Lungs

The lung (adjectival form: pulmonary) is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart. Their principal function is to transport oxygen from the atmosphere into the bloodstream, and to release carbon dioxide from the bloodstream into the atmosphere. This exchange of gases is accomplished in the mosaic of specialized cells that form millions of tiny, exceptionally thin-walled air sacs called alveoli.

Respiratory System :

In humans and other animals, 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. This exchange process occurs in the alveolar region of the lungs.

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.

Heart

The heart is a myogenic muscular organ found in all animals with a circulatory system (including all vertebrates), that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions. The term cardiac (as in cardiology) means "related to the heart" and comes from the Greek καρδιά, kardia, for "heart".


The Human Heart:

The human heart has a mass of between 250 and 350 grams and is about the size of a fist. It is located anterior to the vertebral column and posterior to the sternum.

It is enclosed in a double-walled sac called the pericardium. The superficial part of this sac is called the fibrous pericardium. This sac protects the heart, anchors its surrounding structures, and prevents overfilling of the heart with blood.

Blood

Blood - is a specialized bodily fluid that delivers necessary substances to the body's cells (in animals) – such as nutrients and oxygen – and transports waste products away from those same cells.


Functions :

Blood performs many important functions within the body including:

• Supply of oxygen to tissues (bound to hemoglobin, which is carried in red cells)
• Supply of nutrients such as glucose, amino acids, and fatty acids (dissolved in the blood or bound to plasma proteins (e.g., blood lipids))
• Removal of waste such as carbon dioxide, urea, and lactic acid
• Immunological functions, including circulation of white blood cells, and detection of foreign material by antibodies
• Coagulation, which is one part of the body's self-repair mechanism (blood clotting after an open wound in order to stop bleeding)
• Messenger functions, including the transport of hormones and the signaling of tissue damage
• Regulation of body pH
• Regulation of core body temperature
• Hydraulic functions

Blood Vessel

The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and the tissues; and the veins which carry blood from the capillaries back toward the heart.

The Eyes

The Eye - are organs that detect light, and convert it to electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement.

Structures of the Eye (External) :

• Orbit - cone-shaped cavity formed by the skull, the houses and protects the eyeball, padded with fatty tissue, cushiosn and protects the eye from injury


• Lacrimal apparatus - produces tears


• Lacrimal gland - transports tears


• Conjunctiva - protective membrane, lines the exposed surface of the eyeball.

Structures of the Eye (Internal) :

• Aqueous humor - water humor, bathes the iris, pupil, and lens,
• Vitreous humor - clear, jelly-like fluid, occupies the entire eye cavity behind the lens

The Ears

The Ear - is the anatomical organ that detects sound. Structures of the Ear:

• External


• Middle/ Tympanic cavity


• Inner/ Labryinth

External Ear:

- it is the outer projection

- has several shapes and sizes

- it includes the pinna (auricle), auditory canal (external auditory) and the ear drum (tympanic membrane)

Contains:

• Pinna ( auricle) - collects and directs sound waves


• Auditory canal (external auditory) - contains cerumen (earwax)


• Ear drum (tympanic membrane) - it is where it ends and middle ear begins.

Middle Ear:

- the space containing the smallest bones of the body

Contains:

• hammer (Malleus) - has a long process that is attached to the mobile portion of the ear drum.


• Anvil (Incus) - it is the bridge between the malleus and stapes.


• Stirrup (Stapes) - is the smallest named bone in the human body.

The Eustachian tubes - allows air pressure on either side of the ear drum to be equalized, and it is also within the middle ear.

Inner Ear:

- is encased in the hardest bone of the body.

Contains:

• Cochlea - bony spiral, snaily shell-shaped, and contains perilymph for transmitting sounds


• Vestibule - is the central part of the osseous labyrinth


• Semicircular canals - are three half-circular, interconnected tubes located inside each ear.