GRADE: Seventh

CONTENT STANDARD: Life Science

CONTENT TOPIC: Diversity And Adaptations Of Organisms

CONCEPT: Animals are classified according to various structures.

CONTENT OBJECTIVE: 7H4.00 To understand the development of animals and their body systems

INSTRUCTIONAL OBJECTIVES: The learner will:

4.01 define behavior and types of behavior for animals.
4.02 describe and demonstrate the functions of an animals' skeleton.
4.03 explain the differences and advantages of the endoskeleton and exoskeleton.
4.04 compare the digestive systems in animals ranging from primitive to highly advanced.
4.05 describe the process of respiration concerning skin, gills, and lungs.
4.06 explain how circulation occurs.
4.07 draw the various types of hearts found in animals.
4.08 describe the main functions of a nervous system.

I. Support systems in animals
II. Digestive systems in animals
III. Respiration
A. Moist skin
B. Gills
C. Lungs
IV. Circulation - types of hearts
V. Nervous systems
A. Brain or nerve centers
B. Nerve cells
C. Subsystems in nervous system of advanced animals

TN COMPONENT OF SCIENCE: Process of Science

TN GOAL:

To enable students to demonstrate the processes of science by posing questions and investigating phenomena through language, methods and instruments of science.

COMMUNICATING - An essential aspect of science is the act of accurately and effectively conveying oral, written, graphic or electronic information from the preparer to the user.

1.6a The sharing and disseminating of results should be done in a clear and concise manner.

BENCHMARK: Human beings learn complicated concepts from others through various methods of communication.

TIME REQUIRED:

One week of instructional periods

Overhead drawings, examples of various bones and insects (roach, beetle, grasshopper.) Teacher made overheads of systems discussed

Alveoli, antennae, bronchial tubes, cartilage, closed circulation, diffusion, digestive enzymes, digestive glands, endoskeleton, exhale, exoskeleton, joints, liver, lungs, nerves, pancreas, respiration, secrete, sense organs, spiracles, stimulus, systems, trachea, tympanic membrane

We will be studying the body features or systems of several animals. We will use as examples, several animals. These animals will vary from the very simple earthworm to the very complex frog.

Behavior is a what an organism does. The behavior will be triggered by a stimulus. The way an animal reacts to a stimulus is called it's response. (Activity - teacher drops an empty metal trash can or other loud object in the back of the room. After the students react, re-define the stimulus and their response.) Most animals need a means of support and movement to seek food and survive in their environments. A few animals, such as the earthworm and the jellyfish, depend on their environment for much of the body support. These examples are exceptions because, as a rule, land and water animals have systems that are "built-in" for support and movement.

Some animals have their skeletons located on the outside - an exoskeleton. It is a very hard, strong body covering that protects the soft body parts underneath. The animals with exoskeletons that exist today have been very successful survivors due to their skeletons. For example, cockroaches and beetles date back to the earliest known fossils and art forms.

The endoskeleton is where the skeleton is located inside the animal's body. It is made of cartilage and bone tissue. The skeleton consists of many bones. Where these bones meet are called joints. Joints allow the skeleton to work with the muscular system to cause movement. Bend your elbow and scratch your nose. Could you do this without the elbow joint? (response) We are now going to draw and label the main bones of your own skeletal system.

We have already learned that living organisms must have energy to live. For animals who must seek their food, the digestion of food is necessary to release energy from food. The lower phyla of animals have very primitive systems for digestion. The earthworm has a system for digestion involving one long tube from mouth to anus. This tube must do the grinding of food, the production of digestive enzymes, the break down of food and the elimination of waste. (Show overhead or other drawings of earthworm's digestive tube.)

The grasshopper shows a more advanced digestive system. Here we are able to see an organ outside the digestive tube that is contributing to the process. The digestive glands are located outside the stomach.

They make and secrete digestive enzymes into the stomach. The addition of "helping organs" outside the food tube is extensive in the higher forms of animals. We see this same situation in the frog. Enlargements and variations within the tube itself also enhance the digestive process.

Attached to the frog's food tube are organs such as the large liver to store food and the pancreas to release digestive enzymes. Other enzyme producers are the gall bladder and spleen.

Respiration in animals involves a system known as the respiratory system. The process involves the intake of oxygen to be used and the output of carbon dioxide to eliminate as waste.

The earthworm does not have an actual respiratory system. Air diffuses through it's moist skin and is taken into the blood cells. The earthworm lives underground tunneling air spaces through the soil. The underground environment keeps the skin moist (avoid air and heat) and allows air to enter the skin.

The grasshopper has a series of air holes in it's exoskeleton. Through the body movement of the grasshopper, air flows into these holes, called spiracles. The air flows through tubes connecting spiracles to air sacs. Blood flows over and through the air sacs to pick up O₂.

The frog has a very advanced type of respiratory system. The flow of air is as follows:

1. Air enters nostrils

2. Flows down trachea

3. Trachea branches into two tubes called bronchial tubes

4. Each bronchial tube enters into one of the two lungs

5. The air sacs filling the lungs are called alveoli. Each alveoli has numerous capillaries that diffuse out the O₂ and release CO₂ into the alveoli. This CO₂ leaves the frog's body as it exhales.

The circulatory systems of animals show as much diversity as seen in the respiratory systems. The purpose of circulation in animals is to move food, O₂ and waste through the body. The requirements for circulation are: 1) a pumping station (usually a heart) 2) tubes (usually blood vessels) and 3) a liquid (usually blood).

Insects, such as the grasshopper, have a series of pumping chambers. These are not consolidated into one organ. The more advanced the animal, the more advanced the heart. For example, fish have two chambers to the heart, frogs have three chambers and birds and humans have the four chambered heart.

In the animals with the heart as an organ, the circulation is called closed circulation. This means that blood does not leave the system. If blood is leaking from the system the organism is said to be bleeding.

The tubes travel away from the heart, reach body parts, and return to the heart. This is why the system is called circulatory, the blood flows in a "circle" around the body. Body cells are able to take in and eliminate substances through the thin walls of the tubes. The exchange of material between vessels and cells is by diffusion.

Body control involves a system known as the nervous system. This system is seen in very simple organisms in things such as eye spots and nerve hairs. These simple cells are able to pick up stimuli from the environment and cause reactions within the organism.

In higher forms of animals these nerve cells are organized into systems. The nerve center will control or determine an animals response. The nerves connect the animal's body parts to the nerve center. Sense organs are designed to pick up stimuli from the environment and relay these messages to the nerve center. Here an appropriate response can be determined.

The earthworm has a very small brain in the head. A nerve cord runs through the worm. The main sense organ of the earthworm is in the skin.

The grasshopper has several sense organs such as eyes, antennae and tympanic membranes to pick up sound waves.

The most advanced animals will have a brain and spinal cord with many nerves running from these two organs to all body parts. Sense organs are designed to be selective, picking up only one type of stimulus. For example, eyes pick up light but do not detect sound waves or smell.

An animal is very dependent on the nervous system, whether simple or complex, to interpret and react to it's environment.

(The following activities are suggestions to be used with the lessons.

1. Select a large insect such as a beetle or roach and a bone from an animal such as a chicken or cow. Compare the structure of the exoskeleton with the endoskeleton.

2. Select earthworm or grasshopper and obtain a dissecting microscope. Examine the outside structures of these animals under the microscope.

3. From an overhead of the human skeletal system draw and label the major bones of the human skeleton. Have each student locate these bones on his own body. (Also, teacher can label a model skeleton if one is available.)

4. Obtain a heart of a cow or pig from a meat packing company to dissect in class.

We have been learning about the different systems found in animals. We have seen each of these systems in a simple form in simple organisms. As the type of animal developed and progressed we saw the systems do the same.

1. What is your response when you hear the stimulus of a telephone ringing? the bell for lunch? smell from a bakery? (Answers will vary.)

2. How would your life be different if you had no joints in your skeleton? (Answers will vary.)

3. Why would a frog need to store food in its large liver? (It hibernates during winter.)

4. Why do earthworms come to the surface of the ground after a heavy rain? (The air passages they tunnel and travel in fill with water which could drown them.)

5. How would bug spray or bug dust, such as Sevin, affect spiracles? (These spiracles allow the poison to enter the insects body.)

6. Name another system in nature that shows circulation not found in the body of an organism. (Water cycle, oxygen-carbon dioxide cycle, energy cycle . . .)

7. What are your sense organs? (Nose, taste buds, ears, skin, eyes.)

alveoli - tiny air sacs in the lungs that are filled with capillaries.

antennae - sense organs that can detect taste, heat and odors.

bronchial tubes - where trachea divides into two branches, one to each lung.

cartilage - elastic skeletal tissue that will "give" under pressure.

closed circulation - where the blood is always enclosed in the system, does not leave the heart and blood vessels.

diffusion - particles move from an area of high concentration to an area of less concentration.

digestive enzymes - enzymes produced by an organism to speed up the process of digestion.

digestive glands - glands that secrete digestive enzymes.

endoskeleton - the skeleton is located internally in the animal.

exhale - to release CO₂ from the lungs.

exoskeleton - skeleton located on the outside of an animals body.

joints - where two bones come together or meet.

liver - organ of the digestive system that produces bile and stores glycogen.

lungs - organs filled with alveoli where gases are exchanged with the blood.

nerves - strands of nerve cells

pancreas - digestive organ that produces digestive enzymes and insulin.

respiration - the intake of oxygen and release of carbon dioxide.

secrete - to release.

spiracles - tiny holes in the sides of an insect's body to allow air to enter the body.

stimulus - anything that causes a response.

systems - groups of organs working together to do a job.

trachea - tube from mouth into the chest cavity.

sense organs - organs that pick up a certain stimulus from the environment.

tympanic membrane - organ that picks up sound waves (found on outside of the bodies of insects and frogs).

This is the time this file has been accessed since 04/02/98.

The University of Tennessee at Martin is not responsible for the information or views expressed here.

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