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Digestive System  The digestive system is the collective name used to describe the alimentary canal, some accessory          organs and a variety of digestive processes.  • The complex of digestive processes gradually breaks down the foods eaten until they are in a form suitable for absorption.  • After absorption, nutrients are used to synthesise body constituents. They provide the raw materials for the manufacture of new cells, hormones and enzymes, and the energy needed for these and other processes and for the disposal of waste materials.   The activities in the digestive system can be grouped under five main headings.  • Ingestion = This is the process of taking food into the alimentary tract.  • Propulsion = This moves the contents along the alimentary tract.  • Digestion = This consists of:  ➢ mechanical  breakdown of food e.g. mastication (chewing)  ➢ chemical digestion of food by enzymes present ...

 RESPIRATORY SYSTEM Respiration Respiration can be defined as exchange of gases i.e. oxygen and carbon dioxide between the atmosphere and tissues.  ✦ Organs of respiratory system Nose Pharynx Larynx Trachea Brochi - 2 Bronchioles Alveoli Lungs - 2 Muscles of respiration : Intercoastal muscles and Diaphragm ✦ Mechanism of respiration :- The normal human has 12-15 breath per min. Each breath consists of inspiration, expiration and pause. 1) Inspiration : The simultaneous contraction of intercoastal muscles and diaphragm increases the capacity of thoracic cavity. This reduces the pressure in the lungs. To equalize the pressure the air from atmosphere enters the lungs. The process of inspiration is active as it needs energy for muscle contraction. The inspiration lasts for 2 sec. 2) Expiration : Relaxation of intercostal muscles and diaphragm results in decrease in the space in the lungs. As a result, the pressure inside the lungs increases as compared to atmospheric pressure. Th...

  Animal Tissue - Types, Structure The animal cells are grouped together to form animal tissues. These tissues vary in their structure, function, and origin. The animal tissues are divided into epithelial, connective, muscular and nervous tissues. ✦ Types of Animal Tissue :- Animal tissues are distinguished into four basic types namely, epithelial tissue connective tissue nervous tissue muscle tissue 1) Epithelial Tissue :- Epithelial tissues form the protective covering and inner lining of the body and organs. These tissues were the first to evolve during evolution and were first formed during embryonic development. They develop from the ectoderm, mesoderm and endoderm of the embryo. ◉  Characteristics of Epithelial Tissues = Following are the important characteristics of epithelial tissues: These can be single-layered or multi-layered. The tissues have the power to regenerate. These are held together by gap junctions, tight junctions, zonula adheren, desmosomes, or interdigi...

BLOOD Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood is composed of blood cells suspended in blood plasma. Plasma , which constitutes 55% of blood fluid, is mostly water (92% by volume) , and contains proteins, glucose, mineral ions, and hormones. The blood cells are mainly red blood cells (erythrocytes) , white blood cells (leukocytes) , and (in mammals) platelets (thrombocytes) . The most abundant cells are red blood cells . These contain hemoglobin, which facilitates oxygen transport by reversibly binding to it, increasing its solubility. Jawed vertebrates have an adaptive immune system, based largely on white blood cells. White blood cells help to resist infections and parasites. Platelets are important in the clotting of blood. Blood is circulated around the body through blood vessels by the pumpi...

 ENDOMEMBRANE SYSTEM                          The Endomembrane system is a membranous component of the eukaryotic cell. The cytoplasm of the cell contains a system of membranous organelles that are suspended in it. The organelles are termed as a system even though they have different structures and functions as they are essential to the working of the cell. All these organelles work in coordination and they include the cell membrane , vacuoles , the nuclear membrane , lysosomes , Golgi complex , vesicles and the endoplasmic reticulum (ER) .                          Since the functioning of other organelles like mitochondria, chloroplasts etc, are not coordinated with the functioning of the above, they are not considered part of the system.  ❉ Components of the Endomembrane System            ...