Many of the internal organs of the human body
The digestive tract, with the esophagus marked in red
The liver and gallbladder of a sheep
The esophagus is constricted in three places.
Relationship of major animal lineages with indication of how long ago these animals shared a common ancestor. On the left, important organs are shown, which allows us to determine how long ago these may have evolved.
A mass seen during an endoscopy and an ultrasound of the mass conducted during the endoscopy session.
The flower is the angiosperm's reproductive organ. This Hibiscus flower is hermaphroditic, and it contains stamen and pistils.
Strobilus of Equisetum telmateia
Human viscera

The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the stomach.

- Esophagus

Digestive system: digestion and processing food with salivary glands, esophagus, stomach, liver, gallbladder, pancreas, intestines, colon, rectum and anus.

- Organ (biology)
Many of the internal organs of the human body

7 related topics

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Scheme of digestive tract, with stomach in red.

Stomach

Scheme of digestive tract, with stomach in red.
1. Body of stomach 2. Fundus 3. Anterior wall 4. Greater curvature 5. Lesser curvature 6. Cardia 9. Pyloric sphincter 10. Pyloric antrum 11. Pyloric canal 12. Angular incisure 13. Gastric canal 14. Rugae
Schematic image of the blood supply to the human stomach: left and right gastric artery, left and right gastroepiploic artery and short gastric artery.
The gastrointestinal wall of the human stomach.
Histology of normal fundic mucosa. Fundic glands are simple, branched tubular glands that extend from the bottom of the gastric pits to the muscularis mucosae; the more distinctive cells are parietal cells. H&E stain.
Histology of normal antral mucosa. Antral mucosa is formed by branched coiled tubular glands lined by secretory cells similar in appearance to the surface mucus cells. H&E stain.
An endoscopy of a normal stomach of a healthy 65-year-old woman.
Endoscopic image of a fundic gland polyp.
Greater omentum and stomach of humans
A more realistic image, showing the celiac artery and its branches in humans; the liver has been raised, and the lesser omentum and anterior layer of the greater omentum removed.
An autopsy of a human stomach, showing the many folds ({{wt|en|rugae}}) of the stomach. 2012 Instituto Nacional de Cardiología
Human stomach
High-quality image of the stomach

The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates.

In humans and many other animals, the stomach is located between the oesophagus and the small intestine.

Anatomy of the larynx, anterolateral view

Larynx

Anatomy of the larynx, anterolateral view
The basic parts of the human larynx.
Vocal cords abducted and adducted
Extrinsic laryngeal muscles
Image of endoscopy
Endoscopic image of an inflamed human larynx
Larynx. Deep dissection. Anterior view.
Larynx. Deep dissection. Posterior view.

The larynx, commonly called the voice box, is an organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration.

It is situated just below where the tract of the pharynx splits into the trachea and the esophagus.

Diagram of stomach, intestines and rectum in the average human

Gastrointestinal tract

Tract or passageway of the digestive system that leads from the mouth to the anus.

Tract or passageway of the digestive system that leads from the mouth to the anus.

Diagram of stomach, intestines and rectum in the average human
Illustration of the small intestine

The GI tract contains all the major organs of the digestive system, in humans and other animals, including the esophagus, stomach, and intestines.

Smooth muscle

Involuntary non-striated muscle, so-called because it has no sarcomeres and therefore no striations .

Involuntary non-striated muscle, so-called because it has no sarcomeres and therefore no striations .

Smooth muscle tissue, highlighting the inner circular layer (nuclei then rest of cells in pink), outer longitudinal layer (nuclei then rest of cells), then the serous membrane facing the lumen of the peritoneal cavity
The dense bodies and intermediate filaments are networked through the sarcoplasm, which cause the muscle fiber to contract.
A series of axon-like swellings, called varicosities from autonomic neurons, loosely form motor units through the smooth muscle.
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Smooth muscle is found in the walls of hollow organs, including the stomach, intestines, bladder and uterus; in the walls of passageways, such as blood, and lymph vessels, and in the tracts of the respiratory, urinary, and reproductive systems.

They can occur in any organ, but the usually occur in the uterus, small bowel, and esophagus.

Types of epithelium

Epithelium

One of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue.

One of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue.

Types of epithelium
Summary showing different epithelial cells/tissues and their characteristics.
Forms of secretion in glandular tissue
Different characteristics of glands of the body
Epithelial cell infected with ''Chlamydia pneumoniae
Squamous epithelium 100x
Human cheek cells (Nonkeratinized stratified squamous epithelium) 500x
Histology of female urethra showing transitional epithelium
Histology of sweat gland showing stratified cuboidal epithelium

Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs.

Tissues that line the inside of the mouth, the esophagus, the vagina, and part of the rectum are composed of nonkeratinized stratified squamous epithelium.

Heart

Human heart during an autopsy
Computer-generated animation of a beating human heart
The human heart is in the middle of the thorax, with its apex pointing to the left.
Heart being dissected showing right and left ventricles, from above
Frontal section showing papillary muscles attached to the tricuspid valve on the right and to the mitral valve on the left via chordae tendineae.
Layers of the heart wall, including visceral and parietal pericardium
The swirling pattern of myocardium helps the heart pump effectively
Arterial supply to the heart (red), with other areas labelled (blue).
Autonomic innervation of the heart
Development of the human heart during the first eight weeks (top) and the formation of the heart chambers (bottom). In this figure, the blue and red colors represent blood inflow and outflow (not venous and arterial blood). Initially, all venous blood flows from the tail/atria to the ventricles/head, a very different pattern from that of an adult.
Blood flow through the valves
The cardiac cycle as correlated to the ECG
The x-axis reflects time with a recording of the heart sounds. The y-axis represents pressure.
Transmission of a cardiac action potential through the heart's conduction system
Conduction system of the heart
The prepotential is due to a slow influx of sodium ions until the threshold is reached followed by a rapid depolarization and repolarization. The prepotential accounts for the membrane reaching threshold and initiates the spontaneous depolarization and contraction of the cell; there is no resting potential.
3D echocardiogram showing the mitral valve (right), tricuspid and mitral valves (top left) and aortic valve (top right).
The closure of the heart valves causes the heart sounds.
Cardiac cycle shown against ECG
Heart and its blood vessels, by Leonardo da Vinci, 15th century
Animated heart
Elize Ryd making a heart sign at a concert in 2018
The tube-like heart (green) of the mosquito Anopheles gambiae extends horizontally across the body, interlinked with the diamond-shaped wing muscles (also green) and surrounded by pericardial cells (red). Blue depicts cell nuclei.
Basic arthropod body structure – heart shown in red
The human heart viewed from the front
The human heart viewed from behind
The coronary circulation
The human heart viewed from the front and from behind
Frontal section of the human heart
An anatomical specimen of the heart
Heart illustration with circulatory system
Animated Heart 3d Model Rendered in Computer

The heart is a muscular organ in most animals that pumps blood through the blood vessels of the circulatory system.

Echocardiography can be conducted by a probe on the chest (transthoracic), or by a probe in the esophagus (transesophageal).

Female (left) and male (right) adult human bodies photographed in ventral (above) and dorsal (below) perspectives. Naturally-occurring pubic, body, and facial hair has been deliberately removed to show anatomy

Human body

Structure of a human being.

Structure of a human being.

Female (left) and male (right) adult human bodies photographed in ventral (above) and dorsal (below) perspectives. Naturally-occurring pubic, body, and facial hair has been deliberately removed to show anatomy
Diagram of the human heart
Digestive system
Skin
Nervous system
Internal gross anatomy of the male reproductive system
External female reproductive system with mons pubis highlighted
Internal gross anatomy of the female reproductive system
Female urinary system
Cavities of human body
Baby being carried
Anatomical study by Leonardo da Vinci
Figure drawing by Lovis Corinth (before 1925)
Two facing pages of text with woodcuts of naked male and female figures, in the Epitome by Andreas Vesalius, 1543

At maturity, there are roughly 30 –37 trillion cells in the body, an estimate arrived at by totaling the cell numbers of all the organs of the body and cell types.

The digestive system consists of the mouth including the tongue and teeth, esophagus, stomach, (gastrointestinal tract, small and large intestines, and rectum), as well as the liver, pancreas, gallbladder, and salivary glands.