Best Time to Breed
Whether it's itching, smelling differently, or just off - it's okay. An environmental toxin affecting men's reproductive DNA was introduced circa , causing autism to spike in children. KLIH-tuh-rus , a small sensory organ, is located toward the front of the vulva where the folds of the labia join. Erectile dysfunction is a common condition that affects about one in 10 males on a long-term basis, the Cleveland Clinic noted. The FNB advises against beta-carotene supplements for the general population, except as a provitamin A source to prevent vitamin A deficiency. IVF is a technique of artificial insemination in which the egg and sperm are combined outside the body and then placed in the uterus after the formation of the embryo. Tests to detect ovarian cancer, as well as cancer of the fallopian tube, and primary peritoneal cancer are currently being studied, according to the National Cancer Institute.
However, improved pancreatic replacement treatments, better nutrition, and caloric supplements have helped most patients with cystic fibrosis become vitamin A sufficient [ 21 ]. Several studies have shown that oral supplementation can correct low serum beta-carotene levels in people with cystic fibrosis, but no controlled studies have examined the effects of vitamin A supplementation on clinical outcomes in patients with cystic fibrosis [ ].
This section focuses on three diseases and disorders in which vitamin A might play a role: Because of the role vitamin A plays in regulating cell growth and differentiation, several studies have examined the association between vitamin A and various types of cancer. However, the relationship between serum vitamin A levels or vitamin A supplementation and cancer risk is unclear.
Several prospective and retrospective observational studies in current and former smokers, as well as in people who have never smoked, found that higher intakes of carotenoids, fruits and vegetables, or both are associated with a lower risk of lung cancer [ 1 , 24 ].
In the Carotene and Retinol Efficacy Trial CARET , 18, current and former smokers including some males who had been occupationally exposed to asbestos took daily supplements containing 30 mg beta-carotene and 25, IU retinyl palmitate for 4 years, on average [ 25 ].
In the beta-carotene component of the Physicians' Health Study, 22, male physicians took mg aspirin plus 50 mg beta-carotene, 50 mg beta-carotene plus aspirin placebo, mg aspirin plus beta-carotene placebo, or both placebos every other day for 12 years [ 27 ].
In all three of these studies, taking very high doses of beta-carotene, with or without 25, IU retinyl palmitate or mg aspirin, did not prevent lung cancer.
In fact, both the CARET and ATBC studies showed a significant increase in lung cancer risk among study participants taking beta-carotene supplements or beta-carotene and retinyl palmitate supplements.
The evidence on the relationship between beta-carotene and prostate cancer is mixed. However, the ATBC study found that baseline serum beta-carotene and retinol levels and supplemental beta-carotene had no effect on survival [ 29 ].
The ATBC and CARET study results suggest that large supplemental doses of beta-carotene with or without retinyl palmitate have detrimental effects in current or former smokers and workers exposed to asbestos. The relevance of these results to people who have never smoked or to the effects of beta-carotene or retinol from food or multivitamins which typically have modest amounts of beta-carotene is not known. More research is needed to determine the effects of vitamin A on prostate, lung, and other types of cancer.
Age-related macular degeneration AMD is a major cause of significant vision loss in older people. AMD's etiology is usually unknown, but the cumulative effect of oxidative stress is postulated to play a role. If so, supplements containing carotenoids with antioxidant functions, such as beta-carotene, lutein, and zeaxanthin, might be useful for preventing or treating this condition. Lutein and zeaxanthin, in particular, accumulate in the retina, the tissue in the eye that is damaged by AMD.
A follow-up AREDS2 study confirmed the value of this supplement in reducing the progression of AMD over a median follow-up period of 5 years but found that adding lutein 10 mg and zeaxanthin 2 mg or omega-3 fatty acids to the formulation did not confer any additional benefits [ 32 ].
Importantly, the study revealed that beta-carotene was not a required ingredient; the original AREDS formulation without beta-carotene provided the same protective effect against developing advanced AMD. Measles is a major cause of morbidity and mortality in children in developing countries.
About half of all measles deaths happen in Africa, but the disease is not limited to low-income countries. Vitamin A deficiency is a known risk factor for severe measles. The World Health Organization recommends high oral doses , IU of vitamin A for two days for children over age 1 with measles who live in areas with a high prevalence of vitamin A deficiency [ 33 ].
A Cochrane review of eight randomized controlled trials of treatment with vitamin A for children with measles found that , IU of vitamin A on each of two consecutive days reduced mortality from measles in children younger than 2 and mortality due to pneumonia in children [ 33 ].
Vitamin A also reduced the incidence of croup but not pneumonia or diarrhea, although the mean duration of fever, pneumonia, and diarrhea was shorter in children who received vitamin A supplements. A meta-analysis of six high-quality randomized controlled trials of measles treatment also found that two doses of , IU in infants and , IU in older children significantly reduced measles mortality [ 34 ].
The vitamin A doses used in these studies are much higher than the UL. The effectiveness of vitamin A supplementation to treat measles in countries, such as the United States, where vitamin A intakes are usually adequate is uncertain.
The body needs vitamin A to maintain the corneas and other epithelial surfaces, so the lower serum concentrations of vitamin A associated with measles, especially in people with protein-calorie malnutrition, can lead to blindness. None of the studies evaluated in a Cochrane review evaluated blindness as a primary outcome [ 35 ].
However, a careful clinical investigation of African children with measles revealed that half of all corneal ulcers in these children, and nearly all bilateral blindness, occurred in those with vitamin A deficiency [ 36 ].
Because vitamin A is fat soluble, the body stores excess amounts, primarily in the liver, and these levels can accumulate. Although excess preformed vitamin A can have significant toxicity known as hypervitaminosis A , large amounts of beta-carotene and other provitamin A carotenoids are not associated with major adverse effects [ 37 ].
The manifestations of hypervitaminosis A depend on the size and rapidity of the excess intake. The symptoms of hypervitaminosis A following sudden, massive intakes of vitamin A, as with Arctic explorers who ate polar bear liver, are acute [ 38 ].
Chronic intakes of excess vitamin A lead to increased intracranial pressure pseudotumor cerebri , dizziness, nausea, headaches, skin irritation, pain in joints and bones, coma, and even death [ 2 , 4 , 5 ]. Although hypervitaminosis A can be due to excessive dietary intakes, the condition is usually a result of consuming too much preformed vitamin A from supplements or therapeutic retinoids [ 3 , 5 ]. When people consume too much vitamin A, their tissue levels take a long time to fall after they discontinue their intake, and the resulting liver damage is not always reversible.
Observational studies have suggested an association between high intakes of preformed vitamin A more than 1, mcg daily—only slightly higher than the RDA , reduced bone mineral density, and increased fracture risk [ 1 , 4 , 39 ]. However, the results of studies on this risk have been mixed, so the safe retinol intake level for this association is unknown.
Total intakes of preformed vitamin A that exceed the UL and some synthetic retinoids used as topical therapies such as isotretinoin and etretinate can cause congenital birth defects [ ]. These birth defects can include malformations of the eye, skull, lungs, and heart [ 4 ]. Women who might be pregnant should not take high doses of vitamin A supplements [ 2 ]. Unlike preformed vitamin A, beta-carotene is not known to be teratogenic or lead to reproductive toxicity [ 1 ].
The most significant effect of long-term, excess beta-carotene is carotenodermia, a harmless condition in which the skin becomes yellow-orange [ 1 , 24 ]. This condition can be reversed by discontinuing beta-carotene ingestion. Supplementation with beta-carotene, with or without retinyl palmitate, for 5—8 years has been associated with an increased risk of lung cancer and cardiovascular disease in current and former male and female smokers and in male current and former smokers occupationally exposed to asbestos [ 26 , 40 ].
In the ATBC study, beta-carotene supplements 20 mg daily were also associated with increased mortality, mainly due to lung cancer and ischemic heart disease [ 26 ]. The CARET study ended early, after the investigators found that daily beta-carotene 30 mg and retinyl palmitate 25, IU supplements increased the risk of lung cancer and cardiovascular disease mortality [ 40 ].
The FNB based these ULs on the amounts associated with an increased risk of liver abnormalities in men and women, teratogenic effects, and a range of toxic effects in infants and children. The FNB also considered levels of preformed vitamin A associated with decreased bone mineral density, but did not use these data as the basis for its ULs because the evidence was conflicting.
The FNB advises against beta-carotene supplements for the general population, except as a provitamin A source to prevent vitamin A deficiency. However, many dietary supplements such as multivitamins do not provide all of their vitamin A as retinol or its ester forms.
For example, the vitamin A in some supplements consists partly or entirely of beta-carotene or other provitamin A carotenoids. In such cases, the percentage of retinol or retinyl ester in the supplement should be used to determine whether an individual's vitamin A intake exceeds the UL. That amount is above the UL for children from birth to 13 years but below the UL for adolescents and adults. Vitamin A can interact with certain medications, and some medications can have an adverse effect on vitamin A levels.
A few examples are provided below. Individuals taking these and other medications on a regular basis should discuss their vitamin A status with their healthcare providers.
The manufacturers of Alli and Xenical recommend encouraging patients on orlistat to take a multivitamin supplement containing vitamin A and beta-carotene, as well as other fat-soluble vitamins [ 42 , 43 ]. Several synthetic retinoids derived from vitamin A are used orally as prescription medicines. Retinoids can increase the risk of hypervitaminosis A when taken in combination with vitamin A supplements [ 41 ].
The federal government's Dietary Guidelines for Americans notes that "Nutritional needs should be met primarily from foods. Foods in nutrient-dense forms contain essential vitamins and minerals and also dietary fiber and other naturally occurring substances that may have positive health effects. In some cases, fortified foods and dietary supplements may be useful in providing one or more nutrients that otherwise may be consumed in less-than-recommended amounts.
These hormones play a role in one or more stages of development and function of the female reproductive system. Ovaries produce three varieties of estrogen called estradiol, estrone, and estriol. Estrogens play a role in development of secondary sex characteristics that appear at puberty.
Estradiol plays a role in breast development and promotes fat distribution to breasts, hips and legs. Estrogens are produced by follicles within the ovary and help regulate the menstrual cycle.
Estrogen promotes the rapid growth of cells lining the uterus called the endometrium in preparation for possible implantation and pregnancy. At the end of pregnancy, high levels of estrogen induce the ovaries to produce oxytocin which stimulates uterine contractions.
Estrogen also has non-reproductive functions. Estrogen prevents abnormal blood clotting which maintains heart health. In addition, estrogen helps bones retain calcium which keeps them strong. The natural decline of estrogen with aging often requires medical supplementation with exogenous estrogen to prevent declining heart health and osteoporosis. Do you think that you could fill in a diagram labeling a few organs in the male reproductive system?
Are you able to name some healthy habits that can protect a teen male and his reproductive system? This username and password combination was not found. Concordia University - Online. Learn more about our online M.
Please correct highlighted fields Select One Concordia University - Portland. By submitting this form I ask to receive email, texts and calls about degree programs on behalf of Concordia University - Portland, and agree automated technology may be used to dial the number s I provided. I understand this consent is not required to enroll. Save Print Send Download Report. Growth and Development Lesson: Male Reproduction System National Standard: Affective — After participating in the growth and development unit, the students should be able to demonstrate behaviors related to growth and development, as determined by the responses on a questionnaire.
Materials and Equipment A. There are students in this class period with disabilities, however they will able to participate and accomplish the tasks set forth. Procedure 45 minutes A. Introduction 3 Good morning, class. Today we will be reviewing the male reproductive system. I know that you have recently covered the female reproductive system so can anyone tell me what secondary sex characteristics are?