Nervous and Endocrine Systems: Functions and Components

The Neuron: Signal Transmission

Neurons receive and transmit signals via nerve impulses. These impulses travel along the neuron’s plasma membrane in one direction. The process begins at the dendrites with electrical waves, continues through the neuron, and reaches the axon. The synapse, a buffer zone between the axon’s terminal branches, facilitates signal transmission using chemical neurotransmitters.

Brain Structure and Function

Brain: The outermost layer, the cerebral cortex, exhibits gray folds called gyri. Deep fissures divide the brain into lobes. The interhemispheric fissure separates the brain into two hemispheres. The white matter contains the corpus callosum.

Brain Functions

• Voluntary movements
• Conscious sensation
• Intelligence, control, and memory
• Hunger and thirst
• Control of the pituitary gland, which regulates other endocrine glands

Cerebellum and Medulla

Cerebellum: The cerebellum, with its peripheral gray matter, is formed by cerebellar hemispheres. It coordinates movements and maintains balance.

Medulla: The medulla, in contact with the spinal cord, contains peripheral white matter for information transmission. Its gray center monitors vital functions like pulmonary ventilation.

Spinal Cord

Spinal Cord: The white matter serves as a pathway for information. The gray matter facilitates reflex actions.

Peripheral Nervous System

Peripheral Nervous System: This system consists of nerves and neuronal bodies. Accumulations of gray matter, called ganglia, are found instead of nerve bodies. Nerves are collections of neurons, which can be:

• Sensory: Carry information from receptors to the nervous system center.
• Motor: Carry information from the nervous system center to effectors.
• Mixed: Perform both sensory and motor functions.

Endocrine System

Endocrine System: This system comprises endocrine glands that release hormones into the bloodstream. Hormone production and destruction are self-regulated. Feedback mechanisms, like trophic feedback, regulate gland activity. Hormones target specific organs or glands, triggering actions. Key glands include:

• Pituitary: Produces trophic hormones and oxytocin.
• Thyroid: Located in the neck, produces thyroxine, which regulates metabolism.
• Parathyroid: Attached to the thyroid, controls calcium levels.
• Pancreas: Produces insulin and pancreatic juice.

Voluntary Actions

Voluntary Actions: These are conscious responses processed in the brain. Sensory nerves transmit stimuli to the cerebellum, which analyzes and generates a response.

Reflex Actions

Reflex Actions: These actions do not involve the brain, resulting in faster responses. The process involves:

• A receptor capturing the stimulus.
• A sensory neuron carrying the impulse to the spinal cord.
• An association neuron in the spinal cord.
• A motor neuron carrying the impulse to the effector.
• The effector producing the response.