T-helper cells, also known as CD4+ cells, are a type of white blood cell that play a crucial role in the immune system by coordinating the immune response. They help activate and direct other immune cells, such as B cells and T-killer cells, to fight off infections. T-killer cells, also known as cytotoxic T cells, are another type of white blood cell that are responsible for directly killing infected cells or cancer cells in the body. Together, T-helper cells and T-killer cells work in harmony to mount an effective immune response against pathogens. **

No, T-killer cells do not arise from T-lymphocytes due to the activation of T-helper cells. T-killer cells, also known as cytotoxic T cells, are a subset of T-lymphocytes that are activated by the recognition of specific antigens presented by antigen-presenting cells. Once activated, T-killer cells can directly kill infected or abnormal cells. T-helper cells, on the other hand, play a different role in the immune response by helping to activate other immune cells, including T-killer cells, through the release of cytokines. **

When T-helper cells are no longer present, the immune system's ability to coordinate an effective response to pathogens is compromised. This can lead to a weakened immune response, making the body more susceptible to infections and diseases. Without T-helper cells, other immune cells may not be properly activated, resulting in an inability to mount an appropriate immune response. This can have serious consequences for overall health and can lead to increased vulnerability to various illnesses. **

The HIV virus enters T-helper cells by binding to the CD4 receptor on the cell surface. Once inside the cell, the virus replicates and produces new viral particles, which can then infect other T-helper cells. This continuous cycle of infection and replication leads to a decline in the number of T-helper cells, weakening the immune system and making the body more susceptible to infections and diseases. Additionally, HIV can also directly cause cell death in T-helper cells, further contributing to the damage to the immune system. **

White blood cells, also known as leukocytes, are a crucial part of the immune system that help the body fight off infections and diseases. They are produced in the bone marrow and circulate throughout the body in the blood. White blood cells come in different types, each with specific functions such as engulfing bacteria, producing antibodies, or attacking viruses. Their main role is to identify and destroy pathogens to keep the body healthy. **

Sensory cells are specialized cells that detect and respond to specific stimuli, such as light, sound, touch, taste, and smell. These cells are found in sensory organs, which are structures in the body that contain sensory cells and are responsible for detecting and transmitting sensory information to the brain. The senses, on the other hand, are the physiological capacities of organisms that provide data for perception. They include sight, hearing, touch, taste, and smell, and are essential for experiencing and interacting with the environment. **

Yes, blood cells can burst in water. This is because blood cells contain a higher concentration of solutes (such as salts and proteins) than water. When blood cells are placed in a hypotonic solution like water, water molecules move into the cells in an attempt to equalize the concentration of solutes inside and outside the cells. This influx of water can cause the cells to swell and eventually burst. **

Nerve cells, also known as neurons, are the basic building blocks of the nervous system. They are specialized cells that transmit information through electrical and chemical signals. Sensory organs are specialized structures in the body that detect and respond to external stimuli, such as light, sound, touch, taste, and smell. These organs include the eyes, ears, skin, tongue, and nose, and they play a crucial role in allowing organisms to perceive and interact with their environment. **