A/P intro midterm

Anatomical position

Standing upright, facing forward, feet together, arms at the sides, palms facing forward.

Levels of organization

Chemical → cellular → tissue → organ → organ system → organism.

Superior / Inferior

Toward the head / toward the feet.

Anterior / Posterior

Front of the body (ventral) / back of the body (dorsal).

Medial / Lateral

Toward the midline / away from the midline.

Proximal / Distal

Closer to / farther from where a limb attaches to the trunk.

Superficial / Deep

Toward the body surface / away from the body surface.

Sagittal plane

Divides the body into left and right parts. A midsagittal plane makes equal halves.

Frontal (coronal) plane

Divides the body into anterior and posterior parts.

Transverse plane

Divides the body into superior and inferior parts. Also called a horizontal plane or cross section.

Dorsal body cavity

The cranial cavity (brain) plus the vertebral canal (spinal cord).

Mediastinum

The central part of the thoracic cavity, between the lungs. It holds the heart, trachea, and esophagus.

Parietal vs. visceral serosa

Parietal lines the cavity wall; visceral covers the organ.

Homeostasis

Keeping a relatively stable internal environment even when conditions change.

Receiver control effect

Senses the change / processes the information and decides on a response / carries out the response.

Negative feedback

A response that reverses the original change. Example: regulating body temperature or blood glucose.

Positive feedback

A response that amplifies the original change until an event ends it. Examples: labor contractions, blood clotting.

Normal blood pH

7.35–7.45 (slightly basic).

Ionic bond

A bond formed when electrons are transferred, which creates oppositely charged ions that attract each other.

Covalent bond

A bond formed when atoms share electrons. It is polar if the sharing is unequal.

Hydrogen bond

A weak attraction between a slightly positive hydrogen and a slightly negative atom. It holds water molecules together and helps shape proteins and DNA.

pH

A measure of H⁺ concentration. Below 7 is acidic, 7 is neutral, above 7 is basic.

Buffer

A substance that resists changes in pH.

Monosaccharide

A simple sugar (e.g., glucose). It is the monomer of carbohydrates.

Glycogen

The storage form of glucose in animals (liver and muscle).

Phospholipid

A lipid with a hydrophilic head and two hydrophobic tails. It is the main part of cell membranes.

Amino acid

The monomer of proteins. Amino acids are joined by peptide bonds.

Enzyme

A protein catalyst that speeds up reactions by lowering activation energy.

ATP

Adenosine triphosphate, the cell's main usable energy molecule.

DNA vs. RNA

DNA: double-stranded, deoxyribose, pairs A-T. RNA: single-stranded, ribose, uses uracil (A-U).

Hydrolysis

Breaking a molecule apart by adding water.

Plasma membrane

A selectively permeable phospholipid bilayer with embedded proteins.

Mitochondria

The organelle that makes most of the cell's ATP through aerobic respiration.

Ribosome

The site of protein synthesis.

Rough ER

ER studded with ribosomes. It makes proteins for export or for membranes.

Smooth ER

ER without ribosomes. It makes lipids, detoxifies, and stores calcium.

Golgi apparatus

Modifies, sorts, and packages proteins into vesicles.

Lysosome

A vesicle of digestive enzymes that breaks down worn-out parts and debris.

Diffusion

The movement of particles from high concentration to low concentration. It needs no ATP.

Osmosis

The diffusion of water across a selectively permeable membrane.

Hypotonic solution

A solution with lower solute concentration than the cell. Water enters and the cell swells and may burst.

Hypertonic solution

A solution with higher solute concentration than the cell. Water leaves and the cell shrinks (crenates).

Sodium-potassium pump

Active transport that moves 3 Na⁺ out of the cell and 2 K⁺ in, using ATP.

Endocytosis / Exocytosis

Taking material into the cell in vesicles / releasing material from the cell in vesicles.

Metaphase

The mitosis phase in which chromosomes line up at the cell's equator.

Epithelial tissue

Covers and lines surfaces and forms glands. It is avascular and sits on a basement membrane.

Simple squamous epithelium

One layer of flat cells built for diffusion and filtration (alveoli, capillaries).

Stratified squamous epithelium

Many cell layers that protect against abrasion (epidermis, mouth, esophagus).

Connective tissue

Cells scattered in an extracellular matrix of ground substance and fibers. It includes bone, cartilage, blood, and adipose.

Collagen

Strong protein fibers that resist pulling (tensile strength).

Cardiac muscle

Striated and involuntary, with intercalated discs. Found only in the heart.

Smooth muscle

Not striated and involuntary. Found in the walls of hollow organs and vessels.

Neuroglia

Support cells of nervous tissue.

Stratum basale

The deepest epidermal layer. Its cells divide, and it contains melanocytes.

Stratum corneum

The outermost epidermal layer: dead, flat, keratin-filled cells.

Keratinocyte

The most common epidermal cell. It makes keratin, a tough protective protein.

Melanocyte

A cell that makes melanin pigment, which protects against UV light.

Dermis

The connective tissue layer under the epidermis. It holds vessels, nerves, hair follicles, and glands.

Sebaceous gland

A gland that secretes sebum (oil), usually into a hair follicle.

Osteoblast

A cell that builds new bone matrix.

Osteoclast

A cell that breaks down (resorbs) bone and releases calcium.

Osteocyte

A mature bone cell that maintains the matrix from inside a lacuna.

Diaphysis / Epiphysis

The shaft of a long bone / the enlarged ends of a long bone.

Epiphyseal plate

The hyaline cartilage growth plate that allows a long bone to grow in length.

Osteon

The structural unit of compact bone: rings of lamellae around a central canal.

Axial skeleton

The skull, hyoid, vertebral column, ribs, and sternum (80 bones).

Appendicular skeleton

The limbs plus the pectoral and pelvic girdles (126 bones).

Sarcomere

The contractile unit of a myofibril, running from one Z disc to the next.

Acetylcholine (ACh)

The neurotransmitter released at the neuromuscular junction to stimulate skeletal muscle.

Sarcoplasmic reticulum

Specialized ER in muscle fibers that stores and releases Ca²⁺.

Troponin / Tropomyosin

Ca²⁺ binds troponin, which shifts tropomyosin off the myosin-binding sites on actin.

Sliding filament theory

Myosin heads pull actin filaments toward the center of the sarcomere, which shortens it.

Motor unit

One motor neuron plus all the muscle fibers it stimulates.

Resting membrane potential

About −70 mV, kept up mainly by K⁺ leakage and the Na⁺/K⁺ pump.

Myelin

A fatty insulating sheath that speeds up nerve impulses. It is made by Schwann cells (PNS) and oligodendrocytes (CNS).