Chapter 5 - Section 5.6 - Study Guide - Assess Your Learning Outcomes - Page 173: 6

**Tissue atrophy** refers to the process of shrinking or wasting away of a tissue or organ, resulting in a decrease in its size, mass, and functional capacity. It often occurs when there is a reduction in the number or size of cells and the extracellular matrix that make up the tissue. Atrophy can be a normal part of aging or development, but it can also be a pathological response to various factors. Two common forms or causes of atrophy are: **1. Disuse Atrophy:** - **Definition:** Disuse atrophy occurs when a tissue or muscle undergoes a reduction in size and function due to a lack of physical activity or use. - **Mechanism:** When a muscle or tissue is not regularly exercised or used, the body responds by reducing the number and size of muscle fibers or cells, as well as the supportive structures. - **Examples:** Muscle disuse atrophy can occur in individuals who are bedridden or have immobilized limbs due to injury or illness. It can also affect unused organs like the thymus gland, which tends to shrink with age when it's less active. **2. Age-Related Atrophy (Senile Atrophy):** - **Definition:** Age-related atrophy is a natural process in which tissues and organs gradually decrease in size and function as a person grows older. - **Mechanism:** It is often a result of the normal aging process, where there is a gradual decline in cell replication, tissue turnover, and the body's ability to repair and replace damaged cells. - **Examples:** Age-related atrophy can affect various tissues and organs. For instance, the brain may undergo atrophy with aging, leading to cognitive changes. Additionally, skeletal muscle mass tends to decrease in older individuals, a condition known as sarcopenia. It's important to note that while these are two common forms of atrophy, there are many other potential causes of tissue atrophy, including malnutrition, hormonal imbalances, nerve damage, chronic diseases, and certain medications. The specific cause and consequences of atrophy can vary depending on the affected tissue or organ and the underlying factors involved. Addressing the underlying cause, when possible, may help slow or reverse the atrophic process and preserve tissue function.

**Tissue atrophy** refers to the process of shrinking or wasting away of a tissue or organ, resulting in a decrease in its size, mass, and functional capacity. It often occurs when there is a reduction in the number or size of cells and the extracellular matrix that make up the tissue. Atrophy can be a normal part of aging or development, but it can also be a pathological response to various factors. Two common forms or causes of atrophy are: **1. Disuse Atrophy:** - **Definition:** Disuse atrophy occurs when a tissue or muscle undergoes a reduction in size and function due to a lack of physical activity or use. - **Mechanism:** When a muscle or tissue is not regularly exercised or used, the body responds by reducing the number and size of muscle fibers or cells, as well as the supportive structures. - **Examples:** Muscle disuse atrophy can occur in individuals who are bedridden or have immobilized limbs due to injury or illness. It can also affect unused organs like the thymus gland, which tends to shrink with age when it's less active. **2. Age-Related Atrophy (Senile Atrophy):** - **Definition:** Age-related atrophy is a natural process in which tissues and organs gradually decrease in size and function as a person grows older. - **Mechanism:** It is often a result of the normal aging process, where there is a gradual decline in cell replication, tissue turnover, and the body's ability to repair and replace damaged cells. - **Examples:** Age-related atrophy can affect various tissues and organs. For instance, the brain may undergo atrophy with aging, leading to cognitive changes. Additionally, skeletal muscle mass tends to decrease in older individuals, a condition known as sarcopenia. It's important to note that while these are two common forms of atrophy, there are many other potential causes of tissue atrophy, including malnutrition, hormonal imbalances, nerve damage, chronic diseases, and certain medications. The specific cause and consequences of atrophy can vary depending on the affected tissue or organ and the underlying factors involved. Addressing the underlying cause, when possible, may help slow or reverse the atrophic process and preserve tissue function.