BIOLOGY MISC

- Concept and importance of excretion: All biological processes that occur in the bodies of all living organisms are carried out through chemical reactions that leave some waste products. The living organism must get rid of these waste products as soon as they are formed, otherwise it will cause many problems and infections. - Excretion: the process by which the living organisms get rid of these waste products. Excretion in Animals Excretion refers to the materials that leave the body thr...

Mammalian Circulation Let’s first examine the overall organization of the mammalian cardiovascular system, beginning with the pulmonary circuit. 1. Contraction of the right ventricle pumps blood to the lungs via the 2. pulmonary arteries. As the blood flows through 3. capillary beds in the left and right lungs, it loads O2 and unloads CO2. Oxygen-rich blood returns from the lungs via the pulmonary veins to the 4. left atrium of the heart. Next, the oxygen-rich blood flows into ...

In mammals, a system of branching ducts conveys air to the lungs, which are located in the thoracic cavity. • Air enters through the nostrils and is then filtered by hairs, warmed, humidified, and sampled for odors as it flows through a maze of spaces in the nasal cavity. • The nasal cavity leads to the pharynx, an intersection where the paths for air and food cross. When food is swallowed, the larynx (the upper part of the respiratory tract) moves upward and tips the epiglottis over ...

5. The lymph nodes - The lymph nodes present along network of the lymphatic vessels that located in all the body parts under the armpits, at the two sides of the neck ,in upper thigh, and near the internal body’s organs. Their size ranging from a pinhead, to the seed of small beans. The node is divided internally into pockets filled with B- lymphocytes, T- lymphocytes, and macrophages and some other types of white blood cells that get rid of germs and the debris cells. • They purify ...