7th grade final exam Pig dissection

Mrs. Riesterer

1st hour

2013

Safety & Reminders

• No horseplay in the lab• Always wear gloves, if yours

gets a hole get a replacement

• Clean up your area and disinfect everything that is in your area (including the tools you used)

• Place your pig in a plastic (sealed) bag and label it with your group/pigs name

• Wear lab apron and eye goggles at all times

• Make sure you have the following in your lab station daily:– Dissecting pan– Dissecting scalpel– Dissecting scissors– Dissecting pins– Dissecting forceps– Dissecting probe– Measuring tape– Your pig

Day 1 – external anatomy

» Ventral surface

» Lateral surface

» Dorsal surface

» Anterior end

» Posterior end

• Obtain a fetal pig and rinse off the excess preservatives by holding it under water.

• Lay pig on its side in the dissecting pan and locate the:

Day 1 – external anatomy

• A fetal pig is a pig that has not been born yet, but its approximate age since conception can be measured by measuring its length.

– Measure from the tip of the pigs snout to the base of the pigs tail.

– Use the chart that is on the board to figure out how old your pig is

• Examine the pigs head. Locate the following:– External nostrils

– External ears (pinnae)

• Look at the pigs appendenages– How many toes does the pig have?

– Is there a difference between the front and the hind hooves

• Observe the eyes of the pig – carefully remove the eyelid so that you can view the eye underneath– Does it seem well developed

– Do you think pigs are born with their eyes open or shut?

Day 1 – external anatomy

• Locate the umbilical cord. Use the dissecting scissors to cut across the cord 1 cm from the body.

• Determine the sex of your pig

– Locate the urogenital opening through which wastes and reproductive cells pass through.

• Males – the opening is on the ventral side of the pig just posterior to the umbilical cord.

• Females – the opening is ventral to the anus

Day 1 – external anatomy

• Carefully lay the pig on one side in your dissecting pan and cut away the skin from the side of the face and upper neck to expose the following (label them on your handout):

» Masseter muscle (muscle that works the jaw)

» Lymph nodes

» Salivary glands

• With your scissors, make a 3 cm incision in each corner of the pig’s mouth – your incision should extend posteriorly through the jaw.

Day 1 – external anatomy

• Spread the jaws and examine the tongue

• Notice the palate on the roof of the mouth– Anterior part is the hard palate

– Posterior part is the soft palate

• Notice the taste buds (sensory papillae) on the side of the tongue

• Locate the esophagus at the back of the mouth

• Feel the edge of the pigs mouth. Are there teeth? Are humans born with teeth?

Day 1 – external anatomy

• Clean up your materials and lab stations. Get a plastic zip-lock bag from Mrs. Riesterer and label it with your pigs name.

• Wrap the pig in damp paper towels and put it in a zip-lock bag.

• Return the equipment (once cleaned and disinfected) to the proper location.

• Wash your hands thoroughly with soap and water.

Day 1 – wrap up

• Place the pig in the dissecting pan, ventral side up

• Tie a string securely around a front limb. Run the string under the tray, pull it tight & tie it to the other front limb. Now repeat with the hind limbs.

Day 2 – internal anatomy

Day 2 – internal anatomy

• Use your scissors to cut through the skin and the muscle according to the diagram.

• Do NOT remove the umbilical cord.

• Be careful not to cut too deep.

• You may need to “drain” your pig to remove any preservatives that are still inside the pig, but make sure no organs fall out.

• Locating organs:

– The liver (brownish color), count the number of lobes.

– The esophagus (tube-like), joins the mouth to the stomach

– The stomach – located beneath the liver

• Carefully cut along the outer curve of the stomach –note the texture of the inner walls.

Day 2 – internal anatomy

• Identifying more organs:– Small intestine – connected to the stomach

• Carefully cut through the small intestine (at the small end only) and uncoil it.

• Measure its length and record that on your data sheet• With your scissors cut a 3cm piece of the lower small intestine.

Cut it open and rinse it out.

– Large intestine – follow the small intestine until it reaches the wider, looped intestine. • Unwind the large intestine and measure its length.• how do the length of the 2 intestines compare to each other? Is

this what you expected from what you learned in class.• Notice that the large intestine leads to the rectum.

Day 2 – internal anatomy

• Locate more organs

– Locate the thin, white pancreas beneath the stomach.

– Between the lobes of the liver, find the small greenish-brown gall bladder.

– Find the spleen, a long, reddish-brown organ wrapped around the stomach. Remember the spleen filters out old red blood cells and produces new ones for the fetus.

Day 2 – internal anatomy

• Clean up your materials and lab stations. Get a plastic zip-lock bag from Mrs. Riesterer and label it with your pigs name.

• Wrap the pig in damp paper towels and put it in a zip-lock bag.

• Return the equipment (once cleaned and disinfected) to the proper location.

• Wash your hands thoroughly with soap and water.

• Complete the organ fill in sheet for homework

Day 2 – wrap up

• Locate the heart – notice that the pig as a four chamber heart just like all other mammals.– The right side of the heart pumps blood to the

lungs, while the left side of the heart pumps blood to the rest of the body

– Each side of the heart has an upper and a lower chamber. Upper chambers are called atria and receive blood, while the lower chambers are called ventricles and they pump blood out of the heart.

Day 3 – circulatory system

• Find the pulmonary artery which leaves the right ventricle. After birth, this vessel carries blood to the lung.

• Find the pulmonary veins that enter the left atrium. After birth, these vessels carry blood from the lungs to the heart.

• Identify the aorta, a large artery that transports blood from the left ventricle.

Day 3 – circulatory system

• Remove the heart by severing the blood vessels attached to it.

• Hold the dorsal and ventricle surfaces of the heart with your thumb and forefinger and rest the ventricles on your dissecting pan. With a scalpel, cut the heart into dorsal and ventricle halves.

• CAUTION: the scalpel is very sharp. Use it carefully and always cut away from yourself.

Day 3 – circulatory system

• Remove any material inside the heart and expose the walls of the atria and the ventricles.

• Study the internal features of these chambers and note where vessels leave or enter each chamber. Locate the valves between each atrium and ventricle. These structures prevent blood from flowing backward in the heart.

Day 3 – circulatory system

• Clean up your materials and lab stations. Get a plastic zip-lock bag from Mrs. Riesterer and label it with your pigs name.

• Wrap the pig in damp paper towels and put it in a zip-lock bag.

• Return the equipment (once cleaned and disinfected) to the proper location.

• Wash your hands thoroughly with soap and water.

• Complete the heart fill in sheet for homework

Day 3 – wrap up

References

Martin, Phillip. Free Clip Art. N.p., n.d. Web. 7 May 2013. <http://animals.phillipmartin.info/animal_pig2.html>.

Muskopf, Shannan. The Biology Corner. N.p., 2001. Web. 6 May 2013. <http://www.biologycorner.com>.