Since the sa node is at the top of the atrial mass, the atria contract from the top down. how does this increase the efficiency of atrial contraction? do the ventricles have a similar arrangement? if so, how does it work?

The fascicles of the deltoid are ; the fascicles of the pectoralis parallel; bipennate fusiform; unipennate multipennate; triangular bipennate; fusiform

80 points pls brainliest 1. what does a red shift mean? blue shift? 2. describe the big bang theory. according to this theory, how old is the universe? 3. scientists believe the universe is expanding. what is the evidence that supports this? 4. describe a nebula. 5. describe the 3 types of galaxies. what is a barred spiral galaxy? 6. what is a light year? how far is alpha centauri from earth? 7. describe the universal law of gravitation. be sure to include gravitational force between two objects. 8. describe the planets’ orbits around the sun. 9. what is the asteroid belt? where is it located? 10. describe rotation and revolution of earth. what determines an earth day and year? 11. how do galaxies exist? 12. compare and contrast the inner and outer planets. 13. what causes the seasons?

Answer questions from exploring further