Homeostasis: Keeping the body's internal conditions stable Integumentary system: Skin, hair, nails and glands Epidermis: Outer layer of skin Dermis: Layer of skin with blood vessels, nerves and glands Hypodermis: Fatty layer beneath the skin Melanin: Pigment that gives skin its color and absorbs UV Sebaceous gland: Gland that makes oil (sebum) Sudoriferous gland: Sweat gland Keratin: Tough protein in skin, hair and nails Skeletal system: Bones, cartilage and joints Osteocyte: Mature bone cell Compact bone: Dense outer bone layer Spongy bone: Porous inner bone containing marrow Red bone marrow: Tissue that makes blood cells Ligament: Tissue connecting bone to bone Tendon: Tissue connecting muscle to bone Cartilage: Flexible connective tissue cushioning joints Synovial joint: Freely movable joint with fluid-filled cavity Muscular system: Muscles that produce movement Skeletal muscle: Voluntary striated muscle attached to bones Smooth muscle: Involuntary muscle in walls of organs Cardiac muscle: Involuntary striated muscle of the heart Sarcomere: Basic contractile unit of a muscle fiber Actin and myosin: Protein filaments that slide past each other to contract muscle Nervous system: Brain, spinal cord and nerves Neuron: Nerve cell Synapse: Junction where neurons communicate Cerebrum: Largest part of the brain; thinking and voluntary action Cerebellum: Brain part that coordinates balance and movement Brainstem: Controls breathing, heart rate and basic life functions Autonomic nervous system: Controls involuntary actions Reflex arc: Quick automatic pathway from stimulus to response Myelin: Fatty coating that speeds nerve signals Endocrine system: Glands that release hormones into the blood Hormone: A chemical messenger Pituitary gland: Master gland controlling other glands Thyroid gland: Controls metabolism Pancreas: Makes insulin and digestive enzymes Insulin: Hormone that lowers blood glucose Adrenal gland: Makes hormones such as adrenaline and cortisol Cardiovascular system: Heart and blood vessels Atrium: Upper heart chamber that receives blood Ventricle: Lower heart chamber that pumps blood out Artery: Vessel carrying blood away from the heart Vein: Vessel carrying blood toward the heart Capillary: Tiny vessel where exchange occurs Systolic pressure: Pressure when the heart contracts Diastolic pressure: Pressure when the heart relaxes Erythrocyte: Red blood cell; carries oxygen Leukocyte: White blood cell; fights infection Thrombocyte: Platelet; helps blood clot Hemoglobin: Iron-containing protein that carries oxygen Plasma: Liquid part of blood Lymphatic system: Vessels and organs that drain fluid and defend against disease Lymph node: Small organ that filters lymph Spleen: Organ that filters blood and stores platelets Thymus: Organ where T cells mature Immune system: Cells and tissues that defend against pathogens Antibody: Protein that recognizes and binds to an antigen Antigen: A substance that triggers an immune response Respiratory system: Organs for gas exchange Alveoli: Tiny air sacs in the lungs where gases are exchanged Diaphragm: Muscle under the lungs that drives breathing Trachea: Windpipe Bronchi: Two main airways into the lungs Larynx: Voice box Digestive system: Organs that break down food and absorb nutrients Esophagus: Tube from throat to stomach Peristalsis: Wave-like muscle contractions moving food Stomach: Organ that churns food with acid and enzymes Small intestine: Main site of nutrient absorption Large intestine: Absorbs water and forms stool Liver: Makes bile, processes nutrients and detoxifies Gallbladder: Stores bile Villi: Finger-like folds that absorb nutrients in the small intestine Urinary system: Organs that filter blood and remove liquid waste Kidney: Filters blood and makes urine Nephron: Filtering unit of the kidney Ureter: Tube from kidney to bladder Urinary bladder: Stores urine Urethra: Tube carrying urine out of the body Reproductive system: Organs for producing offspring Gamete: A reproductive cell: sperm or egg Ovary: Female organ that makes eggs Testis: Male organ that makes sperm Uterus: Organ where a fetus develops Zygote: Cell formed when sperm fertilizes an egg Fetus: Developing baby after about eight weeks Placenta: Organ that nourishes the fetus Anatomical position: Standing upright, facing forward, palms forward Sagittal plane: Divides the body into left and right Frontal (coronal) plane: Divides the body into front and back Transverse plane: Divides the body into top and bottom Proximal: Closer to the point of attachment Distal: Farther from the point of attachment Superior: Toward the head Inferior: Toward the feet Anterior: Toward the front Posterior: Toward the back Medial: Toward the midline Lateral: Away from the midline Superficial: Near the surface Deep: Farther from the surface Free flashcards from Peabody at peabody.kids/flashcards/tp-med-body-systems