Chapter 16
Puberty is events that a child goes through in order to become sexually competent young adults it happens between the ages of 11 & 13 in girls and 14 & 16 in boys. Until puberty is complete, the reproductive system does not begin to fully function and at this time the individual is capable of producing children.
Reproduction organs have these functions:
In men they produce sperm within testes, and in females they produce eggs within ovaries.
Males nurture and transport sperm in ducts till it leaves the penis and in females they transport eggs in uterine tubes to the uterus.
The penis delivers sperm to the vagina that receives the sperm. The vagina also is the exit for menstrual flow and is the birth canal.
The uterus allows the fertilized egg to develop in her body. After the birth the female breast provides milk.
The testes and ovaries produce sex hormones that help maintain the testes and ovaries and have effects on the body. In the females the sex hormones allow pregnancy to continue.
Male Reproductive Organs and their function:
There are two testes and they are suspended in the sacs of the scrotum and they produce sperm and sex hormones. Sperm matures in a tightly coiled duct lying outside each testis. Mature sperm is required for it to swim to the egg.
These tightly coiled ducts where sperm matures are called epididymides.
Vasa deferentia is another storage place for sperm after leaving the epididymides. Each Vas deferens passes into the abdominal cavity where it curves around the bladder and empties into the ejaculatory duct.
Urethra is where the ejaculatory ducts enter and it conducts sperm. The urethra carries either urine or semen at different times.
Seminal vesicles, Bulbourethral glands and prostrate gland each contribute fluid to the semen. The seminal vesicles also add nutrients.
Penis is an organ of sexual intercourse. During sexual arousal nerves release nitric oxide, and this stimulus leads to the production of cyclic guanosine monophosphate which causes the smooth muscle of the arterial walls to relax. The erectile tissue will fill with blood and the veins that take blood away from the penis are compressed and the penis becomes erect. Ejaculation occurs as sexual stimulation intensifies, sperm enters the urethra from each vas deferens and the glands contribute secretions to the seminal fluid. Rhythmic muscle contractions cause it to be expelled from the penis in spurts. At the time of ejaculation, sperm leaves the penis in a fluid called semen.
The penis is covered by a layer of skin called foreskin. Shortley after birth this skin is surgical removed.
The prostrate can become enlarged in older men which squeezes off the urethra making urination painful and difficult. This condition can be treated medically.
Erectile dysfunction or impotency occurs when the erectile tissue does not expand enough to compress the veins. Medications can treat Erectile dysfunction by inhibiting the enzyme that breaks down cyclic guanosine monophosphate making it possible for a full erection.
Condoms are 97% effective in preventing pregnancy if they are used right. The reason is because a condom catches seminal fluid because it is placed over the erect penis so that it does not enter the vagina.
Mature sperm contain a head, middle piece and a tail. Mitochondria are in the middle piece that provides energy for the movement of the tail. The head has a nucleus covered by a cap which stores enzymes needed to penetrate the egg. Flagellated sperm is very small compared to the egg. As it swims to the egg it is specialized to carry only chromosomes and the egg is specialized to wait for the arrival of the sperm.
Testosterone is the main sex hormone in males. It is essential for the normal development and function of the male reproductive organs. It also brings about male sex characteristics and development of muscles. Males development of hair on face, chest and other regions such as their back is due to testosterone.
Female Reproductive Organs and their function:
Oviducts also called uterine or fallopian tubes and they extend from the uterus to the ovaries. They are not attached to the ovaries but they have finger like projections that sweep over the ovaries. An egg bursts from an ovary during ovulation into an oviduct and this is where fertilization occurs. Zygote formation which is the first cell of a new human being takes place in these oviducts.
Uterus is where the developing embryo arrives after several days. The uterus is referred to as the womb because it houses the embryo and this is where development of the embryo and fetus takes place. The uterus is a muscular organ about the size and shape of an inverted pear. Endometrium is the lining of the uterus which participates in the formation of the placenta. The placenta supplies nutrients needed for fetal development.
Ovaries, there are two and they produce eggs and sex hormones. An ovary contains follicles and each one contains an oocyte which is an immature egg. Only a small number of follicles ever mature because a female usually produces only one egg per month during the ovarian cycle.
Cervix is at the lower end of the uterus and contains the opening to the uterus and it enters the vagina nearly at a right angle. A small opening in the cervix leads to the vaginal canal.
Vagina is a tube that lies to the small of the back. The vagina serves as the birth canal and receives the penis during sexual intercourse. It also is the exit for menstrual flow.
The urinary and reproductive systems in a female are entirely separate unlike a male. The urethra carries only urine whereas the vagina serves as the birth canal and organ to receive the penis during intercourse.
A pap test is very important for early detection of cancer in the cervix. The pap test is done by removing cells from the region of the cervix and examining them under a microscope. If the cells from the pap are cancerous they may recommend that you have a hysterectomy. A hysterectomy is the removal of the uterus including the cervix. A radical hysterectomy is removal of the ovaries as well.
The clitoris is the organ of sexual arousal in a female and can swell to two or three times it usual size because it becomes engorged with blood during sexual stimulation. The thrusting of the penis and the pressure of the pubic symphyses of the partners’ act to stimulate the clitoris.
Estrogen and Progesterone are hormones that affect not only the uterus but other parts of the body too. Estrogen is responsible for the secondary sex characteristics in females like body hair and fat distribution. Both hormones are required for breast development.
If an egg is not fertilized by a sperm cell than it dies shortly after be released from the ovary. When appropriate the vesicular follicle bursts releasing the egg surrounded by a clear membrane which is ovulation.
Menopause occurs in a women’s life between the ages of 45 and 55 and this is when the ovarian cycle ceases. The ovaries are no longer responsive to the gonadotropic hormones and the ovaries no longer secrete estrogen and progesterone. At the onset menstruation becomes irregular. However it is still possible for a woman to conceive as long as it occurs. Menopause is not considered complete until menstruation is absent for a year.
The different forms of contraceptives (birth control) are the intrauterine device, hormone skin patch, Depo-Provera, diaphragms and spermicidal jelly, female condom, male condom, implant and oral contraception. Natural family planning which is keeping records to determine day of ovulation. Pregnancy can’t occur when the female is not ovulating. Each one has a different effectiveness and has different side affect on different people. Abstinence (not engaging in sexual intercourse) is the most reliable form of birth control.
Tubal ligation consists of cutting and sealing the oviducts on a female, pregnancy rarely occurs because passage of the egg through the oviducts has been blocked.
Vasectomy consists of cutting and sealing the vas deferens on both sides on a male so sperm can not reach the seminal fluid that is ejected at the time of orgasm.
Both tubal ligation and vasectomy are methods that bring about sterilization and are permanent.
Infertility is the failure of a couple to achieve pregnancy after one year of regular unprotected intercourse. There are several causes of infertility in males and females. The most common cause in males is low sperm count. The most significant factor in females is body weight.
The different types of sexually transmitted diseases (STD’S):
STD’S CAUSED BY VIRUSES:
Genital warts carriers might not have any signs. When present the warts are mostly found on the penis and foreskin of men and near the vaginal opening in women.
Genital herpes type 1 usually cause cold sores and fever blisters
Type 2 more often causes genital herpes
HIV/AIDS- AIDS is acquired immunodeficiency syndrome. HIV infects and destroys cells of the immune system. Aids is the advanced stage of HIV when a person develops one or more infections due to the immune system being severely weakened.
Hepatitis infects the liver and can lead to liver failure.
STD”S CAUSED BY BACTERIA:
Chlamydia symptoms are in men are mild burning sensation during urination and vaginal as well as symptoms of a urinary tract infection.
Gonorrhea symptoms are pain during urination and a thick greenish yellow urethral discharge in men. Gonorrhea can spread to internal parts of the body causing heart damage or arthritis.
Syphilis has three stages. #1- sore with hard edges which indicates the site of infection #2- break out in a rash that does not itch #3- this stage last until the person dies and may affect cardiovascular system by causing aneurysms. The disease may affect the nervous system resulting in psychological disturbances. Large ulcers may develop on the skin or within internal organs.
Chapter 17
Fertilization is the joining of sperm and egg to form a zygote the first cell of the new individual then it goes over the process the sperm cell goes through to fertilize an egg.
Pre Embryonic and embryonic development
Process of development
Cleavage happens right after fertilization then the zygote divides first into 2 then 4,8,16 and 32 cells. Cell division during this stage is mitotic and each cell will receive a full complement of chromosomes and genes.
Growth during the embryonic development cell division happens by an increase size of the daughter cells.
Morphogenesis is the shaping of the embryo and is shown when certain cells are seen to move or migrate in relation to other cells. By each one of these movements the embryo begins taking shape.
Differentiation when cells form a specific structure and function, differentiation occurs. The first system that becomes visible is the nervous system.
Stages of development
The first week of pre embryonic development happens during this time.
Second week the embryo usually begins the process of implanting itself in the wall of the uterus.
Third week two important organ systems are formed and start appearing. The organs are the nervous system and development of the heart begins.
Fourth and Fifth weeks the embryo is barely larger then the height of this print.
Sixth through eighth week the embryo changes to a form that is easily recognized as a human being.
The normal gestation period is 280 days, however only about 5% of babies actually arrive on the predicted date. A doctor can calculate the due date by adding 280 days to the start of the womans last menstruation date.
Pregnancy and birth
When first pregnant the women might experience nausea, vomiting, loss of appetite, and fatigue. Although some women say that during this time they have increase in energy. Also during pregnancy the mother gains weight due to breast and uterine enlargement weight of the fetus, amount of amniotic fluid, size of the placenta, her own increase in total body fluid and an increase in storage of proteins, fats and minerals. The increase in weight can result in lower back problems. The uterus relaxes, the pulmonary values increase there can be other problems as the uterus enlarges.
Birth
At first the uterus has light contractions but near the end of pregnancy the contractions may become stronger and more frequent. The uterine contractions are induced by a stretching of the cervix that also brings the release of oxytocin from the posterior pituitary gland. Prior to the first stage of parturition which is the process of giving birth to an offspring there can be a bloody show caused by expulsion of a mucous plug from the cervical canal.
Stage 1
The cervical canal slowly disappears as the lower part of the uterus is pulled upward towards the baby’s head. The baby’s head then acts as a wedge to assist cervical dilation.
Stage 2
The uterine contractions occur every 1-2 min and last about 1 min. They are followed by the desire to push and bear down. As the baby’s head is into the vagina the desire to push increases. When the head get to the exterior it turns so the back of the head is uppermost. As soon as the head is out, the doctor may hold the head and guide it downward while one shoulder and then the other emerges. Once the baby’s breathing is normal the umbilical cord is cut and tied severing the child from the placenta.
Stage 3
The placenta or afterbirth is delivered during the third stage of parturition. 15 minutes after delivery the uterine muscular contraction shrink the uterus and dislodge the placenta. The placenta then is expelled into the vagina.
Development does not cease once birth has occurred. It continues through the stages of life. Infancy, childhood, adolescence and adulthood. Aging contributes to progressive changes that contribute to an increased risk of infirmity, disease and death. Research indicates that aging has a genetic basis.
No comments:
Post a Comment