Learn about the different tissues that are found in humans and plants. This lesson summarizes the four tissue types in humans and the three tissue systems of plants.
Examination of Tissues
A tissue is one of the building blocks of an organism–either animal or plant.
An organism is comprised of tissues, which are made up of individual cells. These cells share a similar structure (how they’re built) and function (what they do). The study of tissues is a field known as histology.You may be asking why tissues are important. . . it’s simple! Tissues are what makes up our bodies: everything from our bones to organs like our heart and brain! Even blood is considered to be a tissue!
The Four Basic Human Tissue Types
In humans, there are four basic tissue types, which are: epithelial tissue, connective tissue, muscle tissue and nervous tissue.
Within each general tissue type, there are specific tissue types. Think of this like a football team. There are individual players, each with their own ‘job’ on the field.
These are the specific tissue types. The football players are then categorized into either an offense or a defensive team. These teams would be the basic tissue types. The offense and defensive teams are combined into one football team, or an organism.
Epithelial and Connective Tissue
The easiest way to describe an epithelial tissue is to say that it covers something; typically an organ. The skin of our bodies is just one big piece of epithelial tissue!All epithelial tissues share one thing in common: a basement membrane.
A membrane is a very thin layer of tissue. It’s so thin that you can typically see through it! So, how is a basement membrane different from a ‘regular’ membrane? Where in your house do you find the basement? The very bottom level of your house, right? A basement membrane is exactly that: the very bottom layer of a tissue.Different types of epithelial tissues are defined by two things:
- The cell shape they have
- How many cell layers thick they are
Epithelial tissues have one of three main cell shapes: columnar, cuboidal, and squamous. Columnar cells look like columns, and cuboidal cells look like cubes. Squamous cells are scale-like.The number of cell layers each epithelial tissue has falls into one of two categories: simple, which means 1-cell layer thick, or stratified, which means more than 1-cell layer thick.Specific epithelial tissue types consist of the combination of the cell shape and number of cell layers.
For example, simple cuboidal epithelial tissue describes tissue that is one cell layer thick, with cells that are cube-like in appearance. This tissue, in part, is what makes up our kidneys!
Connective tissue does just that–it connects things in our body together! This tissue has many different specific types, which range from bone and cartilage, which make up the human skeleton, to blood and fat (also known as adipose connective tissue).
Muscle and Nervous Tissue
There are three different types of muscle tissue. They are smooth, skeletal and cardiac muscle tissue.
Smooth muscle and cardiac muscle are under involuntary control. This means, we can’t tell these muscles to work. This comes in handy considering where these tissues are found – smooth muscle makes up the organs of our digestive tract, our stomach and intestines, and cardiac muscle is found in our heart. Can you imagine having to ‘tell’ your stomach to digest your food or your heart to beat?Skeletal muscle, on the other hand, is under voluntary control, which means we need to tell our muscles to work.
The epidermis in plants are the cells that combine to make up the leaves. Have you ever heard of the epidermis in humans? It’s another word for our skin. The vascular tissues transport water and food to the plant from the roots and the leaves. Ground tissue makes nutrients for the plant using a process called photosynthesis, which means using sunlight to make energy.
Humans have four basic tissue types, which are epithelial, connective, muscle and nervous.
Within each of these broad categories, there are specific tissue types. Specific epithelial tissues are characterized by their cell shape and how many cell layers thick they are. There are many different specific connective tissues, but the one thing they have in common is that they connect things in our body. There are three different muscle tissues, skeletal, smooth and cardiac.
However, there is only one type of nervous tissue.Plant tissues are a bit different. Instead of tissue types, plants have tissue systems that are classified by the job they do.
The three tissue systems are the epidermis (or ‘skin’ of the plant), the vascular, which transports water and nutrients in the plant, and the ground tissue, which makes nutrients for the plant.
Types of Tissues
|*Epithelial: columnar, cuboidal, squamous *Connective: includes bone, cartilage, blood and fat *Muscle: skeletal, smooth and cardiac*Nervous||*Epidermis *Vascular *Ground Tissue|
When you are done, you should be able to:
- Name and describe the four basic types of human tissue
- List the different types of epithelial, connective, and muscle tissues
- Describe the three plant tissue systems