Skull

The skull is part of the skeleton, houses and protect the brain and the major sense organs.Important features include the nasal passages, containing the turbinals, which are delicate scrolls of paper thin bone, the orbits or eye sockets, the teeth bearing maxilla, or upper jaw, and mandible, or lower jaw, the zygomatic, arches, or cheekbones, the auditory bulla (in mammals), housing the bones of the middle ear; the formen magnum, a large opening through which the brain connects with the spinal cord; and mainly minute passage for nerves and blood vessels.

The deep skull bones that develop from cartilage are known as endochondrial bones, the superficial bones, including those of the face, develop directly from connective tissue membrane and are called dermal bones, or membrane bones. Most human skull bones are united, often across a wavy sufure, by connective fibrous tissue; a few are united by cartilage. Primitive land vertebrates had more than 50 paired skull bones, only 26 of these bones persist in humans and other mammals. In adult humans the braincase has a capacity of about 1,400 cm³ (85 in³) of soft tissue.

Human Skeleton

The human skeletal system is composed of individual bones and cartilage that receive a supply of blood and are held together by fibrous connective tissue, ligamens, and tendons. The three main fuctions of the skeletal system are protection, motion, and support. The system protect the body by enclosing the vital organs, it permits locomotion by responding at certain joints to the contractile activities of skeletal muscles, and it supports the body by serving as a framework to which tendons and fascia are attached, enabling skeletal muscles as a depot for calcium, which is vital to proper functioning of cell membranes, and for phosporus, which is needed in intermediary metabolism. In addition, the skeletal system is important because bone produce blood cells.

A birth the human body has about 275 bones, but as the body develops many of these bones fuse together. In the adult human the skeleton consist of 206 name bearing bones and a variable number of largely unnamed sesamoid bones. Sesamoid bones develop in the capsules of certain joints or in tendons, which hold muscle to bone, where they provide special support or reduce friction. The best known sesamoids are the patella (kneecap) and pisiform (wrist bone).

Classification of Bones
Bones may be classified as long, short, flat, irregular, or sesamoid. The long bones of the limbs consist of a central shaft (diaphysis) between two ends (epiphyses) that form joints with one or more other bones. The short bones, in the wrists and ankles, have a spongy core within a shell of compact bone. The flat bones include the ribs and many skull bones. They consist of two plates of compact bone with a spongy layer between. All this remaining named bones are irregular bones, except the patella, pisiform, and some foot bones.

Kidney Structure

Kidney is a human organ  like kidney beans shaped. In humans, kidney size, which is a length of 10 to 12 cm, width 5-6 cm, and thick, 3-4 cm, weighing about 140 grams. In cross kidneys, visible parts are different. The sections are from outside into the cortex, medulla, and pelvis. In the renal cortex and medulla there are about 1 million nephrons. Nephron is the structural and functional unit of the smallest of the kidney. Nephron serves as a screening tool.

Nephron is shaped like a large worm-headed eagle with a body like the winding. At the head there is a fine mesh that can only be bypassed by certain substances. Blood cells and blood proteins can not pass through this filter because it was bigger. The composition of the nephron consists of the following sections.

1) Malpighian Body, which includes Bowman's capsule and glomerulus.
2) convoluted tubules including proximal tubules, Henle, and distal tubules.

Some tubular-shaped winding, and some straight. The first section of the tubular winding, called the proximal tubule. After that there is a loop of Henle. Tubule weaved again as the second bend of the distal tubule called then concatenated with the tubule reservoir across the cortex and medulla. Each nephron consists of malpighi body. In this malpighi there is a section called Bowman's capsule-shaped bowl and in it there is glomerus. In the glomerular capillaries have blood.

Hand and Foot

The Hand contains a total of 27 bones and is the most flexible part of the human skeleton. Like other higher primates, humans possess nails instead of claws and have a thumb that can be rotated to oppose the other digits, enabling them to manipulate objects delicately and precisely. Higher primates other than humans, however, also use hands for locomotion; the development of an upright posture and consequent use of the hands for manipulation alone probably took place concurrently with the increase in brain size in humans. Shown here are some of the major muscle and tendon systems for moving the bones of the thumb and other digits.

The human foot differs from the feet of other higher primates in that it is used solely for locomotion, so that the big toe is no longer opposable to the other digits as it is in the great apes. Instead the bones of the feet have evolved in a way that enables humans to stride, and toes other than the big toe begin to show signs of degeneration. The heel bone bears most of the weight of the body and helps to form the longitudinal arch of the foot, along with the transverse arch formed by the metatarsal bones. If the ligamens between the bones weaken, the result is flatfoot, in which all instead of only part of the sole rests on the ground.