Brianna Laplante

Well, since this is my last blog, I decided to write about the super versatile liver.  All throughout A&P II, the liver has been involved in just about every system, and serves many functions throughout our bodies.  The liver is one of the bodies largest and most important organs.  It is very resilient, but it isn’t indestructible.  Everything we eat, drink, breath and absorb through our skin will reach our livers.  I think we already know the key objectives about the liver, therefore, Im gonna share ways to keep our super organ healthy!

1)Only drink alcohol in moderation, if at all (1 or 2 drinks a day over many years is enough to cause cirrhosis!!)

2)Don’t mix other drugs with alcohol (tylenol, etc. can be toxic to the liver even if you drink in moderation.)

3)Get vaccinated for hepatitis B!!

4)Use medications wisely

5)Beware of certain supplements (some herbal supplements are toxic to liver, along with high doses of vitamin A, D and E. 

6)Be careful around toxic chemicals.  (even aerosols)  Be in a well-ventilated room, or wear a mask, toxins can harm the liver.

7)Don’t eat too many fatty foods.  Our livers make all the cholesterol our bodies need.  Eating a well-balanced diet will help the liver function properly.

8)Watch weight and exercise

Well everyone, A&P II was very interesting, I learned a lot…(even more than I thought by brain could take at times haha)…but its been great! Have a great summer break everyone!!!

Glycogen is a polysaccharide of glucose, which functions as the primary short term energy storage in animal cells.  It is made primarily by the liver and the muscles.  Glycogen is found in the form of granules in the cytosol in many cell types, and plays an important role in the glucose cycle.  Glycogen forms an energy reserve that can be quickly be mobilized to meet a sudden need for glucose.  In the liver hepatocytes, glycogen can account for up to 8% of the fresh weight after a meal.  Only the glycogen that is stored in the liver can be used by other organs.  Glycogen is found in muscles at a much lower concentration.  Small amounts of glycogen are found in the kidneys, and even smaller amounts are found in certain glial cells in the brain and white blood cells.  The uterus stores glycogen during pregnancy to nourish the embryo.  Glycogen is broken down when ATP is needed by muscle cells or when blood glucose levels drop too low.  Glycogen synthesis and breakdown is under hormonal control. 

We get glycogen from carbohydrates, natural sugars (fruits, veggies, milk), and complex carbs (grains, cereal, pasta).   

I remembered that cerebral palsy was brought up in class a couple of times.  I was unsure of what this condition was all about…so I did some further research.  Cererbral palsy is a disorder that affects muscle tone, movement and motor skills.  Even simple movements such as standing can be difficult for those with cerebral palsy.  Other vital functions such as breathing, bladder and bowel control, eating and learning are also affected when a child has cerebral palsy.  Cerebral palsy can also lead to other health issues including vision, hearing and speech problems and learning disabilities. 

Cerebral Palsy is usually caused by brain damage that occurs before or during a child’s birth, or during the first 3-5 years of a child’s life.  Cerebral palsy is one of the most common congenital disorders of childhood.  About 500,000 children and adults of all ages have this condition. 

There are 3 types of cerebral palsy:

1) static cerebral palsy-causes stiffness and moving difficulties

2)athetoid cerebral palsy-leads to involuntary and uncontrolled movements

3)ataxic cerebral palsy-causes a disturbed sense of balance and depth perception

There is no cure for cerebral palsy, but treatment, therapy, special equipment and in some cases surgery can help those living with this condition.  Cerebral palsy does not get worse over time. 

Excretion is the process of eliminating waste products of metabolism and other non-useful materials.  It is an essential process in all forms of life.  The process of excretion involves finding and removing waste products from the body.  The excretory system regulates the amount of water and ions present in body fluids. 

The primary organs of excretion are the lungs, liver kidneys and skin.   Waste products gases are carried by blood traveling through veins to the lungs where respiration takes place.  Dead cells and sweat are removed from the body through the skin.  Liquid waste is removed from the body through the kidneys.  During circulation, blood passes through the kidneys to deposit used and unwanted minerals, water, and a nitrogen-rich material called urea.  The kidneys filter waste from the blood, forming urine.  The kidneys funnel the urine into the bladder along 2 seperate tubes called ureters.  The bladder stores the urine until muscular contractions force the urine out of the body through the urethra.  Feces are expelled through the large intestine.  In strict biological terminology, the removal of fecal material is not considered excretion because feces are indigestible foods and they are not metabolic waste.  Removing digestive wastes is done through a process called egestion. 

 The 4 types of metabolic wastes in the human body are water, carbon dioxide, salts and urea. 

*Water is a by-product of dehydration synthesis and respiration

*Carbon dioxide is a by-product of cellular respiration

*Salts are a by-product of neutralization

*Urea is a by-product of protein metabolism, deamination

We expend energy no matter what we are doing, even when sleeping.  The Basal Metablic Rate (BMR) is the number of calories one would burn if they would stay in bed all day.  If you’ve noticed that every year it gets harder and harder to eat whatever you want and stay slim, its because our basal metabolic rates decrease as we age.  When someone deprives themselves of food, their BMR decreases, losing hope of shedding pounds.   However, a regular routine of cardiovascular exercise  can increase BMR, improving health and fitness when the body’s ability to burn energy gradually slows down. 

 If you guys are interested in calculating your basal metabolic rates…check out this website…

http://www.blaha.net/Main%20BMR%20Calculator.php

Factors that influence BMR are age, gender, weight, height, environmental temperature, dieting and exercise habits.  Males have a greater percentage of lean muscle in their body, therefore, they have a BMR that is generally 10-15% faster than women.  An accurate BMR reading requires that a person’s sympathetic nervous system is not stimulated. 

Metabolism is a collection of chemical reactions that takes place in the body’s cells.  Metabolism converts the fuel in the food we eat into the energy needed to power everything we do–from moving, to thinking, to growing.  If metabolism stops, living things die. 

After food is eaten, enzymes in the digestive system break down proteins into amino acids, break down fats into fatty acids and carbohydrates into simple sugars (glucose).  Along with sugar, amino acids and fatty acids can be used as energy sources by the body when needed.  These compounds are absorbed into the blood, which transports them to cells. 

After they enter the cells, other enzymes act to speed up chemical reactions involved with “metabolizing” these compounds.  During these processes, the energy from these compounds can be released for use by the body, or stored in body tissues–especially the liver, muscles and body fat.  In this way, the process of metabolism is really a balancing act involving 2 kinds of activities that go on at the same time–the building up of body tissues/energy stores and the breaking down of body tissues/energy stores to generate more fuel for body functions. 

Anabolism: constructive metabolism

Catabolism: destructive metabolism

Metabolism is a complicated chemical process in the body.  Basal metabolic rate, calorie intake, and hormones are just a few factors that influence metabolism!!  Just like a car stores gas in the tank, the body stores calories–primarily as fat.  If you overfill a car with gas it will spill onto the tar.  Likewise, if you fill the body up with too many calories..they will form excess body fat!

I have a close friends who has Crohn’s disease, so after last night’s lecture on digestion, I realized Crohn’s fits right into the discussion.  Crohn’s disease is an ongoing disorder that causes inflammation of the digestive tract.  Crohn’s can affect any part of the GI tract from the mouth to the anus, but most often, it affects the ilium.  The swelling extends deep into the lining of the affected organ.  The swelling can cause pain and can make the intestines empty frequently, resulting in diarrhea.  Crohn’s disease is an inflammatory bowel disease, the general name for diseases that cause swelling of the intestines. 

The symptoms of Crohn’s disease are very similar to colitis and irritable bowel syndrome, making it often-times difficult for a diagnosis.  Symptoms of Crohn’s include abdominal pain, diarrhea, rectal bleeding and weight loss.  Treatment options for Crohn’s include the use of anti-inflammatory drugs, cortisone, steroids, immune system suppressors, infliximab, antibiotics and anti-diarrheal/fluid replacemation therapies.  Two thirds of people living with Crohn’s will need surgery at some point in their lives.  Surgery becomes necessary when medication can no longer control symptoms. 

It is crucial for people living with Crohn’s disease to follow a nutritious diet and to avoid foods that worsen symptoms.  People with Crohn’s should regularly meet with their physician to keep their condition under control to their best ability.  Although the cause of Crohn’s disease is unknown, it is believed to be an autoimmune disease that is genetically linked!!   Have a great week everyone, enjoy the nice weather! 

Digestion is the process in which the body breaks down food into smaller components that can be absorbed into the blood stream.  In mammals, preparation for digestion begins with the cephalic phase when saliva is produced in the mouth and digestive enzymes are produced in the stomach.  Mechanical and chemical digestion begin in the mouth where food is chewed and mixed with saliva to break down starches.  The stomach continues to break down food mechanically and chemically through the churning of the stomach mixing with enzymes.  Absorption occurs in the stomach and gastrointestinal tract, which finishes with excretion.  Levels of pH play an important role in proper digestion. 

The 4 seperate stages of digestions include:

1-Ingestion: placing food into the mouth

2-Mechanical and Chemical Digestion: mastication to tear and crush the food, and churning of the stomach.  Addition of chemicals such as bile, acid, enzymes and water to break down complex molecules into simple structures

3-Absorption: moving the nutrients from the digestive system to the circulatory and lymphatic capillaries through osmosis, active transport and diffusion

4-Egestion: removal of undigested materials from the digestive tract through defecation

Digestion is a pretty complicated process, think of how amazing our bodies are to be able to break down all the different foods we eat on a daily basis!! The human body is incredible! Have a good week everyone!! Enjoy the beautiful weather!

I am really interested in circulation changes that take place from fetuses to newborns.  Increased uptake of oxygen by lungs/first and subsequent breaths induces avasoconstriction of the ductus venosus and the ductus arteriosis.  Aeration of the lungs at birth is assocatied with..1) a dramatic fall in pulmonary vascular resistance due to lung expansion, 2) a marked increase of pulmonary blood flow, which raises the left atrial pressure above that of the IVC and 3) a progressive thinning of the walls of the pulmonary arteries due to stretching as the lungs expand with the first few breaths.

As the baby takes their first breath the pulmonary alveoli open up leading to 1) decreasing pressure in the pulmonary tissues, 2) blood pressure from the right side of the heart rushes to fill the alveolar capillaries, 3) pressure in the right side of the heart decreases, 4) pressure in the left side of the heart increases as more blood is returned from the well-vascularized pulmonary tissue via the pulmonary veins to the left atrium.  Blood pressure is now high in the aorta and systemic circulation is now well established.  

Control of circulation is a reflex function regulated: 1) peripherally by the baroreceptors in the aortic arch and carotid sinus, 2) centrally by baroreceptors in cardiovascular center of medulla and 3) respiratory and circulatory reflexes are usually strong in heatlhy newborns, but their efficiency of controlling cardiovascular function is susceptible to environmental factors. 

The foramen ovale closes at birth due to decreased flow from placenta to IVC to hold foramen open and because of increased pulmonary blood flow and and pulmonary venous return to left side of the heart causing the pressure in the left atrium to be higher than the right atrium.  The right ventricular wall is thicker than the left ventricular wall because the right ventricle has been working harder.  The right ventricular wall becomes thinner as the work load is evened out.  The umbilical arteries also constrict at birth to prevent loss of infantis blood.  The umbilical cord is not tied for 30-60 seconds so that blood flow through the umbilical vein continues, transferring fetal blood from the placenta to the infant.  Pretty amazing how this all happens!! Have a good spring break everyone!!

In an average lifetime the heart beats more than 2.5 billion times, without ever pausing to rest.  The heart is like a pumping machine, the heart provides the power needed for life.  Here are the essential tips for maintaining a healthy heart and lifestyle… 

Healthy Diet: 

A healthy diet is the best defense against high cholesterol, high blood pressure, and excess body weight.  These are the 3 main contributors to heart disease!!  The American Heart Association says lists the following guide for improving heart-healthy diets:  Eat a variety of fruits and veggies.  (5+ servings per day).  Eat a variety of grain products, especially whole grain and bran, which is particularly good for the heart.  (6+ servings per day).  Include organic milk products, beans, seeds and nuts.  Choose healthy fats like Omega 3 fatty acids from flax, nuts and avacado.  Limit your intake of foods high in calories and low in nutrition.  This includes foods and drinks with lots of added sugar like soft drinks and candy.  Choose food low in saturated fat, trans fat, and cholesterol **Reminder:** animal products such as red meat, chicken, pork and eggs are high in these fats.  Limit your sodium intake to less than 2,300 mg per day.  Limit alcohol intake and try to always maintain your ideal weight!

Exercise:

Remember, the heart is a muscle, and the only way to keep muscles healthy is to exercise!  The trick is to find some form of exercise you enjoy doing, and do it at least 5 times a week to please our hearts and the rest of our bodies, all at the same time!  Exercising can also help us maintain healthy weight levels, which is important to many other factors pertaining to the heart. 

Smoking, Drugs and Alcohol:

The heart’s job is to pump nutrient-rich blood throughout the body.  If you smoke, take drugs or drink excessively, you are giving the heart a lot of extra work.  The heart cannot handle too much extra work over a long period of time.  Over time, the healthy heart will suffer.  Scientists have proven that smoking doubles your risk of having a heart attack, and doubles, triples even quadruples your risk of having sudden cardiac death.  Because drugs are foreign substances, they can really damage your heart.  While drinking in moderation may not pose heart damage, drink heavily is extremely harmful to the heart.  While alcohol flows in the blood stream, the nutrient-rich blood is less able to nourish the heart. 

 The heart is the essential organ in the body, and it is our job to keep it going strong!!! Enjoy

I thought last night’s lecture on blood was really interesting.  Blood is a connective tissue in our bodies that is vital to human survival.  I decided to look up more information on a fairly common blood disorder known as anemia.  Anemia is a condition in which a person’s blood has a below normal amount of erythrocytes/red blood cells, or the red blood cells don’t have enough hemoglobin.  Hemoglobin is an iron-rich protein which carries oxygen from the lungs to the rest of the body.  In people with anemia, their blood does not carry enough oxygen to the rest of the body.  As a result, people with anemia feel tired, along with other symptoms because their bodies are not receiving enough oxygen. 

In severe or prolonged cases of anemia, the lack of oxygen in the blood can cause serious, sometimes fatal damage to the heart and other organs of the body.  In some kinds of anemia, there are low amounts of the the 3 types of blood cells–thrombocytes, erythrocytes and leukocytes.  Certain types of anemia may be severe, long-lasting and life threatening if not diagnosed and treated.  On the flip side, some types of anemia can be mild, short-lived and easily treated. 

After learning the basics about anemia….my main questions was who is at risk??

I soon learned that women and people with chronic diseases are at greater risk for anemia.  Women during their childbearing age are at greatest risk because they lose blood from menstruation and childbirth.  Older adults and infants younger than 2 are also at risk for anemia.  Unfortunately, anemia can also be inherited!  Methods such as consulting your doctor and changing your diet and adding supplements can also help prevent some types of anemia.  More than 3 million people have anemia in the U.S!!  Keep this in mind everyone, especially the ladies in the class!

The thyroid gland is a small gland, usually weighing less than one ounce, located just below the larynx.  It is made up of two lobes that lie along the trachea which are joined together by a narrow band of thyroid tissue, called the isthmus.  During development inside the womb, the thyroid gland originates in the back of the tongue, but it normally moves to the front of the neck before birth.  In rare cases, it fails to move properly and is located high in the neck or even in the back of the tongue.  This abnormal condition is called lingual thyroid.  At other times, it may migrate too far and end up in the chest. 

The function of the thyroid gland is to take iodine, which is found in many foods, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3).  Thyroid cells are the only cells in the body that can absorb iodine.  These cells combine iodine and the amino acid tyrosine to make T3 and T4.  T3 and T4 are then released into the blood stream and transported throughout the body where they control metabolism.  Every cell in the body depends upon thyroid hormones for regulation of their metabolism.  The normal thyroid gland produces about 80% T4 and about 20% T3, however T3 is about four times the hormone strength of T4.

 The thyroid gland is under the control of the pituitary gland, a small gland the size of a peanut at the base of the brain.  When levels of T3 and T4 drop too low, the pituitary gland produces thyroid stimulating hormone (TSH) which stimulates the thyroid gland to produce more hormones.  Under the influence of TSH, the tyroid will manufacture and secrete T3 and T4, raising their blood levels.  The pituitary gland senses these changes and responds by decreasing its TSH production. 

Thyroid cancer is not very common.  Thyroid cancer only accounts for 1.2% of all new cancers in the U.S. annually! The four types of thyroid cancer include papillary, follicular, medullary, and anaplastic.  September is thyroid cancer awareness month.

Since lecture was cancelled this week, I decided to post about lab.  Our sense of hearing is the ability to detect mechanical vibrations we call sound.  Deafness can be inherited or acquired. 

 Acquired Deafness:

If a labratory animal is exposed to very intense, pure tones, the animal eventually becomes deaf to those frequencies, but it’s ability to detect other frequencies are unimpaired.  Examination of its organ Corti reveals destroyed hair cells in a single area whose location can be easily correlated with the pitch of destructive sound.  Similar defecits occur in humans who are exposed to intense noises for long periods. 

Inherited Deafness:

About 1 in 1000 newborns are born deaf because of a genetic defect.  As the years go by, about 16% of humans suffer a progressive loss of hearing due to genetic defects.  Mutations in a transcription factor have been associated with a stapes that cannot move freely and thus cannot transmit vibrations to the oval window.  The proper organization of the stereocilia involves actin, a form of myosin and cadherins.  Mutations in the gene encoding a protein that helps with actin polymerization also cause deafness.  The potassium that enters the hair cells must be removed from them and recycled back to the endolymph for hearing to continue.  Failure for the process to happen is linked to deafness.

*Interesting Facts*

-deaf people have safer driving records than hearing people nationally!

-when Beethoven produced his 9th symphony, he was profoundly deaf

-about 22 million people in the U.S. are hearing impaired

-the man who invented shorthand, John Gregg, was deaf

During last night’s lecture, I quickly became interested in glaucoma.  Glaucoma is sometimes called the silent thief because it can slowly steal your sight before you even realize anything is wrong.  Glaucoma often occurs in animals, as well as humans.  Glaucoma is one of the leading causes of vision loss.  The most common form of glaucoma is primary open-angle glaucoma, which develops slowly with no warning signs.  Other types of glaucoma include angle-closure glaucoma, low tension glaucoma, primary glaucoma and secondary glaucoma.  Many people are unaware of their vision problems until their vision is extensively compromised. 

Symptoms of glaucoma include blurred vision, halos around lights, reddening of the eyes, severe eye pain, nausea and vomitting.  Glaucoma is caused by too much intraocular pressure inside the eye.  Intraocular pressure is like air in a balloon–too much pressure inside the balloon affects its shape, and may even cause it to pop.  In the case of the eye, too much pressure can damage the optic nerve. 

Not to worry..there are many prevention methods for glaucoma.  People who have elevated eye pressure should use glaucoma eye drops on a daily basis, this reduces te risk of developing glaucoma by 22%. Cholesterol lowering medicines also reduce the risk of developing glaucoma, along with frequent monitoring/regular checkups.  Regularly monitoring is the best way to early detect and prevent glaucoma.  Remember to go for annual eye exams to keep your eyes healthy!!

I never realized exactly how fragile the spinal cord was until last night’s lecture.  Last week, I watched NFL player Kevin Everett interview about his spinal cord injury on Oprah.  I soon became very interested in spinal cord injuries.  A spinal cord injury is a serious condition that affects lives dramatically.  

The spinal cord is often injured when vertebrae are broken or fractured and axons are damaged.  Damage prevents messages from getting through, causing many problems.  The body’s chemical responses along with bleeding and swelling can cause additional damage that can continue for days, even weeks after the injury.  The prognosis depends on the location and severity of the injury.  Some patients recover, while others may be paralyzed for life.  About 52% of spinal cord injuries result in quadriplegia and tetraplegia and about 42% result in paraplegia.  The severity of the injury gets worse depending on how high the injury is on the spinal cord.  Remember, C3, C4 and C5 keep you alive!

Spinal cord injuries are labeled complete or incomplete depending on the amount of spinal cord damage.  With a complete injury, messages cannot travel to and from the brain and there is no feeling or movement below the injury.  An incomplete injury is less severe.  An incomplete injury allows for some messages to get through and for limited sensory and motor abilities.  Injuries can also be classified as traumatic or nontraumatic.  Traumatic injuries are sudden, often from a strong force that causes immediate damage.  Nontraumatic injuries tend to develop more slowly from conditions such as arthritis, diseases, cancer, bleeding, infections or degeneration of the vertebrae. 

 Approximately 11,000 people suffer from spinal cord injuries in the U.S. each year!

I really enjoyed learning about fertilization in last night’s lecture. I think it is amazing how a tiny ball of cells develops into a fetus with complex body systems. Pregnancy is measured in trimesters from the day of your last menstrual period, totaling 40 weeks. The first trimester is the period that really interests me. The first trimester of pregnancy includes weeks 1-12, or about 3 months.

Actual pregnancy begins at the time when the egg is fertilized by the sperm cell. During the following week the fertilized egg grows into a microscopic ball of cells (blastocyst), which implants on the wall of the uterus. This implantation triggers many hormonal and physical changes in the body. The third-eighth weeks are called the embryonic stage, during which the embryo develops most major body organs. During this stage the embryo is highly vulnerable to damaging substances such as alcohol, radiation, and infectious disease.

Having reached a little more than 1 inch in length by the 9th week of growth, the embryo is now called a fetus. By this time, the uterus has now grown from the size of fist to about the size of a grapefruit!!

What struck me as interesting during lecture was the discussion on Schwann cells. Schwann cells are a variety of neuroglia that mainly provides myelin insulation to axons in the peripheral nervous system. Schwann cells are named after the German physiologist, Theodore Schwann.

I found some additional information about Schwann cells today. Schwann cells appear under a light microscope when immunostained with an anti-S-100 antibody. Schwann cells begin to form the myelin sheath of mammals during fetal development and work by spiraling around the axon up to 100 revolutions. A well-developed Schwann cells is shaped similarly to a rolled up sheet of paper with layers of myelin between each coil. Many recent experimental studies are implanting Schwann cells into patients with multiple sclerosis to try to induce remyelination. In addition to creating myelin sheaths in the PNS, Schwann cells also aid in cleaning up of debris in PNS and guide the regrowth of PNS axons. Pretty cool!