Human physiology is the study of how the human body functions. It encompasses a wide range of topics, including the nervous system, the endocrine system, the cardiovascular system, and the digestive system. In this lesson, we will focus on the nervous system, which is responsible for controlling behavior, sensation, and movement.
The Structure and Function of Neurons
Neurons are the basic building blocks of the nervous system. They are specialized cells that transmit information throughout the body. Neurons have three main parts: the cell body, the dendrites, and the axon. The cell body contains the nucleus and other organelles that are necessary for the neuron to function. The dendrites are short, branching extensions that receive signals from other neurons. The axon is a long, thin extension that transmits signals to other neurons or to muscles or glands.
The Organization of the Nervous System
The nervous system is divided into two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord, while the PNS consists of all the nerves that extend from the CNS to the rest of the body. The PNS is further divided into the somatic nervous system and the autonomic nervous system. The somatic nervous system controls voluntary movements, while the autonomic nervous system controls involuntary functions such as heart rate, digestion, and breathing.
Mechanisms of Neural Communication
Neurons communicate with each other through a process called synaptic transmission. When an action potential reaches the end of an axon, it triggers the release of neurotransmitters into the synapse, which is the small gap between the axon terminal and the dendrite of the next neuron. The neurotransmitters bind to receptors on the dendrite, which can either excite or inhibit the next neuron from firing an action potential.
The Role of the Nervous System in Controlling Behavior, Sensation, and Movement
The nervous system plays a crucial role in controlling behavior, sensation, and movement. The brain is responsible for processing sensory information and generating appropriate responses. For example, when you touch a hot stove, sensory neurons in your skin send a signal to your spinal cord, which then sends a signal to your brain. Your brain processes this information and generates a response, such as pulling your hand away from the stove. The nervous system also controls movement by sending signals from the brain to the muscles.
Conclusion
The nervous system is a complex and fascinating system that is responsible for controlling many of the body's functions. Neurons are the basic building blocks of the nervous system, and they communicate with each other through synaptic transmission. The nervous system is divided into the CNS and the PNS, and it plays a crucial role in controlling behavior, sensation, and movement.
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⇦ 1 Introduction to human physiology 3 The endocrine system ⇨