Types of Cells

Review

• Watch the following video• How Stuff Works - Cells video

Multi-cellular Organisms

• Living things can be as simple as single-celled organisms such as a Paramecium or an Amoebathat lives in pond water or as complex as multi-celled organisms such as humans.

• The cells in a multi-celled organism are specialized so that they can perform specific functions for the organism.

• Larger organisms contain more cells and require more complex methods to carry out their life processes.

• Paramecium

• Amoeba

• Red blood cells are one type of cell found in the human body. Mature red blood cells no longer have a nucleus so they do not have the ability to divide.

Cell Specialization

• Although we begin as a single fertilized cell, we contain many different cells such as:– Blood cells– Skin cells– Bone cells– Muscle cells– Nerve cells

• The process by which cells become specialized is called differentiation.

• Cells that are specialized will possess unique structures and functions.

• Cell differentiation leads to a multi-cellular organism with a greater efficiency for performing different tasks.

Skeletal Muscle Cells• They have a long and fibre-like appearance. • They also contain a high concentration of

mitochondria. • These characteristics allow the cells to contract

and stretch during the movement of the muscles.

Nerve Cells• Also known as neurons, are long, fibre-like cells

with one long extension called an axon and branching extensions called dendrites.

• These structures help to conduct nerve impulses throughout the body of an organism.

1. Why is it important that our cells differentiate?

2. a) List some of the different types of cells found in the human body. b) Describe the structure and function of one of those types of cells.

Write the following question into your notebook and then check your answer when you are finished your work.

Levels of Biological Organization

• The levels of biological organization begin with the simplest level, the cell, and end with the most complex level, the organism.

• Cells: are the basic structural units of life. • Tissues: A group of specialized cells that have

the same structure and perform the same function, such as bone tissue.– Example: Blood is a tissue, where different kinds of

blood cells are grouped together to transport oxygen, nutrients, wastes, and other materials throughout the body.

• Organs: A structure composed of different tissues specialized to carry out a specific function.– Example: The heart is an organ made up of many

tissues. For example, the muscle tissue in the heart is responsible for pumping the blood throughout the body and the nervous tissue coordinates the muscular activity of the heart.

• The heart is an organ made up of many different types of tissues working together to pump blood throughout the human body.

Organ System

• Definition: A group of organs that have related functions.

• Example: The digestive system is made up of several organs that perform specific functions to ensure that food is broken down, called digestion, so that it can be used by the cells.

Some of the organs of the digestive system

• Some other organ systems are: – The circulatory system– The respiratory system– The nervous system

• Each organ system has a specific job in maintaining homeostasis (constant internal conditions) within the organism.

• When one of the organs in an organ system fails to function properly it will affect the entire system.

• This could lead to serious consequences on the performance of the organism and may even be the cause of death.

• Example: A heart attack may damage or destroy a section of the heart and impair the functioning of this organ, which in turn affects the entire organism because the heart can no longer work to pump blood around the body.

3. The levels of biological organization from simplest level to most complex level are: a) , b) , c) , d) , e) .

4. a) Name three organ systems. b) Will the organ system continue to function if

one of the organs is not working properly? Explain.

Write the following question into your notebook and then check your answer when you are finished your work.

Questions and answers

1. Why is it important that our cells differentiate?

It is important that our cells differentiate because we are large, multi-cellular organisms with complex processes. We require specialized cells to carry out all of the functions needed for our body to survive. Differentiation of cells leads to greater efficiency for performing tasks.

2. a) List some of the different types of cells found in the human body. b) Describe the structure and function of one of those types of cells.

a. nerve, muscle, bone, skin, and blood cells b. Nerve cells are made up of a long axon and

branching extensions called dendrites which function to send impulses throughout the body.

3. The levels of biological organization from simplest level to most complex level are: a) , b) , c) , d) , e) .

a) Cell b) tissue c) organ d) organ system e) organism

4. a) Name three organ systems. b) Will the organ system continue to function if one of the organs is not working properly? Explain.

a. Three organ systems are the digestive system, respiratory system, and circulatory system.

b. The organ system will not continue efficiently if one of the organs is not functioning properly. Each organ is dependent on the other to carry out the overall task of the system. The effect of one organ not working properly may be very drastic to the organism. e.g., an inefficient heart with not allow oxygen, nutrients, carbon dioxide, wastes, and other materials to move to and from the heart effectively.