Mammals

Mammals are the most developed class in the animal kingdom. They are over 200 million yeas old and lived even at the age of the dinosaurs. As their name reveals they feed their young with mammary glands. They give birth to live young and have hair compared to feathers or scales which other animal classes have.

Anatomy: From the anatomical point of view, their skeleton is in many ways similar to the human body. Their body is covered with a fur. They have got a bony skeleton. The spine can be divided into cervical, thoracic, lumbar, sacral and a tail part. The cervical consists of 7 parts / vertebrae (just like the humans), thoracic of 12-18 vertebrae and lumbar of 2-8 vertebrae. Sacral vertebrae are together fixed in the sacral bone. The number of vertebrae in the tail part may vary a lot. The first two vertebrae (atlas and axis) enable mammals to move their head to the sides (left / right) as well as up and down. Ribs are fixed to the thoracic vertebrae. They are also used as a great protection.

Physiology: Lungs consist of many small alveoli - this rapidly increases their inner surface. Diaphragm is between the thorax and the abdominal part. It also participates in breathing and is an inevitable inhaling muscle. The heart is made of four completely separated parts. There are two atriums and two ventricles. Deoxygenated blood flows through the right heart whereas the oxygenated blood flows through the left heart. So there are two separated blood circulations. The blood circulation starts in the right atrium and then the blood flows into the right ventricle. From the right ventricle the blood flows into the lungs where it is oxygenated. Consequently it flows into the left atrium and then into the left ventricle. From the left ventricle the oxygenated blood flows into the entire body to all organs. There it gives inevitable oxygen to tissues and last but not least the deoxygenated blood comes through veins into the right atrium. And in the right atrium it starts all over again. Mammals have got a constant body temperature, they are endothermic. They also do have sweat glands which enable them to cool themselves.
The alimentary canal starts with a mouth with teeth. Teeth have got different shape and different functions too. A food comes through the pharynx and esophagus into the stomach (gaster). Chemical digestion starts in stomach and is finished in duodenum, jejunum and ileum. Pancreas and gall bladder participate in digestion. Gall helps to digest fat and pancreatic enzymes proteins and sugars. Intestunum tenue (duodenum, jejunum and ileum) participates (apart from digestion) in resorption too. The concentration of indigestible food takes place in colon. Only water is digested there. The alimentary canal ends as an anus.
Mammals have got pair of kidneys, which excrete toxic and abundant fluid. They are placed in the lumbar area on the both sides. Nervous system is extraordinary developed. The frontal part has got the most impact over other brain parts. Sensory organs are well developed as well.