1.3 - Nervous & Endocrine System

Nervous system

Body’s communication network (consists of nerves, neurons, and specialized cells)

Central nervous system (CNS)

Brain and spinal cord

• Command center of the body

• Processes information, coordinates responses, regulates bodily functions

Peripheral nervous system (PNS)

Communication network that transmits sensory information from body to CNS

Autonomic nervous system

Regulates involuntary (automatic) bodily functions

• Consists of sympathetic and parasympathetic nervous system

Sympathetic nervous system

Activates “fight or flight” response

Parasympathetic nervous system

Promotes relaxation and restores body to homeostasis after experiencing stress or danger

Somatic nervous system

Responsible for voluntary movements and relaying sensory information

Neurons

Specialized cell that builds the nervous system

• Cell body (soma)

• Dendrites

• Axon

Glial cells

“Support cells” that provide structural support, insulation, and nourishment to neurons

Motor neurons (Efferent)

Transmits signals from CNS to muscles, glands, and organs

Sensory neurons (Afferent)

Transmits signals from sensory receptors to CNS

Interneurons

Nerve cells that serve as connectors within the CNS

• Relays signals between sensory neurons and motor neurons

Reflex arc

Neural pathway that controls reflexes

• Primitive reflexes (rapid, automatic response)

Endocrine system

System of glands and organs that produce hormones and release them into the bloodstream

Hormones

Chemical messengers produced by glands that travel through the bloodstream to target cells or organs

• Regulates various physiological processes and behaviors

Melatonin

Regulates sleep-wake cycle and circadian rhythms

Oxytocin

Plays a key role in social bonding

• Forming emotional connections, trust, and intimacy

Adrenaline (epinephrine)

Activates body’s stress response and surges during stress, fear, or excitement

• Adrenal gland

Norepinephrine

Involved in regulating arousal, attention, and stress

• Increases heart rate, blood pressure, and alertness

Nerves

Biological communication cables that link the brain and spinal cord to the rest of the body

Glands

Organs of the endocrine system that release hormones

Gonads

Primary reproductive glands—the testes in males and the ovaries in females

• Produces reproductive cells

Pancreas

• Secretes insulin and glucagon to regulate blood sugar

• Produces enzymes to help digest fats, proteins, and carbohydrates

Thyroid gland

Helps regulate brain chemistry, energy levels, and mood