The abdomen in a human and an ant.

In vertebrates such as mammals the abdomen (belly) constitutes the part of the body between the thorax (chest) and pelvis. Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands The thorax is a division of an Animal 's body that lies between the head and the Abdomen. The pelvis (pl pelvises or pelves) or pelvic girdle is the irregular bony structure located at the base of the spine (properly known The region enclosed by the abdomen is termed the abdominal cavity. The abdominal cavity is the Body cavity of the human body (and animal bodies that holds the bulk of the viscera and which is located below (or inferior In arthropods it is the most distal section of the body which lies behind the thorax or cephalothorax^[1][2]. Arthropods are Animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, " Joint " The cephalothorax (call prosoma in some groups is an anatomical term used in Arachnids and Malacostracan Crustaceans for the

Vertebrates

In vertebrates the abdomen is a large cavity enclosed by the abdominal muscles ventraly and lateraly and by vertebral column dorsally. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species In Human anatomy, the vertebral column ( backbone or spine) is a column of 34 Vertebrae the Sacrum, Intervertebral Lower ribs can also enclose ventral and lateral walls. Abdominal cavity is continuous with pelvic cavity. It is separated from thoracic cavity by diaphragm. The thoracic cavity (or chest cavity) is the chamber of the human body (and other animal bodies that is protected by the Thoracic wall ( Thoracic cage Structures such as the aorta, inferior vena cava and esophagus pass through the diaphragm. The superior and inferior vena cava are collectively called the venae cavae. The esophagus or oesophagus (see American and British English spelling differences) sometimes known as the gullet, is an organ in Both abdominal cavity and pelvic cavity are lined by a serous membrane known as parietal peritoneum. In higher Vertebrates the peritoneum is the Serous membrane that forms the lining of the abdominal cavity &mdash it covers most of the intra-abdominal This membrane is continuous with visceral peritoneum lining the organs^[3]. In higher Vertebrates the peritoneum is the Serous membrane that forms the lining of the abdominal cavity &mdash it covers most of the intra-abdominal Abdomen in vertebrates contains a number of organs belonging for instance to digestive tract and urinary system. In Biology, an organ ( Latin: organum, "instrument tool" from Greek όργανον - organon "organ instrument The urinary system (also called Excretory system or the genitourinary system (GUS is the Organ system that produces stores and eliminates Urine.

Abdominal organs

• Digestive tract: Stomach, small intestine, large intestine with cecum and appendix
• Accessory organs of the digestive tract: Liver, gallbladder and pancreas
• Urinary system: Kidneys and ureters
• Other organs: Spleen

Abdominal organs can be highly specialized in some animals. In Human anatomy, the stomach is a J-shaped hollow muscular organ of the Gastrointestinal tract involved in the second phase of Digestion, following In Biology the small Intestine is the part of the Gastrointestinal tract (gut between the Stomach and the Large intestine, and comprises The large intestine is the last part of the Digestive system: the final stage of the Alimentary canal in Vertebrate Animals Its function is to The cecum or caecum (from the Latin caecus meaning Blind) is a pouch connected to the Ascending colon of the Large In Human anatomy, the appendix (or vermiform appendix; also cecal (or caecal appendix; also vermix) is a blind ended tube connected to the The liver is a vital organ in the human body and is present in Vertebrates and some other animals The gallbladder (or cholecyst sometimes gall bladder is a small organ whose function in the body is to store Bile and aid in the digestive process The pancreas is a Gland organ in the digestive and Endocrine system of Vertebrates. The kidneys are complicated organs that have numerous biological roles In human Anatomy, the ureters are muscular ducts that propel Urine from the Kidneys to the Urinary bladder. The spleen is an organ found in all Vertebrate animals In humans the spleen is located in the abdomen of the body where it functions in the destruction of redundant Red For example the stomach of ruminants (a suborder of mammals) is divided into four chambers - rumen, reticulum, omasum and abomasum. Physiologically a ruminant is a Mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first stomach known This article is about the taxonomic rank for the sequence of species in a taxonomic list see Taxonomic order In scientific classification used The rumen, also known as a paunch, forms the larger part of the Reticulorumen, which is the first chamber in the Alimentary canal of Ruminant Reticulum (rɨˈtɪkjələm Reticle) is one of the minor southern Constellations It was introduced in the early 17th century by the astronomer Isaac Habrecht The omasum, also known as the bible, the fardel The abomasum, also known as the maw, and the rennet-bag ^[4]

Invertebrates

In the worker ant, the abdomen consists of the propodeum fused to the thorax and the metasoma, itself divided into the narrow petiole and bulbous gaster. The propodeum is the first abdominal segment in Apocrita Hymenoptera ( Wasps Bees and Ants. The thorax is a division of an Animal 's body that lies between the head and the Abdomen. The metasoma is the posterior part of the body or tagma, of Arthropods whose body is composed of three parts the other two being the Prosoma and the In Entomology, the term petiole is most commonly used to refer to the constricted first (and sometimes second Metasomal segment of members of the Hymenopteran The gaster is the bulbous posterior portion of the Metasoma found in Apocrita Hymenoptera ( Bees Wasps and Ants.

The invertebrate abdomen is built up of a series of concave upper plates known as tergites and convex lower plates known as sternites, the whole being held together by a tough yet stretchable membrane. A tergum (plural terga, associated adjective tergal) is the dorsal portion of an Arthropod segment other than the head The sternum (pl "sterna" is the Ventral portion of a segment of an Arthropod Thorax or Abdomen.

The abdomen contains the insect's digestive tract and reproductive organs, it consists of eleven segments in most orders of insects though the eleventh segment is absent in the adult of most higher orders. The number of these segments does vary from species to species with the number of segments visible reduced to only seven in the common honeybee. This article refers collectively to all true honey bees for the "common" domesticated honey bee see European honey bee Honey bees In the Collembola (Springtails) the abdomen has only six segments. Springtails ( Collembola) form the largest of the three lineages of modern hexapods that are no longer considered Insects (the other two are the

The abdomen is sometimes highly modified. In ants, the first segment of the abdomen is fused to the thorax and called the propodeum. Ants are social Insects of the family Formicidae and along with the related families of Wasps and Bees belong to the order The thorax is a division of an Animal 's body that lies between the head and the Abdomen. The propodeum is the first abdominal segment in Apocrita Hymenoptera ( Wasps Bees and Ants. The second segment forms the narrow petiole. In Entomology, the term petiole is most commonly used to refer to the constricted first (and sometimes second Metasomal segment of members of the Hymenopteran Some ants have an additional postpetiole segment, and the remaining segments form the bulbous gaster. The gaster is the bulbous posterior portion of the Metasoma found in Apocrita Hymenoptera ( Bees Wasps and Ants. [1] The petiole and gaster (abdominal segments 2 and onward) are collectively called the metasoma. The metasoma is the posterior part of the body or tagma, of Arthropods whose body is composed of three parts the other two being the Prosoma and the

Unlike other Arthropods, insects possess no legs on the abdomen in adult form, though the Protura do have rudimentary leg-like appendages on the first three abdominal segments, and Archaeognatha possess small, articulated "styli" which are sometimes considered to be rudimentary appendages. The Protura, or proturans, and sometimes nicknamed coneheads are an order of hexapods previously regarded as insects and sometimes treated as Archaeognatha is an order of wingless Insects also known as jumping bristletails. Many larval insects including the Lepidoptera and the Symphyta (Sawflies) have fleshy appendages called prolegs on their abdominal segments (as well as their more familiar thoracic legs), which allow them to grip onto the edges of plant leaves as they walk around. Lepidoptera is an order of Insect that includes Moths and butterflies. Symphyta redirects here For the Moth Genus, see Symphyta (genus. Prolegs are the fleshy stubby little structures found on the ventral surface of the Abdomen of most larval forms of Insects of the Order Lepidoptera

See also

• Human abdomen
• Opisthosoma
• Metasoma

References

1. ^ Abdomen. The human abdomen (from the Latin word meaning "belly" is the part of the body between the Pelvis and the thorax. The opisthosoma is the posterior portion of the Arachnids body behind the Prosoma (cephalothorax The metasoma is the posterior part of the body or tagma, of Arthropods whose body is composed of three parts the other two being the Prosoma and the (n. d. ). Dictionary. com Unabridged (v 1. 1). URL: http://dictionary.reference.com/browse/abdomen [Accessed: 22 Oct 2007]
2. ^ Abdomen. Dictionary. com. The American Heritage Dictionary of the English Language, 4th Edition. URL: http://dictionary.reference.com/browse/abdomen [Accessed: 22 October 2007].
3. ^ Peritoneum. The Veterinary Dictionary. Elsevier, 2007. http://www.answers.com/topic/peritoneum [Accessed: 22 Oct 2007)
4. ^ "Ruminant. " The Veterinary Dictionary. Elsevier, 2007. http://www.answers.com/topic/ruminant [Accessed: 22 Oct 2007].