Introduction to Lymphatic System

Components of Lymphatic System

Functions of Lymphatic System

1. REMOVE PARTICULATE MATTER: Lymph capillaries absorb and remove large protein molecules and other particulate matter from tissue spaces. In this way cellular debris and other harmful particles are washed away.
2. FILTER THE LYMPH FOR FOREIGN HARMFUL PARTICLES: Lymph nodes act as filter for the lymph and in this way they purify the lymph flowing through them.
3. PHAGOCYTOSIS: Antigens are removed from lymph by phagocytic activity of cells of lymph node.
4. PRODUCTION OF LYMPHOCYTES: Mature B-lymphocytes and mature T-lymphocytes are produced in lymph nodes.
5. IMMUNE RESPONSES: Lymphatic system can induce both cellular and humoral immune responses.

Introduction to Cardiovascular System

Cardiovascular system means the system of heart and blood vessels of human body. The term “cardiovascular” is a combination of two word; “Cardio” and “vascular”. The term “cardio” is derived from “cardiac” meaning Heart and the term “vascular” means blood vessels. So the name itself indicates that cardiovascular systems is the system of heart and blood vessels. Cardiovascular system is also known as “Circulatory System”.

Cardiovascular System

Components of Cardiovascular System 

Cardiovascular system is made up of three major components; Heart, Blood vessels and blood.
HEART:Heart is a hollow muscular organ made of strong cardiac muscles. Heart can push the blood through the circulatory system with great force. In fact push of the heart is the major force that causes circulation of blood throughout human body. Heart is made up of three layers; Pericardium, Myocardium and Endocardium. 

Human Heart

BLOOD VESSELS:Human beings have a closed type of circulatory system (visit my blog post: Difference between open and closed circulatory systems) in which blood does not come in direct contact with body tissues. Instead the blood flows in restricted pathways called blood vessels. Materials are exchanged between blood and body tissues through the walls of blood vessels. Thus blood vessels are pathways of blood flow in human body. There are three main types of blood vessels; Arteries, Capillaries and Veins.

BLOOD: Blood is a specialized tissue of body that exists in fluid form. It is one of the five basic types of tissues of human body. (Blog post:Basic tissue types of Human Body). Blood consists of two major portions: Blood cells and Plasma. Plasma is the watery portion of blood that makes it a fluid. 90% of blood plasma is water and remaining 10% are proteins, inclusions and waste products etc. Blood cells are of three main types: Red Blood Cells (RBCs), White Blood Cells (WBCs) and Platelets.

Bleeding Finger 

(SOURCE: "Flickr:Bleed/Wikipedia")

Importance of Cardiovascular System

Perfectly functioning Cardiovascular system is so important for human body, that if it stops for a minute, rapid death will occur. The flow of blood is necessary for existence of life. If the flow of blood is stopped, life will stop. Heart is the main organ of cardiovascular system and it is responsible for distributing blood all over human body. Heart diseases are categorized as the “leading cause of death” in United states. (Reference:CDC.gov). This explains that most people in the united stated die because of heart diseases and elaborates the importance of heart and Cardiovascular system for human body.

Introduction to Respiratory System

Organs of human Respiratory System

Functions of Respiratory System

1. GASEOUS EXCHANGE: Main function of respiratory system is gaseous exchange. Through respiratory system new air is always brought into the body and used air is expelled out. In this way oxygen is gained and carbon dioxide is lost by the body.
2. EXCRETION OF CARBON DIOXIDE: Respiratory system is the major system for excretion of carbon dioxide from the body. Carbon dioxide is produced as a result of metabolic break down of carbohydrates in body and must be eliminated quickly. Carbon dioxide is brought to the lungs by blood and is lost from the lungs through gaseous exchange with fresh air in lungs.
3. OXYGENATION OF BLOOD: Oxygen is required by the body for break down of food and must be continuously supplied for continuous supply of energy. Supply of oxygen is maintained by respiratory system.

Introduction to Nervous System 

Nervous System 

(Source: TheEmirr/Wikipedia)

Nervous system is the chief controlling and coordinating system of the body. It controls and regulates all voluntary and involuntary activities of human body. There are three characteristic properties of nervous system of human body; Sensitivity, Conductivity and Responsiveness

Neuron is the unit of Nervous System 

The structural and functional unit of nervous system is called neuron. It is a special type of cell with a cell body and cell processes. 

Parts of Nervous System 

Nervous system of human body is divided broadly into two parts; Central Nervous System (CNS) and Peripheral Nervous System (PNS)
CENTRAL NERVOUS SYSTEM (CNS) : Central nervous system includes brain and spinal cord.
PERIPHERAL NERVOUS SYSTEM (PNS) : Peripheral nervous system includes all the parts of nervous system except brain and spinal cord. It is further divided into two components; Somatic nervous system and Autonomic nervous system.

Nerves

Nerves are solid cords composed of bundles of nerve fibers (each nerve fiber is an axon with its coverings) bound together by connective tissue. Nerves are of two types; Spinal nerves and Cranial Nerves.
Spinal Nerves: Spinal nerves arise from the spinal cord. There are 31 pairs of spinal nerves in human body.
Cranial NervesCranial nerves arise from the brain. There are 12 pairs of cranial nerves in human body. 

Functions Nervous System 

1. CONTROL OF ALL BODY FUNCTIONS: Nervous system is the master system of human body. It controls the activity of all other systems in such a way that all the systems collectively make a human being. Without a controlling system, there is no concept of life because in such case there will be no coordination between different body functions and they will all act separately. Nervous system not only controls the voluntary functions of human body that are directed by human will, but it also controls those functions that are below the level of consciousness of human beings. Control of a function means that the intensity of that function can be increase or decreased according to the demands of human body.
2. COORDINATION OF DIFFERENT BODY ORGANS: Nervous system not only produces coordination between different systems, but also between different organs of a system. To form an organ system, role of the component organs must also be coordinated. So nervous system is not only important for formation of an organism by different organ systems, but also for formation of a system by different organs of human body.

Introduction to Muscular System 

Muscular system is the system of Human Body that provides motor power for all movements of body parts. Muscular system is composed of special tissue called muscular tissue. Muscles have the ability to contract actvely to provide the force for movements of body parts. Muscular system is an important system of human body because without it, life will completely stop. Muscles produce not only those movements that are under the control of our will and that we can see and feel, but also those movements that are responsible for activities like breathing, digestion of food, pumping of blood etc.

Muscular System

Muscles:

Muscles are body tissues that provide the force for all body movements. They are made of special types of cells. For details of structure and types of muscles, please see the basic anatomy article “”. For details of microscopic structure of muscles, pleas see the histology article “”.

Types of muscles:

Muscles are basically of three types; Skeletal Muscles, Smooth Muscles and Cardiac Muscles.

Skeletal Muscles:
Skeletal muscles form most of the human body weight. They are under the control of human will and all body movements occurring by our will are produced by skeletal muscles. They are called skeletal muscles because they are almost always found attached to the skeleton and produce movements in different parts of the skeleton.

Skeletal Muscle

Smooth Muscles:
Smooth muscles form the soft body organs like stomach, intestine, blood vessels etc. They are not under the will of human beings and are responsible for unconscious body activities like digestion of food. They are called smooth muscles because when seen under the microscope, they do not have any striation in contrast to the other two types of muscles.

Smooth Muscle

Cardiac Muscles:
Cardiac muscles are exclusively found in human heart and no where else. They are extremely strong and powerful muscles. They are not under the control of human will and are involuntary. The pumping of blood by human heart is because of the force provided by the contraction of cardiac muscles.

Cardiac Muscle

Functions of Muscular System 

Muscular system has the following important functions in human body;

1. MOVEMENTS OF BODY PARTS: Skeletal muscles are responsible for all voluntary movements of human body parts. They provide the force by contracting actively at the expense of energy. In other words, muscles are motors of body where chemical energy of food is converted into mechanical work.
2. STABILITY AND POSTURE: Skeletal muscles stabilize human skeleton and give a proper posture to human beings. Some joints of human body are weak and they require the support of muscular system to achieve stability. Skeletal muscles are very important for such joints.
3. HEAT PRODUCTION: A large share of body’s energy is used by muscular system. As a result of high metabolic rate, muscles produce great amount of heat in the body. Heat produced by muscles is very important in cold climates.
4. CIRCULATION: Cardiac muscles provide the main force for circulation of blood throughout human body. The regular pumping of heat keeps the blood in motion and nutrients are readily available to every tissue of human body.
5. HELP IN DIGESTION: Smooth muscles of organs like stomach and intestine help the digestive system in the process of digestion of food.

Human Skeleton

Components of Human Skeleton

Human skeleton is composed of three main components; Bones, Associated cartilages and Joints.

Bones:

Bone is a tough and rigid form of connective tissue. It is the weight bearing organ of human body and it is responsible for almost all strength of human skeleton. For more details visit: Basic anatomy article; “Bone“.

Cartilages:

Cartilage is also a form of connective tissue but is not as tough and rigid as bone. The main difference in the cartilage and bone is the mineralization factor. Bones are highly mineralized with calcium salts while cartilages are not. For more details visit: Basic anatomy article; “Cartilage and its types“.

Joints:

Joints are important components of human skeleton because they make the human skeleton mobile. A joint occurs between “two or more bones”, “bone and cartilage” and “cartilage and cartilage”. For more details visit: “Joints”

Divisions of Human Skeleton

Human skeleton can be divided into two divisions.

Axial Skeleton:

Axial skeleton forms the axis of human body. It consists of Skull, vertebral column and thoracic cage.

• Skull: Skull is that part of human skeleton that forms the bony framework of the head. It consists of 22 different bones that are divided into two groups: bones of cranium and bones of face. For more details, visit:””
• Vertebral Column: It is a flexible column of vertebrae, connecting the trunk of human body to the skull and appendages. It is composed of 33 vertebrae which are divided into 5 regions: Cervical, Thoracic, Lumbar, Sacral, and Coccygeal. 
• Rib Cage: It is a bony cage enclosing vital human organs formed by the sternum and ribs. There are 12 pairs of ribs that are divided into three groups: True ribs, False ribs, and Floating ribs.

• Shoulder Girdle: It attaches the upper limb to body trunk and is formed by two bones: clavicle and scapula.Clavicle is a modified long bone and is subcutaneous throughout its position. It is also known as the beauty bone. For more details on clavicle, visit:””Scapula is a pear shaped flat bone that contains the glenoid fossa for the formation of shoulder joint. It possesses three important processes: Spine of scapula, Acromion process and Coracoid process.
• Skeleton of Upper limb: The skeleton of each upper limb consists of 30 bones. These bones are: Humerus, Ulna, Radius, Carpals (8), Metacarpals (5), Phalanges (14).
• Pelvic Girdle: There are two pelvic girdles (one for each lower limb) but unlike the pectoral girdles, they are jointed with each other at symphysis pubis. Each pelvic girdle is a single bone in adults and is made up of three components: Ileum, Ischium and Pubis. For more details, visit “Hip Bone“.
• Skeleton of Lower limb: The skeleton of each lower limb consists of 30 bones. These bones are; Femur, Tibia, Patella, Tarsals (7), Metatarsals (5), Phalanges (14)

Functions of Human Skeleton

1. STRENGTH, SUPPORT AND SHAPE: It gives strength, support and shape to the body. Without a hard and rigid skeletal system, human body cannot stand upright, and it will become just a bag of soft tissues without any proper shape
2. PROTECTION OF DELICATE ORGANS: In areas like the rib cage and skull, the skeleton protects inner soft but vital organs like heart and brain from external shocks. Any damage to these organs can prove fatal, therefore protective function of skeleton is very important
3. LEVERAGE FOR MOVEMENTS: Bones of the human skeleton in all parts of body provide attachment to the muscles. These muscles provide motor power for producing movements of body parts. In these movements the parts of skeleton acts like levers of different types thus producing movements according to the needs of the human body.
4. PRODUCTION OF RED BLOOD CELLS: Bones like the sternum, and heads of tibia have hemopoeitic activity (blood cells production). These are the sites of production of new blood cells.