Do Dissections Make You Queasy? I’ve Got You Covered

Dissections are a traditional component of most advanced biology courses beginning at the high school level. Dissections provide a way for students to learn about the internal and external anatomical structures of animals. By taking a hands-on learning approach, students can get a real sense of the relationships between organismal structures.

dissectionsFor many students however, dissections can be very disturbing. Online dissections provide an opportunity to experience animal dissections in a unique manner without all of the mess. Some online dissections provide visual images along with step-by-step instructions on how to dissect a particular animal. Others provide diagrams and pictures that display certain anatomical structures.

The good news is that there are many amazing virtual dissections available for free online. From earthworms to human cadavers, the web has remarkable learning options available at the click of a mouse.

Note: These images are often understandably graphic and may be upsetting to some kids. You may want to preview these sites to see which ones are best suited for your children.

Online Dissection Links

Mammals

Birds

Fish

Invertebrates

 

 

STEM Club: The Circulatory System

The Circulatory System consists of the heart, blood vessels, and the approximately 5 liters of blood that the blood vessels transport. Responsible for transporting oxygen, nutrients, hormones, and cellular waste products throughout the body, the cardiovascular system is powered by the body’s hardest-working organ — the heart, which is only about the size of a closed fist. Even at rest, the average heart easily pumps over 5 liters of blood throughout the body every minute.

circulatorysystem

 

The Heart

The heart, blood, and blood vessels are responsible for distributing the life-giving substances – oxygen and nutrients – throughout the body. Circulation begins with the heart. The heart is a large muscle that squeezes itself about once every second, sending blood flowing throughout the body’s network of blood vessels.

diagramheartThe hollow, muscular heart organ is divided into two sides or pumps. The left side sends blood to the aorta (the large blood vessel that leaves the heart) and through arteries, smaller arterioles, and capillaries (the smallest blood vessels in the body) to all the cells in the body. This blood transports oxygen to the cells and picks up carbon dioxide in return.

On the return trip, the blood travels in smaller veins (blood vessels that carry blood back to the heart) that connect to larger veins and eventually to the vena cava, the large vein that leads to the right side of the heart. The right side of the heart pumps the blood up to the lungs (via the pulmonary vein), where it takes in a new supply of oxygen and releases carbon dioxide. The blood then makes a quick trip back to the left side of the heart and the cycle begins again.

You hear two sounds during every heartbeat that goes something like this:     lub-DUB        lub-DUB        lub-DUB

Lub is the sound of the tricuspid and mitral heart valves shutting (on the top chambers). Then a pause as the top chambers relax. Dub is the sound of the semilunar heart valves closing. These valves shut off the big vessels leaving the heart. Then a longer pause.

The left side of the heart muscle is a bigger and stronger pump because it must push blood through the entire body. It takes about 23 seconds for the heart to circulate blood through the body.

In STEM Club, I first had the kids sketch a diagram of a heart in their notebooks and trace the route of blood flow through each chamber. When this was complete, we moved to the kitchen.

I had purchased a cow heart from a local butcher and intended to observe each of the heart chambers with my students. My goal was to identify the aorta, vena cava, left and right atriums, and left and right ventricles and thereby visualize the flow of blood through each.

We were able to do this to some extent, but weren’t completely successful because it was not whole. It had been cut in several places and it was difficult to discern one chamber from another as a result.

How Does Exercise Affect Your Pulse? – Group Inquiry Lab

When you feel your pulse, you are feeling blood as it is forced through an artery by the beating of your heart. Arteries are blood vessels that carry blood away from the heart. This pulse is the rate at which your heart beats.

Since the physical condition of an individual affects his heartbeat, pulse tests can be used to measure physical fitness.

Materials

  • Stopwatch
  • Data chart or notebook with the following columns:  Student Name / Inactive Pulse / Active Pulse / Recovery Pulse

Procedure

  1. Guess how many times your heart beats in one minute ( _____ bpm) and record this in your notebook.
  2. Take your pulse and record it in the inactive column as _____ bpm.
  3. Record another’s pulse. If you are doing this in a co-op or small group setting, gather the results from everyone for a larger data set.
  4. Run in place or do jumping jacks for two – three minutes.
  5. Take your pulse and record it in the active column as _____ bpm.
  6. Rest for 5 minutes.
  7. Take your pulse and record it in the recovery column as _____ bpm.

Discussion

  1. Have your pulses returned to normal?
  2. Compare your recovery rate to that of your peers.

Observing Blood

The average person’s body contains about 5 liters of blood. Blood is a tissue containing plasma, red and white blood cells, and cells called platelets. Fifty-five percent of blood is plasma which is ninety percent water, nutrients, oxygen and minerals. Forty-four percent of blood is made up of red blood cells. White blood cells and platelets make up about one percent.
diagramblood

  • Red Blood Cells are the disc-shaped cells in the plasma that carry oxygen. They are concave on both sides and do not have a nucleus. There are about 5 million in one cubic millimeter of blood. They get their color from an iron-containing protein called hemoglobin, which carries oxygen to the tissues. Red blood cells are made in the marrow of certain bones.
  • White Blood Cells fight infection. They are produced in bone marrow, lymph nodes, and in the spleen. They have a nucleus. There are about 7 thousand white blood cells per cubic millimeter of blood. There are about 7oo red blood cells for every one white blood cell. They fight infection by surrounding and engulfing the microbes that cause infection. Pus is composed largely of dead white blood cells.
  • Platelets stick to the walls of injured blood vessels and start the process of blood clotting.  This helps prevents blood from escaping. They release a chemical substance whenever there is an injury. This substance (along with other chemicals in the blood) form a mass of fibers that form the clot. Made in the marrow of bone, there are approximately 300,000 platelets per cubic millimeter of blood.

Materials

  • Prepared slides
  • Microscope with a minimum of 100x
  • Alternatively, you may use images found online

Procedure

  1. Observe the prepared slides under a microscope and make a drawing of each type of blood cell.
  2. Create a data table in your notebook with the following columns:  Blood Cell Type / Description / Number of Cells in Field of View
  3. Record your observations.
  4. Include a sketch of each blood cell type.

Discussion

  1. Which type of blood cell represents the largest number? [red cells]
  2. Describe the red blood cells. [disk-shaped, pink]
  3. What is the shape and color of the white blood cells? [shape of cell depends upon the shape of nucleus, which stains blue]
  4. Describe the different shapes of the stand nuclei in the white blood cells. [round, kidney-shaped, horseshoe-shaped, etc.]
  5. What are the solid parts of human blood? [red cells, white cells, platelets]
  6. Why are the centers of human red blood cells light in color? [there are no nuclei]
  7. How do red and white blood cells differ? [white blood cells are larger, have nuclei, are irregular shape, and are fewer in number than red blood cells]
  8. What do platelets do? [help clot the blood]

Bring it Home

  • Sketch the heart muscle in your notebook and label the major parts.
  • Design a test to show how your pulse rate varies with different exercise.
  • Write a story from the perspective of a blood cell as it journeys throughout the body.
  • Research the different blood types: A, B, AB, and O. Write a report detailing what you learned and include the following terms: antigens, antibody, and transfusion.
  • Donate blood at your local American Red Cross
  • Observe the veins, arteries, and capillaries on the underside of your tongue and below your eye. [thick blue lines = veins, thick pink lines = arteries, and thin lines = capillaries]
  • Design an test to determine whether a person’s body temperature remains constant all day.
  • Enjoy these Brain Pop videos:

STEM Club: The Respiratory System

The cells of the human body require a constant stream of oxygen to stay alive. The respiratory system provides oxygen to the body’s cells while removing carbon dioxide. 

There are 3 major parts of the respiratory system: the airway, the lungs, and the muscles of respiration. The airway, which includes the nose, mouth, pharynx, larynx, trachea, bronchi, and bronchioles, carries air between the lungs and the body’s exterior.

The lungs act as the functional units of the respiratory system by passing oxygen into the body and carbon dioxide out of the body. Finally, the muscles of respiration, including the diaphragm and intercostal muscles, work together to act as a pump, pushing air into and out of the lungs during breathing.

bromoblue

Exhaling Carbon Dioxide (demonstration)

I gave each of the students a cup of water to which I added a few drops of bromothymol blue (a chemical that is often used to test water in fish tanks and can thereby be purchased at pet stores).  I then gave each student a straw and instructed them to blow bubbles into the water, being careful not to invest or inhale through the straw. Within a few minutes, the water began to change color – eventually turning a faint yellow color.

Note: We used filtered water from our refrigerator but the lab instructions called for distilled. A fun inquiry project would be to test if the color varies with different types of water.

Bromothymol blue is an  acid indicator and will thereby turn blue in a basic or neutral solution and green or yellow-green in an acidic solution. The water was thereby light blue in appearance. When carbon dioxide mixes with water, it forms a weak acid called carbonic acid. This acid turns the bromothymol blue a green or yellow-green color.

 

lungAir Chamber (demonstration)

The model shown here simulates the contraction of the diaphragm (the plastic swim cap) and the resulting rush of air into the lungs (the balloon inside the bottle). Build one yourself so students can visualize the process that take place in their chest cavity.

Materials

  • 2-liter bottle with the bottom cut off
  • Hammer and nail to poke a hole in the lid
  • A straw inserted into this hole and secured in place with clay or glue
  • A balloon taped securely onto the other end of the straw
  • A swim cap held in place with a rubber band

When you inhale, your diaphragm, a band of muscles at the bottom of your chest cavity, contracts. When your diaphragm contracts, it flattens and pulls downward – just like when you pull down on the plastic swim cap on the bottom of the model. As it does, the volume of your chest cavity increases and the pressure inside it decreases. The pressure of the air outside your body is then greater than the pressure inside the chest cavity, so air rushes in through your mouth and nose.

When you exhale, your diaphragm relaxes and returns to its original shape, decreasing the volume and increasing the pressure of air in your chest cavity. This forces air out of your lungs.

Lung Capacity Activity

In advance, I calibrated a clean plastic milk jug (marking off 1-cup increments with a permanent marker on the side). I then inverted it in a sink about half full of water, being careful so that the water doesn’t come out of the jug. Holding the jug steady so it doesn’t fall over (another set of hands is helpful), I inserted a long rubber tube (approximately 60cm) into the jug.

I then asked for a volunteer to take a big breath and exhale into the open end of the tube. As he blew, the water inside the jug was forced out and replaced with the air he exhaled (Carbon Dioxide and other trace gases). We were then able to measure the amount of air he breathed out using the change in water level.

Bring it Home

  • Measure your own lung capacity using a calibrated milk jug as I described above. How does your lung capacity compare to that of your parents or siblings? your friends?
  • How does your lung capacity change with exercise?
  • Why do some athletes (distance runners) train at high altitudes?
  • What is Emphysema, Pneumonia, Bronchitis and Sinusitis?

 

STEM Club: The Digestive System

The Digestive System is a group of organs working together to convert food into energy and basic nutrients to feed the entire body. Food passes through a long tube inside the body known as the alimentary canal or the gastrointestinal tract (GI tract). The alimentary canal is made up of the oral cavity, pharynx, esophagus, stomach, small intestines, and large intestines.

There are several important accessory organs that help your body to digest food but do not have food pass through them. Accessory organs of the digestive system include the teeth, tongue, salivary glands, liver, gallbladder, and pancreas. To achieve the goal of providing energy and nutrients to the body, six major functions take place in the digestive system:

  • Ingestion
  • Secretion
  • Mixing and movement
  • Digestion
  • Absorption
  • Excretion

There are two types of digestion – mechanical (chewing, stomach sloshing, peristalsis, etc.) and chemical. Chemical digestion is only possible because your body gets help from enzymes! An enzyme is a type of protein that speeds up how quickly a chemical reaction happens in your body.

digestivesystemEnzyme Labs

Amylase

There are about 700 different enzymes in the body. Amylase is an enzyme that breaks down complex carbohydrate molecules into simpler, sugar molecules. Our salivary glands excrete amylase into our mouth to aide in the digestive process.

Activity 1 :: In the book Head to Toe Science, I came across an activity that I thought would be perfect for STEM Club that was titled “Helpful Spit”. We thereby carried out this activity in class using the following procedure:

  • Divide a plate into four quarters, labeling them as follows: unthawed, 30 seconds, 5 minutes, and 10 minutes. Place a soda cracker in the unchewed section. Place a drop of iodine on the cracker. What happens?
  • Chew another cracker for 15 seconds making sure it becomes well moistened. Place one-third of the chewed cracker in each of the remaining sections. Wait 15 seconds. Place a drop of iodine on the cracker in the 30 seconds section. What happens?
  • Wait five minutes. Place a drop of iodine on the cracker in the 5 minutes section. What happens? Wait another 5 minutes and place a drop of iodine on the cracker in the 10 minutes section. What happens?

Iodine is a chemical that turns dark blue or black when it reacts with starch. We thereby expected the iodine to react with the unchewed cracker by turning dark blue/black and this is exactly what happened.

Saliva is an enzyme present in our saliva and thus the longer it had time to break down the carbohydrates into simple sugar molecules, the less starch would be present to react to the iodine.  We thereby expected that the chewed crackers would show a lighter shade of blue the longer the chewed crackers were left on the plate.

However, there was no discernible difference. Activity fail. We hypothesized what could have gone wrong. What could have affected the outcome of this activity? Not enough saliva? Not enough time?

We tried it again a few days later – assuring the crackers were significantly more moist (more saliva) but again, the same result.

Activity 2 :: An Alternative

Materials:

  • 2 teaspoons starch powder
  • 1 teaspoon amylase powder
  • Distilled water
  • 2 small glasses
  • 1 spoon or stick with which to stir
  • 2 – 3 glucose testing strips (Lab-grade, with color-coding section)

Procedure:

  1. Pour 1 teaspoon of starch powder into each glass.
  2. Label one glass “WA” (with Amylase) and the other “NA” (no Amylase).
  3. Add about 5 mL of distilled water to each glass, stir to mix.
  4. To the glass marked “WA”, add your 1 teaspoon of Amylase powder and stir to combine thoroughly.
  5. Place 1 glucose testing strip into each glass. Record the color that the testing strips turn for each glass; refer to the color-code on the package to determine how much glucose is present in the solution.

Pepsin

Pepsin, which is found in the stomach, breaks down proteins. It takes the proteins from complex structures into simpler structures. Once those simple proteins get to the small intestine, a number of other enzymes continue to break them down into amino acids – which your body loves.

Materials:

  • 1 small piece of tough steak
  • 1/8 teaspoon meat tenderizing powder
  • 1 plate

Procedure:

  1. Using a small knife, carefully cut your steak into two pieces.
  2. Place the steak on the plate, and using your masking tape and markers, label one piece “WP” (with Pepsin) and the other “NP” (no Pepsin).
  3. Carefully sprinkle / cover your steak marked “NP” with the meat tenderizing powder and let it sit.
  4. After several minutes, the meat tenderizers should have had time to do their work. Touch both pieces of meat and record any differences between them in your notebook. What difference do you feel?
  5. Do you think that other animals have adaptive digestive systems that might be different from ours? Imagine a creature’s digestive system based on a diet of either: rocks and stones, twigs and leaves, or only meat. Explain how their digestive system is different from ours, naming all of the organs and how they are different based on the diet that you chose.
  6. Many commercial meat tenderizers (powders that you can put on your steak before cooking it to make the meat more tender) contain enzymes, like the enzyme “papain” which comes from the papaya fruit. What is this analogous to in the human digestive system? How?

Bring it Home

  • Make a record of what you eat each day for the week. Compare your diet tot the recommended daily requirements. What kinds of foods are you eating?
  • Make a cast of your teeth with plaster of Paris.
  • If you have a tooth, crack it open gently by tapping with a hammer and look at the internal parts (enamel, dentin, pulp).
  • Watch this great TED-Ed video, What does the liver do? Write a paragraph describing what you learned.
  • Eggshells are similar in their makeup to teeth; both react to acid in a dramatic way. Design a test to see how different soda pops affect the egg shell.
  • Create a “Wanted” poster for a digestive organ (include the following information:
    • The organ’s role(s)/function(s) in the digestive system
    • The type(s) of digestion it performs
    • What enzymes it utilizes
    • What would happen to your digestive process if you no longer had this organ
  • Test a variety of foods to find what group, or groups, to which your favorite foods belong:
    • Test for Fat: Cut up some brown paper squares. Rub food on the paper and let it dry. If fat is present, light will show through.
    • Test for Starch: Put a drop of iodine tincture on the food. If starch is present, the iodine will turn blue/black.
    • Test for Protein*: Add the food to a solution of potassium or sodium hydroxide. Add a few drops of diluted copper sulfate solution. If protein is present, you will see a pink or bluish color.

*This test requires some chemicals that you may not have. Adult assistance recommended.

STEM Club: The Muscular System

muscular system

The Muscular System

The muscular system is responsible for the movement of the human body. Attached to the bones of the skeletal system are about 700 named muscles that make up roughly half of a person’s body weight. Each of these muscles is a discrete organ constructed of skeletal muscle tissue, blood vessels, tendons, and nerves. Muscle tissue is also found inside of the heart, digestive organs, and blood vessels. In these organs, muscles serve to move substances throughout the body. There are three types of muscle tissue: visceral, cardiac, and skeletal.

Visceral Muscle is found inside of organs like the stomach, intestines, and blood vessels. The weakest of all muscle tissues, visceral muscle makes organs contract to move substances through the organ. Because visceral muscle is controlled by the unconscious part of the brain, it is known as involuntary muscle—it cannot be directly controlled by the conscious mind. The term “smooth muscle” is often used to describe visceral muscle because it has a very smooth, uniform appearance when viewed under a microscope. This smooth appearance starkly contrasts with the banded or striated appearance of cardiac and skeletal muscles.

Cardiac Muscle is found only in the heart, cardiac muscle is responsible for pumping blood throughout the body. Cardiac muscle tissue cannot be controlled consciously, so it is an involuntary muscle. While hormones and signals from the brain adjust the rate of contraction, cardiac muscle stimulates itself to contract.

The cells of cardiac muscle tissue are striated—that is, they appear to have light and dark stripes when viewed under a light microscope. The arrangement of protein fibers inside of the cells causes these light and dark bands. Striations indicate that a muscle cell is very strong, unlike visceral muscles.

Skeletal Muscle is the only voluntary muscle tissue in the human body—it is controlled consciously. Every physical action that a person consciously performs (e.g. speaking, walking, or writing) requires skeletal muscle. The function of skeletal muscle is to contract to move parts of the body closer to the bone to which the muscle is attached. Most skeletal muscles are attached to two bones across a joint, so the muscle serves to move parts of those bones closer to each other.

Skeletal muscle cells form when many smaller progenitor cells lump themselves together to form long, straight, multi-nucleated fibers. Striated just like cardiac muscle, these skeletal muscle fibers are very strong. Skeletal muscle derives its name from the fact that these muscles always connect to the skeleton in at least one place.

musclegroupsExercising Muscle Groups – Whole Group Demonstration

The kids had a lot of fun with this activity – I hadn’t expected that they would enjoy it so much. In groups of three, students took turns to do a few lifts I first demonstrated. I chose to do bicep curls, bench press, and squats – but any weight lifting exercise will work.

Students should choose weights which are comfortable to use, but heavy enough to do 15-20 reps. Students rotate three times (each time a new exercise is demonstrated) so students have the opportunity to do each task.

  • The lifter of each group will slowly lift the weight up and down in a “bicep curl” with their dominant arm.
  • The other group members will observe all muscle groups working/moving while the lifter is doing the bicep curls. One member can use a skin-safe marker to circle the muscles that are being used.
  • All students should then write down exactly what type of movements the group observed while the bicep curls were happening.

Students should then switch group roles, and then repeat the steps listed while performing a “bench press” exercise with the weights and finally the “squats”.

Encourage students to make a sketch of what they believe the circled muscles should look like after recording their observations and circling the muscle groups that are moving on the arms of the lifters. Students will need to consider where each muscle connects to the bones in order for them to be activated during each different exercise movement.

Muscle Fatigue Lab – How does fatigue affect performance?

I then led the group through a lab activity that is perfect for integrating math skills – graphing, finding mean and range, and finding percent of decrease and increase. I was the timer for the whole group and I trusted each student to count

Each student places their right forearm flat on a table so the back of the fingertips are flat on the tabletop. He/she closes and opens the right hand as fast as possible until the timer says stop, being sure the fingertips touch the palm when closed and the fingertips touch the table when open.

The timer times each trial for 30 seconds and upon calling stop, students record their count on a data table or chart in their notebook. This process is repeated for six 30-second intervals with one 30-second rest interval between the 3rd and 4th trial.  After the activity has been completed for the right hand, repeat the steps for the left hand.

Using the data collected students are then instructed to create a graph. The data and graph can then be used to discuss the results of the activity.

Bring it Home

  • Calculate your horsepower. Weigh yourself on a bathroom scale (pounds). Measure the vertical height of a flight of stairs (meters). Use a stopwatch to record the time it takes you to walk up the stairs (one step at a time). Calculate your weight in newtons (your weight in pounds multiplied by 4.45). [A newton is a unit of force – in this case, the force of gravity that you must overcome to climb the stairs.] Calculate the work you did climbing the stars in joules (your weight in newtons multiplied by the distance or height of the stairs). Calculate the power in units called watts (work in joules divided by the amount of time it took). Lastly, calculate the horsepower used by dividing the watts by 746 [one unit of horsepower (hp) is equal to 746 watts] .
  • Gluteus maximus, soleus, sartorius – why do we call muscles by Latin names?
  • Keep an exercise chart for one week. At the end of the week, evaluate your effort. How well are you exercising? Write a good health goal to improve. List three steps you can take to reach your goal.
  • Are you an athlete? A swimmer, runner, or basketball player for example. Research the muscle groups that are most used by athletes in your sport of choice and write a 5-paragraph essay describing how these muscles are used and what one can do to strengthen these muscles. This activity choice will count for two points.
  • What is muscular dystrophy?
  • Present a simple exercise routine done to your favorite music.
  • Interview a coach and ask about sports-related injuries to the muscular system. Share what you learned with the class.
  • Take a poll. Ask your friends and family how much time they spend on daily exercise. Create a graph to share the results.
  • Learn how to control the muscles in your face. Find a diagram online or in a reference book of the facial muscles. What muscles do you use to: a) open / shut nostrils, b) pull scalp back / down, c) pull ears back, d) raise ears, e) open mouth wide, f) wink with one eye, then the other, g) pull top lip down, and h) pull mouth corners up / down.
  • Cut apart a chicken leg (drumstick and thigh still attached) and carefully observe how they are attached to the bone. Also look at the joint. Sketch and label in your notebook
  • If you and your child think of other activities, go for it!!

My kiddos wanted to create a skit to share what they had learned about the importance of dynamic stretching before exercise as well as what to do in case of a sports related injury. Here is their video that I originally posted to Facebook:

Next week in STEM Club, we will explore the Digestive System.