The human body is everything that makes you human. It is composed of many systems that work together to perform a variety of functions and to keep the body at homeostasis. Apart from the parts we can see, which are the head, neck, legs and outer structures, there are also organs on the inside, mainly the brain, which runs everything from the release of hormones, to controlling voluntary actions, to turning on the flight-or-fight response.
The basic unit of which the human body is made is called the cell, and when cells are grouped, they become tissue, then organs including the heart, the kidneys, the liver, the stomach etc., and finally organ systems including the digestive system, the cardiovascular system, the reproductive system, and the respiratory system.
How well do you know the human body, the same body you've been in from the time you were born? Are you a person who only knows its basic functions like the external organs, or are you an expert who should seriously consider going to medical school? If you would like to find out where on the scale of a novice to genius you would fall, then this is the quiz you need to take.
When humans are born, they have approximately 300 bones, but as they age, many them fuse together (approximately one third), leaving the adult skeleton with 206 bones.
Red blood cells are produced in the bone marrow and are controlled by a hormone known as erythropoietin that is released from the kidneys. The immature cells start there (bone marrow) and after maturation, they are released into the bloodstream for transportation of oxygen.
The small intestine is almost 7 meters in length, and it consists of three distinct parts: the duodenum, the jejunum and the ileum. Most of the chemical digestion takes place in the duodenum while absorption takes place in the jejunum and ileum through the villi.
The posterior pituitary, also known as the neurohypophysis, is the posterior lobe of the pituitary gland. It is responsible for storing and releasing two hormones: oxytocin and anti-diuretic hormone (vasopressin), which are responsible for uterine contraction and regulation of water in the body respectively.
Comprising of approximately 22 square feet of space and weighing about 8 to 20 pounds, the skin covers the outer surface of the human body, protecting it from microbes and the elements as well as regulating body temperature.
Nucleotides are the building blocks of DNA, and they contribute to both the structure of DNA and RNA. They form base pairs that are held together by hydrogen bonds either in guanine-cytosine pairing, adenine-thymine as well as adenine-uracil in RNA.
There are three types of joints in the human body: fibrous, cartilaginous and synovial. Synovial joints are further broken down into six different categories, one of which is the hinge joint. They are formed between two bones which only move along one axis to either flex or extend. One example of this joint is the knee joint.
The DNA strand consists of two strands of bases that wind around each other in a double helix formation. In 1953, James Watson and Francis Crick first described the structure of the molecule, which later earned them a Nobel Prize in Medicine.
The spinal column, also called the vertebral column or backbone, is a part of the vertebral column that has many functions, including protecting the spinal cord, transmitting body weight to help with walking as well as providing attachments for various muscles.
In newborns, the body constitution of water is approximately 70%, but as we become adults, it decreases to an average of 60% in males and 50% in females. Other forces like age and body fat composition also affect these figures.
The primary function of the immune system is to defend the body against pathogens including parasites, bacteria, viruses or fungi which have entered the body. Some of the key players in this system are the spleen, which stores white blood cells, the thymus, which helps to develop t-lymphocytes, and the lymph nodes, which filter for harmful substances.
All veins except for the pulmonary veins and the umbilical veins in babies carry deoxygenated blood. This blood is returned to the lungs where gas exchange occurs and then travels through arteries.
There are four main blood groups - A, B, AB, and O, which are determined by the genes that you inherit from your parents. If you take the RHD negativity and positivity into consideration, there are a total of eight blood groups.
The spinal column is made up of 31 segments divided into five groups of bones, named after their location. The cervical contains seven bones, the thoracic contains 12, the lumbar has five, the sacrum with five and the coccyx with four.
The stapes (bone) and the stapedius (muscle) are the smallest bones and muscles found in the human body, both of which are located in the ear. The stapes is one of the three ossicles in the middle ear, and the stapedius stabilizes it.
The suprachiasmatic nucleus is a small region located in the hypothalamus of the brain, which is responsible for controlling the circadian rhythm also known as the sleep-wake cycle.
The lacrimal glands are a pair of small exocrine glands, one located in the upper lateraled region of each eye orbit, and are responsible for tear production. The pineal gland produces melatonin - for sleep, the lingual gland helps to produce saliva, and the thyroid glands produce thyroid hormone.
Red blood cells contain a molecule known as hemoglobin, which is made of heme subunits. These heme subunits are composed of the iron molecules, which look red as a result of the interaction with oxygen. Deoxygenated blood has a blue appearance.
Encephalitis is the inflammation of the brain, which is most commonly caused by a viral infection and varies in severity. Myocardial infarctions (heart attacks), coronary artery disease and unstable angina are all cardiovascular disorders.
Bile is a greenish-yellow liquid, which is necessary for the digestion of fats and other toxins. The liver produces between 0.25 to 1 liter a bile a day and is later stored in the gallbladder until it is released.
The cranial nerves are 12 pairs of nerves directly connected to the brain, and they have either sensory or motor functions, while some have both. The olfactory, optic and vestibulocochlear are sensory nerves while the oculomotor, trochlear, abducens, accessory and hypoglossal are motor nerves. All the others - trigeminal, facial, glossopharyngeal and vagus - have dual functions.
The pancreas is an organ located in the abdomen, which plays an integral role in both the digestive and endocrine systems. In digestion, it releases enzymes that help to digest proteins as well as break down fat. In the endocrine system, it releases hormones (insulin and glucagon), which relate to blood sugar levels.
Acetylcholine (Ach) is an organic neurotransmitter that is most often seen at the neuromuscular junctions where it is released to activate muscles.
The esophagus is a muscular tube which connects the throat to the stomach. When food is swallowed, it passes through the structures with the aid of peristaltic movements until it reaches the stomach.
The testicles, sometimes called testes, are male reproductive organs whose function is to produce sperm and testosterone. In the female, they are synonymous with the ovaries.
The word pericardium, when dissected, is broken up into two fragments, peri, which means "around," and cardium, which refers to the heart. It is a double-walled sac which encloses the heart and consists of an outer fibrous layer and an inner serous layer.
The aorta is the largest artery in the body and begins at the top of the left ventricle of the heart extending all the way down to the abdomen where it divides into two smaller arteries.
The kidneys filter unwanted substances from the blood with the final product being urine that exits the body. From the kidneys, it passes into the ureters, which then go to the bladder where it is stored. It is finally excreted from the body through a passageway known as the urethra.
Tissues are defined as a group of cells that have a similar structure and act together to perform a specific structure. Cells are the building blocks of tissues, while a similar group of tissues forms an organ, and different organs form an organ system.
In response to acute stress, the body goes through physiological changes in which the sympathetic nervous system is activated, and the parasympathetic nervous system is shut down. This leads to increased heart rate, flushing of the skin, dilation of the pupils, relaxation of the bladder and inhibition of digestion. This is known as the flight-or-flight response.
The iris is a thin circular structure responsible for controlling the amount of light that reaches the retina by controlling two groups of smooth muscle. It is also the colored portion of the eye.
Ribs are long curved bones that form the rib cage and serve to protect the internal organs of the thorax (lungs, heart, etc.) There are 12 pairs of ribs, seven of which are called true ribs because they attach to the sternum. The 8th through 12th rib do not, so they are called false ribs.
The lungs are the main organ in the respiratory system and they are responsible for the gaseous exchange of oxygen, carbon dioxide, and other gases between the outside and the bloodstream. Humans have two lungs located on either side of the heart - the left lung containing two lobes and the right having three.
The gastrocnemius is a muscle located in the posterior (back) lower leg and one of the two major calf muscles. It is responsible for plantar flexion of the foot at the ankle joint and for flexion of the leg at the knee joint.
The adrenal glands are two triangular shaped glands that produce hormones which help to regulate the immune system, blood pressure, metabolism and a host of other functions. They are suprarenal organs, which means that they sit on top of the kidneys.