Wednesday, September 26, 2012

Chapter 4: Tissues


Welcome back, students! This week we are going to go over the basics of Tissues in the human body! There are 4 main types of tissue; Epithelial, connective, muscle, and nerve. 

First, lets talk about Epithelial tissue. There are 3 types of Epithelial tissue; Cutaneous, mucus and serous. The cutaneous type is the tissue of your skin. The mucus tissue is the type of tissue that lines your viscera for example your digestive and respiratory track . Serous is the membrane sound in you ventral body cavity (remember the ventral body cavity is the cavities that house your organs). The main functions of the epithelial tissue is to supported by connective tissue, contains no blood vessels but supplied by nerve fibers, and regenerative. It is important that Epithelial tissue is regenerative because this function rapidly produces more skin cells if you ever get a cut or scrap. 

Second, Connective Tissue is the most abundant and widely distributed out of all the different types of tissue. There is proper connective tissue which is dense tissue and there is special tissue. The connective special tissue are the blood, cartilage, and bone tissue. The main functions of this tissue is support, protection, insulin and transportation. These special tissues have special cells chondroblasts for cartilage, osteoblasts for bones, and hematopoietic stem cells for blood. 

The muscle and nerve fiber are the least abundant type but that does not mean they arent important! Nervous tissue has branched neurons with long cellular process and support cells. Nervous tissue transmit electrical signals from sensory receptors and effectors (what we learned about a few blogs back!). Muscle tissue has two different types, skeletal and cardiac. The skeletal tissue is long with multiple nuclei. This particular tissue initiates and controls the voluntary movement in the body. The Cardiac muscle tissue is branchy with only one nucleus and also has interlocking discs that work as gap junctions. The function of the cardiac muscle tissue, as you may of guessed, pumps blood into the circulation. This type of tissue is found on the walls of the heart.

I hope this breakdown of the different types of tissues makes reading or rereading chapter 4 in the Human Anatomy and Physiology book!

Good Luck on your first semester exams!


Word Count: 375

Wednesday, September 19, 2012

Chapter 3: The Cell Cycle


This week, we are going to go into detail about the cell cycle (Mitosis) which is discussed in great detail in chapter 3! 

1. Interphase
    Cells in the human body are most of the time in this phase. This phase is when a cell is going through its normal routines and functions. This phase is not considered part of Mitosis. Genetic material in this phase is in the form of chromatin. The nucleus looks like its normal self here, the nucleus is visible (at least under a microscope). Even though the cell is going through its normal routine, the DNA is being replicated and preps for actual Mitosis.

  1. Prophase
    Prophase is a long stage and often divided into early and late prophase.
Early- Chromatin forms sister chromosomes attached by the centromere. Spindle fibers are starting to be formed. 
Late- In late prophase, the nuclear envelope starts to break up and the spindle fibers that were formed earlier in prophase start to attach to the chromosomes. Also, the centrioles are heading to opposite polls of the cell.

When you look under the microscope at prophase, you can tell it apart because the nucleus looks like it has several holes in it. Also, sometimes the chromosomes look like little squiggles in the inside of the cell.

  1. Metaphase
   In metaphase, the centrioles are at their opposite ends of the cell and the chromosomes are lined up on the metaphase plate. (That is easy to remember, during metaphase chromosomes are lined in the center of the cell on something that looks like an equator). In looking at this stage under a microscope, you can see the sister chromosomes all lined up in the center of the cell, for me, metaphase is the easiest phase to point out under a microscope because it is the most unique.

  1. Anaphase
    In this stage, the centromeres of the sister chromosomes are pulled apart simultaneously and you can see chromosomes being pulled to opposite sides of the cells from the spindle fibers toward opposite centrioles. 

  1. Telophase
    When the chromosomes are stopped moving is when telophase starts. It helps me to think of telophase as the opposite of prophase. Here, the chromosomes condense and turn back into chromatin. The nuclear envelope starts to reform around the chromosomes. Telophase is hard for me to point out in the microscope because it looks similar to other phases. It helps me to look for a cleavage furrow, it looks like siamese twin cells, they are still connected but you can still see the 2 separate  cells. 

  1. Cytokinesis
   Mitosis ends with the split of the cytoplasm to form 2 identical cells

I hope this breakdown of the cell cycle helps you remember certain phases and also help you during lab practical!


Word count: 437

Wednesday, September 12, 2012

Chapter 2: Part 2


       The second part of the chapter continues to go into depth on chemistry. There are several other key aspects of chemistry that are important when learning about anatomy and physiology. First, let us go over what polar and nonpolar covalent bonds mean. Nonpolar covalent bonds have electrons that are shared equally.  This produces electron balance, which means that no side of the molecule is charged. An example of a nonpolar molecule is CO2. Polar covalent bonds are when the electrons are shared unequally, which means the atoms in the bond can have different charges. This creates something called a dipole. A dipole means one side of the molecules electronegative and the other side is electropositive.  An example of a polar molecule is water, H2O. Polar and nonpolar molecules are important in anatomy and physiology when learning about different parts of the cell.
      A great example of how polar and nonpolar molecules work is the cell membrane. When looking at a cell membrane up close it has a bilayer, two layer, and membrane. This membrane is made up of phospholipids which have a polar and nonpolar side.  The inside of the bilayer is nonpolar and the outsides are polar. This is important for the cell because it allows cells to work well with water in the cell and outside of the cell. Molecules need to pass through the cell membrane in order to feed the cell and also get things out of the cell.


The second thing I am going to discuss is different reactions.


Synthesis Reactions           A+B-àAB
  • ·         Taking small molecules and making them big
  • ·         anabolic reaction
  • ·         always involved bond formation


Decomposition reactions   ABà A+B
  • ·         breaking down a molecule into smaller molecules
  • ·         catabolic reaction
  • ·         reverse of synthesis


Exchange reactions           AB+ CàAC + B
  • ·         AKA displacement reaction
  • ·         Involving both synthesis and decomposition
  • ·         Example: ATP transfers its terminal phosphate group to glucose

Oxidation reactions
  • ·         AKA Redox reactions
  • ·         Food fuels are broke down for energy
  • ·         Involve exchange reaction between reactants
  • ·         If the products added a Hydrogen is it called a Reduction
  • ·         If the products gave a Hydrogen it is oxidize
     A mnemonic device I use to remember which reaction is reduction or oxidation is
           LEO SAYS GER
    Lose an electron= oxidized
    Gain an electron= Reduction


Tune in next week for Chapter 3 review!

word count: 362







Wednesday, September 5, 2012

Chapter 2: Basic Chemistry (Part 1)


Chapter 2 in the Human Anatomy & Physiology is all about chemistry! This isn’t always everybody’s favorite topic so I am going to break down the chapter into 2 blogs because it has A LOT of information! Hopefully this post helps break down the basics of chemistry and is helpful for studying!

First, let’s go over the definition of matter. The authors define matter as anything that has mass and occupies space. Matter can be found in 3 different states, solid, liquid, and gas. All matter is composed of elements, substances that can’t be broken down into simpler substances, and these elements have different chemical and physical properties. Atoms, which make up elements, are what give these elements their physical and chemical properties. It helps me to look at the periodic table when discussing elements because it has pretty much everything you need to know about them right on the table!

periodic_table.gif





As you can see, the diagram shows you a few different parts. The element symbol is the abbreviation of the element name, which for this diagram is C.  The atomic number of carbon is 6. The atomic number of an element is the number of protons the element has in the nucleus. This is important for finding out how many electrons and neutrons there are in an element! Lastly, the atomic weight of the element is located usually on the under the element name. The atomic weight is the average mass of the element.

Now that we’ve gone over a little about the different parts of the periodic table, I want to discuss a little about the different types of chemical bonds. An Ionic bond is when atoms gain or lose electrons and comes charged, but the number of protons remains the same. A covalent bond is the sharing of 2 or more valence shell electrons; this allows each atom to fill its valence shell. Lastly, hydrogen bonds are an attractive bond or force between an electropositive hydrogen and another electronegative atom from another molecule. Remember about hydrogen bonds is that they are not a true bond!


I hope this basic overview of chemistry from the first part of chapter 2 is helpful! Check back next week for chapter 2: part 2!



Word Count: 371