Chapter One Guyton

Question 1

What is physiology?

Answer 1

The science that seeks to explain the physical and chemical mechanisms responsible for the origin, development, and progression of life.

Question 2

What are the subdivisions of physiology?

Answer 2

• Viral physiology
• Bacterial physiology
• Cellular physiology
• Plant physiology
• Invertebrate physiology
• Vertebrate physiology
• Mammalian physiology
• Human physiology

Question 3

What does human physiology explain?

Answer 3

The specific characteristics and mechanisms of the human body that make it a living being.

Question 4

What drives the complex control systems in human physiology?

Answer 4

Hunger, fear, sensations of cold, and the need for fellowship and reproduction.

Question 5

What is the basic living unit of the body?

Answer 5

The cell.

Question 6

How many human cells are estimated to be in the body?

Answer 6

About 35 to 40 trillion.

Question 7

What functions do red blood cells perform?

Answer 7

Transport oxygen from the lungs to the tissues.

Question 8

What are microbiota?

Answer 8

Communities of microorganisms that inhabit the body.

Question 9

What is extracellular fluid?

Answer 9

Fluid outside the cells, constituting about one-third of the body’s fluid, and is in constant motion. Electrolytes include sodium, chloride , bicarbonate

Question 10

What is the internal environment of the body also called?

Answer 10

Milieu intérieur.

Question 11

What is the primary role of extracellular fluid?

Answer 11

To provide ions and nutrients needed by the cells to maintain life.

Question 12

What distinguishes extracellular fluid from intracellular fluid?

Answer 12

Extracellular fluid contains sodium, chloride, and bicarbonate ions, while intracellular fluid contains potassium, magnesium, and phosphate ions.

Question 13

Who coined the term homeostasis?

Answer 13

Walter Cannon in 1929.

Question 14

What is homeostasis?

Answer 14

The maintenance of nearly constant conditions in the internal environment.

Question 15

What are examples of organs that help maintain homeostasis?

Answer 15

• Lungs (provide oxygen)
• Kidneys (maintain ion concentrations)
• Gastrointestinal system (provides nutrients, eliminates waste)

Question 16

How do homeostatic mechanisms operate in diseases?

Answer 16

They continue to operate and maintain vital functions through compensations, which may lead to deviations from normal ranges.

Question 17

What are the two stages of extracellular fluid transport?

Answer 17

• Movement of blood through the body in blood vessels
• Movement of fluid between blood capillaries and intercellular spaces

Question 18

What happens at the capillary walls?

Answer 18

Continual exchange of extracellular fluid occurs between the plasma portion of the blood and interstitial fluid.

Question 19

What is the role of the respiratory system in nutrient transport?

Answer 19

It allows blood to pick up oxygen in the alveoli.

Question 20

What substances does the liver modify?

Answer 20

Chemical compositions of substances absorbed from the gastrointestinal tract.

Question 21

What is the primary function of the kidneys?

Answer 21

To remove substances from plasma that are not needed by cells, including metabolic waste products.

Question 22

What does the musculoskeletal system provide for homeostasis?

Answer 22

Mobility for obtaining food and protection against adverse surroundings.

Question 23

How does the body eliminate carbon dioxide?

Answer 23

Through the lungs during respiration.

Question 24

What is the composition of the nervous system?

Answer 24

• Sensory input portion
• Central nervous system (integrative portion)
• Motor output portion

Question 25

What does the autonomic system control?

Answer 25

Functions of internal organs at a subconscious level.

Question 26

What are hormones?

Answer 26

Chemical substances secreted by endocrine glands that are transported in extracellular fluid to help regulate body functions.

Question 27

What is the function of the autonomic nervous system?

Answer 27

Controls subconscious functions of internal organs, including heart activity and gastrointestinal movements ## Footnote The autonomic system operates without conscious control.

Question 28

What are hormones?

Answer 28

Chemical substances secreted by endocrine glands to regulate cellular function ## Footnote Hormones are transported in extracellular fluid.

Question 29

How does thyroid hormone affect the body?

Answer 29

Increases rates of most chemical reactions in all cells ## Footnote Helps set the tempo of bodily activity.

Question 30

What is the role of insulin?

Answer 30

Controls glucose metabolism in the body ## Footnote Insulin is produced by the pancreas.

Question 31

What does the immune system protect the body against?

Answer 31

Pathogens such as bacteria, viruses, parasites, and fungi ## Footnote Includes white blood cells and lymphatic structures.

Question 32

What is the integumentary system?

Answer 32

The skin and its appendages that protect deeper tissues and organs ## Footnote Important for temperature regulation and sensory interface.

Question 33

How does reproduction contribute to homeostasis?

Answer 33

Generates new beings to replace dying ones, maintaining continuity of life ## Footnote Sometimes considered a non-homeostatic function.

Question 34

What are control systems in the body?

Answer 34

Systems that regulate functions of organs and maintain homeostasis ## Footnote Includes genetic and physiological control systems.

Question 35

How does the body regulate oxygen concentration?

Answer 35

Through the oxygen-buffering function of hemoglobin ## Footnote Hemoglobin releases oxygen based on tissue fluid concentration.

Question 36

What role do baroreceptors play in blood pressure regulation?

Answer 36

Detect stretch in arterial walls and send signals to the brain to adjust blood pressure ## Footnote They inhibit the vasomotor center when pressure is too high.

Question 37

What is negative feedback?

Answer 37

A control mechanism that counteracts changes to maintain homeostasis ## Footnote Most body control systems operate by negative feedback.

Question 38

What is the gain of a control system?

Answer 38

The effectiveness of a control system in maintaining constant conditions ## Footnote Calculated as the correction divided by the error.

Question 39

What is an example of positive feedback in the body?

Answer 39

Blood clotting process and childbirth contractions ## Footnote Positive feedback can lead to instability but is useful in specific situations.

Question 40

How does positive feedback contribute to nerve signal generation?

Answer 40

Causes a rapid influx of sodium ions, leading to action potential ## Footnote This process amplifies the initial stimulus.

Question 41

What is the normal pH value of extracellular fluid?

Answer 41

7.4 ## Footnote Lethal values are only about 0.5 on either side of normal.

Question 42

What can happen if potassium ion concentration decreases significantly?

Answer 42

Can lead to paralysis due to inability of nerves to carry signals ## Footnote Normal potassium levels are crucial for nerve function.

Question 43

What happens to the body when carbon dioxide concentration increases?

Answer 43

Stimulates rapid and deep breathing to expel excess carbon dioxide ## Footnote This helps to regulate extracellular fluid composition.

Question 44

What is the role of the liver and pancreas in the body?

Answer 44

Control glucose concentration in the extracellular fluid ## Footnote They play key roles in metabolic regulation.

Question 45

What is the significance of extracellular fluid constituents?

Answer 45

They have narrow normal ranges; deviations can cause serious health issues ## Footnote Examples include temperature, pH, and ion concentrations.

Question 46

What is a vicious cycle in positive feedback?

Answer 46

A situation where the initiating stimulus causes further worsening of a condition ## Footnote An example is severe blood loss leading to heart failure.

Question 47

What initiates additional action potentials in nerve fibers?

Answer 47

Electrical current flowing along the outside and inside of the fiber

Question 48

What type of feedback is part of an overall negative feedback process in blood clotting?

Answer 48

Positive feedback

Question 49

What mechanism does the brain use for rapid body movements?

Answer 49

Feed-forward control

Question 50

What is the purpose of adaptive control in the nervous system?

Answer 50

To correct feed-forward signals for future movements

Question 51

True or False: Physiological variables such as blood pressure and metabolic rate remain constant throughout the day.

Answer 51

False

Question 52

What average body weight is often used as a reference in physiological discussions?

Answer 52

70-kg young, lean male

Question 53

How has the average body weight of American males changed since the 1960s?

Answer 53

Increased from 70 kg to over 88 kg

Question 54

What are some factors that contribute to physiological variability among individuals?

Answer 54

* Body weight * Height * Diet * Age * Sex * Environment * Genetics

Question 55

What percentage of body weight is total body water in a lean young male?

Answer 55

About 60%

Question 56

What physiological changes occur as a person ages?

Answer 56

* Declining skeletal muscle mass * Increasing fat mass

Question 57

What is the main purpose of the body's organization discussed in this chapter?

Answer 57

To maintain homeostasis in the extracellular fluid

Question 58

What is the internal environment of the body referred to as?

Answer 58

Extracellular fluid

Question 59

What happens when one or more functional systems lose their ability to contribute to body function?

Answer 59

All cells of the body suffer

Question 60

What does extreme dysfunction in the body lead to?

Answer 60

Death

Question 61

Fill in the blank: The body's cells operate in harmony to maintain _______.

Answer 61

Homeostasis