The skin: largest organ of the body

2021 ◽  
Vol 15 (9) ◽  
pp. 446-451
Author(s):  
Ian Peate

This article concludes this series in the anatomy and physiology of the body systems. An overview of the skin is provided and the various and functions of this, the largest organ of the body, are described. The three layers of the skin are discussed, along with an overview of skin pigmentation. The skin would be unable to complete most of its functions without the help of its appendages. The subcutaneous glands, hair, nails and nerve endings (the appendages) that allow it to function efficiently are summarised briefly. One other function of the skin—vitamin D synthesis—is described. The article ends with a glossary of terms and a set of questions that are intended to assist with leaning.

2021 ◽  
Vol 10 (44) ◽  
pp. 3730-3735
Author(s):  
Rohit Kumar Agrawal ◽  
Preeti Sharma ◽  
Pradeep Kumar ◽  
Mehek Jaggi ◽  
Rachna Sharma

BACKGROUND Exclusive breastfeeding is recommended up to 6 months of age with all its beneficial effects on child survival. Several studies have shown that adequate intake of vitamin D cannot be met with human milk as the sole source of vitamin D, although risk factors for developing vitamin D deficiency may be low maternal levels of vitamin D, indoor confinement during the day, living at higher altitudes, living in urban areas with tall buildings, air pollution, darker skin pigmentation, use of sunscreen and covering much over the body when outside. An infant who is entirely on breastfeeding and has minimal to no exposure to sunlight is more prone to the development of hypovitaminosis-D. The main purpose of the study was to identify the prevalence & high-risk groups of hypovitaminosis D in exclusively breastfed babies. METHODS It was a cross-sectional observational study consisting of 30 entirely breastfed healthy full-term babies with a birth weight > 2.5 kg. Babies born to mothers with a history of pre-eclampsia, gestational diabetes, antepartum haemorrhage, tuberculosis, and other chronic medical illnesses were excluded from the study. The period of study was from 1st August 2019 to 30th September 2019. Their serum vitamin D3, serum calcium, serum phosphate, and alkaline phosphatase levels were measured using appropriate methods. RESULTS In our study, 25 infants out of 30 came out as vitamin D deficient. The prevalence of vitamin D3 was found to be 83 %. CONCLUSIONS Breastfeeding is of utmost importance but the nutritional status of the mother, proper exposure to the sun, and vitamin D supplementation are the factors that should be taken care of for the prevention of hypovitaminosis D. KEY WORDS Vitamin D3, Hypovitaminosis D, Exclusive Breast Feeding, term babies, infants, Sun Exposure, Rickets


Author(s):  
Sofia Khanam

Vitamin D is one of the essential nutrients to sustain the human health. Vitamin D functions in the body through both an endocrine mechanism (regulation of calcium absorption) and an autocrine mechanism (facilitation of gene expression). The role of Vitamin D deficiency in increasing the risk factor of many common and serious chronic diseases, including cancers, type 1 diabetes, cardiovascular disease and osteoporosis. Numerous epidemiologic studies suggest that exposure to sunlight, which enhances the production of Vitamin D₃ in the skin, is important in preventing many chronic diseases. 25(OH)D (25-hydrovitamin D) is the metabolite that should be measured in the blood to determine Vitamin D status. 25(OH)D deficiency is prevalent in infants who are solely breastfed and who do not receive Vitamin D₃ supplementation and in adults of all ages who have increased skin pigmentation or who always wear sun protection or limit their outdoor activities. It is therefore necessary to know the adverse health effects of 25(OH)D deficiency and to design intervention and early treatments for those who are likely to have low levels of 25(OH)D.


2019 ◽  
Vol 9 (o3) ◽  
Author(s):  
Suaad Muhssen Ghazi ◽  
Fatin Shallal Farhan

Vitamin D deficiency is common in women with polycystic ovarian syndrome. Vitamin D plays an important physiologic role in reproductive functions of ovarian follicular development and luteinization through altering anti-müllerian hormone signaling, follicular stimulating hormone activity and progesterone production in human granulose cells. Vitamin D is precipitated in adipose fat tissues, making it notable to be used for the body as a result; obese people with high body mass index are already highly expected to have low levels of serum vitamin D.


Nutrients ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 1408
Author(s):  
Hermann Brenner ◽  
Sabine Kuznia ◽  
Clarissa Laetsch ◽  
Tobias Niedermaier ◽  
Ben Schöttker

Meta-analyses of randomized controlled trials (RCTs) have demonstrated a protective effect of vitamin D3 (cholecalciferol) supplementation against cancer mortality. In the VITAL study, a RCT including 25,871 men ≥ 50 years and women ≥ 55 years, protective effects of vitamin D3 supplementation (2000 IU/day over a median of 5.3 years) with respect to incidence of any cancer and of advanced cancer (metastatic cancer or cancer death) were seen for normal-weight participants but not for overweight or obese participants. We aimed to explore potential reasons for this apparent variation of vitamin D effects by body mass index. We conducted complementary analyses of published data from the VITAL study on the association of body weight with cancer outcomes, stratified by vitamin D3 supplementation. Significantly increased risks of any cancer and of advanced cancer were seen among normal-weight participants compared to obese participants in the control group (relative risk (RR), 1.27; 95% confidence interval (CI), 1.07–1.52, and RR, 1.44; 95% CI, 1.04–1.97, respectively). No such patterns were seen in the intervention group. Among those with incident cancer, vitamin D3 supplementation was associated with a significantly reduced risk of advanced cancer (RR, 0.86; 95% CI, 0.74–0.99). The observed patterns point to pre-diagnostic weight loss of cancer patients and preventive effects of vitamin D3 supplementation from cancer progression as plausible explanations for the body mass index (BMI)—intervention interactions. Further research, including RCTs more comprehensively exploring the potential of adjuvant vitamin D therapy for cancer patients, should be pursued with priority.


Author(s):  
Maryam Mosavat ◽  
Aisling Smyth ◽  
Diana Arabiat ◽  
Lisa Whitehead

AbstractVitamin D contributes to numerous physiological processes within the body but primarily calcium and bone homeostasis. Emerging evidence highlights a novel role for vitamin D in maintaining and regulating optimal sleep. Sleep is a known regulator of bone health, highlighting the interconnectedness between vitamin D concentrations, sleep duration and bone metabolism. It is possible that the relationship between sleep length and vitamin D is bidirectional, with vitamin D playing a role in sleep health and conversely, sleep affecting vitamin D levels. Nevertheless, limited information on the direction of the interaction is available, and much remains to be learned concerning the complex relationship between insufficient sleep duration and vitamin D deficiency. Given the potential to implement interventions to improve sleep and vitamin D supplementation, understanding this relationship further could represent a novel way to support and improve health.


2021 ◽  
Vol 22 (10) ◽  
pp. 5251
Author(s):  
Ming-Yieh Peng ◽  
Wen-Chih Liu ◽  
Jing-Quan Zheng ◽  
Chien-Lin Lu ◽  
Yi-Chou Hou ◽  
...  

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is still an ongoing global health crisis. Immediately after the inhalation of SARS-CoV-2 viral particles, alveolar type II epithelial cells harbor and initiate local innate immunity. These particles can infect circulating macrophages, which then present the coronavirus antigens to T cells. Subsequently, the activation and differentiation of various types of T cells, as well as uncontrollable cytokine release (also known as cytokine storms), result in tissue destruction and amplification of the immune response. Vitamin D enhances the innate immunity required for combating COVID-19 by activating toll-like receptor 2. It also enhances antimicrobial peptide synthesis, such as through the promotion of the expression and secretion of cathelicidin and β-defensin; promotes autophagy through autophagosome formation; and increases the synthesis of lysosomal degradation enzymes within macrophages. Regarding adaptive immunity, vitamin D enhances CD4+ T cells, suppresses T helper 17 cells, and promotes the production of virus-specific antibodies by activating T cell-dependent B cells. Moreover, vitamin D attenuates the release of pro-inflammatory cytokines by CD4+ T cells through nuclear factor κB signaling, thereby inhibiting the development of a cytokine storm. SARS-CoV-2 enters cells after its spike proteins are bound to angiotensin-converting enzyme 2 (ACE2) receptors. Vitamin D increases the bioavailability and expression of ACE2, which may be responsible for trapping and inactivating the virus. Activation of the renin–angiotensin–aldosterone system (RAS) is responsible for tissue destruction, inflammation, and organ failure related to SARS-CoV-2. Vitamin D inhibits renin expression and serves as a negative RAS regulator. In conclusion, vitamin D defends the body against SARS-CoV-2 through a novel complex mechanism that operates through interactions between the activation of both innate and adaptive immunity, ACE2 expression, and inhibition of the RAS system. Multiple observation studies have shown that serum concentrations of 25 hydroxyvitamin D are inversely correlated with the incidence or severity of COVID-19. The evidence gathered thus far, generally meets Hill’s causality criteria in a biological system, although experimental verification is not sufficient. We speculated that adequate vitamin D supplementation may be essential for mitigating the progression and severity of COVID-19. Future studies are warranted to determine the dosage and effectiveness of vitamin D supplementation among different populations of individuals with COVID-19.


Author(s):  
Matthew F Warren ◽  
Kimberly A Livingston

Abstract The risk of vitamin D insufficiency in humans is a global problem that requires improving ways to increase vitamin D intake. Supplements are a primary means for increasing vitamin D intake, but without a clear consensus on what constitutes vitamin D sufficiency, there is toxicity risk with taking supplements. Chickens have been used in many vitamin D-related research studies, especially studies involving vitamin D supplementation. Our state-of-the-art review evaluates vitamin D metabolism and how the different hydroxylated forms are synthesized. We provide an overview with how vitamin D is absorbed, transported, excreted, and what tissues in the body store vitamin D metabolites. We also discuss a number of studies involving vitamin D supplementation with broilers and laying hens. Vitamin D deficiency and toxicity are also described and how they can be caused. The vitamin D receptor (VDR) is important for vitamin D metabolism. However, there is much more that can be understood with VDR in chickens. Potential research aims involving vitamin D and chickens should explore VDR mechanisms which could lead to newer insights with VDR. Utilizing chickens in future research to help with elucidating vitamin D mechanisms has great potential to advance human nutrition. Finding ways to increase vitamin D intake will be necessary because the coronavirus 2019 disease (COVID-19) pandemic is leading to increased risk of vitamin D deficiency in many populations. Chickens can provide a dual purpose with addressing pandemic-caused vitamin D deficiency: 1) vitamin D supplementation gives chickens added value with possibly leading to vitamin D-enriched meat and egg products; and 2) chickens’ use in research provides data for translational research. Expanding vitamin D-related research in chickens to include more nutritional aims in vitamin D status has great implications with developing better strategies to improve human health.


Author(s):  
Marius Baranauskas ◽  
Valerija Jablonskienė ◽  
Jonas Algis Abaravičius ◽  
Rimantas Stukas

There are about 466 million people with hearing impairments in the world. The scientific literature does not provide sufficient data on the actual nutrition and other variables of professional deaf athletes. The objectives of this study were to investigate and evaluate the body composition, the physical working capacity, the nutrition intake, and the blood parameters of iron and vitamin D in the Lithuanian high-performance deaf women’s basketball team players. The female athletes (n = 14) of the Lithuanian deaf basketball team aged 26.4 ± 4.5 years were recruited for an observational cross-sectional study. A 7-day food recall survey method was used to investigate their actual diet. The measurements of the body composition were performed using the BIA (bioelectrical impedance analysis) tetra-polar electrodes. In order to assess the cardiorespiratory and aerobic fitness levels of athletes, ergo-spirometry (on a cycle ergometer) was used to measure the peak oxygen uptake (VO2peak) and the physical working capacity at a heart rate of 170 beats per minute (PWC170). The athletes’ blood tests were taken to investigate the red blood cells, hemoglobin, 25-hydroxyvitamin D, ferritin, transferrin, iron concentrations, and total iron-binding capacity (TIBC). The consideration of the VO2peak (55.9 ± 6.1 mL/min/kg of body weight, 95% CI: 51.8, 58.9) and the low VO2peak (56–60 mL/min/kg of body weight) (p = 0.966) in the deaf women’s basketball team players revealed no differences. For the deaf female athletes, the PWC170 was equal to 20.3 ± 2.0 kgm/min/kg of body weight and represented only the average aerobic fitness level. The carbohydrate and protein intakes (5.0 ± 1.3 and 1.3 ± 0.3 g/kg of body weight, respectively) met only the minimum levels recommended for athletes. The fat content of the diet (38.1 ± 4.1% of energy intake) exceeded the maximum recommended content (35% of energy intake) (p = 0.012). The mean blood serum concentrations of 25(OH)D and ferritin (24.1 ± 6.6 nmol/L and 11.0 ± 4.1 µg/L, respectively) predicted vitamin D and iron deficits in athletes. Female athletes had an increased risk of vitamin D and iron deficiencies. Regardless of iron deficiency in the body, the better cardiorespiratory fitness of the deaf female athletes was essentially correlated with the higher skeletal muscle mass (in terms of size) (r = 0.61, p = 0.023), the lower percentage of body fat mass (r = −0.53, p = 0.049), and the reduced intake of fat (r = −0.57, p = 0.040).


2013 ◽  
Vol 14 (3) ◽  
pp. 406-414 ◽  
Author(s):  
Hinemoa Elder

Background: International research identifies indigeneity as a risk factor for traumatic brain injury (TBI). Aotearoa New Zealand studies show that mokopuna (grandchildren; used here to encompass the ages and stages of infant, child and adolescent development and those in young adulthood) are significantly overrepresented in TBI populations. The important role of whānau (family) is also well established in child and adolescent TBI scholarship. Despite awareness of these factors, no studies have been identified that explore whānau knowledge about mokopuna TBI. The aim of this study was to explore two questions: (1) What do Māori people say about mokopuna TBI in the context of the Māori cultural belief that the head is the most sacred part of the body? and (2) How could this information be used to build theory that could inform addressing the rehabilitation needs of this group?Method: Eighteen marae wānanga (culture-specific fora in traditional meeting houses) were held. The wānanga typically lasted approximately 2 hours. Footage and written transcripts were analysed using Rangahau Kaupapa Māori (Māori indigenous research methods).Results: The wairua theory of mokopuna TBI proposes that TBI not only injures brain anatomy and physiology but also injures wairua (defined here as a unique connection between Māori and all aspects of the universe). Injury to wairua means that culturally determined interventions are both indicated and expected. The wairua theory of mokopuna TBI thereby provides a guide to intervention.Conclusion: A Māori theory of mokopuna TBI has been identified which describes a culture-specific aspect of TBI. This theory proposes that pre-existing whānau knowledge salient to TBI is critical to optimising recovery. Further research is needed to test this theory not only in TBI but also in other areas such as in mental illness, neurodegenerative disease and addiction.


Author(s):  
Katarzyna Zadka ◽  
Ewelina Pałkowska-Goździk ◽  
Danuta Rosołowska-Huszcz

The percentage of children with vitamin D deficiency in Poland is alarming. The aim of the study was to assess the knowledge about sources of food and the function of vitamin D, as well as the frequency of its supplementation. A survey was conducted among the parents of children from Central Poland attending primary schools, and a questionnaire containing mainly open-ended questions was used to collect the data. Most mothers knew at least one of the functions of vitamin D in the body but had a low level of knowledge about its dietary sources. Only a small group of respondents supplemented themselves and their children with vitamin D. Statistically significant influences on the level of knowledge about the functions and sources of vitamin D were place of residence (i.e., better knowledge in the countryside) and mothers’ level of education (i.e., the better educated, the greater knowledge). In the case of monthly income level, such impact was observed only in relation to the knowledge of vitamin D functions. Concerning the frequency of supplementation, only maternal level of education had a statistically significant effect (i.e., the higher the education level, the higher the frequency of supplementation). In addition, mothers who were aware of functions of vitamin D and nutritional sources, significantly more frequently supplemented vitamin D.


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