Hemodynamics

Question 1

Pressure generated is a result of…

Answer 1

Ventricle contraction

Question 2

Veins

Answer 2

Lower blood pressure tan arteries
Accommodate increased volume
Steady flow, opposite branching patters than arteries
Blood reservoirs

Question 3

Venules

Answer 3

Small veins collecting blood from capillaries

Question 4

Venous Sinuses

Answer 4

No smooth muscle

Question 5

Varicose Veins

Answer 5

Twisted, dilated, superficial veins
Caused by leaky venous valves
Allow back flow and pooling of blood
Deeper veins not susceptible because of surrounding muscles

Question 6

Portal System

Answer 6

Blood flows through two consecutive capillary networks before returning to the heart
Example: hepatic portal system between liver and intestines

Question 7

Anastomoses

Answer 7

Points where two blood vessels merge

Question 8

Arteriovenous Shunt

Answer 8

Artery flows directly into vein
Shunt changes direction of blood flow
Used to decrease heat loss in the cold

Question 9

Venous Anastomosis

Answer 9

Most common blockage
Less serious
Alternative drainage of organs

Question 10

Arterial Anastomosis

Answer 10

Collateral circulation (coronary)

Question 11

Blood Distribution

Answer 11

60% of blood volume at rest is in systemic veins and venules

15% of blood volume is in arteries and arterioles

Question 12

Venous Constriction

Answer 12

Constriction of veins during increased muscular activity or during hemorrhage
Increased Venoconstriction = Increased Preload, Stroke Volume, and Cardiac Output

Question 13

Capillary Exchange

Answer 13

Only occurs across capillary walls between blood and surrounding tissues

Question 14

Three Routes of Capillary Exchange

Answer 14

Intercellular clefts
Fenestrations
Through cytoplasm

Question 15

Mechanisms Involved in Capillary Exchange

Answer 15

Diffusion
Transcytosis
Filtration and reabsorption

Question 16

Filtration

Answer 16

Blood pressure drives fluid out of capillary

High on arterial end, low on venous end

Question 17

Reabsorption

Answer 17

Colloid osmotic pressure draws fluid into capillary
Same on both ends
Results from plasma proteins

Question 18

Oncotic Pressure

Answer 18

Net colloid osmotic pressure

Question 19

Dynamics of Capillary Exchange

Answer 19

Provides tissue with nutrients

Question 20

Net Filtration

Answer 20

At arterial end of capillaries is about 20l/day

Question 21

Net Reabsorption

Answer 21

At venous end of capillaries is about 17l/day

Question 22

Starling’s Law of the Capillaries

Answer 22

Volume of the fluid and solutes reabsorbed is almost as large as the volume filtered

Question 23

Net Filtration Pressure

Answer 23

Determines whether fluids leave or enter capillaries

Question 24

Net Outward Pressure

Answer 24

10 mm Hg at arterial end

Question 25

Net Inward Pressure

Answer 25

9 mm Hg at venous end

Question 26

Edema

Answer 26

An abnormal increase in interstitial fluid if filtration exceeds reabsorption Not noticeable until 30% above normal

Question 27

Result of Excess Filtration

Answer 27

Increased blood pressure | Increased permeability of capillaries allows plasma proteins to escape

Question 28

Result of Inadequate Reabsorption

Answer 28

Decreased concentration of plasma proteins lowers blood colloid osmotic pressure Inadequate synthesis or loss from liver disease, burns, malnutrition, or kidney disease

Question 29

Causes of Edema

Answer 29

Poor venous return Kidney failure Histamine makes capillaries more permeable Obstructed lymphatic drainage

Question 30

Consequences of Edema

Answer 30

Circulatory shock Tissue necrosis Pulmonary edema Cerebral edema

Question 31

Vasoconstriction

Answer 31

Sympathetic stimulation of arterial alpha receptors Decreases diameter Increases blood pressure

Question 32

Vasodilation

Answer 32

Sympathetic stimulation of beta receptors Increases diameter Promotes blood flow

Question 33

Factors Affecting Circulation

Answer 33

Pressure differences that drive the blood flow Resistance to flow Venous return

Question 34

Blood Flow

Answer 34

Amount of blood flowing through a vessel in a given time (ml/min)

Question 35

Perfusion

Answer 35

Rate of blood flow per given mass of tissue (ml/min/g)

Question 36

Hemodynamics

Answer 36

Physical principles of blood flow based on pressure and resistance

Question 37

Flow Equation

Answer 37

DeltaP/R

Question 38

Resistance Equation

Answer 38

1/r^4

Question 39

Blood Flow Equation

Answer 39

r^4

Question 40

Only Possible Immediate Change to Blood Flow

Answer 40

Change in radius