GAMSAT Biology Crash Course #3 - Body Systems | Section 3 for NSBs

Recent questions

• What is the cardiovascular system?

  The cardiovascular system is a complex network that includes the heart and blood vessels, responsible for circulating blood throughout the body. The heart, which is central to this system, consists of four chambers: the right atrium, left atrium, right ventricle, and left ventricle. Blood flows through these chambers, regulated by valves such as the tricuspid and mitral valves, ensuring unidirectional flow. The right atrium receives deoxygenated blood from the body, while the left atrium receives oxygenated blood from the lungs. The left ventricle, with its thick muscular wall, pumps oxygenated blood into the aorta, distributing it to the rest of the body. This system operates in two phases: diastole, when the heart relaxes and fills with blood, and systole, when it contracts to pump blood out. Understanding the cardiovascular system is crucial for grasping how blood circulation supports overall health and function.

• How does the respiratory system work?

  The respiratory system is essential for gas exchange, allowing oxygen to enter the body and carbon dioxide to be expelled. It comprises the upper airways, including the mouth and nose, and the lower airways, which consist of the trachea and bronchi leading to the alveoli, where gas exchange occurs. The mechanics of breathing involve the diaphragm, a muscular structure that contracts and pulls downwards, creating negative pressure that draws air into the lungs. Intercostal muscles between the ribs assist in expanding and contracting the rib cage, further facilitating lung inflation. During inhalation, the ribs move outward and upward, increasing the volume of the thoracic cavity. The total surface area of the lungs, if flattened, is comparable to a tennis court, optimizing the efficiency of gas exchange. Spirometry can measure various lung volumes, helping assess respiratory health and function.

• What is the function of the kidneys?

  The kidneys play a vital role in maintaining homeostasis by filtering blood to produce urine, which removes waste and excess substances from the body. Each kidney contains nephrons, the functional units that filter blood through structures called glomeruli and Bowman’s capsules. The renal tubule processes the filtrate, reabsorbing essential nutrients like sodium, glucose, and potassium, while balancing electrolytes and hydration. The loop of Henle is particularly important for reabsorption, ensuring that the body retains necessary substances. The collecting duct further regulates water balance; if the body is dehydrated, more water is reabsorbed into the bloodstream, while excess water is excreted when hydration levels are adequate. This intricate process is crucial for regulating blood pressure, electrolyte levels, and overall fluid balance in the body.

• What are the main functions of the endocrine system?

  The endocrine system is a complex network of glands that produce and secrete hormones, which are signaling molecules that regulate various physiological processes in the body. Key components of this system include the hypothalamus, pituitary gland, adrenal glands, pancreas, thyroid, and reproductive glands (testes and ovaries). Hormones released by these glands influence metabolism, growth, mood, and reproductive functions, among other critical bodily functions. For instance, the hypothalamus secretes corticotropin-releasing hormone, which signals the anterior pituitary to release hormones that can stimulate the adrenal glands to produce cortisol, a hormone involved in stress response. The endocrine system operates through feedback mechanisms, ensuring that hormone levels remain balanced and responsive to the body's needs, thus playing a crucial role in maintaining homeostasis.

• What is the gastrointestinal system?

  The gastrointestinal (GI) system is a complex network responsible for the digestion and absorption of nutrients from food. It begins at the mouth, where mechanical and enzymatic processes start breaking down food, and continues through the esophagus, stomach, small intestine, large intestine, and rectum. In the stomach, food is mixed with gastric acid and enzymes, further aiding digestion. The small intestine is where most nutrient absorption occurs, with the help of bile produced by the liver, which emulsifies fats for better absorption. The large intestine primarily absorbs water and electrolytes, while gut bacteria assist in breaking down fiber. This continuous digestive tube ensures that nutrients are efficiently extracted and waste is eliminated, highlighting the GI system's essential role in overall health and nutrition.