The Nervous & Endocrine Systems

10-1 Describe the functions of the nervous system’s main divisions, and identify the three main types of neurons.

Main Divisions of Nervous System

Nerves: bundled axons that form neural “cables” connecting CNS w/ muscles, glands, & sense organs

Opponent process: work in opposition to create homeostasis

Few million sensory neurons few million motor neurons billions & billions of interneurons

With some 40 billion neurons, each connecting with roughly 10,000 other neurons, we end up with perhaps 400 trillion synapses…. These complex circuits capable of learning, feeling, & thinking are known as neural networks…. And also as us! Sensory (or afferent) neurons: send information from sensory receptors (e.g., in skin, eyes, nose, tongue, ears) TOWARD the central nervous system. Motor (or efferent) neurons: send information AWAY from the central nervous system to muscles or glands. Interneurons: send information between sensory neurons and motor neurons. Most interneurons are located in the central nervous system.

Reflexes & Brain processing Activity: Form a human neural network (circle, hold hands) Send a signal around using squeeze & time it Now turn & form conga line (hands on shoulders) Squeeze one shoulder…. The opposite of the one you feel squeezed… What do you think will happen to our time? Why?

10-2 Describe the nature and functions of the endocrine system and its interaction with the nervous system. The body’s ‘slow’ chemical communication system; a set of glands that secrete hormones into the bloodstream

Hormones… We’ve all got ‘em… Chemical messengers that impact things like: Reproduction Sexual response Hunger Metabolism Stress Growth

If CNS is like texting… then Endocrine is like snail mail… Some hormones are chemically identical to neurotransmitters! Hypothalamus Controls pituitary gland Pituitary gland Secretes many hormones, some of which affect other glands Thyroid gland Affects metabolism Para-thyroids Helps regulate level of calcium in blood Adrenal glands “Fight or flight” response Pancreas Regulates level of sugar in blood Testis Secretes male sex hormones Ovaries Secretes female sex hormones