Here are some areas that a large percentage of the class missed. You may see these again on the Final (or about the cardiovascular system on the next exam!!)

EXAM 1
    Remember that sensation occur when the information carried from the receptors reaches and is interpreted by the cerebral cortex. Also remember that the reason we interpret some sensations as sound and others as light or smells is due to the area of the brain where those neurons end up. Certain parts of our brain are programmed to interpret sights and sounds, etc. When a neuron ends up in the wrong area, we can get synesthesia - tasting colors, hearing smells, etc.
    The senses of taste and smell work together to produce the sense of taste. Both are chemoreceptors that require the chemicals to be dissolved in saliva or mucus before they will stimulate the receptor. The receptors, however, are very different! The receptor cells for taste are epithelial tissue, just like the rest of the taste bud, but the receptors for smell are bipolar neurons! These are extremely unusual because they are replaced throughout life, unlike most neurons in the body. But because they are exposed to the outside of the body, they experience more "wear and tear" and are replaced throughout life, though not completely (each year we lose about 1 % of those neurons.)
    The three bones or ossicles of the middle ear are there to transmit and amplify sounds within the ear. These are the malleus, the incus and the stapes.
    Cataracts occurs when the proteins of the lens of the eye become yellow and opaque. We can remove the old lens and replace it with a plastic one during cataract surgery. Cataracts have nothing to do (directly) with the cornea or the retina!
    Accommodation is our ability to change the shape of the lens in our eye so that we can see objects up close. To do this, we need to make the lens of our eye stronger (fatter). The suspensory ligaments (zonules of Zinn) attach the muscle of the ciliary body to the edges of the capsule of the lens. Remember that the ciliary muscle is a circular muscle. When it is relaxed, the diameter of the muscle is large, and it pulls on the edges of the lens, making it thinner. This is the eye at rest. When the ciliary muscle contracts, the diameter of the muscle gets smaller, releasing tension on the lens, which gets fatter. (remember the balloon demonstration)
    So many things about the eye are backwards. The way it works is one of them. In the dark, there is a substance called cyclic-GMP which holds the sodium channels open. So, in the dark, the sodium is constantly rushing into the cell (the "dark current") and causing the release of an inhibitory neuron transmitter that prevents the next neuron in line from firing. When light strikes the receptor, it changes the shape of the retinal molecule, which separates from the opsin molecule. The opsin then acts as an enzyme to break down cyclic-GMP, which closes the sodium channels and stops the release of the inhibitory neurotransmitter, allowing the next neuron in the pathway to fire, and tell our brains that we see something!
    When you are  emmetropic, or have perfect vision, your cornea, lens and the length of your eye all work together to focus the light directly onto the retina. When you are far-sighted or hyperopic, the components of your eye don't match properly, and the light focuses behind your retina. Fortunately, when you are young, you can bring your ability to accommodate into play, and focus your eyes to see clearly at distance (of course you have to work even harder to see things up close.) When you are myopic, or near-sighted, the light focuses in front of your retina because your eye is too long or the cornea or lens are too strong. There is nothing you can do (short of corrective lenses) to make the image clear.
    Look over the table in your book that identifies the function for all the white blood cells. We will be talking a lot about lymphocytes (Bcells and Tcells in the near future!)
    Review blood coagulation. The intrinsic and extrinsic pathway both have the same end product: prothrombin activator (or prothrombinase). Prothrombin activator converts prothrombin into thrombin, and thrombin converts fibinogen into fibrin. Many of the steps of coagulation require the presence of CALCIUM (Ca++), and we can prevent blood from clotting in a test tube by adding a chelating agent such as EDTA which ties up calcium.
    Vitamin K is required by the liver to produce clotting factors, and is sometimes given before surgery (several days or more) to be sure the person will be able to clot properly. 
    To dissolve or remove a clot you certainly don't want to give something that causes clotting! What you do give is tissue plasminogen activator, or t-PA. Whenever a clot is formed the inactive protein plasminogen is incorporated into the clot. When activated to plasmin, it digests or breaks down fibrin ( so it is also called fibrinolysin) and breaks up the clot.
    Blood flows from the right atrium into the right ventricle through the tricuspid valve. REVIEW THE LOCATION OF ALL THE HEART VALVES!
    The outer layer of the wall of the heart is the visceral pericardium, also known as the epicardium.
    The sinoatrial or SA node is the pacemaker of the heart. The impulse starts here, spreads through the atria, is stopped by the fibrous skeleton of the heart, and begins again at the atrioventricular or AV node, passing down through the AV bundle,(bundle of His) the right and left bundle branches, and finally through the Purkinje fibers and ventricles.
  ECG:   The P wave represents the depolarization (contraction) of the atria. The QRS complex represents the depolarization (contraction) of the ventricles and the T wave represents the repolarization (relaxation) of the ventricles. The repolarization (relaxation) of the atria is hidden in the QRS complex.
    The sympathetic nervous system increases heart rate, and reaches the heart through the cardiac accelerator nerves. (This is why on medical shows you will see them giving epinephrine "epi" to patients in V fib- it is a hormone associated with the sympathetic nervous system.) The parasympathetic system (craniosacral system) uses acetylcholine and reaches the heart through the Vagus nerve where it slows the heart rate. If it wasn't for input from the parasympathetic nervous system our heart rate would be 100 (the rate set by the pacemaker of the heart) instead of about 72.
    Review the definitions of arteries and veins, and the pulmonary circuit of blood flow!!
    In fetal circulation the foramen ovale and ductus arteriosus bypass the developing lungs, and the ductus venosus bypasses the liver. There are two umbilical arteries which branch off the internal iliac arteries of the fetus, and carry poorly oxygenated blood from the fetus to the placenta. There is one umbilical vein that carries well oxygenated blood from the placenta back into the baby through the ductus venosus and into the inferior vena cava. You will see fetal circulation again on exam 2. PROMISE !

EXAM 2:
    Review the conduction system of the heart!! Remember that the sino-atrial or SA node is the pacemaker, the impulse spreads through the atria, but cannot pass into the ventricles due to the fibrous skeleton of the heart. There is a very brief pause when the impulse is started in the ventricles at the AV node and ventricular contraction begins. This pause allows a little extra time for filling of the ventricles.
    Where do the nerves that influence heart rate come from? The autonomic nervous system influences the rate of the heart ( but the basic rhythm of contraction is set by the heart itself). The parasympathetic innervates the heart through the Vagus nerve ( cranial nerve X - remember that the parasympathetic system is called the craniosacral system because it uses cranial nerves and sacral spinal nerves). Impulses from the parasympathetic system slow the heart rate. This influence of the parasympathetic nervous system is fairly constant, since the intrinsic rhythm of the heart is 100 beats per minute, but the influence of the parasympathetic nervous system slows it down to about 72 beats per minute.  The sympathetic nervous system increases the heart rate, and travels through the accelerator nerves.
    Please remember: the mitral or bicuspid valve is located on the left side of the heart between the left atrium and left ventricle. The tricuspid valve is on the right side of the heart between the right atrium and the right ventricle. The aortic (semilunar) valve is located between the left ventricle and the aorta, so blood leaving the left ventricle passes through it, and the pulmonary (semilunar) valve is located between the right ventricle and the pulmonary trunk (an artery).
    The ductus arteriousus and the foramen ovale bypass the fetus's developing lungs, and the ductus venousus shunts blood around the developing liver.
    The P wave of an ECG shows atrial contraction (depolarization). The QRS complex represents ventricular contraction (depolarization) and the T wave shows ventricular relaxation ( repolarization). The wave that represents the  relaxation (repolarization) of the atria is hidden (over whelmed by) the QRS complex.
    Starling's Law states that the more the heart is stretched by the volume of blood that enters the ventricles during ventricular diastole (relaxation), the greater the force of contraction during ventricular systole (contraction). This mechanism allows the heart to instantly regulate itself and increase the force of contraction to expel all the blood from the chambers.
    The normal blood pressure at the right atrium (central venous pressure) during diastole should be about 0 mm Hg to allow blood to flow into the right side of the heart. (Normal clinical range about 5 -10 mm Hg). DO NOT CONFUSE THIS WITH NORMAL DIASTOLIC PRESSURE IN THE ARTERIES - what we measure with our sphygmomanometers!!!!
    The hepatic portal system - one of the places in the body where we have two capillary beds in a row - collects blood from the small intestines, most of the large intestine, stomach, spleen, pancreas, mesentery, etc. and brings it into the liver, where the liver can remove and store excess glucose as glycogen, phagocytize any foreign particles or microorganisms, and detoxify any harmful substances that we have ingested with our food before that blood is sent out through the systemic circulation.
    Saliva acts to moisten our food, dissolve substances in the food, buffer acids in the food, acts as a lubricant during swallowing ( ever tried to take a pill without water? - you can do it if you can salivate enough!!) and contains an enzyme (amylase) for digesting starches (complex carbohydrates).

EXAM 3:
    The liver DOES NOT produce digestive enzymes!! While it has many functions in the METABOLISM of lipids, proteins and carbohydrates, it does NOT make enzymes that allow these substances to be broken down and taken into the body. The closest that it comes is making bile, which emulsifies or breaks fat droplets into smaller particles. This increases their surface area and gives the digestive enzymes of the pancreas and those located in the brush border of the small intestine more room to work. The liver detoxify substances and store glucose as glycogen, also stores iron, and fat soluble vitamins. See the hepatic portal system above. Another major function of the liver is to make plasma proteins - such as albumin to maintain blood osmotic pressure, and clotting factors for the blood.
    Think about mentally "walking" through the large intestine or colon. You leave the small intestine and pass into the colon through the ileocecal valve. You are now in the cecum, and over to your left you can see the opening into the appendix.  The walls here are smooth, (compared to the villi, microvilli and circular folds of the small intestine) with some pits similar to those in the stomach. Here in the large intestine, the person absorbs water and makes feces. The colon makes no enzymes, so any digestion that occurs here is done by the numerous bacteria that we see all around us. They are not just "freeloaders", however, they pay their rent by making vitamins for us, like vitamin K which is need by the liver to make clotting factors. The walls of the colon are arranged in pouches called haustra. Turning right, you pass through the ascending colon, moving from haustrum to haustrum, until you come to the hepatic or right colic flexure. Here we will turn to our right, going toward the person's left side now, traveling through the transverse colon until we reach another bend in our "road". This is the splenic, or left colic flexure. From here we turn right again, and enter the descending colon, then the "S" shaped sigmoid colon, rectum, anal canal, and passing by the two anal sphincters, we leave the body.
    The trachea contains "C" shaped rings of cartilage, and bronchi contain complete rings of hyaline cartilage, but the bronchioles do not contain cartilage. The walls of the bronchioles have smooth muscle, and can constrict or dilate under the influence of the parasympathetic or sympathetic nervous systems respectively.
    The cells of the respiratory membrane are the type I cells of the alveoli and the endothelial cells of the capillaries. Both of these cells are simple squamous epithelium, very thin cells to make it easy for diffusion of gases to take place across them. Anytime you need diffusion to take place across cells you should be thinking simple squamous epithelium!!!! You certainly would NOT want multiple layers of cells.
    Yes, I will admit this had the aspect of a "trick question" but I wanted to see if you would read and think, or just give a "knee jerk" response: How many primary bronchi go to the right lung? Well, how many right lungs do you have? Only one! There are 3 secondary bronchi in the right lung and 2 in the left, but that was not what I asked!!!!
    This is weird - more of the lower students in the class got this one than the upper students!!!! When you hold your breath, CO2 builds up in the blood (it increases), and more Carbonic Acid is formed, which dissociates into bicarb and hydrogen ions (H+). More hydrogen ions means more acid, and a lower pH (number less than 7). The opposite happens when you breath too fast - you "blow off" carbon dioxide, and more hydrogen ions bind with bicarb to form carbonic acid which is then broken down into carbon dioxide and water. Here we have tied up hydrogen ions, so we have fewer H+ and a higher pH.
    A lot of you misidentified the collecting duct in the diagram of the nephron - the diagram I used was similar to that on page 279 of your text, but I did not show the peritubular capillaries.
    Remember that there are three layers to the filtration membrane: The endothelium of the glomerular capillaries allows all substances smaller than cells to pass through (holds back cells) ; the second layer is the basement membrane of the capillaries which holds back large proteins, and the third layer is the slit membrane between the pedicels of the podocytes which holds back medium-sized proteins.
    Under normal conditions ( where Tmax is not exceeded) 100 % of the glucose( and other substances) is reabsorbed from  the proximal convoluted tubules.
  The renal corpuscle, the proximal and distal convoluted tubules are located in the cortex of the kidney.  The nephron loop (of Henle) and the collecting ducts are (mostly) located in the medulla of the kidney - see   figure 20.13 on page 782 of your text book.
    Renin is a hormone which acts as an enzyme to activate the renin-angiotensin pathway. It turns the inactive angiotensinogen into angiotensin I which is converted in the lungs (by ACE - angiotensin converting enzyme)  to angiotensin II. Angiotensin II is a potent vasoconstrictor (causes blood vessels to constrict, raising systemic blood pressure) and also stimulates the release of aldosterone and ADH so that sodium and water can be reabsorbed from the urine, maintaining a higher blood volume, which also increases blood pressure.  It also stimulates thirst to increase water intake, again to increase blood volume.

EXAM 4:
    Remember that the function of the nephron loop (of Henle) is to produce a concentration gradient in the medulla of the kidney. This allows us to produce a concentrated urine through the counter-current multiplier.
    Diabetes insipidus is caused by low ADH production. When we have an absence of ANTIdiuretic hormone we get diuresis- the production of lots of urine with lots of water and a low specific gravity. Diabetes mellitus causes diuresis because all the sugar in the urine draws water with it, but the specific gravity is still relatively high. This is called osmotic diuresis.
    ANP- atrial natriuretic peptide (hormone) is the sodium and water LOSING hormone. Aldosterone is the sodium and water retaining hormone.
    The MOST EFFECTIVE way of dealing with excess acids is by excretion by the kidney. The kidney can eliminate acids from the body (unlike buffers which only tie them up and the respiratory system which can only deal with carbonic acid) while retaining bicarbonate ions.
    Our body compensates for metabolic acid-base imbalances through the respiratory system - breathing faster to raise pH or slower to lower it; and compensates for respiratory acid-base problems metabolically - mostly elimination through the kidneys.
    Remember that steroid hormones, being based on cholesterol, are lipids and can pass through the cell membrane and do not need second messengers to function like protein hormones do. Steroid hormones enter the cell and bind with receptors in the nucleus and alter transcription.
    The hormones of the posterior pituitary gland are actually produced in the hypothalamus (where the cell bodies of the neurons are) and the hormones are only released from the posterior pituitary gland or neurohypophysis.
    Glucocorticoids, such as hydrocortisone or cortisol, along with growth hormone and glucagon, raise blood glucose levels. The bad things it does are to suppress the immune system (why we use it for transplant patients and why you get sick when you experience periods of stress) and decrease your ability to memorize!!
    Thyroid Stimulating Hormone is a tropic hormone produced by the anterior pituitary gland that acts on the thyroid gland to cause the thyroid gland to make T3 and T4.
    The cells of the males that produces testosterone are located in the testes and are the interstitial (Leydig) cells. LH acts on these to cause them to produce testosterone -  remember that in the male LH used to be called ICSH or interstitial cell stimulating hormone.
    Males do not put acids into the secretions which contribute to semen; the  secretions of these glands tend to be alkaline to neutralize the acid in the male urethra and female reproductive tract. These secretions DO have some energy source for the sperm (citrate or fructose), proteins to coagulate semen and enzymes to liquefy it, and prostaglandins that cause contractions in the female reproductive tract.
    There are two corpora cavernosa in the penis and one corpus spongiosum which surrounds the urethra; that is why the section of the urethra that passes through the penis is called the penile or spongy urethra.
    Erection of the penis is caused by the parasympathetic nervous system ("feed and breed") and ejaculation is caused by the sympathetic nervous system.
    Remember that there is a three day "window" when conception can occur- two days before ovulation and one day after ovulation. So the ovum can be fertilized for about 24 hours after it is ovulated.
    Female hormones: There is a "dialog" between the anterior pituitary gland and the ovaries. It starts when the ant. pit. gland produces follicle stimulating hormone which causes a follicle in the ovary to mature. This follicle in the ovary produces estrogen which causes the ant. pit. gland to produce ( and store temporarily) luteinizing hormone. When the estrogen reaches a certain level (meaning the follicle is mature) it causes the release of LH from the ant. pit. and this causes the ovary to ovulate - release the ovum - and form the corpus luteum in the ovary. The corpus luteum continues to produce some estrogen but also produces a lot of progesterone. If implantation does NOT occur, the levels of estrogen and progesterone drop and menstruation occurs.
    The endometrium has two layers: the stratum functionalsis, which is shed during menstruation, and the stratum basalis, or basal or bottom layer which regenerates the functional layer after menstruation.
    The placenta acts as the site for exchange of gases, nutrients and wastes between mother and fetus and produces hormones to maintain pregnancy, but there is normally no mixing of maternal and fetal blood (at least until the  birthing process).