Neurons communicate via electrical impulses called action potentials. When a neuron is stimulated, chemical messengers called neurotransmitters cross the gaps (synapses) between cells. The CNS processes sensory input (what you see, touch, feel), decides on a motor output (movement), and facilitates higher functions like memory, learning, and emotion. The autonomic branch of the PNS controls involuntary functions, regulating heart rate and digestion without conscious effort. The Framework: The Skeletal and Muscular Systems Movement is a defining characteristic of animal life, and it requires a rigid framework and a motor to pull on it. The Skeletal System Anatomy: The adult human skeleton consists of 206 bones, ranging from the tiny stirrup bone in the ear to the massive femur in the thigh. It also includes cartilage, ligaments, and joints. The skeleton is divided into the axial skeleton (skull, spine, ribs) and the appendicular skeleton (limbs).
At the center lies the heart, a four-chambered pump. The vascular system includes arteries (carrying blood away from the heart), veins (returning blood to the heart), and capillaries (tiny vessels where exchange occurs). The blood itself is a fluid tissue containing red blood cells, white blood cells, platelets, and plasma. human anatomy and physiology
The nervous system is divided into the Central Nervous System (CNS)—comprising the brain and spinal cord—and the Peripheral Nervous System (PNS), which consists of nerves extending throughout the body. The brain, protected by the skull, contains billions of neurons. The spinal cord acts as the information highway, transmitting signals between the brain and the body. The autonomic branch of the PNS controls involuntary
While these two terms are often used interchangeably, they represent distinct yet intertwined disciplines. Anatomy is the study of the structure of body parts and their relationships to one another. It answers the question, “What is it and where is it?” Physiology, conversely, is the study of the functions of these body parts. It answers the question, “How does it work?” It also includes cartilage, ligaments, and joints