Cardiovascular (heart & circulatory system)
The heart, a remarkable muscle, beats nearly three billion times in an average person's lifetime. The blood circulation system is extensive, with vessels that would stretch more than twice around the Earth. This intricate "plumbing" system ranges from large arteries to microscopic capillaries, demonstrating precise engineering.
If you lined up the capillaries in one adult end to end, they would stretch 100,000 miles, which is four times the circumference of the Earth at the equator (25,000 miles). These tiny vessels supply oxygen and nutrients to the body’s tissues.
The aorta, the largest artery in the body, has a diameter comparable to that of a garden hose. In contrast, capillaries are so tiny that it takes ten of them to match the thickness of a human hair.
A human heart beats 100,000 times a day, pumping 2,000 gallons of blood.
Males have 12 pints of blood, while females have 9 pints.
Lymphatic/Immune (defends against pathogens)
When we get injured or sick, our bodies have sophisticated mechanisms for healing and fighting off infections. The immune system's ability to recognize and combat a wide variety of pathogens is often seen as evidence of design.
There are between 400-800 lymph nodes in the body constantly monitor and filter the lymph to remove toxins, waste, and pathogens.
Lymphatic fluid runs everywhere blood flows throughout your body.
Respiratory (absorb oxygen & remove CO2, sinus)
The respiratory system features lung sacs with a surface area comparable to a tennis court.
Integumentary (skin, sweat, hair, nails, oil glands)
You lose 200 million skin cells every hour, or 5 billion in one day.
Endocrine (glands & organs that make hormones)
Digestive (absorb nutrients & remove waste)
Urinary/Excretory (kidneys, ureters, bladder)
The liver performs over 500 functions.
Skeletal (206 bones)
Nervous (brain, spine, processes info from senses)
Central Nervous System (Brain & Spinal Cord)
Our cognitive and communicative abilities far surpass those of other animals. The human brain's capacity for complex thought, language, and problem-solving is often viewed as evidence of design.
Periphery Nervous System (Nerves, Sensory Organs and Receptors, Ganglia. Senses: Eyesight, Hearing, Touch, Taste, Smell)
In just one square inch of skin, there are 12 feet of nerve fiber, 600 pain sensors, 1300 nerve cells, 9000 nerve endings, 36 heat sensors, 75 pressure sensors, 15 feet of blood vessels, 4 yards of nerves, 650 sweat glands, 100 oil glands, 1,500 sensory receptors, and more than 3 million cells with an average life span of 26 days that are constantly being replaced. The nervous system uses 43 pairs of nerves to transmit messages at speeds up to 200 MPH. The brain, more complex than any computer, contains over 100 billion nerve cells.
The eyes can distinguish more than eight million shades of color.
The ears can differentiate over 300,000 distinct sounds.
Reproductive
The process of human reproduction, from conception to birth, is incredibly complex and precise. The development of a new human being within the womb is often cited as an example of intricate biological engineering.
An egg is size of a grain of sand!
Muscular
The human body's intricate design and functionality suggest the work of an intelligent creator rather than random chance. The incredibly complex design of the human body serves as powerful evidence for a creator, much like finding a sophisticated computer on Mars would imply intelligent design rather than spontaneous evolution. These remarkable features of the human body point to a level of complexity and precision that many argue could not have occurred by chance, suggesting the existence of an intelligent designer or God.
Cells: We have trillions of cells in our body. Cells are the basic building blocks of all living things. They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. Cells also contain the body’s hereditary material and can make copies of themselves.
DNA: (deoxyribonucleic acid) is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA). Mitochondria are structures within cells that convert the energy from food into a form that cells can use. The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.
Genes: A gene is the basic physical and functional unit of heredity. Genes are made up of DNA. Some genes act as instructions to make molecules called proteins. However, many genes do not code for proteins. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases. The Human Genome Project, which worked to determine the sequence of the human genome and identify the genes that it contains, estimated that humans have between 20,000 and 25,000 genes. Every person has two copies of each gene, one inherited from each parent. Most genes are the same in all people, but a small number of genes (less than 1% of the total) are slightly different between people.
Chromosomes: In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure. Chromosomes are not visible in the cell’s nucleus—not even under a microscope— when the cell is not dividing. In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females. Females have two copies of the X chromosome, while males have one X and one Y chromosome.