The Nervous System and The Endocrine System

Nervous System

Central Nervous System (CNS)

• Composed of the brain and spinal cord.

• Receives information from the body, processes it, and sends messages back.

Peripheral Nervous System (PNS)

• Nerves that carry messages to and from the CNS from other parts of the body.

Types of Neurons:

1. Sensory Neurons: Impulse reaches the CNS.

2. Interneurons: Impulse relayed within the CNS.

3. Motor Neurons: Carries impulse to the effector.

• Afferent: Toward the CNS.

• Efferent: Pathway from the CNS.

Endocrine System

Definition

The endocrine system releases hormones into your bloodstream while continuously monitoring levels. It oversees processes such as:

• Metabolism

• Homeostasis (constant internal balance)

• Growth and Development

• Sexual Function

• Reproduction

• Sleep-Wake Cycle

• Mood

Video Notes

• Glands

• Organs

• Cells

Glands & Their Hormones

Pituitary Gland

• Base of brain below hypothalamus

• Regulates metabolism and stress, known as the Master Gland

Pineal Gland

• Produces Melatonin for sleep-wake cycles

• Regulates Circadian Rhythms

Thyroid

• Produces T3 and T4 hormones, including Thyroxine and Triiodothyronine.

Adrenal Glands

• Sit atop each kidney.

• Produce Cortisol and Aldosterone (Adrenal Cortex), and Adrenaline (Adrenal Medulla).

Key Definitions

• Endocrine System: Composed of glands that secrete hormones directly into the bloodstream, acting more slowly yet lasting longer than the nervous system.

• Target Organs: Organs that hormones act upon.

• Hormone: A chemical produced by a gland that has a biological effect on target organs.

Homeostasis

Thermoregulation involves the skin, hypothalamus, blood vessels, and negative feedback.

• Hot:   - Flat Hair
    - Vasodilation (blood vessels move closer to skin making it red)
    - Sweating

• Cold:   - Hair stands up
    - Shivers
    - Vasoconstriction

Graphical Representation