Digestive System Overview

Connects large intestine to the posterior abdominal wall.

Tissue lining the abdomen, can get inflamed or infected.

The mouth; the first part of the digestive tract.

The process of swallowing.

Separates the nasal and oral cavities.

Produce saliva to lubricate food and start digestion.

Tube that connects the throat to the stomach.

Where the esophagus passes through the diaphragm.

Crown (covered by enamel), dentin, pulp cavity (blood vessels and nerves), cementum (root anchor).

Inflammation and decay of the gums and tissues holding teeth in place, often a bacterial infection.

The process of chemically breaking down food using enzymes.

The process of bringing nutrients into the body.

Physical breakdown of food (e.g., chewing).

Innermost layer of the digestive tract, secretes mucus and is lined with epithelial tissue for protection.

Connective tissue layer with blood vessels, lymph vessels, and nerves.

Layer with smooth muscle for peristalsis (moving food).

Outermost protective layer; serosa in most of the tract, except for pharynx, esophagus, rectum where it is called adventitia.

Undulating movements of smooth muscle that move food through the digestive tract.

Glands that aid in digestion (e.g., salivary glands, liver, pancreas).

The tube-like digestive tract, approximately 20ft long.

Substances produced by the liver that help emulsify fats in the small intestine, breaking them down into smaller droplets for easier digestion.

Waste products formed from the breakdown of red blood cells by the liver. These pigments are excreted in bile and give feces their characteristic brown color.

A mixture of digestive enzymes and bicarbonate ions, produced by the pancreas, that flows into the duodenum to neutralize stomach acid and break down food further.

The pancreas is located behind the stomach and the duodenum, in the retroperitoneal space.

The point where the pancreatic duct and common bile duct join together before emptying into the duodenum.

The small intestine is responsible for approximately 90% of the digestion and absorption of nutrients from food. It has three sections: the duodenum, jejunum, and ileum.

Villi are tiny finger-like projections lining the small intestine, increasing surface area for absorption. Lacteals are specialized lymphatic capillaries inside each villi, absorbing fats.

These are two types of muscle contractions in the small intestine. Segmentation churns and mixes food, while peristalsis propels food forward.

The release of digestive juices and enzymes from specialized cells in the digestive tract. These substances help break down food and aid in digestion.

The removal of waste products from the body that are not absorbed or used. This includes undigested food and other byproducts of metabolism.

The process of solidifying waste (indigested food) in the large intestine, forming feces to be eliminated from the body.

Your digestive system would be significantly affected. You wouldn't produce enough digestive enzymes needed to break down food, leading to maldigestion. This can lead to nutrient deficiencies, weight loss, and even damage to your intestines due to the lack of digestive enzymes.

You wouldn't be able to adequately digest fats. Bile, produced by the liver, helps break down fats into smaller molecules that can be absorbed by the small intestine. Without bile, fat digestion and absorption would be severely reduced.

The urinary system is responsible for filtering waste products from the blood, producing urine, and regulating blood pressure, pH, glucose, and ion levels.

The kidneys are located retroperitoneally, meaning they sit behind the peritoneum lining in the abdominal cavity.

The kidney is surrounded by three tissue layers: the fibrous capsule (maintains shape), the adipose capsule (protection), and the renal fascia (attachment to the abdominal wall).

The kidney has two main regions: the cortex (outer layer) and medulla (inner layer). The cortex contains the renal corpuscle, convoluted tubules, and the proximal ends of collecting ducts. The medulla contains the nephron loops and distal ends of collecting ducts.

Nephrons are the functional units of the kidney. They filter blood to form urine and transport it out of the kidney.

Urine flows from nephrons to collecting ducts, then to calyces, merging into the renal pelvis, and finally draining into the ureter.

The glomerulus is a specialized capillary network within the nephron responsible for filtering blood. It receives 25% of the blood flow directly from the renal arteries.

The abdominal aorta branches into renal arteries, which then branch into smaller arteries supplying different kidney sections. Ultimately, afferent arterioles deliver blood to the glomerulus for filtration.

The process where the renal corpuscle filters blood plasma, preventing blood cells from entering the nephron.

The process where useful substances are reabsorbed from the tubules back into the bloodstream. Water, ions, and nutrients are reabsorbed into capillaries.

The process where specific wastes are pumped into the urine. Metabolic wastes, toxins, and drugs are secreted.

A condition where there is a decrease or cessation of glomerular filtration. This leads to enlarged kidneys, edema, metabolic acidosis, urea accumulation in the blood, and calcium deficiency.

A medical procedure that filters blood to remove waste and excess fluid when the kidneys are no longer functioning properly.

A type of dialysis that uses the peritoneal membrane to filter blood.

Two tubes that sit retroperitoneally and carry urine from the kidneys to the urinary bladder. They enter the bladder from the bottom and have no valves.

A muscular sac located anterior to the rectum that stores urine. It has three layers: mucosa (transitional epithelium), submucosa, and muscularis (detrusor muscle).

The ovaries are the female gonads, responsible for producing female gametes (eggs) and secreting hormones like estrogen, progesterone, and inhibin.

The uterine tubes, also known as fallopian tubes, connect the ovaries to the uterus. They provide a pathway for the sperm and oocyte to meet. Ciliated cells in the lining help move the oocyte towards the uterus.

The uterus has three layers: the perimetrium (outer), myometrium (middle), and endometrium (inner). The myometrium is a strong muscle layer responsible for contractions during labor. The endometrium is the lining that thickens and sheds during the menstrual cycle.

The corpus luteum is a temporary endocrine gland that forms after ovulation. It releases progesterone and estrogen to prepare the uterus for potential implantation of a fertilized egg.

Oocyte development involves four phases: oogonia (stem cells in the embryo), primary oocytes (begin meiosis I in the fetus), secondary oocytes (released during ovulation), and ovum (after fertilization).

The vagina is the birth canal and also acts as a receptacle for the penis during intercourse. It has folds called rugae that allow for expansion during childbirth.

Mammary glands are modified sweat glands primarily responsible for milk production during lactation. Under hormonal influence, they secrete milk to nourish a newborn baby.

The scrotum, which contains the testicles, has two layers: the dartos muscle (external) and the cremaster muscle (internal). These muscles regulate the temperature of the testicles for optimal sperm production.

Semen consists of sperm cells produced by the testes and fluids contributed by various glands: seminal vesicles (60%), prostate (25%), and bulbourethral glands (5%).

Sex refers to biological differences between males and females, including chromosomes, reproductive organs, and hormones. Gender refers to socially constructed roles, behaviors, expressions, and identities associated with being male or female.

Male and female are terms used to describe biological sex. Man and woman are terms used to describe gender identities and roles.

Meiosis is a specialized cell division process that produces gametes (sperm and egg cells) with half the number of chromosomes of a normal cell.

Meiosis results in the production of four gametes from a single starting cell.

The first stage of prenatal development, lasting from fertilization to the end of the second week, characterized by rapid cell division and implantation.

Ovulation releases a mature egg called a secondary oocyte, surrounded by the corona radiata (granulosa cells) and zona pellucida (protective layer).

Fertilization occurs when a sperm penetrates a secondary oocyte, fusing their nuclei and creating a zygote with 46 chromosomes.

After fertilization, the zygote undergoes rapid cell division (cleavage), forming a solid ball of cells called a morula.

The morula develops a fluid-filled cavity, becoming a blastocyst with an outer trophoblast (future placenta) and inner cell mass (future embryo).

The blastocyst embeds itself in the uterine wall, establishing the placenta and beginning the development of the embryo.

The three primary germ layers are ectoderm, mesoderm, and endoderm. They form during embryonic development and give rise to all the tissues and organs of the body.

The ectoderm forms the outer layer of the body, including the skin, hair, nails, and the nervous system. It also forms the lining of the mouth and anus.

The mesoderm forms muscles, bones, connective tissue, and the circulatory system. It also forms the lining of the body cavities.

The endoderm forms the lining of the digestive tract, the respiratory system, and the urinary system. It also forms the glands of these systems.

Neurulation is the process of forming the central nervous system (brain and spinal cord) from the ectoderm.

Neurulation occurs in four steps: 1. The ectoderm thickens to form the neural plate. 2. The neural plate folds inward to form the neural groove. 3. The raised sides of the neural groove (neural folds) grow upward. 4. The neural folds fuse to form the neural tube, which develops into the brain and spinal cord.

The amniotic sac surrounds the embryo and is filled with amniotic fluid, which cushions and protects the developing embryo.

The yolk sac is involved in the formation of the first blood cells and gets absorbed as the embryo develops.

Extraembryonic membranes are important structures that develop alongside the embryo and support its growth. These include the amnion, yolk sac, allantois, and chorion.

Fetal circulation involves unique adaptations to bypass the lungs. Oxygenated blood from the placenta is carried to the fetus through the umbilical vein. The ductus venosus shunts blood away from the liver and into the inferior vena cava. The ductus arteriosus allows blood to bypass the lungs and directly enter the aorta. The foramen ovale permits blood flow from the right atrium to the left atrium, bypassing the pulmonary circulation.

The three pairs of salivary glands are the parotid, sublingual, and submandibular glands. They secrete saliva, which lubricates food, breaks down carbohydrates, and fights bacteria.

A tooth has three main layers: enamel (outer, protective), dentin (middle, mineralized), and pulp (inner, containing blood vessels, nerves, and connective tissue).

The pharynx is a muscular tube that connects the mouth to the esophagus and the nasal cavity to the trachea. It plays a crucial role in swallowing and breathing, and is also involved in speech production.

The esophageal hiatus is an opening in the diaphragm through which the esophagus passes to connect to the stomach.

Deglutition, or swallowing, has three phases: the voluntary (tongue pushes food back), the pharyngeal (soft palate closes, bolus moves down), and the esophageal (peristalsis carries food to the stomach) phases.

The stomach has four main parts: the cardia (entrance), fundus (storage), body (main part), and pyloric region (exit).

Rugae are folds in the stomach lining, allowing it to expand and increase its surface area to hold more food.

The stomach lining has specialized cells: mucous cells (secrete mucus), parietal cells (produce HCl and intrinsic factor), chief cells (secrete pepsinogen), and enteroendocrine cells (secrete gastrin).

These are accessory organs of digestion. The liver produces bile to emulsify fats, the gallbladder stores bile, and the pancreas produces digestive enzymes and bicarbonate ions.

The muscularis layer of the stomach has three layers: oblique (inner), circular (middle), and longitudinal (outer). These layers work together to churn and mix food.

The small intestine has circular folds, villi, and microvilli, which all collectively increase the surface area for maximum nutrient absorption. This is crucial for efficient digestion and absorption of nutrients from the food we eat.

Celiac disease is an autoimmune disorder triggered by gluten. It damages the villi in the small intestine, turning them into scar tissue. This makes it difficult to digest food, leading to problems like bloating and chronic diarrhea.

The large intestine transforms chyme from a liquid to a solid state. Bacteria residing within it digest leftover food, creating vitamins K and B. Its four parts are the cecum, colon, rectum, and anal canal.

The appendix is a small pouch attached to the cecum. It houses some intestinal bacteria and can sometimes get clogged with chyme, leading to appendicitis.

The colon has two smooth muscle layers, but they do not surround the entire colon. This creates the 'bumps' on the large intestine called haustra.

The anal canal has two sphincters: the internal anal sphincter (smooth muscle) and the external anal sphincter (skeletal muscle). These work together to control defecation.

Diarrhea is the rapid passage of food through the intestines, resulting in loose, watery stools. It often occurs when food isn't properly digested or when gut bacteria are out of balance.

Constipation is the slow movement of food through the intestines, leading to infrequent, hard stools. It can be caused by lack of fiber in the diet, dehydration, or other factors.

Clostridium difficile, or C. diff, is a deadly infection caused by bacteria. It can lead to severe, bloody diarrhea for months and often arises after antibiotic use, as these kill off good bacteria, allowing harmful ones to take over.

A fecal transplant is a medical procedure where healthy bacteria from a donor's stool is transferred to a recipient's intestines. This helps restore the balance of gut bacteria and treat infections like C. diff.

Bile is produced by the liver and helps to emulsify fats in the small intestine. This means it breaks down large fat globules into smaller droplets, making it easier for digestive enzymes to work on them.

The gallbladder stores bile produced by the liver. When you eat fatty foods, the gallbladder releases bile into the small intestine through the cystic duct.

Gallstones are hard deposits that form in the gallbladder. They're usually made of cholesterol or bilirubin, a waste product from red blood cell breakdown.

The pancreas has two main roles: 1) It produces digestive enzymes to break down carbohydrates, proteins, and fats. 2) It secretes bicarbonate, which neutralizes stomach acid in the small intestine.

The hepatopancreatic ampulla is the opening where both the pancreatic duct and the common bile duct join together before entering the small intestine.

If bile flow is interrupted, the body can't properly digest fats. This can lead to problems absorbing fat-soluble vitamins (A, D, E, and K) and may cause digestive issues like diarrhea.

The small intestine is the main site for digestion and absorption of nutrients. It has three main sections: the duodenum, jejunum, and ileum.

The inside of the small intestine is covered in villi, which are tiny finger-like projections that increase the surface area for absorption. Each villi also contains a lymphatic capillary called a lacteal, which absorbs fats.

The small intestine has two main movements: 1) Segmentation, which churns and mixes food. 2) Peristalsis, which propels food forward.

The ileocecal sphincter is a valve that controls the movement of food from the small intestine into the large intestine. This ensures that food is properly digested and absorbed before moving on.

The urinary system filters waste products from the blood, produces urine, and regulates blood pressure, pH, glucose, and ion levels.

The kidneys are located retroperitoneally, meaning they sit behind the peritoneum lining in the abdominal cavity.

The kidney is surrounded by three tissue layers: the fibrous capsule (maintains shape), the adipose capsule (protection), and the renal fascia (attachment to the abdominal wall).

The kidney has two main regions: the cortex (outer layer) and medulla (inner layer). The cortex contains the renal corpuscle, convoluted tubules, and the proximal ends of collecting ducts. The medulla contains the nephron loops and distal ends of collecting ducts.

Nephrons are the functional units of the kidney. They filter blood to form urine and transport it out of the kidney.

Urine flows from nephrons to collecting ducts, then to calyces, merging into the renal pelvis, and finally draining into the ureter.

The glomerulus is a specialized capillary network within the nephron responsible for filtering blood. It receives 25% of the blood flow directly from the renal arteries.

Urine formation involves three main steps: glomerular filtration (filtering blood in the renal corpuscle), tubular reabsorption (taking back useful substances), and tubular secretion (removing unwanted substances).

Two tubes that sit retroperitoneally and carry urine from the kidneys to the urinary bladder. They enter the bladder from the bottom and have no valves.

A muscular sac located anterior to the rectum that stores urine. It has three layers: mucosa (transitional epithelium), submucosa, and muscularis (detrusor muscle).

The ureter's mucosa consists of two layers: transitional epithelium, which allows for stretching to accommodate varying urine volume, and lamina propria, which provides structural support.

The glomerulus acts as a filter in the nephron, separating blood plasma from larger molecules like proteins and blood cells. Only water, electrolytes, and small molecules pass through into Bowman's capsule.

The Juxtaglomerular apparatus monitors blood pressure and filtration rate within the nephron. Specialized cells, macula densa and juxtaglomerular cells, regulate blood flow and pressure through hormone release.

The nephron performs three vital functions: glomerular filtration (filtering blood plasma), tubular reabsorption (reclaiming useful substances), and tubular secretion (removing waste products).

Renal failure leads to a decline in glomerular filtration, resulting in enlarged kidneys, fluid retention (edema), metabolic acidosis, urea build-up in the blood, and calcium deficiency.

The ureter has three layers: the mucosa (transitional epithelium and lamina propria), the muscularis (smooth muscle for peristalsis), and the adventitia (outer connective tissue layer).

The urinary bladder has three layers: the mucosa (transitional epithelium), the submucosa (connective tissue), and the muscularis (detrusor muscle for bladder contraction).

The male urethra is about 8 inches long and passes through the prostate, while the female urethra is about 1.5 inches long and is shorter and separate from the reproductive system.

Micturition is the process of urination. Stretch receptors in the bladder send signals to the spinal cord when the bladder fills, triggering relaxation of the internal urethral sphincter, contraction of the detrusor muscle, and inhibition of the external urethral sphincter, leading to urine expulsion.

Aging leads to a decline in nephron function, reducing filtration and urine production. In men, the prostate may enlarge, potentially obstructing the urethra and making urination difficult.

The corpus luteum is a temporary endocrine gland that forms after ovulation. It releases progesterone and estrogen to prepare the uterus for potential implantation of a fertilized egg.

Neurulation occurs in four steps: 1. The ectoderm thickens to form the neural plate. 2. The neural plate folds inward to form the neural groove. 3. The raised sides of the neural groove (neural folds) grow upward. 4. The neural folds fuse to form the neural tube, developing into the brain and spinal cord.

Sex refers to biological characteristics like chromosomes, reproductive organs, and hormones. Gender is a social construct – roles, behaviors, and expressions based on being male or female.

Male and female are terms for sex. Man and woman are terms for gender.

Meiosis is a special cell division that makes gametes (sperm or egg cells) with half the chromosomes. It produces 4 cells from one.

The first stage of development from fertilization to 2 weeks, marked by rapid cell division and implantation.

A hollow ball of cells with an outer trophoblast (future placenta) and inner cell mass (future embryo).

Cells in the inner cell mass move and separate to form the 3 germ layers (ectoderm, mesoderm, endoderm). This marks the transition to the Embryonic stage.

The Ectoderm forms the outer layer of the body, including skin, hair, nails, and the nervous system.

The Mesoderm forms muscles, bones, connective tissue, and the circulatory system.

The Endoderm forms the linings of the digestive, respiratory, and urinary systems, plus their glands.

Neurulation is the process that creates the central nervous system (brain and spinal cord) from the Ectoderm.