Test: Respiratory and Circulatory Systems - 2 - Class 4 MCQ

Veins are the type of blood vessels that carry carbon dioxide-rich blood back to the heart. They are thinner-walled than arteries and are designed to transport deoxygenated blood, which is collected from the body's tissues and returned to the heart for reoxygenation in the lungs.

The average resting heart rate for a healthy adult typically ranges from 60 to 100 beats per minute. This rate can vary based on factors such as age, fitness level, and overall health. Athletes, for instance, often have lower resting heart rates due to their higher cardiovascular efficiency.

The nose is responsible for filtering and warming the air before it enters the lungs. It contains mucous membranes and tiny hairs (cilia) that trap dust, pollen, and other particles, while also humidifying the air. This process helps protect the lungs from irritants and ensures that the air is at a suitable temperature and moisture level for respiration.

The main purpose of the circulatory system is to transport essential materials, such as oxygen, nutrients, hormones, and waste products, throughout the body. This transportation is vital for maintaining homeostasis, supporting cellular activities, and ensuring that all body systems function effectively.

Nutrients are transported to body cells through blood circulation. After digestion, nutrients are absorbed into the bloodstream from the intestines and then delivered to the cells via the circulatory system. This efficient transportation is crucial for providing cells with the energy and materials they need for growth and repair.

During inhalation, the chest cavity expands. This expansion occurs as the diaphragm contracts and moves downward, and the intercostal muscles between the ribs lift the rib cage. This increases the volume of the thoracic cavity, allowing air to be drawn into the lungs.

A unique feature of capillaries is that they allow for the exchange of substances between the blood and surrounding tissues. Their thin walls facilitate the diffusion of oxygen, nutrients, carbon dioxide, and waste products, making them essential for cellular metabolism and health.

The rib cage protects the heart. This bony structure surrounds the heart and lungs, providing a protective barrier against physical impacts and injuries. It also plays a crucial role in the mechanics of breathing by allowing the chest to expand and contract during inhalation and exhalation.

The bronchi function to connect the trachea (windpipe) to the lungs. They branch off into smaller bronchioles within the lungs, allowing air to travel deeper into the respiratory system for gas exchange. The bronchi also help to direct airflow and filter out larger particles from the air.

Capillaries are involved in nutrient absorption from the digestive system. After nutrients are absorbed in the intestines, they enter the capillaries, where they are transported into the bloodstream and delivered to cells throughout the body. The thin walls of capillaries enable efficient nutrient exchange, which is essential for maintaining health and energy levels.