Human Body Systems and Cell Biology

Vocabulary flashcards covering levels of organization, human body systems, the cell cycle, mitosis, cellular differentiation, and homeostasis mechanisms.

Division of labor

The principle that different body structures specialize in different jobs.

Axial skeleton

The skeletal division consisting of $80$ bones.

Appendicular skeleton

The skeletal division consisting of $126$ bones.

Tendons

Connective tissues that connect muscle to bone.

Ligaments

Connective tissues that connect bone to bone.

Skeletal muscle

Muscle tissue that is usually voluntary and moves the skeleton.

Smooth muscle

Involuntary muscle tissue that works in internal organs such as the digestive tract.

Cardiac muscle

Involuntary muscle tissue that makes up the heart.

Dendrites

Neuron structures that receive signals and bring them toward the cell body.

Axon

The part of a neuron that carries signals away from the cell body.

Central nervous system (CNS)

The division of the nervous system consisting of the brain and spinal cord.

Peripheral nervous system (PNS)

Nerves outside the central nervous system, divided into somatic and autonomic branches.

Alveoli

Tiny air sacs surrounded by capillaries where oxygen enters the blood and carbon dioxide leaves the blood.

Arteries

Blood vessels that carry blood away from the heart.

Veins

Blood vessels that return blood to the heart and contain valves.

Capillaries

One-cell-thick blood vessels where the exchange of materials occurs.

Peristalsis

The muscular movement that carries food through the esophagus from the pharynx to the stomach.

Chyme

The liquid substance produced in the stomach after food is churned with hydrochloric acid and pepsin.

Nephrons

Functional units of the kidneys where blood filtration occurs.

Ureters

Tubes that transport urine from the kidneys to the urinary bladder.

Urethra

The tube that carries urine from the urinary bladder to the outside of the body.

Hormone

A chemical messenger released by an endocrine gland into the bloodstream.

Pituitary gland

The master endocrine gland that influences other endocrine glands.

Lymph

A colorless fluid containing white blood cells that is collected from tissues by lymphatic capillaries.

Spleen

A lymphatic organ that filters blood, aids immune defense, and removes old red blood cells and platelets.

Epidermis

The outermost layer of the skin.

Dermis

The middle layer of skin containing capillaries, nerves, glands, hair follicles, and collagen.

Hypodermis

The subcutaneous layer of the skin containing fatty and fibrous tissue, vessels, and nerves that cushions and insulates.

Diaphoresis

The medical term for sweating.

S phase

The cell cycle phase within interphase where DNA replicates and chromosomes duplicate.

Mitosis

The division of the nucleus in the cell cycle.

Cytokinesis

The division of the cytoplasm following nuclear division.

Differentiation

The process by which unspecialized stem cells become specialized during development.

Totipotent

Stem cells that have the developmental potential to form all cell types, including supporting embryonic tissues.

Pluripotent

Stem cells that can form almost all body cell types.

Multipotent

Stem cells that can form related cell types.

Unipotent

Stem cells that can form only one cell type.

Homeostasis

The process of maintaining relatively stable internal conditions, such as temperature, blood glucose, and blood pH.

Negative feedback

A control mechanism that counteracts a change and returns internal conditions toward normal.

Positive feedback

A control mechanism that strengthens an initial change to drive a physiological process forward.

Effector

A feedback loop component that carries out the response directed by the control center.