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8 08, 2018

Hormonal Control of Reproduction in Females – The Ovarian and Menstrual Cycles

By Dr. Joseph H Volker | 2018-08-30T10:35:16+00:00 August 8th, 2018|Physiology, Reproductive System|0 Comments

Reproduction in females is controlled by hormones produced by the hypothalamus, anterior lobe of the pituitary gland, and ovaries. Female Sex Hormones The ovaries produce the two major groups of female sex hormones-estrogens and progesterone-plus inhibin, which aids estrogens in exerting an inhibitory effect on the anterior lobe of the pituitary gland via a negative-feedback [...]

8 08, 2018

Various Methods of Birth Control Work

By Dr. Joseph H Volker | 2018-08-30T10:40:27+00:00 August 8th, 2018|Physiology, Reproductive System|0 Comments

Birth control methods may be categorized into several groups based on their mode of action: hormonal, chemical and behavioral contraceptive methods, anti-implantation devices, sterilization, and induced abortion. Contraception Contraception is the prevention of conception, which is the union of sperm nucleus and ovum nucleus. Contraceptive methods are designed to prevent sperm from reaching and penetrating [...]

8 08, 2018

Disorders of the Reproductive Systems

By Dr. Joseph H Volker | 2018-08-30T10:42:58+00:00 August 8th, 2018|Physiology, Reproductive System|0 Comments

Male Disorders Prostatitis is acute or chronic inflammation of the prostate gland and is often associated with tenderness and enlargement of the prostate. It is usually caused by bacteria in connection with urinary tract infections or sexually transmitted diseases. It also occurs without a known cause. Benign prostatic hyperplasia (BPH) is the enlargement of the [...]

8 08, 2018

The Processes of Fertilization, Preembryonic Development and Implantation

By Dr. Joseph H Volker | 2018-08-30T10:45:01+00:00 August 8th, 2018|Physiology, Reproductive System|0 Comments

Each primary oocyte undergoes the first meiotic division while still in the ovarian follicle. This division forms a secondary oocyte and the first polar body, each containing 23 chromosomes. At ovulation, the secondary oocyte and first polar body, still enclosed within a sphere of granulosa cells, are released into a uterine tube. They are slowly [...]

8 08, 2018

Embryonic Development – Germ Layers, Extraembryonic Membranes and Placenta

By Dr. Joseph H Volker | 2018-08-30T10:46:50+00:00 August 8th, 2018|Physiology, Reproductive System|0 Comments

The embryonic stage of development begins at the start of the third week of development and is completed at the end of the eighth week. During this time, the embryo undergoes rapid development, forming the rudiments of all body organs, extraembryonic membranes, and the placenta. By the end of the eighth week, it has a [...]

8 08, 2018

Fetal Development Stages

By Dr. Joseph H Volker | 2018-08-30T10:49:38+00:00 August 8th, 2018|Physiology, Reproductive System|0 Comments

At the beginning of the ninth week of development, the developing offspring has a distinctively human appearance and is now referred to as a fetus. Weeks of Development Changes 5-8 Weeks Recognizable human shape; head as large as the body; eyes far apart; upper and lower limbs present with digits; heart possesses four chambers; tail [...]

8 08, 2018

Hormonal Control of Pregnancy

By Dr. Joseph H Volker | 2018-08-30T10:50:28+00:00 August 8th, 2018|Physiology, Reproductive System|0 Comments

Without the formation of a preembryo, the corpus luteum degenerates about two weeks after ovulation as a result of the decline in luteinizing hormone from the anterior lobe of the pituitary gland. The resulting decline in blood levels of estrogens and progesterone causes the endometrium to break down and to be shed with menstruation. Pregnancy [...]

8 08, 2018

Male Reproductive System – Locations and Functions of the Male Reproductive Organs

By Dr. Joseph H Volker | 2018-08-30T10:25:09+00:00 August 8th, 2018|Anatomy, Body Systems, Physiology, Reproductive System|0 Comments

The primary functions of the male reproductive system are the production of male sex hormones, the formation of sperm, and the placement of sperm in the female reproductive tract, where one sperm can unite with a female sex cell. The organs of the male reproductive system include (1) paired testes, which produce sperm and male [...]

8 08, 2018

Lactation – The Control of Lactation and Milk Ejection

By Dr. Joseph H Volker | 2018-08-30T10:54:31+00:00 August 8th, 2018|Endocrine System, Physiology, Reproductive System|0 Comments

High blood levels of estrogens and progesterone during pregnancy stimulate the development of the mammary glands and enlargement of the breasts in preparation for milk secretion, or lactation (lak-ta'-shun). Although the mammary glands are capable of secreting milk, the high levels of estrogens and progesterone inhibit the hypothalamus so that milk secretion does not occur [...]

8 08, 2018

Male Sexual Response

By Dr. Joseph H Volker | 2018-08-30T10:27:34+00:00 August 8th, 2018|Physiology, Reproductive System|0 Comments

In the absence of sexual stimulation, the vascular sinusoids in the erectile tissue of the penis contain a small amount of blood and the penis is flaccid (flak'-sid), or soft. Sexual stimulation initiates parasympathetic nerve impulses that cause the dilation of the arterioles and constriction of the venules supplying the erectile tissue. These vascular changes [...]