Cells
A cell is a microscopic functional unit of a living thing, they are like our “structure”.
There are many different types of cells:
- Plant, animal, neurons, red blood, female´s reproductive cell and male's reproductive cell.
Humans are made of a lot of cells, because there cannot be a cell that can complete all the tasks there must be made.
The Cells and their functions
- Plant cells: These cells have a uniform structure, and contains all of the parts that a cell can contain. These cells can make tissues, which form some organs and systems in our body.
- Animal cells: Animal cells contain only the half of the required parts (cell membrane, cytoplasm and nucleus), they also have a ‘weird’ shape, they’re irregular. These cells can also form tissues, like plant cells.
- Red Blood cells: This cell is not as complex as plant or animal cells, this cell has this special job: Carry oxygen to our entire body when it needs it. They contain haemoglobin (protein in red blood cells) which combines with oxygen. As its name states, red blood cells travel through blood. For example, when we exercise our muscles require extra oxygen, there's where red blood cells act.
- Nerve Cells: Also called neurons, play a very important job, which is carrying nerve impulses into different parts of the body; they are the ones in charge of the sense of touch and taste. When we touch something, this cells immediately send a message to each other so the brain can react in time.
- Female´s reproductive cell: Also called ovum (or the egg), have this peculiar job that requires another cell. This job is all about reproduction. The ovum is holded in the ovary during 14 days, until it matures, then it has travel through fallopian tube until sperm shows up (male's reproductive cell), if any sperm arrives, then, the ovum disintegrates, but if a sperm DOES show up then it's another story...
- Male's reproductive cell: Also called spermatozoa, have a mission to complete. This mission consists in finishing this specific race to win the most significant trophy: life. This sperms travel all the way thru a male's testicles (semen) to a woman's uterus (this trip lasts 1 hour) when a couple has sexual relationships, when a sperm enters to the ovum they drop their tale, ovum closes so that no other sperm can enter, the other millions die. When the sperm enters the ovum there´s a fusion that unites both woman and male´s cell, that is called fertilization. Nine months later a baby is born.
Cells parts
So cells can functionate they need a certain kind of parts, each part have an important role in the cell:
- Cell membrane: It controls the substances that get in and out of a cell.
- Nucleus: This is the part that controls what happens inside the cell, it carries genetic data.
- Cytoplasm: Its a jelly-like substance, where the chemical reactions happen.
(ONLY PLANT CELLS)
- Chloroplast: It's in charge of the photosynthesis, it contains a green substance called chlorophyll (what gives plants and some vegetables green pigment)
- Vacuole: An organelle that “allows” the cell to “store” substances like water or salt.
- Cell wall: Its a resistant wall that supports the cell, made of a substance called cellulose (chemical compound), which is a very important substance for the cell wall.
How do cells make tissues, organs and systems?
Animal and plant cells have also a very specific and basic jobs: making tissues. A tissue is made by a specific group of cells that have a similar structure, which all work together to form tissues. Some examples of tissues are:
- Muscles
- Lining of lounges
- Lining of the intestine
- Root hair tissue (for plants to pick up minerals from soil)
- Phloem (Tubes that carry dissolved sugar around the plant)
Tissues have this important job that helps living things to survive: Making organs, which help plants and animals to live with their needed conditions. Here are some examples:
- Brain
- Heart
- Lung
- Stomach
- Leaf
- Root
A organ system is made of different organs, these organs help us to accomplish a job. Here are some examples:
- digestive system
- nervous system
- reproductive system
- respiratory system
- circulatory system
- urinary system
- Leaf canopy
