A colon, why?
In the large intestine (colon) resorption takes place of the remainders of the digested food and liquid, which makes the stool thicker and makes it gliding by the addition of mucus. The wall of the large intestine consists of the typical layers for the digestive tract: the mucosa, submucosa, muscularis and serosa. The lumen is subdivided by numerous crescent-shaped folds.
The mucous membrane of the large intestine is a single layer of thick cylindrical epithelium, which consists of numerous absorptive cells with a brush-like edge, amongst which goblet cells are embedded. The latter do not have a brush-like edge and produce mucus especially at the bottom of the tubular crypts. The crypts are straight tubular and run down from the surface through the mucosa. With the depth, the number of goblet cells increases, while the absorptive cells become flatter and diminish in number. The connective tissue of the lamina propria fills the space between the crypts. The muscularis mucosa is composed of an inner ring and an outer layer of smooth musculature. The submucosa is a loose connective tissue with solitary lymph nodes, larger blood vessels and groups of fat cells.
Learning from rats
The rat proves science daily services in areas such as surgery, cancer, heart disease, embryology, diabetes, paraplegia, addiction etc. In research, in the twentieth century, the rat has been partially displaced by the mouse, which is smaller, propagates faster and is easier to manipulate genetically. But because of its greater pharmacological similarity with humans and his larger body - useful in surgeries – the rat has maintained himself in the lab.
Laboratory rats have bicornuate uteri and weigh between 200 and 400 g. There are numerous different "strains" with slightly different gestational features. A commonly used animal is the Wistar rat; it is white in color. Another important strain is the Sprague Dawley rat, but many more well-known strains are also employed for research purposes.
Rat embryos do have the advantage of being much larger than mouse embryos and are easy to breed. Both rodents, rat and mouse, with whom humans had a common ancestor 75 million years ago, roughly possess as many genes as we have: 25 to 30 000. But deep down the rat seems to be the most like us: 90 percent of its genes have a human counterpart. For this analyses, the researchers have used the brown rat, or sewer rat.
>The structure of the eyes is in its basic form the same for all mammals. The function and operation of the eyes of mammals is thus also broadly similar.
The retina which is located on the back of the eye, is composed of very closely spaced light-sensitive cells that are in connection with the brains via the optic nerve. The light signals that reach the light-sensitive cells, are transferred to the brains via the optic nerve. The brains takes these signals and translates them into the picture what is happening before our eyes.
Colors make us distinguish things around us better. But how do our eyes recognize colors and can animals observe different colors as well? The electromagnetic waves from the visible range are of different lengths. The longer waves are perceived by our eyes as red and orange, the shorter ones as green and blue. The light-sensitive cells of the retina consist of two types, rods and cones. The rods cannot distinguish color, but are on the other hand light sensitive and also detect very small light intensities. The cones do convert the received wavelengths in colors. Some mammals, in particular primates, have three different kinds of cones. One is sensitive to blue, the second is sensitive to green, and the third cone is sensitive to yellow-green and red. The brains process them into multicolored images. The cones can only process the colors when light is strong enough. That's why at night everything is seen in gray tones. Maybe it's because of that, it has long been assumed that animals that are active at night, like cats, could not recognize colors. We now know that all mammals are able to see colors to some extent.
Extremely tiny but very useful‘hair’
>Ciliated epithelium is a type of bodily tissue that is lined with “ciliated” cells, which are basicallycells that have small, hair-like protrusions known as “cilia” that can either help the cells movealong the tissue or can help debris and waste move along the surface of the cells. Cilia typicallymove in one direction in a wavelike pattern, which allows the cells to sweep away debris, directthe flow of particles, and create a current. Tissues in this category are most common in thenasal and respiratory passageways, and are one of the main reasons mucus flows and carriesout dead cells when a person has a cold. They occur in many places, though, including thebrain, digestive system, and reproductive tract. Scientists usually categorize this sort ofepithelium based on where exactly it is, as well as its main function.
Red human blood cells in dark field illumination
It's safe stay under your skull
The type of most bones of the human skull is flat bone. Flat bones are bones whose principle function is either extensive protection or the provision of broad surfaces for muscular attachment. These bones are expanded into broad, flat plates, as in the cranium (skull), the ilium (pelvis), sternum and the rib cage.
In the cranial bones, the layers of compact tissue are familiarly known as the tables of the skull; the outer one is thick and tough; the inner is thin, dense, and brittle, and hence is termed the vitreous table. The flat bones in the skull are firmly connected to each other by means of seams.
Flat bones are composed of two layers of compact bone enclosing between them a variable quantity of cancellous bone,
which is the location of red bone marrow. In an adult, most red blood cells are formed in the marrow of flat bones. This
intervening cancellous tissue is called the diploë, a spongy bone structure.
Geographically, the bones of the skull can be divided into two parts. The part that protects the brains is called the cranium.
Its primary purpose is to protect the brain. The part that forms the face is called the facial skull.
Have a look in your thigh bone The femur, or thigh bone, is the longest, heaviest, and strongest bone in the entire human body. All of the body’s weight is supported by the femurs during many activities, such as running, jumping, walking, and standing. Extreme forces also act upon the femur thanks to the strength of the muscles of the hip and thigh that act on the femur to move the leg. The femur is classified structurally as a long bone and is a major component of the appendicular skeleton.
ProstateThe prostate gland is shaped like a donut, weighs about an ounce and is the size of a chestnut. It consists 30% muscular tissue and 70% glandular tissue.
SmokingLung cancer is the most common form of cancer caused by smoking. More than 80% of cases of lung cancer are due to smoking. Cigarette smoke contains many chemicals that interfere with the body's method of filtering air and cleaning out the lungs. The smoke irritates the lungs and leads to overproduction of mucus. It also paralyses the cilia - tiny hair-like structures that line the airways and clean out dust and dirt. Paralysis of the cilia means mucus and toxic substances accumulate, resulting in congestion of the lungs. This extra mucus means smokers are more likely to suffer from chronic bronchitis and what is known as 'smoker's cough'. Cigarette smoke is one of the best known triggers of asthma. When people suffer from asthma their inflamed air passages, which are very sensitive, narrow when exposed to cigarette smoke. This causes an asthma attack. Long term exposure of the lungs to the irritants in tobacco smoke destroys the normal lung structure. The elastic walls of the small airways within the lungs are broken down. This reduces the amount of lung tissue available for the transfer of oxygen from the air to the blood. This condition is called emphysema. Some degree of emphysema is found in almost all people who are long-term smokers, however the severity will vary depending on the amount of cigarettes smoked, and the number of years the individual smokes. Damage to the lung tissue is irreversible. Emphysema can be prevented by not smoking, avoiding anything that will irritate the lungs such as dust and cold air, and ensuring any chest infections such as flu and bronchitis are treated properly.