycogen

Question 1.20

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pancreas

Question 1.21

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Hormone 1: Insulin signals body cells to take in glucose, which will be used as a source of energy, and signals liver and muscle cells to take in glucose and store it as glycogen.
Hormone 2: Glucagon signals liver and muscle cells to break down stored glycogen to release glucose in the bloodstream.