Human Biology: Tissues, Cancer, Skeletal, Muscular, and Cardiovascular Systems

Comprehensive vocabulary flashcards covering tissues, cancer biology, bone development and joints, muscle contraction, blood composition, and the cardiovascular system based on lecture slides.

Epithelial tissue

Sheets of cells that cover body surfaces and line internal body cavities, such as the outer layer of the skin and the lining of the digestive tract.

Simple squamous epithelium

A single layer of flat cells that facilitates diffusion and filtration, lining blood vessels and the air sacs of lungs.

Simple cuboidal epithelium

A single layer of cube-shaped cells specialized for absorption and secretion, lining kidney tubules and glands.

Simple columnar epithelium

A single layer of tall, column-shaped cells that lines most digestive organs.

Stratified squamous epithelium

A protective multi-layered tissue whose outermost layer consists of flattened cells, found in the outer layers of the skin and mouth.

Basement membrane (basal lamina)

A protein layer that supports epithelial tissue and anchors it to the underlying connective tissues.

Glandular epithelium

Specialized epithelial tissue adapted to secrete products onto epithelial surfaces or release hormones into the bloodstream.

Fibroblasts

The most common cell type in connective tissue that synthesizes extracellular protein fibers, including collagen and elastin.

Loose connective tissue

A supportive connective tissue characterized by a loose arrangement of elastin fibers, collagen fibers, and fibroblasts embedded in ground substance.

Dense connective tissue

A strong connective tissue with many collagen fibers oriented in parallel, containing fewer cells and blood vessels, found in tendons and ligaments.

Cartilage

A smooth, avascular specialized connective tissue that cushions joints to reduce friction and gives shape to body structures like the ear and tip of the nose.

Adipose tissue

A specialized connective tissue found beneath the skin consisting predominantly of adipocytes that function in fat storage, protection, and insulation.

Keratinocytes

The most numerous epidermal cell type that divides in lower layers and produces keratin, a protein that provides strength and waterproofing.

Melanocytes

Epidermal cells that produce melanin, a dark pigment that absorbs and protects skin against ultraviolet (UV) radiation.

ABCD rule (Melanoma detection)

A set of warning signs for identifying melanoma: Asymmetry, irregular Border, Color variation, and Diameter greater than $6\,\text{mm}$.

Oncogene

A mutated or overexpressed gene that produces a constitutively active protein, stimulating continuous, uncontrolled cell division.

Tumor suppressor gene

A gene whose normal protein product halts the cell cycle and prevents improper cell division; mutation leads to inactive protein or loss of expression.

Hyperplasia

An early phase in cancer progression where cells divide at an abnormally rapid rate.

Dysplasia

A stage in cancer development in which cells undergo abnormal changes in their shape and organization.

In situ cancer

A localized tumor where cells have the morphological appearance of cancer but remain confined within their original tissue site.

Metastasis

The dissemination of cancerous cells from a primary tumor through the bloodstream or lymphatic system to establish new tumors in distant organs.

Angiogenesis

The stimulation and development of new blood vessels mediated by chemical signals from tumor cells to supply oxygen and nutrients.

Apoptosis

Programmed cell death triggered when cellular DNA damage is irreparable, serving as a defensive mechanism against tumor formation.

Ligaments

Strong bands of dense connective tissue that connect bones to other bones across a joint.

Tendons

Cords of dense regular connective tissue that attach skeletal muscles to bones.

Chondroblasts

Cartilage-forming cells that construct the initial hyaline cartilage model of future bones during development.

Osteoblasts

Young bone-forming cells that secrete osteoid and enzymes to deposit calcium phosphate crystals and build bone matrix.

Osteocytes

Mature bone cells that maintain the daily metabolism and structural matrix of bone tissue.

Osteoclasts

Large bone-dissolving cells that break down and resorb extracellular bone matrix during growth and remodeling.

Osteoporosis

A disease characterized by progressive bone loss resulting from an imbalance where osteoclast resorption exceeds osteoblast bone deposition.

Sarcomere

The basic functional contractile unit of a muscle fiber containing organized arrays of actin and myosin filaments.

Sarcoplasmic reticulum

A specialized organelle in muscle cells that stores calcium ions ($\text{Ca}^{2+}$) and releases them in response to electrical signals.

Troponin

A regulatory protein on the actin filament that binds calcium ions, shifting tropomyosin away to expose myosin-binding sites.

Motor Unit

A single motor neuron and all the individual muscle cells (fibers) that it innervates.

Slow Twitch Fibers

Endurance-oriented muscle fibers that contract slowly, resist fatigue, rely on aerobic metabolism, and contain numerous mitochondria, blood vessels, and myoglobin.

Fast Twitch Fibers

Strength-oriented muscle fibers that contract rapidly with high power, fatigue quickly, rely on anaerobic metabolism, and have fewer mitochondria and myoglobin.

Intercalated disc

Specialized junctional complexes between cardiac muscle cells containing gap junctions that permit rapid electrical conduction.

Dystrophin

A crucial structural protein linking the internal cytoskeleton of a muscle cell to the extracellular matrix; absence leads to Duchenne Muscular Dystrophy.

Hematocrit

The fraction of total blood volume consisting of erythrocytes (red blood cells), typically amounting to about $44\%$.

Hemoglobin

An iron-containing protein in erythrocytes composed of four subunits, each carrying a heme group that reversibly binds an $\text{O}_2$ molecule.

Leukocytes

White blood cells consisting of neutrophils, eosinophils, basophils, monocytes, and lymphocytes that defend the body against infections and foreign matter.

Erythropoietin (EPO)

A hormone released by oxygen-sensitive cells in the kidneys that triggers red blood cell production within red bone marrow.

Hemostasis

The physiological process that halts blood loss following vessel trauma through vascular spasm, platelet plug formation, and blood coagulation.

Vasoconstriction

The contraction of circular smooth muscle in the wall of an arteriole, decreasing lumen diameter and reducing downstream blood flow.

Vasodilation

The relaxation of circular smooth muscle within an arteriole wall, enlarging the lumen and elevating downstream blood flow.

Precapillary sphincters

Rings of smooth muscle situated at the origin of capillaries that contract or relax to control blood perfusion into the capillary bed.

Myocardium

The middle layer of the heart wall composed of cardiac muscle tissue responsible for the contracting and pumping action.

Pulmonary circuit

The vascular route carrying deoxygenated blood from the right ventricle to the lungs and returning oxygenated blood to the left atrium.

Systemic circuit

The vascular pathway that delivers oxygen-rich blood from the left ventricle out to bodily tissues and channels deoxygenated blood back to the right atrium.

Cardiac cycle

The sequence of mechanical events during a single heartbeat lasting about $0.8\,\text{seconds}$, alternating between contraction (systole) and relaxation (diastole).

Sinoatrial (SA) node

A cluster of specialized autorhythmic cardiac cells in the right atrium that sets the pace for heart contractions, functioning as the natural cardiac pacemaker.

Coronary circulation

The specialized vascular network of coronary arteries branching off the aorta and cardiac veins draining into the right atrium to sustain heart muscle tissue.

Myocardial infarction

A heart attack resulting from an occluded coronary artery, producing ischemia, hypoxia, and necrosis of the affected cardiac muscle tissue.