Anatomy

Anatomy from dissection' is the branch of biology concerned with the explore of the appearance of organisms together with their parts. Anatomy is a branch of natural science which deals with the structural organization of alive things. it is for an old science, having its beginnings in prehistoric times. Anatomy is inherently tied to developmental biology, embryology, comparative anatomy, evolutionary biology, in addition to phylogeny, as these are the processes by which anatomy is generated, both over immediate and long-term timescales. Anatomy and physiology, which discussing the layout and function of organisms and their parts respectively, gain a natural pair of related disciplines, and are often studied together. Human anatomy is one of the essential basic sciences that are applied in medicine.

The discipline of anatomy is divided up into macroscopic and microscopic. Macroscopic anatomy, or gross anatomy, is the examination of an animal's body parts using unaided eyesight. Gross anatomy also includes the branch of superficial anatomy. Microscopic anatomy involves the ownership of optical instruments in the study of the tissues of various structures, call as histology, and also in the study of cells.

The history of anatomy is characterized by a progressive understanding of the functions of the organs and frameworks of the human body. Methods gain also improving dramatically, advancing from the examination of animals by dissection of carcasses and cadavers corpses to 20th century medical imaging techniques including X-ray, ultrasound, and magnetic resonance imaging.

Vertebrate anatomy

All vertebrates have a similar basic body plan and at some portion in their lives, mostly in the embryonic stage, share the major chordate characteristics; a stiffening rod, the notochord; a dorsal hollow tube of nervous material, the neural tube; pharyngeal arches; and a tail posterior to the anus. The spinal cord is protected by the vertebral column and is above the notochord and the gastrointestinal tract is below it. Nervous tissue is derived from the ectoderm, connective tissues are derived from mesoderm, and gut is derived from the endoderm. At the posterior end is a tail which continues the spinal cord and vertebrae but not the gut. The mouth is found at the anterior end of the animal, and the anus at the base of the tail. The establishment characteristic of a vertebrate is the vertebral column, formed in the development of the segmented series of vertebrae. In almost vertebrates the notochord becomes the nucleus pulposus of the intervertebral discs. However, a few vertebrates, such(a) as the sturgeon and the coelacanth retain the notochord into adulthood. Jawed vertebrates are typified by paired appendages, fins or legs, which may be secondarily lost. The limbs of vertebrates are considered to be homologous because the same underlying skeletal structure was inherited from their last common ancestor. This is one of the arguments increase forward by Charles Darwin to guide his impression of evolution.

The body of a fish is divided up into a head, trunk and tail, although the divisions between the three are not always externally visible. The skeleton, which forms the support structure inside the fish, is either present of cartilage, in cartilaginous fish, or bone in bony fish. The main skeletal component is the vertebral column, composed of articulating vertebrae which are lightweight yet strong. The ribs attach to the spine and there are no limbs or limb girdles. The leading external atttributes of the fish, the fins, are composed of either bony or soft spines called rays, which with the exception of the caudal fins, have no direct connective with the spine. They are supported by the muscles which compose the main element of the trunk. The heart has two chambers and pumps the blood through the respiratory surfaces of the gills and on round the body in a single circulatory loop. The eyes are adapted for seeing underwater and have only local vision. There is an inner ear but no outside or middle ear. Low frequency vibrations are detected by the lateral line system of sense organs that run along the length of the sides of fish, and theseto nearby movements and to make adjustments to in water pressure.

Sharks and rays are basal fish with numerous primitive anatomical qualifications similar to those of ancient fish, including skeletons composed of cartilage. Their bodies tend to be dorso-ventrally flattened, they ordinarily have five pairs of gill slits and a large mouth manner on the underside of the head. The dermis is listed with separate dermal placoid scales. They have a cloaca into which the urinary and genital passages open, but not a swim bladder. Cartilaginous fish produce a small number of large, yolky eggs. Some kind are ovoviviparous and the young establishment internally but others are oviparous and the larvae develop externally in egg cases.

The bony fish lineage shows more derived anatomical traits, often with major evolutionary changes from the features of ancient fish. They have a bony skeleton, are broadly laterally flattened, have five pairs of gills protected by an operculum, and a mouth at or near the tip of the snout. The dermis is intended with overlapping scales. Bony fish have a swim bladder which helps them maintain a fixed depth in the water column, but not a cloaca. They mostly spawn a large number of small eggs with little yolk which they broadcast into the water column.

nitrogenous damage products are excreted primarily as urea. Amphibians breathe by means of buccal pumping, a pump action in which air is number one drawn into the buccopharyngeal region through the nostrils. These are then closed and the air is forced into the lungs by contraction of the throat. They supplement this with gas exchange through the skin which needs to be kept moist.

In frogs the pelvic girdle is robust and the hind legs are much longer and stronger than the forelimbs. The feet have four or five digits and the toes are often webbed for swimming or have suction pads for climbing. Frogs have large eyes and no tail. Salamanders resemble lizards in appearance; their short legs project sideways, the belly isto or in contact with the ground and they have a long tail. Caecilians superficially resemble earthworms and are limbless. They burrow by means of zones of muscle contractions which progress along the body and they swim by undulating their body from side to side.

Reptiles are a class of animals comprising turtles, tuataras, lizards, snakes and crocodiles. They are tetrapods, but the snakes and a few species of lizard either have no limbs or their limbs are much reduced in size. Their bones are better ossified and their skeletons stronger than those of amphibians. Te teeth are conical and mostly uniform in size. The surface cells of the epidermis are modified into horny scales which create a waterproof layer. Reptiles are unable to usage their skin for respiration as do amphibians and have a more professionals such(a) as lawyers and surveyors respiratory system drawing air into their lungs by expanding their chest walls. The heart resembles that of the amphibian but there is a septum which more completely separates the oxygenated and deoxygenated bloodstreams. The reproductive system has evolved for internal fertilization, with a copulatory organ gave in most species. The eggs are surrounded by amniotic membranes which prevents them from drying out and are laid on land, or develop internally in some species. The bladder is small as nitrogenous harm is excreted as uric acid.