Phlebotomy Technician

The menstrual cycle averages 28 days and consists of three phases.

The follicular phase (days 1-13) begins with menstruation. FSH stimulates follicle development in the ovaries. One dominant follicle matures while others degenerate. The maturing follicle produces estrogen, which stimulates endometrial thickening.

Ovulation (day 14) occurs when LH surge triggers release of the mature oocyte from the ovary. The oocyte enters the fallopian tube.

The luteal phase (days 15-28) follows ovulation. The empty follicle becomes the corpus luteum, producing progesterone and estrogen. Progesterone maintains the endometrium for potential implantation. If pregnancy does not occur, the corpus luteum degenerates, hormone levels drop, and menstruation begins.

Estrogen is produced primarily by the ovaries. Functions include development of female secondary sex characteristics, regulation of menstrual cycle, maintenance of bone density, and cardiovascular protection.

Progesterone is produced by the corpus luteum and placenta during pregnancy. It prepares the endometrium for implantation and maintains pregnancy.

Human chorionic gonadotropin (hCG) is produced by the placenta after implantation. It maintains the corpus luteum during early pregnancy. Detection of hCG in blood or urine confirms pregnancy.

Pregnancy tests detect hCG in serum or urine. Quantitative serum hCG tests measure exact levels and monitor pregnancy progression. Timing of specimen collection affects result interpretation.

Hormone panels evaluate reproductive function. Tests include FSH, LH, estrogen, progesterone, and prolactin. Specimen collection timing relative to the menstrual cycle is important.

Pap smears screen for cervical cancer but are collected by trained healthcare providers, not phlebotomists. Phlebotomists may collect blood specimens for HPV testing.

Prenatal testing evaluates maternal and fetal health. Common tests include complete blood count (CBC), blood type and Rh factor, antibody screening, rubella immunity, hepatitis B surface antigen, HIV, syphilis, and glucose tolerance testing.

First trimester screening combines blood tests (PAPP-A, hCG) with ultrasound to assess chromosomal abnormality risk. Second trimester screening (quad screen) measures AFP, hCG, estriol, and inhibin A.

Glucose tolerance testing screens for gestational diabetes. Patients drink a glucose solution, and blood specimens are collected at timed intervals. Proper timing and specimen handling are critical.

Rh incompatibility occurs when an Rh-negative mother carries an Rh-positive fetus. The mother may develop antibodies against fetal red blood cells. RhoGAM (Rh immune globulin) prevents sensitization.

Sexually transmitted infections (STIs) require laboratory testing for diagnosis. Tests include HIV, hepatitis B and C, syphilis (RPR, VDRL, FTA-ABS), gonorrhea, chlamydia, and herpes. Confidentiality is paramount when collecting specimens for STI testing.

Infertility evaluation involves testing both partners. Female tests include hormone levels, ovarian reserve testing (AMH, FSH), and imaging. Male tests include semen analysis and hormone levels.

Menopause marks the end of reproductive function. Hormone levels change significantly. FSH levels increase while estrogen levels decrease. Hormone replacement therapy may be monitored through laboratory testing.

The digestive system breaks down food into nutrients that can be absorbed and used by cells. Functions include ingestion, mechanical digestion, chemical digestion, absorption, and elimination. The digestive system consists of the alimentary canal (gastrointestinal tract) and accessory organs.

The mouth is where digestion begins. Teeth mechanically break down food through mastication (chewing). The tongue manipulates food and contains taste buds. Salivary glands (parotid, submandibular, sublingual) produce saliva containing amylase, which begins carbohydrate digestion.

The pharynx (throat) is a common passageway for food and air. The epiglottis covers the larynx during swallowing to prevent aspiration. The esophagus is a muscular tube connecting the pharynx to the stomach. Peristalsis (rhythmic muscle contractions) moves food toward the stomach. The lower esophageal sphincter prevents stomach contents from refluxing.

The stomach is a J-shaped organ in the upper left abdomen. It stores food, mechanically churns contents, and begins protein digestion. The stomach wall has four layers and contains rugae (folds) that allow expansion.

Gastric glands produce gastric juice containing hydrochloric acid (HCl), pepsinogen, intrinsic factor, and mucus. HCl activates pepsinogen to pepsin and kills microorganisms. Intrinsic factor is essential for vitamin B12 absorption in the small intestine.

The pyloric sphincter controls release of chyme (partially digested food) into the small intestine.

The small intestine is approximately 20 feet long and consists of three sections: duodenum, jejunum, and ileum. Most chemical digestion and nutrient absorption occurs here.

The duodenum receives chyme from the stomach and secretions from the pancreas and liver. Pancreatic juice contains enzymes for digesting carbohydrates, proteins, and fats. Bile from the liver emulsifies fats.

The intestinal wall contains villi and microvilli, which dramatically increase surface area for absorption. Nutrients pass through the intestinal wall into blood and lymph capillaries.

The large intestine (colon) is approximately 5 feet long. Sections include the cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anal canal.

Functions include water and electrolyte absorption, vitamin K and B vitamin production by bacteria, and feces formation and storage. Bacteria in the colon constitute the gut microbiome, which influences digestion, immunity, and overall health.

The liver is the largest internal organ, located in the upper right abdomen. It has numerous functions critical to metabolism and homeostasis.

Digestive functions include bile production and secretion. Bile contains bile salts that emulsify fats, making them accessible to digestive enzymes. Bile also contains bilirubin, a breakdown product of hemoglobin.

Metabolic functions include carbohydrate metabolism (glycogenesis, glycogenolysis, gluconeogenesis), protein metabolism (albumin synthesis, deamination), and lipid metabolism (cholesterol synthesis, lipoprotein production).

The liver detoxifies drugs, alcohol, and metabolic waste products. It stores vitamins (A, D, E, K, B12) and minerals (iron, copper). It produces clotting factors and other plasma proteins.

Liver function tests (LFTs) evaluate hepatic health. Tests include ALT, AST, ALP, GGT, bilirubin, albumin, and prothrombin time. Specimen collection requires proper technique to avoid hemolysis, which can falsely elevate certain values.

The gallbladder is a small sac beneath the liver that stores and concentrates bile. When fats enter the duodenum, cholecystokinin (CCK) stimulates gallbladder contraction, releasing bile through the common bile duct.

Gallstones (cholelithiasis) can obstruct bile flow, causing pain and jaundice. Laboratory tests include bilirubin, liver enzymes, and amylase/lipase if pancreatitis is suspected.

The pancreas is located behind the stomach and has both exocrine and endocrine functions.

Exocrine function involves producing pancreatic juice containing digestive enzymes. Amylase digests carbohydrates, lipase digests fats, and proteases (trypsin, chymotrypsin) digest proteins.

Endocrine function involves producing hormones in the islets of Langerhans. Alpha cells produce glucagon, and beta cells produce insulin. These hormones regulate blood glucose levels.

Pancreatitis is inflammation of the pancreas. Laboratory diagnosis includes elevated amylase and lipase levels. Lipase is more specific for pancreatic damage. Proper specimen handling prevents enzyme degradation.

Carbohydrate digestion begins in the mouth with salivary amylase. Pancreatic amylase continues breakdown in the small intestine. Brush border enzymes (maltase, sucrase, lactase) complete digestion to monosaccharides (glucose, fructose, galactose). Monosaccharides are absorbed into blood capillaries.

Lactose intolerance results from lactase deficiency. Lactose tolerance tests and hydrogen breath tests diagnose this condition.

Protein digestion begins in the stomach with pepsin. Pancreatic proteases continue breakdown in the small intestine. Brush border peptidases complete digestion to amino acids. Amino acids are absorbed into blood capillaries.