ANATOMY 3

• Bulbourethral glands, also known as Cowper glands, produce alkaline fluid necessary for sperm viability.
• The prostate gland is a triple-lobed organ situated at the base of the bladder that produces an alkaline substance that protects sperm against the acid environment of the vagina.
• The penis is an organ of copulation composed of erectile tissue that encloses the urethra, the structure that expels urine and semen from the body.
• The production of male sex cells (sperm) and their transportation to sites of fertilization are vital functions of the penis.
• The scrotum is a sac of loose skin, fascia, and smooth muscle divided into two pouches by a septum that regulates the temperature of the testes.
• The testes are paired oval glands measuring 2 in x 1in that are surrounded by a dense white capsule and are divided into 200-300 compartments called lobules.
• Each seminiferous tubule is filled with sperm forming cells, Sertoli cells (supporting cells), and interstitial cells in between tubules that secrete testosterone.
• Sertoli cells extend from the basement membrane to the lumen, form the blood-testis barrier, support developing sperm cells, produce fluid, and control the release of sperm into the lumen.
• Sertoli cells secrete INHIBIN which slows sperm production.
• The muscularis mucosae throws the mucous membrane of the stomach and small intestine into many small folds, which increase the surface area for digestion and absorption.
• The mucosa is the inner lining of the GI tract and is involved in peristaltic reflexes.
• The lamina propria supports the epithelium and binds it to the muscularis mucosae.
• The lamina propria is areolar connective tissue containing many blood and lymphatic vessels, which are the routes by which nutrients absorbed into the GI tract reach the other tissues of the body.
• The epithelium functions in secretion and absorption and lines the stomach and intestines.
• Mucosa associated lymphatic tissue (MALT) is present all along the GI tract, especially in the tonsils, small intestine, appendix, and large intestine.
• The wall of the GI tract from the lower esophagus to the anal canal has the same basic, four-layered arrangement of tissues: mucosa, submucosa, muscularis, and serosa/adventitia.
• The epithelium is a nonkeratinized stratified squamous epithelium that serves a protective function in the mouth, oropharynx, esophagus, and anal canal.
• The movements of the muscularis mucosae ensure that all absorptive cells are fully exposed to the contents of the GI tract.
• Each of four spermatids develop into a sperm during spermatogenesis.
• The second meiosis division gives four spermatids, each with 23 single stranded chromosomes.
• The first meiosis division gives two secondary spermatocytes, each with 23 chromosomes that become double stranded.
• Esophageal stage involves a progression of coordinated contractions and relaxations of the circular and longitudinal layers of the muscularis, which pushes the bolus onward, taking 5-8 seconds.
• Mixing waves, gentle, rippling, peristaltic movements that pass over the stomach every 15 to 25 seconds, macerate food, mix it with secretions of the gastric glands, and reduce it to a soupy liquid called chyme.
• Peptic ulcer is caused when the gastric juices (acid and pepsin) digest the mucosal lining of the digestive tract.
• Esophageal stage is the passage of the bolus through the esophagus into the stomach.
• In the stomach, digestion of starch and triglycerides continues, digestion of proteins begins, the semisolid bolus is converted to a liquid, and certain substances are absorbed.
• Stomach has large folds, known as rugae, which increase surface area, and contain mucus neck cells, parietal cells, chief cells, G cells, and several other types of cells.
• Approximately 80% of peptic ulcers occur on the duodenal side of the pyloric sphincter, but peptic ulcers can also occur in the stomach (gastric ulcers) or esophagus (esophageal ulcers).
• Stomach connects the esophagus to the duodenum, the first part of the small intestine.
• Function of the stomach is to serve as a mixing chamber and holding reservoir.
• Stomach is a J-shaped enlargement of the GI tract directly inferior to the diaphragm in the abdomen.
• The primary spermatocyte with 2m=46 chromosomes and the spermatogonium with 2n=46 chromosomes multiply by mitosis.
• Sperm are adapted for reaching and fertilizing the egg, with the head containing DNA and the acrosome with enzymes for penetrating the egg, the midpiece containing mitochondria to form ATP for energy, and the tail being a flagellum used for locomotion.
• Accessory digestive organs include the teeth, tongue, salivary glands, liver, gallbladder, and pancreas, and they aid in the physical breakdown of food or produce or store secretions that flow into the GI tract through ducts, aiding in the chemical breakdown of food.
• Digestive enzymes produced by the salivary glands, tongue, stomach, pancreas, and small intestine catalyze these catabolic reactions.
• The movement of molecules out of the digestive tract and into the blood or into the lymphatic system is known as ABSORPTION.
• Mechanical and chemical processes break down ingested food into small molecules.
• In MECHANICAL DIGESTION, the teeth cut and grind food before it is swallowed, and then smooth muscles of the stomach and small intestine churn the food.
• The process by which the waste products of digestion are removed from the body is known as ELIMINATION, and it occurs primarily in the large intestine.
• Defecation is the process by which wastes, indigestible substances, bacteria, cells sloughed from the lining of the GI tract, and digested materials that were not absorbed in their journey through the digestive tract leave the body through the anus.