Pregnancy and childbirth
Main article: Pregnancy and childbirth
Body bricks
DNA
Main article: DNA
Molecules
Water
The water content in the human body ranges from 80% (in newborns) to 55% (in the elderly).
The least water in the bones is 32-35%. And most of all, not in the blood, as one might think, but in the brain - up to 90%. In her blood - about 80%.
Organic compounds
Collagen
- question-writer
Which proteins are the most in the body?
Between 25% and 35% of our body's proteins are collagens. They form the basis of connective tissue and provide its elasticity and strength: for example, the organic matrix of bone is 90% composed of collagen of the first type. In total, 28 types of collagen are known, which are encoded by 40 genes.
Cages
Somatic cells
Somatic cells (other Greek catfish - body) - cells that make up the body (catfish) of multicellular organisms and do not take part in sexual reproduction. Thus, these are all cells except gametes.
Mitosis (in the video below) is the process of indirect division of somatic cells, as a result of which two daughters with the same set of chromosomes are formed from one maternal cell.
Stem cells
Over the years, the stock of stem cells decreases and does not recover.
The embryo has 1 stem cell per 10 thousand cells, and in humans 60-70 years old, out of 8 million ordinary cells, only one is a stem.
Macrophages
Main article:: Macrophages
Macrophages - cells capable of absorbing and digesting foreign or harmful particles to the body: bacteria, remnants of destroyed cells, etc.
In the adult body, only 43% of human cells
In 2019, a report by English scientists showed that human cells make up only 43 percent of the total number of cells in the body.
The remaining 57 percent are bacteria, fungi and unicellular eukaryotes that live in our gut, mouth, skin and reproductive tract.
If we count all the cells, then we are 47% people. But this was not always the case - when we are born, there is more human in us, but in the very first years of our lives we are captured by colonies of bacteria. Over the course of our lives, starting with the embryo, there is a dynamic change in the number of microbes.
The video below shows the process of cell division.
The video below compares cell and microorganism sizes up to 1 mm. Most of them can read this text with you right now.
Physiology
Nervous system
Main article: Nervous system
Main article: Cysticercosis (finnosis) of the central nervous system
Reflexes
Pilomotor reflex lifts hairs on body
The reflex leading to "goose skin" is called the pilomotor reflex.
As a result of stimulation of sensational peripheral nerves emanating directly from the spinal cord, autonomic peripheral nerve endings are excited, which are responsible for the contraction of the smooth muscle of the hair follicles. By contracting, follicle muscles raise hairs on the body.
Why a person blushes when he is ashamed and urinates when he is scared
Redness occurs due to the expansion of the smallest blood vessels - capillaries. As a result, blood flashes to the skin and changes its color.
The vascular reaction of capillaries is associated with the peculiarities of their nervous regulation. A rush of blood to the skin is a manifestation of excitement, strong emotions. Worried, we get into a defense position, kind of defend ourselves. In such cases, the sympathetic nervous system, which is responsible for behavior in a situation of danger (stress), takes command of the processes in the body. Her work is independent of our consciousness. In a situation of danger, we usually have two behaviors: either fight or run away. In both cases, it is necessary to quickly put the body on alert. Performing this task, the sympathetic nervous system ensures the redistribution of energy in the body so that most of it received muscles: it accelerates breathing and heart rate, narrows blood vessels, slows down digestive processes, expands pupils.
Involuntary urination at the moment of fright is also associated with the adoption of a "state of combat readiness." So the body is trying to free itself from excess cargo so that it is easier for it to run and generally move.
Respiratory system
Lungs
Main article: Light man
Differences between human respiratory system and other animals
In humans, the most important role is played by the lungs with a complex system of vesicular formations - the alveoli.
In birds, the respiratory system is not the most advanced, but is considered one of the most complex among all groups of animals.
In insects, oxygen spreads through a special tracheal system, entering through specialized pores in the body (spiracles).
At rest, an adult performs approximately 16 respiratory movements in 1 minute. This happens approximately as shown in the video.
Sneezing
It is impossible to sneeze with your eyes open. As the study showed, during sneezing, so much pressure is formed that in case of non-closure of the eyes, they simply can "fly out" of the orbits. The speed of exhaled air when sneezing is on average 150 km/h.
Snore
Main article: Snoring
Tracheotomy
Main article: Tracheotomy
Circulatory system
Blood
Main article: Human blood
Heart
Main article: Human heart
Arteries
- The aorta is the largest artery in our body.
Immune system
Endocrine system
Main article: Thyroid gland
Main article: Ovaries
Hormones
Main article: Adrenaline
Main article: Testosterone
Digestive system
Hunger
Main article: Feeling hungry
Gullet
The process of fluid passing through the oral cavity and pharyngeal cavity.
Stomach
Main article: Stomach
Gallbladder
Main article: Gallbladder
Intestines
Main article: Intestines
Main article: Inflammatory Bowel Disease (IBD)
Main article: Bowel cancer (colorectal cancer)
Pancreas
Alcohol affects, first of all, the work of the liver and pancreas, which in turn has a negative effect on the skin.
Even periodic intake of wine, and in small doses, causes irreversible changes in the pancreas. And this is the main element of digestion. Many diseases are associated with the gastrointestinal tract. Generalizing, we can say that skin problems caused by alcohol consumption are primarily associated with the work of the pancreas, and through it with the entire intestine.
Liver
Main article: Liver
Urinary system
Kidneys
Main article: Kidneys
Sweat glands
The average person produces about 83 liters of sweat in his bed during the year.
Increased sweating
In September 2024, British therapist Ellie Cannon said that increased sweating can be both harmless and signal serious health problems. One of the diseases accompanied by excessive sweating is rosacea. In such cases, the skin can feel hot, and the body, trying to cool down, produces more sweat.
Cannon also noted that disorders in the thyroid gland can lead to increased sweating. The thyroid gland plays an important role in metabolism, and its dysfunction can manifest with a number of symptoms, including fatigue, weight change, depression, and muscle pain. In this case, excessive sweating becomes one of the possible signs of the disease. The Daily Mail wrote about this.
Bone system
Skeleton
This photo shows a curious comparison of a human skeleton and a gorilla.
The skeleton of man and gorilla has a common structure, but at the same time a number of important differences. The main differences are the shape and proportions of the skull, spinal column, the proportions and length of the limbs, the size of the chest and the shape of the pelvic bones.
Differences in the structure of the male and female skeletons
There are some differences in the structure of the skeleton of a man and a woman. In men, the skeleton is heavier, the skull is rougher and about 10% larger than the female. The forehead in men is more chamfered, the depressions and bulges are larger. The lower jaw is more massive and stronger.
The pelvis in women is wider, lighter and smoother. In men, the upper outlet of the pelvis is heart-shaped, and in women it is oval. Men have a deep iliac fossa, women have a shallow fossa. The man's sacrum is long, with strong curves, the tip of the coccyx is forward, and in women it is backward.
Skull
Main article: Human skull
Main article: Traumatic brain injuries (TBI)
Backbone
The spine is a very complex part of the human axial skeleton, consisting of 220 ligaments, 100 joints, 120 muscles, 24 free and 9-10 non-free vertebrae.
Spinal injuries
Joints
Main article: Joints
Bones
In infancy, we have much more bones than in old age. The newborn has 350 bones, and the adult has only 208.
Many of the children's bones subsequently fuse together. The collarbone is the last bone that fuses between 18 and 25 years old.
Bone tissue is approximately five times stronger than reinforced concrete, in terms of tensile resistance it slightly exceeds the resistance of oak, its strength approximately corresponds to the strength of cast iron.
Compact substance outside and spongy inside.]]
The tibia is the strongest in our body.
The tibia can withstand 4 tons of weight. This means that to crush the tibia with pressure, it takes about 4 thousand kilograms.
Bone diseases and injuries
Main article: Bone fractures
Marble disease is a rare hereditary disease manifested by diffuse compaction of the bones of the skeleton, brittle bones, insufficiency of bone marrow hematopoiesis.
Muscular system
There are about 640 muscles in the human body. About - because there can really be different numbers of them.
Facial muscles
There are 57 muscles on a person's face and most of them are involved in the formation of emotions.
A person uses 17 muscles when they smile and 43 when they frown.
Leg muscles
3D animation shows the complex interaction of leg muscles in time for walking.
Brushwork
The muscle of the hand is a complex complex of about 33 muscles. Most of them are located in the forearm and are connected by tendons to the phalanges of the fingers through several joints.
Not everyone has a long palmar muscle: in animals, it is used to release claws. A person does not use it, therefore, it was preserved in a rudimentary form in some people - only on one hand, and in some - it was not preserved at all.
Diaphragm
The diaphragm is the main respiratory muscle in the human body. Without the tension of this muscle, the lungs would not be able to expand sufficiently and provide the necessary oxygen supply.
This muscle is located directly under the lungs and attaches to the ribs, sternum and lumbar vertebrae.
Why muscles hurt after loads
Any organ requires energy for its work, which it extracts from organic molecules during the breathing process. As a result, nutrients are broken down to carbon dioxide and water, and the energy stored in them goes to the needs of cells. Oxygen for these purposes is delivered by blood.
Muscles are no exception to this rule. However, the mass of the quadriceps muscle alone in the average person is 2-4 kg, and the entire volume of available blood is only 1.5-2 liters. But all other organs, not only muscles, need blood.
Therefore, with intense physical activity, even with the maximum filling of muscles with blood, they still lack oxygen. And in such a situation, a backup mechanism for obtaining energy comes to the rescue, in which organic compounds are not completely broken down. Instead of carbon dioxide and water, lactic acid is formed.
It is the accumulation of lactic acid in the tissues that causes muscle pain, which people call crepature. Over time, this acid, like all metabolic products, is excreted from the body and the pain goes away.
Why most injections are on the buttocks
Because the gluteal muscle is very thick, and its upper outer quadrant lacks large vessels and nerve trunks.
This minimizes the risk of complications and increases the effectiveness of the injection.
Artificial muscles
Main article: Artificial muscles
Senses
Sight
Main article: Vision
What the ophthalmologist sees when he expands your pupils:
Hearing
Main article: Hearing
Taste
How are taste cells distributed on the tongue?
Previously popular was the scheme: the back of the tongue is sensitive to bitter, the tip to sweet, the side surfaces ahead to salty, and closer to the back to sour. All this is a common scientific mistake.
There are about 8,000 taste buds in our body. Each contains a complex of receptor cells that can isolate any of the five main flavors. The taste signal moves toward the brain by two craniocerebral nerves, one located at the back of the tongue and the other at the tip.
The version underlying the notion that different parts of the language react to taste differently was born from an incorrect translation of Henig's work into English, who wrote that different parts of the language are able to recognize all five tastes, but from different parts of the language impulses about different tastes move at different speeds.
Sense of smell
Main article: Smell
Skin
Main article: Human skin
Nails
Main article: Nails
Head
Hair
Main article: Hair
Main article: Gray hair
Nose
Nasal mucosa
The mucous membrane works thanks to microscopic cilia, which, oscillating at a rate of 20 vibrations per minute, drive the mucus in the right direction.
Cilia cannot be deceived - it is impossible to force them to drive mucus in the other direction, their movements are always directed towards the sinus joint. Doctors call this process "mucociliary clearance."
Teeth
Main article: Teeth
Lips
Body temperature
How our body maintains a normal temperature
Chemical reactions constantly occur in the body, as a result of which heat is produced. Muscle contractions also produce heat through friction.
Body temperature records
As of April 2019, 46.5 ° C is the highest body temperature recorded in 1980 in the United States. American Wil Jones (52) received heatstroke and was taken to hospital. The patient did not die and, after undergoing treatment, was discharged from the hospital three weeks later.
The lowest human body temperature was recorded in 1994 in two-year-old Carly Kozolofsky, who was in the cold for a long time. When doctors measured her body temperature, she was 14.2 ° C.
Voice and speech
Main article: Voice
Growth
Microbiome
Main article: Microbiome
The microbiome is trillions of microorganisms that include bacteria, fungi and viruses that 'live' inside and on the surfaces of our bodies.
Tail
In February 2020, it became known that in one of the hospitals in Baku, a 17-year-old boy had his "tail" 18 centimeters long removed.
The doctor noted that the 17-year-old guy went to the hospital with pain in the spinal pelvic region: "It was difficult for him to sit and dress." He also noted that such facts are not uncommon, but stressed that he was surprised why the parents reached such an age, because the child had a tail from birth, he just gradually grew.
The operation was performed under general anesthesia. During the preliminary examination, it was found that the process was not associated with the spine.
Food
Main article: Nutrition
Wound healing
Main Article: Wound Healing
Aging
Main article: Aging
How much the organs cost
The following are data for 2019 from various sources, mainly interviews with "black" doctors and their patients taken in the previous 20 years.
- Bone marrow - 23 thousand dollars per gram (in the body of an adult man on average 2.5 kg, that is, for everything you can help out 57.5 million - but this is an absolute utopia)
- Cornea - $350 thousand
- Liver - 200 thousand dollars or more
- Lungs (2 pcs) - up to 200 thousand dollars
- Pancreas - $ 70 thousand
- Kidneys (2 pcs) - up to 50 thousand dollars
- Genital glands, male or female - up to 15 thousand dollars.
If you are dead at the time of organ removal, the price drops by about half.
Death of man
Main article: Death of a person
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