Exam 2: circulation Flashcards
Main function of systemic circulation
Deliver oxygen, nutrients to tissues and remove CO2 and waste
Systemic arteries carry blood under _____ out to tissue beds
High pressure
Arterioles and pre capillary sphincters act as
Control valves to regulate local flow
___ one cell layer thick
Capillaries
Functional unit of circulatory system
Capillaries
Capillaries exchange between
Tissues and blood
Venues collect blood from
Capillaries
Systemic veins return blood and act as
Dynamic storage
Blood flow proportional to ____ EXCEPT in ___
Metabolic demand
Lungs
Cardiac output controlled by
Local systemic tissue flow
Arterial pressure control ____ of local flow or cardiac output
Independent
Composition of aorta
Elastic tissue > fibrous tissue> smooth muscle
Composition of typical artery
Smooth muscle > elastic tissue > fibrous tissue
Composition of vein
Elastic tissue = smooth muscle = fibrous tissue
Composition of capillary
Only endothelium
At a given flow, greater drop in P in a segment =
Greater resistance to flow
Greatest resistant to flow occurs in
Pre-capillary resistance vessels
Systemic circulation is predominantly a
Parallel circuit
Advantages of parallel circuit
- Independence of local flow control
- Minimize total peripheral resistance
- Oxygen rich blood supply to every tissue
Total vascular resistance equal to
Sum of total pulmonic resistance + total peripheral resistance
Viscosity of blood
3
Viscosity of blood due to
RBCs
Viscosity of plasma
1.5
Viscosity of water
1
Velocity decrease =
Increase viscosity
___ increases flexibility of RBC’s and is 3rd most abundant protein in plasma
Fibrinogen
Cells line up in small vessels, which ____
Decreases viscosity
Normal range of hematocrit
38%-45%
Laminar flow
Streamline
Silent
Most efficient
Normal
Turbulent flow
Cross mixing
Vibrational noise
Least efficient
Associated with disease
A vessel may be occluded ____ before problems occur
75%
R < 2000, flow usually
Laminar
R > 3000, flow usually
Turbulent
Broad band associated with
Turbulent flow
Narrow band associated with
Laminar flow
RBCs moving forward transmitter compress sound waves and cause
Increase in frequency of returning waves
Distensibility
Ability of vessel to stretch
Compliance
Ability of vessel to stretch and hold volume
____ are more compliant and distensible
Veins
Systemic arteries, small change in volume associated with
Large change in pressure
Systemic veins, large change in volume associated with
Small change in pressure
Short term control of blood flow involves
Vasodilation
Vasoconstriction
Long term control of blood flow involves
Changes in tissue vascularity
Release of PGI2
Inhibit platelet aggregation
Relax vascular smooth muscle