Pig (and human) Structures!

Nictitating Membrane

A transparent third eyelid that moves laterally across the eye to moisten it. It is not present fully in humans.

Incisors

The eight frontmost teeth (4 on top and 4 on bottom) in the mouth. They help cut and separate food.

Molars

The twelve most posterior teeth in the mouth. They are used for chewing and grinding.

Hard Palate

The anterior segment of the roof of the mouth. It divides the oral cavity from the nasal passages.

Soft Palate

Posterior of the roof of the mouth. Contains muscles that close the nasal passages and airways when swallowing. It is directly connected to the uvula.

Lymph Nodes

Many small bean-shaped organs throughout the body. They help filter out diseases and bacteria while facilitating immune responses. Major groups of them are located in the axillary, cervical, inguinal, and sternal areas.

Pharynx

It is the throat, acting as a passageway for both food and air. Reaches from the base of the nasal cavity down to the esophagus.

Larynx

Sits inferior to the throat, and contains the voice box. Acts as part of the passageway for air into the lungs and forms the Adam’s apple.

Epiglottis

A small piece of elastic cartilage that covers the entry to the windpipe during swallowing and eating food. It opens to let you breathe.

Superficial Fascia

Located directly beneath the skin, it provides support and cushioning to many body structures as part of the integumentary system.

Deep Fascia

This structure is slightly deeper than the skin, while similarly covering the entire body. It works closely with muscles and provides direct support to keep blood vessels, bones, and muscles where they need to be.

Muscles

The indispensable soft tissue organs that contract to create almost all movement in the body.

Tendons

Tough cords made of collagen that connect muscles directly to the bone to force different body parts to move.

Ligaments

They connect bones directly to each other and stabilize joints.

Trachea

The windpipe, carries air between the voice box and the lungs. It is made up of cartilage rings connected by ligaments.

Bronchi

Two passageways that split from the bottom of the windpipe and lead air into and out of the lungs.

Lungs

Two large organs in the chest that pump air into the blood and release carbon dioxide as a waste product of breathing.

Diaphragm

This is the muscle responsible for inflating and deflating the lungs, since they cannot operate by themselves. It is located directly below the lungs and it contracts downward to create a vacuum that forces air in.

Ribs

Twelve pairs of bones that protect the thoracic cavity and the organs inside. It also includes joints so that it can expand with the lungs.

Sternum

Bone that anchors the front of the ribs and connects to the clavicles.

Heart

This muscular organ is the center of the circulatory system, pumping blood throughout the body in regular intervals.

Thyroid Gland

A butterfly-shaped endocrine organ that lies below the voice box and against the windpipe. It regulates the metabolic rate to maintain homeostasis.

Carotid Artery

Two major blood vessels that provide oxygenated blood to the head and brain. They extend upward from the heart to the corners of the jaw.

Vagus Nerves

The main pathways of the parasympathetic nervous system. They allow communication between the brain stem, heart, and digestive system, extending from the brain down to the small intestine. It helps control a lot of involuntary body movements.

Thymus Gland

A key player in the lymphatic AND endocrine systems, nestled between the lungs and just above the heart. In early life, it produces and regulates T-cells that help your body combat disease.

Pericardium

This is a fluid filled sac surrounding your heart. It protects and secures the heart so that it stays in the correct spot without much friction with the surrounding tissue.

Right Ventricle

This is the lower right section of the heart. Receives oxygen-poor blood and pumps it to the lungs to be oxygenated.

Left Ventricle

This is the strongest part of the heart, located in the lower left section. It sends oxygenated blood to nearly every part of the body.

Right Atrium

The upper right part of the heart. It is responsible for collecting oxygen poor blood from veins and giving it to the pump that takes it to the lungs to be oxygenated.

Left Atrium

Upper left part of the heart that collects oxygenated blood and sends it to the heart’s major pump to be dispersed into the body.

Superior Vena Cava

A large, short vein extending up from the heart that transports deoxygenated blood from the body’s upper regions back to the heart (right atrium).

Inferior Vena Cava

The largest vein in the body, extending beneath the heart. It transports deoxygenated blood from the body’s lower half back to the heart (right atrium).

Aortic Arch

Directs oxygenated blood from the heart’s left ventricle to many different pathways throughout the body. It is a curved structure right above the heart.

Thoracic Aorta

This constitutes the entire section of the Aortic artery above the diaphragm. It ascends first from the heart before curving downward between the lungs, carrying oxygenated blood.

Abdominal Aorta

This is a continuation of the aortic artery below the diaphragm that breaks down further into smaller arteries, carrying oxygenated blood throughout the lower body and major organs.

Peritoneum

A large membrane in the abdominal cavity that surrounds many vital organs like the liver and stomach, dividing them from others like the kidneys and pancreas, which sit behind it. This membrane helps keep structure and reduce friction between tissues.

Liver

This is the largest internal organ in the body. It performs many functions, including, but not limited to: chemical blood filtration, bile production, energy storage, and cholesterol production. It is located immediately inferior to the diaphragm.

Gallbladder

Small pear shaped organ directly inferior to the liver’s right side. It stores and releases bile that was created by the liver.

Common Bile Duct

This is a small tube that transports bile from the gallbladder directly to the small intestine to help break down and digest fats.

Esophagus

A muscular tube extending from the throat down to the stomach that carries food and water to be digested.

Stomach

A hollow muscular organ that stores and breaks down foods using strong enzymes and acids. It is located posterior to the liver and directly connects the esophagus to the small intestine.

Fundus

The superior curved part of the stomach that stores gas released during digestion.

Body

Largest section of the stomach. It is located in the center, and begins to contract, mixing and churning food.

Antrum

Section of the stomach that lies below the body, it holds food before it is sent through to the small intestine.

Pyloric Valve

Sphincter at the bottom of the stomach that opens and closes to control when food is passed to the small intestine.

Cardia

The opening to the stomach that food and water pass through to enter. It helps keep stomach acid out of the esophagus, and contains a sphincter to keep food from re-entering the esophagus. (Hint: we call it heartburn when stomach acid makes it past the sphincter and damages the esophagus)

Rugae

The name for folds in the walls of an organ that allow flexibility and expansion. They can be found in the walls of the stomach, the hard palate, and the gallbladder.

Small Intestine

This is the longest section of the gastrointestinal tract, located inferior to the liver and stomach in the abdominal cavity. It turns semisolid foods and water into nutrients that are absorbed through the inner lining, and waste, which is sent through to the next section of the gastrointestinal tract.

Duodenum

This structure is the beginning of the small intestine, connecting it with the stomach. It takes in bile from the gallbladder and enzymes from the pancreas. It produces digestive juices that help it break down food further.

Jejunum

This structure is the second section of the small intestine. It further churns food and moves it through the gastrointestinal tract using muscles in its walls that are controlled involuntarily (peristalsis).

Ileum

The final and lowest stage of the small intestine. This section absorbs nutrients like vitamins, minerals, carbohydrates, fat, protein, and water while moving waste toward the colon. It also contains a valve at the end to prevent backwash from the large intestine.

Spleen

This structure regulates red blood cells and houses white blood cells to keep the immune system healthy. It also stores excess blood to add more into circulation if the supply is low. It is located behind the stomach and just below the rib cage on the left side.

Pancreas

This structure is located in the curve of the duodenum, and has two purposes. As part of the endocrine system, it acts as a gland that regulates blood sugar levels. As a part of the digestive system, it releases enzymes directly into the duodenum to help break down food.

Mesentery

This structure is a double-folded part of the peritoneum that attaches the intestines to the posterior of the abdominal cavity. It carries blood and other important things to the intestines and other organs like the pancreas, spleen, and liver.

Cecum

This structure is the entry into the colon. It absorbs water and salt that remain after digestion in the small intestine. It also has muscular walls that continue to mix and churn remaining food.

Appendix

This structure is a small tube attached to the inferior of the cecum. It was long thought to be vestigial, but it has recently been shown to contain helpful immune cells and gut bacteria.

Large Intestine

This structure is a wide tube wraps around the small intestine. It turns excess food, now devoid of nutrients, into waste and absorbs excess water. It connects the small intestine to the rectum.

Ascending Colon

This is the second part of the colon, transporting waste up from the cecum while removing electrolytes and water.

Transverse Colon

This is the third part of the large intestine, and it travels from right to left, directly superior to the small intestine. It transports stool while absorbing water and salt.

Descending Colon

The fourth part of the large intestine, this structure starts in the left hypochondriac area and descends down until it connects to the rectum. It continues the same job of removing salt and water from the food and transporting the stool.

Kidneys

These are two retroperitoneal bean-shaped organs on either side the spine just below the ribs. They physically filter the blood and transport the waste out in the form of urine. They also control the blood pH and make glucose if the blood doesn’t have enough.

Rectum

Connects the colon and the anus. It absorbs excess water and contain nerves that trigger the urge to defecate when it holds solid waste.

Urinary Bladder

This structure is a spherical, hollow organ that sits behind the pubic bone in the pelvic cavity. It holds urine transported from the kidneys and contains nerves that tell the brain to contract the bladder and urinate.

Ureters

These are two small muscular tubes that transport urine from the kidneys to the bladder.

Penis

Male external sex organ located below the pubic bone on the anterior side. It is used for reproduction and sexual pleasure, and as the body’s exit for urine.

Scrotum

This is a sac of thick skin that protects and maintains the testes. It hangs outside the body to maintain a lower temperature and can retract closer to the body to warm up. This helps maintain the optimal temperature for semen production.

Testes

These are male sex organs located in the scrotum, below the penis. They are responsible for producing sperm used in reproduction, and testosterone used to induce sex drive and puberty.

Epididymis

This is a small, tightly coiled male sex organ attached to the posterior of each testicle. It serves as a reservoir for sperm and an environment for sperm to mature.

Urethra

In females, this structure attaches the bladder to the exterior of the pelvic cavity anterior to the vagina, allowing urination. In males, it attaches to the penis and also carries semen during ejaculation.

Urogenital Opening

This structure is the shared exit for urine and reproductive fluid, meaning in humans, it is only present for males at the end of the urethra. Human females have developed two separate openings for the different fluids (urethral and vaginal openings), but this opening is still present in many animals, like pigs. It is ventral to the anal canal at the bottom of the pelvic cavity.

Anus

This is the external opening at the very end of the digestive tract where poop exits the body. It is posterior to the male and female sex organs at the bottom of the pelvic cavity.

Ovaries

These are important glands in females that facilitate pregnancy and the menstrual cycle. They do not produce eggs after birth, but they store them for a person’s lifetime. One egg is released every month in time with the menstrual cycle for fertility. They also produce estrogen, which is important for sexual and reproductive health.

Uterine Horns

Structures in the uterus that extend from the top corners to connect to the fallopian tubes. They resemble horns, but these structures are much more pronounced in many non-human mammals (like pigs).

Uterus

This is an important organ in the lower abdomen in the female reproductive system where a fertilized egg will grow to become a fetus. During labor, the organ’s muscular walls will contract to widen the cervix and push the baby out of the vagina.

Vagina

This is a female sex organ located at the bottom of the pelvic area, posterior to the urethra and anterior to the anus. It is used for reproduction and sexual pleasure, as well as the exit for newborns during childbirth.