Human Nervous and Endocrine Systems: Functions and Processes

1. Central Nervous System

• Brain: Protected by the cranium and divided into:
  • Cerebrum: Interprets information from sense organs, controls language, memory, and thought. It produces voluntary responses.
  • Cerebellum: Controls basic movements and helps maintain balance.
  • Brain Stem: Controls involuntary movements.
• Spinal Cord: Protected by the vertebral column. It sends signals to and from the brain and facilitates involuntary responses or reflexes.

2. Autonomic Nervous System

• Sympathetic: Stimulates organs in case of emergency.
• Parasympathetic: Maintains the functioning of the body.

3. Neurons

Neurons are specialized cells of the nervous system that transmit nerve impulses.

4. Synaptic Transmission

The nerve impulse is transmitted from one neuron to another through a connection called a synapse. The pre-synaptic neuron releases chemical substances called neurotransmitters into the gap between both neurons. When neurotransmitters join the membrane of the post-synaptic neuron, the nerve impulse starts again.

5. The Endocrine System

The endocrine system consists of glands that produce hormones and release them into the blood.

Hormones: Chemical messengers that travel through the blood. Each hormone carries a message understood only by one specific type of cell. They are used for controlling gradual changes (e.g., sex hormones) or regulating substance levels in the body (e.g., insulin).

6. Glands and Hormones

• Pancreas: Insulin; controls glucose levels.
• Testes: Testosterone; produces secondary sex characteristics and controls sperm production.
• Thyroid Gland: Thyroxine; controls metabolism.
• Ovaries: Estrogens; produce secondary sex characteristics, regulate the menstrual cycle and pregnancy.
• Pituitary Gland: STH; controls growth.

7. Differences Between Nervous and Endocrine Systems

• Speed of Response: Very fast (Nervous) vs. Slow (Endocrine).
• Purpose: Quick actions like movement (Nervous) vs. Controlling gradual processes and regulating substance levels (Endocrine).
• Response Lasting: Short-lasting (Nervous) vs. Long-lasting (Endocrine).
• Transmission Method: Electrical impulses travel along nerves (Nervous) vs. Hormones travel through blood (Endocrine).