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For the conic sections see Latus rectum or Semi-latus rectum


The rectum (from the Latin rectum intestinum, meaning straight intestine) is the final straight portion of the large intestine
Large intestine

The large intestine is the last part of the digestive system?the final stage of the alimentary canal?in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass this useless feces from the body....
 in some mammal
Mammal

Mammals are a class of vertebrate animals whose name is derived from their distinctive feature, mammary glands, with which they feed their young....
s, and the gut
Gastrointestinal tract

The digestive tract is the system of Organ s within multicellular animals that takes in food, digestion it to extract energy and nutrients, and expels the remaining waste....
 in others, terminating in the anus
Anus

The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to expel feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest, such as coprolite ; food material after all the nutrients have b...
. The human rectum is about 12 cm long. At its commencement its caliber is similar to that of the sigmoid colon
Sigmoid colon

The sigmoid colon forms a loop which averages about 40 cm. in length, and normally lies within the pelvis, but on account of its freedom of movement it is liable to be displaced into the abdominal cavity....
, but near its termination it is dilated, forming the rectal ampulla
Rectal ampulla

The rectal ampulla is the dilated section of the rectum where feces are stored until they are eliminated via the anal canal. The caliber of the rectum at its commencement is similar to that of the sigmoid colon, but near its termination it dilates, forming the ampulla....
.

Role in human defecation
The rectum intestinum acts as a temporary storage facility for feces.






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For the conic sections see Latus rectum or Semi-latus rectum


The rectum (from the Latin rectum intestinum, meaning straight intestine) is the final straight portion of the large intestine
Large intestine

The large intestine is the last part of the digestive system?the final stage of the alimentary canal?in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass this useless feces from the body....
 in some mammal
Mammal

Mammals are a class of vertebrate animals whose name is derived from their distinctive feature, mammary glands, with which they feed their young....
s, and the gut
Gastrointestinal tract

The digestive tract is the system of Organ s within multicellular animals that takes in food, digestion it to extract energy and nutrients, and expels the remaining waste....
 in others, terminating in the anus
Anus

The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to expel feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest, such as coprolite ; food material after all the nutrients have b...
. The human rectum is about 12 cm long. At its commencement its caliber is similar to that of the sigmoid colon
Sigmoid colon

The sigmoid colon forms a loop which averages about 40 cm. in length, and normally lies within the pelvis, but on account of its freedom of movement it is liable to be displaced into the abdominal cavity....
, but near its termination it is dilated, forming the rectal ampulla
Rectal ampulla

The rectal ampulla is the dilated section of the rectum where feces are stored until they are eliminated via the anal canal. The caliber of the rectum at its commencement is similar to that of the sigmoid colon, but near its termination it dilates, forming the ampulla....
.

Role in human defecation


The rectum intestinum acts as a temporary storage facility for feces. As the rectal walls expand due to the materials filling it from within, stretch receptors from the nervous system
Nervous system

The nervous system is a Neural network of specialized cells that communicate information about an animal's surroundings and itself. It processes this information and causes reactions in other parts of the body....
 located in the rectal walls stimulate the desire to defecate
Defecation

Defecation is the final act of digestion by which organisms eliminate solid, semisolid or liquid waste material from the digestive tract via the anus....
. If the urge is not acted upon, the material in the rectum is often returned to the colon
Colon (anatomy)

The colon is the last portion of the digestive system in most vertebrates; it extracts water and salt from feces before they are defecation from the body....
 where more water is absorbed. If defecation is delayed for a prolonged period, constipation
Constipation

Constipation, costiveness, or irregularity, is a condition of the digestive system in which a person experiences hard feces that are difficult to expel....
 and hardened feces results.

When the rectum becomes full the increase in intrarectal pressure forces the walls of the anal canal
Anal canal

The anal canal is the terminal part of the large intestine.It is situated between the rectum and anus, below the level of the pelvic diaphragm....
 apart allowing the fecal matter to enter the canal. The rectum shortens as material is forced into the anal canal and peristaltic wave
Peristalsis

Peristalsis is the rhythmic contraction of smooth muscles to propel contents through the digestive tract. The word is derived from New Latin and comes from the Greek language peristaltikos, peristaltic, from peristellein, "to wrap around," and stellein, "to place."...
s propel the feces out of the rectum. The internal and external sphincter
Sphincter

A sphincter is a structure, usually a circular muscle, that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning....
 allow the feces to be passed by muscles pulling the anus up over the exiting feces.

Medical procedures

For the diagnosis of certain ailments, a rectal exam may be done.

Suppositories
Suppository

A suppository is a drug delivery system that is inserted either into the rectum , vagina or urethra where it dissolves.They are used to deliver both systemically-acting and locally-acting medications....
 may be inserted into the rectum as a route of administration
Route of administration

In pharmacology and toxicology, a route of administration is the path by which a medication, fluid, poison or other substance is brought into contact with the body....
 for medicine
Medicine

Medicine is the art and science of healing. It encompasses a range of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
.

The endoscopic
Endoscopy

Endoscopy means looking inside and typically refers to looking inside the body for medical reasons using an instrument called an endoscope....
 procedures colonoscopy
Colonoscopy

Colonoscopy is the endoscopy examination of the large Colon and the distal part of the ileum with a CCD camera or a fiber optic camera on a flexible tube passed through the anus....
 and sigmoidoscopy
Sigmoidoscopy

Sigmoidoscopy is the minimally invasive medicine examination of the large intestine from the rectum through the last part of the colon . There are two types of sigmoidoscopy, flexible sigmoidoscopy, which uses a flexible endoscopy, and rigid sigmoidoscopy, which uses a rigid device....
 are performed to diagnose diseases such as cancer
Cancer

Cancer is a class of diseases in which a group of cell display uncontrolled growth , invasion , and sometimes metastasis . These three malignant properties of cancers differentiate them from benign tumors, which are self-limited, do not invade or metastasize....
.

Temperature taking

Body temperature can also be taken in the rectum. Rectal temperature
Temperature

In physics, temperature is a physical property of a Physical system that underlies the common notions of hot and cold; something that feels hotter generally has the greater temperature....
 can be taken by inserting a mercury thermometer for 3 to 5 minutes, or a digital thermometer
Thermometer

The thermometer is a device that measures temperature or temperature gradient using a variety of different principles; it comes from the Greek language roots thermo, heat, and meter, to measure....
 until it "beeps", not more than 25 mm (1 inch) into the rectum via the anus
Anus

The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to expel feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest, such as coprolite ; food material after all the nutrients have b...
. Due to recent concerns related to mercury poisoning
Mercury poisoning

Mercury poisoning is a disease caused by exposure to mercury or its compounds. Mercury is a Heavy metal which occurs in several forms, all of which can produce toxic effects in high enough doses....
, the use of mercury thermometers is outlawed. Normal rectal temperature generally ranges from 36 to 38 °C (97.6 to 100.4 °F) and is about 0.5 °C (1 °F) above oral (mouth) temperature and about 1 °C (2 °F) above axillary
Axillary

Axillary is an anatomical term derived from axilla, the armpit. "Axillary" literally means "pertaining to the armpit".In vertebrate anatomy and medicine, it occurs in terms like:...
 (armpit) temperature.

Many pediatricians
Pediatrics

Differences between adult and pediatric medicinePediatrics differs from adult medicine in many respects. The obvious body size differences are paralleled by maturational changes....
 recommend that parents take infants and toddler
Toddler

Toddler is a common term for a young child who is learning to walk. The toddling stage is generally considered to be the stage of development between infant and childhood....
's temperature in the rectum for two reasons:
  • (1) Rectal temperature is the closest to core body temperature and in children that young, accuracy is critical.
  • (2) Younger children are unable to cooperate when having their temperature taken by mouth (oral) which is recommended for children, ages 6 and above and for adults.


In recent years, the introduction of ear (tympanic) thermometers and changing attitudes on privacy
Privacy

Privacy is the ability of an individual or group to seclude themselves or information about themselves and thereby reveal themselves selectively....
 and modesty
Modesty

Standards of modesty are aspects of the culture of a country or people, at a given point in time, and is a measure against which an individual in society may be judged....
 have led some parents and doctors to discontinue taking rectal temperatures.

Sexual stimulation

Due to the proximity of the anterior wall of the rectum to the vagina
Vagina

The vagina is a fibromuscular cylinder tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles....
 in females or to the prostate
Prostate

The prostate is a compound tubuloalveolar exocrine gland of the male mammalian reproductive system. Females do not have a prostate gland, although females do have tiny paraurethral Skene's glands connected to the distal third of the urethra in the prevaginal space that are homologous to the prostate....
 in males and the shared nerves thereof, rectal stimulation
Stimulation

Stimulation is the action of various agents on muscles, nerves, or a sensory end organ vyv, by which activity is evoked; especially, the nervous impulse produced by various agents on nerves, or a sensory end organ, by which the part connected with the nerve is thrown into a state of activity....
 or penetration can result in sexual arousal
Sexual arousal

Sexual arousal is the the arousal of sexual desires in preparation for sexual behavior....
. For further information on this aspect, see anal sex
Anal sex

Anal sex most often refers to the sex act involving insertion of the penis into the rectum. The term anal sex can also sometimes include other sexual acts involving the anus, including but not limited to Anal-oral sex and fingering #Anal fingering....
.

Additional images


See also

  • Gastrointestinal tract
    Gastrointestinal tract

    The digestive tract is the system of Organ s within multicellular animals that takes in food, digestion it to extract energy and nutrients, and expels the remaining waste....
  • Rectal prolapse
    Rectal prolapse

    Rectal prolapse normally describes a medical condition wherein the walls of the rectum protrude through the anus and hence become visible outside the body....
  • Pectinate line
    Pectinate line

    The pectinate line is a line which divides the upper 2/3rds and lower 1/3rd of the anal canal. Developmentally, this line represents the hindgut-proctodeum junction....
  • Murphy drip
    Murphy drip

    A Murphy drip is a Route_of_administration#Enteral apparatus to administer the medical procedure of proctoclysis, also known as rectoclysis. During the procedure, an end of the Murphy drip is inserted into the rectum and large quantities of liquid are infused into the rectum drop-by-drop....


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