It is an area of the brain that produces hormones that control: Body temperature. The hunger. Moods.

The thymus is a primary and specialized lymphoid organ of the immune system. Within the thymus, T cells mature.

A small gland that produces steroid hormones, epinephrine and norepinephrine These hormones help control heartbeat, blood pressure and other important body functions.

The pancreas is a large gland located behind the stomach and near the first part of the small intestine that secretes digestive juices into the small intestine through a tube called the pancreatic duct.

- Bacteria are small organisms that can invade the body, causing illness. These infections usually trigger a protective immune response. You also have innate bacteria in your body that helps digest your food and protect your body from harmful bacteria.
- An infection occurs when another organism enters your body and causes disease. The organisms that cause infections are very diverse and can include things like viruses, bacteria, fungi, and parasites.

- Infectious diseases are disorders caused by organisms, such as bacteria, viruses, fungi, or parasites. Many organisms live inside and outside our bodies. They are usually harmless or even useful. But under certain conditions, some organisms can cause disease.

- Bacteria are prokaryotic microorganisms that are a few microns in size, usually between 0.5 and 5 µm in length and of various shapes, including cocci spheres, rods, curved and helical spiral filaments, and spirochetes.

Causes:

- Bacterial infections are caused by the transmission of bacteria. You can be exposed to bacteria from other people, through the environment, or from eating contaminated food or drinking contaminated water
- Bacteria must enter your body for them to cause an infection. So you can get a bacterial infection through an opening in your skin, such as a cut, a bug bite, or a surgical wound. Bacteria may also enter your body through your airway and cause infections like bacterial pneumonia.
- Many human infections are caused by either bacteria or viruses. Bacteria are tiny single-celled organisms, thought by some researchers to be related to plants. They are among the most successful life forms on the planet, and range in habitat from ice slopes to deserts.

The human respiratory system is a series of organs responsible for taking in oxygen and expelling carbon dioxide. The primary organs of the respiratory system are the lungs, which carry out this exchange of gases as we breathe.

The lungs: The lungs are a pair of spongy, air-filled organs located on either side of the chest (thorax). The trachea (windpipe) conducts inhaled air into the lungs through its tubular branches, called bronchi.

Alveoli: Alveoli are an important part of the respiratory system whose function it is to exchange oxygen and carbon dioxide molecules to and from the bloodstream.

Red blood cells: Red blood cells: The blood cells that carry oxygen. Red cells contain hemoglobin and it is the hemoglobin which permits them to transport oxygen (and carbon dioxide). Hemoglobin, aside from being a transport molecule, is a pigment. It gives the cells their red color (and their name).