Editing Human body (section)

==Composition==
{{Main|Composition of the human body}}
{| class="wikitable floatright"  style="font-size: 86%"
|+  align="bottom" style="text-align:left; caption-side: bottom" | Elements of the human body by mass. [[Trace element|Trace elements]] are less than 1% combined (and each less than 0.1%).
| rowspan="13"|[[File:201 Elements of the Human Body.02.svg|300px]]
| style="width: 50pt;"| '''Element'''
| style="width: 10pt; text-align:center;"|'''Symbol'''
| style="width: 20pt; text-align:center;"| '''Percent mass'''
| style="width: 20pt; text-align:center;"| '''Percent atoms'''
|-
| Oxygen
| style="text-align:center;"|O
| style="text-align:right;"|65.0
| style="text-align:right;"|24.0
|-
| Carbon
| style="text-align:center;"|C
| style="text-align:right;"|18.5
| style="text-align:right;"|12.0
|-
| Hydrogen
| style="text-align:center;"|H
| style="text-align:right;"|9.5
| style="text-align:right;"|62.0
|-
| Nitrogen
| style="text-align:center;"|N
| style="text-align:right;"|3.2
| style="text-align:right;"|1.1
|-
| Calcium
| style="text-align:center;"|Ca
| style="text-align:right;"|1.5
| style="text-align:right;"|0.22
|-
| Phosphorus
| style="text-align:center;"|P
| style="text-align:right;"|1.0
| style="text-align:right;"|0.22
|-
| Potassium
| style="text-align:center;"|K
| style="text-align:right;"|0.4
| style="text-align:right;"|0.03
|-
| Sulfur
| style="text-align:center;"|S
| style="text-align:right;"|0.3
| style="text-align:right;"|0.038
|-
| Sodium
| style="text-align:center;"|Na
| style="text-align:right;"|0.2
| style="text-align:right;"|0.037
|-
| Chlorine
| style="text-align:center;"|Cl
| style="text-align:right;"|0.2
| style="text-align:right;"|0.024
|-
| Magnesium
| style="text-align:center;"|Mg
| style="text-align:right;"|0.1
| style="text-align:right;"|0.015
|-
|  Trace elements
|
| style="text-align:right;"|< 0.1
| style="text-align:right;"|< 0.3
|}

The [[composition of the human body|human body is composed of]] [[chemical element|elements]] including [[hydrogen]], [[oxygen]], [[carbon]], [[calcium]] and [[phosphorus]]. These elements reside in trillions of cells and non-cellular components of the body.

The adult male body is about 60% [[Body water|total body water]] content of some {{convert|42|litre}}. This is made up of about {{convert|19|litres}} of [[extracellular fluid]] including about {{convert|3.2|litre}} of [[blood plasma]] and about {{convert|8.4|litre}} of [[Extracellular fluid|interstitial fluid]], and about {{convert|23|litre}} of fluid inside cells.<ref>{{Cite web|title=Fluid Physiology|url=http://www.anaesthesiamcq.com/FluidBook/fl2_1.php|website=Anaesthesiamcq|url-status=dead|archive-url=https://web.archive.org/web/20050503083706/http://www.anaesthesiamcq.com/FluidBook/fl2_1.php|archive-date=3 May 2005|access-date=2 September 2016}}</ref> The content, [[pH|acidity]] and composition of the water inside and outside cells is carefully maintained. The main [[electrolyte]]s in body water outside cells are [[sodium]] and [[chloride]], whereas within cells it is [[potassium]] and other [[phosphate]]s.{{sfn|Ganong's|2016|p=5}}

===Cells===
{{See also|List of distinct cell types in the adult human body}}
The body contains trillions of [[Cell (biology)|cells]], the fundamental unit of life. At maturity, there are roughly 30 trillion cells, and 38 trillion bacteria in the body,<ref name="sender-et-al">{{Cite journal |last1=Sender |first1=Ron |last2=Fuchs |first2=Shai |last3=Milo |first3=Ron |year=2016 |title=Revised estimates for the number of human and bacteria cells in the body |journal=PLOS Biology |volume=14 |issue=8 |pages=e1002533 |biorxiv=10.1101/036103 |doi=10.1371/journal.pbio.1002533 |pmc=4991899 |pmid=27541692 |doi-access=free |issn = 1544-9173}}</ref><ref>{{Cite journal |last1=Hatton |first1=Ian A. |last2=Galbraith |first2=Eric D. |last3=Merleau |first3=Nono S. C. |last4=Miettinen |first4=Teemu P. |last5=Smith |first5=Benjamin McDonald |last6=Shander |first6=Jeffery A. |date=2023-09-26 |title=The human cell count and size distribution |journal=Proceedings of the National Academy of Sciences |language=en |volume=120 |issue=39 |pages=e2303077120 |doi=10.1073/pnas.2303077120 |doi-access=free |issn=0027-8424 |pmc=10523466 |pmid=37722043|bibcode=2023PNAS..12003077H }}</ref> an estimate arrived at by totaling the cell numbers of all the [[Organ (biology)|organs]] of the body and [[List of human cell types|cell types]]. The skin of the body is also host to billions of commensal organisms as well as immune cells.<ref name="Sfriso">{{cite journal |last1=Sfriso |first1=R |last2=Egert |first2=M |last3=Gempeler |first3=M |last4=Voegeli |first4=R |last5=Campiche |first5=R |title=Revealing the secret life of skin - with the microbiome you never walk alone. |journal=International Journal of Cosmetic Science |date=April 2020 |volume=42 |issue=2 |pages=116–126 |doi=10.1111/ics.12594 |pmid=31743445|pmc=7155096 }}</ref>  Not all parts of the body are made from cells. Cells sit in an [[extracellular matrix]] that consists of [[protein]]s such as [[collagen]], surrounded by extracellular fluids.

Each of the cells of the human body experiences, on average, tens of thousands of [[DNA damage (naturally occurring)|DNA damages]] per day.<ref name = Jackson2009>{{cite journal |vauthors=Jackson SP, Bartek J |title=The DNA-damage response in human biology and disease |journal=Nature |volume=461 |issue=7267 |pages=1071–8 |date=October 2009 |pmid=19847258 |pmc=2906700 |doi=10.1038/nature08467 |bibcode=2009Natur.461.1071J |url=}}</ref>  These damages can block [[human genome|genome]] replication or genome transcription, and if they are not [[DNA repair|repaired]] or are repaired incorrectly, they may lead to [[mutation]]s, or other genome alterations that threaten cell viability.<ref name = Jackson2009/> 

====Genome====
{{Main|Genome}}
{{See also|Genetics}}
[[File:Genome-fr.svg|thumb|[[Genome]]]]
Cells in the body function because of [[DNA]]. DNA sits within the [[Cell nucleus|nucleus of a cell]]. Here, parts of DNA are [[Transcription (biology)|copied]] and sent to the body of the cell via [[RNA]].{{sfn|Ganong's|2016|p=16}} The RNA is then used to [[translation (biology)|create]] [[protein]]s, which form the basis for cells, their activity, and their products. Proteins dictate cell function and gene expression, a cell is able to self-regulate by the amount of proteins produced.<ref>{{Cite web|title=Gene Expression {{!}} Learn Science at Scitable|url=http://www.nature.com/scitable/topicpage/gene-expression-14121669|website=www.nature.com|language=en|url-status=dead|archive-url=https://web.archive.org/web/20101031053632/http://www.nature.com/scitable/topicpage/gene-expression-14121669|archive-date=31 October 2010|access-date=29 July 2017}}</ref> However, not all cells have DNA; some cells such as mature [[Red blood cell|red blood cells]] lose their nucleus as they mature.

===Tissues===
[[File:DIagram of the different types of soft tissue in the body CRUK 037.svg|thumb|Diagram of the different types of [[soft tissue]] in the body]]
The body consists of many different types of [[Tissue (biology)|tissue]], defined as cells that act with a specialised function.<ref>{{Cite web |url=https://en.oxforddictionaries.com/definition/tissue |archive-url=https://web.archive.org/web/20161005004435/https://en.oxforddictionaries.com/definition/tissue |url-status=dead |archive-date=5 October 2016 |title=tissue – definition of tissue in English |work=[[Oxford Dictionaries (website)|Oxford Dictionaries]]{{!}} English |access-date=17 September 2016}}</ref> The study of tissues is called [[histology]] and is often done with a [[microscope]]. The body consists of four main types of tissues. These are lining cells ([[Epithelium|epithelia]]), [[connective tissue]], [[Nervous tissue|nerve tissue]] and [[Muscle|muscle tissue]].{{sfn|Gray's Anatomy|2008|p=27}}

====Cells====
Cells that line surfaces exposed to the outside world or gastrointestinal tract ([[Epithelium|epithelia]]) or internal cavities ([[endothelium]]) come in numerous shapes and forms – from [[Epithelium|single layers of flat cells]], to cells with small beating hair-like [[Cilium|cilia]] in the lungs, to column-like cells that line the [[stomach]]. Endothelial cells are cells that line internal cavities including blood vessels and glands. Lining cells regulate what can and cannot pass through them, protect internal structures, and function as sensory surfaces.{{sfn|Gray's Anatomy|2008|p=27}}

===Organs===
{{See also|List of organs of the human body}}
[[File:Internal Organs of the Human Body from The Household Physician, 1905 (6404030777).jpg|thumb|1905 diagram of the internal organs of the human body]]

[[Organ (biology)|Organs]], structured collections of [[Cell (biology)|cells]] with a specific function,<ref>{{Cite web |url=http://www.collinsdictionary.com/dictionary/english/organ |title=organ {{!}} Definition, meaning & more |publisher=[[Collins Dictionary]] |website=www.collinsdictionary.com |access-date=17 September 2016}}</ref> mostly sit within the body, with the exception of [[Human skin|skin]]. Examples include the [[heart]], [[lung]]s and [[liver]]. Many organs reside within [[Body cavity|cavities]] within the body. These cavities include the [[abdominopelvic cavity|abdomen]] (which contains the stomach, for example) and [[pleural cavity|pleura]], which contains the lungs.

==== Heart ====
{{Main|Heart}}
The heart is an organ located in the [[thoracic cavity]] between the [[lung]]s and slightly to the left. It is surrounded by the [[pericardium]], which holds it in place in the [[mediastinum]] and serves to protect it from blunt trauma, [[infection]] and help lubricate the movement of the heart via [[pericardial fluid]].<ref>{{Cite journal|last1=Jaworska-Wilczynska|first1=Maria|last2=Trzaskoma|first2=Pawel|last3=Szczepankiewicz|first3=Andrzej A.|last4=Hryniewiecki|first4=Tomasz|date=2016|title=Pericardium: structure and function in health and disease|journal=Folia Histochemica et Cytobiologica|volume=54|issue=3|pages=121–125|doi=10.5603/FHC.a2016.0014|issn=1897-5631|pmid=27654013|doi-access=free}}</ref> The heart works by [[Circulatory system|pumping blood around the body]] allowing [[oxygen]], [[nutrient]]s, [[Metabolic waste|waste]], [[hormone]]s and [[white blood cell]]s to be transported.
[[File:Diagram of the human heart (cropped).svg|left|thumb|207x207px|Diagram of the human heart]]
The heart is composed of [[Atrium (heart)|two atria]] and [[Ventricle (heart)|two ventricles]]. The primary purpose of the atria is to allow uninterrupted venous blood flow to the heart during [[Systole|ventricular systole]]. This allows enough blood to get into the ventricles during [[Systole|atrial systole]]. Consequently, the atria allows a [[cardiac output]] roughly 75% greater than would be possible without them.<ref>{{Cite book|url=https://books.google.com/books?id=A3OmTSgtOgwC|title=The Gross Physiology of the Cardiovascular System|date=1999|first=Robert M. |last=Anderson|edition=2nd |chapter=Chapter 1: Normal Physiology |page=11}}</ref> The purpose of the ventricles is to [[Pulmonary circulation|pump blood to the lungs]] through the right ventricle and to [[Circulatory system|the rest of the body]] through the left ventricle.<ref>{{Cite web|title=Ventricle {{!}} heart|url=https://www.britannica.com/science/ventricle-heart|access-date=2021-08-07|website=Encyclopedia Britannica|language=en}}</ref>

The heart has an [[Cardiac conduction system|electrical conduction system]] to control the contraction and relaxation of the muscles. It starts in the [[sinoatrial node]] traveling through the atria causing them to [[Cardiac cycle|pump blood into the ventricles]]. It then travels to the [[atrioventricular node]], which makes the signal slow down slightly allowing the ventricles to fill with blood before pumping it out and starting the cycle over again.<ref>{{Cite web|title=How the Heart Works |url=https://www.nhlbi.nih.gov/health-topics/how-heart-works|access-date=2021-08-07|website=NHLBI, NIH |at="Your Heart's Electrical System" |url-status=live |archive-url= https://web.archive.org/web/20210813001819/https://www.nhlbi.nih.gov/health-topics/how-heart-works |archive-date= Aug 13, 2021 }}</ref>

[[Coronary artery disease]] is the [[List of causes of death by rate|leading cause of death worldwide]], making up 16% of all deaths.<ref>{{Cite web|title=The top 10 causes of death|url=https://www.who.int/news-room/fact-sheets/detail/the-top-10-causes-of-death |date=9 December 2020 |access-date=2021-08-07|website=WHO |language=en}}</ref> It is caused by the buildup of [[Atherosclerosis|plaque]] in the [[coronary arteries]] supplying the heart, eventually the arteries may become so narrow that [[Ischemia|not enough blood]] is able to reach the [[Cardiac muscle|myocardium]],<ref>{{Cite web|date=2021-07-19|title=Coronary Artery Disease |url=https://www.cdc.gov/heartdisease/coronary_ad.htm|access-date=2021-08-07|website=Centers for Disease Control and Prevention|language=en-us}}</ref> a condition known as [[Myocardial infarction|myocardial infarction or heart attack]], this can cause [[heart failure]] or [[cardiac arrest]] and eventually death.<ref>{{Cite web|date=2021-01-11|title=Heart Attack Symptoms, Risk Factors, and Recovery |url=https://www.cdc.gov/heartdisease/heart_attack.htm|access-date=2021-08-07|website=Centers for Disease Control and Prevention|language=en-us}}</ref> Risk factors for coronary artery disease include [[Obesity-associated morbidity|obesity]], [[Health effects of tobacco|smoking]], [[Hypercholesterolemia|high cholesterol]], [[Hypertension|high blood pressure]], [[Sedentary lifestyle|lack of exercise]] and [[diabetes]].<ref>{{Cite web|date=2019-12-09|title=Know Your Risk for Heart Disease |url=https://www.cdc.gov/heartdisease/risk_factors.htm|access-date=2021-08-07|website=Centers for Disease Control and Prevention|language=en-us}}</ref> [[Heart cancer|Cancer can affect the heart]], though it is exceedingly rare and has usually [[Metastasis|metastasized]] from another part of the body such as the [[Lung cancer|lungs]] or [[Breast cancer|breasts]]. This is because the [[Cardiac muscle|heart cells]] quickly stop dividing and all growth occurs through [[Hypertrophy|size increase]] rather than [[Mitosis|cell division]].<ref>{{Cite web|date=2009-02-10|title=Matters of the Heart: Why Are Cardiac Tumors So Rare? |url=https://www.cancer.gov/types/metastatic-cancer/research/cardiac-tumors|access-date=2021-08-07|website= National Cancer Institute|language=en}}</ref>

==== Gallbladder ====
{{Main|Gallbladder}}
[[File:2425 Gallbladder.jpg|thumb|[[Gallbladder]]]]
The gallbladder is a hollow pear-shaped organ located [[Anatomical terms of location|posterior]] to the [[Anatomical terms of location|inferior]] middle part of the [[Lobes of liver|right lobe of the liver]]. It is variable in shape and size. It stores [[bile]] before it is released into the small intestine via the [[common bile duct]] to help with [[Lipid metabolism|digestion of fats]]. It receives bile from the [[liver]] via the [[cystic duct]], which connects to the [[common hepatic duct]] to form the [[common bile duct]].<ref name="Nagral2005">{{cite journal|last1=Nagral|first1=Sanjay|title=Anatomy relevant to cholecystectomy|journal=Journal of Minimal Access Surgery|date=2005|volume=1|issue=2|pages=53–8|doi=10.4103/0972-9941.16527|pmid=21206646|pmc=3004105 |doi-access=free }}</ref>

The gallbladder gets its blood supply from the [[cystic artery]], which in most people, emerges from the [[Hepatic artery proper|right hepatic artery]].<ref name="Nagral2005" />

[[Gallstone]]s is a common disease in which one or more stones form in the gallbladder or [[biliary tract]]. Most people are asymptomatic but if a stone blocks the biliary tract, it causes a [[Biliary colic|gallbladder attack]], symptoms may include sudden pain in the upper right abdomen or center of the abdomen. Nausea and vomiting may also occur. Typical treatment is removal of the gallbladder through a procedure called a [[cholecystectomy]].<ref>{{Cite web|title=Gallstones – Symptoms and causes|url=https://www.mayoclinic.org/diseases-conditions/gallstones/symptoms-causes/syc-20354214|access-date=2021-08-07|website=Mayo Clinic|language=en}}</ref><ref>{{Cite web|title=Gallstones – Diagnosis and treatment |url=https://www.mayoclinic.org/diseases-conditions/gallstones/diagnosis-treatment/drc-20354220|access-date=2021-08-07|website=www.mayoclinic.org}}</ref> Having gallstones is a risk factor for [[gallbladder cancer]], which although quite uncommon, is rapidly fatal if not diagnosed early.<ref>{{Cite web|title=Gallbladder cancer – Symptoms and causes|url=https://www.mayoclinic.org/diseases-conditions/gallbladder-cancer/symptoms-causes/syc-20353370|access-date=2021-08-07|website=Mayo Clinic|language=en}}</ref>

===Systems===
{{See also|List of systems of the human body}}
<!--
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File:Organ Systems I.jpg
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==== Circulatory system ====
{{Main|Circulatory system}}
[[File:Diagram showing the circulatory system of the body CRUK 299.svg|thumb|Diagram showing the [[circulatory system]] of the body]]
The [[circulatory system]] consists of the [[heart]] and [[blood vessel]]s ([[Artery|arteries]], [[vein]]s and [[Capillary|capillaries]]). The heart propels the circulation of the blood, which serves as a "transportation system" to transfer [[oxygen]], fuel, nutrients, waste products, immune cells and signaling molecules (i.e. [[Hormone|hormones]]) from one part of the body to another. Paths of blood circulation within the human body can be divided into two circuits: the [[Pulmonary circulation|pulmonary circuit]], which pumps blood to the lungs to receive [[oxygen]] and leave [[carbon dioxide]], and the systemic circuit, which carries blood from the heart off to the rest of the body. The blood consists of fluid that carries [[Cell (biology)|cells]] in the circulation, including some that move from tissue to blood vessels and back, as well as the [[spleen]] and [[bone marrow]].<ref>{{Cite news|title=Cardiovascular System|publisher=[[U.S. National Cancer Institute]]|url=http://training.seer.cancer.gov/module_anatomy/unit7_1_cardvasc_intro.html|url-status=dead|access-date=16 September 2008|archive-url=https://web.archive.org/web/20070202040248/http://www.training.seer.cancer.gov/module_anatomy/unit7_1_cardvasc_intro.html|archive-date=2 February 2007}}</ref><ref>{{Cite book |url=https://archive.org/details/humanbiologyheal00scho |title=Human Biology and Health |publisher=[[Pearson Prentice Hall]] |year=1993 |isbn=0-13-981176-1 |location=Upper Saddle River, NJ}}</ref><ref>{{Cite web |url=http://ect.downstate.edu/courseware/histomanual/cardiovascular.html |title=The Cardiovascular System |date=8 March 2008 |publisher=[[State University of New York]] Downstate Medical Center |access-date=16 September 2008 |archive-date=11 June 2016 |archive-url=https://web.archive.org/web/20160611213345/http://ect.downstate.edu/courseware/histomanual/cardiovascular.html |url-status=dead }}</ref>

==== Digestive system ====
{{Main|Digestive system}}
[[File:Digestive system diagram en.svg|left|thumb|Digestive system]]
The [[Human digestive system|digestive system]] consists of the mouth including the [[tongue]] and [[Human tooth|teeth]], [[esophagus]], [[stomach]], ([[gastrointestinal tract]], [[small intestine|small]] and [[large intestine]]s, and [[rectum]]), as well as the [[liver]], [[pancreas]], [[gallbladder]], and [[salivary gland]]s. It converts food into small, nutritional, non-toxic [[molecule]]s for distribution and absorption into the body. These molecules take the form of [[protein]]s (which are broken down into [[amino acid]]s), [[fat]]s, [[vitamin]]s and [[Mineral (nutrient)|minerals]] (the last of which are mainly ionic rather than molecular). After being [[Swallowing|swallowed]], food moves through the [[gastrointestinal tract]] by means of [[peristalsis]]: the systematic expansion and contraction of muscles to push food from one area to the next.<ref>{{Cite web |url=https://www.niddk.nih.gov/health-information/health-topics/Anatomy/your-digestive-system/Pages/anatomy.aspx |title=Your Digestive System and How It Works |publisher=[[National Institute of Health]] |access-date=4 September 2016}}</ref><ref name="niddk.nih.gov">{{cite web |url=https://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works |title=Your Digestive System & How it Works |publisher=[[National Institute of Diabetes and Digestive and Kidney Diseases]] |access-date=29 June 2019}}</ref>

Digestion begins in the [[Human mouth|mouth]], which [[Chewing|chews]] food into smaller pieces for easier digestion. Then it is [[Swallowing|swallowed]], and moves through the [[esophagus]] to the [[stomach]]. In the stomach, food is mixed with [[gastric acid]]s to allow the extraction of [[nutrient]]s. What is left is called [[chyme]]; this then moves into the [[small intestine]], which absorbs the nutrients and water from the chyme. What remains passes on to the [[large intestine]], where it is dried to form [[Human feces|feces]]; these are then stored in the [[rectum]] until they are expelled through the [[Human anus|anus]].<ref name="niddk.nih.gov" />

==== Endocrine system ====
{{Main|Endocrine system}}
[[File:Endocrine English.svg|thumb|[[Endocrine system]]]]
The [[endocrine system]] consists of the principal [[endocrine gland]]s: the [[Pituitary gland|pituitary]], [[thyroid]], [[Adrenal gland|adrenals]], [[pancreas]], [[Parathyroid gland|parathyroids]], and [[gonad]]s, but nearly all organs and tissues produce specific endocrine [[hormone]]s as well. The endocrine hormones serve as signals from one body system to another regarding an enormous array of conditions, resulting in variety of changes of function.<ref>{{cite web|title=Hormonal (endocrine) system|url=https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/hormonal-endocrine-system |publisher=[[Victoria State Government]]|access-date=4 September 2016}}</ref>

==== Immune system ====
{{Main|Immune system}}
[[File:Primary immune response 1.png|thumb|Primary immune response]]
The [[immune system]] consists of the [[white blood cell]]s, the [[thymus]], [[lymph node]]s and [[lymph]] channels, which are also part of the [[lymphatic system]]. The immune system provides a mechanism for the body to distinguish its own cells and tissues from outside cells and substances and to neutralize or destroy the latter by using specialized proteins such as [[Antibody|antibodies]], [[Cytokine|cytokines]], and [[Toll-like receptor|toll-like receptors]], among many others.<ref>{{cite web|last1=Zimmermann|first1=Kim Ann|title=Immune System: Diseases, Disorders & Function|url=http://www.livescience.com/26579-immune-system.html|publisher=[[LiveScience]]|access-date=4 September 2016}}</ref>
[[File:Skin layers.svg|thumb|236x236px|Skin]]

==== Integumentary system ====
{{Main|Integumentary system}}

The [[integumentary system]] consists of the covering of the body (the [[human skin|skin]]), including hair and [[nail (anatomy)|nails]] as well as other functionally important structures such as the [[sweat gland]]s and [[sebaceous gland]]s. The skin provides containment, structure, and protection for other organs, and serves as a major sensory interface with the outside world.<ref>{{MeSH name|Integumentary+System}}</ref><ref>{{cite book | last1=Marieb | first1=Elaine |author-link=Elaine Nicpon Marieb |last2=Hoehn |first2=Katja | title=Human Anatomy & Physiology | url=https://archive.org/details/humananatomyphys00mari_4 | url-access=registration | publisher=Pearson Benjamin Cummings | year=2007 | edition=7th | page=[https://archive.org/details/humananatomyphys00mari_4/page/142 142]| isbn=978-0805359107 }}</ref>

==== Lymphatic system ====
{{Main|Lymphatic system}}
[[File:Blausen 0623 LymphaticSystem Female.png|thumb|[[Lymphatic system]] female]]
The [[lymphatic system]] extracts, transports and metabolizes lymph, the fluid found in between cells. The lymphatic system is similar to the circulatory system in terms of both its structure and its most basic function, to carry a body fluid.<ref>{{cite web|last1=Zimmermann|first1=Kim Anne|title=Lymphatic System: Facts, Functions & Diseases|url=http://www.livescience.com/26983-lymphatic-system.html|publisher=LiveScience|access-date=4 September 2016}}</ref>

==== Musculoskeletal system ====
{{Main|Musculoskeletal system}}

The [[Human musculoskeletal system|musculoskeletal system]] consists of the [[human skeleton]] (which includes [[bone]]s, [[ligament]]s, [[tendon]]s, [[Joint|joints]] and [[cartilage]]) and attached [[muscle]]s. It gives the body basic structure and the ability for movement. In addition to their structural role, the larger bones in the body contain [[bone marrow]], the site of production of blood cells. Also, all bones are major storage sites for [[Calcium in biology|calcium]] and [[phosphate]]. This system can be split up into the [[muscular system]] and the [[Human skeleton|skeletal system]].<ref>{{cite book | title=Moore's Clinically Oriented Anatomy | publisher=[[Lippincott Williams & Wilkins]] | last1=Moore |first1=Keith L. |last2=Dalley |first2=Arthur F. |last3=Agur |first3=Anne M. R. | year=2010 | location=Phildadelphia | pages=2–3 | isbn=978-1-60547-652-0}}</ref>

==== Nervous system ====
{{Main|Nervous system}}
[[File:Nervous system diagram.png|thumb|303x303px|Nervous system]]

The [[nervous system]] consists of the body's [[neuron]]s and [[glia]]l cells, which together form the [[Nerve|nerves]], [[Ganglion|ganglia]] and [[Grey matter|gray matter]], which in turn form the [[human brain|brain]] and related structures. The brain is the organ of [[thought]], emotion, [[memory]], and [[sensory processing]]; it serves many aspects of communication and controls various systems and functions. The [[special senses]] consist of [[Visual perception|vision]], [[hearing]], [[taste]], and [[Sense of smell|smell]]. The [[human eye|eyes]], [[ear]]s, [[tongue]], and [[human nose|nose]] gather information about the body's environment.<ref>{{cite encyclopedia |last1=Lagassé |first1=Paul |location=New York Detroit | title=Nervous System | encyclopedia=Columbia Encyclopedia | publisher=[[Columbia University Press]] Sold and distributed by [[Gale Group]] | edition=6th | date=2001 | isbn=978-0-7876-5015-5 | url=https://archive.org/details/columbiaencyclop00laga }}</ref>

From a structural perspective, the [[nervous system]] is typically subdivided into two component parts: the [[central nervous system]] (CNS), composed of the brain and the [[spinal cord]]; and the [[peripheral nervous system]] (PNS), composed of the nerves and [[Ganglion|ganglia]] outside the brain and spinal cord. The CNS is mostly responsible for organizing [[motion]], processing [[Sense|sensory information]], thought, memory, [[cognition]] and other such functions.<ref name="livescience.com">{{Cite news|first1=James |last1=Horton |first2=Alina |last2=Bradford |first3=Kim Ann |last3=Zimmermann|date=2022-03-25|title=Nervous System: Facts, Function & Diseases|url=https://www.livescience.com/22665-nervous-system.html|access-date=2023-02-08|website=livescience.com|language=en}}</ref> It remains a matter of some debate whether the [[central nervous system|CNS]] directly gives rise to [[consciousness]].{{cn|date=May 2023}} The [[peripheral nervous system]] (PNS) is mostly responsible for gathering information with [[sensory neuron]]s and directing body movements with [[motor neuron]]s.<ref name="livescience.com"/>

From a functional perspective, the nervous system is again typically divided into two component parts: the [[somatic nervous system]] (SNS) and the [[autonomic nervous system]] (ANS). The SNS is involved in voluntary functions like [[Speech|speaking]] and [[sense|sensory processes]]. The ANS is involved in involuntary processes, such as [[digestion]] and regulating [[blood pressure]].<ref>{{Cite web|title=Visual Guide to Your Nervous System|url=https://www.webmd.com/brain/ss/slideshow-nervous-system-overview|access-date=2023-02-08|website=WebMD|language=en}}</ref>

The nervous system is subject to many different diseases. In [[epilepsy]], abnormal electrical activity in the brain can cause [[Seizure|seizures]]. In [[multiple sclerosis]], the [[immune system]] attacks the [[myelin|nerve linings]], damaging the nerves' ability to transmit signals. [[ALS|Amyotrophic lateral sclerosis]] (ALS), also known as [[Lou Gehrig]]'s disease, is a [[motor neuron]] disease which gradually reduces movement in patients. There are also many other diseases of the nervous system.<ref name="livescience.com"/><!--and Female?-->

==== Reproductive system ====
{{Main|Human reproductive system}}
[[File:Male and female gonads 1.png|thumb|Male gonad (testes, left) and female gonad ([[Ovary|ovaries]], right)]]
The purpose of the [[human reproductive system|reproductive system]] is to reproduce and nurture the growth of offspring. The functions include the production of germ cells and hormones.<ref name="SEER">{{cite web |title=Introduction to the Reproductive System {{!}} SEER Training |url=https://training.seer.cancer.gov/anatomy/reproductive/ |website=training.seer.cancer.gov |access-date=5 March 2024}}</ref> The [[Sex organ|sex organs]] of the [[male reproductive system]] and the [[female reproductive system]] develops and mature at [[puberty]]. These systems include the internal and external [[Sex organ|genitalia]].

[[File:Scheme female reproductive system-en.svg|thumb|Internal [[gross anatomy]] of the [[female reproductive system]]]]
Female puberty generally occurs between the ages of 9 and 13 and is characterized by [[ovulation]] and [[menstruation]]; the growth of secondary sex characteristics, such as growth of [[pubic hair|pubic]] and [[underarm hair]], [[breast]], [[Uterus|uterine]] and [[vagina]]l growth, widening hips and increased height and weight, also occur during puberty.<ref name=":0">{{Cite web|title=Technical Issues In Reproductive Health|url=http://www.columbia.edu/itc/hs/pubhealth/modules/reproductiveHealth/anatomy.html|access-date=2021-08-07|website=www.columbia.edu}}</ref> Male puberty sees the further development of the [[Human penis|penis]] and [[testicle]]s.<ref>{{Cite web|title=Accessory Glands {{!}} SEER Training|url=https://www.training.seer.cancer.gov/anatomy/reproductive/male/glands.html|access-date=2021-08-07|website=www.training.seer.cancer.gov}}</ref>

The female inner sex organs are the two ovaries, their [[fallopian tube]]s, the [[uterus]], and the [[cervix]]. At birth there are about 70,000 [[oocyte|immature egg cells]] that degenerate until at puberty there are around 40,000. No more egg cells are produced. Hormones stimulate the beginning of menstruation, and the ongoing [[menstrual cycle]]s.<ref name=":0" /><ref>{{Cite web|title=Ovaries {{!}} SEER Training|url=https://www.training.seer.cancer.gov/anatomy/reproductive/female/ovaries.html|access-date=2021-08-07|website=www.training.seer.cancer.gov}}</ref> The female external sex organs are the [[vulva]] ([[labia]], [[clitoris]], and [[vulval vestibule|vestibule]]).<ref>{{Cite web|title=External Genitalia {{!}} SEER Training|url=https://www.training.seer.cancer.gov/anatomy/reproductive/female/genitalia.html|access-date=2021-08-07|website=www.training.seer.cancer.gov}}</ref><ref name=":0" />

The male external genitalia include the penis and [[scrotum]] that contains the [[Testicle|testicles]]. The testicles are [[gonad]]s that produce the [[Sperm|sperm cells]] which are [[ejaculation|ejaculated]] in [[semen]] through the penis. Unlike the egg cells in the female, sperm cells are produced throughout life. Other internal sex organs are the [[Epididymis|epididymides]], [[Vas deferens|vasa deferentia]], and some [[Male accessory gland|accessory gland]]s.

Diseases that affect the reproductive system include [[polycystic ovary syndrome]],<ref>{{Cite journal|last1=Ndefo|first1=Uche Anadu|last2=Eaton|first2=Angie|last3=Green|first3=Monica Robinson|date=June 2013|title=Polycystic Ovary Syndrome|journal=Pharmacy and Therapeutics|volume=38|issue=6|pages=336–355|issn=1052-1372|pmc=3737989|pmid=23946629}}</ref> a number of [[Testicle#Disorders and conditions|disorders of the testicles]] including [[testicular torsion]],<ref>{{Cite journal |last=Hyun |first=Grace S. |date=2018 |title=Testicular Torsion |journal=Reviews in Urology |volume=20 |issue=2 |pages=104–106 |doi=10.3909/riu0800 |doi-broken-date=1 November 2024 |issn=1523-6161 |pmc=6168322 |pmid=30288149}}</ref><ref>{{Cite journal|last1=Ringdahl|first1=Erika|last2=Teague|first2=Lynn|date=2006-11-15|title=Testicular torsion|url=https://pubmed.ncbi.nlm.nih.gov/17137004/|journal=American Family Physician|volume=74|issue=10|pages=1739–1743|issn=0002-838X|pmid=17137004}}</ref> and a number of [[sexually transmitted infection]]s including [[syphilis]], [[HIV]], [[chlamydia]], [[Human papillomavirus infection|HPV]] and [[genital wart]]s.<ref>{{Cite web|date=2021-08-02|title=Sexually Transmitted Diseases – Information from CDC|url=https://www.cdc.gov/std/default.htm|access-date=2021-08-07|website=www.cdc.gov|language=en-us}}</ref><ref>{{Cite web|date=2021-06-23|title=CDC – STDs – HPV|url=https://www.cdc.gov/std/hpv/default.htm|access-date=2021-08-07|website=www.cdc.gov|language=en-us}}</ref> [[Cancer]] can affect most parts of the reproductive system including [[Penile cancer|the penis]], [[Testicular cancer|testicles]], [[Prostate cancer|prostate]], [[Ovarian cancer|ovaries]], [[Cervical cancer|cervix]], [[Vaginal cancer|vagina]], [[Fallopian tube cancer|fallopian]], [[Uterine cancer|uterus]] and [[Vulvar cancer|vulva]].<ref>{{Cite web|title=Reproductive Cancers {{!}} HHS Office of Population Affairs|url=https://opa.hhs.gov/reproductive-health/reproductive-cancers|access-date=2021-08-07|website=opa.hhs.gov|language=en}}</ref>

==== Respiratory system ====
{{Main|Respiratory system}}

The [[respiratory system]] consists of the nose, [[Pharynx|nasopharynx]], [[trachea]], and [[Lung|lungs]]. It brings oxygen from the air and excretes [[carbon dioxide]] and water back into the air. First, [[Atmosphere of Earth|air]] is pulled through the trachea into the lungs by the [[thoracic diaphragm|diaphragm]] pushing down, which creates a [[vacuum]]. Air is briefly stored inside small sacs known as [[Pulmonary alveolus|alveoli]] (sing.: alveolus) before being expelled from the lungs when the diaphragm contracts again. Each alveolus is surrounded by [[Capillary|capillaries]] carrying deoxygenated blood, which absorbs oxygen out of the air and into the [[Circulatory system|bloodstream]].<ref>{{cite book |last1=Maton |first1=Anthea|first2=Jean |last2= Hopkins |first3=Susan |last3=Johnson|first4=Charles William |last4= McLaughlin |first5=Maryanna Quon |last5=Warner |first6=David |last6= LaHart |first7=Jill D. |last7=Wright |title=Human Biology and Health |publisher=[[Prentice Hall]] |year=2010 |pages=108–118 |isbn=978-0-13-423435-9}}</ref><ref name="webmd.com">{{Cite web|title=Respiratory System|url=https://www.webmd.com/lung/how-we-breathe|access-date=2023-02-08|website=WebMD|language=en}}</ref>

For the respiratory system to function properly, there need to be as few impediments as possible to the movement of air within the lungs. [[Inflammation]] of the lungs and excess [[mucus]] are common sources of breathing difficulties.<ref name="webmd.com"/> In [[asthma]], the respiratory system is persistently inflamed, causing [[Wheeze|wheezing]] or [[shortness of breath]]. [[Pneumonia]] occurs through [[infection]] of the alveoli, and may be caused by [[tuberculosis]]. [[Chronic obstructive pulmonary disease|Emphysema]], commonly a result of [[smoking]], is caused by damage to connections between the alveoli.<ref>{{Cite web|last=Hoffman|first=Matthew|title=Lung Diseases Overview|url=https://www.webmd.com/lung/lung-diseases-overview|access-date=2023-02-08|website=WebMD|language=en}}</ref>

==== Urinary system ====
{{Main|Urinary system}}
[[File:Urinary System (Female).png|left|thumb|Female [[urinary system]]]]
The [[urinary system]] consists of the two [[kidney]]s, two [[ureter]]s, [[bladder]], and [[urethra]]. It removes<!--excretion--> waste materials from the blood through urine, which carries a variety of waste molecules and excess [[ion]]s and water out of the body.

First, the [[kidney]]s filter the blood through their respective [[nephron]]s, removing [[Metabolic waste|waste products]] like [[urea]], [[creatinine]] and maintaining the [[Electrolyte imbalance|proper balance]] of [[electrolyte]]s and turning the waste products into [[urine]] by combining them with water from the blood.<ref>{{Cite web|title=The Kidneys – a Basic Guide|url=https://www.nhs.uk/Livewell/Kidneyhealth/Documents/kidney%20guide.pdf|url-status=live|archive-url=https://web.archive.org/web/20210109023755/https://www.nhs.uk/Livewell/Kidneyhealth/Documents/kidney%20guide.pdf|archive-date=January 9, 2021|access-date=August 7, 2021|website=[[National Health Service]]}}</ref> The kidneys filter about 150 quarts (170 liters) of blood daily, but most of it is returned to the blood stream with only 1-2 quarts (1-2 liters) ending up as urine,<ref>{{Cite web|title=Your Kidneys & How They Work {{!}} NIDDK|url=https://www.niddk.nih.gov/health-information/kidney-disease/kidneys-how-they-work|access-date=2021-08-07|website=National Institute of Diabetes and Digestive and Kidney Diseases|language=en-US}}</ref> which passes from the kidneys through the [[ureter]]s into the [[bladder]].

The [[smooth muscle]]s lining the ureter walls continuously tighten and relax through a process called [[peristalsis]], forcing small amounts of urine into the bladder every 10–15 seconds.

The bladder is a hollow balloon shaped organ located in the [[pelvis]]. It stores urine until the brain signals it to relax the [[Urethral sphincters|urinary sphincter]] and release the urine into the urethra starting [[urination]].<ref>{{Cite web|title=The Urinary Tract & How It Works {{!}} NIDDK|url=https://www.niddk.nih.gov/health-information/urologic-diseases/urinary-tract-how-it-works|access-date=2021-08-07|website=National Institute of Diabetes and Digestive and Kidney Diseases|language=en-US}}</ref> A normal bladder can hold up to 16 ounces (half a liter) for 3–5 hours comfortably.

Numerous [[Urologic disease|diseases affect the urinary system]] including [[Kidney stone disease|kidney stones]], which are formed when materials in the urine concentrate enough to form a solid mass, [[urinary tract infection]]s, which are infections of the urinary tract and can cause pain when urinating, frequent urination and even death if left untreated. [[Kidney failure|Renal failure]] occurs when the kidneys fail to adequately filter waste from the blood and can lead to death if not treated with [[Kidney dialysis|dialysis]] or [[kidney transplantation]].<ref>{{cite web |last1=Zimmermann |first1=Kim Ann |title=Urinary System: Facts, Functions & Diseases |url=http://www.livescience.com/27012-urinary-system.html |publisher=LiveScience |access-date=4 September 2016}}</ref> [[Cancer]] can affect the [[Bladder cancer|bladder]], [[Kidney cancer|kidneys]], [[Urethral cancer|urethra]] and [[Ureteral cancer|ureters]], with the latter two being far more rare.<ref>{{Cite journal|last=Yaxley|first=Julian P.|date=2016|title=Urinary tract cancers: An overview for general practice|journal=Journal of Family Medicine and Primary Care|volume=5|issue=3|pages=533–538|doi=10.4103/2249-4863.197258|issn=2249-4863|pmc=5290755|pmid=28217578 |doi-access=free }}</ref>