Body Systems

By Marla Kennedy

Skeletal System

Skeletal system of a prawn

The prawn has a shell that is fragile and can snap easily, though some parts are bendy. It protects their insides from getting damaged. Lobsters, crayfish, yabbies, crabs, shrimp, barnacles or any other types of crustaceans have this skeletal system. The difference between our skeleton and theirs’ is that we have an endoskeleton that contains bones, while theirs is more of a brittle shell. A benefit is that it is more bendy and flexible, it can allow plenty of movement. When the prawn grows, it sheds its original shell and grows a new one. This could also be a disadvantage and are often vulnerable during this process. Their kind of skeletal system is an exoskeleton made of chiton which is a type of sugar and calcium carbonate for strength.

Skeletal system of a worm

The worm has a hydroskeleton. They are able to move around by stretching and contracting to take the next step.

Skeletal system of a cuttlefish

The cuttlebone is fragile and crumbly. It’s also light, which would benefit for floating and swimming around the water. The main role would be supporting the fish and its movements. They have an endoskeleton made of aragonite providing buoyance.

Skeletal system of humans

The structure of our skeleton is endoskeleton made up of hard bones and a softer connective tissue called cartilage. Its role is to support and hold us up. It also protects the organs and allows movement and elasticity. The bone marrow is found in the inner structure of the bone. This is where red blood cells and platelets are made. Our bones are made of living cells surrounded by calcium phosphate, making it hard, collagen, producing elasticity, and blood vessels, providing essential nutrients. All mammals, birds and reptiles also share this skeletal system.

Skeletal systems prac

Muscular system

Chicken wing dissection

The chicken wing is equivalent to the upper arm of a human. When you tug on the muscles in the upper wing, they are stretching and contracting allowing the wings to move. These correspond to the bicep and tricep in humans. The bicep is the flexor muscle causing the limb to flex when contracting, and the tricep is an extensor, causing the limb to extend when it contracts. When you tug on the muscles in the lower wing, they are also stretching and contracting, allowing the lower wing to bend and flex.

The tissue that connects the muscle to the bone is called the tendon. They are these milky white strips that are thin, but are strongly attached. The tissue that connects the bones at the elbow joint is called cartilage. The elbow joint is an example of a hinge joint, while the joint that connects the wing at the shoulder is called a ball and socket joint. The cartilage that was there was a smooth, shiny, creamy white. There was only a light layer on the end of the bone. The bones we found in the chicken wing were the humerous, the ulna and the radius.

Skeletal and Muscular systems comparison

The skeletal and muscular systems work together in that they help the body to move. A tendon, a type of tissue, attaches muscles to bones. We tried moving the wings up and down in the chicken wing dissection, once we pulled on a string of ligament, the joints moved up and down flexing and extending the bicep and tricep. When we tugged on the muscles, the tendons attached to the bones moved the bones up and down. Voluntary muscles, also known as skeletal muscles make up 50% of body mass. These muscles move and support the skeleton.

The heart and circulatory system

Heart dissection

The flesh of the heart is a dark red/purple colour, with a decent layer of fat mostly covering the top of the heart. There are lots of deep creases with the outside smooth, some parts being more flexible than the other more muscular parts. The coronary arteries carry nutrients and oxygen to the heart muscle. They are thin and dark red. Most of them were vertical, breaking off in different directions. If this artery was blocked by a clot, you would have a heart attack or angina. In terms of the left and right side of the heart, you can tell this by looking at the top of the heart, to where the vena cava, aorta and pulmonary artery.

The thicknesses of the muscles at the top of the heart are thinner than the muscles at the bottom, as the ventricles needs to be thicker and bulkier to carry the oxygenated and deoxygenated blood. The fats mainly cover the top of the heart and around the veins. The aorta is the largest and most muscular. The vena cave and pulmonary artery are similar sized on either sides of the heart.

Deoxygenated blood leaves the right ventricle in a vein and travels to the lungs. Here, the blood collects oxygen so it is now oxygenated. The blood travels to the heart via an artery. The aorta is the largest artery in the heart. It needs to be thick in order to pass the pumped blood to the rest of the body. The vena cava is a little smaller as its only job is to pass deoxygenated blood onto the lungs, it goes back into the right atrium.

When the water flowed through the heart, it went into the vena cava and came out of the pulmonary artery. When the water was flowing in the pulmonary vein, it came out of the aorta. Inside the left ventricle were the muscular walls and valves. The job of the valves is to stop back flow into the heart and ensure the blood goes in one direction. The aorta felt thick, hard and muscular.

box diagram

Walking the heart

This activity showed us the pathway of oxygenated and deoxygenated blood around the body on a much larger scale. Re-enacting the blood, we started at the lungs, being oxygenated, and made our way through the pulmonary artery and into the left atrium. we then passed some valves going into the left ventricle and back out the aorta to the body. Once we had changed from oxygenated to deoxygenated blood, we followed through the vena cava into the right atrium, then into the right ventricle, and back out to the lungs.

Pluck prac

The trachea was quite slippery on the outside, but tough on the inside, this was because of the cartilage. The cartilage supports the trachea so it doesn’t collapse in the body. The lungs were a light colour, and became lighter as it inflated, also making the veins more visible. If the animal was alive, and the organs were full of blood, they would be a darker shade of red. The heart and lungs are connected by the capillaries, which branch out into the pulmonary artery and veins. The diaphragm contracts when we breathe in, to allow more air in the lungs, and relaxes when we breathe out. The liver took up a lot of surface area in the pluck. It was a dark purple- brown colour, and was a similar texture to the other organs in the body. The liver produces bile and gets rid of toxins in the body.

Circulatory and respiratory systems comparison

The circulatory and respiratory systems are linked to exchange oxygenated and deoxygenated gasses in the body. The tiny particles of gas are easily passed through the cell walls of the capillaries, these help with the gas exchange and are also where the two systems meet. The air we breathe in is oxygen, which is then collected in the lungs, passed through the alveoli and capillaries, and moved into the blood to be pumped into the body by the heart. Carbon dioxide moves through the pulmonary artery and is breathed out as a waste product.

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