Key Concepts in Human Anatomy and Physiology

Topographic Anatomy

Focuses on descriptive terminology used to define body areas and movements, which is important in the medical profession for accurate communication about patient assessment and care procedures.

Anatomical Anatomy

Uses specific terms to describe anatomical relationships based on a reference point, which in medicine is the anatomical position.

Anatomical Position

A diagram of a human body standing upright, with arms at the sides and palms facing forward, used as the reference point for describing anatomical relationships.

Anterior (ventral)

Located at or toward the front of the body or body part. Example: The stomach is anterior to the kidneys.

Posterior (dorsal)

Located at or toward the back of the body or body part. Example: The spine is posterior to the sternum.

Medial

Located at or near the midline of the body or body part. Example: The sternum is medial to the ribs.

Lateral

Located away from the midline of the body or body part and toward the side of the body or body part. Example: The ribs are lateral to the sternum.

Superior

Located toward the head or area of the body that is closer to the head. Example: The stomach is superior to the cecum.

Inferior

Located toward the feet or area of the body that is closer to the feet. Example: The cecum is inferior to the liver.

Proximal

Located toward or closer to a given point or origin, usually in relation to the trunk or midline of the body. Example: The pelvis is proximal to the leg.

Distal

Located farther from a given point of origin, usually used in relation to the trunk or midline of the body. Example: The hand is distal to the elbow.

Range of Motion

The range, measured in degrees of a circle, through which a body part can be rotated, extended, or flexed at a joint.

Longitudinal Axis

An imaginary line that passes lengthwise through a portion of the body or a bone, dividing the part equally and symmetrically.

Axis of Joint Rotation

A line projecting at right angles to the plane of motion; for most joints, it changes with the joint's motion due to its structure and variety of angles.

Rotation

A joint motion where a part moves or turns about its longitudinal axis. Example: Turning the head from side to side.

Circumduction

A movement where the distal end of a part makes a circle while the proximal portion remains relatively stationary. Example: Making circles with the entire arm stretched out.

Supination

The movement that rotates the forearm outward so that the palm of the hand faces forward. Example: Rotating palms forward while arms hang loosely at the side.

Pronation

The movement that rotates the forearm inward, causing the back of the hand to face forward. Example: Rotating palms toward the back of the body while arms hang loosely at the side.

Flexion

A motion described when adjacent body parts approach each other, decreasing the angle between them; the act of folding, bending, or withdrawing a body part. Example: Moving the forearm toward the head by bending the elbow.

Dorsiflexion

A special type of flexion for ankle and foot movement where the top (dorsal) surface of the foot moves closer to the leg, decreasing the angle between the anterior surface of the leg and the foot. Example: Pointing the toes toward the face.

Plantar Flexion

Another type of flexion for ankle/foot movement where the bottom (plantar) surface of the foot moves away from the leg, increasing the angle between the anterior surface of the leg and the foot. Example: Pointing the toes away from the face.

Extension

A movement that increases the angle between two adjacent body parts, causing parts of an extremity to line up in a straight manner. Example: Bringing arms straight to the side from an outward or forward position.

Hyperextension

A type of extension where a body part is extended or stretched beyond its normal anatomical position. Example: Moving the head backward as if looking up at the sky.

Abduction

Movement of a body part away from the midline or medial plane of the body.

Adduction

Movement of a body part toward the midline or medial plane of the body. Example: Bringing the arm from shoulder level back to the side.

Inversion

A special term describing the movement that turns the bottom of the foot inward. Example: Turning the soles of the feet toward each other.

Eversion

A special term describing the movement that turns the bottom of the foot outward. Example: Turning the soles of the feet away from each other.

Water (Human Body Fluid Constituent)

Composes about 60% of the human body fluid, aiding in substance transportation through cellular membranes and throughout the body, regulating body temperatures, and balancing hydrogen molecules. It also acts as a medium for enzymes breaking down particles during digestion.

Electrolytes (Human Body Fluid Constituent)

Chemical substances (ions) capable of carrying an electrical charge in water, found in the body's extracellular and intracellular spaces, and requiring a unique balance between them.

Fluid Volume Deficit (FVD) / Hypovolemia

A fluid imbalance caused by insufficient fluid intake or fluid loss (e.g., sweating, vomiting, diarrhea, severe burns, bleeding, bowel obstructions, excessive gastrointestinal suctioning). Signs include poor skin turgor, concentrated urine (high specific gravity), oliguria, dry mucous membranes, weak/rapid pulse, orthostatic hypotension, low central venous pressure, and in severe cases, confusion and restlessness. Treatment involves encouraging fluid intake or IV therapy; for severe bleeding, maintaining body temperature and oxygen.

Fluid Volume Excess (FVE) / Hypervolemia

A fluid imbalance caused by disease processes (e.g., congestive heart failure, renal failure, cirrhosis, Cushing's syndrome), excessive intake of parenteral fluids or salt, and decreased renal function with excess/normal fluid intake. Signs include edema, ascites, pulmonary edema, weight gain, distended neck veins, high central venous pressure, and a full, bounding pulse. If due to decreased renal function, polyuria and diluted urine are observed.

Sodium (Na)

The main cation (positively charged ion) found in extracellular fluid, essential for normal nerve and muscle activity and fluid balance regulation. Normal serum concentration is 135 to 145 mEq/L.

Hyponatremia (Sodium Deficit)

can result from profuse sweating (diaphoresis), vomiting, loss of gastric secretions from suctioning, and administration of nonelectrolyte intravenous fluids. Symptoms include confusion, lethargy, muscle cramps, and tremors.

Potassium (K)

A cation found in intracellular fluids, essential for normal nerve and muscle activity. It has functions intracellularly similar to sodium extracellularly. Normal serum potassium ranges from 3.5 to 5.0 mEq/L. Abnormal levels can cause death, especially in cardiac patients.

Hypokalemia (Potassium Deficit)

can occur with the use of certain diuretics (e.g., Lasix), fluid loss from vomiting and diarrhea, and gastric suctioning. Symptoms include fatigue, weakness, anorexia, nausea, vomiting, and dysrhythmias. Severe cases can lead to hypotension and death from cardiac or respiratory arrest. Treatment includes dietary supplements of potassium-rich foods (fruits) or oral/intravenous potassium salt.

Hyperkalemia (Potassium Excess)

can result from severe renal failure, severe burns, overuse of potassium supplements, and over-administration of parenteral potassium. Symptoms include diarrhea, nausea, muscle weakness, and dysrhythmias. Severe cases can lead to death from cardiac or respiratory arrest. Treatment ranges from removing potassium from the diet to special medications to lower serum potassium levels.

Calcium (Ca)

Found mostly in bones and teeth, regulated by the parathyroid glands. Serum levels account for only 1% of the body's total calcium. It is necessary for nerve impulse transmission, blood clotting, and muscle contraction. Normal serum levels range from 8.4 to 10.6 mg/dL.

Hypocalcemia (Calcium Deficit)

resulting from insufficient dietary intake of calcium, vitamin D deficiency (needed for calcium absorption), metastatic cancer attacking bone, or damage/removal of parathyroid glands causing hormone deficiency.

Hypercalcemia (Calcium Excess)

resulting from tumors on parathyroid glands, multiple fractures, excessive vitamin D doses, prolonged immobilization, and some antineoplastic drugs. Symptoms include deep bone pain, constipation, anorexia, nausea, vomiting, polyuria, polydipsia, fractures, and mental changes. Treatment involves determining and eliminating the cause, limiting calcium intake, forcing fluids, or administering IV fluids to increase calcium excretion.

pH (Acid-Base Balance)

Refers to the percentage of hydrogen ions present in a solution. More hydrogen ions mean a more acidic solution, while fewer mean a more alkaline solution.

Normal Plasma pH

Ranges from 7.34 to 7.45, indicating a slightly alkaline state. Results below 7.34 are considered acidic, and above 7.45 are considered alkaline.

Metabolic Acidosis

A deficit of bicarbonate (base) or a gain in acid in the body fluid, often resulting from an imbalance in food/fluid metabolism (e.g., diabetes). Causes include starvation, insulin deficiency leading to diabetic acidosis, diarrhea, and renal failure. Patient's serum pH is below 7.34. Treatment involves eliminating the cause, replacing lost fluids and electrolytes, and potentially administering bicarbonate.

Metabolic Alkalosis

An excess of bicarbonate (base) in the body fluids, which can result from gastrointestinal problems (e.g., chronic/excessive vomiting), ingestion of too many alkalies (e.g., antacids), or excessive gastric suctioning removing too much hydrochloric acid. Treatment involves eliminating the cause.

Respiratory Acidosis

Results from an excess of carbonic acid in the body fluids, caused by any deficiency in respiratory ventilation (e.g., pneumonia, emphysema, asthma, respiratory obstruction). Treatment is individualized and depends on the cause, often involving medications like bronchodilators to improve respiratory efficiency.

Respiratory Alkalosis

Results from a deficiency of carbonic acid, primarily due to hyperventilation ('blowing off' excessive CO2). Patients hyperventilate due to anxiety, high fevers, and hysteria. Treatment focuses on correcting hyperventilation, such as rebreathing expired air from a paper bag.

Thermal Regulation

The body's process of maintaining a constant internal temperature, vital for homeostasis. Normal body temperature is 98.6 degrees Fahrenheit. This involves balancing heat produced through cellular metabolism and heat lost, largely regulated by the skin.

Hypothalamus (in Thermal Regulation)

Controls the functions to regulate body temperature. When body temperature rises, it signals dermal blood vessel walls to relax, allowing more blood to surface and heat to escape. When temperature falls, it signals dermal blood vessels to contract, reducing heat flow, and sweat glands to remain inactive. If needed, the nervous system stimulates muscle fibers to contract (shiver) to produce heat.

Radiation (Heat Loss)

The primary means of heat loss, where infrared heat rays escape from a warmer surface to cooler surroundings in all directions.

Conduction (Heat Loss)

Heat moves directly from the body into the molecules of cooler objects in contact with it. Example: Sitting on a cold metal bench.

Convection (Heat Loss)

Involves a continuous circulation of cooler air warmed over a surface. As the air heats, it moves away, carrying heat, and is replaced by cooler air. This continuous cycle leads to heat loss.

Evaporation (Heat Loss)

Occurs when the nervous system stimulates sweat glands to release sweat onto the skin's surface. As sweat evaporates, it carries heat away from the surface, cooling the skin.

Hypothermia

An excessively lowered body temperature, resulting from prolonged cold exposure or illness. It begins with shivering, progressing to coldness, mental confusion, lethargy, loss of reflexes and consciousness, and eventual organ shutdown.

Hyperthermia

An elevated body temperature beyond normal limits. The body cools via blood vessel dilation and sweat secretion. In humid environments, sweat evaporation is difficult, leading to discomfort. If ambient air temperature is higher than body temperature, the core temperature can rise, potentially causing circulatory system collapse.

Fever

The body's self-induced hyperthermic response to fight infection. Infectious agents stimulate phagocytes to release endogenous pyrogen, which raises the hypothalamus's temperature set point. The body responds by increasing heat production, decreasing blood flow to the skin, and reducing sweat secretion, leading to a rise in body temperature. This helps the immune system kill pathogens.

Anabolism

A pathway of cell metabolic reactions where larger molecules are constructed from smaller ones, requiring an input of energy.

Catabolism

A pathway of cell metabolic reactions where larger molecules are broken down into smaller ones, releasing energy.

Catalyst

A particular molecule that can change the rate of a chemical reaction without itself being consumed. Heat is one form of energy that acts as a catalyst.

Enzymes

Specific molecules that promote specific chemical reactions within cells by lowering the activation energy needed to start these reactions. The body uses enzymes to make life reactions possible when body temperature is too mild. Enzyme names often end with '-ase'.

Oxygenation

The essential physiological need for the body to have adequate oxygen for proper cardiovascular function and to supply tissues with oxygen, sourced from respirations. It begins at the cellular level.

Red Blood Cells (RBCs)

Cells responsible for producing hemoglobin, which transports oxygen throughout the body. Good nutrition, especially B12 and folic acid, is vital for their production.

Hemoglobin

A protein in red blood cells that bonds with almost all oxygen (98%) in the blood for circulation to body tissues.

Partial Pressure of Oxygen (PaO2)

Measures oxygen pressure in arterial blood, reflecting how well oxygen moves from the lungs to the blood. A greater PaO2 means more oxygen can combine with hemoglobin for circulation. It's a sensitive indicator altered by severe illnesses.

Nutrition

The result of consuming nutrients and breaking them down through bodily functions to build strong bodies and promote a healthy lifestyle. Nutrients provide heat or energy, build and repair tissue, and regulate life processes.

Calorie

A unit for measuring energy. Kilocalories (1,000 calories) are used for food energy, representing the heat produced when food is metabolized. One gram of protein or carbohydrates yields four calories, one gram of fat yields nine calories, and one gram of alcohol yields seven calories.

MyPlate

A food guidance system developed by the USDA, designed to be consumer-friendly, visually showing that about half of an individual's plate should consist of fruits and vegetables to promote a healthy diet.

Dietary Guidelines (USDA)

Published by the USDA every 5 years, these guidelines advise following a healthy diet plan, focusing on nutrient-dense foods, limiting caloric intake from saturated fats/added sugars, minimizing sodium intake, and making healthy food/drink decisions.

Proteins (Nutrient)

Found in all cells, essential for tissue growth and repair. Sources include dairy products, meat, fish, poultry, eggs, cereals, some vegetables, and nuts. One gram yields four calories.

Carbohydrates (Nutrient)

Essential for energy and provide fiber for bowel elimination. Sources include fruits, vegetables, cereals, breads, and sugar. One gram yields four calories.

Fats (Nutrient)

Provide energy, assist in maintaining body temperature, and help metabolize some vitamins. Sources include dairy products, eggs, meat, oils, and nuts.

Vitamins

Organic compounds that must be present for normal metabolic processes to occur in the body. They are essential to obtain through a well-balanced diet because the body cannot synthesize adequate amounts.

Water-Soluble Vitamins

Vitamins that help oxidize carbohydrates, lipids, and proteins. They cannot be stored by the body and must be ingested daily (e.g., B vitamins, Vitamin C).

B12 (Cobalamin/Cyanocobalamin)

A water-soluble B-complex vitamin found in meats (especially organ meats), poultry, eggs, fish, shellfish, and some dairy. It's absorbed in the stomach dependent on intrinsic factor and is crucial for RBC production and DNA synthesis. RDA is 2 μg. Deficiency leads to pernicious anemia and neurological symptoms. Treatment is monthly B12 injections.

Folic Acid (Folacin)

A water-soluble B-complex vitamin found in leafy green vegetables, avocado, orange juice, and kidney beans, though it can be lost when cooked/reheated. RDA is 400 μg/day. Used for RBC production and DNA synthesis; deficiency during pregnancy can cause neural tube defects. Symptoms include sore mouth, diarrhea, anorexia, irritability, and behavioral disorders.

B6 (Pyridoxine)

A water-soluble B-complex coenzyme used in the metabolism of carbohydrates, fats, protein, and amino acids. Found in meats, legumes, peanuts, whole-grain cereals, and bananas, with significant loss when frozen. RDA is 1.6-2 mg/day. Deficiency can lead to peripheral neuropathy, oral sores, depression in adults, or seizures in infants.

Vitamin C (Ascorbic Acid)

A water-soluble vitamin found in fresh fruits and vegetables, especially citrus fruits, tomatoes, and broccoli. Unstable when exposed to heat or air. RDA is 60 mg/day. Necessary for cellular metabolism, collagen formation, normal growth of teeth/gums/bones, iron absorption, and wound/bone fracture healing. Deficiency causes scurvy. Large doses can lead to kidney stones, elevated uric acid, GI issues, and false negative colon cancer tests.

Fat-Soluble Vitamins

Vitamins that dissolve in fats, influenced by lipid absorption (e.g., bile salts). They are stored in moderate quantities in various tissues and are relatively resistant to destruction by cooking or food processing (e.g., Vitamins A, D, E, K).

Vitamin A (Retinol, Retinal, Beta Carotene)

A fat-soluble vitamin processed from plant carotene (yellow-orange/dark-green leafy vegetables) and found in oily saltwater fish, dairy, and eggs. RDA is 800-1,000 IU/day. Necessary for proper night vision, bone/soft tissue development, and maintaining healthy epithelial tissue. Deficiency can cause night blindness, slow growth, and bone/teeth deformities. Overdose (hypervitaminosis A) can lead to irritability, fatigue, insomnia, headaches, and increased intracranial pressure.

Vitamin D (Calciferol, Cholecalciferol, Ergocalciferol)

A fat-soluble vitamin the body can synthesize in small amounts through sunlight on the skin. Dietary sources include fish oils and fortified foods (milk, cereals). RDA is 400 IU/day. Necessary for normal nerve/muscle functioning and regulating calcium/phosphorus absorption for healthy bones and teeth. Deficiency causes rickets and osteoporosis. Overdose can lead to cardiac arrhythmias, vertigo, tinnitus, kidney damage, or convulsions.

Vitamin E (Tocopherol)

A fat-soluble vitamin abundant in cereals, wheat germ, seeds, nuts, vegetable oils, eggs, meat, and poultry. RDA is 30 IU/day. Necessary for normal metabolism, tissue protection (eyes, skin, liver, lungs), regulating vitamin A use/storage, and protecting RBCs. Deficiency is often associated with other disease processes like alcohol abuse or cystic fibrosis. Overdose (over 1,200 IU/day) can prolong clotting times.

Vitamin K (Phytonadione)

A fat-soluble vitamin primarily found in green leafy vegetables, cheese, eggs, and vegetable oils. RDA is 60-80 mg/day. Necessary for blood clotting, often used prophylactically in newborns. Deficiency signs include increased clotting time, petechiae, bruising, and blood in urine/stool.

Blood Clotting

Necessary for blood clotting, often used prophylactically in newborns. Deficiency signs include increased clotting time, petechiae, bruising, and blood in urine/stool. Treatment involves phytonadione.

Minerals

Inorganic elements extracted from soil by plants, essential to human metabolism and health maintenance (homeostasis). They account for about 4% of body weight, concentrated in bones and teeth. Dissolved minerals in body fluids are electrolytes, carrying electrical charges for activities like nerve impulse conduction and heart beating. Principal minerals include sodium (Na), chloride (Cl), potassium (K), calcium (Ca), and iron (Fe).

Sodium and Chloride (Minerals)

Principal minerals in extracellular body fluids, readily absorbed from foods like table salt (NaCl). Kidneys regulate blood concentration of sodium under aldosterone's influence. Together, they maintain electrolyte balance and regulate pH level through extracellular fluid concentration. Deficiency is due to starvation, prolonged fasting, or excessive fluid loss.

Chylomicron

A lipoprotein consisting mainly of triglycerides absorbed from the small intestine. Its function is to transport dietary fats to muscle and adipose cells, where they are used for energy or stored as fat.

Very Low-Density Lipoproteins (VLDL)

Lipoproteins consisting of a relatively high concentration of triglycerides, produced in the liver. Their function is to transport triglycerides synthesized in the liver from carbohydrates to adipose cells. Remnants are converted to LDL.

Low-Density Lipoproteins (LDL)

Lipoproteins consisting of a relatively high concentration of cholesterol, formed from remnants of VLDL molecules that have given up their triglycerides. Their function is to deliver cholesterol to various cells, including liver cells. High cholesterol content in LDL contributes to coronary disease processes.

High-Density Lipoproteins (HDL)

Lipoproteins consisting of a high concentration of protein and a lower concentration of lipids, formed in the liver and small intestine. Their function is to transport remnants of chylomicrons that have given up their triglycerides back to the liver, where most cholesterol is disposed of by secreting it into bile.

Rest

A basic need that helps the body save energy, refreshes the individual, improves vital signs (blood pressure, pulse, respirations, temperature), and promotes tissue healing and repair.

Insomnia

A sleep disorder where an individual cannot sleep, has trouble falling asleep, or wakes up early and cannot fall back asleep.

Sleep Deprivation

A sleep disorder described as interrupted sleep where the quality and amount of sleep are decreased.

Sleepwalking

A sleep disorder where someone leaves their bed and walks around, with no recollection of the event. These events can last 4 minutes or longer and significantly increase the risk of falls.

Growth (Human Development)

Refers to the physical changes that can be measured and occur in a steady and orderly manner, such as height and weight.

Development (Human Development)

Relates to changes in psychological and social functioning, where different age groups generally act appropriately for their age and accomplish specific developmental tasks.

Infant Growth and Development (Birth to One Year)

Characterized by rapid physical, psychological, and social development. Developmental tasks include developing stable sleep patterns, beginning emotional relationships, learning to talk, eating solid foods, and walking. Newborns average 7-7.5 lbs and 20-21 inches, doubling weight by 5-6 months and tripling it by age one, with 10-12 inches of growth. Vision, hearing, smell, and taste are developed at birth, with coordinated movements developing as the nervous system matures.

Toddler Growth and Development (One to Three Years)

Physical growth slows (approx. 4-5 inches between 1 and 2 years), but development rate increases dramatically. Visual acuity is well established by one year. Fine muscle coordination and gross motor skills improve. Toilet training is a major task. Speech and language skills increase, vocabulary grows, and toddlers can form 2-3 word sentences.

Preschool Growth and Development (Three to Six Years)

Less physical growth (height increases 2-3 inches/year, weight ~5 lbs/year) but increased independence and intellectual development. Children are less quarrelsome, developing a sense of right and wrong. Play is important (group play, sharing, simple games, imaginary playmates). They begin to understand time and speak in various tenses. Vocabulary increases (up to 2,100 words by age 5).

Middle Childhood Growth and Development (Six to Eight Years)

Rapid physical growth (height 1-2 inches/year, weight 3-6 lbs/year). School is a significant event. Body proportions become more adult-like; primary teeth are replaced. Vocabulary expands (around 2,500 words at age 6). Children play well with same-sex peers and develop excellent eye-hand coordination.

Late Childhood Growth and Development (Nine to Twelve Years) / Preadolescence

Physical growth continues (males: 1 inch/year, 3-4 lbs/year; females: 2 inches/year, 4-5 lbs/year). Body movements are more graceful. Vocabulary reaches about 7,000 words (50,000 reading). Interest in science/history/geography continues. Children begin to question adult authority and rebel. Peer groups become central, influencing attitudes and behaviors, with a preference for same-sex companions.

Adolescent Growth and Development (12 to 20 Years)

The period between school age and adulthood, characterized by significant physical growth (last period of significant growth) and sexual maturation (puberty begins around 12 for girls, 13 for boys). Girls develop breasts, broad pelvis, fat on hips/chest; boys develop facial/body hair, deepening voice. Emotions vary, striving for independence, dating, and focusing on appearance. Begin to consider careers/college and establish individual lifestyles.

Young Adult Growth and Development (20-40 Years)

Continues physical and emotional maturation. Main goals include choosing a career/occupation and a partner, which are influenced by education, economic stability, and sense of love/belonging. Physical deterioration may begin after age 30 but is usually gradual.