CH 5: Nervous System
What is the size principle?
motor units are recruited from smallest to largest
Define stroke volume.
amount of blood pumped per contraction of ventricles
What is the importance of alveoli?
gas exchange takes place here
What is the difference between myelinated and unmyelinated nerves?
Myelinated: conduct impulses using saltatory conduction
Unmyelinated: use local conduction and conduct action potential along nerve fibers
What are the Nodes of Ranvier? What do they allow?
small gaps in the myelin sheath that allow action potentials to jump from node to node along an axon
Define hemoglobin.
protein (globin) and iron-containing pigment (heme) necessary for binding oxygen and transporting them
What is pulmonary ventilation?
movement of air into and out of the lungs and breathing
What is a motor unit?
a single motor neuron and all the muscle fibers it innervates
What is rate coding?
the frequency at which a motor neuron sends an impulse to a muscle fiber
What is Fick's equation?
Oxygen Delivery = blood flow x a-VO2 diff
Define tidal volume.
amount of air moved per breath
What is the Frank-Starling Mechanism?
increased venous return stretches or "preloads" the ventricle, causing reactionary increase in contractile force of the ventricle
Describe the difference between twitch and tetanus?
Twitch: a motor unit's response to a single nerve impulse in a muscle
Tetanus: a sustained muscle contraction in response to a nerve impulse
Name the steps of blood flow through the heart.
right atrium > tricuspid valve > right ventricle > pulmonary valve > pulmonary arteries > lungs > pulmonary veins > left atrium > bicuspid (mitral) valve > left ventricle > aortic valve > aorta > body
What is the oxyhemoglobin dissociation curve?
a graph that shows the relationships between partial pressure and the percentage of hemoglobin saturated with oxygen
Which ventricle has a greater wall thickness due to more myocardial muscle?
left
What are the chronic effects of long-term aerobic training?
plasma volume increases 12-20%, resulting in increased EDV, SV, and Q, improved blood transport and performance, temperature regulation
What is the importance of the sigmoidal shape in the oxyhemoglobin dissociation curve?
it optimizes O2 loading in lungs, transport in blood, and unloading in tissues making O2 delivery efficient based on the body's needs
Describe Dalton's Law.
total pressure of gas mixture = sum of partial pressures of each gas; each gas moves according to its own individual pressure gradient