Variety of animal cells

Smooth muscle cells are cells which show no variation in a tissue. They are spindle shaped which allow them to contract and relax in the muscles of the alimentary canal allowing peristalsis to take place.

All other examples show variation within a tissue. The first example is squamous epithelial cells which are more commonly known as cheek cells. Although the cells rubbed from a cheek are identical to each other, the tissue also contains columnar cells. The function of cheek cells is to protect the cheek lining. They have a flat irregular shape which allows cells to form a loose covering layer which is constantly replaced from below during wear and tear.

The columnar epithelial cells are taller than they are wide and line the cheek. They help protect the lining and produce the loose covering cells.

The next example is blood tissue. There are several types of cell. Examples include the red blood cell and the white blood cell. The red blood cell is biconcave in shape. This provides a large surface area for the uptake of oxygen. In addition there is no nucleus. This allows it to be filled with haemoglobin to pick up oxygen.

There are 2 types of white blood cells. One example is PHAGOCYTES. These have the ability to change shape and engulf micro-organisms in a process called phagocytosis. They contain lysosomes which contain powerful digestive enzymes to digest microbes.

The other type of white blood cell is lymphocyte. A lymphocyte can produce antibodies in response to the surface proteins on a virus or other microbes. The lymphocyte posses receptor proteins which allow them to do this.

Another type of tissue which shows variation is the ciliated epithelium found lining the trachea. Goblet cells are cup shaped and are able to produce mucus. This traps the dirt and germs. The ciliated epithelial cells have hair like cilia which beat upwards sweeping dirty mucus up away from the lungs.

Another example of a tissue with a variety of cells is nerve tissue. There are 3 kinds of nerve cell or neurone. The first type is the sensory neurone which carries impulses from the sense organ to the central nervous system (CNS). This has a long fibre (insulated extension of cytoplasm). This will transmit nerve impulses long distances.

The second type of neurone is a motor neurone which also has a long insulated fibre to transmit electrical impulses. It carries impulses from CNS to muscles.

The third type of neurone is a relay neurone. It transmits impulses within the CNS. It has many branches to make connections with other neurones.

Copy the following information. Some tissues have only one type of cell e.g. smooth muscle cells. Some tissues have more than one cell type. There is variation between cells of one tissue type. Variation is even greater between cells of different tissues.

What to do. 1. Collect handout sheet showing pictures of cell types. 2. Copy and complete the following table using information from the presentation and textbook chapter 1. Cell typeSpecialised Features How structure suits function

Cell typeSpecialised FeaturesHow structure suits function Smooth Muscle Squamous Epithelium ( Cheek Lining ) Columnar Epithelium ( Cheek base ) Red Blood Cells WBC Phagocytes Lymphocytes Epithelial ( Goblet cells) Nerve Cells Epithelial ( Hair cells) Spindle shaped and form sheets Lets them contract and relax to push food Flat irregular shape Lets them form a loose covering for protection Tall wide and can make squamous cells Provides a foundation on which squamous cells built and protects lower layers Small, biconcave discs = large surface area. No nucleus and filled with Haemoglobin Lets lots of O 2 diffuse in and be carried (Hb) Cup shaped and produce mucus Mucus traps dust and germs Cilia on outer membrane Cilia move mucus to back of the throat Long insulated fibres Carry electrical impulses Can change shape and have lysosomes with digestive enzymes Engulf and destroy microbes Produce antibodies and have receptors on membrane Detect and inactivate microbes