Eye anatomy

The human eye is the organ which gives us the sense of sight, allowing us to observe and learn more about the surrounding world than we do with any of the other four senses.  We use our eyesreading, working,  writing a letter, driving a car,watching televisionand in countless other ways.The eye is a slightly asymmetrical globe, about an inch in diameter. The front part of the eye (the part you see in the mirror) includes:
1.The iris.
2.The cornea.
3.The pupil.
4.The sclera.
5.The conjunctiva.

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Cardiovascular system

Cardiovascular System: 

The cardiovascular system includes the heart and the blood vessels. 

The heart pumps blood, and the blood vessels channel and deliver it throughout the body.

 Arteries carry blood filled with nutrients away from the heart to all parts of the body.

 The blood is sometimes compared to a river, but the arteries are more like a river in reverse.

 Arteries are thick-walled tubes with a circular covering of yellow, elastic fibers, which contain a filling of muscle that absorbs the tremendous pressure wave of a heartbeat and slows the blood down.

This pressure can be felt in the arm and wrist - it is the pulse.

 Eventually arteries divide into smaller arterioles and then into even smaller capillaries, the smallest of all blood vessels. One arteriole can serve a hundred capillaries.

 Here, in every tissue of every organ, blood's work is done when it gives up what the cells need and takes away the waste products that they don't need. Now the river comparison really does apply.

 Capillaries join together to form small veins, which flow into larger main veins, and these deliver deoxygenated blood back to the heart.

 Veins, unlike arteries, have thin, slack walls, because the blood has lost the pressure which forced it out of the heart, so the dark, reddish-blue blood which flows through the veins on its way to the lungs oozes along very slowly on its way to be reoxygenated.

 Back at the heart, the veins enter a special vessel, called the pulmonary arteries, into the wall at right side of the heart. It flows along the pulmonary arteries to the lungs to collect oxygen, then back to the heart's left side to begin its journey around the body again.

The heart has four chambers that are enclosed by thick, muscular walls.

 It lies between the lungs and just to the left of the middle of the chest cavity. The bottom part of the heart is divided into two chambers called the right and left ventricles, which pump blood out of the heart.

 A wall called the interventricular septum divides the ventricles.

                              The upper part of the heart is made up of the other two chambers of the    heart, called the right and left atria.

 The right and left atria receive the blood entering the heart. A wall called the inter atrial  septum divides the atria, and they're separated from the ventricles by the atrioventricular  valves. The tricuspid valve separates the right atrium from the right ventricle, and the mitral  valve separates the left atrium and the left ventricle.

            Two other heart valves separate the ventricles and the large blood vessels that carry blood leaving the heart. These valves are called the pulmonic valve, which separates the right ventricle from the pulmonary artery leading to the lungs, and the aortic valve, which separates the left ventricle from the aorta, the body's largest blood vessel.

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Anatomy of the Shoulder

The two main bones of the shoulder are the humerus and the scapula (shoulder blade).

The joint cavity is cushioned by articular cartilage covering the head of the humerus and face of the glenoid. The scapula extends up and around the shoulder joint at the rear to form a roof called the acromion, and around the shoulder joint at the front to form the coracoid process. Ligaments connect the bones of the shoulder, and tendons join the bones to surrounding muscles. The bicepstendon attaches the biceps muscle to the shoulder and helps to stabilize the joint.The end of the scapula, called the glenoid, meets the head of the humerus to form a glenohumeral cavity that acts as a flexible ball-and-socket joint.The joint is stabilized by a ring of fibrous cartilage surrounding the glenoid called the labrum.

Ligaments connect the bones of the shoulder, and tendons join the bones to surrounding muscles. The biceps tendon attaches the biceps muscle to the shoulder and helps to stabilize the joint.The end of the scapula, called the glenoid, meets the head of the humerus to form a glenohumeral cavity that acts as a flexible ball-and-socket joint.The joint is stabilized by a ring of fibrous cartilage surrounding the glenoid called the labrum.

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Human anatomy nose

The visible part of the human nose is the protruding part of the face that bears the nostrils.
 The shape of the nose is determined by the ethmoid bone and the nasal septum,
which consists mostly of cartilage and which separates the nostrils.
 On average the nose of a male is larger than that of a female.
The nasal root is the top of the nose, forming an indentation at the suture where the nasal bones meet the frontal bon.

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Respiratory system

The respiratory system is the anatomical system of an organism that introduces respiratory gases to the interior and performs gas exchange.

 In humans and other mammals, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles.

 Molecules of oxygen and carbon dioxide are passively exchanged, by diffusion, between the gaseous external environment and the blood.

Other animals, such as insects, have respiratory systems with very simple anatomical features, and in amphibians even the skin plays a vital role in gas exchange.

 Plants also have respiratory systems but the directionality of gas exchange can be opposite to that in animals.

The respiratory system in plants also includes anatomical features such as holes on the undersides of leaves known as stomata.

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The human brain is the center of the human nervous system.

The human brain is the center of the human nervous system.

It has the same structure as the brains of other mammals,

but is larger than expected on the basis of body size among other primates.

Estimates for the number of neuronsin the human brain range from 80 to 120 billion.

Most of the expansion comes from the cerebral cortex.

Fig: CNS

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Human anatomy

The human brain is the center of the human nervous system.

It has the same structure as the brains of other mammals,

but is larger than expected on the basis of body size among other primates.

Estimates for the number of neuronsin the human brain range from 80 to 120 billion.

Most of the expansion comes from the cerebral cortex, especially the frontal lobes,

which are associated with executive functions such as self-control, planning, reasoning, and abstract thought.

The portion of the cerebral cortex devoted to vision is also greatly enlarged in human beings,

and several cortical areas play specific roles in language,

a skill that is unique to humans.

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