What is the stomach?

The stomach is an organ that digests food. It produces enzymes and acids, this mix of enzymes and digestive juices breaks down food so it can pass to your small intestine.

Anatomy - Your stomach sits in your upper abdomen on the left side of your body. The top of your stomach connects to a valve called the esophageal sphincter. The bottom of your stomach connects to your small intestine.

Your stomach has five distinct sections:

  • The cardia is the top part of your stomach. It contains the cardiac sphincter, which prevents food from traveling back up your esophagus.

  • The fundus is a rounded section next to the cardia. It's below your diaphragm (the dome-shaped muscle that helps you breathe).

  • The body (corpus) is the largest section of your stomach. In the body, your stomach contracts and begins to mix food.

  • The antrum lies below the body. It holds food until your stomach is ready to send it to your small intestine.

  • The pylorus is the bottom part of your stomach. It includes the pyloric sphincter. This ring of tissue controls when and how your stomach contents move to your small intestine.

The Stomach

3D illustration of human digestive system highlighting the stomach, esophagus, and intestines.

What is the stomach’s structure?

Several layers of muscle and other tissues make up your stomach:

  • Mucosa is your stomach’s inner lining. When your stomach is empty, the mucosa has small ridges. When your stomach is full, the mucosa expands, and the ridges flatten.

  • Submucosa contains connective tissue, blood vessels, lymph vessels and nerve cells. It covers and protects the mucosa.

  • Muscularis externa is the primary muscle of your stomach. It has three layers that contract and relax to break down food.

  • Serosa is a layer of membrane that covers your stomach.

How can I keep my stomach healthy?

You can make lifestyle changes to keep your stomach healthy.

  • Drink alcohol only in moderation.

  • Drink plenty of water daily (your body weight divided by 2), depending on your lifestyle this will vary

  • Eat 25 to 35 grams of fiber daily, again depending on your gender and lifestyle this will vary

  • Exercise daily

  • Avoid processed foods

  • Learn how to mitigate stressors

  • Don’t smoke or use tobacco products.

What is the stomach’s function?

Your stomach’s purpose is to digest food and send it to your small intestine. It has three functions:

  • Temporarily store food.

  • Contract and relax to mix and break down food.

  • Produce enzymes and other specialized cells to digest food.

Diagram of the human stomach with labeled parts including the lower esophageal sphincter, esophagus, cardia, fundus, body, greater curvature, gastric folds (rugae), lesser curvature, pyloric sphincter, pyloric canal, pyloric antrum, pyloric opening, pylorus, and duodenum.

What conditions and disorders affect your stomach?

Gastrointestinal diseases may affect your stomach.

Common conditions that affect your stomach include:

  • Gastric Ulcers: Erosion of your stomach’s lining that can lead to pain and bleeding.

  • Gastritis: Stomach inflammation.

  • Gastroesophageal reflux disease or GERD: When stomach contents travel up to your esophagus, causing heartburn or coughing.

  • Gastroparesis: Nerve damage that affects your stomach’s muscle contractions.

  • Stomach Cancer: When cancerous cells grow uncontrollably in your stomach.

What are the parts of the spleen?

There are two parts of the spleen. They each do different jobs. The types of tissue in the spleen are:

  • White pulp: As part of the immune system, the white pulp produces white blood cells. These blood cells make antibodies. Antibodies fight infection.

  • Red pulp: The red pulp acts like a filter. It removes waste from the blood and gets rid of old or damaged blood cells. Red pulp also destroys bacteria and viruses.

Illustration of human spleen anatomy showing labeled sections including capsule, trabecula, vascular sinusoid, white pulp, red pulp, artery, and vein.

The Spleen

Illustration of a human torso with internal organs, highlighting the spleen in pink, and showing the heart, lungs, stomach, and intestines in blue.

What conditions and disorders affect this system?

Many disorders, conditions, injuries and diseases can cause problems in the spleen. These problems include:

Enlarged spleen: An enlarged spleen can cause pain, an uncomfortable feeling of fullness, even if you haven’t eaten much. Splenomegaly is a dangerous condition because the spleen can rupture or bleed. The spleen can become enlarged from:

  • Blood cancers, and cancer in other parts of the body that metastasize to the spleen.

  • Blood clots in the spleen or the liver.

  • Certain types of anemia, including hemolytic anemia.

  • Infections, including mono, syphilis, and endocarditis

  • Liver problems, including cirrhosis

What is the spleen?

Your spleen is a small organ that sits inside your left rib cage, just above your stomach. In adults, the spleen is about the size of an avocado. The spleen is part of your lymphatic system. It does several important jobs to keep your body healthy.

What does the spleen do?

Your spleen:

  • Stores blood.

  • Filters blood by removing cellular waste and getting rid of old or damaged blood cells.

  • Makes white blood cells and antibodies that help you fight infection.

  • Maintains the levels of fluid in your body.

  • Produces antibodies that protect you against infection.

Functional asplenia: This condition happens when your spleen doesn’t work as it should. It may overreact and destroy healthy red blood cells. Functional asplenia can result from:

  • An accident or trauma that damages the spleen.

  • Celiac disease

  • Sickle cell disease

Damaged or ruptured spleen: Your spleen can rupture from injuries and trauma. Car accidents and blows to the abdomen are common causes of spleen damage. This life-threatening injury can cause severe internal bleeding.

How can I keep my spleen healthy?

To keep your spleen, lymphatic system and immune system working properly, you should drink plenty of water, exercise daily and eat a healthy diet. Add manual lymphatic drainage and/or dry brushing to your daily self-care routine. By staying healthy, you’ll help your immune system protect you from infections and illness.

The Small Intestines

What is the small intestine?

Your small intestine is an important part of your digestive system. It connects your stomach to your large intestine. You rely on your small intestine to extract nutrients from the food your eat.

Your small intestine:

  • Breaks food down.

  • Absorbs nutrients and water.

  • Moves food along your gastrointestinal tract.

Conditions and Disorders

There are many illnesses that can affect your small intestines. Some of the more common ones include:

  • Celiac disease

  • Crohn’s disease

  • Enteritis

·        Irritable bowel syndrome (IBS)

  • Malabsorption

  • Meckel’s diverticulum

  • Peptic ulcer disease

  • Scleroderma

  • Small bowel obstruction

Illustration of human digestive system highlighting intestines

Anatomy

Your small intestine is inside your abdominal cavity. It’s a long coil of tissues and muscle that looks like a very long, thin, pink or red tube with many folds. Your large intestine surrounds your small intestine. Your small intestine has three parts. Each part is responsible for specific tasks that are essential to digesting food. Those parts are:

The duodenum - This is the first stop in your small intestine. It’s a short, roughly 10-inch-long, tube that receives food from your stomach. Your duodenum is where your small intestine makes the digestive juices and enzymes to break down food. Your gallbladder delivers bile, and your pancreas delivers digestive enzymes to your duodenum to help it break down food.

The jejunum - This is the second stop; this section of your small intestine is 8 feet long. It lays in coils inside the lower abdominal cavity. The jejunum is dark red due to its many blood vessels. It has muscles that churn food back and forth and mix it with digestive juices. Peristalsis, is an involuntary muscle movement in your digestive system, keeps food moving toward your ileum.

What are common symptoms of small intestine conditions and diseases?

Your small intestine absorbs nutrients and water from your food. Diseases and conditions that keep your small intestine from absorbing nutrients and water may cause the following symptoms:

  • Belly pain

  • Bloated stomach

  • Constipation

  • Diarrhea

  • Nausea and vomiting

  • Unexplained weight loss

What does the small intestine do?

Your small intestine turns semi-solid food into liquid so your body can absorb the nutrients you need. To do that, your small intestine:

  • Delivers digestive juices and enzymes to combine with bile which allows the digestive process to start.

  • It then breaks down and liquefies semi-solid food so your body can absorb and use the nutrients.

  • Next it absorbs nutrients and water through the villi in mucosa. The mucosa is the inner lining of your small intestine.

  • Finally, it turns what’s left behind into digestive waste that moves to your large intestine.

Diagram of human digestive system highlighting the duodenum, jejunum, ileum, large intestine, and rectum.

The ileum - This is the last stop and the longest section of your small intestine. It absorbs nutrients from digested food for your body to use, nutrients such as vitamins, minerals, carbohydrates, fats and protein. Your ileum moves the waste toward your large intestine. The ileum is where food spends the most time in the small intestine before moving to the large intestine.

What helps my small intestine function?

Taking care of your overall gut health is the best way to keep your small intestine healthy. Here are some suggestions:

  • Eat well: Plan meals that highlight fruits, vegetables and whole grains. Ask a dietitian about adding prebiotics and probiotics to your food plan.

  • Drink up: A steady flow of fluids — water and non-carbonated or caffeine-free drinks — helps your digestive system, including your small intestine, break down food.

  • Get your rest: Resting, specifically sleeping well, helps repair cells and support your immune system.

  • Manage stress: Stress can trigger conditions that affect your small intestine, like Crohn’s disease and irritable bowel syndrome.

  • Stay active: Regular activity improves blood flow to your intestines and vital organs and strengthens your muscles. It also boosts gut motility — the muscle contractions that move food through your GI tract.

The Large Intestine

What is the large intestine? Your large intestine is also part of your digestive system. It turns food waste into solid poop and manages the pooping process.

What does the large intestine do? Your large intestine receives the liquid food waste that’s left after your small intestine completes its part of the digestive process. It absorbs water and salts from the liquid waste and turns it into solid waste. Your large intestine uses layers of tissue and muscles to move poop out of your body.

Illustration of human digestive system showing liver, stomach, intestines.

The Colon

Your colon has five parts that work to process food waste and move waste to your rectum. Those parts are:

Cecum: This is the first part of your colon. It’s about 3 inches long. Your cecum receives digested food waste from your small intestine and moves it along to your ascending colon. Your appendix hangs off the end of your cecum.

Ascending colon: This is the second part of your colon. It’s about 8 inches long and 2.5 inches around. It runs from your cecum up to your transverse colon. It absorbs water and electrolytes in food waste. It then moves the waste up and sideways to your transverse colon.

Transverse colon: This is the longest part of your colon, measuring more than 18 inches. It runs from right to left at the top of your abdomen. It carries food waste to your descending colon.

Descending colon: Your descending colon is about 6 inches long. It sits on the left side of your body. It continues the process of turning food waste into poop.

Sigmoid colon: Your sigmoid colon, roughly 14 to 16 inches long, is the last part of your colon. It is final step in turning food waste into a solid mass.

Common Conditions and Disorders

A wide range of conditions and diseases can affect your large intestine, including ones specific to your colon, rectum and anus. Common issues include:

  • Anal fistula and fissures.

  • Constipation

  • Diarrhea

  • Fecal incontinence

  • Hemorrhoids

  • Inflammatory bowel disease

  • Irritable bowel syndrome (IBS)

  • Large bowel obstruction

  • Pelvic floor dysfunction

Anatomy

Where is the large intestine located? Your large intestine loops around your belly and your small intestine. It moves from a spot near your right hip up to your ribs. Then, it moves across your body and back down the left side of your belly. It’s 6 feet (1.8 meters) long and about 3 inches (about 8 centimeters) in diameter.

 What are the parts of the large intestine? Your large intestine has three parts: the colon, rectum and anus. Each part does specific things to keep food waste moving through your large intestine.

The Rectum

Your rectum is roughly 5 to 6 inches long. In this part of the digestive process, the parts of your large intestine reduce liquid waste by about one-third of its original size. When poop enters your rectum, it triggers your body’s urge to poop.

The Anus

This is the canal your poop goes through to leave your body. It’s about 2 inches long. Your anus has muscle sphincters that manage how poop leaves your body. A sphincter is like a fist that opens and closes. Your internal sphincter opens automatically to let poop through. The outer sphincter is the one you control to let poop out when you’re ready to go.

Diagram of the human intestines labeled with parts including small intestine, large intestine, cecum, appendix, ileum, colon, rectum, and anus.

Symptoms indicating potential problems

Many things may signal issues in your large intestine, but some common symptoms are:

  • Changes in your bowel habits, like diarrhea or constipation, trouble pooping or holding poop or changes in your poop, like bleeding, color or consistency changes.

  • Painful bloating and gas 

  • Significant fatigue.

How can I keep my large intestine healthy?

These general health guidelines will help you maintain a healthy gut:

  • Eat more fiber: Fiber triggers the muscle contractions that move food through your colon and help clear out residue there that could slow things down. Eating leafy greens and fruit is the best way to boost your fiber intake.

  • Eat better fats: Saturated fats, such as those found in red meat, are associated with higher rates of colon diseases. On the other hand, healthy fats — the omega-3s found especially in oily fish — promote friendly bacteria in the gut.

  • Drink more water: Your gut uses a lot of water — for cleansing, lubricating and absorbing nutrients — and most of us don’t drink enough of it.

  • Get your colonoscopy: Colon cancer is both common and preventable. Anyone with a colon can get it, and by the time you have symptoms, it might be too late to treat it. Regular screening is the best way to prevent it and treat it in time.

What is the gallbladder?

Your gallbladder is a small whose job is to store and release bile. Bile is the fluid your liver produces that helps digest fats in the food you eat.

Anatomy

Your gallbladder can be found in the upper right part of your abdomen belly. It sits just below your liver.

The Gallbladder

Human digestive system illustration highlighting the gallbladder in red.

Common issues that affect the gallbladder

Several conditions can cause problems in your gallbladder. Gallbladder diseases include:

  • Gallstones: Gallstones are similar to pebbles made of bile material that develop in the gallbladder or bile ducts. They can be as small as grains of sand to as large as golf balls. They’re usually harmless but can cause pain, nausea or inflammation.

  • Cholecystitis: Cholecystitis is inflammation of your gallbladder. It can occur when a gallstone blocks bile from exiting your gallbladder. Cholecystitis causes fever and pain and usually requires surgery.

  • Gallstone pancreatitis: Gallstone pancreatitis is inflammation of your pancreas. It occurs when a gallstone travels down the common bile duct and blocks the pancreatic duct at a common point just before draining into the small intestine.

What is the function of the gallbladder?

Your gallbladder is yet part of your digestive system. Its main function is to store bile. Bile is a mixture of mainly cholesterol, bilirubin and bile salts, this mixture is used to break down fats as the pass through the digestive system. Your gallbladder is connected to other parts of your digestive system through a series of bile ducts called the biliary tract. This tract leads from the liver to the small intestine.

What does the gallbladder do?

Your gallbladder is full of bile before you even start eating. So when you start eating, your gallbladder receives signals to contract squeezing the stored bile through the biliary tract. The bile finds its way to the common bile duct. As the bile passes through the common bile duct into the duodenum, it mixes with food waiting to be digested. After you eat, your gallbladder is empty and resembles a deflated balloon, waiting to be filled up again.

What are the signs or symptoms of gallbladder problems?

The symptoms of gallbladder problems vary. Some people don’t feel gallstones or even know they have them. But if gallstones block the bile from exiting, they can affect your gallbladder or pancreas. You may experience the following symptoms:

  • Upper right abdominal pain.

  • Upper mid abdominal pain.

  • Upper right abdominal pain radiating to the right shoulder or back.

  • Light-brown pee or light-colored poop.

The Pancreas

What is a pancreas? The pancreas is a large gland in the back of your abdomen. It’s part of your digestive system AND your endocrine system. It makes:

  • Enzymes to help with digestion -Exocrine

  • Hormones to control the amount of sugar in your bloodstream – endocrine

What does the pancreas do? Your pancreas helps with digestion and releases hormones that regulate your blood sugar. It also has a hand in supporting other organs like your heart, liver and kidneys.

Aids in digestion - Your pancreas makes about 1 to 4 liters of enzyme-rich juice each day to help you digest the foods you eat. The exact amount varies depending on how much food you eat.

After you eat, several organs actually work together to help you break it down. Here’s how the process when food enters your stomach:

1.    Your pancreas releases juice into small ducts that flow into your main pancreatic duct.

2.    Your main pancreatic duct connects with your bile duct. This duct transports bile from your liver to your gallbladder.

3.    From your gallbladder, the bile travels to part of your small intestine called the duodenum.

4.    Both the bile and the pancreatic juice enter your duodenum to break down food.

Produces hormones - Your pancreas makes hormones, such as insulin and glucagon, that help control the levels of sugar in your bloodstream. When your blood sugar is too high, your pancreas makes insulin lower it. When your blood sugar is too low, your pancreas makes glucagon increase it.

Your body needs balanced blood sugar to run properly (this is key for proper hormone function) and to keep organs like your heart, liver, kidneys and brain working well.

Illustration of human anatomy highlighting internal organs, including heart, lungs, stomach, pancreas, and intestines.

Anatomy

Where is the pancreas located? Your pancreas sits behind your stomach and in front of your spine. Your gallbladder, liver and spleen surround your pancreas. The head of your pancreas is on the right side of your body. It’s tucked beside the curve of your duodenum. The tail of your pancreas extends over to the left side of your body, near your spleen.

 Parts of the pancreas include the:

  • Head: The wider part of your pancreas that sits in the curve of your duodenum.

  • Neck: The short part of your pancreas extending from the head.

  • Body: The middle part of your pancreas between the head and neck, which extends upward.

  • Tail: The thinnest part of your pancreas, located near your spleen.

Conditions and Disorders

The following disorders can affect the pancreas:

  • Type 1 diabetes: Type 1 diabetes occurs when your pancreas doesn’t produce insulin.

  • Type 2 diabetes: Type 2 diabetes occurs when your body makes insulin but doesn’t use it correctly.

  • Hyperglycemia: Hyperglycemia happens when your body produces too much glucagon. This results in high blood sugar levels.

  • Hypoglycemia: Hypoglycemia occurs when your body produces too much insulin. It causes low blood sugar levels.

  • Pancreatitis: Pancreatitis happens when enzymes start to work in the pancreas before they reach the duodenum.

  • Pancreatic cancer: Cancerous cells in the pancreas cause pancreatic cancer.

How can I keep my pancreas healthy?

You can help reduce your risk of pancreatic conditions by:

  • Maintaining a weight that’s healthy for you. Regular exercise and reducing excess weight can help prevent Type 2 diabetes and gallstones that can cause pancreatitis.

  • Eating foods that are low in fat. High-fat foods can lead to gallstones, which can cause pancreatitis. Having obesity (a body mass index, or BMI, greater than 30) is also a risk factor for pancreatic cancer.

  • Watching your alcohol intake. Drinking alcohol can increase your risk of pancreatitis and pancreatic cancer.

  • Quitting smoking. Using tobacco, along with cigar smoking and smokeless tobacco products, can raise your risk of pancreatic cancer and chronic pancreatitis.

  • Getting regular checkups. Seeing your healthcare provider for regular exams can help find early signs of conditions like pancreatic cancer and pancreatitis.

Diagram of the human pancreas showing the head, body, and tail; bile duct; pancreatic duct; gallbladder; and duodenum.

Common symptoms of pancreatic conditions: Symptoms of pancreas problems may include:

  • Abdominal pain

  • Back pain

  • Blurred vision

  • Dark urine or light-colored, greasy stools

Illustration showing labeled human internal organs such as brain, heart, lungs, stomach, liver, kidneys, diaphragm, gallbladder, spleen, intestine, and male and female reproductive systems.

The Skin

What is the skin?

The skin is the body’s largest organ. Your skin protects your body from germs and regulates body temperature. Nerves in the skin help you feel sensations like hot and cold. Your skin, along with your hair, nails, oil glands and sweat glands, is part of the integumentary system.

Anatomy

What are the layers of the skin? Three layers of tissue make up the skin:

  • Epidermis, the top layer.

  • Dermis, the middle layer.

  • Hypodermis, the bottom or fatty layer.

Epidermis - Your epidermis is the top layer of the skin that you can see and touch. Keratin along with other proteins, sticks together to form this layer. The epidermis:

  • Acts as a protective barrier: The epidermis keeps bacteria and germs from entering your body and bloodstream and causing infections. It also protects against the elements.

  • Makes new skin: The epidermis continually makes new skin cells. These new cells replace the roughly 40,000 old skin cells that your body sheds every day. You have new skin every 30 days.

  • Protects your body: Langerhans cells in the epidermis are part of the body’s immune system. They help fight off germs and infections.

  • Provides skin color: The epidermis contains melanin, the pigment that gives skin its color. The amount of melanin you have determines the color of your skin, hair and eyes.

Conditions and Disorders - As the body’s external protection system, your skin is at risk for various problems. These include:

  • Allergies like contact dermatitis and poison ivy rashes

  • Blisters

  • Bug bites, such as spider bites, tick bites and mosquito bites

  • Skin cancer/melanoma

  • Skin infections like cellulitis

  • Skin rashes and dry skin

  • Skin disorders like acne, eczema, psoriasis and vitiligo

  • Skin lesions, such as moles, freckles and skin tags

  • Wounds, burns and scars

Dermis - The dermis makes up 90% of skin’s thickness. This middle layer of skin:

  • Has collagen and elastin: Collagen is a protein that makes skin cells strong and resilient. Elastin, another protein, keeps skin flexible. It also helps stretched skin regain its shape.

  • Grows hair: The roots of hair follicles attach to the dermis.

  • Keeps you in touch: Nerves in the dermis tell you when something is too hot to touch, itchy or super soft. These nerve receptors also help you feel pain.

  • Makes oil: Oil glands in the dermis help keep the skin soft and smooth. Oil also prevents your skin from absorbing too much water when you swim or get caught in a rainstorm.

  • Produces sweat: Sweat glands in the dermis release sweat through skin pores. Sweat helps regulate your body temperature.

  • Supplies blood: Blood vessels in the dermis provide nutrients to the epidermis, keeping the skin layers healthy.

Hypodermis - The bottom layer of skin, or hypodermis, is the fatty layer. The hypodermis:

  • Cushions muscles and bones: Fat in the hypodermis protects muscles and bones from injuries when you fall or are in an accident.

  • Has connective tissue: This tissue connects layers of skin to muscles and bones.

  • Helps the nerves and blood vessels: Nerves and blood vessels in the dermis get larger in the hypodermis. These nerves and blood vessels branch out to connect the hypodermis to the rest of the body.

  • Regulates body temperature: Fat in the hypodermis keeps you from getting too cold or hot.

Diagram of human skin layers, showing the outer layer (epidermis with stratum corneum), middle layer (dermis with elastin, collagen, and hyaluronic acid), and inner layer (hypodermis with fat cells and muscles)."}

How can you protect your skin? - You lose collagen and elastin as you age. This causes the skin’s middle layer to get thinner. As a result, the skin may sag and develop wrinkles. While you can’t stop the aging process, these actions can help maintain healthier skin:

  • Apply sunscreen every day. Choose a sunscreen with a broad-spectrum sun protection factor of at least 30.

  • Limit UV exposure. While you’re exposed to UV rays you should find shade or go inside when you start feeling too hot or your skin burning

  • Find healthy ways to manage stress. Stress can make certain skin conditions worse.

  • Perform regular skin and mole checks to look for changes that may be signs of skin cancer.

  • Quit smoking and using tobacco products. Nicotine and other chemicals in cigarettes and electronic cigarettes age skin faster.

  • Use gentle cleansers to wash your face in the morning and at night.

  • Shower regularly and apply moisturizing lotion to prevent dry skin.