Sunday, November 23, 2008

Unit 4 Section 1 Compendium Review









I. Reproductive System
A. Human Life Cycle
1. Mitosis and Meiosis
B. Male Reproductive System
1. Orgasm in Males
2. Male Gonads
3. Hormonal Regulation
C. Female Reproductive System
1. Genital Tract
2. External Genitals
3. Orgasm in Females
D. Female Hormone Levels
1. Ovarian Cycle : Non Pregnant
2. Estrogen and Progesterone
3. Uterine Cycle :Non Pregnant
4. Fertilization and Pregnancy
E. Control of Reproduction
1. Birth Control Methods
2. Infertility
F. Sexually Transmitted Diseases
1. STDs caused by Viruses
2. STDs caused by Bacteria
II. Development and Aging
A. Fertilization
1. Steps of Fertilization
B. Pre-Embryonic and Embryonic Development
1. Processes of Development
2. Extraembryonic Membranes
3. Stages of Development
C. Fetal Development
1.Events
2. Development of Genitals
D. Pregnancy and Birth
1. Stages of Birth
E. Development after birth
1. Hypothesis of Aging
2. Effect of Age on Body Systems

The reproductive system is very different in males and females.  Puberty is the series of events that brings about sexual maturity in humans.  The reproductive organs have several different functions.  First of all, the testes produce sperm in males, and the ovaries produce eggs in females.  Males transport the sperm in ducts and females transport the eggs in the uterine tubes.  The male penis delivers sperm to the female vagina.  The uterus helps the fertilized egg to develop within a female.  The testes and ovaries produce sex hormones that maintain the testes and ovaries and cause masculinization and feminization of several features.
Human DNA is distributed among 46 chromosomes inside the nucleus.  Every cell in the human body has that number of chromosomes.  When a cell divides by mitosis, or duplication division, the cell produces exact copies of itself.  Human cells also can go through another process of division called meiosis, or reduction division.  During meiosis, the number is reduced to 23, or the haploid number of chromosomes.  Meiosis is the process by which sperm and egg cells are produced.  Since the sperm cell has 23 chromosomes, as does the egg, when they combine they become a zygote and have the full 46 chromosomes.
The primary sexual organs, or gonads, are called testes which are within the scrotum.  Sperm is produced by the testes and mature in the epididymis.  Sperm has to reach maturation in order to swim to an egg.  After leaving the epididymis, the sperm enter a vans deferens where they are stored.  The vas deferens curve around the bladder and empty out into an ejaculatory duct which enters the urethra.  During ejaculation, sperm exits the penis in a fluid called semen.  Seminal fluid is made up of secretions from the seminal vesicles, the prostate gland, and the bulbourethral glands.  Each individual component of semen appears to have its own function.  Sperm are more viable in basic solutions which is what seminal fluid is.  Swimming sperm require energy, which they get from fructose.
The male organ of sexual intercourse is called the penis.  It has a long shaft and an enlarged tip.  This tip is usually covered by a layer of skin called the foreskin, although some penises are circumcised (removal of foreskin).  There is spongy erectile tissue that extends through the penis and contains distensible blood spaces.  When a male is aroused, nerves release nitrous oxide which produces cGMP, causing the smooth muscle of incoming arterial walls to relax and the erectile tissue to fill with blood.  This causes the penis to become erect.  When sexual stimulation intensifies, sperm enters the urethra.  Once the seminal fluid is in the urethra, ejaculation occurs which is caused by rhythmic muscle contractions.  This is part of a male orgasm.  After ejaculation, the penis returns to a flaccid state.  There are up to 400 million sperm released during ejaculation.
The testes begin descending during the last two months of fetal development.  They form inside the abdominal cavity, but descend down into the scrotal sacs.  The scrotum helps to regulate the temperature of the testes by holding them closer to or further away from the body.  A testis is composed of lobules which contain seminiferous tubules.  This is where spermatogenesis, or production of sperm, occurs.  It takes 74 days for sperm do develop from spermatogonia.  Spermatozoa, or mature sperm, have three parts - the head, the middle piece, and the tail.
Androgens are the male sex hormones.  They are secreted by cells between the seminiferous tubules.  This is why they are called interstitial cells.  The most important androgen is testosterone.
The hypothalamus secretes the hormone gonadotropin releasing hormone, which controls the testes' sexual function.  There are two different GRHs - follicle stimulating hormone and luteinizing hormone.  These are present in males and females.  Testosterone brings about the male secondary sex characteristics that appear during puberty.  Some of these characteristics are taller height, broader shoulders, and deeper voices.  Testosterone is also what causes greater muscle development.

Ovaries are the female gonads.  They lie on each side of the upper pelvic cavity and produce eggs, along with the female sex hormones estrogen and progesterone.  The oviducts, which are more commonly known as the fallopian tubes, extend from the uterus to the ovaries.  They end in fingerlike projections called fimbriae.  When an egg bursts from the ovary, it is swept into an oviduct by both the fimbirae and the cilia that lines the oviducts.  When the egg is in the oviduct is is propelled toward the uterus by muscle contraction and ciliary movement.  Unless it is fertilized, and egg only lives 6-24 hours.  When an egg is fertilized it becomes a zygote.  In several days, a developing embryo arrives at the uterus and begins implantation.  The uterus is the size and shape of an upside down pear.  The oviducts join with the uterus at its upper end and the cervix is at its lower end and enters the vagina.
Development of the embryo and the fetus takes place in the uterus, or the womb.  The endometrium is the lining of the uterus and participates in forming the placenta.  There is a small opening in the cervix leading to the vaginal canal.  The vagina acts as an exit for urine and menstrual flow and is the female sexual organ.
The vulva are the external female genitals.  They include two large folds of skin called the labia majora.  The labia minora are the two smaller folds.  The vagina starts out with a ring of tissue called the hymen protecting it.  The hymen is ruptured by sexual intercourse or other physical activities.  
During stimulation, the labia minora, vaginal wall, and clitoris become engorged with blood.  During this time the vagina expands and elongates.  Mucus secreting glands provide lubrication for entry of the penis.  At the height of stimulation, orgasm occurs.
Ovaries contain many follicles, each one containing an immature egg, or oocyte.  Females are born with up to two million follicles, but by puberty that number has dropped to 3 0r 4 hundred thousand.  Only about 400 follicles ever reach maturity.  The ovarian cycle is when the follicle matures.  It changes from a primary to a secondary to a vesicular follicle.  Females usually only produce one egg per month.  An oocyte undergoes meiosis I.  The secondary oocyte undergoes meiosis II if it is fertilized by a sperm cell.  When it is time, the vesicular follicle bursts, releasing the oocyte in a process called ovulation.  The ovaries provide eggs and the sex hormones estrogen and progesterone.  The hypothalamus has complete control of the sexual function of the ovaries through its secretion of GnRH.  
Estrogen is responsible for body hair and fat distribution as well as other secondary sex characteristics.  Also, the pelvic girdle is wider and deeper in females.  The period in a woman's life during which this whole cycle ceases is called menopause.  This usually occurs between the ages of 45 and 55.   Estrogen and progesterone affect the endometrium which causes the uterus to undergo a 28 day series of events known as the uterine cycle.  During the first 5 days, the hormone levels are low, causing the endometrium to disintegrate and the blood vessels to rupture.  This is when menstruation occurs.  During days 6-13, increased production of estrogen by a new ovarian follicle causes the endometrium to thicken.  This is called the proliferative phase.  On the 14th day, ovulation usually occurs.  During the last half of the cycle, progesterone production increases and the endometrium triples in thickness preparing to receive a developing embryo.
After unprotected sexual intercourse, sperm will make there way into the oviduct.  Once a sperm (only one) fertilizes the egg it becomes a zygote.  This begins pregnancy.  The placenta originates from maternal and fetal tissues.  This is the region where exchange of molecules between maternal and fetal blood occurs.  The placenta begins to produce human chorionic gonadotropin, or HCG.  A pregnancy tests for this hormone.  Then the placenta produces progesterone as well as some estrogen.
Birth control pills are taken to help prevent pregnancy from occurring.  They are taken for 21 days and contain synthetic sex hormones.  After that 7 days of inactive pills are taken.  These hormones feed back and inhibit the hypothalamus and the anterior pituitary.  They also thicken cervical mucus, preventing sperm from entering.
There are several means of birth control used to try to prevent pregnancy.  Abstinence, or refraining from intercourse, is the only foolproof method.  Contraceptives are medications and devices that reduce the risk of pregnancy.  Oral contraceptives are pills.  Another method is an intrauterine device which is a small piece of molded plastic that a physician inserts into the uterus.  A diaphragm is a soft latex cup that lodges behind the pubic bone and fits over the cervix.  Barrier methods include female and male condoms.  Injections and vaccines are also available.  
There are more permanent methods of contraceptives. Vasectomy consists of cutting and sealing the vas deferens so that sperm cannot reach the seminal fluid.  Tubal ligation is when the oviducts are cut and sealed.
There is a new pill out called a morning after pill which is considered an emergency contraceptive.  This contains synthetic progesterone which disrupts the uterine cycle and makes it difficult for an embryo to implant.
The failure of a couple to achieve pregnancy after regular, unprotected intercourse is called infertility.  Approximately 15% of all couples are infertile.  The most common cause of this is low sperm count in the male.  A sedentary lifestyle is the most common cause of male infertility.  Body weight is the most significant factor in female infertility.
There are many assisted reproductive technologies available for infertile couples today.  Artificial insemination by donor is when sperm is placed in the vagina by a physician.  Normally the sperm is from an anonymous donor.  In vitro fertilization is when conception occurs in laboratory glassware.  Immature eggs are retrieved by a needle and brought to maturity before concentrated sperm is added.  After 2-4 days they are transferred to the uterus of the woman.  Gamete intrafallopian transfer is when the egg and sperm are immediately placed in the oviducts after being brought together.  In some instances, woman are paid by other women to have their babies.  There is one last technology called intracytoplasmic sperm injection where a single sperm is injected directly into an egg.
There are several types of sexually transmitted diseases, or STDs.  These are caused by viruses, bacteria, protists, fungi, and animals.  There is effective treatment available for AIDS and genital herpes, which are caused by viruses.  AIDS is the last stage of an HIV infection.  There is no cure, but a treatment called highly active antiretroviral therapy is able to stop HIV reproduction to where it is not detectable in the blood.  Human papillomaviruses are the cause of genital warts.  Genital herpes is caused by herpes simplex virus.  Symptoms can include tingling or itching sensation before blisters appear on the genitals.  Hepatitis is an infection in the liver and can lead to death.
STDs that are caused by bacteria are curable with antibiotics.  Chlamydia is usually mild in women.  Men may feel a mild burning sensation during urination.  Gonnorhea's symptoms include pain upon urination, and a thick greenish yellow discharge.  It can also cause infertility in males.  If a baby is exposed during birth, they may develop an eye infection leading to blindness.  This is why all newborns are given eyedrops.  Syphilis has three stages.  During the primary stage, a chancre shows the site of the infection.  The secondary stage is when the victim develops a rash and hair loss may occur.  The tertiary stage lasts until death.
Sperm have a tail called a flagellum which allows it to swim.  The plasma membrane of the egg is surrounded by the zona pellucida.  The cells surrounding this area are called the corona radiata.  During fertilization, several sperm attempt to penetrate the corona radiata.  When a sperm head binds to the zona pellucida, digestive enzymes are released forging a pathway for the sperm.  When the sperm binds to the egg, their plasma membranes fuse.  
As a human being develops, four separate stages occur.  The first stage is cleavage.  Immediately after fertilization, the zygote divides creating multiple cells while not growing in size.  The second stage is growth, in which the daughter cells begin to increase in size.  Next is morphogenesis, or the shaping of the embryo.  Differentiation is the stage when the cells take on a specific structure and function.
Extraembryonic membranes are not a part of the embryo.  There are several functions of the extraembryonic membranes.  The chorion develops into the fetal half of the placenta.  The allantois extends away from the embryo and accumulates the urine produced by fetal kidneys.  The yolk sac is the first of the embryonic membranes to appear.  It contains food for the developing embryo.  The amnion enlarges as the embryo enlarges, containing fluid for protection.  The stages of development include fertilization through birth.  Preembryonic development includes the first week.  Following fertilization, the zygote repeatedly divides as it passes into the uterus.  A blastocyst is a compact ball of embryonic cells.  Each cell within the cell mass has the capability of becoming any type of tissue.  Occasionally, the cells of the morula separate, forming twins.
Embryonic development encompasses the second week through the end of the second month of development.  At the end of the first week, the embryo implants itself in the uterine wall.  Occasionally, an embryo implants itself elsewhere, causing an ectopic pregnancy.  This type of pregnancy is not successful.  During the time of implantation, the chorion secretes enzymes that digest some of the tissue and blood vessels of the uterus.  It also begins to secrete human chorionic gonadotropin.  During this second week, the inner cell mass becomes the embryonic disk and the yolk sac and amniotic cavity form.  During the major event of gastrulation, the inner cell mass becomes the embryonic disk.  During the third week of development, the nervous system becomes the first organ system to be visually evident.  A thickening appears along the entire length.  The neural folds meet at the midline and the neural tube is formed.  Development of the heart also begins this week.  At four weeks, the embryo is only about a quarter of an inch in size.  A body stalk connects the embryo to the chorion.  The head and the tail lift up.  The umbilical cord forms.  Limb buds begin to appear and the head enlarges.  The sense organs become visible.  Between the sixth and eighth week of development, the embryo changes into a form recognizable as a human.  The nervous system begins to develop reflex actions.
At the end of eight weeks the embryo is 1.5 inches long and weighs about the same as an aspirin tablet.
The placenta is where progesterone and estrogen are produced during pregnancy.  They prevent any new follicles from maturing and they maintain the endometrium.  The placenta's fetal side is contributed by the chorion and the maternal side consists of uterine tissues.  The umbilical cord contains the umbilical arteries and vein.  The arteries carry oxygen poor blood to the placenta.  The vein carries blood that is rich in nutrients and oxygen away from the placenta to the fetus.  
The third through ninth months of development are known as fetal development.  Head growth begins to slow down during the third month.  Fingernails, nipples, eyelashes, eyebrows, and hair appear.  Cartilage is slowly replaced by bone.  Sometime during the third month males are distinguishable from females.
During the fourth month, the fetal heartbeat can be heard by placing a stethoscope on the mother's abdomen.  At the end of this month the fetus is about 6 inches long and weighs about 6 ounces.
The mother begins to feel movement sometime during the fifth and seventh months.  During this time the wrinkled skin is covered by a fine down called lanugo which is coated with a white, cheeselike substance called vernix caseosa.
The eyelids are open during this time.  At the end of the seventh month, the fetus is about 12 inches long and weighs about 3 pounds.  If the fetus was born now, it is possible to survive.
At the end of nine months the fetus is about 20.5 inches long and weighs about 7.5 pounds.  The fetus usually rotates during the end of development so that its head is pointed toward the cervix to prepare for birth.  If the fetus does not turn and is rump down, a breech birth is likely to occur.  This makes it difficult for the cervix to expand and a cesarean section may be how the baby needs to be delivered.
The sex of a person is determined as soon as fertilization occurs.  Males have XY chromosomes and females have XX chromosomes.  It is impossible to tell just by inspection whether an unborn child is a boy or a girl during the first several weeks of development.  Gonads begin developing during the seventh week.  At 14 weeks, the primitive testes and ovaries are located deep inside the abdominal cavity.  At fourteen weeks the urogenital groove has disappeared in males and the scrotum forms.  In females, the groove persists and becomes the opening for the vagina.  
The absence of one or more of the sex hormones causes ambiguous sex determination.  In this case, the person has the external appearance of a female but the gonads are absent.  In androgen insensitivity syndrome, the individual develops as a female because the receptors for testosterone are ineffective and the external genitalia develop as a female.  However, the individual has testes inside the body.
When a woman first becomes pregnant, she may experience nausea and vomiting, loss of appetite, and fatigue.  These symptoms usually subside and the mother has a period of increased energy levels.  Weight gain is caused due to breast and uterine enlargement, weight of the fetus, amniotic fluid, the size of the placenta, and other factors.  The increased weight can cause lower back pain.



myself at 7 months pregnant

The arteries in the uterus expand and this leads to low blood pressure.  An increase in the number of red blood cells follows and cardiac output increases by 20-30%.  The uterus ends up occupying most of the abdominal cavity.  Compression of the ureters and urinary bladder can result in stress incontinence.  Compression of the inferior vena cava can result in edema and varicose veins.  Stretch marks, or striae gravidarum typically appear over the abdomen and lower breasts as a result of stretching of the skin.
Throughout pregnancy, the uterus has contractions.  Near the end of pregnancy, contractions become stronger and more frequent.  False labor contractions are called Braxton Hicks contractions.  The onset of true labor is contractions that occur regularly every 15-20 minutes and last for at least 40 seconds.  Parturition is the process of giving birth to an offspring.  Prior to the first stage, there can be what is known as a "bloody show" which is caused by the expulsion of a mucous plug from the cervical canal.
During the first stage of labor, the uterine contractions occur and the cervical canal slowly disappears.  The lower part of the uterus is pulled toward the baby's head.  This is called effacement. If the amniotic membrane has not ruptured, it may do so during this phase.  Stage one ends when the cervix is completely dilated.
During stage 2, the uterine contractions occur every 1-2 minutes and last for about a minute.  This is accompanied by a desire to push.  As the baby's head descends it turns so that the back of the head is uppermost.  An episiotomy is sometimes performed to enlarge the vaginal orifice.  Once the head is delivered, the physician holds the head and guides it downward until the rest of the baby is out.  Once the baby is breathing normally the umbilical cord is cut.
The third stage is when the placenta, called the afterbirth is delivered.
Development does not end at birth.  It continues throughout our lives during infancy, childhood, adolescence, and adulthood.  Aging is the progressive changes that contribute to an increased risk of infirmity, disease, and death.  Gerontology is the study of aging.  The number of people over the age of 65 will increase 147% in the next half of a century.  The human life span is a maximum of 120-125 years.
There are three hypotheses of aging. Several researchers believe that aging has a strong genetic basis.  They have worked with roundworms and found many genes whose expression decreases life span.  Another theory contains a whole body process;  This is due to a decline in the hormonal system which affects many organs of the body.  Some of the diseases and problems seen in older humans include diabetes type 2, menopause, and many other things.  The immune system does not perform as well as a person gets older.  Extrinsic factors are another theory for aging.  This states basically that how we take care of ourselves affects how well our bodies will function as we get older.
Age effects many different body systems in many ways.  Skin becomes thinner and less elastic.  This loss of thickness causes some of the sagging and wrinkling of the skin.  There are fewer sweat glands making homeostatic adjustment to heat limited.  Oil glands are also fewer, causing skin to crack.
The leading cause of death today is cardiovascular disorders.  The heart begins to shrink during aging.  Blood flow to the liver is reduced, and the liver does not metabolize drugs very efficiently.  Blood supply is also reduced to the kidneys.  The digestive tract begins to lose tone, and there is a reduction of saliva and gastric juice.  However, few neural cells of the cerebral cortex are lost.  Cognitive skills remain unchanged.  Reaction time slows.  Loss of skeletal mass is common, but can be controlled by exercise.  Females undergo menopause.  Males undergo andropause.  Females on average live longer than males.
Aging is inevitable, but by developing health habits now, we can prepare for successful old age.

4 generations - ages 2 through 85


Images are from these sites:

Saturday, November 15, 2008

Evaluation Unit 3

Self
1. 3 Aspects I am proudest of...I am proud of the compendium reviews I did for this unit - I think they have everything they needed, I am proud of the fact that I was able to involve my daughter once again in the major project, and I am proud of the fact that I managed to get everything done with so little time to do my homework.
2.  2 aspects that could improve...I am still learning my husband's new computer and had a hard time adding pictures to my posts, I also wish I had more time to have worked on the model of the joint 
3. I think my overall grade for this unit should be a B
4.  I think I can do better next time by starting the big project earlier, in case we have more illnesses or whatever that set me back.

Unit
1.  I was most engaged in the chapter on muscles...I thought it was very interesting.
2.  I was most distanced during the first lab with the leeches...my husband's new computer was not doing what I wanted it to do, so it prevented me from enjoying my lab

Ethics Essay Unit 3




Exercise...we all know it is good for us, so why don't enough of us do it?  There is a myriad of excuses for why people don't exercise as much as they should.  There aren't really two sides to this issue since we all KNOW that exercise is a good thing.  Unfortunately, many of us, have excuses of why we don't do it.  There are so many benefits to exercise...it decreases the risk of cancer, helps us feel good physically and mentally, helps improve our health and fitness.  A lot of people simply don't like the inconvenience of exercise.  They don't want to get up earlier to walk to work instead of driving, or they are too tired after work to go for a walk.
I know I don't exercise quite as much as I should, but I do try to fit it in.  My family and I live a block from Walgreens, and 2 blocks from Walmart.  As long as we are not making big purchases, we walk to those locations.
I make sure  my daughter is active as much as possible - her weekly schedule includes a Thursday morning music and movement class, a Saturday morning gymnastics class, and Sunday morning swim time.  She is a bundle of energy, and it doesn't take much to motivate her to get up and get moving.  My husband enjoys riding his mountain bike to and from school when the weather's not terribly cold.  I work in an enviroment where we do a lot of walking and physical activity throughout the day.
There are days when I don't feel like doing anything after getting home from work, and days that I give in and just sit down.  Although, since having a child 2 years ago, the time to just sit down has decreased to nil.  We all owe it to ourselves to make that time to exercise, no matter how worn out we feel.  In the long run, it will help us to be more energetic, healthy people to a much older age in our life.

Major Lab Unit 3





I choose to do a model of the arm with the elbow joint illustrated.  The elbow is able to move because muscle fibers are stimulated which makes them contract by motor neurons.  The axons of the neurons are in the nerves.  When the nerve impulses reach an axon, ACh is released which binds to receptors in the sarcolemma.  The sarcolemma creates impulses that spread down T tubules to the sarcoplasmic reticulum.  This whole process creates movement, enabling a joint to move.
My daughter helped me with this assignment by helping to make the homemade playdough that was used. 
                                                   Raziel adding the flour for the dough

                                                                stirring the dough

                                           kneading food color into the dough



muscle fiber model


calcium in a muscle contraction

model of elbow joint in the arm


closeup of the elbow joint


Here are what were used for the parts :
homemade playdough - bones, muscles, tendons
uncooked spaghetti noodles- myofibrils
Jujubes candy - nucleus
thread of different colors - T tubule, sarcoplasmic reticulum, tropomyosin
Skittles  and Jubues - actin filaments, troponin and Ca2+
packing tape - sarcolemma

Muscle Lab



This lab was to determine the effects of temperature and fatigue on muscle action.  It was interesting to see how fast a muscle wore down.  The first thing I did was to feel muscles that had contracted.
1.  The three changes I observed in a muscle while it was contracted was that it tightened, felt firmer, and was shorter in length.
Then I timed myself to see how many tight fists I could make in 20 seconds.  I was able to make 15.  After soaking my hand in ice water for a minute, that number went down to 12.
2. The cold temperature of the water caused my muscles in my hand to contract slower.  The muscles were slower to respond in making a fist.
The next part of my experiment involved fatigue.  I repeatedly counted how many times I could make a fist in 20 seconds.  I did this trial 10 times with no breaks in between.  My  husband wanted to attempt this also.  Here is the graph
4.  Fatigue made it a lot harder for the muscles to work.  It also caused muscle pain.  The number of times I was able to squeeze the ball steadily decreased.  My husband's decreased, then went up because he was forcing himself to try for opposite results, and then went steadily down again, leaving him sorer than I was.

In conclusion, both temperature and fatigue can slow down muscle function.


Sunday, November 9, 2008

Chapter 11 and 12 Compendium Review



I. Skeletal System
A. Overview
1. Functions
2. Anatomy of a Long Bone
B. Bone Growth, Remodeling, and Repair
C. Bones of the Axial Skeleton
1. The Skull
2. The Hyoid Bone
3. The Vertebral Column
4. The Rib Cage
D. Bones of the Appendicular Skeleton
E. Articulations
II. Muscular System
A. Overview
1. Types of muscles
2. Functions
3. Skeletal muscles of the body
B. Skeletal muscle fiber contraction
1. Muscle fibers
2. Control of contraction
C. Whole muscle contraction
1. motor units
2. energy
3. fast twitch and slow twitch
D. Muscular Disorders
E. Homeostasis

Bones, cartilage, and fibrous connective tissue are all components of the skeletal system. The skeleton plays many important roles in the body.  It supports the body, protects soft body parts, produces blood cells, stores minerals and fat, and permits flexible body movement in conjunction with the muscles.
The main portion of a long bone, or shaft, is called the diaphysis.  Inside is a large medullary cavity, composed of compact bone.  Compact bone is very highly organized and contains osteons, which are tubular units.  Spongy bone is very unorganized in appearance.  Cartilage is more flexible than bone, but not as strong.  It is made up of cells called chondrocytes.  There are three types of cartilage : hyaline, fibrocartilage, and elastic cartilage.  Fibrous connective tissue contains cells called fibroblasts and makes up ligaments and tendons.
There are several different types of cells that are involved in growth, remodeling, and repair of bones.  Osteoblasts are bone forming cells that promote  sending calcium salts into the matrix.  Osteocytes come from osteoblasts and maintain bone structure.  Osteoclasts absorb bone cells.  They break down bones.
The formation of a bone is called ossification.  In a process called intramembranous ossification, bones develop in between the sheets of fibrous connective tissue.  The most common type of ossification is endochondral ossification.  During this process, bone replaces cartilaginous models of the bones gradually. Chondrocytes put down hyaline cartilage.  As the cartilage model calcifies, the chondrocytes disappear.  Osteocytes secrete bone matrix which undergoes calcification.  This forms a bone collar, which covers the diaphysis.  Blood vessels lay down spongy bone.  The spongy bone is absorbed by osteoclasts and becomes the medullary cavity.  A band of cartilage called a growth plate is in between the primary center and all secondary centers.  Once the growth plates close, growth in bone length no longer occurs.  
Hormones, which are chemical messengers, are involved in bone growth.  Vitamin D is converted to a hormone that helps with the intestinal absorption of calcium.  When calcium can't be absorbed, children can develop a condition called rickets.  Growth hormone stimulates growth of the growth plates.
Bone renewal, also known as remodelling, is when bones break down and reform.  Up to 18% of the bones in our body are recycled every year.  Bone recycling helps the body regulate how much calcium is in the blood.
Bone repair happens after a bone breaks or fractures.  There are four steps of repairal.  First, blood escapes and forms a hematoma between the broken bones.  Then, a fibrocartilaginous callus fills the space between the ends of broken bone.  Next, a bony callus joins the bones together.  Finally, bone remodelling takes place.
The axial skeleton is in the midline of the body.  Its main components are the skull, the hyoid bone, the vertebral column, and the rib cage.  The cranium and the facial bones make up the skull.  The cranium is made up of eight bones that fit tightly together.  It protects our brain.  Some of the bones in the cranium contain the sinuses.  The major bones of the cranium share the names of the lobes of the brain.  The facial bones are what give our faces structure.  The most noticeable of these are the mandible, the maxillae, the zygomatic, and the nasal bones.  The hyoid bone is attached to the temporal bones and the larynx.  It anchors the tongue and is where the muscles associated with swallowing attach.  There are 33 vertebrae in the vertebral column.  The vertebral column protects our spinal cord.  In between the vertebrae are intervertebral disks, made up of fibrocartilage which serve the purpose of padding.  The rib cage is also known as the thoracic cage and consists of the ribs and the sternum.  It protects internal organs, yet is flexible.  There are twelve pairs of ribs in the rib cage.  The sternum protects the heart and the lungs.
The bones within the pectoral and pelvic girdles and their attached limbs make up the appendicular skeleton.  There are two pectoral girdles in the body.  Each has a scapula and a clavicle.  These are the shoulder blade and the collarbone.  The humerus comes off the scapula and the radius and ulna come off the humerus.  The hand has many bones, causing it to be capable of great flexibility.  The pelvic girdle is where our pelvis is.  Our legs descend from this, containing the femur, and the tibia and fibula.  The foot, like the hand, has many bones for flexibility.
Bones are jointed.  These joints are either fibrous, cartilaginous, or synovial.  Most fibrous joints are immovable.  Cartilaginous joints are only slightly movable.  Synovial joints permit free movement.
There are three types of muscle tissue in humans : smooth, cardiac, and skeletal.  They all have cells called muscle fibers.  Smooth muscle cells are spindle shaped and usually form sheets.  Smooth muscle does not fatigue easily.  Cardiac muscle is what goes around the heart and forms the heart wall.
Skeletal muscles have many functions.  They support the body, make bones move, help maintain constant body temperature, assist movement in cardiovascular and lymphatic muscles, and help protect internal organs and stabilize joints. Skeletal muscles operate in pairs.  The beginning of a muscle is on a stationary bone and the insertion is on a bone that moves.  
muscles shorten when they contract.
Special names have been assigned to some of the components in a muscle fiber.  The sarcolemma, sarcoplasm, and sarcoplasmic reticulum are the same as a plasma membrane, cytoplasm, and endoplasmic reticulum in any other cell.  The sarcolemma forms T tubules that penetrate the cell and come into contact with parts of the sarcoplasmic reticulum.  The sarcoplasmic reticulum encases thousands of myofibrils.  Skeletal muscles have both light and dark bands.  These bands are called striations.  The thick bands are made up of myosin and the thin ones are made up of actin.
When the muscles are stimulated, calcium is released.  The movement of actin filaments relating to myosin filaments is known as the sliding filament model.  The entire region containing axons is known as the neuromuscular junction.  There are two other types of proteins in an actin filament.  These proteins are tropomyosin and troponin.
A nerve fiber combined with the muscle fibers that it innervates is a motor unit.  All of the muscles in a motor unit contract at the same time.  Maximal sustained contraction is called tetanus.  It is desirable to have good muscle tone, with the muscle being firm and solid.
Muscles have four possible energy sources.  These are muscle triglycerides, plasma fatty acids, blood glucose, and muscle glycogen.  Muscle cells also store ATP which is needed for contraction.  The CP pathway is the fastest way for muscles to produce ATP.  Fermentation can produce two ATPs when glucose is broken down.  Cellular respiration is another way that muscle cells can acquire more ATP.
Fast twitch muscle fibers are designed for strength and are usually anaerobic.  Slow twitch fibers are steadier and more enduring.  Delayed onset muscle soreness is muscles contracting while they are lengthening, and appears 24-48 hours after strenuous exercise.
Common muscular conditions are spasms, convulsions, cramps, facial tics, sprains, and strains.  Tendinitis is when the gliding motion of a tendon is impaired and the tendon is inflamed.  Bursitis is inflammation of a bursa (a sac filled with a smooth, slippery surface that helps muscles and tendons glide).
Muscular diseases can be more serious.  Myalgia is chronic aching muscles.  Muscular Dystrophy is characterized by progressive degeneration of muscles.  Myasthenia gravis is an autoimmune disease affecting the muscles of the face, neck, and extremities.  Lou Gehrig's disease, or ALS, is characterized by the gradual loss of certain abilities.
The skeletal and muscular systems work together to produce movement and to protect body parts.  Bones store and release calcium and blood cells are produced in red bone marrow.  Muscles help to maintain the temperature of the body by constricting or contracting.

I used images from the following sites

Saturday, November 8, 2008

Compendium Review Chapters 13 & 14



I. The nervous system

A. Overview

1. nerve tissue

2. neuron structure

3. myelin sheath

4. nerve impulse

5. action potential

6. synapse

B. Central Nervous System

1. spinal cord

2. brain

C Limbic System and higher mental functions

D. Peripheral Nervous System

1. somatic system

2. autonomic system

E. Drug Abuse

II. Senses

A. Sensory Receptors and Sensations

1. types of receptors

2. how sensation happens

B. proprioceptors and cutaneous receptors

C. Senses of Taste and Smell

D. Sense of Vision

E. Sense of Hearing

F. Sense of Equilibrium


The nervous system is divided into two major sections : the central nervous system, or CNS, and the peripheral nervous system, or PNS.  The CNS consists of the brain and spinal cord, and the PNS consists of nerves.  There are three specific functions of the nervous system :receive sensory input, perform integration, and generates motor output.

There are two types of cells found in nervous tissue.  Neurons transmit nerve impulses in the nervous system, and neuroglia support and nourish the neurons.  There are three specific types of neurons : a sensory neuron takes nerve impulses to the CNS, motor neurons take nerve impulses away from the CNS, and effectors carry out our responses to environmental changes.  All neurons have three parts, a cell body, dendrites, and an axon.

A protective layer called a myelin sheath covers many axons.  In the PNS this covering is formed by Schwann cells.  The gaps in an axon where there is no myelin sheath are called nodes of Ranvier.  Long axons are more likely to have a myelin sheath.  The myelin sheath helps with nerve regeneration in the PNS.

Nerve impulses pass along information in the nervous system.  A voltmeter measures voltage and helps us to study the nerve impulse.  When the axon is not conducting any impulses, the voltmeter registers membrane potential of about 65mV.

An action potential is a rapid change in polarity across an axonal membrane during a nerve impulse.  It requires two types of gated channel proteins : sodium and potassium.

When there is no myelination on an axon, the action potential at one location causes an adjacent part to produce an action potential.  When an impulse has passed by each portion of an axon, a refractory period occurs and the sodium gates will not open, ensuring that the action potential does not move backwards.

All axons branch into many fine endings tipped by an axon terminal which is very close to the dendrite or cell body of another neuron.  This area of close proximity is known as a synapse.  Transmission across a synapse is carried out by neurotransmitters.  There are more than 100 substances known to be neurotransmitters.  A single neuron is on the receiving end of many signals.  They integrate these signals, summing up excitatory and inhibitory signals.  Excitatory signals cause an axon to transmit a nerve impulse, an inhibitory prohibits the axon from doing so.

The CNS is made up of the spinal cord and the brain.  Both of these are protected by bone.  They are also wrapped in protective membranes known as meninges.  The CNS is composed of gray matter which contains cell bodies and nonmyelinated fibers, and white matter which contains myelinated axons that run together in tracts.

The spinal cord begins at the base of the brain and extends into the vertebral canal.  The spinal nerves project from the cord i between the vertebrae.  The central canal contains cerebrospinal fluid.  The spinal cord is the means of communication between the brain and peripheral nerves.  The center for thousands of reflex arcs is in the spinal cord.  

The cerebrum is the largest portion of the brain.  It is the last center that receives sensory input and carries out integration.  It coordinates activities of all other parts of the brain.  The cerebrum has two halves, called cerebral hemispheres.  Each hemisphere is divided into lobes - the frontal lobe, parietal lobe, occipital lobe, and temporal lobe.  Each lobe is associated with different functions.  The cerebral cortex is a layer of gray matter that covers the cerebral hemispheres.  The primary motor area is located in the frontal lobe.  The primary somatosensory area is in the parietal lobe.  This is where sensory information from the skin and skeletal muscles arrives. Integration occurs in places called association areas. Processing centers receive information from other association areas.  The prefrontal area uses this information to reason and plan actions.  The ability to speak is dependent on two areas called Wernicke’s area and Broca’s area.

The cerebellum is under the occipital lobe of the cerebrum.  It receives sensory input from the eyes, ears, joints, and muscles.  The brainstem contains the midbrain and the medulla oblongata which regulates heartbeat, breathing, and blood pressure.  The reticular formation is a main component of the reticular activating system which arouses the cerebrum and causes a person to become alert.

The limbic system is what controls our emotions and higher mental functions.  This system is located deep in the cerebrum.  The amygdala can cause experiences to have emotions associated with them and creates fear.  The hippocampus is important to learning and memory.

Memory is defined as the ability to hold a thought in mind.  Learning is the ability to retain and utilize past memories.  There are several different types of memory :

short term, long term, semantic (letters. numbers, words) and episodic(persons and events).

There is another type of memory called skill memory which is involved in performing motor activities as we learn them.  Language comes from semantic memory.  

The left and right hemispheres of the brain serve different functions.  The left half is associated with verbal, logical, and rational thoughts.  The right is associated with nonverbal, intuitive, and creative thoughts.

The peripheral nervous system, or PNS, is where our nerves are.  Humans have a dozen pairs of cranial nerves that are attached to the brain.  There are 31 pairs of spinal nerves which emerge from the spinal cord. A dorsal root ganglion is the cell body of a sensory neuron.

The somatic system is part of the PNS.  It serves the skin, skeletal muscles, and tendons.  These nerves take sensory information from external receptors to the CNS and motor commands to the skeletal muscles.

The autonomic system is another part of the PNS.  Its function is to regulate the activity of cardiac and smooth muscles and glands.  It is divided into two areas.  The sympathetic division kicks in in emergency situations, accelerating the heartbeat and dilating the bronchi.  The parasympathetic division promotes all of the internal responses coming from a relaxed state.

Drugs can affect the nervous system and alter the mood or emotional state.  Drug abusers take drugs that affect the reward circuit to where they neglect their basic needs and continue drug use.  Drug abuse becomes obvious when a person is taking a drug at a dose level and under circumstances that can increase the risk of a harmful effect.

Alcohol is the most accepted form of drug use.  It can have harmful effects on the brain and the body.  It very easily crosses the blood brain barrier and causes damage to several tissues, including the liver and the brain.

Nicotine is another common form of drug use.  It binds to neurons in the CNS, releasing dopamine. 

While alcohol and nicotine are legal, there are other illegal drugs that are used and cause severe problems in the nervous system.  Some of the more well known ones are cocaine, methamphetamine, heroin, and marijuana.

There are four categories of sensory receptors in humans.  The first type is a chemoreceptor.  These respond to chemical substances in the immediate area.  Pain receptors are a type of chemoreceptors and are naked dendrites that alert us to possible danger.  Photoreceptors respond to light energy and provide us with the sense of vision.  Mechanoreceptors are stimulated by mechanical forces and result in pressure, giving us the sense of touch.  Thermoreceptors are stimulated by changes in temperature.

Sensory receptors generate nerve impulses.  When these impulses arrive at the brain, sensation occurs.

Proprioceptors, cutaneous receptors, and pain receptors send nerve impulses to the spinal cord where they travel to the somatosensory areas of the cerebral cortex.  Proprioceptors are involved in reflex actions maintaining the body’s equilibrium and posture.  They help us to be aware of the position of our limbs in space.  Cutaneous receptors are located in the dermis of the skin and make the skin receptive to touch, pressure, pain, and temperature.

The senses of taste and smell are called chemical senses.  Taste cells and olfactory cells contain chemoreceptors.  Adult humans have about 3,000 taste buds on their tongue.  There are four primary types of taste - sweet, sour, salty, and bitter.  Taste buds have an opening called a taste pore.  Molecules bind to the receptor proteins and generate nerve impulses that go to the brain.  When the reach the gustatory, or taste, cortex, they are interpreted as tastes.

About 80-90% of what we taste is related to smell.  Our sense of smell comes from 10-20 million olfactory cells located high in the roof of the nasal cavity.  Each olfactory cell has only one type of receptor proteins.  Different odors stimulate different olfactory cells.

Our senses of vision requires the eyes and the brain.  The eyeball has three layers - the sclera, the choroid, and the retina.  The lens is located in the choroid layer, and its function is to focus images on the retina.  The lens and the humors assist in this.  Rays of light pass through the lens and light rays are refracted when brought into focus.  The photoreceptor have two structures - rod cells and cone cells.  The retina has three layers of neurons.  The rod cells and cone cells synapse with the bipolar cells which synapse with ganglion cells and the axons become the optic nerve.  There are no rods and cones where the optic nerve exits the retina.  This produces a blind spot in each eye.  In order to reach the visual cortex, optic nerves carry impulses to the optic chiasma.  This is where depth perception comes from.  Some people have distance problems with their eyes.  Nearsighted people have an elongated eyeball causing them to see close objects better than those at a distance.  Farsighted people have shortened eyeballs which cause the opposite vision.  Color blindness is another common abnormality of the eye.

The ear is where we get our sense of hearing.  The ear consists of the outer, middle, and inner sections.  The outer ear consists of the pinna and the auditory canal.  The middle ear begins at the tympanic membrane (eardrum), and ends at a bony wall containing the oval window and the round window.  The inner ear is filled with fluid.  Hearing begins when sound waves enter the auditory canal.  These sound waves vibrate molecules.  The stapes strikes the oval window's outer membrane, causing it to vibrate, which passes pressure to the fluid in the cochlea.  The sense organ for hearing is called the spinal organ which is located in the cochlear canal.  Each part of this organ is sensitive to different wave frequencies.  

The sense of equilibrium also comes from our ears.  Mechanoreceptors in the semicircular canals detect rotational and angular movement of the head, known as rotational equilibrium.  The base of the canals are called the ampulla.  The brain uses information from the hair cells in the ampulla to maintain equilibrium through motor output to skeletal muscles that can right our position in space.  The mechanoreceptors in the utricle and saccule detect movement of the head in the vertical or horizontal, known as gravitational equilibrium.


Images were from these sites

http://academic.wsc.edu/faculty/jatodd1/ap1/muscle.jpg, http://cwx.prenhall.com/bookbind/pubbooks/morris5/medialib/images/F02_01.jp

ghttp://www.faqs.org/health/images/uchr_02_img0126.jpg

http://www.dwp.gov.uk/medical/med_conditions/images/brain.gif

MPj03210900000[1].jpg

nature05401-f1.2.jpg

eye.jpgear.gif

Leech neuron lab write up

photo 1 - manipulator with oscilloscope trace
photo 2 - ultraviolet image of neuron with dye showing shape


The electrode is measuring the effect of different stimulus on the neurons.
Leeches are used for these experiments because their nerve cords are very large, and the neurons are easily accessible.  A sensory neuron transmits impulses to the CNS after a sensory receptor has been stimulated.  A motor neuron conducts nerve impulses away from the CNS and innervates muscles and glands.  I thought it was very interesting the way some cells responded to certain stimulus while not responding to others at all.

Thursday, November 6, 2008

Unit 2 Self Evaluation

1.  Three three aspects that I was proudest of myself in this unit were first of all, my ability to get it all done early so I could enjoy my family vacation, my big lab project where I included my husband and daughter, and the fact that I am able to understand the material where science has always been difficult for me.

2. The two aspects that need improvement are that I wish I had more time to spend on homework, and I think I kind of rushed my compendium reviews this time around.

3.  I think my overall grade for this unit should be a B

4. It could have gone better if I wasn't trying to juggle a full time job, full time taking care of the house, and full time care of a 2 year old (my husband is a nursing student and spends all his time studying or in class so I am pretty much on my own 24/7), and trying to accomplish a class.  But, I will continue doing my best in this class and hopefully one day soon, will have more time to devote myself more fully to my studies.

1.  I was most engaged in this unit with the whole lab on pulse, respiration rate, and blood pressure.  It was fun to let my daughter be included and it was interesting to watch the way those measurements changed.
2. I don't think I ever felt distanced during this unit.
3. I appreciate Professor Frolich's quick responses to questions during the unit.
4.  I didn't find any action puzzling during this unit.
5.  I was surprised at how much fun I had with this unit