Question

During the absorptive state, an animal is a. fasting. b. relying entirely on stored molecules for energy. c. absorbing nutrients from a recently ingested meal. d. metabolizing lipids stored in adipose tissue to supply ATP to its cells. e. doing both a and b

Short answer

The correct answer is option (c): During the absorptive state, an animal is absorbing nutrients from a recently ingested meal.

Step-by-step solution

Understanding the Absorptive State

The absorptive state of an organism refers to the time during and after eating when nutrients are being absorbed from the digestive tract. This is a period when the body is making the most of the food recently ingested.

Eliminate Incorrect Options

Option (a) - 'fasting' is not true because the body is not fasting but is instead absorbing nutrients from food. Option (b) - 'relying entirely on stored molecules for energy' also does not hold true since during the absorptive state, the body is using the nutrients directly acquired and not the stored ones. Option (d) - 'metabolizing lipids stored in adipose tissue to supply ATP to its cells' is incorrect too because the body is using nutrients from ingested food, not stored lipids. Option (e) - 'doing both a and b' is not valid because both statements (a and b) are incorrect in this context.

Choose the Correct Option

Option (c) - 'absorbing nutrients from a recently ingested meal' is the correct choice. This accurately describes what happens during the absorptive state.

Key concepts

Nutrient Absorption

Nutrient absorption is a critical phase of the digestive process wherein the body converts food into a form that can be utilized by cells for energy and growth. During digestion, enzymes and other substances break down food particles in the stomach and intestines into smaller components, such as amino acids, fatty acids, and simple sugars. These components then pass through the lining of the small intestine and enter the bloodstream.

Once inside the bloodstream, these nutrients can be transported to various organs and tissues where they are needed. For instance, glucose is taken up by cells and utilized for energy production, while amino acids are used for the synthesis of proteins. Accessible nutrition from our meals is pivotal for maintaining essential bodily functions and supporting an active metabolism.

Effective nutrient absorption relies on a healthy digestive system. Conditions affecting the digestive tract, such as celiac disease or Crohn's disease, can hinder the body's ability to absorb certain nutrients, leading to deficiencies and other health issues. It is, therefore, vital to ensure the digestive system is functioning optimally for the best nutritional outcomes.

Digestive Tract Function

The function of the digestive tract is to process food, extract and absorb nutrients, and expel waste. It begins with ingestion, where food enters the mouth and is mechanically broken down by chewing. Saliva is mixed with food to initiate the chemical process of digestion. This mixture then travels down the esophagus into the stomach.

In the stomach, digestive enzymes and stomach acid further break down food into a semi-liquid form called chyme. This chyme then moves into the small intestine, where the majority of nutrient absorption takes place. The inner walls of the small intestine are lined with villi and microvilli, which increase the surface area for absorption.

Following nutrient absorption, the remaining indigestible food matter passes through the large intestine. Here, water is reabsorbed and the waste product is formed into stool. Contractions in the muscles of the large intestine eventually lead to the expulsion of waste through the rectum. Throughout this process, it's important for the body to properly manage its resources, particularly during the absorptive state after eating when nutrient levels are at their highest.

Metabolic States

The body's metabolic state can be broadly categorized into two main phases: the absorptive state and the post-absorptive (fasting) state. During the absorptive state, the body digests food and absorbs nutrients, leading to an increase in blood glucose levels. Insulin secretion is stimulated, which helps cells take in glucose and store excess energy for future use.

On the other hand, the post-absorptive state occurs when there has been no food intake for several hours. Blood glucose levels begin to drop, prompting the secretion of glucagon. This hormone helps maintain blood glucose at a stable level by promoting the release of stored glucose from the liver and the breakdown of fat in adipose tissue.

Understanding these metabolic states is crucial for comprehending how the body manages energy. In the absorptive state, the body's priority is to store energy from the recently ingested food. For students, recognizing these states aids in grasping concepts like energy storage and release, and how bodily functions adapt to different periods of food consumption and fasting.