Gr 11 Fetal Pig Dissection

Circulatory System

Figure 1 - Heart

Heart – a cardiac muscle that continuously pumps blood throughout the body. It is has tough tissue because it is a muscle that has to contract non-stop. It is divided up into four chambers:
            1. Right atrium        
            2. Right Ventricle
            3. Left Atrium           
            4. Left Ventricle      
1,2 - the right side of the heart receives blood from the veins and sends it to the lungs.
3,4 - the left side of the heart has more muscle because this is where the oxygenated blood from the lungs is pumped to the whole body.

Blood Vessels
            Artery –  a blood vessel that carries blood away from the heart. It is thick and more “rubbery” than a vein. This is to withstand the pressure of the blood being pumped to the body. The aorta (a) is the largest artery in the body.
            Vein – carries blood to the heart. It is thinner than a vein because it doesn’t go through too much pressure. 

Kidney – an organ that filters toxins out of the blood. This is the reason why it was so dense inside.

Digestive System

Mouth – the teeth begin physical digestion by breaking down food into small bits. The shape of the teeth depend on the main diet of the organism, The pig has both sharp incisors, canines and flat molars for an omnivorous diet. The saliva (amylase     enzyme) chemically breaks down the food into simple sugars.

Pharynx and Epiglottis – a hollow tube that leads into the trachea (or esophagus). The epiglottis is a flap that prevents food from getting into the trachea.

Esophagus - a soft tube that is connected to the stomach. It is made of muscle tissue that moves food along through peristalsis.

Figure 2 - Stomach Lining

Stomach - a sac-like organ full of liquid. I think it was the nutrients from its mother that was transported through the umbilical cord. The inner lining was slimy so there was mucus in it which suggested that there was also hydrochloric acid. The sphincter muscles were already developed to stop the acid from burning the esophagus and the small intestine.

Figure 3 - Small Intestine

Small Intestine – this was approximately 5 ft long. Inside the intestine were small very fine villi. They were there to increase the surface area which would also increase the amount of nutrients absorbed. The length of the intestine was all coiled up by connective tissue to prevent it from going all over the cavity.

Figure 4 - Large Intestine

Large Intestine – The large intestine's main role was to reabsorb water to the body. It was placed in a way that it was resting on top of the small intestine if the pig was standing up. This made it better for controlling the amount of waste that came out.





Rectum - This organ is a small sac found on the posterior side of the pig. It was still connected to the umbilical cord to release waste products through the mother.

Figure 5 - liver



Figure 6 - Gal Bladder behind liver

Liver and Gall Bladder - The liver was a large organ curved around the stomach. It was divided into Inside, it was dense because its function is to filter out toxins. The liver also created bile. The gall bladder, a small sac, was situated inside the liver to store the bile

Spleen – It was a sac about three inches long connected to the liver. It is a blood reservoir that holds blood until needed.



Respiratory System

Figure 7 - Nose and Mouth

Nose – A small cavity that has tiny hairs. It takes air and filters out unwanted dust from the air while moistening.

Pharynx and Epiglottis – a hollow tube that leads into the trachea (or esophagus). The epiglottis is a flap that prevents food from getting into the trachea.

Trachea – a tube held open by C-shaped cartilage that leads to the lungs. The cartilage is there so air can get in all the time.

Bronchi and Bronchioles – the bronchi branch out from the trachea, still with the C-shaped cartilage so that air can come in. The bronchi branch out further in the lungs as bronchioles and end as alveoli.

Figure 9 - Lungs

Lungs - dense organs that carry out gas exchange through the alveoli. The large surface area makes it easier to get more air into the blood stream.
            Alveoli – tiny air sacs in the lungs that carry out gas exchange.








How are the three systems interrelated?

Earthworm vs Fetal Pig

Homeostasis
 

Homeostasis is the term used to describe the body’s ability to adjust to the external and internal environment. Since the body is rarely given its ideal conditions, it needs to adjust itself to the conditions it’s given. This is done by special receptors that monitor different factors of the body. When the homeostasis is disrupted the monitor sends a signal to the brain where it works to adjust itself. Homeostasis affects all systems of the body. For example, when the digestive system puts too much sugar in the circulatory system, the pancreas creates insulin to level off the sugar levels.