Ovarian and Uterine Cycles

Key Terms –

Ovarian cycle: the normal cycle of reproductive function and development in the female ovary, which includes development of an ovarian follicle, rupture of the follicle, discharge of the egg, and formation and regression of a corpus luteum (yellow tissue formed in the ovary after the release of the egg).

Uterine cycle: also known as the menstrual cycle, in which the endometrial lining of the uterus prepares for pregnancy. If pregnancy does not occur, the lining is shed at menstruation.  The average menstrual cycle is 28 days.

GnRH: a hormone which is produced by the hypothalamus in the brain. It stimulates the pituitary gland to produce and release both LH and FSH.

LH: a hormone produced during the menstrual cycle. The luteinizing hormone causes an egg to be released from the ovaries.

FSH: (follicle-stimulating hormone) promotes follicle development within the ovary, thus allowing certain eggs to mature and the follicle cells surrounding each egg to produce estrogen in preparation for fertilization.

Estrogen: female steroid sex hormones. They are secreted by the ovary and responsible for typical female sexual characteristics.

Progesterone: a steroid hormone produced in the ovary, which prepares and maintains the uterus for pregnancy.

hCG: (human chorionic gonadotropin) hormone produced early in pregnancy by the placenta. Detection of the hormone in the urine is the basis for one type of pregnancy test.

Positive feedback loops: hormone levels increase after the release of an egg into the ovary because more hormones are needed to ensure proper development of the egg to a fetus.

Negative feedback loops: a decrease in the hormone levels within the body leads to a decrease of the production of GnRH.

Menstruation vs. Pregnancy: hormone levels are much lower during menstruation than during pregnancy because there is no egg for fertilization.

Fetal Development: is the process in which an embryo or fetus gestates during pregnancy, from fertilization until birth.

1^st Trimester – the first twelve weeks of pregnancy: the zygote is turning into a fetus and the embryo is made up of three layers, ectoderm, endoderm and mesoderm. These are the first stages of organ development.

2^nd Trimester – the second twelve weeks of pregnancy: fetus continues to grow and organs are developing. The ectoderm forms skin tissue, the endoderm forms the digestive and respiratory systems, and the mesoderm forms muscles, cartilage, bone and blood.

3^rd Trimester – the third and final twelve weeks of pregnancy: the fetus is growing rapidly. It will fully develop during this period of time.

Immune System

Key Terms –

Pathogens: an infectious agent, or more commonly germ, is a biological agent that causes disease to its host.

Macrophage: a type of phagocyte or white blood cell that digests foreign invaders and damaged tissues.

Antigen: any substance (as a toxin or enzyme) that stimulates an immune response in the body (especially the production of antibodies).

Helper T cell: are a sub-group of lymphocytes (a type of white blood cell or leukocyte) that play an important role in establishing and maximizing the capabilities of the immune system.

B cell: a lymphocyte derived from bone marrow that provides immunity; it recognizes free antigen molecules in solution and matures into plasma cells that secrete immunoglobulin (antibodies) that inactivate the antigens.

Antibody: any of a large variety of proteins normally present in the body or produced in response to an antigen which it neutralizes, thus producing an immune response.

Killer cell: a white blood cell that attacks and kills “foreign” cells, including tumor cells and cells infected with bacteria or viruses.

Cytotoxic T cell: a type of white blood cell that can directly destroy specific cells.

Memory cell: a subset of T-cells and B-cells that have been exposed to specific antigens and can then proliferate (recognize the antigen and divide) more readily when the immune system re-encounters the same antigens.

Problems of the Immune System –

Severe combined immunodeficiency (SCID): is also known as the "bubble boy disease" after a Texas boy, David Vetter, with SCID who lived in a germ-free plastic bubble. SCID is a serious immune system disorder that occurs because of a lack of both B and T lymphocytes, which makes it almost impossible to fight off pathogens in the body. Its victims are extremely susceptible to infectious diseases and some of them, including David who became known as “the bubble boy”, become famous for living in a completely sterile environment. SCID is the effect of a highly compromised immune system.

HIV (human immunodeficiency virus) infection/AIDS (acquired immunodeficiency syndrome): is a disease that slowly and steadily destroys the immune system. AIDS is caused by HIV, a virus that wipes out a specific lymphocyte, helper T cells. Without these cells, the immune system is unable to defend the body against normally harmless organisms. By damaging your immune system, HIV interferes with your body's ability to fight off life-threatening infections and diseases. Newborns can get HIV infection from their mothers while in the uterus, during the birth process, or during breastfeeding. People can get HIV infection by having unprotected sexual intercourse with an infected person or from sharing contaminated needles for drugs, steroids, or tattoos.

Aging

Aging is unavoidable – it is a natural, physiological process that, although can be slowed down or covered up with cosmetic procedures, will happen to everyone. Aging is caused by a combination of genetics and lifestyle.

Genetics account for aging because of our cells dividing, resulting in our telomeres becoming shorter and shorter with each division. “Biological age…is related to the length of telomeres – stretches of DNA at the ends of chromosomes, which protect these precious packages of genes from daily wear and tear. We’re born with telomeres of certain length, and these get shorter as our cells divide, resulting in aging, scientists think” (Moisse, 2010). Aging occurs on a cellular level – eventually cells lose their ability to divide and repair themselves. This loss of capability to divide and repair is known as senescence. As the telomeres become increasingly shorter in the division process, there is the possibility that essential parts of DNA can be damaged with each new divide.

Lifestyle also accounts for aging. “…good habits, such as a healthy diet, regular physical activity and mental exercises that might keep the elderly vibrant through their golden years. The New England Centenarian Study, which includes 850 people entering their 100s, for example, has identified several behavioral and personality traits that seem to be critical to longevity, including not smoking, being extroverted and easygoing and staying lean” (Park, 2010). Taking care of your body can help maintain your youth, while engaging in risky lifestyle choices can speed up the aging process. Lack of exercise increases the risk of cardiovascular disease and diabetes, while smoking not only damages your lungs but also speeds up the rate at which telomeres decay and in turn age your body faster.

Another factor of aging is the relationship between good cholesterol – high-density lipoprotein (HDL) – and health. “HDL plasma concentrations decline with age in prospective studies. Decline in HDL concentration and function may occur secondary because of…specific aging processes [that] may be involved. Replicative aging, the telomere-driven loss of divisional capacity, is a species-specific aging mechanism that may decrease HDL concentration and function. Cross-sectionally, by contrast, HDL levels do not change much or even slightly increase with age, suggesting that only people with still high HDL concentrations survive” (Walter, 2009). People with higher levels of HDL tend to live longer because HDL removes the bad cholesterol – low-density lipoprotein (LDL) – from the body and helps decrease the risk of heart disease.

Works Cited

Moisse, K. (2010). Researchers identify genetic variant linked to faster biological

aging. Scientific American. Retrieved April 11, 2011 from http://www.scientificamerican.com/article.cfm?id=aging-telomere

Park, A. (2010). How to live 100 years. Time. Retrieved April 11, 2011 from

http://www.time.com/time/specials/packages/article/0,28804,1963392_1963365,00.html

Walter, M. (2009). Interrelationships among HDL metabolism, aging, and

atherosclerosis. American Heart Association. Retrieved April 11, 2011 from http://www.atvb.ahajournals.org/cgi/content/full/29/9/1244

Stress

Causes of Stress:

A stressor is a situation that causes stress. Stressors can be classified into three categories –

1.       Accidental hassles: temporary but can cause significant stress

Ex. Losing a house key, having a flat tire, missing the bus or getting a traffic ticket

2.      Major life changes

Ex. Marriage, graduation, having a baby, starting a business, surgery, death in the family, losing a job, or divorce

3.      Ongoing problems

Ex. An unhappy marriage, unstable job, a poor relationship with a family member, coworker or peer, or accumulating debt

Ways to Reduce Stress:

Prevent –

1.       Avoid controllable stressors

2.      Plan major lifestyle changes

3.      Realize your limitations and learn how to say no to things that stress you out and responsibilities you know you cannot take on

4.      Prioritize

5.      Improve communication

6.      Share your thoughts and get advice to avoid/get out of a stressful situation

7.      Develop a positive attitude

8.     Reward yourself with relaxation as you successfully overcome challenges

9.      Exercise

10.  Eat and sleep well

Manage –

1.       Plan by visualizing expected events

2.      Think positively

3.      Imagine potential negative big events and think about what you can do to make them positive

4.      Relax with deep breathing

5.      Relax by clearing your mind

6.      Relax your muscles

7.      Relax with stretching and exercise

8.     Relax with massage therapy

9.      Ask for help

10.  Find professional help from doctors if needed

Effects of Stress:

 

Exercise Physiology

Exercise physiologists oversee the analysis, improvement, and maintenance of health and fitness, rehabilitation of heart disease and other chronic diseases and disabilities, and the professional guidance and counsel of athletes and others interested in sports training. In addition, many exercise physiologists study the effect of exercise on pathology, and the mechanisms by which exercise can reduce or reverse disease progression. There is no license to become an exercise physiologist. Therefore, the range of exercise physiology is extensive. An exercise physiologist's area of study may include but is not limited to biochemistry, bioenergetics, cardiopulmonary function, hematology, biomechanics, skeletal muscle physiology, neuroendocrine function, and central and peripheral nervous system function. Exercise physiologists can be basic scientists, clinical researchers  and even sports trainers.

Key Terms –

VO2 max: (also called maximal oxygen consumption, maximal oxygen uptake, peak oxygen uptake or aerobic capacity) it is the maximum capacity of an individual's body to transport and use oxygen during incremental exercise, which reflects the physical fitness of the individual.

Lactic acid: it is a chemical compound that plays a role in several biochemical processes. Specifically regarding to exercise, when the rate of demand for energy is high, lactic acid is produced faster than the ability of the tissues to remove it, so lactate concentration begins to rise. This is a beneficial process, since the regeneration of NAD+ ensures that energy production is maintained and exercise can continue.

Aerobic respiration: requires oxygen in order to generate energy. Although carbohydrates, fats, and proteins can all be processed and consumed as reactant, it is the preferred method of pyruvate breakdown in glycolysis and requires that pyruvate enter the mitochondrion in order to be fully oxidized by the Krebs cycle. The product of this process is energy in the form of ATP (Adenosine triphosphate).

Anaerobic respiration: it is a form of respiration using electron acceptors and instruments other than oxygen. It is respiration without oxygen.

ATP: Adenosine triphosphate is a multifunctional nucleotide used in cells as a coenzyme. ATP transports chemical energy within cells for metabolism. It is produced by photophosphorylation and cellular respiration and used by enzymes and structural proteins in many cellular processes, including cell division.

CP: Phosphocreatine, also known as creatine phosphate, is a phosphorylated creatine molecule that serves as a rapidly moveable reserve of high-energy phosphates in skeletal muscle and brain.

Glycolysis: it is the metabolic pathway that converts glucose into pyruvate. The free energy released in this process is used to form the high-energy compound ATP.

Carbohydrates: an organic compound that consists only of carbon, hydrogen, and oxygen, with a hydrogen to oxygen atom ratio of 2:1 (as in water).

Fats: consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. Chemically, fats are generally tri-esters of glycerol and fatty acids.

Proteins: they are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form in a biologically efficient way.

Energy Pathways –

1.       ATP-CP splitting for explosive movements and short sprints

2.      Anaerobic glycolysis for longer sprints

3.      Aerobic metabolism for endurance events

Heart Surgeries

Heart Patient X Case Study

Patient: Mr. X

Age: 47

Height: 6’1”

Weight: 235 lbs

History: Mr. X was recently laid off from his stressful job as a real estate agent due to the failing economy. Now his stress level has skyrocketed as he is searching for a job. (He has two teenage children that he must send to college in the next few years and without a job, he won’t have the money to support them.) With no income, he can only afford to eat highly processed fast foods that contain little nourishment. Mr. X was feeling tightness, aching and discomfort in his chest. He initially thought it was heartburn or indigestion and took an over-the-counter drug, Pepto Bismol in hopes that it would go away. His chest pain, called angina, has since worsened and now he is also feeling shortness of breath.

Family History: His mother’s side of the family has a history of obesity and heart attacks.

Tests: Mr. X’s physical examination depicted that he has high blood pressure (hypertension). The EKG test checked for problems with the electrical activity of Mr. X’s heart. These showed that Mr. X had an abnormal heart beat and that there was an underlying problem. An electron-beam computed tomography (EBCT) was performed on Mr. X, which illustrated how severely the calcium build-up in the lining of his arteries had become. The final test, an angiocardiography, was able to show us a radiographic examination of the heart chambers and thoracic vessels by the injection of radiopaque dye. This heart x-ray determined the extent of Mr. X’s coronary artery disease.

Pulmonary Arterial Hypertension and calcium build up in Mr. X’s heart

Diagnosis: Mr. X has coronary heart disease, which is a disease that develops when a combination of fatty material, calcium and scar tissue (plaque) builds up in the arteries that supply the heart with blood. The build up narrows the arteries so that the heart does not get enough blood, causing chest pain (angina) and ultimately if left untreated, a heart attack (myocardial infarction) or a fatal rhythmic disturbance (cardiac arrest).

Treatment: Mr. X should get a coronary bypass to relieve his pain.  This is an invasive surgical procedure performed to improve blood supply to the heart by creating new routes for blood flow since the old routes have been obstructed by plaque build up. The surgery requires the removal of a healthy blood vessel from another part of the body, such as the arm or leg, so that it can be grafted onto the heart to circumvent the blocked artery. Mr. X should also make lifestyle changes, such as reducing his stress level and eating healthier so that he can reduce the risk of worsening his disease. If he does not make these lifestyle changes, Mr. X will likely end up having a heart attack and would need a heart transplant. This would entail removing the diseased heart and replacing it with a new, healthy heart. Transplants can be risky and are not always successful. It would be best if Mr. X made lifestyle changes now and did not go down the path of heart failure before it is too late.

Artificial Organs

The organ in the image above is a bio-artificial ear. It was grown from the patient’s own stem cells.

Scientists are calling regenerative medicine the "Holy Grail" of stem-cell research because tissue regeneration could make invasive surgeries a thing of the past. For instance, a patient with a bladder disease can be grown a new bladder. The whole process takes six to eight weeks, but the results are life-changing and well worth the wait. In order for cell regeneration to work, you must take healthy cells from a patient's diseased bladder, cause them to multiply greatly in petri dishes, then apply them to a balloon-shaped scaffold (structure) made partly of collagen, which is the protein found in cartilage. Muscle cells are put on the outside, while urothelial cells (which line the urinary tract) are put on the inside. The next step is that the structure must then be incubated at body temperature until the cells form functioning tissue.

Artificial Organs
Pros:	Cons:
Engineering tissues can potentially help people conquer illnesses and diseases	If the body tissue used to reconstruct particular tissue had latent or hidden diseases or illnesses, they could carry over to the new tissue
Has the capability of prolonging life/makes the general quality of life better	Many people have ethical issues with using stem cells
Will make organ transplant lists and waiting for donors unnecessary
Stem cells are readily available

Stem Cells

What are stem cells?

Stem cells are essential to human development. They are non-specialized cells, which have the capability of creating other types of specific cells. Stem cells are in our bodies for our entire life, but they have the more potential to create new cells in the fetus than in the adult body. Some types of stem cells may be able to create all other types of cells in the body, while others repair and replace damaged tissue or cells.

Embryonic stem cells are derived from embryos and can create all cell types in the body. However, embryonic stem cells carry the risk of transforming into cancerous tissue after transplantation. To be used in cell transplant treatments, the cells would need to be directed into a more mature cell type, both to be therapeutically effective and to avoid the risk of cancerous tissue development. While embryonic cells hold enormous promise for future therapies, iPS cells are much more widely accepted in the medical community as of right now.

In 2006, scientists figured out how to reprogram cells that had a specialized function (e.g. skin cells, blood cells, muscle cells, etc.) so that they act like an embryonic stem cell. These cells are called iPS cells, which is short for “induced pluripotent cells”. By inducing specialized cells to express genes that are normally expressed in the embryonic stem cell and control how it operates, iPS cells are created. Embryonic stem cells and iPS cells share many characteristics, including the capability of becoming the cells of all organs and tissues. But though they share similar traits, they can sometimes behave slightly differently.

Adult stem cells are specific to a certain tissue, meaning they are found in a given tissue in our bodies and they produce the mature cell types within that particular tissue or organ to repair and maintain that tissue. There are a few stem cell therapies that are common amongst the medical community and they use adult, or tissue-specific stem cells. Bone marrow or cord blood is used in stem cell transplantation to treat diseases and conditions of the blood or to replenish the blood system after treatment for specific cancers. Skin stem cell therapies for burns and limbal stem cells for corneal replacement are also common. In each instance, the stem cells repair the same tissue from which they originated.

Stem cells are able to cure and treat various diseases because they have the ability to become any kind of tissue. This means that, for example, when incorporated into a brain that may be devastated by Alzheimer's disease, they become healthy brain cells, and are then able to help the brain function normally again. Since stem cells have the ability to generate into any form of a healthy cell, stem cells have the means to treat and/or cure a wide spectrum of diseases. These types of diseases include degenerative genetic disorders that currently afflict millions of people, such as Parkinson's disease, multiple sclerosis and muscular dystrophy. In addition to potentially having the ability to treat and cure various diseases and disorders, stem cells have also shown noticeable potential in treating spinal cord injuries. Overall, stem cells could lead to significant benefits for individuals and tremendous gains for society. 

Embryology

Embryology: The scientific study of the development of an embryo from the point of the ovum's fertilization to the fetus stage in its growth.

There are many steps in the development of the embryo. The acrosomal reaction is the first step of fertilization. In this reaction, the sperm must fuse with and then penetrate the egg in order to fertilize it. Fusing the egg is generally very easy for the sperm, however breaking through the egg's protective, hard outer shell can pose a problem for the sperm. This is why the sperm go through the acrosome reaction. The acrosome is a cap-like structure on the head of the sperm. It is made up of surface antigens and numerous enzymes that are responsible for breaking down the egg's outer shell. When the sperm approach the zona pellucida of the egg, the egg's hard outer membrane, they undergo acrosomal reaction. During the acrosomal reaction, the membrane surrounding the acrosome fuses with the plasma membrane of the sperm and exposes the contents of the acrosome. Because its contents break down the tough exterior of the egg, the acrosome allows fertilization to occur.

Once the sperm has broken through the egg's plasma membrane, preventing other sperm from attaching to and entering the egg, the cortical reaction occurs. When the sperm contacts the egg's plasma membrane, it triggers calcium to be released from storage sites within the egg. In response to this, cortical granule membranes fuse with the plasma membrane of the egg, freeing the contents of the granules to the extracellular space. As the release of calcium travels across the egg, a wave of cortical granule fusion results. The contents of the granules differ between species, and are not entirely understood. Take the sea urchin, for example. In this organism, the granule contents alter a protein coat on the outside of the plasma membrane, known as the vitelline layer, so that it is released from the membrane. The freeing of the protein is known as "elevation of the fertilization envelope". As this occurs, non-fertilizing sperm are lifted away from the egg’s membrane and thus prevented from entering the egg, which prohibits polyspermic fertilization.

Once the egg has been fertilized, the organism begins to develop. Cleavage is the first step in the development of all multicellular organisms. It is the division of the cells in the early stages of the growth of the embryo. The single-celled zygote expands into a multi-celled embryo through cleavage. The blastula is produced by the mitosis of the zygote. Also called a blastosphere, the blastula consists of a spherical layer of cells surrounding the blastocoel, a fluid-filled cavity. Due to their rapid division, the size of the cells decreases. However, this increases their surface to volume ratio, which allows a more efficient oxygen exchange to take place between the cells and their environment. During this step of fertilization, RNA is dispersed throughout the blastula. These differentiations in molecular development are the basis for the next stages in development.

Gastrulation is the next step in embryology. It involves a series of cellular changes to positions where they form the three main cell layers. The ectoderm forms the tissues associated with the outer layer of our body such as the skin, hair and sweat glands. Also, the brain and nervous system develop from the ectoderm. The next layer is the mesoderm. It forms structures such as muscles, cartilage, bone, blood and all other connective tissue that support body movement. The mesoderm is also responsible for forming the reproductive systems organs and the kidneys. The inner layer is called the endoderm. It forms tissues and organs associated with the digestive and respiratory systems, as well as many endocrine structures.

Organogenesis is the series of organized, integrated processes that transform an unstructured mass of cells into a complete organ in the developing embryo. Basically, this is the process that creates the definite characteristics of the organs. Internal organs initiate development in humans within the third to eighth weeks in utero. The germ layers differ by three processes: folds, splits and condensation.

So how does this all happen in a sea urchin?

Sea urchin eggs are produced by the female and shed into the water. Sperm from the male is then spread over the eggs. Because sea urchin eggs free-float in the sea and the fertilization process is external, they must protect them. To prevent the egg and sperm from being swept away (or eaten), sea urchins have evolved methods to bring the gametes together, like magnets. When a sperm cell encounters an egg of the same species, it binds itself to the plasma membrane of the egg, triggering the release of calcium that facilitates fertilization. Both the sperm and egg have specific receptors for the other that must transmit a signal sequentially for fertilization to occur. However, all these forces that attract to one another can work too well and bring many sperm to the egg. The fertilization envelope protects the egg from polyspermic fertilization, which would produce an inviable zygote.

Following fertilization, the egg begins the process called cleavage. These early cell divisions occur rapidly. The egg synthesizes proteins using mRNA provided by the mother sea urchin. There are 4 main divisions in the cleavage of the sea urchin embryo. The first 3 cell divisions bisect the embryo equally. The first 2 cleavage planes from the top, known as the animal pole, to the bottom, called the vegetal pole, while the third runs across the middle and separates the embryo into “animal” and “vegetal” halves. The fourth cleavage divides the bottom half unequally, creating large cells called macromeres and small cells called micromeres.

Shortly after hatching, the offspring of the micromeres at the vegetal end detach and move into the blastocoel. These are known as primary mesenchyme cells and they form the calcium carbonate spicules of the larval skeleton.

The descendants of the macromeres thicken to form the vegetal plate, which invaginates to form the primordial gut. This process is known as gastrulation and, in addition to forming the gut, it results in a multilayered body plan.