Human Body Systems Terms and Concepts Levels of organization: tissue, organ, organ system mouth pharynx esophagus stomach small intestine large intestine peristalsis pancreas liver gall bladder red blood cells hemoglobin white blood cells plasma platelets aorta arteries arterioles capillary beds venules veins vena cava heart atria ventricles blood pressure larynx trachea bronchi bronchioles alveoli diaphragm systemic circulation pulmonary circulation kidney nephron glomerulus Bowman’s capsule filtration reabsorption proximal convoluted tubule loop of Henle distal convoluted tubule ureter urinary bladder urethra neuron cell body axon dendrite synapse neurotransmitter myelin sensory neuron motor neuron interneuron central nervous system peripheral nervous system path of blood through the heart, pulmonary circuit, and systemic circuit gas exchange in the pulmonary and systemic circuits diagrams heart respiratory system nephron neuron tympanic membrane nictitating membrane eustachian tubes vomarine teeth