Fetal Pig Dissection Summative Lab

Preamble:

Like humans, the pig is a placental mammal, meaning that the fetus receives nourishment from the mother through the umbilical cord. In this investigation, you will study the circulatory, digestive and respiratory systems of the fetal pig. Because the anatomy of the fetal pig resembles that of other placental mammals, this activity serves two important functions: it provides a representative overview of vertebrate anatomy and it provides the framework for understanding functioning body systems.

Requirements

Title– be clear, specific and include more detail than you probably think you should

Purpose– what is the purpose of the lab? Your purpose need to be specific and clear.

Materials– list all items used

Observations– For each of the following include a complete and labelled diagram and corresponding questions if required:

(1)external anatomy with questions

(2)internal anatomy

(3)digestive system with questions (there should be 2 diagrams for this section, one of the digestive system IN SITU and the other using a stereoscopic microscope on the small intestine).

(4)excretory/urogential system with questions

(5)circulatory system with questions (there should be 2 diagrams for this section, one of the heart IN SITU and the other with the front of the heart cut away).

(6)breathing system with questions

(7)miscellaneous - if you have the time (brain, eye, ear)

This is not about outstanding artistic quality, but your work must reflect care and neatness. There should be a minimum of 8 diagrams.

Discussion

You are expected to apply your understanding of the material as well as researching for information to supplement your answers. Your answers should be clear, concise, and use proper citations should you use outside sources. Each answer is expected to be 1-2 paragraph in length.

CHOOSE AT LEAST 2 QUESTIONS FROM THE FOLLOWING CLUSTERS; YOU SHOULD ANSWER A TOTAL OF 10 QUESTIONS:

Cluster 1: Homeostasis and internal balance - ANSWER ONLY 2

  1. Homeostasis, maintaining a steady-state internal environment, is a characteristic of all living organisms. Choose three of the following parameters and for each, describe how homeostasis is maintained in an organism of your choice. Be sure to indicate what animal you have chosen for each parameter. You may use the same animal or different animals for your three descriptions.

Blood-glucose levels / Body temperature / pH of blood / Osmotic concentration of the blood
  1. Explain the effect of temperature on the metabolic rate of ectotherms (e.g. fish). Connect your answer to include the effect on fish that a power plant will have which releases warm water into a large lake.
  2. What is the function of lymph? How does it work?

Cluster 2: Heart and Circulation - ANSWER ONLY 2

  1. Trace a drop of blood through the human circulatory system starting and ending in the right atrium.
  2. Name some adaptive advantages of the mammalian circulatory system (compare to a fish and amphibian). How do you think these adaptations benefit mammals? Why is the mammalian system of blood circulation considered the most efficient out of these examples?
  3. Hormones are important in facilitating human life. Using evidence, give an example of a hormone that effect the heart and its function. Why is this hormone important?

Cluster 3: Digestion and Nutrients - ANSWER ONLY 2

  1. Trace a polysaccharide through the human digestive system. Explain what is happening at each of the main stages along the way.
  2. Which of the sections of the small intestine are most important? Justify your answer with reasoning.
  3. Explain why a 100% fat free diet is virtually impossible to attain, and why it might be an unhealthy choice.
  4. What is glucagon and what is its function? How does its function compare to another pancreatic hormone, insulin?

Cluster 4: Respiration and Breathing - ANSWER ONLY 2

  1. Countercurrent flow aids gas exchange and temperature regulation. Explain how countercurrent flow in a fish’s gills is similar to what you would expect to find in the leg circulation of a penguin.
  2. Trace the path taken by a molecule of O2 as it moves from the atmosphere outside the body arriving at a muscle cell.
  3. What is diffusion and what are some factors that improves the efficiency of this process? Using an organism of your choice, explain how diffusion facilitates its respiratory processes.

Cluster 5: Disease and Ethics - ANSWER ONLY 2

  1. Describe a disorder related to the each of the respiratory, digestive, and circulatory systems. Include causes, symptoms, diagnosis, treatments, etc.
  2. Do you agree with dissecting fetal pigs in high school? Consider opposing opinions, and justify your opinion based on evidence in at least two paragraphs.
  3. Knowing how similar animals are to people, what is your opinion on euthanizing(mercy killing) animals that are sick, disabled, or abandoned? Justify your opinion based on evidence in at least two paragraphs.

Works Cited– include all references used in Works Cited sheet. Make sure to include in-text citations in your discussion.

Checklist

November 3: Read the fetal pig dissection guidelines and p. 308 – 312 of your textbook. Begin work on discussion questions.

November 6-10: Create all labelleddiagrams as required in class, and make additional touches to diagrams at home. Work on discussion questions at home.

November 14: Full work class in library. Submit final copy of your lab including all parts described above on Tuesday,November 14th.

Learning Skills and Work Habits

Learning Skills
and Work Habits / Excellent / Good / Satisfactory / Needs Improvement
I fully use this learning skill/work habit to reach my potential in this course. / I use this learning skill/work habit to reach my potential in this course a lot of the time. / I know this skill/habit is important for me to reach my potential but I have to be reminded about it. / I don’t show that I know this skill/habit is important for me to reach my potential.
Responsibility
- Does class work within the set timelines
- Records own set of lab results during the lab
- Takes responsibility for share of lab work and clean up
- Follows lab procedures carefully and repeats steps, as necessary; does not take short-cuts or rush through the activity
Organization
- Comes prepared for lab activities by having read pre-lab materials
-Respects deadlines by setting priorities
- Asks specific questions when tasks are not clear
Independent Work
- Uses time wisely during work periods and respects classmates’ work time
- Follows instructions with minimal supervision
- Displays a positive work ethic
Collaboration
- Accepts equitable share of work in a group
- Shares ideas and promotes critical thinking to develop ‘thinking’ questions for discussion

Lab Report Marking Scheme

Criteria / Explanation / Level
Knowledge
Title & Problem / Lab Technique / Observations /
  • Clear, concise direction is given to the lab through problem & title.
  • Safe and competent skills are demonstrated throughout the lab.
  • Thorough, high quality, qualitative labelled diagrams. There should be 8.
  • Answers to questions within the observation section.
/ 0 1 2 3 4
0 1 2 3 4
0 4 8 12 16
0 3 6 9 12
Inquiry
Materials / Procedure /
  • Materials list is appropriate and complete.
  • Effectively followed and attended to Procedure.
/ 0 1 2 3 4
0 1 2 3 4
Application
Discussion Questions /
  • Thorough answers to discussion questions.
/ 0 5 10 15 20
Communication /
  • Spelling, grammar, scientific terminology, presentation, organization and completeness.
  • Complete works cited and in text citations in CSE format.
/ 0 2 4 6 8
0 1 2 3 4
Level 4 – ExcellentLevel 3 – GoodLevel 2 – Satisfactory
Level 1 – Limited Level 0 – Incomplete Total / /76

Dissection of the Fetal Pig Guide

  1. INTRODUCTION

The fetal pig is an excellent representation of the vertebrate body pattern, having internal organs almost identical to human organs in location and arrangement. The organs are large and distinct, making it an easy animal to dissect.

  1. Keep this dissection guide in front of you as you work. You will be asked to present your dissection for examination at several points in the dissection process, so follow the instructions.
  2. Note that the names of organs are in CAPITAL LETTERS the first time they are mentioned. You might want to highlight these words to make them stand out.
  3. Work in groups of three. No more or less.
  4. The preservative the pigs are in has a bit of a smell to it, but it is not harmful and washed off very easily. Students who are doing the dissection should be wearing gloves, no one else needs to.
  5. Make all cuts carefully and never cut or remove anything unless you are sure. You can not put things back.
  6. Record your answers neatly, in sentences. Diagrams should be full page unless otherwise stated. Diagrams can be hand drawn or labelled pictures that you have taken.
  7. At the end of each lab, CLEAN UP! Pigs are to be left on the trays with pins in them and trays are to be labelled. All other dissecting instruments are to washed off and left to dry. Bits and pieces are to be put in the garbage, please do not put them in the sink.
  1. EXTERNAL ANATOMY

When you first get your pig, rinse it off thoroughly. Give it a name (if you wish), and place a label on your tray so you know which pig is yours.

  1. BODY
  1. Note the parts of the body: HEAD, NECK, TRUNK, TAIL.
  2. Note the divisions of the trunk: THORAX, ABDOMEN
  3. Note the cut UMBILICAL CORD, and the BLOOD VESSELS within it. See if you can count the blood vessels.
  4. The ANUS is located under the tail.
  1. HEAD
  1. Find the EXTERNAL EARS, EYES, EYELIDS, MOUTH, TONGUE, SNOUT and NOSTRILS.
  1. APPENDAGES
  1. Note the DIGITS on the FEET, and the HOOF at the tip of each digit.
  2. Find the WRIST just above the digits of the FORELEG.
  3. Above that is the ELBOW, and above that, the SHOULDER. Try to feel the shoulder by locating the SCAPULA, or shoulder blade.
  4. In the HIND LEG, the ANKLE is just above the digits. Higher up, the KNEE corresponds to the elbow on the foreleg. The HIP can be found high in the body by feeling for the PELVIS.
  1. SEX

Determine the sex of your specimen. Note both sexes have two rows of TEATS, or nipples, along the abdomen.

  1. Males – a swelling just below the tail and anus, the SCROTUM and the UROGENITAL OPENING just behind the umbilical cord identify the males. Also, you can feel a tough cord under the skin running back from this opening towards the scrotum. This is the PENIS.
  2. Females – the UROGENTIAL OPENING is just below the tail and anus. A fleshy PAPILLA protrudes from the opening.
  1. QUESTIONS
  1. What is your pig’s name?
  2. How long is your pig in centimetres? Think carefully how to do this without putting a ruler on the pig.
  3. What is the genus and species of the pig?
  4. What obvious physical structure does the pig possess that tells you it is a vertebrate?
  5. What 3 obvious structures can you see on the pig that tells you it is a mammal?
  6. What is the gestation period of a pig? Where do you think your pig is within the gestation period?
  7. The pig is an “ungulate”. What does that mean? How many “digits” does the pig have on each foot?
  8. The hooves are horny structures at the tips of the toes. What human structure at the tips of our toes do the pig’s hooves correspond to?
  9. Does your pig have a curly tail? Are the pigs supposed to have curly tails? Is there something wrong with our pigs for not having a curly tail?
  10. Is there any difference in the number of teats on a male or female pig? If there is, what accounts for this?
  11. All male mammals have teats, even though they will never produce milk. So why do they have them?
  12. The torso is divided into 2 regions. Name the two regions. What structure acts as the divide between the two regions? In which region is the heart?
  1. DIAGRAM

Prepare a large (1 page) diagram to show the external appearance of your pig. Carefully label the following structures:

  1. BODY REGIONS: Head, Trunk, Tail
  2. HEAD: Ears, Eyes, Mouth, Tongue, Snout, Nostrils
  3. DIVISIONS OF THE TRUNK: Thorax, Abdomen
  4. UMBILICAL CORD
  5. ANUS
  6. APPENDAGES: Forelegs, Hindlegs, Toes, Hooves
  7. SEX: Males – Scrotum, Urinary/Reproductive Opening, Teats

Females – Urinary/Reproductive Opening, Papilla, Teats

  1. INTERNAL ANATOMY

First you must open the body cavity. How you do this depends on whether the pig is male or female.

  1. FEMALE PIGS
  1. Begin at the small hairy papilla under the jaw. Cut back toward the umbilical cord. Cut around the cord on both sides. Resume a single cut behind the cord to a point between the hind legs.

NOTE: Start with a shallow cut. Then repeat, going a little deeper each time, until you break through into the body cavity.

  1. MALE PIGS
  1. Cut back to the umbilical cord as described above. Cut around the umbilical cord, but do not resume a single cut. Continue with two cuts back between the hind legs. You must avoid cutting the penis, which runs down the midline.

ANOTHER NOTE: When you break into the body cavity, you may find a fluid comes out. This can be washed away once the body cavity has been fully opened.

  1. ALL PIGS
  1. Cut the skin and tissue away from the pig, exposing the internal organs from throat to abdomen. Cut enough away so that you can see into the body cavity without having to push skin out of the way.

FINAL NOTE: Notice that the umbilical cord can not be moved out of the way. Look for the UMBILICAL VEIN running forward into the liver. Cut this vein. You can now lay the umbilical cord back between the hind legs. Wash everything off.

  1. IDENTIFYING THE ORGANS OF THE BODY CAVITY

Start with the LIVER: It is the most obvious organ. A huge brown gland right in the middle of the body.

GALL BLADDER: a small sac embedded in the underside of the right LOBE of he liver.

STOMACH: a large sac under the liver , on the pig’s left side.

PYLORIC VALVE: feel the muscular lump at the left end of the stomach, at the exit to the small intestine.

ESOPHAGUS: Not really in the abdomen, but visible under the trachea in the thorax, if you move the trachea aside.

THYROID GLAND: a small reddish-brown ball where the trachea meets the larynx.

THYMUS GLAND: a mass of mushy tissue in the throat, on either side of the trachea, that extends down over the heart.

HEART: this is a large, muscular ball between the two soft lungs. Look for CARDIAC ARTERIES on its surface.

LUNGS: the lungs are fleshy and triangular, divided into many lobes on either side of the heart.

DIAPHRAGM: looks like a piece of skin between the lungs and the liver. It divides the thorax from the abdomen.

PANCREAS: a granular, whitish mass under the stomach. You will have to pull the intestines away from the stomach to find it.

SPLEEN: The organ looks like a long, flat brown leaf attached to the left side of the stomach.

DUODENUM: the first section of the small intestine before the main mass. It leaves the stomach at the pyloric valve.

SMALL INTESTINE: most of the coiled intestine mass.

LARGE INTESTINE: a greenish, tightly coiled mass of intestine separate from the small intestine.

RECTUM: a greenish tube embedded in the back wall of the abdomen, right down the centre line. Move the intestine out of the way to find it.

URINARY BLADDER: this is the long sac that you should have folded back between the hind legs.

  1. DIAGRAM

Prepare a large (1 page) diagram to show the internal organs of your pig IN SITU (this means in their proper positions, except for the urinary bladder, which you should have folded back between the hind legs). Label all of the structures that you identified in the section above.

  1. DIGESTIVE SYSTEM
  2. MOUTH

Cut the corners of the jaw so that the jaw can be dropped and the interior of the mouth can be examined. Spend a few minutes examining the following structures:

  1. TONGUE: look for the PAPILLAE (bumps) which contain the taste buds.
  2. TEETH: count the number of teeth that have “erupted” from the gums of your pig. Cut into the gums and find a few UNERPUTED TEETH. Mammals have 4 types of teeth however your pig may be too young to have all of them.
  3. HARD PALATE: this is the bony, ridged roof of the mouth.
  4. SOFT PALATE: this is the soft region behind the hard palate.
  1. PHARYNX

Bend the jaw back as far as it will go (perhaps even further) and look for the following:

  1. OPENING FROM NASAL CAVITY: this looks like a small hole in the soft palate. Cut the soft palate away and find the nasal cavity. Cut forward through the hard palate and examine the NASAL PASSAGES.
  2. OPENING TO THE ESOPHAGUS: This is sometimes called the GULLET. Insert a probe and try to see it in the esophagus, underneath the trachea.
  3. OPENING TO THE TRACHEA: Find the small flap of cartilage which protects this opening. This is the EPIGLOTTIS. Insert a probe into the actual opening, the GLOTTIS, and try to see it in the trachea.
  1. QUESTIONS
  1. How many salivary glands does the pig have altogether? How does that compare to humans?
  2. What are the 4 types of mammalian teeth? What are “DECIDUOUS TEETH”?
  3. Both you and the pig have a hard and soft palate. How do these two palates differ? What is a cleft palate?
  4. What is the purpose of the epiglottis?
  1. STOMACH
  1. Find where the esophagus emerges from under the liver and cut it here. Also cut through the DUODENUM and remove the stomach from the body.
  2. Identify the point where the esophagus enters the stomach. Feel the solid mass of muscle. This is the ESOPHAGEAL SPHINCTER muscle. Find where the duodenum leaves the stomach. Feel the solid mass of muscle. This is the PYLORIC SPINCTER muscle.
  3. Cut the duodenum and stomach (be careful, it contains liquid) in half around the edge of this ring of muscle. Also examine the internal surface of the stomach. Look for ridges and folds called RUGAE.
  1. SMALL INTESTINE
  1. The small intestine is composed of 3 regions, but only one is quite distinct, the duodenum. The duodenum is the first, short section of the small intestine after the stomach and remains free from the main mass of intestines.
  2. Examine the tissues holding the small intestines to one another. Note the numerous blood vessels in these tissues.
  3. Remove the mass of intestines from the body. Very carefully cut the connective tissue to free up the intestine and stretch it out. Record the length of the small intestine.
  1. DIAGRAM

Cut a small segment of the intestine out of the mass of intestines, flatten it out and examine it under water using a stereoscopic microscope. You are looking for the VILLI.