SPRING 2005
These are areas where the class as a whole was weak. Please try to fix these before the final!!

EXAM 1:
    Why are we studying all about atoms and chemical bonds? Because it is in chemical bonds that the body stores energy!! Remember that a molecule of carbohydrate or fat contains a lot of potential energy. To release this energy we break the chemical bonds and capture the energy that is released (we will find out how this is done when we talk about cellular respiration.)
    A protein's function depends on its structure. The primary structure of a protein is the order of the amino acids in the peptide chain. The secondary structure occurs when areas of the protein fold into helices or pleated sheets, and the tertiary (third level) structure comes from the three-dimensional folding of the protein. It is this last structure that is lost when the protein denatures. Some proteins also have a fourth level or quaternary structure if several peptide chains come together to form the final protein (as happens in hemoglobin- the oxygen carrying protein found in red blood cells.)
    Remember: Steroids are all made from cholesterol. These are all lipids. Why is this going to be important? Remember that the cell membrane is made of (phospho-) lipids. Steroids and other lipids can simply pass through this membrane to enter a cell. This will influence how they work inside the cell. It also means that they can be taken orally instead of needing to be injected (like the protein hormone insulin.)
    Unsaturated fatty acids contain one or more double (covalent )bonds (mono- and poly- unsaturated fatty acids, respectively). Saturated fatty acids contain only singe covalent bonds, (with the exception of the oxygen carbon double bond in the acid part) and therefore contain the maximum number of hydrogen atoms possible ( the idea of "saturation" with hydrogens.)
    Membrane proteins control nearly everything that enters and leaves a cell because they form the channels that allow specific substances to enter or leave the cell, and they form the transporter that carry specific substances across the membrane. In addition, they can be receptors for hormones, enzymes that control what happens in the cell, cell identity markers, and function in holding cells together (desmosomes, for example) and allow cells to communicate (gap junctions for example.) The only thing they don't do is make up most of the cell membrane - that is phospholipid!!!
    Remember, because we will be talking about this again, that the DNA is copied (synthesized, replicated, duplicated) during the S phase of interphase. This has to happen before the cell can start to divide, so it could not happen during any of the steps of mitosis or meiosis.

EXAM 2:
    Don't forget that amino acids make up peptides and proteins, simple sugars or monosaccharides make up complex sugars or polysaccharides, glycerol and fatty acids make up neutral fats or triglycerides, and nucleotides make up nucleic acids -DNA and RNA.
    Remember that enzymes are proteins  whose names end in -ase, and that speed up reactions but are not used up in these reactions. Vitamins tend to be co-factors or co-enzymes, so they are necessary for vital reactions to take place, but because they can be used over and over, we don't need large amounts of them.
    The products of the Citric Acid or Krebs Cycle are carbon dioxide, NADH, FADH₂, and a small amount of ATP (which is made from GTP produced by the cycle.)
    When DNA is transcribed to RNA  U is substituted for T. So a sequence of DNA that read: ATCGCGTA would have a complimentary RNA sequence that read UAGCGCAU.
    The term Intron stands for "intervening sequence" i.e. "junk DNA" The introns are removed before the Exons or "expressed sequences" are put back together to form mature messenger RNA.
   Translation takes place on ribosomes, often associated with the rough endoplasmic reticulum, and Translation takes place in the nucleus (where the DNA is).
    Certain tissues can be identified with certain basic functions:
        Simple squamous epithelium is very thin and allows for diffusion to take place across it. It is also good for filtration.
        Stratified squamous epithelium, because of the multiple layers which can be rubbed off, it excellent for protecting delicate underlying tissues from abrasion. Therefore, we find it in places such as the mouth, esophagus, rectum and vagina.
        Dense regular connective tissue is good for resisting stretching in one direction, and makes good tendons and ligaments.
        Dense irregular connective tissue resists stretching in all directions, and is good for wrapping and lining bones and muscles.
    Connective tissue has several general characteristics, the most distinctive is that it has cells suspended in a matrix made up of fibers and ground substance. The ground substance can be liquid, semi-solid, gelatinous or very hard and determines the characteristics of that tissue. It has a lot of nerves and blood vessels (usually). With the exception of joint surfaces, it is NOT found on the surface of the body or lining cavities (that is the job of epithelial tissue.)
    The tissue that is found at the end of bones, in the rings of the trachea, and between the ribs and the sternum is hyaline cartilage - that is that nice white, shiny stuff you see at the end of chicken bones for example.
    Smooth muscle looks different from skeletal and cardiac muscle under the microscope- we cannot not see the stripes or striations that are found in the other two; and this is because the proteins that cause the muscle to contract are arranged differently in smooth muscle.  It non-voluntary, which means we don't have to think about moving food through our intestines, for example.
    Reticular connective tissue is that tissue that holds organs together, especially organs that contain a lot of loose cells, like our spleen and lymph nodes.
    Review the 5 layers of the epidermis:
        The stratum basale or stratum germinativum is a single layer of cells that undergo mitosis and produce all of the more superficial layers of the epidermis. Melanocytes are also found here.
        The stratum spinosum is called that because "spines" or the cytoskeleton of the cells show up on staining for microscopy. Cells take in melanin here by "cytocrine secretion".
        The stratum granulosum is made up of several layers; the cells contain granules of a substance that will be keratin.
        The stratum lucidum is the clear layer which is more visible in the thick skin of our palms and soles than in other skin layers.
        The outermost layer is the stratum corneum "horny layer", where the cells are flat, filled with keratin, and dead.
       
   
EXAM 3:
    Folks! You have been looking at the microscopic structure of bone since the tissue chapter in lecture and in lab!!! The hole in the center of the osteon is the central canal ( where we find blood vessels and nerves), the layers or rings are the lamellae, the osteocytes are found in spaces called lacunae (lakes), and are connected to the central canal by canaliculi (little canals).
    When you look at a joint, such as the elbow, don't stop at the obvious! The articulation between the ulna and the humerus is a hinge joint, between the radius and ulna is a pivot joint (allowing Supination of the hand), and between the radius and the humerus is a gliding joint.
    The medial side of the knee is strengthened by the tibial or medial collateral ligament, the front of the knee joint is strengthened by the patellar ligament and tendon, and the lateral side of the knee is strengthened by the fibular collateral ligament; the back by the arcuate and oblique politeal ligaments.
    Please review the physiology of muscle contraction! Acetylcholine is released from the motor neuron. The ACh diffuses across the synaptic cleft and binds with receptors on the motor end plate. The binding of ACh to the receptors opens channels in the sarcolemma that allow sodium ions to rush into the cell. The inflow of sodium ions causes a muscle action potential to spread over the sarcolemma and down into the T-tubules. This electrical current flowing down the T-tubules causes the sarcoplasmic reticulum to release calcium ions into the sarcoplasm (not out of the cell). Calcium ions then bind with troponin, which changes shape, pulling on the tropomyosin, and exposing the binding sites on the actin. The myosin heads, which were charged with ATP, bind to the actin and pull (power stroke), causing the thick and thin filaments to slide past each other, and the sarcomere to shorten.
    To relax the muscle, the first thing we have to do is to remove ACh. This is done by the enzyme acetylcholinesterase, which is located in the synaptic cleft and breaks ACh down into acetic acid and choline.
Creatine phosphate is a special energy storing molecule in muscle cells. While it CANNOT POWER REACTIONS DIRECTLY, it can transfer a phosphate group to ADP to make ATP which can supply energy for muscle contraction.
    Glycolysis is fast (many fewer reactions than all of cellular respiration), anaerobic (doesn't use oxygen) and inefficient (produces only 2 molecules of ATP for each molecule of glucose as opposed to the 32-36 molecules of ATP produced by cellular respiration).
    Cardiac muscle and smooth muscle can both have gap junctions uniting the muscle fibers. These are not present in voluntary or skeletal muscle cells.
    Cardiac and Skeletal muscle cells have T-tubules, but there are no T-tubules in smooth muscle fibers.
    Remember that cardiac and smooth muscle cells get most or all of their calcium from outside the cells, from the interstitial fluid. It diffuses in; it is NOT brought in by active transport.
    If a muscle fiber has a lot of myoglobin and capillaries, as oxidative fibers do, they will appear red. If the fibers are glycolytic, they will have fewer capillaries and more glycogen and will appear white.
    An aponeurosis is a broad, flat sheet-like tendon, like the one found on top of your head connecting the frontalis muscle with the occipitalis muscle.
    Review the picture of the generalized synovial joint, figure 8.7 on page 257 in your textbook. Be sure you can locate the periostium, spongy bone, articular cartilage, synovial or joint cavity, synovial membrane and joint or articular capsule. (Remember that on an exam I can't give you color, so memorize shape and location!!!!)

EXAM 4:
    Please be sure you know the effects of the sympathetic vs. the parasympathetic nervous system. A lot of you are still getting these two confused.
    Refer to the chart in the PowerPoint presentation to help you remember that light, chemical and mechanical gated channels give graded potentials - the response is proportional to the stimulus (look over the other characteristics as well!). Only voltage gated channels give us an all-or-none response.
    PLEASE remember sodium is more concentrated on the outside of the axon and moves INTO the axon during depolarization. Potassium is more concentrated INSIDE the cell and moves out to repolarize the  axon.
    Calcium is important in the release of the neurotransmitters. When the action potential reaches the synaptic end bulbs it opens calcium channels and allows calcium to flow into the axon terminals. This triggers a chain of reactions that causes the axon to release the neurotransmitter in its vessicles by exocytosis.
    Remember that the sympathetic postganglionic neurons release norepinephrine, a catecholamine, and the postganglionic neurons of the parasympathetic nervous system release acetylcholine.
    Neurotransmitters can be broken down in the synaptic cleft ( remember acetlycholinesterase?); can diffuse out of the synaptic cleft; or may be taken back up into the neuron that released them.
    The ventricles of the brain: the first two are located deep within the cerebral hemispheres, the third surrounds the isthmus of the thalamus, and the fourth is located between the cerebellum and the medulla oblongata.
    The peripheral nerves that enter the dorsal root are sensory, and the motor neurons leave the spinal cord through the ventral roots.
    Look over the spinal cord and know where to find the cervical enlargement, the lumbar enlargement ( why are these here?) and the conus medularis and cauda equina. Know that extensions of the pia mater, called the filum terminale and the denticulate ligaments, hold the spinal cord in place within the vertebral column.
    Know that the sensory or somatosensory cortex is located in the postcentral gyrus and the motor cortex is located in the precentral gyrus.
    The amount of cortex devoted to a particular area of the body depends on the number of motor units that go to that area ( so areas like the face and the larynx and hand get more space - more motor units than the back or legs) or the number of sensory neurons in that area.
    The left side of your brain is the logical side, and the right is the artistic/imaginative side.
    Remember that within the spinal cord fibers of a single  type (sensory or motor) travel together in bundles called tracts that are NOT separated from each other by connective tissue.
    Be sure that you know what the thalamus, hypothalamus, reticular activating system, cerebellum, limbic system, pons, superior and inferior colliculi, mammillary bodies, and medulla oblongata do in the brain.
    The connective tissue layers that surround and penetrate nerves are nearly identical to those we talked about with muscles epi-, peri- and endo- but these end in neurium instead of mysium.
    The cell bodies of the neurons associated with the autonomic system are found in the lateral gray horns of the spinal cord. (or nuclei in the brain in the case of cranial nerves).
    Review the comparison chart for the sympathetic and parasympathetic nervous system.