Unit 10 Reflection

Unit 10, the final unit of the year, was about physiology. We learned about the different organs and organ systems in the body, including the digestive system, circulatory and respiratory systems, immune system, lymph system, endocrine system, and nervous system.

The digestive system is responsible for breaking down food and absorbing the vitamins, minerals, fats, proteins, and carbohydrates. In the mouth, food is broken into smaller pieces, and the digestion of carbohydrates begins. Then food is swallowed, and is moved to the stomach in a process called peristalsis. While people usually think of the stomach when thinking of digestion, most of the digestion occurs in the first part of the small intestine called the duodenum. The small intestine is also where absorption occurs. The intestines are covered in small structures called villi, which absorb nutrients. The lining of the small intestine is folded to increase surface area and maximize the amount of villi. The villi are covered in microvilli, which also absorb nutrients. The large intestine absorbs water and gets rid of solid waste. Your digestive system is full of bacteria, which help to digest food and ferment indigestible food.

The duodenum

The nervous system is what sends signals all over your body. The two different parts of the nervous system are the central nervous system (CNS) and peripheral nervous system (PNS). The central nervous system is made of your brain and spine, and the peripheral nervous system is made of the nerves that spread throughout your body. There are four different parts of the brain. The cerebrum controls thoughts, movement, and emotion. The deincephalon works with the endocrine system and sends information to the cerebrum. The cerebellum  controls subconscious thoughts, determines body position, and calculates force of muscle movements. The spinal cord receives impulses from sensory neurons and sends signals to motor neurons. Neurons are specialized cells for sending and receiving signals. Sensory neurons carry signals from sensory organs like eyes, ears, and nose. Internuerons carry information from sensory neurons to motor neurons. Motor neurons send signals from the CNS to muscles and glands.

The endocrine system is like the nervous system, because it is used to send signals to other parts of the body, but the endocrine system does it more slowly and has longer lasting signals. Different glands in the body release hormones into the bloodstream, which cause changes to certain cells in the body. Some of the important glands are the hypothalamus gland, which links the pituitary gland and the nervous system. The pituitary gland controls the other glands. The thyroid gland absorbs iodine and regulates growth. On the thyroid gland are the parathyroids, which regulate calcium levels. The adrenal gland releases epinephrine, which controls the "fight or flight" response. The pancreas releases both insulin and glucagon to control blood sugar levels.

The circulatory and respiratory systems work together to bring oxygen to all the cells in the body so that they can perform cellular respiration and create energy in the form of ATP for the body. The diaphragm is the muscle that causes the lungs to expand and contract, which controls breathing. The oxygen inhaled diffuses into the bloodstream at the alveoli, and carbon dioxide also diffuses out of the bloodstream to be exhaled. Oxygenated blood flows through arteries, and when it is low in oxygen it flows through veins. Blood flows through the body, and then returns to the heart through two veins, the superior and inferior vena cava. Blood goes from the right atrium to the right ventricle, and then goes through the pulmonary artery to the lungs where it gets oxygen. The blood comes back in the pulmonary vein to the left atrium, then it goes to the left ventricle, and leaves for the rest of the body in the aorta.

The alveoli, where oxygen and carbon dioxide diffuse in and out of the capillaries

The next system we learned about is the immune system. The immune system has two methods to fight off pathogens, innate immunity and adaptive immunity. Innate immunity is a general defense that doesn't target any specific pathogen. The first part of this defense is the skin on the outside of out body, mucous membranes, and the acidity of certain parts of out bodies. After that come the internal defenses, such as phagocytes, which eat pathogens. Another type of cell is the natural killer cell. They kill pathogens or infected cells. After these defenses is the adaptive immunity. T and B cells are created with different antigens on them. If a certain antigen matches and kills the pathogen, copies of that cell are created to prevent getting infected by the same pathogen twice.

The final system we learned about is the lymph system, and inflammatory response. The lymph system collects waste and blood from tissues all over the body. The lymph nodes also create white blood cells when you get sick. The inflammatory response is how a body responds to pathogens, and is part of the innate immunity. The different types of inflammation are acute inflammation, which occurs at a single spot where a pathogen is, and systemic inflammation, which occurs throughout the whole body. In the small intestine, if things other than digested food get through the intestinal wall, it can cause systemic inflammation. Chronic systemic inflammation is when the body is constantly doing systemic inflammation, and makes it harder for the immune system to do its job.

Overall, this unit was easy to understand, and probably one of my favorites. If at all, I'll spend most of my time reviewing the lymph and endocrine systems. Other than that, I understand all the organs we learned about.

I'm sorry to disappoint the two people who actually read this blog, but this is going to be my final post, because the school year is about to come to a close. If this is your first time reading this blog, check out my best work here and here. I'm glad I got the chance to share my work with anyone who had to learn the same stuff, or who was just interested in it, and I hope enjoyed reading it.

20 Time Final Post

Well, 20% of my time in biology has come and gone, and a few days ago, we did this presentation you see here (I'm on the left). We encountered many difficulties, such as calculating radiation. Our final product was meant to be an infograph, but we ran short on time and didn't finish. If you want to see the unfinished infograph, check here. The fact that it is unfinished isn't important, what's important was what we accomplished. Overall, I believe we did very well on our presentation. We were both nervous, and stuttered a bit, but with the little rehearsal we got, we did a lot better than I thought we would. Our preparation was limited because we were unable to get together before the presentation. This was a great project that gave us an opportunity to learn what we wanted, and I just wish we had more time to work on it. If you want to see what my partner said about this project, check out his post here.

Unit 9 Reflection

Unit 9 was about taxonomy, and focused on the different domains and kingdoms, and some important phyla, mostly in the domain Eukarya.

Taxonomy is naming and classifying organisms. Organisms are named Genus species, with the first word capitalized and the second lowercase. The different levels of taxonomy (from largest to smallest) are domain, kingdom, phylum, class, order, family, genus, then species. The three major domains are Archaea, Bacteria, and Eukarya. The different kingdoms in the domain Eukarya are Protista, Fungi, Plantae, and Animalia.

Bacteria are prokaryotic unicellular organisms that come in rods, cones, and spirals. The cell walls contain peptidoglycan, which can be detected in a gram stain. Bacteria have flagella which help them move. Chemoheterotrophs take in organic molecules. Photoautotrophs do photosynthesis. Chemoautotrophs use energy from chemical reactions for energy. Obligate Aerobes need oxygen to survive. Obligate Anaerobes can't survive with oxygen. Facultative Anaerobes can survive with and without oxygen.

Fungi, which aren't plants, are multi-cellular, except for yeasts. Hyphae are long strands of fungi, and mycellium are underground hyphae. Sac fungi have a reproductive sac. Yeast fungi are single celled sac fungi. Club fungi have club shaped bodies. They can reproduce sexually, asexually, or both.

An example of Club Fungi

Plants first grew at the edge of water, and eventually were able to grow away from water. Some plants have a vascular system, meaning they can move resources throughout them. Some plant phyla include Bryophyta, which are non vascular, seedless plants, like moss. Pterophyta are seedless, vascular plants. Gymnosperms use cones to reproduce. Cycads look like palm trees, Ginkgo have only one remaining species, and conifers are the most common plant. Angiosperms are flowering plants, and produce seeds in fruit. An angiosperm can be a monocot, meaning it has a single seed leaf, or dicot, meaning it has a double seed leaf.

Invertebrates in the animal kingdom don't have vertebrates. Sponges, which are invertebrates, are the most primitive animals. Some phyla of invertebrates are Cnidarians, which have stinging cells, and two body forms, which are the Medusa and the Polyp. The classes of Cnidarians are Scyphozoans, Anthozoans, Hydrozoans, and Cubozoans. The phylum of Flatworms contains parasitic organisms with an incomplete digestive system. Molluska have a complete digestive tract, and either radula for feeding, a mantle, or a ctenidia, which is a respiratory system. Annelida are worms that have a segmented body, such as earthworms, marine worms, and leeches. Arthropods are some of the most diverse animals. They have an exoskeleton, jointed apendeges, segmented body pars, sensory organs, and an open circulatory system. Crustacea have two body sections, antennae, an exoskeleton, and a carapace, which is a hard outer shell. Echinoderms have an internal skeleton, a complete digestive system, and some can regenerate limbs. They also have a water vascular system, which uses water pressure to move.

Example of an Annelid

Vertebrates, or chordates, unlike invertebrates, do have backbones. There are seven classes of vertebrates. Agnatha were the first vertebrates, and the two remaining groups are lampreys and hagfish. Chondricthyes have cartilage skeletons, have jaws, and must move to breathe. Osteichtyes are have bone skeletons, and also have jaws. An important type of fish is the lobe finned fish. This fish evolved into all tetrapods. You can learn more about this fish in the presentation I did in my class. Amphibians are tetrapods that live both on land and in water. They also go through metamorphosis, such as tadpoles turning into frogs. Reptiles are ectotherms, which means that their body temperature is determined by the environment. Class aves, which are birds, have hollow bones. Finally, class mammalia are large brained endotherms, which means their temperature isn't controlled by the environment. They have hair mammary glands, and sensitive ears.

Overall, this is probably the hardest unit so far, just because of the massive amount of content covered in it. I will continue to study, and hopefully be able to remember every phylum.

My Inner Fish

We just finished watching the series, "Your Inner Fish." The series discussed the different features of modern mammals that came from fish and reptiles, and how the benefited us, such as hair, skin, bone structure, and hearing. There were many fossils that showed how certain features transitioned from reptile or fish to mammals, and there are some species that still show some of these transitions alive today. Like we learned in class, natural selection chooses the best traits to be passed down, and possibly create a new species. Two of the most important questions we were asked were, "Why are mass extinctions important?" and, "Why is the series called 'Your Inner Fish'?" Mass extinctions are extremely important. They cause many species to go extinct, which allows the surviving species to take their place, and allows new organisms to evolve. Without them, we wouldn't be here today. The name of the series may not seem as important, but it explains a lot. Because we have all evolved from fish, this helps to reveal that we have many similar traits with fish, but because of evolution and natural selection, we have become a whole new species.

Diagrams of different embryos showing how some of the similarities  between humans and fish