Nervous and Endocrine Systems: Coordination and Regulation

Nervous System Coordination

Nervous coordination is carried out by the nervous system. Neurons are divided into three parts: the cell body, the dendrites, and the axon.

• The cell body contains the nucleus and other organelles.
• Dendrites are short, branch-like projections.
• The axon is a longer projection. It ends in a series of slender branches which widen slightly at the tip and are called axon terminals.

In general, axons are protected by a white substance called myelin. The axons of various neurons sometimes group together to form nerve fibers, and these in turn can group together to form nerves.

Neuron Connection: The Synapse

Neurons are connected to each other. The place where one neuron connects to another is called a synapse. A nerve impulse is a current transmitted by the neuron membrane. In the majority of synapses, there is no physical contact.

Nervous System: Information Processing and Coordination

The nervous system receives information, processes, and coordinates it. The nervous system is made up of the central nervous system (CNS) and the peripheral nervous system (PNS).

Central Nervous System (CNS) Components

It is made up of the encephalon and the spinal cord.

• Encephalon
  • Brain
  • Cerebellum: Controls balance and voluntary movements.
  • Brain Stem: The brainstem links the encephalon to the spinal cord and controls diverse involuntary functions.
• Spinal Cord: The spinal cord is a long, thin bundle of nerves protected by the spine, which links the encephalon to the rest of the body. It coordinates simple responses called reflex actions.

Peripheral Nervous System (PNS)

The PNS connects the CNS to the organs. Nerves are divided into motor and sensory nerves.

• The somatic PNS consists of the sensory nerves and the motor nerves. It controls voluntary movements.
• The autonomic PNS consists of motor nerves which regulate the activity of the internal organs. It controls involuntary movements.
• The sympathetic nervous system stimulates the body to react to stress, fear, etc.
• The parasympathetic nervous system causes the body to relax.

Endocrine System: Regulation of Body Actions

The endocrine system regulates many actions of the body.

Endocrine Glands and Hormones

The main glands which form the endocrine system and the hormones they release are shown in the illustration (not provided in the original text, consider adding an image here for better understanding).