Question

_______ is a chemical messenger secreted by fat cells that acts as an appetite suppressant. a. orexin b. angiotensin c. leptin d. ghrelin

Short answer

c. leptin

Step-by-step solution

Understand Each Option

Each option in this exercise refers to a type of hormone. Orexin, also known as hypocretin, is a neuropeptide that regulates arousal, wakefulness, and appetite. Angiotensin is part of the renin–angiotensin system within the body that regulates blood pressure. Leptin is a hormone predominantly made by adipose cells and enterocytes in the small intestines that helps to regulate energy balance by inhibiting hunger. Ghrelin is a hormone produced by cells in the gastrointestinal tract that stimulates appetite.

Match the Function with Options

The exercise asks for a hormone secreted by fat cells that acts as an appetite suppressant. Among the options, leptin is a hormone secreted by fat cells and its key role is to inhibit hunger, thereby acting as an appetite suppressant.

Key concepts

Appetite Regulation

Appetite regulation is a complex process controlled by different hormones and signaling pathways. It helps maintain energy balance in the body by adjusting hunger and food intake. The main purpose is to ensure that the body has enough energy to perform daily activities and maintain healthy weight levels.

The brain plays a significant role in appetite regulation, particularly the hypothalamus. This part of the brain receives signals from hormones produced in the gut, pancreas, and adipose tissue (fat cells). These hormones inform the brain about the body's energy status.

Some hormones stimulate appetite, like ghrelin, which tells the brain when it's time to eat. Others, such as leptin, suppress appetite, signaling to the brain that enough energy has been stored. By balancing these signals, the body can maintain stable energy levels and a healthy balance between hunger and fullness.

• This process helps avoid overeating or undereating.
• It protects against excessive weight gain or malnutrition.

Leptin

Leptin is a key hormone involved in appetite regulation and energy balance. It is primarily produced by fat cells, also known as adipocytes. When fat stores increase, fat cells release more leptin into the bloodstream.

This hormone travels to the hypothalamus in the brain. Upon receiving the leptin signal, the brain reduces appetite and encourages the body to burn stored fat. This is why leptin is often referred to as an appetite suppressant.

However, leptin resistance can occur, especially in people with obesity. This means that while leptin levels are high, the brain doesn't respond to its signals effectively.

• This results in continued hunger even when energy stores are sufficient.
• It can lead to weight gain and obesity-related health issues.

Endocrine System

The endocrine system is a network of glands and organs that produce, store, and release hormones. These hormones regulate many bodily functions, including growth, metabolism, reproduction, and mood.

This system includes numerous glands, such as the pituitary, thyroid, adrenal, and pancreas. It also involves organs like the stomach and fat tissue that secrete hormones involved in appetite regulation.

Hormones in the endocrine system travel through the bloodstream to reach their target organs and tissues. They act as messengers, conveying information that prompts certain actions or responses from these organs.

Important hormones related to appetite regulation include:

• Leptin: Supresses appetite.
• Ghrelin: Stimulates hunger.
• Insulin: Regulates blood sugar levels, impacting how full or hungry a person feels.

By coordinating different signals, the endocrine system ensures that the body's energy needs are met efficiently.