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Bio Unit 5 Terms
Human Biology 2 - Unit 5 Terms - Sophia
| Term | Definition |
|---|---|
| Acid-Base Balance | The amounts of acids and bases in the extracellular fluids of the body; amounts of acids vs. bases affects the overall pH of extracellular fluids. |
| Acids | Substances that increase the amount of hydrogen ions (H+) in a liquid and lower the pH. |
| Acromegaly | A condition in which growth hormone levels are too high after growth plates ossify; this causes bones to thicken and extremities to enlarge but bones cannot grow in length. The most prominent signs are enlarged facial features, hands and feet. |
| Adrenal Cortex | The outer covering of the adrenal gland that secretes hormones that regulate body mineral levels, metabolism and aid in the production of sex hormones. |
| Adrenal Glands | Located on top of the kidneys, the adrenal glands have two anatomic divisions: the adrenal cortex and the adrenal medulla. |
| Adrenal Medulla | The adrenal medulla is the inner ball of cells under the adrenal cortex. It releases hormones called catecholamines (adrenaline) that elevate metabolism in response to stress. It is controlled by the sympathetic nervous system. |
| Afterbirth | Occurs after the baby is expelled from the uterus, afterbirth is when the placenta separates from the uterine wall and is expelled from the mother. |
| Aldosterone | Nicknamed the “salt-retaining hormone," aldosterone stimulates the kidneys to retain sodium while simultaneously excreting potassium in the urine. |
| Allantois | An extension of the yolk sac, it provides oxygen to and removes waste from the early embryo & will become the umbilical cord's blood vessels. The amnion, chorion, yolk sac, and allantois form the sac that encloses the embryo within the uterus. |
| Alpha Cells | Cells of the pancreas that secrete glucagon. |
| Alzheimer’s Disease | A form of dementia that is caused by a degeneration of neurons and synapses of the cerebral cortex. This degeneration causes memory loss and other complications as the disease progresses. |
| Amniocentesis | The insertion of a need into the amnion. An amniocentesis is done in the 14-16th week of pregnancy if testing for genetic abnormalities is warranted. |
| Amnion | A sac or distinctive pouch that encloses the embryo and is filled with amniotic fluid that cushions and protects the embryo. The amnion, chorion, yolk sac and allantois together form the protective sac that encloses the embryo within the uterus. |
| Amylase | An enzyme that breaks down carbohydrates in the digestive system. |
| Andropause | Referred to as “male menopause”, andropause is when testosterone levels, libido and fertility decline with age; however males are still able to conceive a child (unlike women). |
| Anterior Lobe of Pituitary Gland | Also called the adenohypophysis, this lobe started developing in the nasopharynx and migrated up into the skull to join with the posterior lobe of the pituitary gland. Since it didn’t originate in the brain there are no direct neural connections to it. |
| Anterior Lobe of Pituitary Gland Secretions | The anterior pituitary gland secretes six hormones: growth hormone (GH), adrenocorticotropic hormone (ACTH), thyroid stimulating hormone (TSH), prolactin, luteinizing hormone (LH), and follicle stimulating hormone (FSH). |
| Antidiuretic Hormone (ADH) | A hormone secreted from the posterior pituitary gland that stimulates the kidneys to retain water. The receptors for are located on the distal convoluted tubules and collecting ducts. High levels cause urine to darken & output to decrease (concentrated). |
| Anus | The opening of the rectum, the anus is the last part of the alimentary canal through which fecal matter escapes. |
| Appendix | An organ located on the lower right side of the colon, the appendix contains lymph nodules called Peyer’s patches. Sometimes the appendix becomes inflamed and ruptures during a condition called appendicitis. |
| Bases | Substances that decrease the amount of hydrogen ions (H+) in a liquid and raise the pH. |
| Beta Cells | Cells of the pancreas which secrete insulin. |
| Bile | A secretion created by the liver that is used to aid in the digestion of lipids (fats). |
| Blastocyst | Roughly 5 days after implantation, a fluid-filled cavity will open up in the morula (ball of cells). This ball - with a thin layer of cells (the trophoblast) surrounding the cavity in which lies the inner cell mass - is called the blastocyst. |
| Blastomere | A cell that results from the cleavage of a zygote. |
| Body Mass Index (BMI) | A measurement ratio of your height and weight to assess a person’s body composition that is often used as a health and disease indicator. |
| Bolus | The ball of chewed food that is swallowed. |
| Bowman’s Capsule | A capsule that surrounds the glomeruli, Bowman’s capsule channels the filtered fluids from the glomerulus into the nephron. |
| Breech | When the fetus positions itself feet-first instead of head-first during labor. |
| Bulbourethral Gland (Cowper's Gland) | A gland that secretes substances to neutralize the acidity of remnants of urine in the urethra. |
| Carbohydrates | A class of organic compounds that are the body’s main source of energy; carbohydrates are sugars that can be found as monosaccharides (glucose), disaccharides (sucrose), and polysaccharides (starch). |
| Cell Differentiation | The process of cells taking on specific forms and functions; also called specialization of cells. |
| Cervix | The lower portion of the uterus which opens to the vagina. |
| Chancre | A painless genital ulcer. |
| Chemical Digestion | The breakdown of food by enzymes or chemicals. |
| Chlamydia | The most common STD in humans, Chlamydia is caused by a bacterium that infects the reproductive and urinary tracts. If left untreated, it can cause pelvic inflammatory disease. |
| Chorion | An outer membrane around the fetus that protects the fetus, absorbs blood from the mother to be transferred to the embryo and secretes HCG to prevent endometrial breakdown. |
| Chorionic Villus Sampling | A procedure done in the first 10-12 weeks to check for genetic disorders of the child; a tube with a suction cup at the end is inserted into the vagina toward the cervix to remove a sample of the chorion. |
| Chyme | The soupy mix that digested food is converted to in the stomach. |
| Cirrhosis | Scar tissue on the liver most oftenly due to heavy alcohol consumption over time. |
| Cleavage | A general term to describe the splitting or breaking apart of an object or molecule; in embryology, this is when the zygote starts to divide into multiple cells. |
| Collagen | The most abundant protein in the human body, collagen is a large fibrous structural protein found in many connective tissues. |
| Colorectal Cancer | Cancer of the colon or rectum. |
| Corpus Luteum | When the oocyte is released into the oviduct, the cells that nourished it remain in the ovary. They supply the uterus progesterone and estrogen, preparing the uterine lining (the endometrium) for a fertilized embryo to implant and develop. |
| Crohn's Disease | A disorder in which the intestine and other organs become frequently inflamed; as a result, a portion of the intestine may have to be removed. |
| Cystic Fibrosis | A genetic disorder in which the pancreas doesn't produce enzymes necessary to digest and absorb fats. |
| Delta Cells | Cells of the pancreas which secrete somatostatin. |
| Dialysis | The process of artificially filtering a person’s blood by pumping it out of their body and into a machine; dialysis is a necessary procedure for a person whose kidneys are failing or completely gone (failed). |
| Digestive System | A body system involved in digesting and absorbing foods. |
| Digestive Tract | Also known as the alimentary canal, it consists of the mouth, esophagus, stomach, small intestine, colon (large intestine), rectum and anus. These perform the main functions of the digestive system: ingestion, digestion, absorption, and excretion. |
| Distal Convoluted Tubule | The last tubular part of the nephron, the distal convoluted tubule contains receptors for the antidiuretic hormone (ADH) and aldosterone, which are both important for water and salt retention. |
| Diuretic | A medication or substance that increases a person’s urine output. |
| Duodenum | The first section of the small intestine, where most of the digestive enzymes are secreted. |
| Ectoderm | The outer germ layer that forms the nervous system, skin, melanocytes and lenses of the eyes. |
| Ectopic Pregnancy | Also called tubal pregnancy, an ectopic pregnancy occurs when implantation occurs in the oviduct instead of the uterus. Ectopic pregnancies result in abdominal pain that will eventually cause the oviduct to rupture if the pregnancy isn’t terminated. |
| Elastin | A thinner, “stringier” protein than collagen, elastin allows tissues to be stretched when pressure is applied to them and resume their shape once pressure is relieved. |
| Embryo | A stage of development of an individual, formed from the inner cell mass of a blastocyst after it has implanted in the uterus. |
| Embryonic Disk | Part of the inner cell mass of the blastocyst, the embryonic disk is the cellular framework that begins embryonic development; the nervous system develops from a cell layer within called the ectoderm. |
| Endocrine System | A system of glands that produces and secretes hormones into the bloodstream; the endocrine system is used to communicate on a broad scale to the cells in the body. |
| Endoderm | The innermost germ layer that forms the digestive tract, respiratory tract, endocrine glands, auditory systems, and urinary bladder. |
| Endometrium | The inner lining of the uterus. |
| Epididymis | The location where sperm mature and are stored after being produced. |
| Epiglottis | Covers the larynx during swallowing to prevent food or liquids from entering the lungs. |
| Epinephrine | Classified as a catecholamine (adrenaline) and is secreted from the adrenal medulla; epinephrine is found in higher amounts in the blood than its counterpart norepinephrine, and has slightly more of an effect on the heart. |
| Esophagus | A tube that carries food from the pharynx to the stomach. |
| Essential Amino Acids | Amino acids we cannot naturally synthesize are called essential amino acids; since we cannot synthesize them, we must consume them in our diet. |
| Essential Fatty Acids | Fatty acids we cannot naturally synthesize are called essential fatty acids; since we cannot synthesize them, we must consume them in our diet. |
| Estrogen | A female sex hormone that plays various roles in the female reproductive system, including preparing the endometrium for pregnancy. |
| Extracellular Fluids | Bodily fluids that are contained outside of cells. Major examples include blood plasma, saliva, and interstitial fluid, which surrounds the outside of cells. |
| FSH | Follicle stimulating hormone; a major hormone of the reproductive system which stimulates ovulation. |
| Female Reproductive System | Primary job is to mature and release oocytes (eggs) – process called oogenesis. Secondary functions are to gestate, nourish and deliver the child. Primary organs = ovaries. Accessory organs = vagina, cervix, uterus, fallopian tubes and breasts. |
| Fertilization | The process by which a male gamete (sperm) combines with a female gamete (egg/oocyte). |
| Fetal Alcohol Syndrome | A birth defect that leads to mental retardation due to the consumption of alcohol by the mother while pregnant. |
| Fetus | The developing baby after the first eight weeks of development up to birth. |
| Filtration | The first step in urine formation in which urine is filtered from afferent arterioles in the Bowman's capsule of a nephron. |
| First Trimester | Marks the start of the pregnancy through the first 13 weeks, where the fertilized egg implants in the uterus and develops into an embryo. |
| Follicle | The follicle consists of the maturing oocyte, along with surrounding cells that nourish the oocyte along its journey through the ovary. |
| Follicle Stimulating Hormone (FSH) | A hormone secreted by the anterior pituitary gland, FSH stimulates the production of gametes (sperm in males and oocytes in females). Secretion is regulated through negative feedback mechanisms and the gonadotropin-releasing hormone (GnRH). |
| Gallbladder | The organ that stores bile until we need to secrete it; bile is transported from the gallbladder into the duodenum through bile ducts. |
| Gametes | Cells (eggs or sperm) which contain half the DNA the rest of the body's (somatic) cells have. Thus, when two gametes (sperm and egg) combine, each with half the normal amount of DNA, the resulting embryo has the full complement of DNA. |
| Gastric Juice | The bath of secretions in the stomach that’s used to chemically digest food; contains hydrochloric acid (HCl), pepsins and salivary lipase. |
| Gastroesophageal Reflux Disease | A disorder in which chyme backs up in the esophagus due to the lower esophageal sphincter not closing properly. |
| Genital Herpes | A viral infection that can cause sores to develop on the mouth or reproductive organs, genital herpes is an incurable disease. |
| Genital Warts | Caused by the human papilloma virus (HPV), genital warts appear on reproductive organs and the anus and can increase the chance of developing certain cancers. |
| Germ Layers | The first three layers of tissue that develops in the embryo as it starts to form (ectoderm, mesoderm, and endoderm). |
| Gigantism | A condition in which growth hormone levels are too high at an age before growth plates ossify; this causes bones and other tissues to grow proportionally larger than average. |
| Gland | Glands are clusters of cells that produce and secrete specific molecules. Endocrine glands secrete hormones directly into the bloodstream, where they can quickly reach their target cells anywhere in the body. |
| Glomerulus | The tufts of capillaries in the kidneys where the filtration of blood occurs; glomeruli have unique filtering membranes that repel cells and proteins and allow only small substances (water, electrolytes, wastes, etc.) to be filtered out of blood. |
| Glucagon | A hormone released by alpha cells in the pancreas which raises blood sugar levels. |
| Glucocorticoids | Hormones that affect glucose metabolism of the body, the most abundant one being cortisol a.k.a. the stress hormone. |
| Gluconeogenesis | The process of converting amino acids and lipids into glucose, this process takes place in the liver. |
| Gonadotropin-releasing Hormone (GnRH) | A hormone secreted by the hypothalamus that stimulates the anterior pituitary gland to secrete FSH and LH. |
| Gonorrhea | Commonly referred to as "the clap", gonorrhea is a bacterial infection that can cause painful urination and penile discharge in males and vaginal discharge in females. |
| Graves Disease | Graves disease is the most common form of hyperthyroidism (where the thyroid gland becomes overactive). It is an autoimmune disease in which the thyroid over-secretes T₃ and T₄ hormones. |
| Hepatic Portal System | A system of veins that drain blood from the stomach and intestines to the liver; a portal system consists of two consecutive capillary beds connected by a portal vein(s). |
| Hepatitis | A disease that causes inflammation of the liver and can lead to malfunctioning of the liver if left untreated. |
| Hepatitis B | A retroviral infection of the liver that is spread through sexual contact. It is very curable in adults. |
| Hormones | The major chemical messenger (derived from either amino acids or lipids) of the endocrine system. Hormones are produced, stored and secreted by glands; hormones either increase or decrease activity of the cells with which they interact. |
| Human Chorionic Gonadotropin (HCG) | A hormone secreted from the developing placenta(blastocyst) that prevents the destruction of the corpus luteum; the corpus luteum secretes estrogen and progesterone which prepares the female’s body for pregnancy. |
| Hypoglycemia | The clinical term for low blood sugar. |
| Hypothalamus | The hypothalamus is at the "basement" of the forebrain, between the cerebrum and the midbrain/brainstem. The hypothalamus controls the activity of the pituitary gland. |
| Ileum | The last section of the small intestine which connects to the large intestine, where most of the lipids are absorbed. |
| Implantation | A term used to describe when the blastocyst attaches to the endometrium of the uterus. |
| Inner Cell Mass | A layer of the blastocyst which will develop into an embryo. |
| Insulin | A hormone released by beta cells in the pancreas which lowers blood sugar levels. |
| Jejunum | The middle section of the small intestine, where most of the absorption of carbohydrates and proteins occurs. |
| Kidney Cancer | Cancer that occurs in the kidneys; it is more prevalent in males than in females. |
| Kidney Stones | Deposits of acids and salts that accumulate in the kidneys and can obstruct the flow of urine; kidney stones are very painful to void. |
| Kidneys | Two bean-shaped organs in the upper posterior abdominal cavity (retroperitoneal) that regulate the composition and volume of bodily fluids by filtering blood and creating urine. |
| LH | Luteinizing hormone; a hormone released from the anterior pituitary gland and plays a large role in the reproductive system. |
| Lactation | The secretion of milk from the mammary glands, hormonally stimulated by oxytocin. |
| Lactose Intolerance | A disorder in which the lactase enzyme is deficient, so lactose cannot be digested and absorbed properly. |
| Large Intestine | A tube attached to the small intestine where remaining nutrients and water are absorbed before waste is passed. |
| Large Intestine/Colon | The last major tubular organ of the alimentary canal, it forms a frame around the small intestine. The colon is responsible for absorbing water and minerals and converting the bolus into fecal matter. |
| Leydig Cells | Cells of the testes that release testosterone. |
| Lipase | An enzyme that breaks down fats in the digestive system. |
| Lipids | Long hydrophobic hydrocarbon chains that act as the body’s main source of stored energy along with other secondary functions. |
| Liver | Produces bile and secretes it into the gallbladder to be stored. The liver also processes nutrients such as amino acids and carbohydrates, and also “detoxifies” the blood. |
| Loop of Henle | The second tubular part of the nephron, the loop of Henle dips down into the renal medulla and is the site where water conservation in the nephron occurs. |
| Lumen | The name used to describe the hollow part of a hollow/tubular organ. |
| Luteinizing Hormone (LH) | A hormone secreted by the anterior pituitary gland, LH stimulates Leydig cells to secrete testosterone while in females it promotes ovulation. |
| Male Reproductive System | Primarily designed to produce and mature gametes (sperm) and deliver them to the female they are mating with. |
| Male Reproductive System Organs | Primary organs of the male reproductive system are the testes, while the secondary organs would be the epididymis, vas deferens, seminal vesicles, bulbourethral glands, prostate gland, urethra and the penis. |
| Mechanical Digestion | The physical breakdown of food into smaller pieces. |
| Menarche | A woman's first menstrual cycle. |
| Menopause | Marks the end of a woman's fertility in which a woman is no longer able to conceive. |
| Menstrual Cycle | Monthly cycle in which an oocyte matures and is released from a woman's ovary. |
| Menstruation | The flow of the endometrium out the vagina if the oocyte was not fertilized during the menstrual cycle. |
| Mesoderm | The middle germ layer that forms cartilage, bone, muscle, connective tissue, cardiovascular system, lymphatic system, urinary system, respiratory system, and the outer layer of the digestive tract. |
| Microvilli | Hair-like projections that cover villi and aid in absorption of nutrients. |
| Mineralcorticoids | Hormones that maintain mineral homeostasis; aldosterone is a hormone that stimulates the kidneys to retain sodium. |
| Minerals | Inorganic elements (often found in salts) that are involved in almost every metabolic process of the human body. |
| Miscarriage | Also called spontaneous abortion, a miscarriage is when the embryo is expelled from the uterus. |
| Morphogenesis | When an organism develops a specific shape. |
| Mouth | The location where food enters and digestion begins. |
| Mucosa | The mucous membranes of the alimentary canal. This is the layer of tissue of the alimentary canal that is in direct contact with its lumen. |
| Nephritis | Inflammation of the kidneys caused by infections or autoimmune disorders. |
| Nephron | Microscopic tubes within the kidneys that filter blood and produce urine. Nephrons are made up of five parts: the Bowman’s capsule, the proximal convoluted tubule, the loop of Henle, the distal convoluted tubule, and collecting ducts. |
| Neural Tube | A tube formed from the ectoderm of the blastocyst that serves as the framework for the development of the central nervous system (brain and spinal cord). |
| Non-Steroid Hormones | Hormones that are primarily derived from proteins, are water soluble, & are transported freely through the blood. They interact with receptors on the cell membrane & activate secondary messenger systems to carry out effects within the cell. |
| Norepinephrine | Classified as a catecholamine (adrenaline) and is secreted from the adrenal medulla; norepinephrine is found in lower amounts in the blood than its counterpart epinephrine, and has slightly more of an effect on the blood vessels. |
| Obesity | Having too much body fat. This is not to be confused with being overweight, which means weighing too much. Obesity is a risk factor for many chronic diseases such as hypertension, type II diabetes, cardiovascular disease, etc. |
| Oocytes | Immature form of ova (eggs cells) that are released from ovaries. |
| Oogenesis | The process by which egg cells are formed. |
| Opposing Interaction | A term used to describe hormones that create opposite effects of one another. An example would be: insulin lowers blood glucose while glucagon elevates blood glucose. |
| Ovarian Cycle | The cycle in which an oocyte matures as the menstrual cycle advances. |
| Ovaries | Female reproductive organs that produce oocytes. |
| Oviduct | A duct that connects ovaries to the uterus through which egg cells travel; also called "fallopian tubes". |
| Ovulation | The process of expelling the oocyte from the ovary to the oviduct. |
| Ovum | A mature egg cell (the plural of "ovum" is "ova"). |
| Oxytocin | A hormone secreted from the posterior pituitary gland (neurohypophysis) via a positive feedback mechanism once the child begins to put pressure on the cervix of the uterus. |
| Palate | Also known as the "roof" of your mouth; The tongue presses food against the palate and mixes it with saliva to break it down before swallowing. |
| Pancreas | The endocrine functions of the pancreas are to secrete insulin and glucagon to regulate blood glucose levels. |
| Pancreatic Islets | Small clusters of cells on the pancreas containing cells that manufacture the hormones insulin and glucagon, along with many secretions for the digestive system; also referred to as the islets of Langerhans. |
| Parathyroid Glands | A group of glands on the posterior thyroid that secrete parathyroid hormone to increase blood calcium levels by decreasing renal excretion of calcium and increasing osteoclast activity. |
| Pelvic Inflammatory Disease | Inflammation of the uterus, fallopian tubes/oviducts and/or ovaries that can lead to scarring and damage. |
| Penis | The male sex organ. |
| Pepsins | Enzymes that are responsible for digesting proteins into amino acids within the stomach. |
| Peristalsis | Wave-like muscle contractions. |
| Peritubular Capillaries | Capillaries associated with nephrons which allow water and solutes to be exchanged between the nephron and the blood during urine formation. |
| Permissive Interaction | When one hormone allows another hormone to have its full effect. An example would be: thyroid hormones allowing growth hormone to have its full metabolic effects. |
| Pharynx | Also known as the throat. Food moves from the mouth to the pharynx as a person begins to swallow. |
| Pineal Gland | A gland located in the cerebrum that secretes melatonin, an important hormone for regulating sleep/wake cycles. |
| Pituitary Dwarfism | A condition in which growth hormone levels are too low at a young age and the person is proportionally smaller than normal. |
| Pituitary Gland | Called the “master gland” because of its effects on other glands; endocrine hormones increase activity/secretion of many major glands of the endocrine system. |
| Placenta (early stage) | The blastocyst consists of the thin outer layer of cells (the trophoblast) surrounding a cavity within which is the inner cell mass (which will become the embryo). The trophoblast becomes the placenta. |
| Placenta (later stage) | The trophoblast becomes the placenta, which connects the fetus via the umbilical cord to the uterus. The placenta provides nutrients, gas exchange and waste elimination via the mother's blood supply. |
| Posterior Lobe of Pituitary Gland | Also called the neurohypophysis, it developed from brain tissue during embryonic development and therefore is directly innervated by the hypothalamus. The two hormones the posterior pituitary secretes are anitdiuretic hormone (ADH) and oxytocin. |
| Prediabetes | The signs and symptoms leading up to diabetes. |
| Preimplantation Diagnosis | The screening of embryos before in vitro fertilization to ensure they are genetically fine before they are implanted into the mother. |
| Progesterone | A hormone released during the menstrual cycle that prepares the endometrium for implantation. |
| Prostaglandins | A group of lipid-based chemical messengers in the body, prostaglandins during labor promote uterine contractions. |
| Prostate Cancer | Cancer of the prostate gland. |
| Prostate Gland | A gland which produces and secretes substances that buffer the acidity of the female reproductive tract to ensure ideal conditions for sperm. |
| Protein | Large, complex polymers of amino acids that have diverse functions (structure, communication, identity, immunity, carriers, etc.) |
| Proximal Tubule | The first tubular part of the nephron, the proximal convoluted tubule is where the majority of reabsorption of wanted materials back into the blood occurs and conversely where most secretion out of the nephron occurs. |
| Reabsorption | The second step in urine formation in which valuable water and solutes are reabsorbed back into the blood. |
| Rectum | The digestive system analog to the urinary bladder, the rectum stores fecal matter until it’s time to excrete it from the body. |
| Renin | An enzyme found in blood that plays an important role in increasing blood pressure during hemorrhaging and diarrhea. |
| Rubella | A virus that can be contracted by a pregnant mother and lead to improper organ development of the baby; also known as German measles. |
| Salivary Amylase | An enzyme found in saliva that chemically breaks down starches into simple sugars. |
| Salivary Glands | Glands in the mouth which release saliva to aid in the chemical digestion of foods while you chew. |
| Second Trimester | Marks the start of the fourth month until the end of the sixth month of pregnancy in which the fetus continues to develop as organs and organ systems mature. |
| Secondary Messenger | Signaling molecules located near a hormone receptor on the inside of the cell; when a non-steroid hormone binds to its receptor outside the plasma membrane, it activates secondary messenger systems that carry out specific effects inside of the cell. |
| Secondary Sexual Traits | Traits controlled by testosterone such as deepening of the voice and facial hair development during puberty. |
| Secretion | The third step in urine formation in which filtrate moves toward collecting ducts; secretion helps maintain the body's acid-base balance. |
| Semen | A combination of sperm and other glandular secretions that is expelled from the penis during sexual activity. |
| Seminal Vesicle | A component of the male reproductive system which secretes fructose, which is used by sperm as a source of energy. |
| Seminiferous Tubules | Tubules within chambers of the testes in which sperm are produced. |
| Senescence | The technical term for aging. |
| Serosa | The outermost layer of tissue of the alimentary canal that produces a watery secretion to reduce friction while digestive organs are moving. |
| Sex Chromosomes | The X & Y chromosomes that when paired determine the gender of the child and carry other genetic traits as well; XX = female while XY = male. |
| Sexual Intercourse | The process in which semen is ejaculated from the male penis into the female vagina which can result in the fertilization of an egg cell. |
| Simple Goiter | A non-cancerous enlargement of the thyroid gland that can sometimes occur on its own or when a person is lacking in iodine and the thyroid hormones. |
| Small Intestine | A long tube in which food passes through as nutrients are absorbed. |
| Smooth Muscle | A form of muscle that contains short, tube-like (fusiform) single-nucleated cells; smooth muscle range from having many layers to a single layer of cells; smooth muscle is found in the walls of hollow organs. |
| Somatostatin | The exact function of this hormone is not well understood, but it’s believed that it may help regulate alpha and beta cell activity along with some digestive functions. |
| Sperm | The male gamete, sperm, has only half the normal amount of DNA. If a sperm fertilizes the female gamete (egg aka oocyte), the fertilized embryo will have the correct amount of DNA (1/2 from the sperm + 1/2 from the egg = 1 tiny human). |
| Spermatogenesis | The process of sperm formation. |
| Sphincters | Muscles that control the openings between organs; sphincters control what enters and exits various organs. |
| Spina Bifida | A condition in which lack of folic acid intake by the mother. This lack of folic acid can lead to the neural tube not closing and a portion of the spinal cord being exposed on the child. |
| Sterility | The inability to reproduce. In men, this means an inability to fertilize oocytes; in women, this is either an inability to produce healthy oocytes or an inability to gestate a baby. |
| Steroid Hormones | Hormones that have a cholesterol backbone and are not soluble in water (lipids). They are transported through the blood by carrier proteins. They penetrate the cell membrane and interact with nuclear receptors that affect the DNA. |
| Stomach | The area where food is stored as well as chemically and mechanically digested before moving into the small intestine. |
| Submucosa | The layer of tissue just below the mucosa, the submucosa contains glands that secrete onto the mucosa. The submucosa also contains capillaries and lymph vessels. |
| Synergistic Interaction | Used to describe hormones that create similar effects through slightly different mechanisms. An example would be: ADH stimulating kidneys to retain water while aldosterone stimulates kidneys to retain sodium, which in turn retains water. |
| Syphilis | Caused by bacteria, syphilis initially presents as a rash or skin lesions, and if left untreated can cause cardiovascular damage and insanity. |
| Target Cell | The cell or group of cells with which a hormone is designed to interact. |
| Teratogen | Anything that can cause or contribute to the development of a birth defect. |
| Testes | The primary sex organs of males, and are their primary source of testosterone. The testes are also where the sperm is produced and matured. |
| Testosterone | The male sex hormone that controls the development of the male reproductive system, as well as many tissues in both the male and female body. |
| Third Trimester | Marks the seventh month of pregnancy until birth, and is characterized by the continued development of the fetus as it prepares for birth. |
| Thymus Gland | A gland located above the heart. It secretes thymosins, which mature the immune system's T-cells. |
| Thyroid Gland | Located on the anterior trachea, it secretes hormones that regulate metabolism. It also secretes a hormone called calcitonin that lowers blood calcium levels by increasing the kidneys' excretion of calcium and inhibiting osteoclasts. |
| Toxoplasmosis | A condition in which parasitic cysts from exposure to cat feces can infect the mother and fetus, causing birth defects or miscarriage. |
| Trichomoniasis | A protozoan parasite that commonly causes inflammation of the vagina in females. |
| Tubular Reabsorption | The second step in urine formation in which water and valuable solutes are reabsorbed from the nephron into the bloodstream. |
| Tubular Secretion | The third step in urine formation, which is the process of secreting materials (wastes, acids) from peritubular capillaries into the nephron that weren’t filtered at the glomerulus. |
| Type I Diabetes | AKA juvenile-onset diabetes or insulin dependent diabetes mellitus (IDDM), this is an autoimmune disease in which the immune system destroys the pancreas's beta cells. Type I is early onset and requires insulin injections. |
| Type II Diabetes | AKA adult-onset diabetes or non-insulin dependent diabetes mellitus (NIDDM), type II diabetes is more of a lifestyle disease that affects people when they are older. People with type II produce and secrete insulin but cannot regulate blood sugar well. |
| Umbilical Cord | The cord that connects the embryo to the placenta, the umbilical cord carries nutrients to the child and wastes away. |
| Ureters | Tubular organs that carry urine from the kidneys to the urinary bladder. |
| Urethra | A hollow, tubular organ that carries urine out of the body as it is expelled from the urinary bladder. |
| Urinary Bladder | A sac-like organ that stores urine until it can be expelled from the body (a process called urination or micturition). |
| Urinary System | An organ system that filters metabolic waste and excessive materials (like water and electrolytes) from the blood and expels them from the body. The major organs of the urinary system are the kidneys, ureters, urinary bladder, and urethra. |
| Urinary Tract Infection (UTI) | Infections that enter the urethra and can climb as high as the kidneys; UTIs cause inflammation of the urinary bladder or kidneys. |
| Urination | A reflex that occurs when the urinary bladder fills to capacity and is stimulated to empty itself. |
| Urine | A substance made up of metabolic waste and excess materials (like water and electrolytes) from the blood, created by the kidneys and expelled from the body. |
| Uterus | An organ of the female reproductive system in which fertilized eggs develop into an embryo. |
| Vagina | The organ of the female reproductive system which serves as the location where sperm enter and also serves as the birth canal. |
| Vas Deferens | A tube that carries sperm from the epididymis during sexual arousal. |
| Villi | Small finger-like projections that line the mucosa and act to increase surface area and absorb nutrients. |
| Vitamins | A diverse class of organic compounds that usually assist enzymes (in pretty much every metabolic function). |
| Yolk Sac | A membranous sac attached to the embryo that provides early nourishment and develops the cardiovascular system; the yolk sac eventually disintegrates. |
| Zona Pellucida | A protein layer that surrounds the follicle. |
| Zygote | The first cell of an individual formed when a sperm cell fertilizes an egg cell. |
| pH | A measure of whether a liquid has a lot of hydrogen ions (H+) or relatively few. The lower the pH, the more hydrogen ions it has, and the more acidic it is. The higher the pH, the fewer hydrogen ions it has, and the more basic it is. |
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