Abdominal cavity in the context of "Thoracic cavity"

The thoracic diaphragm, or simply the diaphragm (/ˈdaɪəfræm/; Ancient Greek: διάφραγμα, romanized: diáphragma, lit. 'partition'), is a sheet of internal skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavity. The diaphragm is the most important muscle of respiration, and separates the thoracic cavity, containing the heart and lungs, from the abdominal cavity: as the diaphragm contracts, the volume of the thoracic cavity increases, creating a negative pressure there, which draws air into the lungs. Its high oxygen consumption is noted by the many mitochondria and capillaries present; more than in any other skeletal muscle.

The term diaphragm in anatomy, created by Gerard of Cremona, can refer to other flat structures such as the urogenital diaphragm or pelvic diaphragm, but "the diaphragm" generally refers to the thoracic diaphragm. In humans, the diaphragm is slightly asymmetric—its right half is higher up (superior) to the left half, since the large liver rests beneath the right half of the diaphragm.

An abdomen (also belly or stomach in vertebrates, or metasoma in arthropods) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal cavity. In arthropods, it is the posterior tagma of the body; it follows the thorax or cephalothorax.

In humans, the abdomen stretches from the thorax at the thoracic diaphragm to the pelvis at the pelvic brim. The pelvic brim stretches from the lumbosacral joint (the intervertebral disc between L5 and S1) to the pubic symphysis and is the edge of the pelvic inlet. The space above this inlet and under the thoracic diaphragm is termed the abdominal cavity. The boundary of the abdominal cavity is the abdominal wall in the front and the peritoneal surface at the rear.

The large intestine, also known as the large bowel, is the last part of the gastrointestinal tract and of the digestive system in tetrapods. Water is absorbed here and the remaining waste material is stored in the rectum as feces before being removed by defecation. The colon (progressing from the ascending colon to the transverse, the descending and finally the sigmoid colon) is the longest portion of the large intestine, and the terms "large intestine" and "colon" are often used interchangeably, but most sources define the large intestine as the combination of the cecum, colon, rectum, and anal canal. Some other sources exclude the anal canal.

In humans, the large intestine begins in the right iliac region of the pelvis, just at or below the waist, where it is joined to the end of the small intestine at the cecum, via the ileocecal valve. It then continues as the colon ascending the abdomen, across the width of the abdominal cavity as the transverse colon, and then descending to the rectum and its endpoint at the anal canal. Overall, in humans, the large intestine is about 1.5 metres (5 ft) long, which is about one-fifth of the whole length of the human gastrointestinal tract.

The pancreas (plural pancreases, or pancreata) is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e., it has both an endocrine and a digestive exocrine function. Ninety-nine percent of the pancreas is exocrine and 1% is endocrine. As an endocrine gland, it functions mostly to regulate blood sugar levels, secreting the hormones insulin, glucagon, somatostatin and pancreatic polypeptide. As a part of the digestive system, it functions as an exocrine gland secreting pancreatic juice into the duodenum through the pancreatic duct. This juice contains bicarbonate, which neutralizes acid entering the duodenum from the stomach; and digestive enzymes, which break down carbohydrates, proteins and fats in food entering the duodenum from the stomach.

Inflammation of the pancreas is known as pancreatitis, with common causes including chronic alcohol use and gallstones. Because of its role in the regulation of blood sugar, the pancreas is also a key organ in diabetes. Pancreatic cancer can arise following chronic pancreatitis or due to other reasons, and carries a very poor prognosis, as it is often only identified after it has spread to other areas of the body.

The human female reproductive system is made up of the internal and external sex organs that function in the reproduction of new offspring. The reproductive system is immature at birth and develops at puberty to be able to release matured ova from the ovaries, facilitate their fertilization, and create a protective environment for the developing fetus during pregnancy. The female reproductive tract is made of several connected internal sex organs—the vagina, uterus, and fallopian tubes—and is prone to infections. The vagina allows for sexual intercourse and childbirth, and is connected to the uterus at the cervix. The uterus (or womb) accommodates the embryo by developing the uterine lining.

The uterus also produces secretions which help the transit of sperm to the fallopian tubes, where sperm fertilize the ova. During the menstrual cycle, the ovaries release an ovum, which transits through the fallopian tube into the uterus. If an egg cell meets with sperm on its way to the uterus, a single sperm cell can enter and merge with it, creating a zygote. If no fertilization occurs, menstruation is the process by which the uterine lining is shed as blood, mucus, and tissue.