In this rap you"ll dissect a fetal pig to get a look in ~ the anatomy of a mammal. In addition, you have to study the 2 pre-dissected specimens easily accessible in lab.

You are watching: Function of larynx in fetal pig

Objectives

Recognize the structures labeled top top the photos on this page or provided in bolder in the text.

Specimens

Fetal pig that you deserve to dissect v your groupPre-dissected pig in plastic caseSagittally sliced pig sealed in plastic

Fetal pig, dissected

We have a dissected specimen in lab, kept in a plastic case. This would be a an excellent one because that the lab exam. Top top the photo below, I"ve labeling some frameworks that I can potentially ask you around on the lab exam.

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Fetal pig sagitttal section

Here"s another specimen obtainable in lab.

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Dissect your own pig

The finest online guide to fetal pig dissection is most likely the online Fetal Pig Dissection in ~ Whitman College. I recommend using that together your guide.

Here room some features you should look for:

Determine the sex of your pig

Before you start dissecting, study the exterior of the pig and also determine that sex. Look for these features:

Males: Urogenital opening is situated near the umbilicus; the prick is concealed inside. The scrotal sac might be visible together a swelling just ventral to the anus, depending on the period of the fetus.The testes are still deep inside the body cavity; lock don"t descend into the scrotal sac until later.Females: Look because that the urogenital papilla, situated just below the anus.

Both males and also females have actually nipples, simply as in humans.

Reference: Sexing your pig.

Neck region

Begin your dissection in the neck region. Try to cut as little as possible. Once you open up the body cavity, you will certainly generally have the ability to separate the different organs by merely pulling lock apart v your fingers, forceps, or a probe. The an ext you cut things up, the more tough it will certainly be to figure out what she looking at. Cut midline on the ventral surface ar of the neck to disclose the basic muscles. Carefully separate the muscles to observe the underlying structures. Locate and also understand the attributes of the following structures:

Larynx: an enlarged framework on the trachea. If you reduced it open, you have the right to see the vocal cords inside.Thymus gland: one endocrine (hormone-secreting) gland that helps regulate the immune system. The a large, spongy structure covering the ventral surface of the trachea and often expanding into the thoracic cavity surrounding to the heart.Thyroid gland: an additional endocrine gland; it’s a little bilobed structure simply posterior to the larynx. The thyroid secretes hormone that assist regulate metabolism.Trachea: the airway; it"s reinforced through rings of cartilage so the doesn"t collapse.Esophagus: tote food from mouth to stomach; soft and also muscular so it deserve to move a food bolus through peristalsis.

Thoracic cavity

Vertebrates have actually true coeloms. In mammals, the coelom is split into two key cavities: the thoracic cavity, which contains the lungs, and also the abdominal muscle cavity, which has the cradle system. The thoracic cavity and also the ab cavity room separated by the diaphragm. Keep in mind the countless membranes lining the coelom and also holding the organs in place.

Look for these frameworks in the thoracic cavity:

Lungs: they have actually several lobes. Keep in mind the just how spongy the organization is.Diaphragm: a paper of muscle and also connective tissue that help in breathing.

Abdominal cavity: digestion & absorption

Locate and understand the features of the complying with structures:

Liver: very big and dark. It has actually several lobes. You’ll need to lift it the end of the means to check out the offal beneath. The gall bladder is a little organ attached to the underside that the liver; it"s typically greenish because it includes bile.Stomach:Small & large intestineRectumStomach: might be surprise beneath the liver. Note the esophagus leading right into the stomach and the duodenum (first part of the little intestine) leading out. ~ passing through the large intestine, digested chyme goes come the rectum prior to being got rid of from the body.Mesenteries: thin, transparent sheets that connective tissue containing blood vessels connecting the intestine and also other organs. The mesenteries are folds of the peritoneum, i m sorry is the smooth, shining layer that lines the abdominal muscle cavity.Pancreas: white and looks a small bit prefer cauliflower. The secretes digestive enzymes and also buffers.

Abdominal cavity: various other organs

Locate and also understand the attributes of the following structures:

Spleen. The spleen is a level organ located near the stomach. That performs several functions related to producing and maturing brand-new blood cells and also eliminating old ones. Blood passes through open sinuses in the spleen, fairly than gift confined to narrow blood vessels.Urinary bladder & urethra. The urethra is the tube the carries urine from the urinary bladder come the urinary opening.Ovaries, uterus (females) or Testes (males). view the photos digital to find these. The size of the testes varies significantly, depending on the age of the fetal pig. The testes the males and also the ovaries of females both arise from the same embryonic structures; however, the testes migrate throughout fetal development until they descend right into the scrotal sac.

Circulatory system

Mammalian hearts have four chambers (see Campbell, p. 42.4). Each side of the heart has an atrium the receives blood from in other places in the body and also a ventricle that pumps the blood out of the heart. The ideal atrium receive blood native the systemic circulation and also passes it to the appropriate ventricle, i m sorry pumps the blood come the pulmonary circuit. ~ the blood passes v the lung it goes to the left atrium and then into the left ventricle, i m sorry pumps the blood right into the systemic circuit. The very first part that the systemic arterial circuit is the aorta, which shortly branches out to supply various regions the the body.

Fetal circulation is various from adult circulation. In the fetus, blood doesn’t gain oxygenated in the lungs; it it s okay oxygenated at the placenta. The umbilical arteries carry blood indigenous the fetus come the placenta. The umbilical vein carries blood indigenous the placenta earlier to the fetus. (Remember that in the placenta substances room exchanged in between fetal and also maternal blood, but the blood chin does no mix.) Therefore, the most highly oxygenated blood in the fetus is in the umbilical vein. Blood indigenous the umbilical vein gets combined with the rest of the systemic circulation and also returns to the best atrium. The blood entering the best atrium is the most oxygenated blood in the fetal heart, but it’s the least oxygenated blood in the adult heart. The fetus has two key tricks to it is adapted to this fact:

First, some of the blood that pipeline the appropriate ventricle bypasses the lungs. In one adult, this blood requirements to go to the lungs to obtain oxygenated, yet the fetus has actually a ductus arteriosus that short-circuits this blood flow, allowing some blood to go directly into the aorta and then right into the systemic circulation.

Second, in the fetal heart, there is one opening in between the right atrium and also the left atrium. This opened is referred to as the foramen ovale. The foramen ovale is beneficial in the fetus since it lets the oxygenated blood from the placenta obtain circulated faster. The circulation pattern is somewhat comparable to that of a frog (Campbell, p. 874). The foramen ovale generally closes up in ~ birth, maintaining blood circulation of the two sides that the heart completely separate. In some people, the foramen ovale does not close up. This condition, dubbed patent foramen ovale, can an outcome in serious health and wellness problems.

Here"s a diagram of circulation in a fetal pig:

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Image courtesy of OpenWetWare.

And here"s a diagram of person fetal circulation:

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Image by OpenStax college , via Wikimedia Commons.

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Sample test questions

You should be prepared to identify any kind of of the frameworks labeled top top the diagrams on this web page or provided in bold form in the text of this page. You can see either of the two specimens displayed on this page, or a dissected specimen favor the one you examined in lab.