Kepler's First Law of Planetary Motion States "The Orbits of the Planets

question 22

Multiple Choice

Kepler's first law of planetary motion states "The orbits of the planets are _____ with the Sun at one focus."

• A) spheres
• B) ellipses
• C) circular
• D) rigid
• E) random

---

Definitions:

Conducting System

A network in the heart that electrically controls and coordinates heart muscle contractions.

SA Node

The sinoatrial node, a group of cells in the right atrium of the heart that acts as a natural pacemaker by initiating the heart's electrical impulses.

Purkinje Fibers

Specialized conducting fibers located in the heart's ventricles that help regulate the heart's rhythm.

Heart Skeleton

Fibrous connective tissue that provides a point of attachment for cardiac muscle cells, electrically insulates the atria from the ventricles, and forms the fibrous rings around the valves.