Human Body Systems, Organization, and Physiology

Comprehensive vocabulary flashcards covering the biological hierarchy of cells, tissues, organs, body systems (digestive, circulatory, respiratory, and excretory), as well as physiological disorders and historical scientific discoveries.

Anatomist

A scientist who studies how the body works and examines internal biological structures.

Robert Hooke

An English scientist ($1635\text{--}1703$) who developed an early compound microscope using two lenses and coined the term 'cells' after observing cork tissue.

Compound Microscope

A microscope that utilizes two lenses to achieve greater magnification than a single lens.

Cell

The basic microscopic functional unit of life that works together with other cells to form tissues and maintain living organisms.

Tissue

A group of similar-looking cells that share shape and internal features working together to carry out a specific task.

Connective Tissue

A type of tissue consisting of cells surrounded by a solid or liquid matrix; includes blood, fat, bone, cartilage, tendons, and ligaments.

Muscle Tissue

Contractile tissue designed to generate physical movement; includes skeletal muscle, cardiac muscle in the heart, and smooth muscle.

Nervous Tissue

A tissue composed of nerve cells (neurons) and glial cells that transmits electrical signals to coordinate communication across the body.

Epithelial Tissue

Protective sheets of large, flat cells covering internal and external surfaces that guard against damage, bacteria, and water loss.

Organ

A discrete structure composed of two or more (often all four) tissue types working together to perform a specialized bodily function.

Body System

A network of different organs collaborating to carry out complex life processes and maintain organismal health.

Physical Digestion

The mechanical breakdown of food into smaller pieces without breaking chemical bonds, such as chewing by teeth or churning in the stomach.

Chemical Digestion

The process whereby digestive enzyme molecules break chemical bonds in food particles into smaller nutrients that can pass through cell membranes.

Bolus

A soft, lubricated ball of chewed food formed by the tongue in the mouth before swallowing.

Peristalsis

Involuntary, wave-like contractions of muscular walls that push food through the esophagus and digestive tract.

Amylase

A digestive enzyme present in saliva and pancreatic juice that initiates the chemical breakdown of starches into simpler sugars.

Chyme

The warm, runny, acidic mixture of partially digested food, gastric acid, and digestive enzymes produced in the stomach.

Pepsin

A gastric digestive enzyme activated by hydrochloric acid ($\text{HCl}$) that breaks down dietary proteins into smaller peptide chains.

Bile

A mixture of chemicals produced by the liver and stored in the gallbladder that neutralizes stomach acid and emulsifies fats.

Gallbladder

A small pouch-like accessory organ that stores and concentrates bile until food reaches the small intestine.

Pancreas

An accessory organ that secretes bicarbonate to neutralize stomach acid along with digestive enzymes (protease, lipase, amylase) into the small intestine.

Villi

Tiny, finger-like projections along the inner lining of the small intestine that greatly increase the surface area for nutrient absorption.

Large Intestine

The wider, shorter section of the intestine (colon) responsible for reclaiming water, absorbing remaining vitamins, and hosting symbiotic bacteria.

Caecum

A specialized pouch located between the small and large intestines housing bacteria that break down cellulose in plant-eating animals.

Ruminant

A hoofed animal featuring a four-chambered stomach (rumen, reticulum, omasum, abomasum) designed to digest plant material via bacterial fermentation.

Helicobacter pylori

A spiral-shaped bacterium that damages the protective lining cells of the stomach, causing peptic stomach ulcers.

Gallstones

Hardened crystalline deposits formed in the gallbladder from bile components that can obstruct the bile duct and cause severe pain.

Gluten Intolerance

A digestive condition occurring in individuals lacking the specific enzyme needed to digest the gluten protein molecule found in grains.

Constipation

A condition characterized by blockages and difficulty passing feces through the large intestine, often related to lack of dietary fiber or dehydration.

Gondwana

An ancient southern supercontinent whose geological and fossil matches evidence that Africa, South America, Antarctica, Australia, and India were once united.

Circulatory System

The organ system composed of the heart, blood vessels, and blood that circulates oxygen, nutrients, and waste throughout the body.

Atrium

An upper chamber of the heart (right or left) that collects incoming blood from veins and channels it into a ventricle.

Ventricle

A muscular lower chamber of the heart (right or left) responsible for pumping blood away through arteries to the lungs or systemic circulation.

Septum

The central muscular wall that divides the heart into right (deoxygenated) and left (oxygenated) halves.

Tricuspid Valve

The heart valve situated between the right atrium and right ventricle that prevents blood backflow when the ventricle contracts.

Bicuspid Valve

The atrioventricular valve (also called the mitral valve) located between the left atrium and left ventricle.

Aorta

The largest systemic artery emerging from the left ventricle that distributes oxygen-rich blood to the entire body.

Pulmonary Artery

The blood vessel that carries deoxygenated blood from the right ventricle into the lungs for gas exchange.

Pulmonary Vein

The blood vessel that carries freshly oxygenated blood from the lungs into the left atrium of the heart.

Superior Vena Cava

The large vein that returns deoxygenated blood from the head, neck, and upper body into the right atrium.

Inferior Vena Cava

The large vein that brings deoxygenated blood from the lower limbs and abdomen into the right atrium.

Artery

A thick, muscular blood vessel that transports blood under high pressure away from the heart.

Vein

A blood vessel with thin walls and internal one-way valves that conveys blood back toward the heart under low pressure.

Capillaries

Microscopic blood vessels whose walls are only one cell thick, enabling the exchange of nutrients, gases, and wastes between blood and tissues.

Platelets

Small cell fragments in blood that aggregate and initiate clotting to stop bleeding at the site of a damaged blood vessel.

Plasma

The straw-colored liquid component forming approximately $55\%$ of blood, in which blood cells, nutrients, and waste products are suspended.

Systolic Pressure

The peak blood pressure generated in the arteries during contraction of the heart ventricles.

Diastolic Pressure

The minimum blood pressure measured in the arteries while the heart relaxes and refills between beats.

Sphygmomanometer

A medical instrument equipped with an inflatable cuff and gauge used to measure arterial blood pressure.

Stethoscope

An acoustic diagnostic instrument used to listen to internal heart valve sounds ('lub-dub') and vascular blood flow.

Atherosclerosis

A vascular disease marked by narrowing and hardening of arteries caused by plaque buildup of fats and cholesterol.

Pericarditis

Inflammation and fluid buildup within the pericardium (the thin protective sac enclosing the heart), restricting normal heart contractions.

Sickle Cell Anemia

A genetic blood disorder in which red blood cells become crescent-shaped, hindering normal oxygen transport and capillary circulation.

Cellular Respiration

The chemical oxidation process in cells converting glucose and oxygen into carbon dioxide, water, and usable energy: $\text{glucose} + \text{oxygen} \rightarrow \text{carbon dioxide} + \text{water} + \text{energy}$.

Epiglottis

A cartilaginous flap located at the bottom of the pharynx that folds over the trachea during swallowing to direct food down the esophagus.

Trachea

The cartilaginous airway (windpipe) leading from the larynx down to the primary bronchi.

Alveoli

Millions of microscopic, thin-walled pulmonary air sacs enveloped by capillary meshes where gas exchange occurs.

Diaphragm

A dome-shaped sheet of skeletal muscle below the lungs that contracts downward during inhalation to expand the thoracic cavity.

Gas Exchange

The passive biological process whereby oxygen diffuses from alveolar air into the blood while carbon dioxide diffuses from blood into alveolar air.

Asthma

A chronic inflammatory disorder causing spasms and narrowing of the bronchi and bronchioles, obstructing airflow into the lungs.

Emphysema

A degenerative lung disease, often caused by smoking, in which alveolar walls collapse and break down, severely restricting gas exchange surface area.

Pneumonia

An acute infection of the lungs causing the alveoli to become filled with pus, fluid, and bacteria, hindering gas exchange.

Excretory System

The body system comprising the kidneys, liver, bladder, skin, and lungs responsible for processing and eliminating metabolic toxic wastes.

Nephrons

The microscopic filtering units within the kidney (approximately one million per kidney) that extract waste from blood to form urine.

Urea

A safer nitrogenous waste product produced by the liver from toxic ammonia, which is filtered out of blood by the kidneys.

Organ Transplantation

A surgical procedure whereby a diseased or failing organ in a recipient is replaced with a healthy functioning organ from a donor.