Goal of the Cardiovascular System: deliver blood to all parts of the body •Does so by using different types of tubing, attached to a pulsatile pump •Elastic arteries •Muscular arteries •Arterioles •Capillaries •Venuoles •Veins •Distribution system broken up into areas called vascular beds •Skin •Digestive (splanchnic) •Muscle
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Goal of the Cardiovascular System: deliver blood to all parts of the body
• Does so by using different types of tubing, attached to a pulsatile pump
Epinephrine (2) Enhance local blood flow to skeletal muscle, heart, liver
Adrenal medulla Hormonal
Acetylcholine (muscarinic)
Erection of clitoris, penis Parasympathetic neurons
neural
Bradykinin Increase blood flow via nitric oxide
Multiple tissues Local
Adenosine Enhance blood flow to match metabolism
Hypoxic cells local
Substances that mediate vascular smooth muscle relaxation
Even though there are many mechanisms for altering the radius of the vascular system, pressure still drops as blood moves further away from the heart. Why?
Resistance = tendency of the vascular system to oppose flow; Flow =
• Influenced by: length of the tube (L), radius of the tube (r), and viscosity of the blood ()
Poiseuille’s Law R = Lr4
• In a normal human, length of the system is fixed, so blood viscosity and radius of the blood vessels have the largest effects on resistance
1R
All four tubes have the same driving pressure. Which tube has the greatest flow? The least flow? Why?
Even with a decrease in overall pressure, the pressure in the vessels is not constant. The pressure in the vessels mirrors the pressures generated in the heart – systolic and diastolic pressures. Systolic = ventricles contracting Diastolic = ventricles filling
Why does the diastolic pressure rise between the left ventricle and the arteries?
Normal blood pressure = 120/80
High blood pressure = 140/90
What could be happening to increase both the diastolic and systolic blood pressure?
Blood Pressure
• Reflects the driving pressures produced by the ventricles
• Because arterial pressure is pulsatile, a single value is used to represent the overall driving pressure. This is called the mean arterial pressure.
MAP = diastolic P + 1/3(systolic P-diastolic P)Why does diastolic pressure account for a greater proportion of the overall value?
SVR = systemic vascular resistance
CO = cardiac output
SV = stroke volume
MAP = Q x Rarterioles
Explain how these two equations are equivalent
What factors influence blood pressure?• Blood volume
• Vascular resistance
• Autoregulation
• Autonomic influences
Regulation of Blood Pressure
• Main coordinating center is in the medulla oblongata of the brain; medullary cardiovascular control center