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Category: Biology
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Tags: produce, lining, uterus, primary, embryo, prevents, divide, follicle, develops, secondary, progesterone, diploid, oocytes, haploid, mitosis
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79057556197500Male Reproduction System
2495550523875DNA - haploid
00DNA - haploid
244792545212000Pathway of Sperm
Sperm made in testes
Pass to the epididymis
Along the sperm duct [vas deferens]
Seminal vesicle and prostate gland secrete specific fluid to aid sperm
Leaves as semen
Through urethra
2905125-50482500Formation of sperm [Spermatogenesis]
Stimulated by two hormones:
Follicle-stimulating hormone [FSH] released from pituitary gland
Testosterone released from testes
Sperm is produced in the testis
Cells divide by mitosis to produce 2 diploid [2n] primary spermatocytes
These primary spermatocytes then divide by meiosis to produce 4 haploid [n] secondary spermatocytes
These then divide to produce 4 haploid spermatids[immature sperm cells]
-314325-25717500In the Lumen:
-1181100419735Seminiferous tubule
00Seminiferous tubule
Spermatids attach to nutritive Sertoli cells [protects sperm from toxins in the blood and provide food]
Here they develop in to mature sperm cells
Sperm cells are then stored in epididymis
49530048260000Female Reproduction System
2752725305435vulva
00vulva
Ovaries produce the ova
The ovum travels down the oviduct[fallopian tube] to the uterus [muscle organ richly supplied with blood vessels]
227647517145000Ovum
Much larger than sperm
Does not move on its own
Needs greater energy reserves [such as lipids for zygote development]
-276225-790575Formations of a Ovum
00Formations of a Ovum
28575-25717500
148590099695Primary oocyte
00Primary oocyte
131381526162000
11137904318000-24765043180By mitosis, the follicle develops into diploid primary oocytes when the female is born
00By mitosis, the follicle develops into diploid primary oocytes when the female is born
1038225-381000
4371975229235The secondary oocyte, a mature follicle, is called Graafian follicle
00The secondary oocyte, a mature follicle, is called Graafian follicle
-857251968500-142875229235The primary oocytes divide by meiosis to form haploid secondary oocytes
00The primary oocytes divide by meiosis to form haploid secondary oocytes
125730012319000
220980014605000
Menstrual Cycle
Hormones
Oestrogen – stimulates repair and growth of uterus lining. It is always secreted from Graafian follicle before the ovum is released into the oviduct.
Estradiol – made by Graafian follicle
- high levels stimulate anterior pituitary gland to secrete LH [Luteinizing Hormone], which cause the follicle to release an ovum into fallopian tube
Progesterone – maintains the uterus lining as a thick, spongy layer.
When an ovum is fertilized, the corpus luteum continues to secrete progesterone [and little oestrogen] and stops when the placenta secretes progesterone
When an ovum is not fertilized, the corpus luteum breaks down, the level of progesterone falls and the lining of the uterus breaks down.
95259271000
Secondary Sexual characteristic
Pituitary gland produces hormones [FSH – the primary preparatory hormone of ‘reproduction’] which stimulate the ovaries to produce oestrogen and progesterone; and the testes to produce testosterone.
Characteristics of:
Testosterone in a male
Oestrogen in female
Vocal cords elongate and voice breaks
More fat is deposited in body
Body muscle grows
Pelvis widens
Hair grows on face, chest and armpits
Hair grows on armpits
Pubic hair grows
Pubic hair grows
Male sex organ increases in size
Growth spurt
Sex organ develops in size
Testes produce sperm
Ovaries and menstruation occurs
Sexual maturity is reached at puberty. The period during the approach to puberty is adolescence.
Fertilization
Ejaculation [caused by contraction of muscle tissue in the sperm ducts, seminal vesicles, and prostate glands] of semen is expelled and deposited near cervix
191452524955500The ovum has a membrane that prevents more sperm getting in once one sperm has already penetrated it.
The mechanism ensures:
Zygote [fertilized egg] becomes a diploid zygote
Enables the zygote to divide by mitosis to form a an embryo [ a ball of cells]
Implantation
The embryo is wafted by ciliated cells lining of the oviduct to the uterus, where the embryo sinks into the soft lining of the uterus.
Development of Placenta
Placenta is formed when the outer layer of cells of the embryo produces finger-like projections called villi. These villi penetrate into the blood spaces of the uterus lining. Small blood vessels develop inside the villi.
The part of the lining next to the embryo thickens and this maternal part becomes the placenta.
The embryo then develops into a fetus [called that when limbs and eyes are recognizable]
275272525590500Functions of Placenta
Act as an endocrine gland to produce hormones [oestrogen and progesterone]
Exchange of substances while keeping blood separate:
Diffusion into placenta
Oxygen
Lipids
Amino acids
Glucose
Antibodies [passive immunity]
Diffusion out of placenta
Urea
Carbon dioxide
Amnion
After implantation, a group of cells in the embryo develops into the amniotic sac – contains amniotic fluid [acts as a cushion to reduce mechanical shock; prevents pressure; has large heat capacity which helps to minimize temperature changes]
Ante-natal care
Period of gestation [growth] before the birth of the baby, as the woman gains more weight and extra fat stores thus making her heart beat faster. Therefore she needs:
Calcium and iron
More exercise
More food
Effects of narcotics, smoke and alcohol on Fetus
In the fetus:
Carbon monoxide
prevents haemoglobin from carrying oxygen
Reduces baby’s size
More susceptible respiratory infections
Alcohol
Fetal alcohol syndrome – brain under developed, intelligence is depressed and growth is
delayed/stunted
Narcotics
Born addicted
Physical and mentally handicapped
Advantages of Breast milk
Correct temperature
Free from harmful microorganisms
Passive immunity [antibiotics]
Convenient
Free
Birth Control and Fertility
Methods
NATURAL
Rhythm method [monitor menstrual cycle, have intercourse before ovulation]
Abstinence
CHEMICAL
Contraceptive pill [contains progesterone which prevents ovulation; can increase myocardial infarction, nausea, weight gain, depression and tiredness]
Morning-after pill [oestrogen prevents ovulation, progesterone prevents fertilization and implantation]
Spermicidal cream [kill sperm]
MECHANICAL
Condom
Cap [diaphragm – dome shaped cap that fits around cervix]
IUD [intra-uterine device – piece of metal with projections which fits in uterus; prevents implantation]
SURGICAL
Sterilization [Irreversible]
Vasectomy – vas deferens is cut
Hysterectomy – ovaries remove/uterus remove/fallopian tubes cut
Artificial Insemination
Abundance of collected semen from a donor is inserted into the vagina
Fertility Drugs
FSH/Hormones is given to the women to stimulate ovulation and oestrogen secretion
However, this method can cause multiple ovulations and births [generally the babies die in this case]
‘Test-Tube’ Fertilization
This is when sperm is added to ova, in a dish with the same consistency [pH, Temp., nutrients] as the uterus outside the woman’s body, performed when oviducts are blocked. Then three ova are returned into the woman’s uterus.
Other uses:
Too produce pure-bred beef bulls...as generally the bulls would mate with the milk producing cow and thus create a mix-breed.
Sexual Transmitted Diseases
Lead to infertility and death
Gonorrhea
Caused by bacterium and reside in the lining of male and female reproductive organs. Can be treated with ANTIBIOTICS.
In men:
Sore on penis, discharge of thick yellowish fluid; a burning sensation when urinating
Sperm ducts become block – lead to infertility
In women:
Thick, smelly discharge, burning sensation when urinating
oviducts become block – lead to infertility
Syphilis
Caused by bacterium and reside in ulcers around male and female reproductive organs. Can be treated with ANTIBIOTICS.
After a few months, sores and ulcers form on other parts of body; skin rash and fever symptoms arise.
After a decade, the bacterium has damaged bones, blood vessels, the liver and nervous system. Consequently leads to serious brain damage, insanity and finally death.
HIV
The virus enters the body by sexual fluids and blood. Slowly breaks down immune system and this HIV positive organism may develop a disease called AIDS – which they may die from relatively minor infections such as pneumonia, TB, etc.
Prevention
Test sexual partners
Have one partner
Use a condom during intercourse
Use sterilized needle and gloves when dealing with blood
Educating people bout risks and consequences – encourage safe sex
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