Week 1 Ana

Organism

Single, complete individual; the highest level of structural organization listed in the notes.

Organ system

A group of organs that carry out basic functions.

Organ

A structure with definite boundaries that has two or more tissue types working together.

Tissue

Similar cells performing a function.

Cell

The smallest unit considered alive.

Organelle

A microscopic structure within a cell that carries out its functions.

Molecule

A particle made of two or more atoms joined by chemical bonds.

Levels of structural complexity

Organism → organ systems → organs → tissues → cells → organelles → molecules.

Integumentary system

Includes the skin, hair, nails, and glands. Functions in protection, water retention, thermoregulation, and sensation.

Skeletal system

Includes bones, cartilages, and ligaments. Provides support, movement, protection, and blood formation.

Muscular system

Consists of skeletal muscles. Functions in movement, communication, control of body openings, and heat production.

Nervous system

Includes the brain, spinal cord, nerves, and ganglia. Provides internal communication, coordination, motor control, and sensation.

Endocrine system

Includes glands and organs such as the pituitary, pineal, thyroid, parathyroid, thymus, adrenal glands, pancreas, testes, and ovaries. Produces hormones.

Circulatory system

Includes the heart and blood vessels. Distributes nutrients, oxygen, wastes, and other substances.

Lymphatic/immune system

Includes lymph nodes and vessels, thymus, spleen, and tonsils. Detects pathogens, makes immune cells, and defends against disease.

Respiratory system

Includes the nose, pharynx, larynx, trachea, bronchi, and lungs. Absorbs O₂, discharges CO₂, and contributes to speech.

Urinary system

Includes the kidneys, ureters, urinary bladder, and urethra. Removes wastes and regulates blood volume, pressure, fluid, and ions.

Digestive system

Includes the esophagus, stomach, small and large intestines, liver, gallbladder, and pancreas. Breaks down and absorbs nutrients.

Reproductive system

Includes the testes, penis, ovaries, vagina, and mammary glands. Involves reproduction, sex hormone secretion, fertilization, fetal development, birth, and lactation.

Anatomical position

Standing with the palms facing forward; the standard reference position for describing the location and orientation of structures.

Sagittal plane

Divides the body or an organ into right and left halves.

Frontal plane

Divides the body or an organ into anterior and posterior portions.

Transverse plane

Divides the body or an organ into superior and inferior portions.

Axial region

Consists of the head, neck, and torso.

Appendicular region

Consists of the upper and lower limbs, also called the appendages.

Thoracic region

A division of the torso.

Abdominal region

A division of the torso.

Brachial region

The arm.

Antebrachial region

The forearm.

Carpal region

The wrist.

Palmar digits

The hand and fingers.

Femoral region

The thigh.

Crural region

The lower leg.

Tarsal region

The ankle.

Pedal digits

The foot and toes.

Cranial cavity

Enclosed by the skull; contains the brain.

Vertebral canal

Enclosed by the bony vertebrae; contains the spinal cord.

Thoracic cavity

Contains the heart and lungs. It is separated from the abdominopelvic cavity by the diaphragm.

Diaphragm

Separates the thoracic cavity from the abdominopelvic cavity.

Mediastinum

The region between the lungs that contains the heart and great vessels.

Abdominopelvic cavity

Divided into the superior abdominal cavity and the pelvic cavity below.

Abdominal cavity

Contains digestive organs, spleen, kidneys, liver, and ureters.

Pelvic cavity

Contains the rectum, urinary bladder, urethra, and reproductive organs.

Plasma membrane

The boundary of the cell that separates the external nonliving environment from the interior of the cell.

Cytoplasm

The material between the plasma membrane and the nucleus.

Receptors

Structures that bind to specific signal molecules such as hormones.

Membrane transport

Movement of molecules that differentiates the interior of the cell from the extracellular environment; includes filtration, simple diffusion, and osmosis.

Surface extensions

Microvilli, cilia, and flagella that extend from the plasma membrane and serve to increase surface area, sensation, and mobility.

Nucleus

organelle containing genetic material (DNA) in chromosomes. (acts as the cell's command center bc DNA directs cellular activity)

Mitochondria

Organelles that are the primary source of ATP; often called the powerhouses of the cell.

Four primary tissue types

Epithelial, connective, nervous, and muscular tissue.

Epithelial tissue

Tissue made of one or more layers of closely adhering cells that provides outer coverings and inner linings of organs.

Simple epithelium

Epithelium consisting of one layer of cells, with each cell attached to the basement membrane.

Stratified epithelium

Epithelium consisting of 2 to 20+ layers of cells, with the deepest layer resting on the basement membrane.

Basement membrane

A layer between epithelial tissue and the underlying connective tissue.

Connective tissue

Tissue with abundant protein fibers that is often specialized to support, bind, and protect organs.

Connective tissue examples

Tendons, ligaments, cartilage, bone, blood, adipose, and lymph.

Nervous tissue

Tissue specialized for rapid transmission of electrical and chemical signals to other cells. Primarily located in the brain and spinal cord, but also found in peripheral nerves and ganglia.

Neuron

A nerve cell that detects stimuli, responds quickly, and transmits information.

Cell body

The part of a neuron that processes stimuli.

Dendrites

Parts of a neuron that receive stimuli.

Axon (nerve fiber)

The part of a neuron that transmits signals.

Neuroglia (glial cells)

Supportive nervous tissue cells that are more abundant than neurons and perform a variety of supportive roles.

Skeletal muscle

The most abundant muscle type. Its cells are long, cylindrical, multinucleated, and striated. It is considered voluntary because most movement is under conscious control.

Cardiac muscle

Muscle found only in the heart. Its cells are striated, have one nucleus, and appear branched. It is involuntary.

Smooth muscle

Muscle that lacks striations and has relatively short, single-nucleus cells. It is involuntary and found in the walls of organs and tubes such as the stomach, intestine, and blood vessels.

Skeletal vs cardiac muscle

Both are striated. Skeletal muscle is generally voluntary and multinucleated, while cardiac muscle is involuntary, has one nucleus, and has branched cells.

Smooth muscle function

Regulates the flow of material from one area to another in organs and tubes.

Gland

A structure that secretes substances.

Endocrine gland

A ductless gland that secretes its products directly into the blood.

Exocrine gland

A gland that secretes substances into a duct, which carries the secretion to a surface.

Cutaneous membrane

The outer layer of skin (epidermis); consists of stratified squamous epithelium.

Mucous membrane

A lubricated lining of interior tubes such as the digestive and respiratory tracts.

Serous membrane

A membrane that produces a watery secretion; often found between two layers of connective tissue.

Synovial membrane

A connective tissue membrane spanning the gap from one bone to the next in some joints; secretes synovial fluid into the joint.

Skin

The main organ of the integumentary system; forms the boundary between the body and the external environment.

Epidermis

The epithelial portion of the skin.

Dermis

The connective tissue portion of the skin; contains blood vessels, sweat glands, and nerve endings.

Hypodermis

Connective tissue underneath the skin that binds the skin to underlying tissue and contains adipose tissue; it is not technically part of the skin.

Accessory structures of the integument

Hair, nails, and cutaneous glands.

Functions of skin

Acts as a barrier against infection and UV radiation, prevents water loss, begins vitamin D synthesis, provides sensation, thermoregulates through dermal blood vessels, and contributes to nonverbal communication through facial expression.

Keratinocytes

Epidermal cells that synthesize the protein keratin.

Stem cells

Epidermal cells that give rise to keratinocytes.

Melanocytes

Epidermal cells found in the stratum basale that synthesize melanin.

Melanin

A pigment that shields DNA from UV radiation.

Tactile cells

Cells that act as receptors for touch in the dermis.

Dendritic cells

Macrophages that guard against pathogens that penetrate the skin.

Stratum basale

The deepest layer of the epidermis; stem cells give rise to young keratinocytes here.

Stratum spinosum

An epidermal layer that contains dendritic cells.

Stratum granulosum

An epidermal layer where keratinocytes are filling with keratin.

Stratum lucidum

The epidermal layer found only in thick skin.

Stratum corneum

The surface epidermal layer containing dead, scaly, keratinized cells that form a tough coating.

Epidermal layers in order

Stratum basale → stratum spinosum → stratum granulosum → stratum lucidum → stratum corneum.

Thick skin

Found on the palms of the hands, soles of the feet, front of the fingers, and bottom of the toes.

Thin skin

Found over most of the body.

Dermal papillae

small, finger-like projections of the dermis that reach up into the epidermis - sensory support

Papillary layer

A thin layer of the dermis that locks the epidermis to the dermis.

Reticular layer

A thicker, deeper layer of the dermis made of thick collagen bundles that provide strength.

Apocrine sweat glands

Scent glands that become active at puberty and release pheromones in response to sexual arousal or stress.

Eccrine sweat glands

Sweat glands that produce watery perspiration that cools the body.