Index
They are any cell in the body that are not gametes (sperm or ovum), germ cells (cells that become gametes) or stem cells.
Essentially, all cells that make up the organism of a living being and are not used to directly form a new organism during reproduction are somatic cells.
The word somatic comes from the Greek word σὠμα (soma), which means body. In the human body, there are about 220 types of somatic cells.
Examples of somatic cells
There are many different types of somatic cells in the human body because almost all the cells that are found inside and on the surface of the human body, with the exception of cells that turn into sperm and eggs, is a somatic cell.
In addition, mammals have many organ systems that specialize in specific functions, so there are many different specialized cells.
The following is a general description of some major types of cells in the human body:
Bone cells:
The old bone cells are constantly replaced with new bone cells. The two broad categories of bone cells are called osteoblasts and osteoclasts. Osteoblasts form bone and help maintain it. They are cubic or square, and form proteins that form bone.
They also communicate with each other and produce certain molecules, such as growth factors, that promote bone growth.
Osteoclasts, on the other hand, reabsorb or dissolve the old bone. They are large cells that have multiple nuclei. When the work of an osteoblast or osteoclast is performed, it is subjected to a programmed cell death known as apoptosis.
Muscle cells:
Muscle cells are also known as myocytes. They are long, tube-like cells. There are three types of muscles each composed of specialized myocytes: smooth muscle, cardiac muscle and skeletal muscle.
Smooth muscle fills the walls of internal organs, such as the bladder, uterus, and digestive tract. The heart muscle is only found in the heart and allows the heart to pump blood. Skeletal muscle is attached to the bone and helps move the body.
The various parts of myocytes have a special terminology because myocytes are very different from other cell types. The cell membrane is called sarcolemma , the mitochondria are called sarcosomes and the cytoplasm is called sarcoplasma.
The sarcomere is the part of the cell that contracts and allows muscle movement, forming long chains called myofibrils that run through each muscle fiber.
Muscle cells can not be divided to form new cells. This means that although muscles can get bigger with exercise, babies actually have more myocytes than adults.
Nerve cells:
The nerve cells are called neurons. Neurons are found throughout the body, but there is an especially high density in the brain and spinal cord, which controls the movements of the body. Neurons send and receive information to and from other neurons and organs through chemical and electrical signaling.
Neurons maintain a certain voltage, and when this voltage changes, it creates an electrochemical signal called action potential.
When an action potential occurs in a neuron, the neuron will release neurotransmitters , which are chemicals that affect the target cells. Some examples of neurotransmitters are dopamine, serotonin, epinephrine (adrenaline) and histamine.
Annotated neuron:
The neurons have a unique structure as shown in the diagram above. The main parts of a neuron are the soma, the axon and the dendrites. The soma is the body of the cell and contains the nucleus.
The axon is a long protrusion that transmits electrical impulses. The dendrites fan out from the soma and receive impulses from other neurons. The end of the axon branches off at the axon terminals, which is where the neurotransmitters are released.
Blood cells:
Blood cells are called hematopoietic cells or hemocytes. There are three general types of blood cells: red blood cells, known as erythrocytes, white blood cells or leukocytes, and platelets, also known as thrombocytes or red blood cells.
These cells, together with the plasma, comprise the content of the blood.
The erythrocytes transport oxygen to the cells through the hemoglobin molecule and collect the waste product carbon dioxide from the cells. They make up 40 to 45 percent of the blood volume. Approximately one quarter of the cells in the human body are erythrocytes.
They live between 100 and 120 days, and they have no nucleus when they are mature. Leukocytes defend the body against foreign substances and infectious agents such as viruses and bacteria.
They have a very short lifespan of only three or four days. Platelets are fragments of small cells that help blood to clot after an injury. They also have a short lifespan, living for five to nine days.
Differences between somatic cells and gametes
Somatic cells are produced through the process of cell division of mitosis . They contain two copies of each chromosome, one from the mother of an organism and one from her father. Cells with two copies of each chromosome are called diploids.
Sperm and ovum, called gametes, are formed through meiosis, which is a slightly different cell division process that results in cells having only one copy of each chromosome.
These cells are called haploids. Gametes are haploid because a sperm and an egg merge during fertilization to create a new organism with diploid cells.
Mutations in somatic cells can affect an individual organism, but do not affect the offspring since they are not transmitted during reproduction. However, the mutations that occur in the gametes can affect the offspring since the gametes are transmitted.
When the gametes fuse, they become the first somatic cell of the offspring, which later divides to form all their other somatic cells.
Therefore, although mutations in somatic cells will not affect the next generation, mutations in gamete cells do have and can sometimes have drastic effects.
For example, if a large-scale mutation occurs and there is an extra chromosome in the fertilized egg, all somatic cells will also have that extra chromosome when it is split. An additional chromosome 21 results in Down Syndrome .
