Exercise 1.1 Levels of Organization

The human body is a composite of very complex structures and

systems. It is also very organized, from the organ system to the

cell. The human body is an organism. You are an organism. In this

exercise you will learn about the different levels of organization in

the human body and the functions of each.

Objectives:

Be able to identify the different levels of organiza-

tion in the human body.

Be able to list the functions of each organizational

level of the human body.

Know the 4 classes of tissues, their functions, and

where they may be found in the human body.

Describe the various organ systems and list organs

within each system.

Cells are the smallest units of life

The human body contains about 200 types of cells and over a

trillion cells altogether. The cells in the body differ majorly in

their function and some their structure. Below is a diagram of

different types of cells in the human body.

When 2 or more cells come together to perform a specific

function, they are now known as a tissue.

Cells make Tissues

We know that cells come together to make tissues. A tissue is a

group of similar cells with a specific function. There are four

classes of tissues. Each one has a specific function and specific

features to look for. The study of tissues is called histology.

4 types of tissues

Epithelial

Connective

Muscle

Nervous

Epithelial tissues can be difficult to differentiate so we classify

and name them by their shape and how many layers that they ap-

pear in. The functions of epithelial tissue include: cover and pro-

tects exposed surfaces, lines internal passageways and chambers,

and it produces glandular secretions. Below is a chart that de-

scribes the way that epithelial tissue is classified.

Older Cells

Newer Cells

Connective tissues function in support. All connective tissues con-

tain cells and an extracellular matrix. The extracellular matrix is

made up of protein fibers and a liquid ground substance. Connective

tissues function in filling internal spaces, providing structural sup-

port, and storing energy. There are many different types of con-

nective tissue but all are easily identified. Below is a generalized

diagram of a connective tissue.

Here are a few examples of types of connective tissue:

Bone

Blood

Cartilage

Muscle tissue is an unique tissue because its cells have the ability

to contract and relax. This contraction and relaxation produces

movement in the body. There are three types of muscle tissue and

are listed below.

Cardiac Muscle

Striated (striped appearance)

Intercalated Discs

Usually 2 nuclei per cell

Involuntary (unconscious)

Located in the heart

Skeletal Muscle

Striated (striped appearance)

Multinucleated

Voluntary (conscious)

Found attached to the skeleton

Smooth Muscle

Non-striated

1 nucleus per cell

involuntary (unconscious)

Located in walls of blood

vessels and within glands.

Nervous tissue is a specialized type of tissue that carries informa-

tion from one place in the body to another. There are two basic

types of cells in nervous tissue: nerve cells (neurons) and supporting

cells (neuroglia). Neuroglia support and protect the neurons in the

central nervous system and the peripheral nervous system.

Neurons

Neuroglia

Directions: Answer the following questions about tissues.

1. Name the four tissue classes.

A. __________________

B. __________________

C. __________________

D. __________________

2. Name two locations where epithelial tissue may be found. (try to

use examples other than those given in the exercise)

A. __________________

B. __________________

3. Name a function of connective tissue and give the components of

the matrix in connective tissue.

A. __________________

B. Matrix components:

I. __________________

II. _________________

III. ________________

4. What are the three muscle tissue categories? Which are volun-

tary and which are involuntary? Which are striated and which are

not?

Category Vol./Inv. Striated?

A. __________________ ______ ______

B. __________________ ______ ______

C. __________________ ______ ______

5. What is the difference between a neuron and a neuralgia cell?

__________________________________________________

__________________________________________________

__________________________________________________

__________________________________________________

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Tissues Concept Map Answer Sheet

1. ______________________

2.______________________

3.______________________

4.______________________

5.______________________

6.______________________

7.______________________

8.______________________

9.______________________

10.______________________

11.______________________

12.______________________

13.______________________

14.______________________

Tissues make Organs and Organs make Organ systems

An organ is a functional unit composed of at least 2 different types

of tissues. An organ system is comprised of two or more organs

working together for a function. Below is an example of organs

coming together to make an organ system.

The Digestive System

Below is a table showing all of the major body systems in the human

body along with their functions. Keep in mind that although they

are separated in this table, the body systems work together in the

body to help keep you alive.