Resistance also influences total blood flow. resistance is defined as the amount of friction the blood experiences as it travels through the blood vessels. blood flow is always opposed by resistance. friction is due to the contact between blood and the blood vessel wall. the term peripheral resistance is typically used when discussing the resistance of blood in the blood vessels (as opposed to the resistance of blood in the heart). several factors affect this friction, including blood viscosity, blood vessel length, and the size of the lumen of blood vessels (as indicated by vessel radius)

The unique structure of the neuron is dedicated to the efficient and rapid transmission of neural signals. the relationship between neurons, the spinal cord, and the brain constitutes an elaborate communication system throughout the human body. all but one of the functions listed below are a result of this interaction.

The nervous system interacts with the endocrine system by a. using hormones as connections b. sending nerve impulses directly to glands c. using neuroendocrine cells as connections d. sending neurotransmitters directly to neurons

Which statements best describe the differences or similarities between a comparative investigation and an experimental investigation? check all that apply. experimental investigations are best for showing cause-and-effect relationships, while comparative investigations do not necessarily show this type of relationship. comparative investigations are often impractical and unrealistic, while experimental investigations are the most practical and realistic kinds of investigations. comparative investigations allow for the use of a wide range of variables but do not have a control group, while experimental investigations involve variables that can be controlled. both experimental investigations and comparative investigations are designed to answer scientific questions. both experimental investigations and comparative investigations focus on making observations rather than collecting new data.