Central Nervous System and Neurons

The central nervous system (CNS) is a crucial component of the body's control and communication network. It consists of the brain and spinal cord, which work together to process information and coordinate responses.

The brain is divided into several regions, each with specific functions:

• Cerebrum: Responsible for memory, learning, and emotions
• Cerebellum: Controls balance and coordination
• Medulla: Regulates vital functions like heart rate and breathing

Neurons are the specialized cells that make up the nervous system. There are three main types of neurons in the nervous system:

1. Sensory neurons: Carry information from receptors to the CNS
2. Interneurons: Transmit signals between sensory and motor neurons
3. Motor neurons: Send signals from the CNS to effectors (muscles or glands)

Vocabulary: Effectors are organs or tissues that respond to nerve impulses, such as muscles or glands.

The nervous system uses electrical impulses to transmit information rapidly throughout the body. These impulses travel along neurons and across synapses, which are gaps between nerve cells.

Definition: A synapse is the junction between two neurons where chemical signals are used to transmit information from one neuron to another.

Reflex arcs are an important feature of the nervous system, providing automatic responses to protect the body from harm. They involve a simple pathway from a sensory receptor through the spinal cord to an effector, bypassing the brain for faster reaction times.

Example: Stepping on a tack triggers a reflex arc, causing the foot to be quickly pulled away before the brain fully processes the pain signal.

Hormonal Control and Endocrine Glands

Hormonal control is a crucial aspect of the body's communication system, working alongside the nervous system to regulate various physiological processes. Hormones are chemical messengers produced by endocrine glands and transported through the bloodstream to target specific tissues.

Key endocrine glands and their functions include:

1. Hypothalamus: Releases hormones that act on other glands
2. Pituitary gland: Produces growth hormone and regulates other glands
3. Thyroid gland: Controls metabolic rate
4. Adrenal glands: Release "fight or flight" hormones
5. Pancreas: Regulates blood glucose levels
6. Ovaries/Testes: Produce sex hormones for reproductive processes

Highlight: Hormones are highly specific, with each hormone acting on particular target tissues that have complementary receptors.

The pancreas plays a crucial role in maintaining blood glucose levels through the production of two important hormones:

1. Insulin: Lowers blood glucose by promoting glucose uptake and storage
2. Glucagon: Raises blood glucose by promoting the conversion of stored glycogen to glucose

Definition: Diabetes is a condition where the body cannot effectively regulate blood glucose levels, either due to insufficient insulin production (Type 1) or reduced insulin effectiveness (Type 2).