Physiology Chapter 1

Questions and Answers

What is the thickness range of the alveolar membrane through which oxygen diffuses?

2.1 to 5 micrometers

0.4 to 2.0 micrometers (correct)

1 to 2.5 micrometers

0.1 to 0.3 micrometers

Which of the following nutrients is NOT mentioned as being absorbed from ingested food into the extracellular fluid of the blood?

Amino acids

Vitamins (correct)

Carbohydrates

Fatty acids

What primarily influences the rate at which blood passes through the capillaries?

The thickness of the capillary walls

The viscosity of the blood

The rate of oxygen consumption

The level of physical activity of a person (correct)

What process occurs as blood moves through blood capillaries regarding the extracellular fluid?

Exchange between plasma and interstitial fluid Signup and view all the answers

In which organ system does significant nutrient absorption from blood occur in the context provided?

Gastrointestinal Tract Signup and view all the answers

What is a primary function of the alveolar membrane?

Allowing rapid diffusion of oxygen into blood Signup and view all the answers

During which condition does the heart pump blood through the gastrointestinal tract the most frequently?

When extremely active Signup and view all the answers

What component fills the intercellular spaces through which the extracellular fluid exchanges?

Interstitial fluid Signup and view all the answers

What factor is NOT mentioned as influencing variability among individuals regarding physiological functions?

Color of clothing Signup and view all the answers

What has been the trend in average body weight for males in recent years according to the provided content?

It has increased to over 88 kg Signup and view all the answers

Which aspect of physiological functions does the content state might not follow the average values for assessment?

Reproductive functions Signup and view all the answers

According to the content, for which group does the average physiological function typically not use the “average” standard?

Young, lean females Signup and view all the answers

How have physiological norms been assessed in the last few decades, according to the content?

By observing variations in an increasingly heavier population Signup and view all the answers

What is the primary reason plasma proteins do not pass through capillaries easily?

They are too large. Signup and view all the answers

Which organ is primarily responsible for altering the chemical composition of absorbed substances?

Liver Signup and view all the answers

What role do fat cells, gastrointestinal mucosa, kidneys, and endocrine glands serve in relation to absorbed substances?

They store or modify them until needed. Signup and view all the answers

How does diffusion occur between blood and tissue spaces?

Due to kinetic motion of molecules. Signup and view all the answers

What is one function of the liver regarding waste products?

It eliminates certain toxic substances. Signup and view all the answers

In what way does the musculoskeletal system contribute to homeostasis?

By performing movements in response to sensations. Signup and view all the answers

What signals are transmitted through the motor output portion of the nervous system?

Appropriate signals to carry out desires. Signup and view all the answers

What characterizes the process that allows fluid and its constituents to move across capillary walls?

Simple diffusion. Signup and view all the answers

Which of the following substances are likely absorbed in their original form by cells?

Simple sugars. Signup and view all the answers

What primarily drives the diffusion process between the blood and tissue spaces?

Concentration differences. Signup and view all the answers

What triggers the process of more blood clotting when a blood vessel is ruptured?

Activation of clotting factors within the clot Signup and view all the answers

What is the primary outcome when the positive feedback mechanism is excessive during blood loss?

Initiation of acute heart attacks Signup and view all the answers

How does blood pressure disturbance affect the baroreceptor control system?

It has a minimal effect by one-third Signup and view all the answers

What condition can lead to unwanted clot formation within the arteries?

Presence of atherosclerotic plaque Signup and view all the answers

When does bleeding cease as a result of clotting?

When a temporary plug is formed at the rupture site Signup and view all the answers

What initiates the clotting cascade once a blood vessel is damaged?

The rupture of the blood vessel Signup and view all the answers

What is a significant risk when blood loss reaches 2 liters or more?

Death from positive feedback mechanisms Signup and view all the answers

Which physiological control system has lesser gains compared to some others?

Baroreceptor system Signup and view all the answers

What can excessive activation of clotting factors lead to?

Formation of unwanted blood clots Signup and view all the answers

In what scenario is the body's feedback control system most effective?

During normal physiological conditions Signup and view all the answers

What mechanism does the brain use to cause required muscle contractions during high-speed movements?

Feed-forward control Signup and view all the answers

What physiological changes are typically associated with aging?

Decreased skeletal muscle mass and increased fat mass Signup and view all the answers

What is the process called that involves correcting feed-forward signals for muscle contractions based on sensory feedback?

Adaptive control Signup and view all the answers

Which of the following best describes the nature of adaptive control in motor functions?

Delayed negative feedback Signup and view all the answers

Which factor contributes to complexity in physiological variability?

Sex differences Signup and view all the answers

What consequence can occur when nerve signals take too long to reach the brain during rapid movements?

Impaired motor control Signup and view all the answers

What type of feedback does the brain utilize to enhance muscle contractions for subsequent movements?

Adaptive feedback Signup and view all the answers

What is the primary focus of the body’s complex feedback control systems, as discussed?

Movement accuracy Signup and view all the answers

What characterizes the decline in physiological control systems due to aging?

Decreased responsiveness to signals Signup and view all the answers

How does the brain determine if a movement is performed correctly during adaptive control?

By assessing sensory nerve signals Signup and view all the answers

Study Notes

Alveolar Membrane and Gas Exchange

The alveolar membrane thickness ranges from 0.4 to 2.0 micrometers, facilitating rapid oxygen diffusion into the blood.
Oxygen moves through this thin membrane into the blood via molecular motion due to kinetic energy.

Blood Circulation and Nutrient Absorption

The heart pumps blood into the gastrointestinal tract once per minute at rest and up to six times during extreme activity.
Nutrients such as carbohydrates, fatty acids, and amino acids are absorbed from the gastrointestinal tract into extracellular fluid.

Capillary Functionality

Blood capillary walls allow permeability to most plasma molecules, except for large plasma proteins.
Continuous exchange of extracellular fluid occurs between blood plasma and interstitial fluid, facilitating nutrient distribution and waste elimination.

Liver and Metabolism

The liver modifies absorbed substances into usable forms, while fat cells, kidneys, and other tissues assist in storage and processing.
The liver also detoxifies and eliminates waste products and toxic substances from the body.

Musculoskeletal System and Homeostasis

Muscles are crucial for maintaining homeostasis by facilitating movement in response to sensory input.
Feed-forward control allows the brain to initiate muscle contractions before sensory feedback confirms the action, enhancing movement efficiency.

Clotting Mechanism

Blood clotting involves activation of enzymes called clotting factors in response to vessel damage.
This positive feedback mechanism propagates until bleeding stops, although it can lead to unwanted clots and acute heart attacks.

Physiological Control Systems

Physiological responses vary in efficiency with age, leading to decreased muscle mass and organ function over time.
Complex factors influencing physiology include sex, age, diet, environment, and genetics, complicating the understanding of normal ranges.

Feedback Mechanisms

Adaptive control acts as a delayed negative feedback where the brain corrects movements based on prior performance.
Body control systems adjust continuously in reaction to disturbances, with extreme dysfunction being life-threatening and moderate dysfunction causing illness.

Body Composition Trends

The average body weight of American males has risen to over 88 kg and females to over 76 kg, exceeding historical averages significantly.
This trend reflects broader increases in body weight across industrialized nations over the past 40 to 50 years.

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Test your knowledge of the respiratory system, focusing on the alveolar membrane. This quiz covers the structure and function of alveoli and their interaction with pulmonary capillaries. Perfect for biology students looking to deepen their understanding of respiratory mechanisms.