I DID NOT MAKE THIS. This is from a website called Brainscape, “15 Human biology basics everyone should know”
1. The human body has 12 systems
The 12 human body systems are the cardiovascular system, the digestive system, the endocrine system, the immune system, the integumentary system, the lymphatic system, the muscular system, the nervous system, the reproductive system, the respiratory system, the skeletal system, and the urinary system.
All of these systems work together to ensure that our bodies work correctly:
The cardiovascular (or circulatory) system transports blood, oxygen, and nutrients throughout the body.
The digestive system takes in and processes food.
The endocrine system produces hormones that regulate metabolism, growth and development, tissue function, sexual reproduction, sleep, and mood.
The immune system fights infection.
The integumentary system protects the body from outside damage.
The lymphatic system connects the lymph nodes in our bodies and helps the circulatory and immune systems.
The muscular system allows us to move.
The nervous system transmits signals through the body and controls voluntary and involuntary actions.
The reproductive system allows us to have sex and children.
The respiratory system enables us to take in oxygen and expel carbon dioxide as we breathe.
The skeletal system gives our bodies a framework and supports the systems.
The urinary system expels waste.
All of these are only some of the main functions of each system, but each system performs many others.
2. There are four blood groups: A, B, AB, and O
Your lettered blood type is determined by which antibodies are in your plasma and which antigens are found on your red blood cells. Antibodies are blood proteins, while antigens are substances that activate an immune response and control what enters and exits a cell. Each blood group can be either positive or negative, resulting in eight possible blood types. The +/- part of a person’s blood type is determined by the presence (or absence) of a third antigen called the Rh factor.
Our bodies can handle blood without the presence of an antigen that we usually have, but cannot handle the introduction of a new antigen into the circulatory system. That’s why people with O- blood are known as universal donors; anyone can use O- blood. People with AB+ blood, on the other hand, are universal recipients; they have every antigen in their blood already.
3. Our DNA is stored in 23 pairs of chromosomes within the nucleus of every cell in our body
DNA human biology
DNA has 23 pairs of chromosomes and exists in the nucleus of every cell in our body.
Each cell has a full set of chromosomes which contain all the genetic material needed to determine the makeup of our entire bodies. That’s why cloning of animals can be done with just one cell. All the genetic material that defines us is inside each and every cell of our body, from our hair follicles to toenails.
4. Our immune system fights off infection mostly through the use of antibodies and microphages
Antibodies actually fight infection by killing the virus or foreign bacteria, while microphages are white blood cells that surround and contain the foreign cells (or other objects) to prevent the spread of disease.
5. There are more non-human cells in our body than human ones
There are ten times more bacteria cells in our bodies than our own human cells. These bacteria are harmless or even help us perform key bodily functions, such as digestion. Even our DNA itself isn’t all from human evolution. Human DNA includes the genes from at least eight retroviruses that were absorbed into our own genetic code at some point. The viral genes in our DNA now perform important functions, especially related to reproduction.
6. We have more than five senses (and each has its own sensory organ or specialized receptors)
While we typically think of the traditional five senses of touch, taste, hearing, vision, and smell, our bodies can actually sense many other things. Some of the most important senses include:
Vision
Hearing
Smell
Taste
Touch
Balance
Temperature
Proprioception (spatial body awareness, aka why you can touch your nose with your eyes shut)
Pain
Each is associated with its own organ (taste with the tongue, smell with the nose) or sensory receptor (the skin contains separate touch, temperature, and pain receptors).
