A Science Final On The Human Body

Extra calories are stored in the body as fat. When we consume more calories than our body needs for energy, the excess calories are converted into fat and stored in adipose tissue throughout the body. This fat serves as a reserve energy source that can be used when the body needs additional fuel. The accumulation of excess fat can lead to weight gain and various health issues, such as obesity and cardiovascular diseases. Therefore, it is important to maintain a balanced diet and engage in regular physical activity to prevent excessive storage of calories as fat.

Peristalsis refers to the wave-like muscle contractions that occur in the digestive tract to move food along. This process is considered a mechanical digestion because it involves physical movements that break down food into smaller pieces, making it easier for enzymes to further break down the nutrients during chemical digestion.

The correct answer is involuntary. The heart beat is controlled by the autonomic nervous system, specifically the cardiac center in the brainstem. It functions automatically and does not require conscious effort or control.

CO2 is produced as a waste product during cellular respiration in the body's tissues. It diffuses from the tissue cells into the nearby capillaries, where it is transported in the bloodstream to the lungs. In the lungs, the CO2 is exchanged for oxygen through the process of respiration. The oxygen-rich blood from the capillaries then reaches the alveoli, where the exchange of gases occurs. In the alveoli, the CO2 diffuses from the blood in the capillaries into the air sacs, and is eventually exhaled out of the body. Therefore, the correct answer is "alveoli to capillary".

If someone has blood type AB, they can receive blood from all types: A, B, O, and AB. This is because blood type AB has both A and B antigens on the red blood cells, making it compatible with all blood types.

The villi are finger-like projections in the small intestine that increase the surface area for nutrient absorption. They contain specialized cells called enterocytes, which have microvilli on their surface that further increase the absorption area. These cells have transport proteins that allow them to absorb nutrients from the digested food. Once absorbed, the nutrients can then enter the bloodstream and be transported to different parts of the body for energy and other functions.

The medulla is a part of the brainstem that is responsible for controlling many involuntary functions of the body, including the muscles involved in breathing, heart rate, blood pressure, and digestion. It acts as a relay station between the brain and the spinal cord, sending signals to the appropriate muscles to carry out these automatic actions without conscious effort or control. Therefore, the medulla is the correct answer as it controls involuntary muscles.

When cartilage is worn down, it can lead to a condition called osteoarthritis. This occurs when the protective cartilage that cushions the joints wears away, causing the bones to rub against each other. This friction and lack of cushioning can result in chronic pain and inflammation, leading to soreness. Therefore, if cartilage is worn down, a person may experience constant discomfort and soreness in the affected joints.

A hinge joint is a type of joint that allows movement in only one plane, similar to the movement of the elbow. It allows for back and forth movement, like the opening and closing of a door. This type of joint is found in various parts of the body, such as the knee and the fingers. It is characterized by the presence of a cylindrical bone that fits into a concave bone, allowing for smooth and stable movement.

Emphysema is a lung disease characterized by damage to the air sacs in the lungs, also known as alveoli. This damage causes the air sacs to lose their elasticity and ability to hold oxygen efficiently. As a result, the air sacs hold less oxygen, leading to difficulty in breathing and decreased oxygen levels in the body.

Spongy bone is a type of bone that is light and strong. It is found at the end of long bones, such as the femur. Spongy bone is characterized by its porous and honeycomb-like structure, which gives it its lightweight properties. Despite being lightweight, spongy bone is still strong and provides support and protection to the bone.

Osteoclasts are cells that break down bone tissue through a process called bone resorption. They are responsible for removing old or damaged bone tissue and help in the remodeling and repair of bones. Osteoclasts play a crucial role in maintaining the balance between bone formation and bone breakdown. They are essential for bone growth, healing fractures, and reshaping bones during development. Therefore, osteoclasts are the correct answer for what breaks down bones.

Arteries have thick walls compared to veins, capillaries, and the heart. Arteries are blood vessels that carry oxygen-rich blood away from the heart to various parts of the body. Their thick walls are composed of three layers - the inner layer called the endothelium, the middle layer made of smooth muscle, and the outer layer made of connective tissue. The thick walls of arteries help them withstand the high pressure and force exerted by the pumping action of the heart, allowing them to efficiently transport blood throughout the body.

Neurotransmitters are chemicals that transmit signals or impulses across synapses, the junctions between nerve cells. They are released by the axon of one neuron and bind to receptors on the dendrites of another neuron, allowing the impulse to be passed on. Therefore, the correct answer is "neurotransmitter."